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Sample records for two-photon photosensitized singlet

  1. Molecular Tuning of Phenylene-Vinylene Derivatives for Two-Photon Photosensitized Singlet Oxygen Production

    DEFF Research Database (Denmark)

    Nielsen, Christian B.; Arnbjerg, Jacob; Johnsen, Mette

    2009-01-01

    that can deviate from the norm, a full investigation of the photophysical properties of the system is generally required. For example, it is acknowledged that the introduction of a ketone moiety to the sensitizer chromophore often results in more efficient production of singlet oxygen. However, we show...... here that the introduction of a carbonyl into a given phenylene-vinylene can, rather, have adverse effects on the yield of singlet oxygen produced. Using these molecules, we show that care must also be exercised when using qualitative symmetry-derived arguments to predict the relationship between one...

  2. Two-Photon Irradiation of an Intracellular Singlet Oxygen Photosensitizer: Achieving Localized Sub-Cellular Excitation in Spatially-Resolved Experiments

    DEFF Research Database (Denmark)

    Pedersen, Brian Wett; Breitenbach, Thomas; Redmond, Robert W.

    2010-01-01

    The response of a given cell to spatially-resolved sub-cellular irradiation of a singlet oxygen photosensitizer (protoporphyrin IX, PpIX) using a focused laser was assessed. In these experiments, incident light was scattered over a volume greater than that defi ned by the dimensions of the laser...

  3. The development of efficient two-photon singlet oxygen sensitizers

    DEFF Research Database (Denmark)

    Nielsen, Christian Benedikt

    the singlet oxygen yield and the two-photon absorption cross section, where it was revealed that a careful balancing of the amount of charge transfer present in theexcited state of the sensitizer is necessary to obtain both a high singlet oxygen quantum yield and a high two-photon cross section. An increasing...... amount of charge-transfer is beneficial for high two-photon absorption cross sections but iscounter-productive for singlet oxygen generation. The design principles obtained from the studies in lipophilic solvents were applied to synthesize water-soluble twophoton singlet oxygen sensitizers......The development of efficient two-photon singlet oxygen sensitizers is addressed focusing on organic synthesis. Photophysical measurements were carried out on new lipophilic molecules, where two-photon absorption cross sections and singlet oxygen quantumyields were measured. Design principles...

  4. Two-Photon Photosensitizer-Polymer Conjugates for Combined Cancer Cell Death Induction and Two-Photon Fluorescence Imaging: Structure/Photodynamic Therapy Efficiency Relationship.

    Science.gov (United States)

    Cepraga, Cristina; Marotte, Sophie; Ben Daoud, Edna; Favier, Arnaud; Lanoë, Pierre-Henri; Monnereau, Cyrille; Baldeck, Patrice; Andraud, Chantal; Marvel, Jacqueline; Charreyre, Marie-Thérèse; Leverrier, Yann

    2017-12-11

    One of the challenges of photodynamic therapy is to increase the penetration depth of light irradiation in the tumor tissues. Although two-photon excitation strategies have been developed, the two-photon absorption cross sections of clinically used photosensitizers are generally low (below 300 GM). Besides, photosensitizers with high cross section values are often non-water-soluble. In this research work, a whole family of photosensitizer-polymer conjugates was synthesized via the covalent binding of a photosensitizer with a relatively high cross section along a biocompatible copolymer chain. The resulting photosensitizer-polymer conjugates were water-soluble and could be imaged in cellulo by two-photon microscopy thanks to their high two-photon absorption cross sections (up to 2600 GM in water, in the NIR range). In order to explore the structure/photodynamic activity relationship of such macromolecular photosensitizers, the influence of the polymer size, photosensitizer density, and presence of charges along the polymer backbone was investigated (neutral, anionic, cationic, and zwitterionic conjugates were compared). The macromolecular photosensitizers were not cytotoxic in the absence of light irradiation. Their kinetics of cellular uptake in the B16-F10 melanoma cell line were followed by flow cytometry over 24 h. The efficiency of cell death upon photoactivation was found to be highly correlated to the cellular uptake in turn correlated to the global charge of the macromolecular photosensitizer which appeared as the determining structural parameter.

  5. Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

    International Nuclear Information System (INIS)

    Barik, Atanu; Indira Priyadarsini, K.; Hari Mohan; Bajaj, P.N.; Sapre, A.V.; Mittal, J.P.; Mukherjee, T.

    2006-10-01

    Singlet molecular oxygen ( 1 O 2 ) is an excited state of molecular oxygen, having antiparallel spin in the same π antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

  6. Singlet Oxygen Detection Using Red Wine Extracts as Photosensitizers.

    Science.gov (United States)

    Lagunes, Irene; Vázquez-Ortega, Fernanda; Trigos, Ángel

    2017-09-01

    Moderate consumption of red wine provides beneficial effects to health. This is attributed to polyphenol compounds present in wine such as resveratrol, quercetin, gallic acid, rutin, and vanillic acid. The amount of these antioxidants is variable; nevertheless, the main beneficial effects of red wine are attributed to resveratrol. However, it has been found that resveratrol and quercetin are able to photosensitize singlet oxygen generation and conversely, gallic acid acts as quencher. Therefore, and since resveratrol and quercetin are some of the most important antioxidants reported in red wines, the aim of this research was to evaluate the photosensitizing ability of 12 red wine extracts through photo-oxidation of ergosterol. The presence of 1 O 2 was detected by ergosterol conversion into peroxide of ergosterol through 1 H NMR analysis. Our results showed that 10 wine extracts were able to act as photosensitizers in the generation of singlet oxygen. The presence of 1 O 2 can damage other compounds of red wine and cause possible organoleptic alterations. Finally, although the reaction conditions employed in this research do not resemble the inherent conditions in wine making processing or storing, or even during its consumption, this knowledge could be useful to prevent possible pro-oxidant effects and avoid detrimental effects in red wines. © 2017 Institute of Food Technologists®.

  7. In-vitro singlet oxygen threshold dose at PDT with Radachlorin photosensitizer

    Science.gov (United States)

    Klimenko, V. V.; Shmakov, S. V.; Kaydanov, N. E.; Knyazev, N. A.; Kazakov, N. V.; Rusanov, A. A.; Bogdanov, A. A.; Dubina, M. V.

    2017-07-01

    In this present study we investigate the Radachlorin photosensitizer accumulation in K562 cells and Hela cells and determined the cell viability after PDT. Using the macroscopic singlet oxygen modeling and cellular photosensitizer concentration the singlet oxygen threshold doses for K562 cells and Hela cells were calculated.

  8. Singlet oxygen-based electrosensing by molecular photosensitizers

    Science.gov (United States)

    Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; de Wael, Karolien

    2017-07-01

    Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

  9. Phosphorescence dynamics of singlet oxygen and Radachlorin photosensitizer in aqueous solution

    Science.gov (United States)

    Belik, V. P.; Beltukova, D. M.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.

    2017-07-01

    The luminescence spectrum of aqueous solution of Radachlorin photosensitizer in the near IR spectral range (950-1350 nm) has been determined at the excitation in both the Soret and Q absorption bands. Major sources of the recorded luminescence were analyzed. Kinetics of photosensitizer and singlet oxygen phosphorescence signals were studied by means of time-resolved spectroscopy. The corresponding characteristic lifetimes were determined.

  10. Single Cell Responses to Spatially Controlled Photosensitized Production of Extracellular Singlet Oxygen

    DEFF Research Database (Denmark)

    Pedersen, Brian Wett; Sinks, Louise E.; Breitenbach, Thomas

    2011-01-01

    The response of individual HeLa cells to extracellularly produced singlet oxygen was examined. The spatial domain of singlet oxygen production was controlled using the combination of a membrane-impermeable Pd porphyrin-dendrimer, which served as a photosensitizer, and a focused laser, which served...... to localize the sensitized production of singlet oxygen. Cells in close proximity to the domain of singlet oxygen production showed morphological changes commonly associated with necrotic cell death. The elapsed post-irradiation “waiting period” before necrosis became apparent depended on (a) the distance...... between the cell membrane and the domain irradiated, (b) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced, and (c) the lifetime of singlet oxygen. The data imply that singlet oxygen plays a key role in this process of light-induced cell death. The approach...

  11. Fluorescent proteins as singlet oxygen photosensitizers: mechanistic studies in photodynamic inactivation of bacteria

    Science.gov (United States)

    Ruiz-González, Rubén.; White, John H.; Cortajarena, Aitziber L.; Agut, Montserrat; Nonell, Santi; Flors, Cristina

    2013-02-01

    Antimicrobial photodynamic therapy (aPDT) combines a photosensitizer, light and oxygen to produce reactive oxygen species (ROS), mainly singlet oxygen (1O2), to photo-oxidize important biomolecules and induce cell death. aPDT is a promising alternative to standard antimicrobial strategies, but its mechanisms of action are not well understood. One of the reasons for that is the lack of control of the photosensitizing drugs location. Here we report the use of geneticallyencoded fluorescent proteins that are also 1O2 photosensitizers to address the latter issue. First, we have chosen the red fluorescent protein TagRFP as a photosensitizer, which unlike other fluorescent proteins such as KillerRed, is able to produce 1O2 but not other ROS. TagRFP photosensitizes 1O2 with a small, but not negligible, quantum yield. In addition, we have used miniSOG, a more efficient 1O2 photosensitizing fluorescent flavoprotein that has been recently engineered from phototropin 2. We have genetically incorporated these two photosensitizers into the cytosol of E. coli and demonstrated that intracellular 1O2 is sufficient to kill bacteria. Additional assays have provided further insight into the mechanism of cell death. Photodamage seems to occur primarily in the inner membrane, and extends to the outer membrane if the photosensitizer's efficiency is high enough. These observations are markedly different to those reported for external photosensitizers, suggesting that the site where 1O2 is primarily generated proves crucial for inflicting different types of cell damage.

  12. Virucidal Nanofiber Textiles Based on Photosensitized Production of Singlet Oxygen

    Science.gov (United States)

    Lhotáková, Yveta; Plíštil, Lukáš; Morávková, Alena; Kubát, Pavel; Lang, Kamil; Forstová, Jitka; Mosinger, Jiří

    2012-01-01

    Novel biomaterials based on hydrophilic polycaprolactone and polyurethane (Tecophilic®) nanofibers with an encapsulated 5,10,5,20-tetraphenylporphyrin photosensitizer were prepared by electrospinning. The doped nanofiber textiles efficiently photo-generate O2(1Δg), which oxidize external chemical and biological substrates/targets. Strong photo-virucidal effects toward non-enveloped polyomaviruses and enveloped baculoviruses were observed on the surface of these textiles. The photo-virucidal effect was confirmed by a decrease in virus infectivity. In contrast, no virucidal effect was detected in the absence of light and/or the encapsulated photosensitizer. PMID:23139839

  13. Inactivation of Neurospora crassa conidia by singlet molecular oxygen generated by a photosensitized reaction

    International Nuclear Information System (INIS)

    Shimizu, M.; Egashira, T.; Takahama, U.

    1979-01-01

    Photodynamic damage of Neurospora crassa conidia was studied in the presence of the photosensitizing dye, toluidine blue O. Conidia which germinated to form colonies decreased in number as irradiation time became longer. The photoinactivation of conidia was suppressed by azide, bovine serum albumin, and histidine, and was stimulated in deuterium oxide. Wild-type conidia were less sensitive to the irradiation that albino conidia. In the wild type, carotenoid-enriched conidia were more resistant against the lethal damage than the conidia which contained small amounts of carotenoids. These results suggest that singlet molecular oxygen causes photodynamic lethal damage to N. crassa conidia and that singlet molecular oxygen is quenched by endogenous carotenoids

  14. Impact of photosensitized oxidation and singlet oxygen on degradation of stabilized polymers

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Jan; Nešpůrek, Stanislav; Pilař, Jan

    2008-01-01

    Roč. 93, č. 9 (2008), s. 1681-1688 ISSN 0141-3910 R&D Projects: GA AV ČR IAA100100622; GA AV ČR KAN400720701; GA AV ČR IAA400500804 Institutional research plan: CEZ:AV0Z40500505 Keywords : photosensitized oxidation * singlet molecular oxygen * oxygenation Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.320, year: 2008

  15. Evaluation of the Medicinal Potential of Two Ruthenium(II) Polypyridine Complexes as One- and Two-Photon Photodynamic Therapy Photosensitizers.

    Science.gov (United States)

    Hess, Jeannine; Huang, Huaiyi; Kaiser, Adrian; Pierroz, Vanessa; Blacque, Olivier; Chao, Hui; Gasser, Gilles

    2017-07-21

    Two [Ru(phen) 2 dppz] 2+ derivatives (phen=1,10-phenantroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine) with different functional groups on the dppz ligand [dppz-7,8-(OMe) 2 (1), dppz-7,8-(OH) 2 (2)] have been synthesized, characterized and investigated as photosensitizers (PSs) for photodynamic therapy (PDT) against cancer. Both complexes showed intense red phosphorescence and promising singlet oxygen ( 1 O 2 ) quantum yields of 75 % (1) and 54 % (2) in acetonitrile. Complex 1 (logP o/w =-0.52, 2.4 nmol Ru per mg protein) was found to be more lipophilic, having also a higher cellular uptake efficiency compared to 2 (logP o/w =-0.20, 0.9 nmol Ru per mg protein). Complex 1 localized evenly in HeLa cells whereas 2, was mainly visualized in the cell membrane by confocal microscopy. In the dark, complex 1 (IC 50 =36.5 μm) was found to be more toxic than complex 2 (IC 50 >100 μm) on a HeLa cells monolayer. Importantly, in view of PDT applications, both complexes were found to be non-toxic in the dark towards multicellular HeLa spheroids (IC 50 >100 μm). Upon one-photon irradiation (420 nm, 9.27 J cm -2 ), 1 exhibited higher phototoxicity (IC 50 =3.1 μm) than 2 (IC 50 =16.7 μm) on HeLa cell monolayers. When two-photon irradiation (800 nm, 9.90 J cm -2 ) was applied, only 1 (IC 50 =9.5 μm) was found to be active toward HeLa spheroids. This study demonstrates that the functional group on the intercalative ligand has a strong influence on the cellular localization and anticancer activity of Ru II polypyridyl complexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Photodynamic biofilm inactivation by SAPYR--an exclusive singlet oxygen photosensitizer.

    Science.gov (United States)

    Cieplik, Fabian; Späth, Andreas; Regensburger, Johannes; Gollmer, Anita; Tabenski, Laura; Hiller, Karl-Anton; Bäumler, Wolfgang; Maisch, Tim; Schmalz, Gottfried

    2013-12-01

    Prevention and control of biofilm-growing microorganisms are serious problems in public health due to increasing resistances of some pathogens against antimicrobial drugs and the potential of these microorganisms to cause severe infections in patients. Therefore, alternative approaches that are capable of killing pathogens are needed to supplement standard treatment modalities. One alternative is the photodynamic inactivation of bacteria (PIB). The lethal effect of PIB is based on the principle that visible light activates a photosensitizer, leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induces phototoxicity immediately during illumination. SAPYR is a new generation of photosensitizers. Based on a 7-perinaphthenone structure, it shows a singlet oxygen quantum yield ΦΔ of 99% and is water soluble and photostable. Moreover, it contains a positive charge for good adherence to cell walls of pathogens. In this study, the PIB properties of SAPYR were investigated against monospecies and polyspecies biofilms formed in vitro by oral key pathogens. SAPYR showed a dual mechanism of action against biofilms: (I) it disrupts the structure of the biofilm even without illumination; (II) when irradiated, it inactivates bacteria in a polymicrobial biofilm after one single treatment with an efficacy of ≥ 99.99%. These results encourage further investigation on the potential of PIB using SAPYR for the treatment of localized infectious diseases. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Highly Charged Ruthenium(II) Polypyridyl Complexes as Lysosome-Localized Photosensitizers for Two-Photon Photodynamic Therapy.

    Science.gov (United States)

    Huang, Huaiyi; Yu, Bole; Zhang, Pingyu; Huang, Juanjuan; Chen, Yu; Gasser, Gilles; Ji, Liangnian; Chao, Hui

    2015-11-16

    Photodynamic therapy (PDT) is a noninvasive medical technique that has received increasing attention over the last years and been applied for the treatment of certain types of cancer. However, the currently clinically used PDT agents have several limitations, such as low water solubility, poor photostability, and limited selectivity towards cancer cells, aside from having very low two-photon cross-sections around 800 nm, which limits their potential use in TP-PDT. To tackle these drawbacks, three highly positively charged ruthenium(II) polypyridyl complexes were synthesized. These complexes selectively localize in the lysosomes, an ideal localization for PDT purposes. One of these complexes showed an impressive phototoxicity index upon irradiation at 800 nm in 3D HeLa multicellular tumor spheroids and thus holds great promise for applications in two-photon photodynamic therapy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Intracellular "activated" two-photon photodynamic therapy by fluorescent conveyor and photosensitizer co-encapsulating pH-responsive micelles against breast cancer.

    Science.gov (United States)

    Luo, Lei; Zhong, Hong; Liu, Shuang; Deng, Lidong; Luo, Yonghuang; Zhang, Qiong; Zhu, Yingzhong; Tian, Yupeng; Sun, Yuan; Tian, Xiaohe

    2017-01-01

    The application of photodynamic therapy (PDT) for the diagnosis and treatment of cancer is hindered by the intrinsic defects of the currently available photosensitizers (PSs), such as poor water solubility and limited light-penetration depth. In this study, pH-responsive polymeric micelles that co-encapsulate therapeutic PSs and organooxotin two-photon compounds were applied for two-photon PDT (TP-PDT) against breast cancer. The TP-PDT effect of the drug-loaded micelles was "activated" when the micelles turned into aggregates at a triggering pH level. The in vitro therapeutic effect was evaluated on 4T1 murine breast cancer cells by viability assays, real-time morphology collapsing, and reactive oxygen species determination. Time-dependent ex vivo organ distribution and in vivo anticancer efficacy results suggested that the drug carriers could accumulate in tumors and suppress tumor growth by TP-PDT. The delivery system could enhance the solubility and distribution of PSs and, if administered along with a tissue-penetrating prolonged light source, could thus have good potential for cancer therapy.

  19. Mitochondria-targeted cationic porphyrin-triphenylamine hybrids for enhanced two-photon photodynamic therapy.

    Science.gov (United States)

    Hammerer, Fabien; Poyer, Florent; Fourmois, Laura; Chen, Su; Garcia, Guillaume; Teulade-Fichou, Marie-Paule; Maillard, Philippe; Mahuteau-Betzer, Florence

    2018-01-01

    The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Postsynthetic Incorporation of a Singlet Oxygen Photosensitizer in a Metal-Organic Framework for Fast and Selective Oxidative Detoxification of Sulfur Mustard.

    Science.gov (United States)

    Howarth, Ashlee J; Buru, Cassandra T; Liu, Yangyang; Ploskonka, Ann M; Hartlieb, Karel J; McEntee, Monica; Mahle, John J; Buchanan, James H; Durke, Erin M; Al-Juaid, Salih S; Stoddart, J Fraser; DeCoste, Jared B; Hupp, Joseph T; Farha, Omar K

    2017-01-01

    A fullerene-based photosensitizer is incorporated postsynthetically into a Zr 6 -based MOF, NU-1000, for enhanced singlet oxygen production. The structural organic linkers in the MOF platform also act as photosensitizers which contribute to the overall generation of singlet oxygen from the material under UV irradiation. The singlet oxygen generated by the MOF/fullerene material is shown to oxidize sulfur mustard selectively to the less toxic bis(2-chloroethyl)sulfoxide with a half-life of only 11 min. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Generation and suppression of singlet oxygen in hair by photosensitization of melanin.

    Science.gov (United States)

    Chiarelli-Neto, Orlando; Pavani, Christiane; Ferreira, Alan S; Uchoa, Adjaci F; Severino, Divinomar; Baptista, Maurício S

    2011-09-15

    We have studied the spectroscopic properties of hair (white, blond, red, brown, and black) under illumination with visible light, giving special emphasis to the photoinduced generation of singlet oxygen ((1)O(2)). Irradiation of hair shafts (λ(ex)>400 nm) changed their properties by degrading the melanin. Formation of C3 hydroperoxides in the melanin indol groups was proven by (1)H NMR. After 532-nm excitation, all hair shafts presented the characteristic (1)O(2) emission (λ(em)=1270 nm), whose intensity varied inversely with the melanin content. (1)O(2) lifetime was also shown to vary with hair type, being five times shorter in black hair than in blond hair, indicating the role of melanin as a (1)O(2) suppressor. Lifetime ranged from tenths of a nanosecond to a few microseconds, which is much shorter than the lifetime expected for (1)O(2) in the solvents in which the hair shafts were suspended, indicating that (1)O(2) is generated and suppressed inside the hair structure. Both eumelanin and pheomelanin were shown to produce and to suppress (1)O(2), with similar efficiencies. The higher amount of (1)O(2) generated in blond hair and its longer lifetime is compatible with the stronger damage that light exposure causes in blond hair. We propose a model to explain the formation and suppression of (1)O(2) in hair by photosensitization of melanin with visible light and the deleterious effects that an excess of visible light may cause in hair and skin. Copyright © 2011. Published by Elsevier Inc.

  2. Irradiation- and Sensitizer-Dependent Changes in the Lifetime of Intracellular Singlet Oxygen Produced in a Photosensitized Process

    DEFF Research Database (Denmark)

    Silva, Elsa; Pedersen, Brian Wett; Breitenbach, Thomas

    2012-01-01

    Singlet oxygen, O2(a1Δg), was produced upon pulsed-laser irradiation of an intracellular photosensitizer and detected by its 1275 nm O2(a1Δg) →O2(X3Σg-) phosphorescence in time-resolved experiments using (1) individual mammalian cells on the stage of a microscope and (2) suspensions of mammalian...... appreciably as the cell progresses towards death. The results obtained from cell suspensions reflect key features that differentiate cell ensemble from single cell experiments (e.g., the ensemble experiment is more susceptible to the effects of sensitizer that has leaked out of the cell). Overall, the data...

  3. Synthesis, singlet-oxygen photogeneration, two-photon absorption, photo-induced DNA cleavage and cytotoxic properties of an amphiphilic β-Schiff-base linked Ru(II) polypyridyl–porphyrin conjugate

    International Nuclear Information System (INIS)

    Ke, Hanzhong; Ma, Wanpeng; Wang, Hongda; Cheng, Guoe; Yuan, Han; Wong, Wai-Kwok; Kwong, Daniel W.J.; Tam, Hoi-Lam; Cheah, Kok-Wai; Chan, Chi-Fai; Wong, Ka-Leung

    2014-01-01

    A novel porphyrin–polypyridyl ruthenium(II) conjugate (TPP–Ru), in which the ruthenium(II) polypyridyl moiety is linked to the β-position of the tetraphenylporphyrin via a Schiff base linkage, has been synthesized and characterized by 1 H NMR, HRMS and UV–visible spectroscopy. The relative singlet oxygen quantum yield and two-photon absorption cross-section of this conjugate, together with its photo-induced DNA cleavage and cytotoxic activities were measured. The results show that the amphiphilic ruthenium(II) polypyridyl–porphyrin conjugate is an effective DNA photocleavage agent, with potential application in one- and two-photon absorption anti-cancer photodynamic therapy. - Highlights: • New porphyrin–ruthenium(II) polypyridyl complexes (TTP–Ru) have been synthesized. • The TTP–Ru shows substantial two-photon absorption cross-section (σ 2 =391 GM). • The TTP–Ru exhibits a substantial 1 O 2 quantum yield (0.64±0.13). • The TTP–Ru exhibits a strong DNA cleavage activity upon photo-excitation. • The TTP–Ru is available for in vitro imaging and as a photodynamic therapy agent

  4. Synthesis, singlet-oxygen photogeneration, two-photon absorption, photo-induced DNA cleavage and cytotoxic properties of an amphiphilic β-Schiff-base linked Ru(II) polypyridyl–porphyrin conjugate

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Hanzhong, E-mail: kehanz@163.com [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan, Hubei 430074 (China); Ma, Wanpeng; Wang, Hongda; Cheng, Guoe [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan, Hubei 430074 (China); Yuan, Han [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Wong, Wai-Kwok, E-mail: wkwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Kwong, Daniel W.J. [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Tam, Hoi-Lam; Cheah, Kok-Wai [Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Chan, Chi-Fai; Wong, Ka-Leung [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China)

    2014-10-15

    A novel porphyrin–polypyridyl ruthenium(II) conjugate (TPP–Ru), in which the ruthenium(II) polypyridyl moiety is linked to the β-position of the tetraphenylporphyrin via a Schiff base linkage, has been synthesized and characterized by {sup 1}H NMR, HRMS and UV–visible spectroscopy. The relative singlet oxygen quantum yield and two-photon absorption cross-section of this conjugate, together with its photo-induced DNA cleavage and cytotoxic activities were measured. The results show that the amphiphilic ruthenium(II) polypyridyl–porphyrin conjugate is an effective DNA photocleavage agent, with potential application in one- and two-photon absorption anti-cancer photodynamic therapy. - Highlights: • New porphyrin–ruthenium(II) polypyridyl complexes (TTP–Ru) have been synthesized. • The TTP–Ru shows substantial two-photon absorption cross-section (σ{sub 2}=391 GM). • The TTP–Ru exhibits a substantial {sup 1}O{sub 2} quantum yield (0.64±0.13). • The TTP–Ru exhibits a strong DNA cleavage activity upon photo-excitation. • The TTP–Ru is available for in vitro imaging and as a photodynamic therapy agent.

  5. Photosensitized production of singlet oxygen: spatially-resolved optical studies in single cells

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Kuimova, Marina; Gbur, Peter

    2009-01-01

    be monitored using viability assays. Time- and spatially-resolved optical measurements of both singlet oxygen and its precursor, the excited state sensitizer, reflect the complex and dynamic morphology of the cell. These experiments help elucidate photoinduced, oxygen-dependent events that compromise cell...

  6. New strategies to produce and detect singlet oxygen in a cell

    DEFF Research Database (Denmark)

    Gollmer, Anita

    2012-01-01

    product of the reaction between SOSG and singlet oxygen is itself an efficient singlet oxygen sensitizer and, second, that despite published claims to the contrary, SOSG can, in fact, be incorporated into living mammalian cells. Further, a new fluorescent probe for singlet oxygen called “Aarhus Green...... to achieve a reproducible assessment of cell response to a controlled dose of singlet oxygen produced in a spatially-localized two-photon sensitized experiment. Different assays were used to visualize cell response. In this dissertation, various aspects of fluorescence imaging and two-photon excitation......Singlet oxygen, the first excited electronic state of molecular oxygen, plays a major role in oxygen-dependent photo-induced cell death. In such systems, singlet oxygen is generally produced in a photosensitized process wherein light is absorbed by a molecule (the so-called sensitizer) which...

  7. Single Molecule Atomic Force Microscopy Studies of Photosensitized Singlet Oxygen Behavior on a DNA Origami Template

    DEFF Research Database (Denmark)

    Helmig, Sarah Wendelboe; Rotaru, Alexandru; Arian, Dumitru

    2010-01-01

    DNA origami, the folding of a long single-stranded DNA sequence (scaffold strand) by hundreds of short synthetic oligonucleotides (staple strands) into parallel aligned helices, is a highly efficient method to form advanced self-assembled DNA-architectures. Since molecules and various materials can...... be conjugated to each of the short staple strands, the origami method offers a unique possibility of arranging molecules and materials in well-defined positions on a structured surface. Here we combine the action of light with AFM and DNA nanostructures to study the production of singlet oxygen from a single...

  8. Ion-induced stacking of photosensitizer molecules can remarkably affect the luminescence detection of singlet oxygen in Candida albicans cells

    Science.gov (United States)

    Felgenträger, Ariane; Gonzales, Fernanda Pereira; Maisch, Tim; Bäumler, Wolfgang

    2013-04-01

    Singlet oxygen (O21) is an important reactive intermediate in photodynamic reactions, particularly in antimicrobial PDT (aPDT). The detection of O21 luminescence is frequently used to elucidate the role of O21 in various environments, particularly in microorganisms and human cells. When incubating the fungus, Candida albicans, with porphyrins XF73 (5,15-bis-[4-(3-Trimethylammonio-propyloxy)-phenyl]-porphyrin) or TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)-porphyrin tetra(p-toluenesulfonate)), the O21 luminescence signals were excellent for TMPyP. In case of XF73, the signals showed strange rise and decay times. Thus, O21 generation of XF73 was investigated and compared with TMPyP. Absorption spectroscopy of XF73 showed a change in absorption cross section when there was a change in the concentration from 1×10-6 M to 1×10-3 M indicating an aggregation process. The addition of phosphate buffered saline (PBS) substantially changed O21 luminescence in XF73 solution. Detailed experiments provided evidence that the PBS constituents NaCl and KCl caused the change of O21 luminescence. The results also indicate that Cl- ions may cause aggregation of XF73 molecules, which in turn enhances self-quenching of O21 via photosensitizer molecules. These results show that some ions, e.g., those present in cells in vitro or added by PBS, can considerably affect the detection and the interpretation of time-resolved luminescence signals of O21, particularly in in vitro and in vivo. These effects should be considered for any other photosensitizer used in photodynamic processes.

  9. Identification of singlet oxygen photosensitizes in lambs drinking water in an alveld risk area in West Norway

    DEFF Research Database (Denmark)

    Tønnesen, Hanne Hjorth; Mysterud, Ivar; Karlsen, Jan

    2013-01-01

    Alveld is a hepatogenous photosensitivity disorder in lambs. Although alveld has been known in Norway for more than 100years, there are still questions related to the cause of the disease. Phytoporphyrin has long been incriminated as the photosensitizer in hepatogenous photosensitivity diseases....... Meteorological data indicate a warm and wet May with a high radiation exposure leading up to a colder and wet June with an even higher solar irradiance. The seasonal variation in the amount of photosensitizers in lamb's drinking water combined meteorological data can be important to predict the outbreak...

  10. Ruthenium(II) polypyridyl complexes as mitochondria-targeted two-photon photodynamic anticancer agents.

    Science.gov (United States)

    Liu, Jiangping; Chen, Yu; Li, Guanying; Zhang, Pingyu; Jin, Chengzhi; Zeng, Leli; Ji, Liangnian; Chao, Hui

    2015-07-01

    Clinical acceptance of photodynamic therapy is currently hindered by poor depth efficacy and inefficient activation of the cell death machinery in cancer cells during treatment. To address these issues, photoactivation using two-photon absorption (TPA) is currently being examined. Mitochondria-targeted therapy represents a promising approach to target tumors selectively and may overcome the resistance in current anticancer therapies. Herein, four ruthenium(II) polypyridyl complexes (RuL1-RuL4) have been designed and developed to act as mitochondria-targeted two-photon photodynamic anticancer agents. These complexes exhibit very high singlet oxygen quantum yields in methanol (0.74-0.81), significant TPA cross sections (124-198 GM), remarkable mitochondrial accumulation, and deep penetration depth. Thus, RuL1-RuL4 were utilized as one-photon and two-photon absorbing photosensitizers in both monolayer cells and 3D multicellular spheroids (MCSs). These Ru(II) complexes were almost nontoxic towards cells and 3D MCSs in the dark and generate sufficient singlet oxygen under one- and two-photon irradiation to trigger cell death. Remarkably, RuL4 exhibited an IC50 value as low as 9.6 μM in one-photon PDT (λirr = 450 nm, 12 J cm(-2)) and 1.9 μM in two-photon PDT (λirr = 830 nm, 800 J cm(-2)) of 3D MCSs; moreover, RuL4 is an order of magnitude more toxic than cisplatin in the latter test system. The combination of mitochondria-targeting and two-photon activation provides a valuable paradigm to develop ruthenium(II) complexes for PDT applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Two-Photon-Excited Silica and Organosilica Nanoparticles for Spatiotemporal Cancer Treatment.

    Science.gov (United States)

    Croissant, Jonas G; Zink, Jeffrey I; Raehm, Laurence; Durand, Jean-Olivier

    2018-01-18

    Coherent two-photon-excited (TPE) therapy in the near-infrared (NIR) provides safer cancer treatments than current therapies lacking spatial and temporal selectivities because it is characterized by a 3D spatial resolution of 1 µm 3 and very low scattering. In this review, the principle of TPE and its significance in combination with organosilica nanoparticles (NPs) are introduced and then studies involving the design of pioneering TPE-NIR organosilica nanomaterials are discussed for bioimaging, drug delivery, and photodynamic therapy. Organosilica nanoparticles and their rich and well-established chemistry, tunable composition, porosity, size, and morphology provide ideal platforms for minimal side-effect therapies via TPE-NIR. Mesoporous silica and organosilica nanoparticles endowed with high surface areas can be functionalized to carry hydrophobic and biologically unstable two-photon absorbers for drug delivery and diagnosis. Currently, most light-actuated clinical therapeutic applications with NPs involve photodynamic therapy by singlet oxygen generation, but low photosensitizing efficiencies, tumor resistance, and lack of spatial resolution limit their applicability. On the contrary, higher photosensitizing yields, versatile therapies, and a unique spatial resolution are available with engineered two-photon-sensitive organosilica particles that selectively impact tumors while healthy tissues remain untouched. Patients suffering pathologies such as retinoblastoma, breast, and skin cancers will greatly benefit from TPE-NIR ultrasensitive diagnosis and therapy. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Tale of two photons

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    A very profitable spinoff from electron- positron collisions is two-photon physics. Rather than the electron and positron interacting directly via an exchanged photon, two virtual (transient) photons, one from each particle, get tangled up. With new electron-positron colliders appearing on the scene, a topical meeting on two-photon physics - 'From DAPHNE to LEP 200 and beyond' - held from 2-4 February in Paris, in the premises of the Ministry of Higher Education and Research, was particularly timely. Some 60 physicists, both experimentalists and theorists, participated, with some thirty speakers

  13. Two Photon Distribution Amplitudes

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

    2008-01-01

    The factorization of the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region is demonstrated at the Born order and in the leading logarithmic approximation. The leading order two photon (generalized) distribution amplitudes exhibit a characteristic ln Q 2 behaviour and obey new inhomogeneous evolution equations

  14. Two-photon microscopy for chemical neuroscience.

    Science.gov (United States)

    Ellis-Davies, Graham C R

    2011-04-20

    Microscopes using non-linear excitation of chromophores with pulsed near-IR light can generate highly localized foci of molecules in the electronic singlet state that are concentrated in volumes of less than one femtoliter. The three-dimensional confinement of excitation arises from the simultaneous absorption of two IR photons of approximately half the energy required for linear excitation. Two-photon microscopy is especially useful for two types of interrogation of neural processes. First, uncaging of signaling molecules such as glutamate, as stimulation is so refined it can be used to mimic normal unitary synaptic levels. In addition, uncaging allows complete control of the timing and position of stimulation, so the two-photon light beam provides the chemical neuroscientist with an "optical conductor's baton" which can command synaptic activity at will. A second powerful feature of two-photon microscopy is that when used for fluorescence imaging it enables the visualization of cellular structure and function in living animals at depths far beyond that possible with normal confocal microscopes. In this review I provide a survey of the many important applications of two-photon microscopy in these two fields of neuroscience, and suggest some areas for future technical development.

  15. New photosensitizers for photodynamic therapy

    Science.gov (United States)

    Abrahamse, Heidi; Hamblin, Michael R.

    2016-01-01

    Photodynamic therapy (PDT) was discovered more than 100 years ago, and has since become a well-studied therapy for cancer and various non-malignant diseases including infections. PDT uses photosensitizers (PSs, non-toxic dyes) that are activated by absorption of visible light to initially form the excited singlet state, followed by transition to the long-lived excited triplet state. This triplet state can undergo photochemical reactions in the presence of oxygen to form reactive oxygen species (including singlet oxygen) that can destroy cancer cells, pathogenic microbes and unwanted tissue. The dual-specificity of PDT relies on accumulation of the PS in diseased tissue and also on localized light delivery. Tetrapyrrole structures such as porphyrins, chlorins, bacteriochlorins and phthalocyanines with appropriate functionalization have been widely investigated in PDT, and several compounds have received clinical approval. Other molecular structures including the synthetic dyes classes as phenothiazinium, squaraine and BODIPY (boron-dipyrromethene), transition metal complexes, and natural products such as hypericin, riboflavin and curcumin have been investigated. Targeted PDT uses PSs conjugated to antibodies, peptides, proteins and other ligands with specific cellular receptors. Nanotechnology has made a significant contribution to PDT, giving rise to approaches such as nanoparticle delivery, fullerene-based PSs, titania photocatalysis, and the use of upconverting nanoparticles to increase light penetration into tissue. Future directions include photochemical internalization, genetically encoded protein PSs, theranostics, two-photon absorption PDT, and sonodynamic therapy using ultrasound. PMID:26862179

  16. Two-photon induced collagen cross-linking in bioartificial cardiac tissue

    Science.gov (United States)

    Kuetemeyer, Kai; Kensah, George; Heidrich, Marko; Meyer, Heiko; Martin, Ulrich; Gruh, Ina; Heisterkamp, Alexander

    2011-08-01

    Cardiac tissue engineering is a promising strategy for regenerative therapies to overcome the shortage of donor organs for transplantation. Besides contractile function, the stiffness of tissue engineered constructs is crucial to generate transplantable tissue surrogates with sufficient mechanical stability to withstand the high pressure present in the heart. Although several collagen cross-linking techniques have proven to be efficient in stabilizing biomaterials, they cannot be applied to cardiac tissue engineering, as cell death occurs in the treated area. Here, we present a novel method using femtosecond (fs) laser pulses to increase the stiffness of collagen-based tissue constructs without impairing cell viability. Raster scanning of the fs laser beam over riboflavin-treated tissue induced collagen cross-linking by two-photon photosensitized singlet oxygen production. One day post-irradiation, stress-strain measurements revealed increased tissue stiffness by around 40% being dependent on the fibroblast content in the tissue. At the same time, cells remained viable and fully functional as demonstrated by fluorescence imaging of cardiomyocyte mitochondrial activity and preservation of active contraction force. Our results indicate that two-photon induced collagen cross-linking has great potential for studying and improving artificially engineered tissue for regenerative therapies.

  17. Influence of singlet oxygen (1O2) generated by a lipophilic photosensitizer (Pyropheophorbide-a, PPa) on membrane and firing properties of cultured hippocampus neurons

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Ogilby, Peter Remsen; Lambert, John D. C.

    2008-01-01

    During Photodynamic Therapy (PDT) of cancer, cells are killed by 1O2, which is generated in a photosensitized process. A photosensitizer (PS) is applied to the tissue and irradiated with light to form an exited molecule. This generates 1O2 from ground state oxygen, which then induce processes...

  18. Photodamage of mesotetraphenylporphyrin under one- and two-photon excitation

    International Nuclear Information System (INIS)

    Wen Yanan; Liu Yuqiang; Yang Zhenling; Yang Yanqiang; Guo Ximing

    2010-01-01

    Photoinduced damage behavior of mesotetraphenylporphyrin (TPP) under one- and two-photon excitation with femtosecond laser pulses is investigated in the present work. Quenching in the luminescent intensity is observed. Results suggest that laser irradiation on TPP mainly causes two simultaneously occurring photoprocesses: photodamage and formation of a porphine-type photoproduct. The damage rate exhibits a linear dependence on the incident light power in one-photon excitation, whereas in two-photon excitation, the power dependence of the damage rate turns out to be exponential. The photoproduct formed in one- and two-photon excitation is identical. This product, which is observed to possess superior photostability and two-photon absorbing ability compared with the original TPP sensitizer, is likely to be treated as a secondary photosensitizer in the activation process of photodynamic therapy (PDT). This work might be helpful for the drug evaluation in the practical application of PDT.

  19. Holographic monitoring of spatial distributions of singlet oxygen in water

    Science.gov (United States)

    Belashov, A. V.; Bel'tyukova, D. M.; Vasyutinskii, O. S.; Petrov, N. V.; Semenova, I. V.; Chupov, A. S.

    2014-12-01

    A method for monitoring spatial distributions of singlet oxygen in biological media has been developed. Singlet oxygen was generated using Radachlorin® photosensitizer, while thermal disturbances caused by nonradiative deactivation of singlet oxygen were detected by the holographic interferometry technique. Processing of interferograms yields temperature maps that characterize the deactivation process and show the distribution of singlet oxygen species.

  20. Simultaneous two-photon excitation of photodynamic therapy agents

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, E.A.; Fisher, W.G. [Oak Ridge National Lab., TN (United States)]|[Photogen, Inc., Knoxville, TN (United States); Partridge, W.P. [Oak Ridge National Lab., TN (United States); Dees, H.C. [Photogen, Inc., Knoxville, TN (United States); Petersen, M.G. [Univ. of Tennessee, Knoxville, TN (United States). College of Veterinary Medicine

    1998-01-01

    The spectroscopic and photochemical properties of several photosensitive compounds are compared using conventional single-photon excitation (SPE) and simultaneous two-photon excitation (TPE). TPE is achieved using a mode-locked titanium:sapphire laser, the near infrared output of which allows direct promotion of non-resonant TPE. Excitation spectra and excited state properties of both type 1 and type 2 photodynamic therapy (PDT) agents are examined.

  1. Clinical two-photon microendoscopy.

    Science.gov (United States)

    König, K; Ehlers, A; Riemann, I; Schenkl, S; Bückle, R; Kaatz, M

    2007-05-01

    Two-photon medical imaging has found its way into dermatology as an excellent method for noninvasive skin cancer detection without need of contrast agents as well as for in situ drug screening of topically-applied cosmetical and pharmaceutical components. There is an increasing demand to apply the multiphoton technology also for deep-tissue skin imaging as well as for intracorporal imaging. We report on the first clinical use of multiphoton endoscopes, in particular of a miniaturized rigid two-photon GRIN lens endoscope. The microendoscope was attached to the multiphoton tomograph DermaInspect and employed to detect the extracellular matrix proteins collagen and elastin in the human dermis of volunteers and patients with ulcera by in vivo second harmonic generation and in vivo two-photon autofluorescence. Copyright 2007 Wiley-Liss, Inc.

  2. Two-photon couplings of quarkonia with arbitrary JPC

    International Nuclear Information System (INIS)

    Barnes, T.; Tennessee Univ., Knoxville, TN

    1992-01-01

    We present theoretical results for the two-photon widths of relativistic quarkonium states with arbitrary angular momenta. These relativistic formulas are required to obtain reasonable agreement with the absolute scale of quarkonium decay rates to two photons, and have previously only been derived for spin-singlet q bar q states. We also evaluate these formulas numerically for ell ≤3 q = u, d states in a Coulomb-plus-linear q bar q potential model. Light-quark higher-ell and radially-excited q bar q states should be observable experimentally, as their two-photon widths are typically found to be ∼1 KeV. The radially-excited 1 S 0 higher-mass quarkonium states such as c bar c and b bar b should also be observable in γγ, but orbitally-excited c bar c states with ell>1 and b bar b states with ell>0 are expected to have very small two-photon widths. The helicity structure of the higher-ell q bar q couplings is predicted to be nontrivial, with both λ=0 and λ=2γγ final states contributing significantly; these results may be useful as signatures for q bar q states

  3. Two-photon-induced cycloreversion reaction of chalcone photodimers

    Science.gov (United States)

    Träger, J.; Härtner, S.; Heinzer, J.; Kim, H.-C.; Hampp, N.

    2008-04-01

    The photocleavage reaction of chalcone photodimers has been studied using a two-photon process. For this purpose, a novel chalcone dimer has been synthesized as a low molecular weight model substance for polymer bound chalcones and its photochemistry triggered by two-photon-absorption (2PA) has been investigated using a pulsed frequency-doubled Nd:YAG-laser. The 2PA-induced cycloreversion reaction selectively leads to the cleavage of the chalcone photodimers resulting in the formation of monomeric chalcone molecules. Hence, as an application chalcones can be used as a photosensitive linker which can be cleaved beyond an UV-absorbing barrier. The 2PA cross section of the chalcone photodimer was determined to be of 1.1 × 10 -49 cm 4 s photon -1 (11 GM).

  4. Reversible Photochemical Control of Singlet Oxygen Generation Using Diarylethene Photochromic Switches

    NARCIS (Netherlands)

    Hou, Lili; Zhang, Xiaoyan; Pijper, Thomas C.; Browne, Wesley R.; Feringa, Bernard

    2014-01-01

    Reversible noninvasive control over the generation of singlet oxygen is demonstrated in a bicomponent system comprising a diarylethene photochromic switch and a porphyrin photosensitizer by selective irradiation at distinct wavelengths. The efficient generation of singlet oxygen by the

  5. Holographic Two-Photon Induced Photopolymerization

    Data.gov (United States)

    Federal Laboratory Consortium — Holographic two-photon-induced photopolymerization (HTPIP) offers distinct advantages over conventional one-photon-induced photopolymerization and current techniques...

  6. A genetically targetable near-infrared photosensitizer.

    Science.gov (United States)

    He, Jianjun; Wang, Yi; Missinato, Maria A; Onuoha, Ezenwa; Perkins, Lydia A; Watkins, Simon C; St Croix, Claudette M; Tsang, Michael; Bruchez, Marcel P

    2016-03-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species that can be used for functional manipulation of living cells, including protein inactivation, targeted-damage introduction and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer inside the cell. We describe a genetically encoded fluorogen-activating protein (FAP) that binds a heavy atom-substituted fluorogenic dye, forming an 'on-demand' activated photosensitizer that produces singlet oxygen and fluorescence when activated with near-infrared light. This targeted and activated photosensitizer (TAPs) approach enables protein inactivation, targeted cell killing and rapid targeted lineage ablation in living larval and adult zebrafish. The near-infrared excitation and emission of this FAP-TAPs provides a new spectral range for photosensitizer proteins that could be useful for imaging, manipulation and cellular ablation deep within living organisms.

  7. Charm production in two-photon collisions

    International Nuclear Information System (INIS)

    Linde, F.L.

    1988-01-01

    The analysis focuses on the production of charmonium resonances η c , χ 0 and χ 2 in two-photon interactions. The measurement of the inclusive production of charged D* mesons is described. 97 refs.; 54 figs.; 15 tabs

  8. Two-Photon Physics in Hadronic Processes

    Energy Technology Data Exchange (ETDEWEB)

    Carl Carlson; Marc Vanderhaeghen

    2007-11-01

    Two-photon exchange contributions to elastic electron-scattering are reviewed. The apparent discrepancy in the extraction of elastic nucleon form factors between unpolarized Rosenbluth and polarization transfer experiments is discussed, as well as the understanding of this puzzle in terms of two-photon exchange corrections. Calculations of such corrections both within partonic and hadronic frameworks are reviewed. In view of recent spin-dependent electron scattering data, the relation of the two-photon exchange process to the hyperfine splitting in hydrogen is critically examined. The imaginary part of the two-photon exchange amplitude as can be accessed from the beam normal spin asymmetry in elastic electron-nucleon scattering is reviewed. Further extensions and open issues in this field are outlined.

  9. Exclusive hadron production in two photon reactions

    International Nuclear Information System (INIS)

    Poppe, M.

    1986-02-01

    This paper summarises experimental results on exclusive hadron production in two photon collisions at electron positron storage rings and attempts some interpretation. Experimental know how is described and new suggestions are made for future analyses. New model calculations on resonance form factors and pair production amplitudes are presented. The two photon vertex is decomposed such that experiments can be parameterised with the minimal number of free parameters. Selection rules for off shell photon collisions are given in addition to Yang's theorems. (orig.)

  10. Determining the quark charges by one and two photon processes

    International Nuclear Information System (INIS)

    Janah, A.

    1982-01-01

    Testable predictions are presented, which may be used to decide between the gauge theories of integer and fractionally charged quarks (icq and fcq). Two distinctive features of icq are exploited, namely (a) presence of color non-singlet components in weak and electromagnetic currents and (b) possible liberation of color non-singlet states above a threshold energy. Consequences are sought in lepton-hadron interaction processes, taking into account the known color-suppression effect. Single photon/weak-boson processes such as nuN → nuX distinguish between icq and fcq only above color-threshold. Experimental consequences of color-liberation in the above process are obtained. It is found that the gluon-parton contribution survives color-suppression to produce a significant rise in the structure functions when color-threshold is exceeded. Two-photon processes such as e + e - → e + e - + 2 jets distinguish between the two theories even below color threshold. To obtain the icq predictions for this process, one must take into account (a) the (momentum-dependent) color suppression and (b) the added contribution from pair production of charged gluons

  11. Singlet Fission

    Czech Academy of Sciences Publication Activity Database

    Smith, M. B.; Michl, Josef

    2010-01-01

    Roč. 110, č. 11 (2010), s. 6891-6936 ISSN 0009-2665 Grant - others:Department of Energy(US) DE- FG36 -08GO18017 Institutional research plan: CEZ:AV0Z40550506 Keywords : solar energy conversion * photovoltaics * singlet fission Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 33.033, year: 2010

  12. Two-photon excitation of argon

    International Nuclear Information System (INIS)

    Pindzola, P.S.; Payne, M.C.

    1982-01-01

    The authors calculate two photon excitation parameters for various excited states of argon assuming the absorption of near resonance broad-bandwidth laser radiation. Results are given for the case of two photons absorbed for the same laser beam as well as the case of absorbing photons of different frequency from each of two laser beams. The authors use multiconfiguration Hartree-Fock wave functions to evaluate the second-order sums over matrix elements. Various experimental laser schemes are suggested for the efficient excitation and subsequent ionization of argon

  13. Two-photon excitation STED microscopy.

    Science.gov (United States)

    Moneron, Gael; Hell, Stefan W

    2009-08-17

    We report sub-diffraction resolution in two-photon excitation (TPE) fluorescence microscopy achieved by merging this technique with stimulated-emission depletion (STED). We demonstrate an easy-to-implement and promising laser combination based on a short-pulse laser source for two-photon excitation and a continuous-wave (CW) laser source for resolution enhancement. Images of fluorescent nanoparticles and the immunostained transcription regulator NF kappaB in mammalian cell nuclei exhibit resolutions of barrier. (c) 2009 Optical Society of America

  14. Transition dynamics in two-photon ionisation

    Science.gov (United States)

    Vacher, Morgane; Gaillac, Romain; Maquet, Alfred; Taïeb, Richard; Caillat, Jérémie

    2017-11-01

    We review various aspects of photoemission dynamics in the case of two-photon ionisation. We first recall the definition of a transition phase specific to two-photon transitions. Numerical experiments on model atoms are used to show how the group delay associated with the transition phase is actually representative of the early dynamics of the detected photoelectron wave packets. Then we address the question of measuring these transition delays using a standard interferometric technique of experimental attosecond physics, so-called rabbit. Finally, we outline different reinterpretations of rabbit giving access to the more fundamental scattering dynamics affecting any photoemission processes.

  15. Photosensitized oxidation of DNA and its components

    International Nuclear Information System (INIS)

    Decarroz, Chantal.

    1982-09-01

    Chemical changes in DNA components during the photodynamic effect are responsible for Mutagenic and carcinogenic phenomena. Basically two competitive mechanisns involving respectively a charge transfer (type I) and singlet oxygen (type II) are implicated in reactions photo-sensitized by different agents (acridines, phenothiazines, porphyrins, flavins, psoralenes...). A study of the photosensitized oxidation of DNA itself was approached through characterization of the main final products in the case of purine nucleosides. Methyl-2 naphthoquinone - 1,4 (vitamin K 3 ) displays a special photosensitization mechanism involving a cation radical type of intermediary [fr

  16. Developments in PDT Sensitizers for Increased Selectivity and Singlet Oxygen Production

    Directory of Open Access Journals (Sweden)

    Nahid Mehraban

    2015-07-01

    Full Text Available Photodynamic therapy (PDT is a minimally-invasive procedure that has been clinically approved for treating certain types of cancers. This procedure takes advantage of the cytotoxic activity of singlet oxygen (1O2 and other reactive oxygen species (ROS produced by visible and NIR light irradiation of dye sensitizers following their accumulation in malignant cells. The main two concerns associated with certain clinically-used PDT sensitizers that have been influencing research in this arena are low selectivity toward malignant cells and low levels of 1O2 production in aqueous media. Solving the selectivity issue would compensate for photosensitizer concerns such as dark toxicity and aggregation in aqueous media. One main approach to enhancing dye selectivity involves taking advantage of key methods used in pharmaceutical drug delivery. This approach lies at the heart of the recent developments in PDT research and is a point of emphasis in the present review. Of particular interest has been the development of polymeric micelles as nanoparticles for delivering hydrophobic (lipophilic and amphiphilic photosensitizers to the target cells. This review also covers methods employed to increase 1O2 production efficiency, including the design of two-photon absorbing sensitizers and triplet forming cyclometalated Ir(III complexes.

  17. A Comparison of Singlet Oxygen Explicit Dosimetry (SOED and Singlet Oxygen Luminescence Dosimetry (SOLD for Photofrin-Mediated Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Michele M. Kim

    2016-12-01

    Full Text Available Accurate photodynamic therapy (PDT dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED model has been developed for in vivo purposes. It involves the measurement of the key components in PDT—light fluence (rate, photosensitizer concentration, and ground-state oxygen concentration ([3O2]—to calculate the amount of reacted singlet oxygen ([1O2]rx, the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime (τΔ and τt, for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [1O2]rx was compared to SOED-calculated [1O2]rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [1O2]rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM PDT protocol by using a conversion formula.

  18. N'-formylkynurenine-photosensitized inactivation of bacteriophage

    International Nuclear Information System (INIS)

    Walrant, P.; Santus, R.; Redpath, J.L.; Pileni, M.P.

    1976-01-01

    Measurements have been made of the sensitizing properties of N'-formylkynurenine (FK) on bacteriophages, as part of a wider study of FK photosensitization of systems which have both protein and DNA components. Suspensions of bacteriophages T 6 and T 7 were near-U.V. (lambda > 320 nm) irradiated in solutions saturated with either O 2 or He in the presence of 5 x 10 -4 M FK. The survival curves obtained demonstrated that FK can act as a photosensitizer for biological inactivation. The involvement of singlet oxygen as one factor in this FK sensitized inactivation was clearly demonstrated by the increased rate of inactivation when the phage were suspended in O 2 -saturated D 2 O, in place of water, during irradiation. The complex mechanism of phage inactivation must involve direct interaction between excited FK and substrate, as well as singlet oxygen. FK is therefore a new natural photosensitizer of significance in cell photochemistry induced by sunlight. (U.K.)

  19. Probing two-photon exchange with OLYMPUS

    International Nuclear Information System (INIS)

    Kohl, M.

    2014-01-01

    Two-photon exchange is believed to be responsible for the discrepancies in the proton electric to magnetic form factor ratio found with the Rosenbluth and polarization transfer methods. If this explanation is correct, one expects significant differences in the lepton-proton cross sections between positrons and electrons. The OLYMPUS experiment at DESY in Hamburg, Germany was designed to measure the ratio of unpolarized positron-proton and electron-proton elastic scattering cross sections over a wide kinematic range with high precision, in order to quantify the effect of two-photon exchange. The experiment used intense beams of electrons and positrons stored in the DORIS ring at 2.0 GeV interacting with an internal windowless hydrogen gas target. The current status of OLYMPUS will be discussed. (authors)

  20. Two-photon cooling of magnesium atoms

    DEFF Research Database (Denmark)

    Malossi, N.; Damkjær, S.; Hansen, P. L.

    2005-01-01

    A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)S01¿(3s3p)P11 at 285.2nm followed by the (3s3p)P11¿(3s3d)D21 transition at 880.7nm . For the ladder system quantum coherence effects may become important. Combined...... with the basic two-level Doppler cooling process this allows for reduction of the atomic sample temperature by more than a factor of 10 over a broad frequency range. First experimental evidence for the two-photon cooling process is presented and compared to model calculations. Agreement between theory...... and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed....

  1. Two-photon spin generation and detection

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)

    2009-02-21

    A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay ({Delta}t), lattice temperature (T{sub L}), doping density (n) as well as of the excess photon energy {Delta}E{sub 2{omega}}= {h_bar}2{omega} - E{sub g}, where E{sub g} is the band gap energy. P is found to be decayed with {Delta}t and enhanced with the decrease in T{sub L} or the increase in n. It is also found that P decreases with the increase in {Delta}E{sub 2{omega}}and depolarizes rapidly for {Delta}E{sub 2{omega}}> {Delta}E{sub SO}, where {Delta}E{sub SO} is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

  2. Two-photon spin generation and detection

    International Nuclear Information System (INIS)

    Miah, M Idrish

    2009-01-01

    A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay (Δt), lattice temperature (T L ), doping density (n) as well as of the excess photon energy ΔE 2ω = ℎ2ω - E g , where E g is the band gap energy. P is found to be decayed with Δt and enhanced with the decrease in T L or the increase in n. It is also found that P decreases with the increase in ΔE 2ω and depolarizes rapidly for ΔE 2ω > ΔE SO , where ΔE SO is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

  3. Elsinochrome A photosensitizers: Alternative drugs for photodynamic therapy

    Directory of Open Access Journals (Sweden)

    Tinghui Li

    2015-01-01

    Full Text Available Photodynamic therapy (PDT has already been a multifunctional modality for various tumors and nontumorous diseases. However, the development of photosensitizers is relatively delayed, compared with the tremendous progress in laser technology. Elsinochrome A (EA, a perylenequinonoid pigment from China, has all the typical advantages of perylenequinones. Moreover, singlet oxygen quantum yield of EA is superior to other kinds of photosensitizers and EA could be artificially biosynthesized at present, which make it an alternative candidate for PDT. In this review, the photophysics, photochemistry, photobiology and chemical or biological syntheses of EA photosensitizers are briefly presented. Besides, the future prospects of EA photosensitizers are also proposed.

  4. Two-photon physics at LEP

    International Nuclear Information System (INIS)

    Ginzburg, I.F.

    1988-01-01

    The two-photon production of hadrons in e + e - collisions e + e - →e + e - h from which the γγ→h cross sections are extracted is discussed. The common features of these processes are: hadrons move, as a rule, along e + e - beam axis, their total transverse momentum K perpendicular or perpendicular to is small; the total hadron energy is usually less than √S/2. Physical problems of soft processes, exotics, hard processes, semihard processes are considered. New possibilities of LEP, the most interesting and real are presented

  5. Two-photon polymerization of an epoxy-acrylate resin material system

    International Nuclear Information System (INIS)

    Winfield, R.J.; O'Brien, S.

    2011-01-01

    Improved material systems are of great interest in the development of two-photon polymerization techniques for the fabrication of three dimensional micro- and nano-structures. The properties of the photosensitive resin are important in the realisation of structures with submicron dimensions. In this study investigation of a custom organic resin, cross-linked by a two-photon induced process, using a femtosecond Ti:sapphire laser, is described. A structural, optical and mechanical analysis of the optimised material is presented. The influence of both material system and laser processing parameters on achievable micro-structure and size is presented as are representative structures. Parameters include: laser power, photo-initiator concentration and material composition.

  6. Resonant production in two photon collisions

    International Nuclear Information System (INIS)

    Butler, F.

    1988-12-01

    Using 220 picobarn/sup /minus/1/ of data collected by the Mark II detector at PEP, we have measured the width of the /eta/' for quasi real photons. The width is separately measured in the three reactions e + e/sup /minus// → e + e/sup /minus///eta/ 0 π + π/sup /minus//; /eta/ 0 → γγ, e + e/sup /minus// → e + e/sup /minus///eta/ 0 π + π/sup /minus//; /eta/ 0 → π + π/sup /minus//(π 0 ,γ) and e + e/sup /minus// → e + e/sup /minus///rho/ 0 γ, giving a statistically weighted average two-photon width of Γ/sub /eta/'→γγ/ = 5. 21+-0.28 keV. As a by-product of the measurement of Γ/sub /eta/'→γγ/ using the decay mode /eta/' → /rho/γ, we also measured a two-photon decay width for the a 2 (1320) of Γ/sub a 2(1320)→γγ/ = 1.17+-0. 15+-0.25 keV. 47 refs., 50 figs., 8 tabs

  7. Photosensitized oxidation of unsaturated polymers

    Science.gov (United States)

    Golub, M. A.

    1979-01-01

    The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1.

  8. On the kinematics of the two-photon Cherenkov effect

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.; Stepanovskij, Yu.P.

    2003-01-01

    We study the kinematics of the two-photon Cherenkov effect. In the general case, the emission angles of two photons satisfy certain inequalities and the corresponding radiation intensities are rather diffused. In special cases, when the above inequalities reduce to equalities, the emission angles of two photons are fixed and the corresponding radiation intensities should have sharp maxima at these angles. This makes easier the experimental study of the two-photon Cherenkov effect

  9. Microsphere imaging with confocal microscopy and two photon microscopy

    International Nuclear Information System (INIS)

    Chun, Hyung Su; An, Kyung Won; Lee, Jai Hyung

    2002-01-01

    We have acquired images of polystyrene and fused-silica microsphere by using conventional optical microscopy, confocal microscopy and two-photon microscopy, and performed comparative analysis of these images. Different from conventional optical microscopy, confocal and two-photon microscopy had good optical sectioning capability. In addition, confocal microscopy and two-photon microscopy had better lateral resolution than conventional optical microscopy. These results are attributed to confocality and nonlinearity of confocal microscopy and two photon microscopy, respectively.

  10. Singlet oxygen quenching by oxygen in tetraphenyl-porphyrin solutions

    International Nuclear Information System (INIS)

    Dedic, Roman; Korinek, Miloslav; Molnar, Alexander; Svoboda, Antonin; Hala, Jan

    2006-01-01

    Time-resolved measurement of singlet oxygen infrared phosphorescence is a powerful tool for determination of quantum yields and kinetics of its photosensitization. This technique was employed to investigate in detail the previously observed effect of singlet oxygen quenching by oxygen. The question whether the singlet oxygen is quenched by oxygen in ground or in excited state was addressed by study of two complementary dependencies of singlet oxygen lifetimes: on dissolved oxygen concentration and on excitation intensity. Oxygen concentration dependence study of meso-tetra(4-sulphonato)phenylporphyrin (TPPS 4 ) phosphorescence kinetics showed linearity of the dependence of TPPS 4 triplet state rate-constant. Corresponding bimolecular quenching constant of (1.5±0.1)x10 9 l/mol s was obtained. On the other hand, rate constants of singlet oxygen depopulation exhibit nonlinear dependence on oxygen concentration. Comparison of zero oxygen concentration-extrapolated value of singlet oxygen lifetime of (6.5±0.4) μs to (3.7±0.1) μs observed under air-saturated conditions indicates importance of the effect of quenching of singlet oxygen by oxygen. Upward-sloping dependencies of singlet oxygen depopulation rate-constant on excitation intensity evidence that singlet oxygen is predominantly quenched by oxygen in excited singlet state

  11. Two photon annihilation operators and squeezed vacuum

    Science.gov (United States)

    Roy, Anil K.; Mehta, C. L.; Saxena, G. M.

    1993-01-01

    Inverses of the harmonic oscillator creation and annihilation operators by their actions on the number states are introduced. Three of the two photon annihilation operators, viz., a(sup +/-1)a, aa(sup +/-1), and a(sup 2), have normalizable right eigenstates with nonvanishing eigenvalues. The eigenvalue equation of these operators are discussed and their normalized eigenstates are obtained. The Fock state representation in each case separates into two sets of states, one involving only the even number states while the other involving only the odd number states. It is shown that the even set of eigenstates of the operator a(sup +/-1)a is the customary squeezed vacuum S(sigma) O greater than.

  12. Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Perrier, Marine [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Gary-Bobo, Magali [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Lartigue, Lenaiec; Brevet, David [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Morere, Alain; Garcia, Marcel [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Maillard, Philippe [Universite Paris-Sud, UMR 176 CNRS, Institut Curie (France); Raehm, Laurence; Guari, Yannick, E-mail: yannick.guari@um2.fr; Larionova, Joulia; Durand, Jean-Olivier, E-mail: durand@univ-montp2.fr [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Mongin, Olivier [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, CNRS UMR 6226 (France); Blanchard-Desce, Mireille [Universite Bordeaux, Institut des Sciences Moleculaires, UMR CNRS 5255 (France)

    2013-05-15

    An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

  13. Targeted oxidation of Torpedo californica acetylcholinesterase by singlet oxygen: identification of N-formylkynurenine tryptophan derivatives within the active-site gorge of its complex with the photosensitizer methylene blue.

    Science.gov (United States)

    Triquigneaux, Mathilde M; Ehrenshaft, Marilyn; Roth, Esther; Silman, Israel; Ashani, Yakov; Mason, Ronald P; Weiner, Lev; Deterding, Leesa J

    2012-11-15

    The principal role of AChE (acetylcholinesterase) is termination of impulse transmission at cholinergic synapses by rapid hydrolysis of the neurotransmitter acetylcholine. The active site of AChE is near the bottom of a long and narrow gorge lined with aromatic residues. It contains a CAS (catalytic 'anionic' subsite) and a second PAS (peripheral 'anionic' site), the gorge mouth, both of which bind acetylcholine via π-cation interactions, primarily with two conserved tryptophan residues. It was shown previously that generation of (1)O(2) by illumination of MB (Methylene Blue) causes irreversible inactivation of TcAChE (Torpedo californica AChE), and suggested that photo-oxidation of tryptophan residues might be responsible. In the present study, structural modification of the TcAChE tryptophan residues induced by MB-sensitized oxidation was investigated using anti-N-formylkynurenine antibodies and MS. From these analyses, we determined that N-formylkynurenine derivatives were specifically produced from Trp(84) and Trp(279), present at the CAS and PAS respectively. Peptides containing these two oxidized tryptophan residues were not detected when the competitive inhibitors, edrophonium and propidium (which should displace MB from the gorge) were present during illumination, in agreement with their efficient protection against the MB-induced photo-inactivation. Thus the bound MB elicited selective action of (1)O(2) on the tryptophan residues facing on to the water-filled active-site gorge. The findings of the present study thus demonstrate the localized action and high specificity of MB-sensitized photo-oxidation of TcAChE, as well as the value of this enzyme as a model system for studying the mechanism of action and specificity of photosensitizing agents.

  14. Targeted oxidation of Torpedo californica acetylcholinesterase by singlet oxygen: Identification of N-formylkynurenine tryptophan derivatives within the active-site gorge of its complex with the photosensitizer methylene blue

    Science.gov (United States)

    Triquigneaux, Mathilde M.; Ehrenshaft, Marilyn; Roth, Esther; Silman, Israel; Ashani, Yakov; Mason, Ronald P.; Weiner, Lev; Deterding, Leesa J.

    2013-01-01

    Synopsis The principal role of acetylcholinesterase (AChE) is termination of impulse transmission at cholinergic synapses by rapid hydrolysis of the neurotransmitter acetylcholine. The active site of AChE is near the bottom of a long and narrow gorge lined with aromatic residues. It contains a catalytic ‘anionic’ subsite (CAS) and a second peripheral ‘anionic’ site (PAS), the gorge mouth, both of which bind acetylcholine via π-cation interactions, primarily with two conserved tryptophans (Trps). It was earlier shown that generation of 1O2 by illumination of methylene blue (MB) causes irreversible inactivation of Torpedo californica AChE (TcAChE), and suggested that photo-oxidation of Trps might be responsible. In the present study, structural modification of the TcAChE Trps induced by MB-sensitized oxidation was investigated using anti-N-formylkynurenine antibodies and mass spectrometry. From these analyses, we determined that N-formylkynurenine derivatives were specifically produced from Trp 84 and Trp 279 – present at the CAS and PAS, respectively. Peptides containing these two oxidized Trp residues were not detected when the competitive inhibitors, edrophonium and propidium (which should displace MB from the gorge) were present during illumination, in agreement with their efficient protection against the MB-induced photo-inactivation. Thus, the bound MB elicited selective action of 1O2 on Trp residues facing onto the water-filled active-site gorge. Our findings thus demonstrate the localized action and high specificity of MB-sensitized photo-oxidation of TcAChE, as well as the value of this enzyme as a model system for studying the mechanism of action and specificity of photosensitizing agents. PMID:22888904

  15. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    International Nuclear Information System (INIS)

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-01-01

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D 6h point group symmetry versus ovalene with D 2h symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D 6h group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D 2h ovalene but not in those with D 6h symmetry

  16. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    Energy Technology Data Exchange (ETDEWEB)

    Aryanpour, Karan [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Shukla, Alok [Department of Physics, Indian Institute of Technology, Powai, Mumbai 400076 (India); Mazumdar, Sumit [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States)

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D{sub 6h} point group symmetry versus ovalene with D{sub 2h} symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D{sub 6h} group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D{sub 2h} ovalene but not in those with D{sub 6h} symmetry.

  17. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: a peculiar role of geometry.

    Science.gov (United States)

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D(6h) point group symmetry versus ovalene with D(2h) symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D(6h) group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D(2h) ovalene but not in those with D(6h) symmetry.

  18. Two-photon decay in heavy atoms and ions

    International Nuclear Information System (INIS)

    Mokler, P.H.; Dunford, R.W

    2003-08-01

    We review the status of and comment on current developments in the field of two-photon decay in atomic physics research. Recent work has focused on two-photon decays in highly-charged ions and two-photon decay of inner-shell vacancies in heavy neutral atoms. We emphasize the importance of measuring the shape of the continuum emission in two-photon decay as a probe of relativistic effects in the strong central fields found in heavy atomic systems. New experimental approaches and their consequences will be discussed. (orig.)

  19. Resonance production in two-photon interactions

    International Nuclear Information System (INIS)

    Roe, N.A.

    1989-02-01

    Resonance production in two-photon interactions is studied using data collected with the ASP detector at the PEP e + e/sup /minus// storage ring located at the Stanford Linear Accelerator Center. The ASP detector is a non-magnetic lead-glass calorimeter constructed from 632 lead-glass bars. It covers 94% of 4π in solid angle, extending to within 20/degree/ of the beamline. Lead-scintillator calorimeters extend the coverage to within 21 mr of the beamline on both sides. Energy resolution of √E/10%, where E is the energy is GeV, is achieved for electrons and photons in the lead-glass calorimeter, and particle trajectories are reconstructed with high efficiency. A total luminosity of 108 pb/sup /minus/1/ was collected with the ASP detector at a center-of-mass energy of 29 GeV. The observed process is e + e/sup /minus// → e + e/sup /minus//γ*γ* → e + e/sup /minus//X, is a pseudoscalar resonance (J/sup PC/ = 0/sup /minus/+/) and γ* is a virtual (mass /ne/ 0) photon. The outgoing electrons scatter down the beampipe and are not detected. The observed resonances are the /eta/ and /eta/' mesons, with masses of 549 and 958 MeV, respectively. They are detected in the γγ decay mode; a total of 2380 +- 49 /eta/ → γγ and 568 +- 26 /eta/' → γγ events are observed. From the number of events, the detection efficiency, and the calculated production cross sections the radiative widths, Γ/sub γγ/, of the /eta/ and /eta/' were measured and found to be: Γ/sub γγ/(/eta/) = .481 +- .010 +- .047keV and Γ/sub γγ/(/eta/') = 4.71 +- .22 +- .70keV. These results are in good agreement with the world average values. 67 refs., 42 figs., 20 tabs

  20. Resonance production in two-photon interactions

    Energy Technology Data Exchange (ETDEWEB)

    Roe, N.A.

    1989-02-01

    Resonance production in two-photon interactions is studied using data collected with the ASP detector at the PEP e/sup +/e/sup /minus// storage ring located at the Stanford Linear Accelerator Center. The ASP detector is a non-magnetic lead-glass calorimeter constructed from 632 lead-glass bars. It covers 94% of 4..pi.. in solid angle, extending to within 20/degree/ of the beamline. Lead-scintillator calorimeters extend the coverage to within 21 mr of the beamline on both sides. Energy resolution of ..sqrt..E/10%, where E is the energy is GeV, is achieved for electrons and photons in the lead-glass calorimeter, and particle trajectories are reconstructed with high efficiency. A total luminosity of 108 pb/sup /minus/1/ was collected with the ASP detector at a center-of-mass energy of 29 GeV. The observed process is e/sup +/e/sup /minus// ..-->.. e/sup +/e/sup /minus//..gamma..*..gamma..* ..-->.. e/sup +/e/sup /minus//X, is a pseudoscalar resonance (J/sup PC/ = 0/sup /minus/+/) and ..gamma..* is a virtual (mass /ne/ 0) photon. The outgoing electrons scatter down the beampipe and are not detected. The observed resonances are the /eta/ and /eta/' mesons, with masses of 549 and 958 MeV, respectively. They are detected in the ..gamma gamma.. decay mode; a total of 2380 +- 49 /eta/ ..-->.. ..gamma gamma.. and 568 +- 26 /eta/' ..-->.. ..gamma gamma.. events are observed. From the number of events, the detection efficiency, and the calculated production cross sections the radiative widths, GAMMA/sub ..gamma gamma../, of the /eta/ and /eta/' were measured and found to be: GAMMA/sub ..gamma gamma../(/eta/) = .481 +- .010 +- .047keV and GAMMA/sub ..gamma gamma../(/eta/') = 4.71 +- .22 +- .70keV. These results are in good agreement with the world average values. 67 refs., 42 figs., 20 tabs.

  1. Precision two-photon spectroscopy of alkali elements

    Indian Academy of Sciences (India)

    2014-07-18

    Jul 18, 2014 ... In this paper, we have briefly reviewed the work on two-photon spectroscopy of alkali elements and its applications. The technique of Doppler-free two-photon spectroscopy is briefly summarized. A review of various techniques adopted for measuring absolute frequencies of the atomic transitions and ...

  2. Precision two-photon spectroscopy of alkali elements

    Indian Academy of Sciences (India)

    Doppler-free two-photon spectroscopy uses two counterpropagating laser beams for exci- tation. In this technique, simultaneous absorption of two photons drives the atomic transition. If the atom absorbs one photon from each of the counterpropagating beam, then the Doppler shifts cancel in the rest frame of the atom.

  3. Systemic reduction of rice blast by means of photosensitizers

    Science.gov (United States)

    Acquired disease resistance of plants may be induced by exogenous reactive oxygen species or their sources. Certain compounds (photosensitizers) produce ROS at the expense of light energy. This study used photodynamic dyes bengal rose and methylene blue, which yield singlet oxygen, and mercaptopyrid...

  4. Singlet Oxygen Sensor Green: Photochemical Behavior in Solution and in a Mammalian Cell

    DEFF Research Database (Denmark)

    Gollmer, Anita; Arnbjerg, Jacob; Blaikie, Frances Helen

    2011-01-01

    The development of efficient and selective luminescent probes for reactive oxygen species, particularly for singlet molecular oxygen, is currently of great importance. In this study, the photochemical behavior of Singlet Oxygen Sensor Green® (SOSG), a commercially available fluorescent probe...... of the reaction between SOSG and singlet oxygen is, itself, an efficient singlet oxygen photosensitizer. Second, SOSG appears to efficiently bind to proteins which, in turn, can influence uptake by a cell as well as behavior in the cell. As such, incorrect use of SOSG can yield misleading data on yields...

  5. Two-photon quantum Rabi model with superconducting circuits

    Science.gov (United States)

    Felicetti, S.; Rossatto, D. Z.; Rico, E.; Solano, E.; Forn-Díaz, P.

    2018-01-01

    We propose a superconducting circuit to implement a two-photon quantum Rabi model in a solid-state device, where a qubit and a resonator are coupled by a two-photon interaction. We analyze the input-output relations for this circuit in the strong-coupling regime and find that fundamental quantum-optical phenomena are qualitatively modified. For instance, two-photon interactions are shown to yield a single- or two-photon blockade when a pumping field is either applied to the cavity mode or to the qubit, respectively. In addition, we derive an effective Hamiltonian for perturbative ultrastrong two-photon couplings in the dispersive regime, where two-photon interactions introduce a qubit-state-dependent Kerr term. Finally, we analyze the spectral collapse of the multiqubit two-photon quantum Rabi model and find a scaling of the critical coupling with the number of qubits. Using realistic parameters with the circuit proposed, three qubits are sufficient to reach the collapse point.

  6. Two-photon processes in highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Jahrsetz, Thorsten

    2015-03-05

    Two-photon processes are atomic processes in which an atom interacts simultaneously with two photons. Such processes describe a wide range of phenomena, such as two-photon decay and elastic or inelastic scattering of photons. In recent years two-photon processes involving highly charged heavy ions have become an active area of research. Such studies do not only consider the total transition or scattering rates but also their angular and polarization dependence. To support such examinations in this thesis I present a theoretical framework to describe these properties in all two-photon processes with bound initial and final states and involving heavy H-like or He-like ions. I demonstrate how this framework can be used in some detailed studies of different two-photon processes. Specifically a detailed analysis of two-photon decay of H-like and He-like ions in strong external electromagnetic fields shows the importance of considering the effect of such fields for the physics of such systems. Furthermore I studied the elastic Rayleigh as well as inelastic Raman scattering by heavy H-like ions. I found a number of previously unobserved phenomena in the angular and polarization dependence of the scattering cross-sections that do not only allow to study interesting details of the electronic structure of the ion but might also be useful for the measurement of weak physical effects in such systems.

  7. Towards photodynamic therapy with ionizing radiation: nanoparticle-mediated singlet oxygen generation (Conference Presentation)

    Science.gov (United States)

    Clement, Sandhya; Deng, Wei; Camilleri, Elizabeth; Wilson, Brian; Goldys, Ewa

    2016-03-01

    Photodynamic therapy (PDT) is a clinically approved method for the treatment of cancer by using singlet oxygen, a highly reactive oxygen generated from a photosensitizer drug upon photoactivation. Limited light penetration depth into to the tissue means that PDT is unsuitable for deep tissue cancer treatments. This can be overcome by using X-ray /gamma rays activated nanoparticles able to trigger the photosensitizer drug and generate singlet oxygen. Additionally, inorganic nanoparticles interact more strongly with X and/or gamma rays than the tissue, allowing to concentrate the effects of radiation near nanoparticle surface and they can also be molecularly targeted to cancer cells. In this work we synthesized and characterized CeF3 nanoparticles, a well-known scintillator material. The nanoparticles were conjugated with Verteporfin, a photosensitizer drug by electrostatic interaction. We assessed the performance of CeF3 and the conjugates to generate singlet oxygen exposed to X-ray radiation. The X-ray singlet oxygen quantum yield of the nanoparticle-photosensitizer system was accurately quantified for the first time. This provided realistic estimates of the singlet oxygen dose taking into consideration the dose partition of the radiation between CeF3 and the tissue. Furthermore, we investigated gold nanoparticle-photosensitizer systems. We confirmed that pure gold nanoparticles itself generate singlet oxygen which is attributed to plasmonic effects. We found enhanced singlet oxygen generation from gold-Rose Bengal conjugates and gold nanorod-verteporfin conjugates. These singlet-oxygen-generating nanomaterials add a new dimension to radiation-assisted PDT.

  8. Rapid Fabrication of Three-Dimensional Woodpile Photonic Crystals by Means of Two-Photon Photopolymerization

    Science.gov (United States)

    Zhou, Ming; Kong, Jun-Jie; Yang, Hai-Feng; Yan, Feng; Cai, Lan

    2007-11-01

    Two-photon photopolymerization (TPP) of femtosecond laser is a promising method to fabricate three-dimensional woodpile photonic crystals (PCs). We build micro-fabrication system based on the principle of TPP. Three-dimensional woodpile PCs consisting of in-plane rod distances ranging from 1000 nm to 2000 nm are fabricated by focusing femtosecond laser in photosensitive liquid resin ORMOCER. The properties of the PCs are also discussed, and fundamental photonic band gaps in middle-infrared range are measured, whose in-plane rod distances are 1500 nm and 2000 nm. Three-dimensional woodpile PC devices with desired defects, such as cross-waveguide and micro-laser structures, are introduced easily by TPP. We fabricate the three-dimensional woodpile PCs in the liquid resin at the fast scanning speed of 120 μm/s.

  9. Photo-excitation of carotenoids causes cytotoxicity via singlet oxygen production

    International Nuclear Information System (INIS)

    Yoshii, Hiroshi; Yoshii, Yukie; Asai, Tatsuya; Furukawa, Takako; Takaichi, Shinichi; Fujibayashi, Yasuhisa

    2012-01-01

    Highlights: ► Some photo-excited carotenoids have photosensitizing ability. ► They are able to produce ROS. ► Photo-excited fucoxanthin can produce singlet oxygen through energy transfer. -- Abstract: Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energy states below that of singlet oxygen, such as β-carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.

  10. Development of Novel Two-Photon Absorbing Chromophores

    National Research Council Canada - National Science Library

    Cooper, Thomas M; Heinrichs, James; Tan, Loon-Seng; Urbas, Augustine M; Fleitz, Paul A; Rogers, Joy E; Slagle, Jonathan E; McLean, Daniel G; Sutherland, Richard L; Brant, Mark

    2006-01-01

    There has been much interest in the development of two-photon absorbing materials and many efforts to understand the nonlinear absorption properties of these dyes, but this area is still not well understood...

  11. Standard Model Higgs decay for two Photons in CMS

    CERN Multimedia

    Daniel Denegri

    2000-01-01

    Simulated two-photon mass distribution for SM Higgs and expected background in the CMS PbW04 crystal calorimeter for an integrated luminosity of 10 . 5 pb-1, with detailed simulation of calorimeter response.

  12. Two-photon directed evolution of green fluorescent proteins.

    Science.gov (United States)

    Stoltzfus, Caleb R; Barnett, Lauren M; Drobizhev, Mikhail; Wicks, Geoffrey; Mikhaylov, Alexander; Hughes, Thomas E; Rebane, Aleksander

    2015-07-06

    Directed evolution has been used extensively to improve the properties of a variety of fluorescent proteins (FPs). Evolutionary strategies, however, have not yet been used to improve the two-photon absorption (2PA) properties of a fluorescent protein, properties that are important for two-photon imaging in living tissues, including the brain. Here we demonstrate a technique for quantitatively screening the two-photon excited fluorescence (2PEF) efficiency and 2PA cross section of tens of thousands of mutant FPs expressed in E. coli colonies. We use this procedure to move EGFP through three rounds of two-photon directed evolution leading to new variants showing up to a 50% enhancement in peak 2PA cross section and brightness within the near-IR tissue transparency wavelength range.

  13. Electromagnetically induced two-photon transparency in rubidium atoms

    International Nuclear Information System (INIS)

    Wang, D.; Gao, J.Y.; Xu, J.H.; Bassani, F.; La Rocca, G.C.; Salerno Univ.

    2001-01-01

    We present an experimental demonstration of electromagnetically induced two-photon transparency (EITT) in room temperature rubidium vapor. The 8S 1/2 to 5P 1/2 fluorescence is used to monitor the 5S 1/2 (F = 3) to 8S 1/2 (F = 3) two-photon absorption near resonance with the intermediate state 5P 3/2 . A controlling pump laser beam is employed to coherently couple the 5P 3/2 and 5D 5/2 states, thus producing two dressed intermediate states which give rise to destructive interference in the two-photon transition. An induced two-photon transparency of about 80% has been obtained at resonance; our experimental findings are in good agreement with the general theory of Agarwal et al. (1996), when the appropriate spectroscopic parameters are used. (orig.)

  14. A near-infrared genetically targetable and activatable photosensitizer

    Science.gov (United States)

    He, Jianjun; Wang, Yi; Missinato, Maria A.; Onuoha, Ezenwa; Perkins, Lydia A.; Watkins, Simon C.; St. Croix, Claudette M.; Tsang, Michael; Bruchez, Marcel P.

    2016-01-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species (ROS) that can be utilized for functional manipulation of living cells, including protein inactivation, targeted damage introduction, and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer inside the cell. By binding a heavy-atom substituted fluorogenic dye with a genetically encoded Fluorogen Activating Protein (FAP), we demonstrate an ‘on-demand’ activated photosensitizer that produces singlet oxygen and fluorescence only when FAP-bound and activated with near infrared light. This Targeted and Activated Photosensitizer (TAPs) approach enables protein inactivation and targeted cell killing in cultured cells and rapid targeted lineage ablation in living larval and adult zebrafish. The near-infrared excitation and emission of this FAP-TAPs photosensitizer module provides a new spectral range for photosensitizer proteins, useful for imaging, manipulation and cellular ablation deep within living organisms. PMID:26808669

  15. Malachite green derivatives for two-photon RNA detection.

    Science.gov (United States)

    Lux, Jacques; Peña, Eduardo José; Bolze, Frédéric; Heinlein, Manfred; Nicoud, Jean-François

    2012-05-29

    The design, preparation and characterisation of a library of malachite green (MG) derivatives for two-photon RNA labelling is described. Some of these MG derivatives exhibit an increased affinity for an MG-aptamer, as well as improved two-photon sensitivity when compared to the classical malachite green chloride. The underlying mechanisms and potential benefits for in vivo RNA visualisation are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Mass distribution for the two-photon channel

    CERN Multimedia

    ATLAS, collaboration

    2012-01-01

    Mass distribution for the two-photon channel. The strongest evidence for this new particle comes from analysis of events containing two photons. The smooth dotted line traces the measured background from known processes. The solid line traces a statistical fit to the signal plus background. The new particle appears as the excess around 126.5 GeV. The full analysis concludes that the probability of such a peak is three chances in a million.

  17. Two-photon photovoltaic effect in gallium arsenide.

    Science.gov (United States)

    Ma, Jichi; Chiles, Jeff; Sharma, Yagya D; Krishna, Sanjay; Fathpour, Sasan

    2014-09-15

    The two-photon photovoltaic effect is demonstrated in gallium arsenide at 976 and 1550 nm wavelengths. A waveguide-photodiode biased in its fourth quadrant harvests electrical power from the optical energy lost to two-photon absorption. The experimental results are in good agreement with simulations based on nonlinear wave propagation in waveguides and the drift-diffusion model of carrier transport in semiconductors. Power efficiency of up to 8% is theoretically predicted in optimized devices.

  18. Two-photon quantum interference in a Michelson interferometer

    International Nuclear Information System (INIS)

    Odate, Satoru; Wang Haibo; Kobayashi, Takayoshi

    2005-01-01

    We have observed two-photon quantum interference in a Michelson interferometer. For the first time, we experimentally demonstrated two-photon quantum interference patterns, which show the transition from nonsubwavelength interference fringes to the general subwavelength interference. At the same time, a photon bunching effect was also shown by a postselection. The |1, 1> state with a single photon in a mode corresponding to each arm of the interferometer was exclusively postselected by using path difference between two arms

  19. Functional polymers by two-photon 3D lithography

    Energy Technology Data Exchange (ETDEWEB)

    Infuehr, Robert [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, 1040 Vienna (Austria) and Institute of Applied Synthetic Chemistry, Vienna University of Technology, Karlsplatz 13, 1040 Vienna (Austria); Pucher, Niklas; Heller, Christian [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, 1040 Vienna (Austria); Institute of Applied Synthetic Chemistry, Vienna University of Technology, Karlsplatz 13, 1040 Vienna (Austria); Lichtenegger, Helga [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, 1040 Vienna (Austria); Liska, Robert [Institute of Applied Synthetic Chemistry, Vienna University of Technology, Karlsplatz 13, 1040 Vienna (Austria); Schmidt, Volker; Kuna, Ladislav; Haase, Anja [Institute of Nanostructured Materials and Photonics, Joanneum Research, Franz-Pichler-Strasse 30, 8160 Weiz (Austria); Stampfl, Juergen [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, 1040 Vienna (Austria)

    2007-12-15

    In the presented work, two-photon 3D lithography and selective single-photon photopolymerization in a prefabricated polydimethylsiloxane matrix is presented as an approach with potential applicability of waveguide writing in 3D by two-photon polymerization. Photopolymers based on acrylate chemistry were used in order to evaluate the optical capabilities of the available two-photon system. Several photoinitiators, tailored for two-photon absorption, were tested in a mixture of trimethylolpropane triacrylate and ethoxylated trimethylolpropane triacrylate. Best results were obtained with a recently synthesized diynone-based photoinitiator. Feature resolutions in the range of 300 nm were achieved. Due to the cross-conjugated nature of that donor-{pi}-acceptor-{pi}-donor system a high two-photon absorption activity was achieved. Therefore, a resin mixture containing only 0.025 wt% of photoinitiator was practical for structuring by two-photon polymerization. The required initiator content was therefore a factor of 100 lower than in traditional one-photon lithography. The aim of the second part of this work was to fabricate optical waveguides by selectively irradiating a polymer network, which was swollen by a monomer. The monomer was polymerized by conventional single-photon polymerization and the uncured monomer was removed by evaporation at elevated temperatures. This treatment leads to a local change in refractive index. Refractive index changes in the range of {delta}n = 0.01 ({delta}n/n = 0.7%) were achieved, which is sufficient for structuring waveguides for optoelectronic applications.

  20. Uniform silica nanoparticles encapsulating two-photon absorbing fluorescent dye

    International Nuclear Information System (INIS)

    Wu Weibing; Liu Chang; Wang Mingliang; Huang Wei; Zhou Shengrui; Jiang Wei; Sun Yueming; Cui Yiping; Xu Chunxinag

    2009-01-01

    We have prepared uniform silica nanoparticles (NPs) doped with a two-photon absorbing zwitterionic hemicyanine dye by reverse microemulsion method. Obvious solvatochromism on the absorption spectra of dye-doped NPs indicates that solvents can partly penetrate into the silica matrix and then affect the ground and excited state of dye molecules. For dye-doped NP suspensions, both one-photon and two-photon excited fluorescence are much stronger and recorded at shorter wavelength compared to those of free dye solutions with comparative overall dye concentration. This behavior is possibly attributed to the restricted twisted intramolecular charge transfer (TICT), which reduces fluorescence quenching when dye molecules are trapped in the silica matrix. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells with low cytotoxicity. - Graphical abstract: Water-soluble silica NPs doped with a two-photon absorbing zwitterionic hemicyanine dye were prepared. They were found of enhanced one-photon and two-photon excited fluorescence compared to free dye solutions. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells.

  1. Virucidal Nanofiber Textiles Based on Photosensitized Production of Singlet Oxygen

    Czech Academy of Sciences Publication Activity Database

    Lhotáková, Y.; Plištil, L.; Morávková, A.; Kubát, Pavel; Lang, Kamil; Forstová, J.; Mosinger, J.

    2012-01-01

    Roč. 7, č. 11 (2012), e49226 E-ISSN 1932-6203 R&D Projects: GA ČR GAP208/10/1678 Institutional support: RVO:61388955 ; RVO:61388980 Keywords : photosynthesis * biomaterials * nanofiber textiles Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.730, year: 2012

  2. Two-photon flow cytometer with laser scanning Bessel beams

    Science.gov (United States)

    Wang, Yongdong; Ding, Yu; Ray, Supriyo; Paez, Aurelio; Xiao, Chuan; Li, Chunqiang

    2016-03-01

    Flow cytometry is an important technique in biomedical discovery for cell counting, cell sorting and biomarker detection. In vivo flow cytometers, based on one-photon or two-photon excited fluorescence, have been developed for more than a decade. One drawback of laser beam scanning two-photon flow cytometer is that the two-photon excitation volume is fairly small due to the short Rayleigh range of a focused Gaussian beam. Hence, the sampling volume is much smaller than one-photon flow cytometry, which makes it challenging to count or detect rare circulating cells in vivo. Bessel beams have narrow intensity profiles with an effective spot size (FWHM) as small as several wavelengths, making them comparable to Gaussian beams. More significantly, the theoretical depth of field (propagation distance without diffraction) can be infinite, making it an ideal solution as a light source for scanning beam flow cytometry. The trade-off of using Bessel beams rather than a Gaussian beam is the fact that Bessel beams have small concentric side rings that contribute to background noise. Two-photon excitation can reduce this noise, as the excitation efficiency is proportional to intensity squared. Therefore, we developed a two-photon flow cytometer using scanned Bessel beams to form a light sheet that intersects the micro fluidic channel.

  3. Exposure of vitamins to UVB and UVA radiation generates singlet oxygen.

    Science.gov (United States)

    Knak, Alena; Regensburger, Johannes; Maisch, Tim; Bäumler, Wolfgang

    2014-05-01

    Deleterious effects of UV radiation in tissue are usually attributed to different mechanisms. Absorption of UVB radiation in cell constituents like DNA causes photochemical reactions. Absorption of UVA radiation in endogenous photosensitizers like vitamins generates singlet oxygen via photosensitized reactions. We investigated two further mechanisms that might be involved in UV mediated cell tissue damage. Firstly, UVB radiation and vitamins also generate singlet oxygen. Secondly, UVB radiation may change the chemical structure of vitamins that may change the role of such endogenous photosensitizers in UVA mediated mechanisms. Vitamins were irradiated in solution using monochromatic UVB (308 nm) or UVA (330, 355, or 370 nm) radiation. Singlet oxygen was directly detected and quantified by its luminescence at 1270 nm. All investigated molecules generated singlet oxygen with a quantum yield ranging from 0.007 (vitamin D3) to 0.64 (nicotinamide) independent of the excitation wavelength. Moreover, pre-irradiation of vitamins with UVB changed their absorption in the UVB and UVA spectral range. Subsequently, molecules such as vitamin E and vitamin K1, which normally exhibit no singlet oxygen generation in the UVA, now produce singlet oxygen when exposed to UVA at 355 nm. This interplay of different UV sources is inevitable when applying serial or parallel irradiation with UVA and UVB in experiments in vitro. These results should be of particular importance for parallel irradiation with UVA and UVB in vivo, e.g. when exposing the skin to solar radiation.

  4. Interference and complementarity for two-photon hybrid entangled states

    International Nuclear Information System (INIS)

    Nogueira, W. A. T.; Santibanez, M.; Delgado, A.; Saavedra, C.; Neves, L.; Lima, G.; Padua, S.

    2010-01-01

    In this work we generate two-photon hybrid entangled states (HESs), where the polarization of one photon is entangled with the transverse spatial degree of freedom of the second photon. The photon pair is created by parametric down-conversion in a polarization-entangled state. A birefringent double-slit couples the polarization and spatial degrees of freedom of these photons, and finally, suitable spatial and polarization projections generate the HES. We investigate some interesting aspects of the two-photon hybrid interference and present this study in the context of the complementarity relation that exists between the visibility of the one-photon and that of the two-photon interference patterns.

  5. Cell assay using a two-photon-excited europium chelate.

    Science.gov (United States)

    Xiao, Xudong; Haushalter, Jeanne P; Kotz, Kenneth T; Faris, Gregory W

    2011-08-01

    We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu(3+) emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles.

  6. Investigation of the two-photon polymerisation of a Zr-based inorganic-organic hybrid material system

    International Nuclear Information System (INIS)

    Bhuian, B.; Winfield, R.J.; O'Brien, S.; Crean, G.M.

    2006-01-01

    Two-photon polymerisation of photo-sensitive materials allows the fabrication of three dimensional micro- and nano-structures for photonic, electronic and micro-system applications. However the usable process window and the applicability of this fabrication technique is significantly determined by the properties of the photo-sensitive material employed. In this study investigation of a custom inorganic-organic hybrid system, cross-linked by a two-photon induced process, is described. The material was produced by sol-gel synthesis using a silicon alkoxide species that also possessed methacrylate functionality. Stabilized zirconium alkoxide precursors were added to the precursor solution in order to reduce drying times and impart enhanced mechanical stability to deposited films. This enabled dry films to be used in the polymerisation process. A structural, optical and mechanical analysis of the optimised sol-gel material is presented. A Ti:sapphire laser with 80 MHz repetition rate, 100 fs pulse duration and 795 nm is used. The influence of both material system and laser processing parameters including: laser power, photo-initiator concentration and zirconium loading, on achievable micro-structure and size is presented

  7. Quantitative photoacoustic imaging of two-photon absorption

    Science.gov (United States)

    Bardsley, Patrick; Ren, Kui; Zhang, Rongting

    2018-01-01

    Photoacoustic tomography (PAT) is a hybrid imaging modality where we intend to reconstruct optical properties of heterogeneous media from measured ultrasound signals generated by the photoacoustic effect. In recent years, there have been considerable interests in using PAT to image two-photon absorption, in addition to the usual single-photon absorption, inside diffusive media. We present a mathematical model for quantitative image reconstruction in two-photon photoacoustic tomography (TP-PAT). We propose a computational strategy for the reconstruction of the optical absorption coefficients and provide some numerical evidences based on synthetic photoacoustic acoustic data to demonstrate the feasibility of quantitative reconstructions in TP-PAT.

  8. Direct Writing of Photonic Structures by Two-Photon Polymerization

    Directory of Open Access Journals (Sweden)

    Li Yan

    2013-11-01

    Full Text Available Single-mode dielectric-loaded surface plasmon-polariton nanowaveguides with strong mode confinement at excitation wavelength of 830 nm and high-Q polymer whispering gallery mode microcavities with surface roughness less than 12 nm have been directly written by two-photon polymerization, which pave the way to fabricate 3D plasmonic photonic structures by direct laser writing.

  9. Precision two-photon spectroscopy of alkali elements

    Indian Academy of Sciences (India)

    (HFS), isotope shifts, Stark shifts, Zeeman splittings and Lamb shifts for different atoms and molecules. The two-photon 1s→ 2s transition in hydrogen has attained fundamental importance due to its natural width of ∼1 Hz, making it suitable for use in atomic clocks. Pramana – J. Phys., Vol. 83, No. 2, August 2014. 189 ...

  10. Space-time description of the two-photon decay

    International Nuclear Information System (INIS)

    Hrasko, P.

    1981-09-01

    The time correlation of photons in a two-photon decay is shown to depend on the instantaneous nature of the wave-function collapse in an essential way so the latter hypothesis can be verified by the experimental study of these correlations. (author)

  11. Two-photon absorption and two-photon circular dichroism of hexahelicene derivatives: a study of the effect of the nature of intramolecular charge transfer

    Czech Academy of Sciences Publication Activity Database

    Díaz, C.; Vesga, Y.; Echevarria, L.; Stará, Irena G.; Starý, Ivo; Anger, E.; Shen, C.; Moussa, M. E. S.; Vanthuyne, N.; Crassous, J.; Rizzo, A.; Hernández, F. E.

    2015-01-01

    Roč. 5, č. 23 (2015), s. 17429-17437 ISSN 2046-2069 Institutional support: RVO:61388963 Keywords : [6]helicene * two photon absorption * two photon CD Subject RIV: CC - Organic Chemistry Impact factor: 3.289, year: 2015

  12. A self-assessed photosensitizer: inducing and dual-modal phosphorescence imaging of mitochondria oxidative stress.

    Science.gov (United States)

    Jing, Yang; Cao, Qian; Hao, Liang; Yang, Gang-Gang; Hu, Wei-Liang; Ji, Liang-Nian; Mao, Zong-Wan

    2018-01-02

    Two novel Ir(iii)-nitroxide conjugates have been synthesized as mitochondria-targeted multi-functional theranostic photosensitizers, capable of simultaneously inducing and dual-modal phosphorescence imaging of mitochondrial oxidative stress under two-photon excitation, thus realizing the photodynamic therapy of cancer and self-assessment of their PDT efficacies.

  13. Voltage-sensitive styryl dyes as singlet oxygen targets on the surface of bilayer lipid membrane.

    Science.gov (United States)

    Sokolov, V S; Gavrilchik, A N; Kulagina, A O; Meshkov, I N; Pohl, P; Gorbunova, Yu G

    2016-08-01

    Photosensitizers are widely used as photodynamic therapeutic agents killing cancer cells by photooxidation of their components. Development of new effective photosensitive molecules requires profound knowledge of possible targets for reactive oxygen species, especially for its singlet form. Here we studied photooxidation of voltage-sensitive styryl dyes (di-4-ANEPPS, di-8-ANEPPS, RH-421 and RH-237) by singlet oxygen on the surface of bilayer lipid membranes commonly used as cell membrane models. Oxidation was induced by irradiation of a photosensitizer (aluminum phthalocyanine tetrasulfonate) and monitored by the change of dipole potential on the surface of the membrane. We studied the drop of the dipole potential both in the case when the dye molecules were adsorbed on the same side of the lipid bilayer as the photosensitizer (cis-configuration) and in the case when they were adsorbed on the opposite side (trans-configuration). Based on a simple model, we determined the rate of oxidation of the dyes from the kinetics of change of the potential during and after irradiation. This rate is proportional to steady-state concentration of singlet oxygen in the membrane under irradiation. Comparison of the oxidation rates of various dyes reveals that compounds of ANEPPS series are more sensitive to singlet oxygen than RH type dyes, indicating that naphthalene group is primarily responsible for their oxidation. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Improvement of nanofabrication using two photon absorption by autofocus

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Byung Je; Yi, Shin Wook; Kong, Hong Jin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lim, Tae Woo; Son, Yong; Yang, Dong Yol [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2008-11-15

    Nano stereolithography using two photon absorption(TRA)by femtosecond laser is a very useful technique to fabricate 2 D and 3 D polymer micro/nano structures. Therefore many researches on the improvement of the two photon absorbed photopolymerization had been studied. Our research was focused on the position of a focused laser beam spot on the glass substrate. It is difficult to focus the laser beam on the surface of a glass substrate correctly because of the inhomogeneity of glass substrate and the glass bending due to the short distance between a glass substrate and a high numerical aperture objective lens. As a result, the fabricated structures could have the shorter aspect ratio than desired one or be washed out by a solvent of the resin. We calculated the energy and dispersion of laser beam spot focused on a glass substrate. Using these data we searched the correct focusing position and improved the nanofabrication.

  15. Two-photon polarization Fourier spectroscopy of metastable atomic hydrogen

    International Nuclear Information System (INIS)

    Duncan, A.J.; Beyer, H.-J.; Kleinpoppen, H.; Sheikh, Z.A,; B-Z Univ., Multan

    1997-01-01

    A novel Fourier-transform spectroscopic method using two-photon polarization to determine the spectral distribution of the two photons emitted in the spontaneous decay of metastable atomic hydrogen is described. The method uses birefringent retardation plates and takes advantage of the subtle interplay between the spectral properties and the entangled polarization properties of the radiation emitted in the decay. Assuming the validity of the theoretical spectral distribution, it is shown that the experimental results agree well with theory. On the other hand, success in solving the inverse problem of determining the spectral distribution from the experimental results is limited by the small number of experimental points. However, making reasonable assumptions it is deduced that the observed spectrum is characterized by a broadband signal of width (0.43 ± 0.06) x 10 16 rad s -1 and centre angular frequency (0.77 ± 0.03) x 10 16 rad s -1 in good agreement with the predictions of 0.489 x 10 16 rad s -1 and 0.775 x 10 16 rad s -1 , respectively, obtained from the theoretical spectral distribution modified to take account of the absorption of the two-photon radiation in air. The values of 1.5 fs for the coherence time and 440 nm for the coherence length for single photons of the two-photon pair which are obtained from the measured bandwidth imply that, in the ideal case, these values are determined by the essentially zero lifetime of the virtual intermediate state of the decay process rather than the long lifetime of the metastable state which, it is suggested, determines the coherence time and coherence length appropriate to certain types of fourth-order interference experiments. (Author)

  16. Image-based adaptive optics for two-photon microscopy

    OpenAIRE

    Débarre, Delphine; Botcherby, Edward J.; Watanabe, Tomoko; Srinivas, Shankar; Booth, Martin J.; Wilson, Tony

    2009-01-01

    We demonstrate wavefront sensorless aberration correction in a two-photon excited fluorescence microscope. Using analysis of the image-formation process, we have developed an optimized correction scheme permitting image-quality improvement with minimal additional exposure of the sample. We show that, as a result, our correction process induces little photobleaching and significantly improves the quality of images of biological samples. In particular, increased visibility of small structures i...

  17. Two-photon exchange in pp(-) → l+ l- X

    International Nuclear Information System (INIS)

    Schrempp, B.; Schrempp, F.

    1981-01-01

    A thorough study of lepton-pair production from two-photon annihilation in pp (panti p) collisions is presented. The differential cross section is calculated over a large range of energies (27 + e - X cross section already at ISR energies, whereas at ISABELLE energies it dramatically dominates in the interval 0 + e - X data. For the ISABELLE energy range the expected O (αsub(s)) QCD contribution to pp → lambda + lambda - X, corrected for soft gluon radiation to all orders (in leading bilogarithmic approximation), was taken as a reference. At larger Qsub(T) and ISR energies the γγ contribution is negligible, whereas at √s = 800 GeV γγ/QCD approx. equal to 10-20% almost everywhere. Furthermore, two-photon candidate events from the ISR are shown to be in reasonable agreement with theory. A decomposition of the γγ cross section into contribution from both proton vertices being elastic, inelastic and of mixed configuration is given. The results provide important clues for a future isolation of the two-photon mechanism. (orig.)

  18. Two-photon coherent spectroscopy of ultracold Li atoms

    Science.gov (United States)

    Bobrov, A. A.; Vilshanskaya, E. V.; Zelener, B. B.; Saakyan, S. A.; Sautenkov, V. A.

    2018-01-01

    Our work is devoted to theoretical study of the two-photon coherent spectroscopy of 7Li atoms continuously cooled in a magneto-optical trap (MOT) on the 2S–2P transition. The ultracold atoms are transferred to highly excited Rydberg states in a two-step coherent excitation process by red and UV lasers. The red laser is detuned by -600 MHz from 2S–2P transition frequency and UV laser frequency detuning is scanned in the vicinity of +600 MHz from 2P-nS(D) transition where n∼40-100 is principal quantum number. The fluorescence signal on the 2P–2S cooling transition makes it possible to obtain a two-photon absorption spectrum. Atom-field interaction is considered in the simple three-level approximation involving a density matrix formalism. It is shown that the effect of the MOT beams on the shape of the two-photon absorption line can be taken into account by an appropriate change in the 2S–nS(D) coherence decay rate.

  19. Two-Photon Absorption in Organometallic Bromide Perovskites

    KAUST Repository

    Walters, Grant

    2015-07-21

    Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

  20. Riboflavin photosensitized oxidation of myoglobin.

    Science.gov (United States)

    Grippa, Juliana M; de Zawadzki, Andressa; Grossi, Alberto B; Skibsted, Leif H; Cardoso, Daniel R

    2014-02-05

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O₂, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation of MbFe(II)O₂ by ³Rib is (3.0 ± 0.5) × 10⁹ L·mol⁻¹·s⁻¹ and (3.1 ± 0.4) × 10⁹ L·mol⁻¹·s⁻¹ for MbFe(III) in phosphate buffer of pH 7.4 at 25 °C as determined by laser flash photolysis. The high rates are rationalized by ground state hydrophobic interactions as detected as static quenching of fluorescence from singlet-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K(a) = (1.2 ± 0.2) × 10⁴ mol·L⁻¹ with ΔH° = -112 ± 22 kJ·mol⁻¹ and ΔS° = -296 ± 75 J·mol⁻¹·K⁻¹. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration.

  1. Compensation of spherical aberration influences for two-photon polymerization patterning of large 3D scaffolds

    Science.gov (United States)

    Stichel, T.; Hecht, B.; Houbertz, R.; Sextl, G.

    2015-10-01

    Two-photon polymerization using femtosecond laser pulses at a wavelength of 515 nm is used for three-dimensional patterning of photosensitive, biocompatible inorganic-organic hybrid polymers (ORMOCER®s). In order to fabricate millimeter-sized biomedical scaffold structures with interconnected pores, medium numerical aperture air objectives with long working distances are applied which allow voxel lengths of several micrometers and thus the solidification of large scaffolds in an adequate time. It is demonstrated that during processing the refraction of the focused laser beam at the air/material interface leads to strong spherical aberration which decreases the peak intensity of the focal point spread function along with shifting and severely extending the focal region in the direction of the beam propagation. These effects clearly decrease the structure integrity, homogeneity and the structure details and therefore are minimized by applying a positioning and laser power adaptation throughout the fabrication process. The results will be discussed with respect to the resulting structural homogeneity and its application as biomedical scaffold.

  2. Photo-excitation of carotenoids causes cytotoxicity via singlet oxygen production

    Energy Technology Data Exchange (ETDEWEB)

    Yoshii, Hiroshi, E-mail: yoshii@nirs.go.jp [Research Center for Radiation Emergency Medicine, National Institute of Radiological Science, Chiba 263-8555 (Japan); Faculty of Medical Sciences, University of Fukui, Eiheiji, Fukui 910-1193 (Japan); Yoshii, Yukie, E-mail: yukiey@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Science, Chiba 263-8555 (Japan); Biomedical Imaging Research Center, University of Fukui, Eiheiji, Fukui 910-1193 (Japan); Asai, Tatsuya [Biomedical Imaging Research Center, University of Fukui, Eiheiji, Fukui 910-1193 (Japan); Faculty of Engineering, University of Fukui, Fukui 910-8507 (Japan); Furukawa, Takako [Molecular Imaging Center, National Institute of Radiological Science, Chiba 263-8555 (Japan); Biomedical Imaging Research Center, University of Fukui, Eiheiji, Fukui 910-1193 (Japan); Takaichi, Shinichi [Department of Biology, Nippon Medical School, Kawasaki, Kanagawa 211-0063 (Japan); Fujibayashi, Yasuhisa [Molecular Imaging Center, National Institute of Radiological Science, Chiba 263-8555 (Japan); Biomedical Imaging Research Center, University of Fukui, Eiheiji, Fukui 910-1193 (Japan)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Some photo-excited carotenoids have photosensitizing ability. Black-Right-Pointing-Pointer They are able to produce ROS. Black-Right-Pointing-Pointer Photo-excited fucoxanthin can produce singlet oxygen through energy transfer. -- Abstract: Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energy states below that of singlet oxygen, such as {beta}-carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.

  3. Two-photon imaging and analysis of neural network dynamics

    International Nuclear Information System (INIS)

    Luetcke, Henry; Helmchen, Fritjof

    2011-01-01

    The glow of a starry night sky, the smell of a freshly brewed cup of coffee or the sound of ocean waves breaking on the beach are representations of the physical world that have been created by the dynamic interactions of thousands of neurons in our brains. How the brain mediates perceptions, creates thoughts, stores memories and initiates actions remains one of the most profound puzzles in biology, if not all of science. A key to a mechanistic understanding of how the nervous system works is the ability to measure and analyze the dynamics of neuronal networks in the living organism in the context of sensory stimulation and behavior. Dynamic brain properties have been fairly well characterized on the microscopic level of individual neurons and on the macroscopic level of whole brain areas largely with the help of various electrophysiological techniques. However, our understanding of the mesoscopic level comprising local populations of hundreds to thousands of neurons (so-called 'microcircuits') remains comparably poor. Predominantly, this has been due to the technical difficulties involved in recording from large networks of neurons with single-cell spatial resolution and near-millisecond temporal resolution in the brain of living animals. In recent years, two-photon microscopy has emerged as a technique which meets many of these requirements and thus has become the method of choice for the interrogation of local neural circuits. Here, we review the state-of-research in the field of two-photon imaging of neuronal populations, covering the topics of microscope technology, suitable fluorescent indicator dyes, staining techniques, and in particular analysis techniques for extracting relevant information from the fluorescence data. We expect that functional analysis of neural networks using two-photon imaging will help to decipher fundamental operational principles of neural microcircuits.

  4. Two-photon imaging and analysis of neural network dynamics

    Science.gov (United States)

    Lütcke, Henry; Helmchen, Fritjof

    2011-08-01

    The glow of a starry night sky, the smell of a freshly brewed cup of coffee or the sound of ocean waves breaking on the beach are representations of the physical world that have been created by the dynamic interactions of thousands of neurons in our brains. How the brain mediates perceptions, creates thoughts, stores memories and initiates actions remains one of the most profound puzzles in biology, if not all of science. A key to a mechanistic understanding of how the nervous system works is the ability to measure and analyze the dynamics of neuronal networks in the living organism in the context of sensory stimulation and behavior. Dynamic brain properties have been fairly well characterized on the microscopic level of individual neurons and on the macroscopic level of whole brain areas largely with the help of various electrophysiological techniques. However, our understanding of the mesoscopic level comprising local populations of hundreds to thousands of neurons (so-called 'microcircuits') remains comparably poor. Predominantly, this has been due to the technical difficulties involved in recording from large networks of neurons with single-cell spatial resolution and near-millisecond temporal resolution in the brain of living animals. In recent years, two-photon microscopy has emerged as a technique which meets many of these requirements and thus has become the method of choice for the interrogation of local neural circuits. Here, we review the state-of-research in the field of two-photon imaging of neuronal populations, covering the topics of microscope technology, suitable fluorescent indicator dyes, staining techniques, and in particular analysis techniques for extracting relevant information from the fluorescence data. We expect that functional analysis of neural networks using two-photon imaging will help to decipher fundamental operational principles of neural microcircuits.

  5. Two-photon imaging and analysis of neural network dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Luetcke, Henry; Helmchen, Fritjof [Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

    2011-08-15

    The glow of a starry night sky, the smell of a freshly brewed cup of coffee or the sound of ocean waves breaking on the beach are representations of the physical world that have been created by the dynamic interactions of thousands of neurons in our brains. How the brain mediates perceptions, creates thoughts, stores memories and initiates actions remains one of the most profound puzzles in biology, if not all of science. A key to a mechanistic understanding of how the nervous system works is the ability to measure and analyze the dynamics of neuronal networks in the living organism in the context of sensory stimulation and behavior. Dynamic brain properties have been fairly well characterized on the microscopic level of individual neurons and on the macroscopic level of whole brain areas largely with the help of various electrophysiological techniques. However, our understanding of the mesoscopic level comprising local populations of hundreds to thousands of neurons (so-called 'microcircuits') remains comparably poor. Predominantly, this has been due to the technical difficulties involved in recording from large networks of neurons with single-cell spatial resolution and near-millisecond temporal resolution in the brain of living animals. In recent years, two-photon microscopy has emerged as a technique which meets many of these requirements and thus has become the method of choice for the interrogation of local neural circuits. Here, we review the state-of-research in the field of two-photon imaging of neuronal populations, covering the topics of microscope technology, suitable fluorescent indicator dyes, staining techniques, and in particular analysis techniques for extracting relevant information from the fluorescence data. We expect that functional analysis of neural networks using two-photon imaging will help to decipher fundamental operational principles of neural microcircuits.

  6. New two-photon based nanoscopic modalities and optogenetics

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    The science fiction inspired shrinking of macro-scale robotic manipulation and handling down to the micro- and nanoscale regime open new doors for exploiting the forces and torques of light for micro- and nanobiologic probing, actuation and control [1-3]. A generic approach for optimizing light-matter...... interaction on these scales involves the combination of optimal light-sculpting [4] with the use of optimized shapes in micro-robotics structures [5]. Microfabrication processes such as two-photon photo-polymerization offer three-dimensional resolutions for creating custom-designed monolithic microstructures...

  7. Combined two-photon microscopy and angiographic optical coherence tomography

    Science.gov (United States)

    Kim, Bumju; Wang, Tae Jun; Li, Qingyun; Nam, Jutaek; Hwang, Sekyu; Chung, Euiheon; Kim, Sungjee; Kim, Ki Hean

    2013-08-01

    A combined two-photon microscopy (TPM) and angiographic optical coherence tomography (OCT) is developed, which can provide molecular, cellular, structural, and vascular information of tissue specimens in vivo. This combined system is implemented by adding an OCT vasculature visualization method to the previous combined TPM and OCT, and then is applied to in vivo tissue imaging. Two animal models, a mouse brain cranial window model and a mouse ear cancer model, are used. Both molecular, cellular information at local regions of tissues, and structural, vascular information at relatively larger regions are visualized in the same sections. In vivo tissue microenvironments are better elucidated by the combined TPM and angiographic OCT.

  8. Inclusive $D*^{+-}$ Production in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

    2002-01-01

    Inclusive D^{*+-} production in two-photon collisions is studied with the L3 detector at LEP, using 683 pb^{-1} of data collected at centre-of-mass energies from 183 to 208 GeV. Differential cross sections are determined as functions of the transverse momentum and pseudorapidity of the D^{*+-} mesons in the kinematic region 1 GeV e^+e^-D^{*+-}X)$ in this kinematical region is measured and the sigma(e^+e^- ---> e^+e^- cc{bar}X) cross section is derived. The measurements are compared with next-to-leading order perturbative QCD calculations.

  9. Pulse front adaptive optics in two-photon microscopy.

    Science.gov (United States)

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-11-01

    Adaptive optics has been extensively studied for the correction of phase front aberrations in optical systems. In systems using ultrafast lasers, distortions can also exist in the pulse front (contour of constant intensity in space and time), but until now their correction has been mostly unexplored due to technological limitations. In this Letter, we apply newly developed pulse front adaptive optics, for the first time to our knowledge, to practical compensation of a two-photon fluorescence microscope. With adaptive correction of the system-induced pulse front distortion, improvements beyond conventional phase correction are demonstrated.

  10. Image-based adaptive optics for two-photon microscopy.

    Science.gov (United States)

    Débarre, Delphine; Botcherby, Edward J; Watanabe, Tomoko; Srinivas, Shankar; Booth, Martin J; Wilson, Tony

    2009-08-15

    We demonstrate wavefront sensorless aberration correction in a two-photon excited fluorescence microscope. Using analysis of the image-formation process, we have developed an optimized correction scheme permitting image-quality improvement with minimal additional exposure of the sample. We show that, as a result, our correction process induces little photobleaching and significantly improves the quality of images of biological samples. In particular, increased visibility of small structures is demonstrated. Finally, we illustrate the use of this technique on various fresh and fixed biological tissues.

  11. Imaging Live Drosophila Brain with Two-Photon Fluorescence Microscopy

    Science.gov (United States)

    Ahmed, Syeed Ehsan

    Two-photon fluorescence microscopy is an imaging technique which delivers distinct benefits for in vivo cellular and molecular imaging. Cyclic adenosine monophosphate (cAMP), a second messenger molecule, is responsible for triggering many physiological changes in neural system. However, the mechanism by which this molecule regulates responses in neuron cells is not yet clearly understood. When cAMP binds to a target protein, it changes the structure of that protein. Therefore, studying this molecular structure change with fluorescence resonance energy transfer (FRET) imaging can shed light on the cAMP functioning mechanism. FRET is a non-radiative dipole-dipole coupling which is sensitive to small distance change in nanometer scale. In this study we have investigated the effect of dopamine in cAMP dynamics in vivo. In our study two-photon fluorescence microscope was used for imaging mushroom bodies inside live Drosophila melanogaster brain and we developed a method for studying the change in cyclic AMP level.

  12. Temperature dependence of the two photon absorption in indium arsenide

    International Nuclear Information System (INIS)

    Berryman, K.W.; Rella, C.W.

    1995-01-01

    Nonlinear optical processes in semiconductors have long been a source of interesting physics. Two photon absorption (TPA) is one such process, in which two photons provide the energy for the creation of an electron-hole pair. Researchers at other FEL centers have studied room temperature TPA in InSb, InAs, and HgCdTe. Working at the Stanford Picosecond FEL Center, we have extended and refined this work by measuring the temperature dependence of the TPA coefficient in InAs over the range from 80 to 350 K at four wavelengths: 4.5, 5.06, 6.01, and 6.3 microns. The measurements validate the functional dependence of recent band structure calculations with enough precision to discriminate parabolic from non-parabolic models, and to begin to observe smaller effects, such as contributions due to the split-off band. These experiments therefore serve as a strong independent test of the Kane band theory, as well as providing a starting point for detailed observations of other nonlinear absorption mechanisms

  13. Inclusive D*(+/-) production in two photon collisions at LEP

    CERN Document Server

    Prokofiev, Denis Olegovich

    2001-01-01

    In this thesis I present my results on the measurement of the open charm production in two-photon collision events done with the L3 detector at Large Electron Positron machine (LEP). The data sample was collected from 1997 through 2000 at center-of-mass energies ranging from 183 GeV to 209 GeV, corresponding to a total integrated luminosity of 683.4pb −1. The open charm production in two-photon collision events extrapolated to the full phase space is estimated to be: s&parl0;e+e-&rarrr;e +e-cc&d1;X&parr0;=9 23±69±109±222pb. The differential cross sections d s /dpT(D*±) and d s /d:η(D*±): are also measured as functions of transverse momentum pT(D*±) and the absolute value of pseudorapidity :η(D*±):, respectively. A fit to the data estimating the relative contributions of Direct and Resolved open charm production mechanisms is performed, giving (28.7 ± 5.6)% and (71.3 ± 8.8)%, respectively. Using those relative fractions, the Direct and Resolved process cross sections yield: s&p...

  14. Sensing coherent phonons with two-photon interference

    Science.gov (United States)

    Ding, Ding; Yin, Xiaobo; Li, Baowen

    2018-02-01

    Detecting coherent phonons pose different challenges compared to coherent photons due to the much stronger interaction between phonons and matter. This is especially true for high frequency heat carrying phonons, which are intrinsic lattice vibrations experiencing many decoherence events with the environment, and are thus generally assumed to be incoherent. Two photon interference techniques, especially coherent population trapping (CPT) and electromagnetically induced transparency (EIT), have led to extremely sensitive detection, spectroscopy and metrology. Here, we propose the use of two photon interference in a three-level system to sense coherent phonons. Unlike prior works which have treated phonon coupling as damping, we account for coherent phonon coupling using a full quantum-mechanical treatment. We observe strong asymmetry in absorption spectrum in CPT and negative dispersion in EIT susceptibility in the presence of coherent phonon coupling which cannot be accounted for if only pure phonon damping is considered. Our proposal has application in sensing heat carrying coherent phonons effects and understanding coherent bosonic multi-pathway interference effects in three coupled oscillator systems.

  15. Lethal photosensitization of biofilm-grown bacteria

    Science.gov (United States)

    Wilson, Michael

    1997-12-01

    Antibacterial agents are increasingly being used for the prophylaxis and treatment of oral diseases. As these agents can be rendered ineffective by resistance development in the target organisms there is a need to develop alternative antimicrobial approaches. Light-activated antimicrobial agents release singlet oxygen and free radicals which can kill adjacent bacteria and a wide range of cariogenic and periodontopathogenic bacteria has been shown to be susceptible to such agents. In the oral cavity these organisms are present as biofilms (dental plaques) which are less susceptible to traditional antimicrobial agents than bacterial suspensions. The results of these studies have shown that biofilm-grown oral bacteria are also susceptible to lethal photosensitization although the light energy doses required are grater than those needed to kill the organisms when they are grown as aqueous suspensions.

  16. Singlet Ground State Magnetism:

    DEFF Research Database (Denmark)

    Loidl, A.; Knorr, K.; Kjems, Jørgen

    1979-01-01

    The magneticGamma 1 –Gamma 4 exciton of the singlet ground state system TbP has been studied by inelastic neutron scattering above the antiferromagnetic ordering temperature. Considerable dispersion and a pronounced splitting was found in the [100] and [110] directions. Both the band width...... and the splitting increased rapidly as the transition temperature was approached in accordance with the predictions of the RPA-theory. The dispersion is analysed in terms of a phenomenological model using interactions up to the fourth nearest neighbour....

  17. Development of a two photon microscope for tracking Drosophila larvae

    Science.gov (United States)

    Karagyozov, Doycho; Mihovilovic Skanata, Mirna; Gershow, Marc

    Current in vivo methods for measuring neural activity in Drosophila larva require immobilization of the animal. Although we can record neural signals while stimulating the sensory organs, we cannot read the behavioral output because we have prevented the animal from moving. Many research questions cannot be answered without observation of neural activity in behaving (freely-moving) animals. We incorporated a Tunable Acoustic Gradient (TAG) lens into a two-photon microscope to achieve a 70kHz axial scan rate, enabling volumetric imaging at tens of hertz. We then implemented a tracking algorithm based on a Kalman filter to maintain the neurons of interest in the field of view and in focus during the rapid three dimensional motion of a free larva. Preliminary results show successful tracking of a neuron moving at speeds reaching 500 μm/s. NIH Grant 1DP2EB022359 and NSF Grant PHY-1455015.

  18. Whole brain imaging with Serial Two-Photon Tomography

    Directory of Open Access Journals (Sweden)

    Stephen P Amato

    2016-03-01

    Full Text Available Imaging entire mouse brains at submicron resolution has historically been a challenging undertaking and largely confined to the province of dedicated atlasing initiatives. The has limited systematic investigations into important areas of neuroscience, such as neural circuits, brain mapping and neurodegeneration. In this paper, we describe in detail Serial Two-Photon (STP tomography, a robust, reliable method for imaging entire brains with histological detail. We provide examples of how the basic methodology can be extended to other imaging modalities, such as optical coherence tomography, in order to provide unique contrast mechanisms. Furthermore we provide a survey of the research that STP tomography has enabled in the field of neuroscience, provide examples of how this technology enables quantitative whole brain studies, and discuss the current limitations of STP tomography-based approaches

  19. Self-grown fiber fabrication by two-photon photopolymerization

    Science.gov (United States)

    Hidai, Hirofumi; Hwang, David J.; Grigoropoulos, Costas P.

    2008-11-01

    We demonstrate a new fiber growth mechanism in a photocurable resin by ultrafast laser illumination. A high-repetition rate (˜1 MHz) ultrafast laser beam at the wavelength of ˜523 nm was focused into an ultraviolet photocurable resin to trigger two-photon photopolymerization process. Time-resolved shadowgraphs and scattered light imaging revealed that the curing commenced in the neighborhood of the geometric focal point of the laser beam and that the fiber growth progressed mostly towards the laser source. The cured fiber was thinner and longer than the profile of the focused laser beam, facilitated by nonlinear propagation and absorption of the ultra-fast laser beam. The achieved aspect ratio of the fiber was higher than 180 with ˜10 μm mean diameter, and the average growth rate was up to ˜2 mm/s.

  20. Two-photon polymerization of immune cell scaffolds

    DEFF Research Database (Denmark)

    Olsen, Mark Holm

    and easy to use chip integrated migration platform. Free-form constructs with three-dimensional (3D) microporosity were fabricated by two-photon polymerization inside the closed microchannel of an injection molded commercially available polymer chip for analysis of directed cell migration. Acrylate...... constructs were produced as woodpile topologies with a range of pore sizes from 5x5 μm to 15x15 μm and prefilled with fibrillar collagen. Dendritic cells seeded into the polymer chip in a concentration gradient of the chemoattractant CCL21 efficiently negotiated the microporous maze structure for pore sizes...... initial in-chip fabrication of soft 3D constructs holding more than 80 % water....

  1. High-dynamic-range cationic two-photon photopolymerization

    Science.gov (United States)

    Boiko, Yuri B.; Costa, Joannes M.; Wang, Mark M.; Esener, Sadik C.

    2001-06-01

    Cationic-induced two-photon photopolymerization is demonstrated at 710 nm, using an isopropylthioxanthone/diarylidonium salt initiating system for the cationic polymerization of an epoxide. The polymerization threshold J2th is found to be approximately 1 GW/cm2, with a dynamic range of > 100, i.e. the material can be fully polymerized at intensities > 100 times the threshold level without damage. The polymerization rate R is found to be proportional to the m equals 1.7 power of the intensity, or R equals [C (J-J2th)]m equals [C (J-J2th)]1.7, which implies a significantly stronger localization of the photochemical response than that of free radical photoinitiators. R and J2th significantly improve when the concentration z of the initiator (onium salt) increases.

  2. N-dimensional integrability from two-photon coalgebra symmetry

    International Nuclear Information System (INIS)

    Ballesteros, Angel; Blasco, Alfonso; Herranz, Francisco J

    2009-01-01

    A wide class of Hamiltonian systems with N degrees of freedom and endowed with, at least, (N - 2) functionally independent integrals of motion in involution is constructed by making use of the two-photon Lie-Poisson coalgebra (h 6 , Δ). The set of (N - 2) constants of the motion is shown to be a universal one for all these Hamiltonians, irrespective of the dependence of the latter on several arbitrary functions and N free parameters. Within this large class of quasi-integrable N-dimensional Hamiltonians, new families of completely integrable systems are identified by finding explicitly a new independent integral I through the analysis of the sub-coalgebra structure of h 6 . In particular, new completely integrable N-dimensional Hamiltonians describing natural systems, geodesic flows and static electromagnetic Hamiltonians are presented

  3. Two-Photon Infrared Resonance Can Enhance Coherent Raman Scattering

    Science.gov (United States)

    Traverso, Andrew J.; Hokr, Brett; Yi, Zhenhuan; Yuan, Luqi; Yamaguchi, Shoichi; Scully, Marlan O.; Yakovlev, Vladislav V.

    2018-02-01

    In this Letter we present a new technique for attaining efficient low-background coherent Raman scattering where the Raman coherence is mediated by a tunable infrared laser in two-photon resonance with a chosen vibrational transition. In addition to the traditional benefits of conventional coherent Raman schemes, this approach offers a number of advantages including potentially higher emission intensity, reduction of nonresonant four-wave mixing background, preferential excitation of the anti-Stokes field, and simplified phase matching conditions. In particular, this is demonstrated in gaseous methane along the ν1 (A1) and ν3 (T2) vibrational levels using an infrared field tuned between 1400 and 1600 cm-1 and a 532-nm pump field. This approach has broad applications, from coherent light generation to spectroscopic remote sensing and chemically specific imaging in microscopy.

  4. Clinical multiphoton tomography and clinical two-photon microendoscopy

    Science.gov (United States)

    König, Karsten; Bückle, Rainer; Weinigel, Martin; Elsner, Peter; Kaatz, Martin

    2009-02-01

    We report on applications of high-resolution clinical multiphoton tomography based on the femtosecond laser system DermaInspectTM with its flexible mirror arm in Australia, Asia, and Europe. Applications include early detection of melanoma, in situ tracing of pharmacological and cosmetical compounds including ZnO nanoparticles in the epidermis and upper dermis, the determination of the skin aging index SAAID as well as the study of the effects of anti-aging products. In addition, first clinical studies with novel rigid high-NA two-photon 1.6 mm GRIN microendoscopes have been conducted to study the effect of wound healing in chronic wounds (ulcus ulcera) as well as to perform intrabody imaging with subcellular resolution in small animals.

  5. Fluorescent Pluronic nanodots for in vivo two-photon imaging

    International Nuclear Information System (INIS)

    Maurin, Mathieu; Vurth, Laeticia; Vial, Jean-Claude; Baldeck, Patrice; Stephan, Olivier; Marder, Seth R; Sanden, Boudewijn Van der

    2009-01-01

    We report the synthesis of new nanosized fluorescent probes based on bio-compatible polyethylene-polypropylene glycol (Pluronic) materials. In aqueous solution, mini-emulsification of Pluronic with a high fluorescent di-stryl benzene-modified derivative, exhibiting a two-photon absorption cross section as high as 2500 Goeppert-Mayer units at 800 nm, leads to nanoparticles exhibiting a hydrodynamic radius below 100 nm. We have demonstrated that these new probes with luminescence located in the spectral region of interest for bio-imaging (the yellow part of the visible spectrum) allow deep (500 μm) bio-imaging of the mice brain vasculature. The dose injected during our experiments is ten times lower when compared to the classical commercial rhodamine-B isothicyanate-Dextran system but gives similar results to homogeneous blood plasma staining. The mean fluorescent signal intensity stayed constant during more than 1 h.

  6. Primary mechanisms of photosensitization by furocoumarins

    International Nuclear Information System (INIS)

    Grossweiner, L.I.

    1981-01-01

    A proper understanding of the PUVA therapy action mechanism requires the synthesis of concepts developed at the level of molecules, single cells and whole organisms. Although progress has been made in identifying key factors within each level of organization, the interrelationships remain obscure. Important unanswered questions at the molecular and cellular levels include: (1) Which excited states of the furocoumarin in molecule (triplet or excited singlet) are involved in the formation of DNA monoadducts, and the conversion of monoadducts to cross-links. (2) How does the spectrum of the incident radiation affect the distribution of the initial photochemical products from the PUVA sensitizers. (3) What are the relative contributions of furocoumarin-DMA monoadducts, furocoumarin-DNA cross-links and singlet oxygen to mutagenesis and lethality in cells, at the furocoumarin and UV-A dose levels corresponging to PUVA therapy. Additional information about these key aspects of furocoumarin photosensitization should lead to a more definitive relationship of the cellular level events to the endpoints observed with PUVA therapy, and suggest directions for potential improvements in the current clinical procedures

  7. Singlets of fermionic gauge symmetries

    NARCIS (Netherlands)

    Bergshoeff, E.A.; Kallosh, R.E.; Rahmanov, M.A.

    1989-01-01

    We investigate under which conditions singlets of fermionic gauge symmetries which are "square roots of gravity" can exist. Their existence is non-trivial because there are no fields neutral in gravity. We tabulate several examples of singlets of global and local supersymmetry and κ-symmetry and

  8. Non-Liouvillean ion injection via resonantly enhanced two-photon ionization

    Directory of Open Access Journals (Sweden)

    B. A. Knyazev

    2004-03-01

    Full Text Available The charge-exchange method is now one of the main techniques for ion injection into accelerators and storage rings. The disadvantages of conventional methods, based on the atom or ion stripping in a material target, are emittance growth, energy straggling, and production of ions in many charge states. Recently suggested stripping methods based on direct photoionization require employment of hard-UV lasers, which still do not exist and must obviously be very bulky and expensive. An alternative method, suggested for injection of proton beams, employs excitation of the atom to 3p intermediate state with subsequent Lorentz ionization in a magnetic field gradient. This technique applies rigid requirements to laser characteristic and is not free of growing of the beam divergence. In this paper a variant of the stripping technique based on the resonantly enhanced two-photon ionization (RETPI is considered. The technique allows ionization of singly charged ions of the elements from helium to bismuth. A variant of the technique can be used for proton injection. RETPI can be applied for both ion injection and stacking, as well as for diagnostics of ion beam characteristics on the orbit. Stripping efficiency can be about 100% for the singly charged ions having the singlet ground state and decreases for the other ions. Special methods for “cleaning” unwanted atomic states in such ions, that can provide high stripping efficiency, are discussed. Excimer lasers with very moderate parameters can be employed for implementation of this technique for almost all elements. Numerical examples show that for most of the singly charged ions and for hydrogen atom necessary laser-beam energy density is merely 0.5–8  J/cm^{2} for a 1 m interaction region, and is 10 times higher for several light ions.

  9. Photosensitivity in generalized epilepsies.

    Science.gov (United States)

    Poleon, Shervonne; Szaflarski, Jerzy P

    2017-03-01

    Photosensitivity, which is the hallmark of photosensitive epilepsy (PSE), is described as an abnormal EEG response to visual stimuli known as a photoparoxysmal response (PPR). The PPR is a well-recognized phenomenon, occurring in 2-14% of patients with epilepsy but its pathophysiology is not clearly understood. PPR is electrographically described as 2-5Hz spike, spike-wave, or slow wave complexes with frontal and paracentral prevalence. Diagnosis of PPR is confirmed using intermittent photic stimulation (IPS) as well as video monitoring. The PPR can be elicited by certain types of visual stimuli including flicker, high contrast gratings, moving patterns, and rapidly modulating luminance patterns which may be encountered during e.g., watching television, playing video games, or attending discotheques. Photosensitivity may present in different idiopathic (genetic) epilepsy syndromes e.g. juvenile myoclonic epilepsy (JME) as well as non-IGE syndromes e.g. severe myoclonic epilepsy of infancy. Consequently, PPR is present in patients with diverse seizure types including absence, myoclonic, and generalized tonic-clonic (GTC) seizures. Across syndromes, abnormalities in structural connectivity, functional connectivity, cortical excitability, cortical morphology, and behavioral and neuropsychological function have been reported. Treatment of photosensitivity includes antiepileptic drug administration, and the use of non-pharmacological agents, e.g. tinted or polarizing glasses, as well as occupational measures, e.g. avoidance of certain stimuli. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Gaugino Mass without Singlets

    CERN Document Server

    Giudice, Gian Francesco; Murayama, H; Rattazzi, Riccardo; Giudice, Gian F.; Luty, Markus A.; Murayama, Hitoshi; Rattazzi, Riccardo

    1998-01-01

    In models with dynamical supersymmetry breaking in the hidden sector, the gaugino masses in the observable sector have been believed to be extremely suppressed (below 1 keV), unless there is a gauge singlet in the hidden sector with specific couplings to the observable sector gauge multiplets. We point out that there is a pure supergravity contribution to gaugino masses at the quantum level arising from the superconformal anomaly. Our results are valid to all orders in perturbation theory and are related to the `exact' beta functions for soft terms. There is also an anomaly contribution to the A terms proportional to the beta function of the corresponding Yukawa coupling. The gaugino masses are proportional to the corresponding gauge beta functions, and so do not satisfy the usual GUT relations.

  11. Two-Photon Ghost Image and Interference-Diffraction

    Science.gov (United States)

    Shih, Y. H.; Sergienko, A. V.; Pittman, T. B.; Strekalov, D. V.; Klyshko, D. N.

    1996-01-01

    One of the most surprising consequences of quantum mechanics is entanglement of two or more distance particles. The two-particle entangled state was mathematically formulated by Schrodinger. Based on this unusual quantum behavior, EPR defined their 'physical reality' and then asked the question: 'Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?' One may not appreciate EPR's criterion of physical reality and insist that 'no elementary quantum phenomenon is a phenomenon until it is a recorded phenomenon'. Optical spontaneous parametric down conversion (SPDC) is the most effective mechanism to generate an EPR type entangled two-photon state. In SPDC, an optical beam, called the pump, is incident on a birefringent crystal. The pump is intense enough so that nonlinear effects lead to the conversion of pump photons into pairs of photons, historically called signal and idler. Technically, the SPDC is said to be type-1 or type-2, depending on whether the signal and idler beams have parallel or orthogonal polarization. The SPDC conversion efficiency is typically on the order of 10(exp -9) to 10(exp -11), depending on the SPDC nonlinear material. The signal and idler intensities are extremely low, only single photon detection devices can register them. The quantum entanglement nature of SPDC has been demonstrated in EPR-Bohm experiments and Bell's inequality measurements. The following two experiments were recently performed in our laboratory, which are more closely related to the original 1935 EPR gedankenezperiment. The first experiment is a two-photon optical imaging type experiment, which has been named 'ghost image' by the physics community. The signal and idler beams of SPDC are sent in different directions, so that the detection of the signal and idler photons can be performed by two distant photon counting detectors. An aperture object (mask) is placed in front of the signal photon detector and illuminated by the signal beam through a

  12. Photosensitization and phototherapy with furocoumarins: A quantum-chemical study

    International Nuclear Information System (INIS)

    Serrano-Perez, Juan Jose; Serrano-Andres, Luis; Merchan, Manuela

    2008-01-01

    The effect of electromagnetic radiation on biological objects extends from heating to complex photochemistry, and includes DNA alteration, that properly modified in damaged cells may entail beneficial effects. In this regard, psoralen + UV-A (PUVA) therapy, in which furocoumarins, psoralen-like chromophores, are used as photosensitizers and photoreactants with DNA bases, is one of the most promising strategies against a plethora of diseases. Understanding the underlying photochemical mechanisms is crucial to design effective drugs without undesired side effects. We have undertaken a quantum-mechanical study on the photophysics and photochemistry of furocoumarins, analyzing firstly the most efficient way in which the lowest excited triplet state, as protagonist of the photosensitizing action, is populated from the initially promoted singlet states, and secondly the basics of the formation of furocoumarin-DNA photoadducts

  13. Chlorin photosensitizers sterically designed to prevent self-aggregation.

    Science.gov (United States)

    Uchoa, Adjaci F; de Oliveira, Kleber T; Baptista, Mauricio S; Bortoluzzi, Adailton J; Iamamoto, Yassuko; Serra, Osvaldo A

    2011-11-04

    The synthesis and photophysical evaluation of new chlorin derivatives are described. The Diels-Alder reaction between protoporphyrin IX dimethyl ester and substituted maleimides furnishes endo-adducts that completely prevent the self-aggregation of the chlorins. Fluorescence, resonant light scattering (RLS) and (1)H NMR experiments, as well as X-ray crystallographic have demonstrated that the configurational arrangement of the synthesized chlorins prevent π-stacking interactions between macrocycles, thus indicating that it is a nonaggregating photosensitizer with high singlet oxygen (Φ(Δ)) and fluorescence (Φ(f)) quantum yields. Our results show that this type of synthetic strategy may provide the lead to a new generation of PDT photosensitizers.

  14. Riboflavin as a photosensitizer. Effects on human health and food quality.

    Science.gov (United States)

    Cardoso, Daniel R; Libardi, Silvia H; Skibsted, Leif H

    2012-05-01

    Riboflavin, vitamin B₂, and flavins (as riboflavin building blocks or degradation products) are efficient photosensitizers inducing oxidative damage to light-exposed tissue and food by substrate-dependent mechanisms, for which protection is offered by specific nutrients. Phenolic and N-heterocyclic amino acids and their peptides and proteins deactivate triplet-excited state riboflavin in diffusion controlled processes, efficiently competing with deactivation by oxygen, resulting in direct (so called Type I) protein degradation through electron transfer or proton-coupled electron transfer. In light-exposed tissue, such often long lived protein radicals may as primary photoproducts initiate lipid and vitamin oxidation. In contrast, for lipid systems, oxygen deactivation of triplet-excited state riboflavin, resulting in formation of singlet oxygen, is under aerobic conditions faster than direct deactivation by lipids, which otherwise under anaerobic conditions occurs as hydrogen atom transfer from polyunsaturated lipids to triplet riboflavin. Singlet oxygen adds to unsaturated lipids and forms lipid hydroperoxides as primary lipid oxidation products or oxidizes proteins (Type II mechanism). Carotenoids seem not to deactivate triplet riboflavin, while chromanols like vitamin E and plant polyphenols are efficient in such deactivation yielding protection of proteins and lipids by these phenols. Indirect protection against the triplet reactivity of riboflavin is further important for polyphenols as riboflavin singlet excited state quenchers in effectively preventing riboflavin intersystem crossing to yield the reactive triplet state. Riboflavin photosensitization becomes critical for degradation of proteins, unsaturated lipids, and folate, thiamine, ascorbate and other vitamins during light exposure of food during storage. For skin, eye and other tissue exposed to high intensity light, dietary polyphenols like flavonoids are important in direct protection against

  15. Time-resolved two-photon photoemission from metal surfaces

    CERN Document Server

    Weinelt, M

    2002-01-01

    The Rydberg-like series of image-potential states is a prototype system for loosely bound electrons at a metal surface. The electronic structure and the femtosecond dynamics of these states is studied by high-resolution energy-and time-resolved two-photon photoemission spectroscopy. The electron trapped in the image potential moves virtually freely laterally to the surface where it is subject to inelastic and quasielastic scattering processes which cause decay of population and phase relaxation. The influence of surface corrugation on these processes has been investigated for adsorbates on Cu(001) and stepped Cu(117) and Cu(119) surfaces which are vicinal to Cu(001). The dynamics depend on both the distance of the electron in front of the surface and the parallel momentum. For CO molecules on Cu(001) inelastic scattering into bulk states and adsorbate-induced resonances determine the decay rate. For small numbers of Cu adatoms on Cu(001) and the vicinal surfaces the decay rate of image-potential states is sig...

  16. Cationic two-photon induced polymerization with high dynamic range

    Science.gov (United States)

    Boiko, Yuri B.; Costa, Joannes; Wang, Mark M.; Esener, Sadik C.

    2001-05-01

    Cationic-induced two-photon photo-polymerization is demonstrated at 710 nm, using an isopropylthioxanthone / diarylidonium salt initiating system for the cationic polymerization of an epoxide. In-situ monitoring of the polymer conversion using interferometry allows for determination of the polymerization threshold J2th, polymerization rate R and its dependence of initiator's concentration z. Best J2th achieved is 1 GW/cm 2 , with a dynamic range of > 100, i.e. the material can be fully polymerized at intensities > 100 times the threshold level without damage. The R is found to be proportional to the m=1.7 power of the intensity, or R =[C(J-J2th)]m =[C(J-J2th)]1.7 , which implies a significantly stronger localization of the photochemical response than that of free radical photoinitiators. Both R and J2th significantly improve when the concentration z of the initiator (onium salt) increases, reduction of J2th exhibiting z -m trend.

  17. Search for Singlet Fission Chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Havlas, Z.; Akdag, A.; Smith, M. B.; Dron, P.; Johnson, J. C.; Nozik, A. J.; Michl, J.

    2012-01-01

    Singlet fission, in which a singlet excited chromophore shares its energy with a ground-state neighbor and both end up in their triplet states, is of potential interest for solar cells. Only a handful of compounds, mostly alternant hydrocarbons, are known to perform efficiently. In view of the large number of conditions that a successful candidate for a practical cell has to meet, it appears desirable to extend the present list of high performers to additional classes of compounds. We have (i) identified design rules for new singlet fission chromophores and for their coupling to covalent dimers, (ii) synthesized them, and (iii) evaluated their performance as neat solids or covalent dimers.

  18. Photosensitive Strip RETHGEM

    CERN Document Server

    Peskov, Vladimir; Nappi, E.; Oliveira, R.; Paic, G.; Pietropaolo, F.; Picchi, P.

    2008-01-01

    An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains - close to the breakdown limit. Detectors with active areas of 10cm x10cm and 10cm x20cm were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large area detectors for UV visualization, as for example, in Cherenkov imaging devices.

  19. Distribution of quantum information between an atom and two photons

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Bernhard

    2008-11-03

    The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

  20. Dynamical modeling of pulsed two-photon interference

    Science.gov (United States)

    Fischer, Kevin A.; Müller, Kai; Lagoudakis, Konstantinos G.; Vučković, Jelena

    2016-11-01

    Single-photon sources are at the heart of quantum-optical networks, with their uniquely quantum emission and phenomenon of two-photon interference allowing for the generation and transfer of nonclassical states. Although a few analytical methods have been briefly investigated for describing pulsed single-photon sources, these methods apply only to either perfectly ideal or at least extremely idealized sources. Here, we present the first complete picture of pulsed single-photon sources by elaborating how to numerically and fully characterize non-ideal single-photon sources operating in a pulsed regime. In order to achieve this result, we make the connection between quantum Monte-Carlo simulations, experimental characterizations, and an extended form of the quantum regression theorem. We elaborate on how an ideal pulsed single-photon source is connected to its photocount distribution and its measured degree of second- and first-order optical coherence. By doing so, we provide a description of the relationship between instantaneous source correlations and the typical experimental interferometers (Hanbury-Brown and Twiss, Hong-Ou-Mandel, and Mach-Zehnder) used to characterize such sources. Then, we use these techniques to explore several prototypical quantum systems and their non-ideal behaviors. As an example numerical result, we show that for the most popular single-photon source—a resonantly excited two-level system—its error probability is directly related to its excitation pulse length. We believe that the intuition gained from these representative systems and characters can be used to interpret future results with more complicated source Hamiltonians and behaviors. Finally, we have thoroughly documented our simulation methods with contributions to the Quantum Optics Toolbox in Python in order to make our work easily accessible to other scientists and engineers.

  1. Two photon microscopy for studies of xenobiotics in human skin

    Science.gov (United States)

    Simonsson, Carl; Smedh, Maria; Jonson, Charlotte; Karlberg, Ann-Therese; Ericson, Marica B.

    2007-07-01

    For successful uptake and distribution of drugs from transdermal formulations, it is important to understand the skin barrier function. Innovative advances in modern microscopy have provided valuable tools to study the interaction between the skin and xenobiotics. Two-photon microscopy (TPM) allows non-invasive visualization of fluorescent compounds in the skin. The advantages of TPM over conventional confocal microscopy are better light penetration into highly scattering and absorbing tissue such as human skin, improved detection efficiency, limited out of focus photobleaching and reduced phototoxic effects. We present TPM as an alternative non-invasive in vitro method to study chemical penetration enhancement of fluorescent model drugs. The permeability of sulforhodamine B (SRB) through human epidermis was measured with vertical diffusion cells. The absorption was visualized using TPM after 24 h passive diffusion. We have evaluated variations in physicochemical parameters controlling dermal drug uptake induced by the penetration enhancer oleic acid according to methods previously described by Yu et al. Optical sectioning by TPM was compared with cryosectioning. Oleic acid significantly increased penetration of sulforhodamine. TPM images demonstrate a four-fold increase in the partition coefficient. In addition, a six-fold increase in the concentration gradient was found over stratum corneum. Better light penetration and detection efficiency increase maximum imaging depth in TPM compared to conventional confocal microscopy, however loss of signal due to scattering and absorption is still significant and will affect distribution profiles generated by optical sectioning. A true concentration profile cannot be established without better knowledge about signal losses in the skin.

  2. Two Photon Absorption Cross-Section Of New Fluophore Compounds

    Science.gov (United States)

    El-Nadi, Lotfia; Farag, Ahmad M.; El-Sherbiny, Ashraf; Gamal, Yosr E.

    2005-03-01

    This study is a continuation of previous work carried by our group to synthesize and develop new fluophore compounds that could be used in fluorescence light microscopy for imaging biological molecules. Marking biological cells by such fluophores allow real time observation of single molecules. We synthesized and determined the absorption and emission spectra of the following new fluophores: ( L1 ) 4-Amino-2-oxo-2H-pyrido[1,2-a]pyrimidine-3-carbothioic phenyl-amide. ( L9 ) 3-(2-benzenesulfonyl-3-dimethylamino acryloyl) coumarine. ( L11 ) 1-(4-bromophenyle)-4-(coumarin-3-carbonyl)-1H-pyrazole- 3 - carboxylic acid ethyl ester. The absorption spectra are found to peak at wavelengths 285, 358 and 370 nm. [for (L1)], 285, 320 and 360 nm. [for (L9)] and 285 and 360 nm. [for (L11)] Emission lines are observed at 486 nm., 430 nm. and 470 nm for ( L1 ), (L9) and (L11), respectively. These emission lines peaked when (L1), (L9) and (L11) were excited by 370,366 and 360 nm, respectively. This means that all three fluophores could be excited by two photon absorption (TPA) from IR laser of wavelength 730+- 10 nm. or three photon absorption (THPA) of IR laser at 1064+-20 nm. nearly without tuning. Multiphoton excitation of fluophors marking biological samples is advantageous over single photon excitation. The (TPA) and (THPA) fluorescent intensities have been measured for the three fluophors in DMF solution at different concentrations using both 90 femtosecond Ti-sapphire laser at powers up to 250 MW and 7 nanosecond Nd:YAG laser up to 10 MW. The estimated (TPA) cross-sections are of the order of 10-39 cm2 / photon and the (THPA) cross-sections are less by a factor more than 10 times that of (TPA).

  3. Distribution of quantum information between an atom and two photons

    International Nuclear Information System (INIS)

    Weber, Bernhard

    2008-01-01

    The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

  4. The rigid amphipathic fusion inhibitor dUY11 acts through photosensitization of viruses.

    Science.gov (United States)

    Vigant, Frederic; Hollmann, Axel; Lee, Jihye; Santos, Nuno C; Jung, Michael E; Lee, Benhur

    2014-02-01

    Rigid amphipathic fusion inhibitors (RAFIs) are lipophilic inverted-cone-shaped molecules thought to antagonize the membrane curvature transitions that occur during virus-cell fusion and are broad-spectrum antivirals against enveloped viruses (Broad-SAVE). Here, we show that RAFIs act like membrane-binding photosensitizers: their antiviral effect is dependent on light and the generation of singlet oxygen ((1)O(2)), similar to the mechanistic paradigm established for LJ001, a chemically unrelated class of Broad-SAVE. Photosensitization of viral membranes is a common mechanism that underlies these Broad-SAVE.

  5. Interaction of plasmalogens and their diacyl analogs with singlet oxygen in selected model systems

    Science.gov (United States)

    Broniec, Agnieszka; Klosinski, Radoslaw; Pawlak, Anna; Wrona-Krol, Marta; Thompson, David; Sarna, Tadeusz

    2011-01-01

    Plasmalogens (Plg) are phospholipids containing vinyl ether linkage at the sn-1 position of the glycerophospholipid backbone. In spite of being quite abundant in humans, the biological role of plasmalogens remains speculative. It has been postulated that plasmalogens are physiological antioxidants with the vinyl ether functionality serving as sacrificial trap for free radicals and singlet oxygen. However, no quantitative data on the efficiency of plasmalogens to scavenge these reactive species are available. In this study, rate constants of quenching of singlet oxygen, generated by photosensitized energy transfer, by several plasmalogens and, for comparison, by their diacyl analogs, were determined by time-resolved detection of phosphorescence at 1270 nm. Relative rates of the interaction of singlet oxygen, with plasmalogens and other lipids in solution and liposomal membranes were measured by electron paramagnetic resonance oximetry and product analysis, employing HPLC-EC detection of cholesterol hydroperoxides and iodometric assay of lipid hydroperoxides. Results show that singlet oxygen interacts with plasmalogens significantly faster than with the other lipids, with he corresponding rate constants being by one-two orders of magnitude greater. The quenching of singlet oxygen by plasmalogens is mostly reactive in nature and results from its preferential interaction with the vinyl ether bond. The data suggest that plasmalogens could protect unsaturated membrane lipids against oxidation induced by singlet oxygen, providing that the oxidation products are not excessively cytotoxic. PMID:21236336

  6. Two-photon absorption and spectroscopy of the lowest two-photon transition in small donor-acceptor-substituted organic molecules

    Science.gov (United States)

    Beels, Marten T.; Biaggio, Ivan; Reekie, Tristan; Chiu, Melanie; Diederich, François

    2015-04-01

    We determine the dispersion of the third-order polarizability of small donor-acceptor substituted organic molecules using wavelength-dependent degenerate four-wave mixing experiments in solutions with varying concentrations. We find that donor-acceptor-substituted molecules that are characterized by extremely efficient off-resonant nonlinearities also have a correspondingly high two-photon absorption cross section. The width and shape of the first two-photon resonance for these noncentrosymmetric molecules follows what is expected from their longest wavelength absorption peak, and the observed two-photon absorption cross sections are record high when compared to the available literature data, the size of the molecule, and the fundamental limit for two-photon absorption to the lowest excited state, which is essentially determined by the number of conjugated electrons and the excited-state energies. The two-photon absorption of the smallest molecule, which only has 16 electrons in its conjugated system, is one order of magnitude larger than for the molecule called AF-50, a reference molecule for two-photon absorption [O.-K. Kim et al., Chem. Mater. 12, 284 (2000), 10.1021/cm990662r].

  7. A Photosensitizer-Loaded DNA Origami Nanosystem for Photodynamic Therapy.

    Science.gov (United States)

    Zhuang, Xiaoxi; Ma, Xiaowei; Xue, Xiangdong; Jiang, Qiao; Song, Linlin; Dai, Luru; Zhang, Chunqiu; Jin, Shubin; Yang, Keni; Ding, Baoquan; Wang, Paul C; Liang, Xing-Jie

    2016-03-22

    Photodynamic therapy (PDT) offers an alternative for cancer treatment by using ultraviolet or visible light in the presence of a photosensitizer and molecular oxygen, which can produce highly reactive oxygen species that ultimately leading to the ablation of tumor cells by multifactorial mechanisms. However, this technique is limited by the penetration depth of incident light, the hypoxic environment of solid tumors, and the vulnerability of photobleaching reduces the efficiency of many imaging agents. In this work, we reported a cellular level dual-functional imaging and PDT nanosystem BMEPC-loaded DNA origami for photodynamic therapy with high efficiency and stable photoreactive property. The carbazole derivative BMEPC is a one- and two-photon imaging agent and photosensitizer with large two-photon absorption cross section, which can be fully excited by near-infrared light, and is also capable of destroying targets under anaerobic condition by generating reactive intermediates of Type I photodynamic reactions. However, the application of BMEPC was restricted by its poor solubility in aqueous environment and its aggregation caused quenching. We observed BMEPC-loaded DNA origami effectively reduced the photobleaching of BMEPC within cells. Upon binding to DNA origami, the intramolecular rotation of BMEPC became proper restricted, which intensify fluorescence emission and radicals production when being excited. After the BMEPC-loaded DNA origami are taken up by tumor cells, upon irradiation, BMEPC could generate free radicals and be released due to DNA photocleavage as well as the following partially degradation. Apoptosis was then induced by the generation of free radicals. This functional nanosystem provides an insight into the design of photosensitizer-loaded DNA origami for effective intracellular imaging and photodynamic therapy.

  8. Targeted oxidation of Torpedo californica acetylcholinesterase by singlet oxygen.

    Science.gov (United States)

    Weiner, Lev; Roth, Esther; Silman, Israel

    2011-01-01

    The photosensitizer, methylene blue (MB), is a strong reversible inhibitor of Torpedo californica acetylcholinesterase (AChE) in the dark. Under illumination it causes irreversible inactivation. Loss of fluorescence of the singlet oxygen ((1)O(2)) trap, 9,10-dimethylanthracene, was retarded in the presence of AChE, and the rate of photo-inactivation was increased in the presence of D(2)O, indicating that inactivation was due to (1)O(2) generated by the photosensitizer. CD revealed slightly reduced far-UV ellipticity, and slightly enhanced binding of an amphiphilic probe, indicating limited unfolding of the photo-oxidized AChE. However, both near-UV ellipticity and intrinsic fluorescence were markedly reduced, suggesting photo-oxidative damage to tryptophans, (Trp) supported by appearance of novel emission peaks ascribed to N'-formylkynurenine and/or kynurenine. Like other partially unfolded forms, the photo-oxidized AChE was sensitive to proteolysis. Photosensitized inactivation produced exclusively chemically cross-linked dimers, whereas irradiation of a partially unfolded state generated higher-order oligomers. The active-site gorge of AChE contains Trp in inhibitor-binding sites that might be targets for photo-oxidation. Indeed, reversible inhibitors retard photo-inactivation, and photo-inactivation destroys their binding sites. An excess of AChE protects paraoxonase from photo-inactivation by sequestering the photosensitizer. Affinity photo-oxidation of AChE by MB thus provides a valuable model for studying site-specific photo-inactivation of enzymes in both fundamental and clinical contexts. © 2010 The Authors. Photochemistry and Photobiology © 2010 The American Society of Photobiology.

  9. Integrated single- and two-photon light sheet microscopy using accelerating beams

    DEFF Research Database (Denmark)

    Piksarv, Peeter; Marti, Dominik; Le, Tuan

    2017-01-01

    We demonstrate the first light sheet microscope using propagation invariant, accelerating Airy beams that operates both in single- and two-photon modes. The use of the Airy beam permits us to develop an ultra compact, high resolution light sheet system without beam scanning. In two-photon mode, a...

  10. Spin polarization in top pair production in association with two photons at NLO+PS

    CERN Document Server

    Luisoni, Gionata

    2017-01-01

    This talk focuses on the impact of top-quark spin polarization effects in Higgs boson production in association with a top-quark pair, where the Higgs boson decays to two photons. Predictions for the signal are compared with direct top-quark pair production in association with two photons at NLO+PS.

  11. Two photon emission by hydrogen-like atoms in high temperature plasmas

    International Nuclear Information System (INIS)

    Costescu, A.; Manzatu, I.; Dinu, C.; Mihailescu, I.N.

    1981-08-01

    New exact solutions and a rather simple polynomial expression of the power emitted in the two photon transition from a metastable 2s state to the ground state of a hydrogen-like atom were infered with the aid of the Coulomb Green's function method. It was shown that the two photon decay represents under certain circumstances a significant power loss mechanism. (authors)

  12. Measurement and model of the infrared two-photon emission spectrum of GaAs.

    Science.gov (United States)

    Hayat, Alex; Ginzburg, Pavel; Orenstein, Meir

    2009-07-10

    Two-photon emission from semiconductors was recently observed, but not fully interpreted. We develop a dressed-state model incorporating intraband scattering-related level broadening, yielding nondivergent emission rates. The spectrum calculations for high carrier concentrations including the time dependence of the screening buildup correspond well to our measured two-photon emission spectrum from GaAs.

  13. Time gated fluorescence lifetime imaging and micro-volume spectroscopy using two-photon excitation

    NARCIS (Netherlands)

    Sytsma, J.; Vroom, J.M.; de Grauw, C.J.; Gerritsen, H.C.

    A scanning microscope utilizing two-photon excitation in combination with fluorescence lifetime contrast is presented. The microscope makes use of a tunable femtosecond titanium:sapphire laser enabling the two-photon excitation of a broad range of fluorescent molecules, including UV probes.

  14. Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles for two-photon photodynamic therapy or photoacoustic imaging.

    Science.gov (United States)

    Mauriello-Jimenez, Chiara; Henry, Maxime; Aggad, Dina; Raehm, Laurence; Cattoën, Xavier; Wong Chi Man, Michel; Charnay, Clarence; Alpugan, Serkan; Ahsen, Vefa; Tarakci, Deniz Kutlu; Maillard, Philippe; Maynadier, Marie; Garcia, Marcel; Dumoulin, Fabienne; Gary-Bobo, Magali; Coll, Jean-Luc; Josserand, Véronique; Durand, Jean-Olivier

    2017-11-09

    Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles (BSPOR and BSPHT) were prepared. Their endocytosis in MCF-7 cancer cells was shown with two-photon excited fluorescence (TPEF) imaging. With two-photon excited photodynamic therapy (TPE-PDT), BSPOR was more phototoxic than BSPHT, which in contrast displayed a very high signal for photoacoustic imaging in mice.

  15. Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

    Science.gov (United States)

    Wang, Xuhua; Yao, Sheng; Ahn, Hyo-Yang; Zhang, Yuanwei; Bondar, Mykhailo V.; Torres, Joseph A.; Belfield, Kevin D.

    2010-01-01

    Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated. PMID:21258480

  16. A new approach to dual-color two-photon microscopy with fluorescent proteins

    Directory of Open Access Journals (Sweden)

    Rebane Aleks

    2010-02-01

    Full Text Available Abstract Background Two-photon dual-color imaging of tissues and cells labeled with fluorescent proteins (FPs is challenging because most two-photon microscopes only provide one laser excitation wavelength at a time. At present, methods for two-photon dual-color imaging are limited due to the requirement of large differences in Stokes shifts between the FPs used and their low two-photon absorption (2PA efficiency. Results Here we present a new method of dual-color two-photon microscopy that uses the simultaneous excitation of the lowest-energy electronic transition of a blue fluorescent protein and a higher-energy electronic transition of a red fluorescent protein. Conclusion Our method does not require large differences in Stokes shifts and can be extended to a variety of FP pairs with larger 2PA efficiency and more optimal imaging properties.

  17. Highly sensitive measurement in two-photon absorption cross section and investigation of the mechanism of two-photon-induced polymerization

    International Nuclear Information System (INIS)

    Lu Youmei; Hasegawa, Fuyuki; Goto, Takamichi; Ohkuma, Satoshi; Fukuhara, Setsuko; Kawazu, Yukie; Totani, Kenro; Yamashita, Takashi; Watanabe, Toshiyuki

    2004-01-01

    A novel two-photon initiator, 4,4'-bis[4-(di-n-butylamino)styryl]-benzene with the side-group methyl (Me) (abbreviated as Chromophore 1), was synthesized in comparison with the chromophore with the side group methoxy (MeO) (abbreviated as Chromophore 2). Femtosecond laser-induced fluorescence intensity was used to evaluate two-photon absorption (TPA) cross section, δ, by means of a charge-coupled device, USB-2000 (abbreviated as CCD). Results showed that changing the side group from Me to MeO led to a significant red-shift of the two-photon absorption ( 2 λ max ). However, the microstructures obtained by two-photon-induced polymerization (TPIP) demonstrated that the sensitivities of Chromophore 1 increased despite a two-fold decrease in the two-photon cross section δ max, relative to Chromophore 2. Correlated with the appearance that the long-lived charge transfer emission of the chromophore in the monomer bulk, we suggest that the intramolecular charge transfer (intra-CT) takes place within the excited dye. Then intermolecular charge transfer was successive as a result of the formation of an exciplex between the dye and the monomer. The Me group was favorable for the intra-CT, relative to MeO, which contributed to the enhancement of the sensitivity of TPIP

  18. Development of Smart Phthalocyanine-based Photosensitizers for Photodynamic Therapy

    Science.gov (United States)

    Chow, Yun Sang

    are self-quenched, but separated and activated after cleavage of the acetal linkages. The basic photophysical properties, activation behavior in fluorescence emission, singlet oxygen generation, and in vitro photodynamic activities of this compound have been investigated and compared with those of the non-cleavable analogue. The activation of this tetramer has been demonstrated in the aqueous medium and at the cellular level, in which the fluorescence emission and photosensitizing ability can be greatly enhanced. This tetramer exhibits low dark toxicity and enhanced cytotoxicity upon illumination toward the HT29 human colon adenocarcinoma cells. Glutathione (GSH) is another well-documented stimulus for the design of activatable photosensitizers. It is the most abundant biological thiol which acts as the reducing agent in many biochemical processes. The much higher intracellular GSH concentration compared with the extracellular GSH level provides an activation mechanism. By using this feature, we have developed a series of GSH-responsive phthalocyanine dendrons in order to optimize the molecular design of self-quenched activatable photosensitizers. The aggregation tendency and the activation behavior in fluorescence emission and singlet oxygen generation in aqueous media have been investigated. The in vitro properties of the phthalocyanine dendrons including relative intracellular fluorescence and photocytotoxicity are also examined and presented in Chapter 3.. Chapter 4 reports the molecular design and synthesis of a biotin-decorated GSH-responsive zinc(II) phthalocyanine trimer, in which the phthalocyanine units are severely self-quenched, but are separated and then activated upon cleavage of the disulfide bondings by GSH. The basic photophysical properties, cleavage kinetics, and activation behavior in fluorescence and photosensitizing ability of this compound have been investigated. Its in vitro photodynamic activity, cellular uptake by different cell lines, and

  19. Modulation of the Singlet Oxygen Generation from the Double Strand DNA-SYBR Green I Complex Mediated by T-Melamine-T Mismatch for Visual Detection of Melamine.

    Science.gov (United States)

    Hu, Hao; Zhang, Jinyi; Ding, Yu; Zhang, Xinfeng; Xu, Kailai; Hou, Xiandeng; Wu, Peng

    2017-05-02

    Singlet oxygen ( 1 O 2 ), generated via photosensitization, has been proved to oxidize chromogenic substrates with neither H 2 O 2 oxidation nor enzyme (horseradish peroxidase, HRP) catalysis. Of the various methods for modulation of the 1 O 2 generation, DNA-controlled photosensitization received great attention. Therefore, integration of the formation/deformation DNA structures with DNA-controlled photosensitization will be extremely appealing in visual biosensor developments. Here, the stable melamine-thymine complex was explored in combination with DNA-controlled photosensitization for visual detection of melamine. A T-rich single stand DNA was utilized as the recognition unit. Upon the formation of the T-M-T complex, double stand DNA was formed, which was ready for the binding of SYBR Green I and activated the photosensitization. Subsequent oxidation of TMB allowed visual detection of melamine in dairy products, with spike-recoveries ranging from 94% to 106%.

  20. The (6-4) Dimeric Lesion as a DNA Photosensitizer.

    Science.gov (United States)

    Vendrell-Criado, Victoria; Rodríguez-Muñiz, Gemma M; Lhiaubet-Vallet, Virginie; Cuquerella, M Consuelo; Miranda, Miguel A

    2016-07-04

    Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1) , and a triplet-excited-state energy of 297 kJ mol(-1) . Its triplet transient absorption has a maximum at 420-440 nm, a lifetime of around 7 μs, and a high formation quantum yield, ΦISC =0.86. This species is efficiently quenched by thymidine. Its DNA photosensitizing properties are demonstrated by a series of experiments run on a pBR322 plasmid. The lesion photoinduces both single-strand breaks and the formation of cyclobutane thymine dimers. Altogether, these results show that, the substitution of the pyrimidone ring at C4 by a 5-hydroxy-5,6-dihydrothymine does not cancel out the photosensitization properties of the chromophore. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Photosensitizer-gold nanorod composite for targeted multimodal therapy.

    Science.gov (United States)

    Wang, Jian; You, Mingxu; Zhu, Guizhi; Shukoor, Mohammed Ibrahim; Chen, Zhuo; Zhao, Zilong; Altman, Meghan B; Yuan, Quan; Zhu, Zhi; Chen, Yan; Huang, Cheng Zhi; Tan, Weihong

    2013-11-11

    In this work, a DNA inter-strand replacement strategy for therapeutic activity is successfully designed for multimodal therapy. In this multimodal therapy, chlorin e6 (Ce6) photosensitizer molecules are used for photodynamic therapy (PDT), while aptamer-AuNRs, are used for selective binding to target cancer cells and for photothermal therapy (PTT) with near infrared laser irradiation. Aptamer Sgc8, which specifically targets leukemia T cells, is conjugated to an AuNR by a thiol-Au covalent bond and then hybridized with a Ce6-labeled photosensitizer/reporter to form a DNA double helix. When target cancer cells are absent, Ce6 is quenched and shows no PDT effect. However, when target cancer cells are present, the aptamer changes structure to release Ce6 to produce singlet oxygen for PDT upon light irradiation. Importantly, by combining photosensitizer and photothermal agents, PTT/PDT dual therapy supplies a more effective therapeutic outcome than either therapeutic modality alone. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Two-photon absorption and two-photon circular dichroism of L-tryptophan in the near to far UV region

    Science.gov (United States)

    Vesga, Yuly; Hernandez, Florencio E.

    2017-09-01

    Herein we report on the first measurements of the two-photon absorption (TPA) spectrum of L-tryptophan in DMSO solution in the near to far UV region and the two-photon circular dichroism (TPCD) signal corresponding to a transition at 200 nm. We demonstrate the application of the Double L-scan technique in the near to far UV region to perform polarization dependent TPA measurements of chiral molecules. TPCD measurements below 400 nm reveal that chiral molecules in solution, such as tryptophan/DMSO, can undergo photochemical reactions in front of prolonged exposure to UV radiation.

  3. Photosensitizer-conjugated tryptophan-containing peptide ligands as new dual-targeted theranostics for cancers.

    Science.gov (United States)

    Kim, Jisu; Chae, Jihyun; Kim, Jun Soo; Goh, Sung-Ho; Choi, Yongdoo

    2016-11-20

    Here we report that new dual-targeted theranostic anti-cancer agents can be produced by simple conjugation of photosensitizers with tryptophan-containing peptide ligands via cyclic disulfide linkages. In the proof-of-concept study, photosensitizers conjugated with EGFR-targeting peptide GE11 (C-EGFR) were in close proximity with tryptophan residues in the conjugate, resulting in quenching of its fluorescence and singlet oxygen generation. C-EGFR specifically binds to target receptors on the cancer cell surface, after which it is internalized via receptor-mediated endocytosis. Intracellular cleavage of cyclic disulfide bonds allows separation of the photosensitizers from the tryptophan residue, after which they emit near-infrared (NIR) fluorescence and produce a phototoxic effect in the target cells. This strategy enabled us to accomplish simultaneous real-time NIR fluorescence imaging of EGFR-overexpressing cancer cells with high contrast and selective photodynamic therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Singlet-Oxygen Generation From Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Bennett E.; Roder, Paden B.; Hanson, Jennifer L.; Manandhar, Sandeep; Devaraj, Arun; Perea, Daniel E.; Kim, Woo-Joong; Kilcoyne, Arthur L.; Pauzauskie, Peter J.

    2015-03-13

    Photodynamic therapy has been used for several decades in the treatment of solid tumors through the generation of reactive singlet-oxygen species (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trap also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications in understanding the impact of 1O2 on individual cancer cells.

  5. Parameter determination for singlet oxygen modeling of BPD-mediated PDT

    Science.gov (United States)

    McMillan, Dayton D.; Chen, Daniel; Kim, Michele M.; Liang, Xing; Zhu, Timothy C.

    2013-03-01

    Photodynamic therapy (PDT) offers a cancer treatment modality capable of providing minimally invasive localized tumor necrosis. To accurately predict PDT treatment outcome based on pre-treatment patient specific parameters, an explicit dosimetry model is used to calculate apparent reacted 1O2 concentration ([1O2]rx) at varied radial distances from the activating light source inserted into tumor tissue and apparent singlet oxygen threshold concentration for necrosis ([1O2]rx, sd) for type-II PDT photosensitizers. Inputs into the model include a number of photosensitizer independent parameters as well as photosensitizer specific photochemical parameters ξ σ, and β. To determine the specific photochemical parameters of benzoporphyrin derivative monoacid A (BPD), mice were treated with BPDPDT with varied light source strengths and treatment times. All photosensitizer independent inputs were assessed pre-treatment and average necrotic radius in treated tissue was determined post-treatment. Using the explicit dosimetry model, BPD specific ξ σ, and β photochemical parameters were determined which estimated necrotic radii similar to those observed in initial BPD-PDT treated mice using an optimization algorithm that minimizes the difference between the model and that of the measurements. Photochemical parameters for BPD are compared with those of other known photosensitizers, such as Photofrin. The determination of these BPD specific photochemical parameters provides necessary data for predictive treatment outcome in clinical BPD-PDT using the explicit dosimetry model.

  6. Facile synthesis of two-photon absorbing polymers through radical copolymerization

    Directory of Open Access Journals (Sweden)

    2007-08-01

    Full Text Available A two-photon absorbing polymer has been prepared through radical copolymerization of methyl acrylate and a synthesized monomer containing a two-photon absorbing chromophore (E,E,E-1,3,5-tristyrylbenzene (1, under conventional radical polymerization conditions. The synthesized polymer was characterized by nuclear magnetic resonance (NMR, infra-red spectroscopy (IR and gel permeation chromatography (GPC. The linear and nonlinear optical properties were studied by measurement of UV-Vis absorption, fluorescent emission and two-photon cross-section. This synthetic strategy provided a facile approach for synthesis of photonic materials with adjustable chromophore concentration and high molecular weights.

  7. The two-photon exchange contribution to elastic electron-nucleon scattering at large momentum transfer

    Energy Technology Data Exchange (ETDEWEB)

    Andrei V. Afanasev; Stanley J. Brodsky; Carl E. Carlson; Yu-Chun Chen; Marc Vanderhaeghen

    2005-01-01

    We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to the generalized parton distributions which also enter in other wide angle scattering processes. We find that the interference of one- and two-photon exchange contribution is able to substantially resolve the difference between electric form factor measurements from Rosenbluth and polarization transfer experiments.

  8. Dicke coherent narrowing in two-photon and Raman spectroscopy of thin vapor cells

    International Nuclear Information System (INIS)

    Dutier, Gabriel; Todorov, Petko; Hamdi, Ismahene; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel; Ducloy, Martial

    2005-01-01

    The principle of coherent Dicke narrowing in a thin vapor cell, in which sub-Doppler spectral line shapes are observed under a normal irradiation for a λ/2 thickness, is generalized to two-photon spectroscopy. Only the sum of the two wave vectors must be normal to the cell, making the two-photon scheme highly versatile. A comparison is provided between the Dicke narrowing with copropagating fields, and the residual Doppler broadening occurring with counterpropagating geometries. The experimental feasibility is discussed on the basis of a first observation of a two-photon resonance in a 300-nm-thick Cs cell. Extension to the Raman situation is finally considered

  9. A compact two photon light sheet microscope for applications in neuroscience

    DEFF Research Database (Denmark)

    Piksarv, Peeter; Marti, Dominik; Le, Tuan

    2016-01-01

    We present a compact setup for two photon light sheet microscopy. By using pulsed Airy beam illumination we demonstrate eight-fold increase of the FOV compared to Gaussian light sheet with the same axial resolution....

  10. The Two-Photon Exchange Contribution to Elastic Electron-Nucleon Scattering at Large Momentum Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Afanasev, A.

    2005-02-02

    We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to the generalized parton distributions which also enter in other wide angle scattering processes. We find that the interference of one- and two-photon exchange contribution is able to substantially resolve the difference between electric form factor measurements from Rosenbluth and polarization transfer experiments. Two-photon exchange has additional consequences which could be experimentally observed, including nonzero polarization effects and a positron-proton/electron-proton scattering asymmetry. The predicted Rosenbluth plot is no longer precisely linear; it acquires a measurable curvature, particularly at large laboratory angle.

  11. Simple fibre based dispersion management for two-photon excited fluorescence imaging through an endoscope

    DEFF Research Database (Denmark)

    Dimopoulos, Konstantinos; Marti, Dominik; Andersen, Peter E.

    2018-01-01

    We want to implement two-photon excitation fluorescence microscopy (TPEFM) into endoscopes, since TPEFM can provide relevant biomarkers for cancer staging and grading in hollow organs, endoscopically accessible through natural orifices. However, many obstacles must be overcome, among others...

  12. Photophysical processes in electronic states of zinc tetraphenyl porphyrin accessed on one- and two-photon excitation in the soret region

    International Nuclear Information System (INIS)

    Lukaszewicz, Adam; Karolczak, Jerzy; Kowalska, Dorota; Maciejewski, Andrzej; Ziolek, Marcin; Steer, Ronald P.

    2007-01-01

    Photophysical processes in the model metalloporphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP), have been investigated by means of conventional electronic spectroscopy, and by picosecond transient emission and femtosecond transient absorption methods. The radiative and radiationless decay parameters of ZnTPP have been determined under conditions of low solute concentration where dimer formation is unimportant, and the effects of dimer formation at higher concentrations have been assessed. Careful measurements of the relative S 1 -S 0 fluorescence quantum yields produced on excitation to higher states compared with direct excitation to S 1 itself reveal that a second radiationless decay process that bypasses S 1 operates when ZnTPP is excited in the Soret region. A dark state, assigned most probably to a triplet (T n , n > 2) or an upper singlet of gerade parity, is involved. The relative importance of this second process is a function of the nature of the solvent, the excitation wavelength (vibrational energy content of the excited state) and the parity of higher electronic states accessed when two-photon excitation is employed. Sequential two-photon excitation occurs when exciting with fs pulses in the Soret region and becomes significant at even modest excitation pulse energies with increasing sample absorbance. The implications of these measurements in reinterpreting the dynamics of electronically excited ZnTPP are discussed

  13. Two-photon free-free transitions in laser-assisted electron-hydrogen scattering

    International Nuclear Information System (INIS)

    Kracke, G.; Briggs, J.S.; Dubois, A.; Maquet, A.; Veniard, V.

    1994-01-01

    We present a perturbative calculation of the cross section for two-photon free-free transitions in laser assisted electron-hydrogen scattering within the first Born approximation. The virtual one- and two-photon excitations of the hydrogen atom during the scattering event are taken into account explicitly and their importance is demonstrated for the special case of the hydrogen atom remaining in its ground state after the collision. (Author)

  14. Selection rules for the dematerialization of a particle into two photons

    International Nuclear Information System (INIS)

    Yang, C.N.

    1983-01-01

    Selection rules governing the disintegration of a particle into two photons are derived from the general principle of invariance under rotation and inversion. The polarization state of the photons is completely fixed by the selection rules for initial particles with spin less than 2. These results which are independent of any specific assumption about the interactions may possibly offer a method of deciding the symmetry nature of mesons which decay into two photons. 4 tables

  15. Influence of Two Photon Absorption on Soliton Self-Frequency Shift

    DEFF Research Database (Denmark)

    Steffensen, Henrik; Rottwitt, Karsten; Jepsen, Peter Uhd

    2011-01-01

    The creation of mid-infrared supercontinua necessitates the use of soft-glass fibers. However, some materials, like chalcogenide, have a substantial two photon absorption. We introduce a model for soliton self-frequency shift that successfully includes this effect.......The creation of mid-infrared supercontinua necessitates the use of soft-glass fibers. However, some materials, like chalcogenide, have a substantial two photon absorption. We introduce a model for soliton self-frequency shift that successfully includes this effect....

  16. Event-by-event simulation of nonclassical effects in two-photon interference experiments

    OpenAIRE

    Michielsen, Kristel; Jin, Fengping; Delina, Mutia; De Raedt, Hans

    2012-01-01

    A corpuscular simulation model for second-order intensity interference phenomena is discussed. It is shown that both the visibility ${\\cal V}=1/2$ predicted for two-photon interference experiments with two independent sources and the visibility ${\\cal V}=1$ predicted for two-photon interference experiments with a parametric down-conversion source can be explained in terms of a locally causal, modular, adaptive, corpuscular, classical (non-Hamiltonian) dynamical system. Hence, there is no need...

  17. Suppression of two-photon resonantly enhanced nonlinear processes in extended media

    International Nuclear Information System (INIS)

    Garrett, W.R.; Moore, M.A.; Payne, M.G.; Wunderlich, R.K.

    1988-11-01

    On the basis of combined experimental and theoretical studies of nonlinear processes associated with two-photon excitations near 3d and 4d states in Na, we show how resonantly enhanced stimulated hyper-Raman emission, parametric four-wave mixing processes and total resonant two-photon absorption can become severely suppressed through the actions of internally generated fields on the total atomic response in extended media. 7 refs., 3 figs

  18. Saturated two-photon absorption by atoms in a perturber gas

    International Nuclear Information System (INIS)

    Nienhuis, G.

    1980-01-01

    We derive a general expression for the two-photon absorption spectrum of a three-state atom excited by two mono-chromatic radiation fields. Collisional line-broadening effects are incorporated, and the result allows inclusion of profiles with a validity outside the impact limit. Results of previous work are recovered in the appropriate limits. Saturation affects the different lines in the two-photon absorption spectrum in a different fashion. (orig.)

  19. Ocular Defects in Photosensitive Epilepsy

    Directory of Open Access Journals (Sweden)

    Ebere C. Anyanwu

    2004-01-01

    Full Text Available Patients with photosensitive epilepsy are susceptible to seizures due to photoparoxysmal response (PPR. This response adversely precipitates factors that modify the functional status of the visual system. Such factors may or may not be evident superficially, but may lead to ocular defects due to trauma, hormonal imbalance, abnormal intraocular pressure (IOP, or any other reflex-inducing stimuli. The extent to which photosensitive epileptic patients suffer from PPR-related ocular defects has not been documented fully. In this investigation, ocular defects in patients with photosensitive epilepsy are studied using visual-evoked response (VER. A total of 212 photosensitive epileptic patients were studied to ascertain the magnitude and distribution of ocular defects using the changes in EEG and visual-evoked potential (VEP; 51% of the patients were female, the age range was 1–46 years. The major ocular defects and complications found were visual field defects, optic nerve abnormalities, nystagmus, cataracts, amblyopia, and migraine. These findings were analyzed according to age and sex. The relationship between the ocular abnormalities and the interpretations of the changes in the characteristics of the VEP indicated that optic-related atrophies, visual defects, optic neuritis, chiasmal compression, nystagmus, migraine headache, cataracts, and amblyopia were prevalent in photosensitive epileptic patients at varying degrees. The results showed that although ocular defects in photosensitive epilepsy may not be obvious differentially, VEP can be used in their diagnosis, contrary to earlier studies reporting that VEP is not of much value in epilepsy diagnosis.

  20. Denoising of two-photon fluorescence images with block-matching 3D filtering.

    Science.gov (United States)

    Danielyan, Aram; Wu, Yu-Wei; Shih, Pei-Yu; Dembitskaya, Yulia; Semyanov, Alexey

    2014-07-01

    Two-photon florescence imaging is widely used to perform morphological analysis of subcellular structures such as neuronal dendrites and spines, astrocytic processes etc. This method is also indispensable for functional analysis of cellular activity such as Ca2+ dynamics. Although spatial resolution of laser scanning two-photon system is greater than that of confocal or wide field microscope, it is still diffraction limited. In practice, the resolution of the system is more affected by its signal-to-noise ratio (SNR) than the diffraction limit. Thus, various approaches aiming to increase the SNR in two-photon imaging are desirable and can potentially save on building costly super-resolution imaging system. Here we analyze the statistics of noise in the two-photon florescence images of hippocampal astrocytes expressing genetically encoded Ca2+ sensor GCaMP2 and show that it can be reasonably well approximated using the same models which are used for describing noise in images acquired with digital cameras. This allows to use denoising methods available for wide field imaging on two-photon images. Particularly we demonstrate that the Block-Matching 3D (BM3D) filter can significantly improve the quality of two-photon fluorescence images so small details such as astrocytic processes can be easier identified. Moreover, denoising of the images with BM3D yields less noisy Ca2+ signals in astrocytes when denoising of the images with Gaussian filter. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Explicit macroscopic singlet oxygen modeling for benzoporphyrin derivative monoacid ring A (BPD)-mediated photodynamic therapy.

    Science.gov (United States)

    Kim, Michele M; Penjweini, Rozhin; Liang, Xing; Zhu, Timothy C

    2016-11-01

    Photodynamic therapy (PDT) is an effective non-ionizing treatment modality that is currently being used for various malignant and non-malignant diseases. In type II PDT with photosensitizers such as benzoporphyrin monoacid ring A (BPD), cell death is based on the creation of singlet oxygen ( 1 O 2 ). With a previously proposed empirical five-parameter macroscopic model, the threshold dose of singlet oxygen ([ 1 O 2 ] rx,sh ]) to cause tissue necrosis in tumors treated with PDT was determined along with a range of the magnitude of the relevant photochemical parameters: the photochemical oxygen consumption rate per light fluence rate and photosensitizer concentration (ξ), the probability ratio of 1 O 2 to react with ground state photosensitizer compared to a cellular target (σ), the ratio of the monomolecular decay rate of the triplet state photosensitizer (β), the low photosensitizer concentration correction factor (δ), and the macroscopic maximum oxygen supply rate (g). Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated interstitially with a linear light source at 690nm with total energy released per unit length of 22.5-135J/cm and source power per unit length of 12-150mW/cm to induce different radii of necrosis. A fitting algorithm was developed to determine the photochemical parameters by minimizing the error function involving the range between the calculated reacted singlet oxygen ([ 1 O 2 ] rx ) at necrosis radius and the [ 1 O 2 ] rx,sh . [ 1 O 2 ] rx was calculated based on explicit dosimetry of the light fluence distribution, the tissue optical properties, and the BPD concentration. The initial ground state oxygen concentration ([ 3 O 2 ] 0 ) was set to be 40μM in this study. The photochemical parameters were found to be ξ=(55±40)×10 -3 cm 2 mW -1 s -1 , σ=(1.8±3)×10 -5 μM -1 , and g=1.7±0.7μMs -1 . We have taken the literature values for δ=33μM, and β=11.9μM. [ 1 O 2 ] rx has shown promise to be a more effective

  2. Receptor-targeting phthalocyanine photosensitizer for improving antitumor photocytotoxicity.

    Science.gov (United States)

    Xu, Peng; Chen, Jincan; Chen, Zhuo; Zhou, Shanyong; Hu, Ping; Chen, Xueyuan; Huang, Mingdong

    2012-01-01

    Photodynamic therapy (PDT) is a promising therapeutic modality which uses a photosensitizer to capture visible light resulting in phototoxicity in the irradiated region. PDT has been used in a number of pathological indications, including tumor. A key desirable feature of the photosensitizer is the high phototoxicity on tumor cells but not on normal cells. In this study, we conjugate a gonadotropin-releasing hormone (GnRH) to a photosensitizer, Zinc phthalocyanine (ZnPc), in order to enhance its specificity to breast cancer, which over-expresses GnRH receptor. ZnPc has unique advantages over other photosensitizers, but is difficult to derivatize and purify as a single isomer. We previously developed a straight-forward way to synthesize mono-substituted β-carboxy-phthalocyanine zinc (ZnPc-COOH). Photophysical and photochemical parameters of this ZnPc-GnRH conjugate including fluorescence quantum yield (Ф(f)), fluorescence decay time (τ(s)) and singlet oxygen quantum yield (Ф(Δ)) were evaluated and found comparable with that of ZnPc, indicating that addition of a GnRH peptide does not significantly alter the generation of singlet oxygen from ZnPc. Cellular uptakes and phototoxicities of this conjugate were tested and found significantly enhanced on human breast cancer cell lines overexpressing GnRH receptors (MDA-MB-231 and MCF-7 cells) compared to cells with low levels of GnRH receptors, such as human embryonic lung fibroblast (HELF) and human liver carcinoma (HepG2) cells. In addition, the cellular uptake of this conjugate toward MCF-7 cells were found clearly alleviated by a GnRH receptor blocker Cetrorelix, suggesting that the cellular uptake of this conjugate was GnRH receptor-mediated. Put together, these findings revealed that coupling ZnPc with GnRH analogue was an effective way to improve the selectivity of ZnPc towards tumors with over-expressed GnRH receptors.

  3. Glow discharge in singlet oxygen

    International Nuclear Information System (INIS)

    Vagin, N.P.; Ionin, A.A.; Klimachev, Yu.M.; Sinitsyn, D.V.; Yuryshev, N.N.; Kochetov, I.V.; Napartovich, A.P.

    2003-01-01

    Currently, there is no experimental data on the plasma balance in gas mixtures with a high content of singlet delta oxygen O 2 ( 1 Δ g ). These data can be obtained by studying the parameters of an electric discharge in singlet oxygen produced by a chemical generator. The O 2 ( 1 Δ g ) molecules significantly change the kinetics of electrons and negative ions in plasma. Hence, the discharge conditions at low and high O 2 ( 1 Δ g ) concentrations are very different. Here, the parameters of the positive column of a glow discharge in a gas flow from a chemical singlet-oxygen generator are studied. It is experimentally shown that, at an O 2 ( 1 Δ g ) concentration of 50% and at pressures of 1.5 and 2 torr, the electric field required to sustain the discharge is considerably lower than in the case when all of the oxygen molecules are in the ground state. A theoretical model of the glow discharge is proposed whose predictions are in good agreement with the experimental data

  4. Photobleaching-induced changes in photosensitizing properties of dissolved organic matter

    KAUST Repository

    Niu, Xi-Zhi

    2014-12-01

    Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen (1O2), triplet state of DOM (3DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching.

  5. Pyridinium-Substituted TetraphenylethyleneEntailing Alkyne Moiety: Enhancement of Photosensitizing Efficiency and Antimicrobial Activity.

    Science.gov (United States)

    You, Xue; Ma, Huili; Wang, Yuancheng; Zhang, Guanxin; Peng, Qian; Liu, Libing; Wang, Shu; Zhang, Deqing

    2017-05-04

    Apart from sensing and imaging, luminogens with aggregation-induced emission (AIE) are also interesting for photosensitizing. The photosensitizing behavior and bacteria-killing performance of a pyridinium-substituted tetraphenylethylene with an alkyne group (TPE-A-Py + ) is reported herein. Interestingly, TPE-A-Py + exhibits higher photosensitizing efficiency than TPE-Py + (without alkyne group) when I - was used as a counteranion. This is well explained by the fact that the ΔΕ ST between the excited singlet state (S 1 ) and triplet state (T 1 ) was lower for TPE-A-Py + than for TPE-Py + , according to theoretical calculations. Moreover, replacement of I - with other anions (PF 6 - , N(SO 2 CF 3 ) 2 - and BPh 4 - ) led to a decrease of photosensitizing efficiency for TPE-A-Py + . Notably, TPE-A-Py + could be used as an efficient photosensitizer to photo-inactivate ampicillin-resistant (amp r ) E. coli at low concentration under white-light irradiation very quickly. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Photosensitizing effectiveness of a novel chlorin-based photosensitizer for photodynamic therapy in vitro and in vivo.

    Science.gov (United States)

    Zhang, Li-Jun; Bian, Jun; Bao, Lei-Lei; Chen, Hai-Fei; Yan, Yi-Jia; Wang, Li; Chen, Zhi-Long

    2014-09-01

    Photodynamic therapy (PDT) is a promising noninvasive treatment, which has been approved by the US Food and Drug Administration for the treatment of localized tumors. With the aim to select an appropriate photosensitizer for tumor treatment in PDT, the antitumor effect of a novel chlorin-based photosensitizer, meso-tetra (3-morphlinomethyl-4-methoxyphenyl) chlorin (TMMC) (Fig. 1a) on two types of human malignant tumor cells in vitro and a esophageal cancer model in nude mice, was evaluated in the present paper. Fig. 1 Chemical structure and spectrum properties of TMMC in DMF. a Chemical structure of TMMC in DMF. b UV-Vis absorption spectrum of TMMC in DMF. Its maximum absorbance is at 423 nm, and at 527, 555, 600, 655 nm and 712 nm, also it has absorption. c Emission spectrum of TMMC, which was excited at 514 nm, and its peaks were at 656 and 720 nm. d The matrix of excitation and emission spectra (Ex: 300-550 nm, Em: 600-780 nm) The efficiency of TMMC-PDT in vitro was analyzed by MTT assay and clonogenic assay. The intracellular distribution of photosensitizers was detected with laser scanning confocal microscopy. The accumulation of TMMC in human malignant tumor cells was measured by Fluorescence Spectrometer, and the pathway of cell death was analyzed by flow cytometry. Eca-109 tumor model was used to evaluate the antitumor effects of TMMC-mediated PDT. And the singlet oxygen quantum yield of TMMC was also measured using DPBF as substrate. TMMC shows a singlet oxygen quantum yield of 0.59 and displays a characteristic long wavelength absorption peak at 655 nm. The accumulation of TMMC increased in time-dependent manner, and it was found in cytoplasm and nuclear membranes. TMMC-PDT induced cell death by the major death pathway of necrosis and significantly reduced the growth of Eca-109 tumors in nude mice (180 mW/cm(2), 120 J/cm(2)). The studies suggest that TMMC is an effective photosensitizer for PDT to tumors. Therefore, TMMC has great potentials

  7. Photosensitized Oxygenations of Hexamethylbenzene in Phase Contact Enhanced Microreactor

    International Nuclear Information System (INIS)

    Park, Chan Yi; Park, Jeong Hyeon; Lim Hyo Jin; Hwang, Geumsook; Park, Chan Pil

    2014-01-01

    Activated singlet oxygen ( 1 O 2 ) has successfully been utilized in production of various compounds including fragrances, pharmaceuticals, and fine chemicals. However, the traditional reaction required a prolonged reaction time due to the difficulty of introducing adequate light and oxygen into the solution. Low contact probability between four species of oxygen, photosensitizer, light, and reagent is an inherent drawback of the traditional photoreaction. Molecular diffusion distance is the most important factor in the heterogeneous reactions including gas-liquid, gassolid, liquid-solid, and immiscible liquid-liquid. Therefore, rates of reaction are closely depended on the distance. Microreactor has provided a distinct advantage in the short molecular diffusion distance due to the high surface-to-volume ratio driven by narrow fluidic channels

  8. Photosensitized Oxygenations of Hexamethylbenzene in Phase Contact Enhanced Microreactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Yi; Park, Jeong Hyeon; Lim Hyo Jin; Hwang, Geumsook; Park, Chan Pil [Chungnam National Univ., Daejeon (Korea, Republic of)

    2014-04-15

    Activated singlet oxygen ({sup 1}O{sub 2}) has successfully been utilized in production of various compounds including fragrances, pharmaceuticals, and fine chemicals. However, the traditional reaction required a prolonged reaction time due to the difficulty of introducing adequate light and oxygen into the solution. Low contact probability between four species of oxygen, photosensitizer, light, and reagent is an inherent drawback of the traditional photoreaction. Molecular diffusion distance is the most important factor in the heterogeneous reactions including gas-liquid, gassolid, liquid-solid, and immiscible liquid-liquid. Therefore, rates of reaction are closely depended on the distance. Microreactor has provided a distinct advantage in the short molecular diffusion distance due to the high surface-to-volume ratio driven by narrow fluidic channels.

  9. Pseudopotential calculations and photothermal lensing measurements of two-photon absorption in solids

    International Nuclear Information System (INIS)

    White, W.T. III.

    1985-01-01

    We have studied two-photon absorption in solids theoretically and experimentally. We have shown that it is possible to use accurate band structure techniques to compute two-photon absorption spectra within 15% of measured values in a wide band-gap material, ZnS. The empirical pseudopotential technique that we used is significantly more accurate than previous models of two-photon absorption in zinc blende materials, including present tunneling theories (which are essentially parabolic-band results in disguise) and the nonparabolic-band formalism of Pidgeon et al. and Weiler. The agreement between our predictions and previous measurements allowed us to use ZnS as a reference material in order to validate a technique for measuring two-photon absorption that was previously untried in solids, pulsed dual-beam thermal lensing. With the validated technique, we examined nonlinear absorption in one other crystal (rutile) and in several glasses, including silicates, borosilicates, and one phosphate glass. Initially, we believed that the absorption edges of all the materials were comparable; however, subsequent evidence suggested that the effective band-gap energies of the glasses were above the energy of two photons in our measurement. Therefore, we attribute the nonlinear absorption that we observed in glasses to impurities or defects. The measured nonlinear absorption coefficients were of the order of a few cm/TW in the glasses and of the order of 10 cm/GW in the crystals, four orders of magnitude higher than in glasses. 292 refs

  10. Pseudopotential calculations and photothermal lensing measurements of two-photon absorption in solids

    Energy Technology Data Exchange (ETDEWEB)

    White, W.T. III

    1985-11-04

    We have studied two-photon absorption in solids theoretically and experimentally. We have shown that it is possible to use accurate band structure techniques to compute two-photon absorption spectra within 15% of measured values in a wide band-gap material, ZnS. The empirical pseudopotential technique that we used is significantly more accurate than previous models of two-photon absorption in zinc blende materials, including present tunneling theories (which are essentially parabolic-band results in disguise) and the nonparabolic-band formalism of Pidgeon et al. and Weiler. The agreement between our predictions and previous measurements allowed us to use ZnS as a reference material in order to validate a technique for measuring two-photon absorption that was previously untried in solids, pulsed dual-beam thermal lensing. With the validated technique, we examined nonlinear absorption in one other crystal (rutile) and in several glasses, including silicates, borosilicates, and one phosphate glass. Initially, we believed that the absorption edges of all the materials were comparable; however, subsequent evidence suggested that the effective band-gap energies of the glasses were above the energy of two photons in our measurement. Therefore, we attribute the nonlinear absorption that we observed in glasses to impurities or defects. The measured nonlinear absorption coefficients were of the order of a few cm/TW in the glasses and of the order of 10 cm/GW in the crystals, four orders of magnitude higher than in glasses. 292 refs.

  11. Molecular engineering of two-photon fluorescent probes for bioimaging applications

    Science.gov (United States)

    Liu, Hong-Wen; Liu, Yongchao; Wang, Peng; Zhang, Xiao-Bing

    2017-03-01

    During the past two decades, two-photon microscopy (TPM), which utilizes two near-infrared photons as the excitation source, has emerged as a novel, attractive imaging tool for biological research. Compared with one-photon microscopy, TPM offers several advantages, such as lowering background fluorescence in living cells and tissues, reducing photodamage to biosamples, and a photobleaching phenomenon, offering better 3D spatial localization, and increasing penetration depth. Small-molecule-based two-photon fluorescent probes have been well developed for the detection and imaging of various analytes in biological systems. In this review, we will give a general introduction of molecular engineering of two-photon fluorescent probes based on different fluorescence response mechanisms for bioimaging applications during the past decade. Inspired by the desired advantages of small-molecule two-photon fluorescent probes in biological imaging applications, we expect that more attention will be devoted to the development of new two-photon fluorophores and applications of TPM in areas of bioanalysis and disease diagnosis.

  12. Enhanced Size Selection in Two-Photon Excitation for CsPbBr3 Perovskite Nanocrystals.

    Science.gov (United States)

    Chen, Junsheng; Chábera, Pavel; Pascher, Torbjörn; Messing, Maria E; Schaller, Richard; Canton, Sophie; Zheng, Kaibo; Pullerits, Tõnu

    2017-10-19

    Cesium lead bromide (CsPbBr 3 ) perovskite nanocrystals (NCs), with large two-photon absorption (TPA) cross-section and bright photoluminescence (PL), have been demonstrated as stable two-photon-pumped lasing medium. With two-photon excitation, red-shifted PL spectrum and increased PL lifetime is observed compared with one-photon excitation. We have investigated the origin of such difference using time-resolved laser spectroscopies. We ascribe the difference to the enhanced size selection of NCs by two-photon excitation. Because of inherent nonlinearity, the size dependence of absorption cross-section under TPA is stronger. Consequently, larger size NCs are preferably excited, leading to longer excited-state lifetime and red-shifted PL emission. In a broad view, the enhanced size selection in two-photon excitation of CsPbBr 3 NCs is likely a general feature of the perovskite NCs and can be tuned via NC size distribution to influence their performance within NC-based nonlinear optical materials and devices.

  13. Photosensitive Epilepsy In Kashmir Valley

    Directory of Open Access Journals (Sweden)

    Saleem S M

    2003-01-01

    Full Text Available A random population of 618 people with epilepsy hailing from different parts of Kashmir valley was screened for photosensitivity both clinically and on a standard protocol of intermittent photic stimulation (IPS provoked EEG recordings. Six (0.9% patients with a mean age of 15+6.57 years were found to be photosensitive; five had generalized and one had absence seizures. The baseline EEG in all patients showed generalized epileptiform discharges. On IPS, similar EEG findings were obtained with a narrow range of stimulus frequency i.e. 7-12 cycles/sec. There appears to be a low prevalence of photo-sensitivity in our epileptic population, possibly related to genetic factors.

  14. Laser-induced generation of singlet oxygen and its role in the cerebrovascular physiology

    Science.gov (United States)

    Semyachkina-Glushkovskaya, O. V.; Sokolovski, S. G.; Goltsov, A.; Gekaluyk, A. S.; Saranceva, E. I.; Bragina, O. A.; Tuchin, V. V.; Rafailov, E. U.

    2017-09-01

    For over 55 years, laser technology has expanded from laboratory research to widespread fields, for example telecommunication and data storage amongst others. Recently application of lasers in biology and medicine presents itself as one of the emerging areas. In this review, we will outline the recent advances in using lasers for the generation of singlet oxygen, traditionally used to kill tumour cells or induce thrombotic stroke model due to damage vascular effects. Over the last two decade, completely new results on cerebrovascular effects of singlet oxygen generated during photodynamic therapy (PDT) have been shown alongside promising applications for delivery of drugs and nanoparticles into the brain for therapy of brain cancer. Furthermore, a ;gold key; has been found to overcome the limitations of PDT, such as low light penetration and high toxicity of photosensitizers, by direct generation of singlet oxygen using quantum-dot laser diodes emitting in the near infrared (NIR) spectral range. It is our motivation to highlight these pioneering results in this review, to improve understanding of the biological role of singlet oxygen and to provide new perspectives for improving clinical application of laser based therapy in further research.

  15. In vivo outcome study of BPD-mediated PDT using a macroscopic singlet oxygen model

    Science.gov (United States)

    Kim, Michele M.; Penjweini, Rozhin; Zhu, Timothy C.

    2015-03-01

    Macroscopic modeling of the apparent reacted singlet oxygen concentration ([1O2]rx) for use with photodynamic therapy (PDT) has been developed and studied for benzoporphryin derivative monoacid ring A (BPD), a common photosensitizer. The four photophysical parameters (ξ, σ, β, δ) and threshold singlet oxygen dose ([1O2]rx, sh) have been investigated and determined using the RIF model of murine fibrosarcomas and interstitial treatment delivery. These parameters are examined and verified further by monitoring tumor growth post-PDT. BPD was administered at 1 mg/kg, and mice were treated 3 hours later with fluence rates ranging between 75 - 150 mW/cm2 and total fluences of 100 - 350 J/cm2. Treatment was delivered superficially using a collimated beam. Changes in tumor volume were tracked following treatment. The tumor growth rate was fitted for each treatment condition group and compared using dose metrics including total light dose, PDT dose, and reacted singlet oxygen. Initial data showing the correlation between outcomes and various dose metrics indicate that reacted singlet oxygen serves as a good dosimetric quantity for predicting PDT outcome.

  16. The participation of singlet oxygen in a photocitotoxicity of extract from amazon plant to cancer cells

    Science.gov (United States)

    Tcibulnikova, Anna V.; Degterev, Igor A.; Bryukhanov, Valery V.; Roberto, Mantuanelly M.; Campos Pereira, F. D.; Marin-Morales, M. A.; Slezhkin, Vasily A.; Samusev, Ilya G.

    2018-01-01

    We have been searching for new photosensitizers (PS) for photodynamic therapy (PDT) of cancer based on extracts from Amazonian plants since 2009. In this paper, we demonstrate that, under certain conditions, the extract from fruits of the Amazonian palm Euterpe oleraceae (popular name Açaí) can serve as a PS for PDT treatment of murine breast cancer cells (4T1 cell line). We have been first to show directly that the photodynamic effect of plant PS is due to singlet oxygen.

  17. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  18. Highly selective population of two excited states in nonresonant two-photon absorption

    International Nuclear Information System (INIS)

    Zhang Hui; Zhang Shi-An; Sun Zhen-Rong

    2011-01-01

    A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization. (atomic and molecular physics)

  19. Images of photoreceptors in living primate eyes using adaptive optics two-photon ophthalmoscopy

    Science.gov (United States)

    Hunter, Jennifer J.; Masella, Benjamin; Dubra, Alfredo; Sharma, Robin; Yin, Lu; Merigan, William H.; Palczewska, Grazyna; Palczewski, Krzysztof; Williams, David R.

    2011-01-01

    In vivo two-photon imaging through the pupil of the primate eye has the potential to become a useful tool for functional imaging of the retina. Two-photon excited fluorescence images of the macaque cone mosaic were obtained using a fluorescence adaptive optics scanning laser ophthalmoscope, overcoming the challenges of a low numerical aperture, imperfect optics of the eye, high required light levels, and eye motion. Although the specific fluorophores are as yet unknown, strong in vivo intrinsic fluorescence allowed images of the cone mosaic. Imaging intact ex vivo retina revealed that the strongest two-photon excited fluorescence signal comes from the cone inner segments. The fluorescence response increased following light stimulation, which could provide a functional measure of the effects of light on photoreceptors. PMID:21326644

  20. Two-photon calcium imaging in mice navigating a virtual reality environment.

    Science.gov (United States)

    Leinweber, Marcus; Zmarz, Pawel; Buchmann, Peter; Argast, Paul; Hübener, Mark; Bonhoeffer, Tobias; Keller, Georg B

    2014-02-20

    In recent years, two-photon imaging has become an invaluable tool in neuroscience, as it allows for chronic measurement of the activity of genetically identified cells during behavior(1-6). Here we describe methods to perform two-photon imaging in mouse cortex while the animal navigates a virtual reality environment. We focus on the aspects of the experimental procedures that are key to imaging in a behaving animal in a brightly lit virtual environment. The key problems that arise in this experimental setup that we here address are: minimizing brain motion related artifacts, minimizing light leak from the virtual reality projection system, and minimizing laser induced tissue damage. We also provide sample software to control the virtual reality environment and to do pupil tracking. With these procedures and resources it should be possible to convert a conventional two-photon microscope for use in behaving mice.

  1. Polarization properties of optical phase conjugation by two-photon resonant degenerate four-wave mixing

    Science.gov (United States)

    Kauranen, Martti; Gauthier, Daniel J.; Malcuit, Michelle S.; Boyd, Robert W.

    1989-08-01

    We develop a semiclassical theory of the polarization properties of phase conjugation by two-photon resonant degenerate four-wave mixing. The theory includes the effects of saturation by the pump waves. We solve the density-matrix equations of motion in steady state for a nonlinear medium consisting of stationary atoms with a ground and excited state connected by two-photon transitions. As an illustration of the general results, we consider an S0-->S0 two-photon transition, which is known to lead to perfect polarization conjugation in the limit of third-order theory. We show that the fidelity of the polarization-conjugation process is degraded for excessively large pump intensities. The degradation can occur both due to transfer of population to the excited state and due to nonresonant Stark shifts. Theoretical results are compared to those of a recent experiment [Malcuit, Gauthier, and Boyd, Opt. Lett. 13, 663 (1988)].

  2. Scanless functional imaging of hippocampal networks using patterned two-photon illumination through GRIN lenses

    KAUST Repository

    Moretti, Claudio

    2016-09-12

    Patterned illumination through the phase modulation of light is increasingly recognized as a powerful tool to investigate biological tissues in combination with two-photon excitation and light-sensitive molecules. However, to date two-photon patterned illumination has only been coupled to traditional microscope objectives, thus limiting the applicability of these methods to superficial biological structures. Here, we show that phase modulation can be used to efficiently project complex two-photon light patterns, including arrays of points and large shapes, in the focal plane of graded index (GRIN) lenses. Moreover, using this approach in combination with the genetically encoded calcium indicator GCaMP6, we validate our system performing scanless functional imaging in rodent hippocampal networks in vivo ~1.2 mm below the brain surface. Our results open the way to the application of patterned illumination approaches to deep regions of highly scattering biological tissues, such as the mammalian brain.

  3. Visualization of two-photon Rabi oscillations in evanescently coupled optical waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Ornigotti, M; Valle, G Della; Fernandez, T Toney; Laporta, P; Longhi, S [Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano, Piazza L. da Vinci 32, I-20133 Milano (Italy); Coppa, A; Foglietti, V [Istituto di Fotonica e Nanotecnologie del CNR, sezione di Roma, Via Cineto Romano 42, 00156 Roma (Italy)], E-mail: longhi@fisi.polimi.it

    2008-04-28

    An optical analogue of two-photon Rabi oscillations, occurring in a three-level atomic or molecular system coherently driven by two detuned laser fields, is theoretically proposed and experimentally demonstrated using three evanescently coupled optical waveguides realized on an active glass substrate. The optical analogue stems from the formal analogy between spatial propagation of light waves in the three-waveguide structure and the coherent temporal evolution of populations in a three-level atomic medium driven by two laser fields under two-photon resonance. In our optical experiment, two-photon Rabi oscillations are thus visualized as a slow spatial oscillatory exchange of light power between the two outer waveguides of the structure with a small excitation of the central waveguide.

  4. Visualization of two-photon Rabi oscillations in evanescently coupled optical waveguides

    International Nuclear Information System (INIS)

    Ornigotti, M; Valle, G Della; Fernandez, T Toney; Laporta, P; Longhi, S; Coppa, A; Foglietti, V

    2008-01-01

    An optical analogue of two-photon Rabi oscillations, occurring in a three-level atomic or molecular system coherently driven by two detuned laser fields, is theoretically proposed and experimentally demonstrated using three evanescently coupled optical waveguides realized on an active glass substrate. The optical analogue stems from the formal analogy between spatial propagation of light waves in the three-waveguide structure and the coherent temporal evolution of populations in a three-level atomic medium driven by two laser fields under two-photon resonance. In our optical experiment, two-photon Rabi oscillations are thus visualized as a slow spatial oscillatory exchange of light power between the two outer waveguides of the structure with a small excitation of the central waveguide

  5. Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

    Energy Technology Data Exchange (ETDEWEB)

    Fedotov, I. V.; Doronina-Amitonova, L. V. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Kurchatov Institute National Research Center, Moscow (Russian Federation); Sidorov-Biryukov, D. A.; Fedotov, A. B. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Anokhin, K. V. [Kurchatov Institute National Research Center, Moscow (Russian Federation); P.K. Anokhin Institute of Normal Physiology, Russian Academy of Medical Sciences, Moscow (Russian Federation); Kilin, S. Ya. [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus); Sakoda, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Zheltikov, A. M. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Center of Photochemistry, Russian Academy of Sciences, ul. Novatorov 7a, Moscow 117421 (Russian Federation)

    2014-02-24

    Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

  6. Resonance enhancement of two photon absorption by magnetically trapped atoms in strong rf-fields

    Science.gov (United States)

    Chakraborty, A.; Mishra, S. R.

    2018-01-01

    Applying a many mode Floquet formalism for magnetically trapped atoms interacting with a polychromatic rf-field, we predict a large two photon transition probability in the atomic system of cold 87Rb atoms. The physical origin of this enormous increase in the two photon transition probability is due to the formation of avoided crossings between eigen-energy levels originating from different Floquet sub-manifolds and redistribution of population in the resonant intermediate levels to give rise to the resonance enhancement effect. Other exquisite features of the studied atom-field composite system include the splitting of the generated avoided crossings at the strong field strength limit and a periodic variation of the single and two photon transition probabilities with the mode separation frequency of the polychromatic rf-field. This work can find applications to characterize properties of cold atom clouds in the magnetic traps using rf-spectroscopy techniques.

  7. THz/Infrared Double Resonance Two-Photon Spectroscopy of HD+ for Determination of Fundamental Constants

    Directory of Open Access Journals (Sweden)

    Florin Lucian Constantin

    2017-10-01

    Full Text Available A double resonance two-photon spectroscopy scheme is discussed to probe jointly rotational and rovibrational transitions of ensembles of trapped HD+ ions. The two-photon transition rates and lightshifts are calculated with the two-photon tensor operator formalism. The rotational lines may be observed with sub-Doppler linewidth at the hertz level and good signal-to-noise ratio, improving the resolution in HD+ spectroscopy beyond the 10−12 level. The experimental accuracy, estimated at the 10−12 level, is comparable with the accuracy of theoretical calculations of HD+ energy levels. An adjustment of selected rotational and rovibrational HD+ lines may add clues to the proton radius puzzle, may provide an independent determination of the Rydberg constant, and may improve the values of proton-to-electron and deuteron-to-proton mass ratios beyond the 10−11 level.

  8. Investigating Photosensitized Properties of Natural Organic Matter and Effluent Organic Matter

    KAUST Repository

    Niu, Xi-Zhi

    2013-05-01

    The photosensitized processes significantly enhance photolysis of various chemicals in the aqueous system with dissolved organic matter (DOM) as sensitizer. The excitation of chromophores on the DOM molecule further generates reactive species as triplet states DOM, singlet oxygen, hydroxyl radical, carbonate radical etc. We investigated the photosensitization properties of Beaufort Fulvic Acid, Suwannee River Fulvic Acid, South Platte River Fulvic Acid, and Jeddah wastewater treatment plant effluent organic matter with a sunlight simulator. DOM photochemical properties were characterized by observing their performances in 3DOM*, singlet oxygen, hydroxyl radical production with indirect probing protocols. Sensitized degradation of 0.1 μM and 0.02 μM 2, 4, 6- Trimethylphenol exhibited higher pseudo-first-order rate constant than that of 10 μM. Pre-irradiated DOMs were found to be depressed in photochemical properties. Photolysis of 5 different contaminants: ibuprofen, bisphenol A, acetaminophen, cimetidine, and caffeine were found to be enhanced in the presence of sensitizers. The possible reaction pathways were revealed. Long time irradiance induced change in contaminants degradation kinetics in some DOM solutions, which was proposed to be due to the irradiation initiated indirect transformation of DOMs. Key Words: Photolysis Dissolved Organic Matter, Triplet State DOM, Singlet Oxygen, Hydroxyl Radical, Contaminants Degradation.

  9. A Nanosystem Capable of Releasing a Photosensitizer Bioprecursor under Two‐Photon Irradiation for Photodynamic Therapy

    Science.gov (United States)

    Wu, Hao; Zeng, Fang; Zhang, Hang; Xu, Jiangsheng

    2015-01-01

    The applications of photodynamic therapy (PDT) are usually limited by photosensitizers' side effects and singlet oxygen's short half‐life. Herein, a mitochondria‐targeted nanosystem is demonstrated to enhance the PDT efficacy by releasing a bio‐precursor of photosensitizer under two‐photon irradiation. A phototriggerable coumarin derivative is first synthesized by linking 5‐aminolevulinic acid (5‐ALA, the bio‐precursor) to coumarin; and the nanosystem (CD‐ALA‐TPP) is then fabricated by covalently incorporating this coumarin derivative and a mitochondria‐targeting compound triphenylphosphonium (TPP) onto carbon dots (CDs). Upon cellular internalization, the nanosystem preferentially accumulates in mitochondria; and under one‐ or two‐photon irradiation, it releases 5‐ALA molecules that are then metabolized into protoporphyrin IX in mitochondria through a series of biosynthesis processes. The subsequent red light irradiation induces this endogenously synthesized photosensitizer to generate singlet oxygen, thereby causing oxidant damage to mitochondria and then the apoptosis of the cells. Analysis via 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium bromide (MTT) assays indicate that the novel PDT system exhibits enhanced cytotoxicity toward cancer cells. This study may offer a new strategy for designing PDT systems with high efficacy and low side effects. PMID:27774388

  10. Supersymmetric singlet majorons and cosmology

    International Nuclear Information System (INIS)

    Chun, E.J.; Kim, H.B.; Lukas, A.

    1994-02-01

    We examine cosmological constraints on the lepton number breaking scale in super-symmetric singlet majoron models. Special attention is drawn to the model dependence arising from the particular choice of a certain majoron extension and a cosmological scenario. We find that the bounds on the symmetry breaking scale can vary substantially. Large values of this scale can be allowed if the decoupling temperature of majoron and majorino exceeds the reheating temperature of inflation. In the opposite case an upper bound depending on the majoron model can be obtained which, however, is unlikely to be much larger than 10 10 GeV. (author). 13 refs, 2 figs

  11. In situ electrical and thermal monitoring of printed electronics by two-photon mapping

    DEFF Research Database (Denmark)

    Pastorelli, Francesco; Accanto, Nicolo; Jørgensen, Mikkel

    2017-01-01

    Printed electronics is emerging as a new, large scale and cost effective technology that will be disruptive in fields such as energy harvesting, consumer electronics and medical sensors. The performance of printed electronic devices relies principally on the carrier mobility and molecular packing......-destructive and low-cost testing method is needed. In this study, we demonstrate that nonlinear optical microscopy is a promising technique to achieve this goal. Using ultrashort laser pulses we stimulate two-photon absorption in a roll coated polymer semiconductor and map the resulting two-photon induced...

  12. Arduino Due based tool to facilitate in vivo two-photon excitation microscopy.

    Science.gov (United States)

    Artoni, Pietro; Landi, Silvia; Sato, Sebastian Sulis; Luin, Stefano; Ratto, Gian Michele

    2016-04-01

    Two-photon excitation spectroscopy is a powerful technique for the characterization of the optical properties of genetically encoded and synthetic fluorescent molecules. Excitation spectroscopy requires tuning the wavelength of the Ti:sapphire laser while carefully monitoring the delivered power. To assist laser tuning and the control of delivered power, we developed an Arduino Due based tool for the automatic acquisition of high quality spectra. This tool is portable, fast, affordable and precise. It allowed studying the impact of scattering and of blood absorption on two-photon excitation light. In this way, we determined the wavelength-dependent deformation of excitation spectra occurring in deep tissues in vivo.

  13. Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

    Science.gov (United States)

    Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

    1988-01-01

    Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

  14. Two-photon indirect transitions in crossed electric and magnetic fields

    International Nuclear Information System (INIS)

    Hassan, A.R.

    1980-05-01

    A semiclassical theory of the effect of a crossed electric, E, and magnetic, H, fields in the phonon-assisted one- and two-photon transitions is presented. The approach we follow treats the electric field as a small perturbation in the presence of a magnetic field. The behaviour is essentially of magnetic field type. The effect of the electric field is to reduce the indirect gap, the Landau levels spacing and to destroy the Landau selection rules. One- and two-photon absorption coefficients have the same energetic behaviour. A numerical application to GaP gives the limiting value of E/H valid in this approach. (author)

  15. Search for a Higgs Boson Decaying into Two Photons at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

    2002-01-01

    A Higgs particle produced in association with a Z boson and decaying into two photons is searched for in the data collected by the L3 experiment at LEP. All possible decay modes of the Z boson are investigated. No signal is observed in 447.5 pb^-1 of data recorded at centre-of-mass energies up to 209 GeV. Limits on the branching fraction of the Higgs boson decay into two photons as a function of the Higgs mass are derived. A lower limit on the mass of a fermiophobic Higgs boson is set at 105.4 GeV at 95% confidence level.

  16. Axial range of conjugate adaptive optics in two-photon microscopy.

    Science.gov (United States)

    Paudel, Hari P; Taranto, John; Mertz, Jerome; Bifano, Thomas

    2015-08-10

    We describe an adaptive optics technique for two-photon microscopy in which the deformable mirror used for aberration compensation is positioned in a plane conjugate to the plane of the aberration. We demonstrate in a proof-of-principle experiment that this technique yields a large field of view advantage in comparison to standard pupil-conjugate adaptive optics. Further, we show that the extended field of view in conjugate AO is maintained over a relatively large axial translation of the deformable mirror with respect to the conjugate plane. We conclude with a discussion of limitations and prospects for the conjugate AO technique in two-photon biological microscopy.

  17. Insights into esophagus tissue architecture using two-photon confocal microscopy

    Science.gov (United States)

    Liu, Nenrong; Wang, Yue; Feng, Shangyuan; Chen, Rong

    2013-08-01

    In this paper, microstructures of human esophageal mucosa were evaluated using the two-photon laser scanning confocal microscopy (TPLSCM), based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). The distribution of epithelial cells, muscle fibers of muscularis mucosae has been distinctly obtained. Furthermore, esophageal submucosa characteristics with cancer cells invading into were detected. The variation of collagen, elastin and cancer cells is very relevant to the pathology in esophagus, especially early esophageal cancer. Our experimental results indicate that the MPM technique has the much more advantages for label-free imaging, and has the potential application in vivo in the clinical diagnosis and monitoring of early esophageal cancer.

  18. Model studies on the photosensitized isomerization of bixin.

    Science.gov (United States)

    Montenegro, Mariana A; Rios, Alessandro de O; Mercadante, Adriana Z; Nazareno, Mónica A; Borsarelli, Claudio D

    2004-01-28

    The photosensitized isomerization reaction of the natural cis carotenoid bixin (methyl hydrogen 9'-cis-6, 6'-diapocarotene-6, 6'-dioate) with rose bengal or methylene blue as the sensitizer in acetonitrile/methanol (1:1) solution was studied using UV-vis spectroscopy, high-performance liquid chromatography (HPLC), and time-resolved spectroscopic techniques, such as laser-flash photolysis and singlet oxygen phosphorescence detection. In both N(2)- and air-saturated solutions, the main product formed was all-trans-bixin. The observed isomerization rate constants, k(obs), decreased in the presence of air or with increase in the bixin concentration, suggesting the participation of the excited triplet state of bixin, (3)Bix, as precursor of the cis--> trans process. On the other hand, bixin solutions in the absence of sensitizer and/or light did not degrade, indicating that the ground state of bixin is stable to thermal isomerization at room temperature. Time-resolved spectroscopic experiments confirmed the formation of the excited triplet state of bixin and its deactivation by ground state bixin and molecular oxygen quenching processes. The primary isomerization products only degraded in the presence of air and under prolonged illumination conditions, probably due to the formation of oxidation products by reaction with singlet molecular oxygen. An energy-transfer mechanism was used to explain the observed results for the bixin transformations, and the consequences for food color are discussed.

  19. Cholesterol photosensitized oxidation in food and biological systems.

    Science.gov (United States)

    Cardenia, Vladimiro; Rodriguez-Estrada, Maria Teresa; Boselli, Emanuele; Lercker, Giovanni

    2013-03-01

    Lipid oxidation is one of the main chemical degradations occurring in biological systems and leads to the formation of compounds that are related to aging and various chronic and degenerative diseases. The extent of oxidation will depend on the presence of antioxidants/pro-oxidants, the unsaturation degree of fatty acids, and environmental conditions. Lipid oxidation can also affect other molecules that have double bonds in their chemical structures, such as cholesterol. Cholesterol oxidation products (COPs) have been studied in depth, because of their negative and controversial biological effects. The formation of COPs can be particularly favored in the presence of light and photosensitizers, since they generate excited singlet oxygen that rapidly reacts with the double bond by a non radical mechanism and without any induction period. The present review intends to provide an overall and critical picture of cholesterol photosensitized oxidation in food and biological systems, and its possible impact on human health and well-being. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  20. Radiation carcinogenesis: radioprotectors and photosensitizers

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1982-01-01

    This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer

  1. Radiation carcinogenesis: radioprotectors and photosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Fry, R.J.M.

    1982-01-01

    This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer.

  2. New cubic perovskites for one- and two-photon water splitting using the computational materials repository

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Landis, David; Thygesen, Kristian Sommer

    2012-01-01

    screening of around 19 000 oxides, oxynitrides, oxysulfides, oxyfluorides, and oxyfluoronitrides in the cubic perovskite structure with PEC applications in mind. We address three main applications: light absorbers for one- and two-photon water splitting and high-stability transparent shields to protect...

  3. Saturated two-photon absorption by atoms in a perturber gas

    NARCIS (Netherlands)

    Nienhuis, G.

    We derive a general expression for the two-photon absorption spectrum of a state-atom excited by two monochromatic radiation fields. Collisional line-brodening effects are incorporated, and the result allows inclusion of profiles with a validity outside the impact limit. Results of previous work are

  4. A study of Two Photon Decays of Charmonium Resonances Formed in Proton Anti-Proton Annihilations

    Energy Technology Data Exchange (ETDEWEB)

    Pedlar, Todd Kristofer [Northwestern Univ., Evanston, IL (United States)

    1999-06-01

    In this dissertation we describe the results of an investigation of the production of charmonium states (ηc, η'c, χ0 and χ2) in Fermilab experiment E835 via antiproton-proton annihilation and their detection via their decay into two photons.

  5. Gold Core Mesoporous Organosilica Shell Degradable Nanoparticles for Two-Photon Imaging and Gemcitabine Monophosphate Delivery

    KAUST Repository

    Rhamani, Saher

    2017-09-12

    The synthesis of gold core degradable mesoporous organosilica shell nanoparticles is described. The nanopaticles were very efficient for two-photon luminescence imaging of cancer cells and for in vitro gemcitabine monophosphate delivery, allowing promising theranostic applications in the nanomedicine field.

  6. Phosphorus ligand imaging with two-photon fluorescence spectroscopy: towards rational catalyst immobilization

    NARCIS (Netherlands)

    Marras, F.; Kluwer, A.M.; Siekierzycka, J.R.; Vozza, A.; Brouwer, A.M.; Reek, J.N.H.

    2010-01-01

    Spotless catalysts: Ligand immobilization was studied by two-photon fluorescence microscopy with a fluorescent nixantphos ligand as probe (see picture). In the immobilization process ligand aggregates form in solution and are deposited on the support, where they appear as bright spots in

  7. Nanostructured diode for infrared photodetection through nondegenerate two-photon absorption

    Science.gov (United States)

    Fix, Baptiste; Jaeck, Julien; Vest, Benjamin; Verdun, Michaël; Beaudoin, Grégoire; Sagnes, Isabelle; Pelouard, Jean-Luc; Haïdar, Riad

    2017-07-01

    We investigate infrared detection at room temperature using non-degenerate two-photon absorption in a nanostructured indium phosphide photodiode. We designed the detector structure to achieve a good nonlinear absorption by combining three major ideas: first, we use the non-degenerate two-photon absorption process, which is known to be more efficient than the previously used degenerate two-photon absorption. Second, we ensured a correct spatial overlap of our pump field with our signal field. Third, we optimized the nanostructuration to increase the signal field amplitude locally within the active medium of the device. The resulting device consists of a PIN junction embedded between a back-reflecting gold mirror and a top grating. We experimentally characterized our diode with regard to reflectivity and two-photon absorption generated photocurrent for a continuous-wave pump and a nanosecond pulsed signal of around 3.39 μm. Owing to the nanostructuration, the generated photocurrent shows a gain of 24 with respect to the bulk response of InP.

  8. Plasmonic control of nonlinear two-photon absorption in graphene nanocomposites

    International Nuclear Information System (INIS)

    Cox, Joel D; Singh, Mahi R; Antón, Miguel A; Carreño, Fernando

    2013-01-01

    Nonlinear two-photon absorption in a quantum dot–graphene nanoflake nanocomposite system has been investigated. An external laser field is applied to the nanocomposite to simultaneously observe two-photon processes in the quantum dot and excite localized surface plasmons in the graphene nanodisk. This resonance condition can be achieved by tuning the plasmon resonance frequency in the graphene nanoflake via electrostatic gating. It is found that the strong local field of the graphene plasmons can enhance and control nonlinear optical processes in the quantum dot. Specifically, we show that the two-photon absorption coefficient in the quantum dot can be switched between single- and double-peaked spectra by modifying the graphene–quantum dot separation. Two-photon processes in the quantum dot can also be switched on or off by slightly changing the gate voltage applied to the graphene. Our findings indicate that this system can be used for nonlinear optical applications such as all-optical switching, biosensing and signal processing. (paper)

  9. Dipole model for double meson production in two-photon interactions at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, V.P. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Caixa Postal 354, Pelotas, RS (Brazil); Machado, M.V.T. [Universidade Federal do Pampa, Centro de Ciencias Exatas e Tecnologicas, Campus de Bage, Bage, RS (Brazil)

    2007-02-15

    In this work double vector meson production in two-photon interactions at high energies is investigated considering saturation physics. We extend the color dipole picture for this process and study the energy and virtuality dependence of the forward differential cross section. A comparison with previous results is presented, and the contribution of the different photon polarizations is estimated. (orig.)

  10. Search for a Higgs boson decaying into two photons in the CMS ...

    Indian Academy of Sciences (India)

    Keywords. CMS; Large Hadron Collider; low-mass Higgs; photons; electromagnetic calorimeter. Abstract. A search for a Higgs boson decaying into two photons in collisions at the LHC at a centre-of-mass energy of 7 TeV is presented. The analysis is performed on a dataset corresponding to 1.66 fb-1 of data recorded in ...

  11. Novel approach for studying two-photon transitions in heavy HCI

    Science.gov (United States)

    Trotsenko, S.; Kumar, A.; Banaś, D.; Volotka, A. V.; Gumberidze, A.; Kozhuharov, C.; Thorn, D. B.; Beyer, H. F.; Fritzsche, S.; Hagmann, S.; Hess, S.; Jagodziński, P.; Reuschl, R.; Salem, S.; Simon, A.; Spillmann, U.; Trassinelli, M.; Tribedi, L. C.; Weber, G.; Winters, D.; Stöhlker, T.

    2012-11-01

    In this contribution, we report on an experimental approach which allowed for a background-free measurements of the two-photon spectral shape. A number of advantages over conventional techniques lead to the ability for the first time to experimentally disentangle relativistic and non-relativistic theories with an excellent agreement to the first one.

  12. Two-photon finite-pulse model for resonant transitions in attosecond experiments

    Science.gov (United States)

    Jiménez-Galán, Álvaro; Martín, Fernando; Argenti, Luca

    2016-02-01

    We present an analytical model capable of describing two-photon ionization of atoms with attosecond pulses in the presence of intermediate and final isolated autoionizing states. The model is based on the finite-pulse formulation of second-order time-dependent perturbation theory. It approximates the intermediate and final states with Fano's theory for resonant continua, and it depends on a small set of atomic parameters that can either be obtained from separate ab initio calculations or be extracted from a few selected experiments. We use the model to compute the two-photon resonant photoelectron spectrum of helium below the N =2 threshold for the RABITT (reconstruction of attosecond beating by interference of two-photon transitions) pump-probe scheme, in which an XUV attosecond pulse train is used in association with a weak IR probe, obtaining results in quantitative agreement with those from accurate ab initio simulations. In particular, we show that (i) the use of finite pulses results in a homogeneous redshift of the RABITT beating frequency, as well as a resonant modulation of the beating frequency in proximity to intermediate autoionizing states; (ii) the phase of resonant two-photon amplitudes generally experiences a continuous excursion as a function of the intermediate detuning, with either zero or 2 π overall variation.

  13. GPC light shaper for speckle-free one- and two-photon contiguous pattern excitation

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Palima, Darwin; Villangca, Mark Jayson

    2014-01-01

    Generalized Phase Contrast (GPC) is an efficient method for generating speckle-free contiguous optical distributions useful in diverse applications such as static beam shaping, optical manipulation and recently, for excitation in two-photon optogenetics. To fully utilize typical Gaussian lasers...

  14. Measurement Induced Enhancement of Squeezing in Nondegenerate Two-Photon Jaynes-Cummings Model

    International Nuclear Information System (INIS)

    Ye Saiyun

    2006-01-01

    Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement.

  15. Polarizable Embedded RI-CC2 Method for Two-Photon Absorption Calculations

    DEFF Research Database (Denmark)

    Hršak, Dalibor; Khah, Alireza Marefat; Christiansen, Ove

    2015-01-01

    We present a novel polarizable embedded resolution-of-identity coupled cluster singles and approximate doubles (PERI-CC2) method for calculation of two-photon absorption (TPA) spectra of large molecular systems. The method was benchmarked for three types of systems: a water-solvated molecule...

  16. Plasmonic control of nonlinear two-photon absorption in graphene nanocomposites.

    Science.gov (United States)

    Cox, Joel D; Singh, Mahi R; Antón, Miguel A; Carreño, Fernando

    2013-09-25

    Nonlinear two-photon absorption in a quantum dot-graphene nanoflake nanocomposite system has been investigated. An external laser field is applied to the nanocomposite to simultaneously observe two-photon processes in the quantum dot and excite localized surface plasmons in the graphene nanodisk. This resonance condition can be achieved by tuning the plasmon resonance frequency in the graphene nanoflake via electrostatic gating. It is found that the strong local field of the graphene plasmons can enhance and control nonlinear optical processes in the quantum dot. Specifically, we show that the two-photon absorption coefficient in the quantum dot can be switched between single- and double-peaked spectra by modifying the graphene-quantum dot separation. Two-photon processes in the quantum dot can also be switched on or off by slightly changing the gate voltage applied to the graphene. Our findings indicate that this system can be used for nonlinear optical applications such as all-optical switching, biosensing and signal processing.

  17. Higgs decay into two photons from a 3HDM with flavor symmetry

    International Nuclear Information System (INIS)

    Aranda, Alfredo; Bonilla, Cesar; Anda, Francisco de; Delgado, Antonio; Hernández-Sánchez, Jaime

    2013-01-01

    In this short Letter we show that the excess of events in the decay of Higgs to two photons reported by ATLAS and CMS can be easily accommodated in a flavor renormalizable three Higgs doublet model (3HDM). The model is consistent with all fermion masses, mixing angles, and flavor changing neutral current constraints

  18. Direct creation of excitonic molecules by two-photon absorption in quantum wells

    International Nuclear Information System (INIS)

    Hassan, A.R.

    1992-09-01

    A theory of the direct creation of excitonic molecule (biexciton) by direct two-photon absorption in semiconductor quantum well structures is developed. Analytical expression of the biexciton two-photon absorption coefficient is given for both photon polarizations. Excitonic-interband-two-photon and exciton one-photon processes in Quantum Wells (QW) have also been investigated. The analytical forms and numerical values of the momentum matrix elements involved in each process are provided. The biexciton matrix element has been calculated adopting a six-parameter variational wave function. A numerical estimation for GaAs QW shows that the biexciton two photon absorption (BTPA) process dominates the other processes by different orders of magnitude. This enhancement essentially comes from the resonance effect and the structure of the matrix elements included in each process. Furthermore, the (BTPA) process in QW for both polarizations is enhanced over its bulk value by about 4 and 5 orders of magnitude respectively. This increase is interpreted as due to the spatial confinement of the QW. (author). 16 refs, 4 tabs

  19. Picosecond phase conjugation in two-photon absorption in poly-di-acetylenes

    International Nuclear Information System (INIS)

    Nunzi, Dominique Jean-Michel

    1990-01-01

    Poly-di-acetylenes exhibit a large two-photon absorption at 1064 nm wavelength. Its different effects on phase-conjugate nonlinearity are described in the framework of picosecond experiments. In solutions, gels, and films (optically thin media), third-order susceptibility appears as an increasing intensity dependent function. Phase measurements by nonlinear interferometry with the substrate or with the solvent are compared with predictions of a resonantly driven three level system. Phase-conjugate response exhibits a multi-exponential decay. Polarization symmetries analysis shows a one-dimensional effect. Study under strong static electric field action reveals that we face charged species bound to photoconductive polymer chains. In PTS single crystals (optically thick media), response saturates and cancels at high light intensity. This is well accounted for by propagation equations solved in large two-photon absorption conditions. The effect is exploited in a phase conjugation experiment under external optical pump excitation. We thus demonstrate that enhanced nonlinearity is a two-photon absorption relayed and amplified by mid-gap absorbing species which have been created by this two-photon absorption. We formally face a four-photon absorption described by a positive imaginary seventh-order non-linearity. (author) [fr

  20. Real-time tracking mitochondrial dynamic remodeling with two-photon phosphorescent iridium (III) complexes.

    Science.gov (United States)

    Huang, Huaiyi; Yang, Liang; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Diao, JiaJie; Liu, Jiankang; Ji, Liangnian; Long, Jiangang; Chao, Hui

    2016-03-01

    Mitochondrial fission and fusion control the shape, size, number, and function of mitochondria in the cells of organisms from yeast to mammals. The disruption of mitochondrial fission and fusion is involved in severe human diseases such as Parkinson's disease, Alzheimer's disease, metabolic diseases, and cancers. Agents that can real-time track the mitochondrial dynamics are of great importance. However, the short excitation wavelengths and rapidly photo-bleaching properties of commercial mitochondrial dyes render them unsuitable for tracking mitochondrial dynamics. Thus, mitochondrial targeting agents that exhibit superior photo-stability under continual light irradiation, deep tissue penetration and at intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds employ low-energy near-infrared light and have emerged as a non-invasive tool for real-time cell imaging. Here, cyclometalated Ir(III) complexes (Ir1-Ir5) are demonstrated as one- and two-photon phosphorescent probes for the real-time imaging and tracking of mitochondrial fission and fusion. The results indicate that Ir2 is well suited for two-photon phosphorescent tracking of mitochondrial fission and fusion in living cells and in Caenorhabditis elegans (C. elegans). This study provides a practical use for mitochondrial targeting two-photon phosphorescent Ir(III) complexes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Coherent control of two photon fluorescence with a high-resolution spectral phase shaper

    NARCIS (Netherlands)

    Postma, S.; Corkum, Paul; Jonas, David M.; Offerhaus, Herman L.; Subramaniam, Vinod; Miller, R.J.Dwayne; van Hulst, N.F.; Weiner, Andrew M.

    2006-01-01

    We present effects of spectral shaping on the two-photon fluorescence from fluorescent dye molecules in solution and from quantum dots. The experiments are done with sub-25 fs pulses around 800 nm and a compact (7×10 cm2) high resolution reflective spectral phase shaper. Our results demonstrate that

  2. Stability and bandgaps of layered perovskites for one- and two-photon water splitting

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; García Lastra, Juan Maria; Hüser, Falco

    2013-01-01

    in the Ruddlesden–Popper phase of the layered perovskite structure. Based on screening criteria for the stability, bandgaps and band edge positions, we suggest 20 new materials for the light harvesting photo-electrode of a one-photon water splitting device and 5 anode materials for a two-photon device with silicon...

  3. Atomic Dipole Squeezing in the Correlated Two-Mode Two-Photon Jaynes-Cummings Model

    Science.gov (United States)

    Dong, Zhengchao; Zhao, Yonglin

    1996-01-01

    In this paper, we study the atomic dipole squeezing in the correlated two-mode two-photon JC model with the field initially in the correlated two-mode SU(1,1) coherent state. The effects of detuning, field intensity and number difference between the two field modes are investigated through numerical calculation.

  4. Search for a Higgs boson decaying into two photons in the CMS ...

    Indian Academy of Sciences (India)

    2012-11-15

    Nov 15, 2012 ... Limits are set on the cross-section of a Standard Model Higgs boson decaying into two photons, and on the cross-section ... of these two methods, the probability to find Higgs boson vertices within 10 mm of their ... so-called R9 variable, that describes the compactness of the energy deposition in the. ECAL ...

  5. Phosphorescent probes for two-photon microscopy of oxygen (Conference Presentation)

    Science.gov (United States)

    Vinogradov, Sergei A.; Esipova, Tatiana V.

    2016-03-01

    The ability to quantify oxygen in vivo in 3D with high spatial and temporal resolution is much needed in many areas of biological research. Our laboratory has been developing the phosphorescence quenching technique for biological oximetry - an optical method that possesses intrinsic microscopic capability. In the past we have developed dendritically protected oxygen probes for quantitative imaging of oxygen in tissue. More recently we expanded our design on special two-photon enhanced phosphorescent probes. These molecules brought about first demonstrations of the two-photon phosphorescence lifetime microscopy (2PLM) of oxygen in vivo, providing new information for neouroscience and stem cell biology. However, current two-photon oxygen probes suffer from a number of limitations, such as sub-optimal brightness and high cost of synthesis, which dramatically reduce imaging performance and limit usability of the method. In this paper we discuss principles of 2PLM and address the interplay between the probe chemistry, photophysics and spatial and temporal imaging resolution. We then present a new approach to brightly phosphorescent chromophores with internally enhanced two-photon absorption cross-sections, which pave a way to a new generation of 2PLM probes.

  6. Fabrication of 3D nano/microelectrodes via two-photon-polymerization

    DEFF Research Database (Denmark)

    Abaddi, Mohammed Al-; Sasso, Luigi; Dimaki, Maria

    2012-01-01

    The integration of two-photon polymerization technology with standard microfabrication techniques is imperative for the use of this tool in micro- and nanotechnology and especially for the future commercialization of the technology. In this work, we report a novel method for the fabrication of 3D...

  7. Quantum properties of counterpropagating two-photon states generated in a planar waveguide

    Czech Academy of Sciences Publication Activity Database

    Peřina ml., Jan

    2008-01-01

    Roč. 77, č. 1 (2008), 013803/1-013803/14 ISSN 1050-2947 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : quantum properties * two-photon states Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.908, year: 2008

  8. Simultaneous and consecutive two-photon excited fluorescence detection in conventional-size liquid chromatography.

    NARCIS (Netherlands)

    Gooijer, C.; Brinkman, U.A.T.; Velthorst, N.H.; van de Nesse, R.J.; van der Wegen, R.J.

    1995-01-01

    The applicability of two-photon excitation (TPE) for fluorescence detection in flow dynamic systems was explored. Emphasis was on conventional-size liquid chromatography (LC) and a direct comparison was made with one-photon excitation (OPE) by the use of standard laser- and lamp excitation.

  9. A mechanistic study on the phototoxicity of atorvastatin: singlet oxygen generation by a phenanthrene-like photoproduct.

    Science.gov (United States)

    Montanaro, Sara; Lhiaubet-Vallet, Virginie; Iesce, MariaRosaria Iesce; Previtera, Lucio; Miranda, Miguel Angel

    2009-01-01

    Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have been reported and associated with photosensitivity disorders. Previous work dealing with ATV photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative. Laser flash photolysis of ATV, at both 266 and 308 nm, led to a transient spectrum with two maxima at lambda= 360 and lambda= 580 nm (tau= 41 micro), which was assigned to the primary intermediate of the stilbene-like photocyclization. On the basis of the absence of a triplet-triplet absorption, the role of the parent drug as singlet oxygen photosensitizer can be discarded. By contrast, a stable phenanthrene-like photoproduct would be a good candidate to play this role. Laser flash photolysis of this compound showed a triplet-triplet transient absorption at lambdamax = 460 nm with a lifetime of 26 micro, which was efficiently quenched by oxygen (kq = 3 (+/-0.2) x 10(9) M(-1) s(-1)). Its potential to photosensitize formation of singlet oxygen was confirmed by spin trapping experiments, through conversion of TEMP to the stable free radical TEMPO. The photoreactivity of the phenanthrene-like photoproduct was investigated using Trp as a marker. The disappearance of the amino acid fluorescence (lambdamax = 340 nm) after increasing irradiation times at 355 nm was taken as a measurement of photodynamic oxidation. To confirm the involvement of a type II mechanism, the same experiment was also performed in D2O; this resulted in a significant enhancement of the reaction rate. On the basis of the obtained photophysical and photochemical results, the phototoxicity of atorvastatin can be attributed to singlet oxygen formation with the phenanthrene-like photoproduct as a photosensitizer.

  10. Two-photon photoacoustics ultrasound measurement by a loss modulation technique

    Science.gov (United States)

    Lai, Yu-Hung; Chang, Chieh-Feng; Cheng, Yu-Hsiang; Sun, Chi-Kuang

    2013-03-01

    In this work, we investigated the principle of the two-photon absorption (TPA) detection with a loss modulation technique, and first demonstrated the existence of two-photon photoacoustics ultrasound excited by a femtosecond high repetition rate laser. By using the AO modulation with different modulation frequencies, we successfully create the beating of the light signal when the two arms of the beams are both spatial and temporal overlapping. The pulse train of the femtosecond laser causes the narrow band excitation, providing the frequency selectivity and sensitivity. Moreover, the pulse energy is no more than 15nJ/pulse, which is at least 3 orders of magnitude smaller than that of the nanosecond laser, and therefore prevents the thermal damage of the sample. With the help of lock-in detection and a low noise amplifier, we can separate the signal of two-photon absorption from one-photon absorption. We used an ultrasonic transducer to detect the response of the sample, and verified the existence of the two-photon photoacoustics ultrasound generating by the femtosecond laser. Several contrast agents, such as the black carbon solution, the fluorescence dye and the nano-particles, were used in the experiment. In the end, we demonstrated the application, two photo-acoustic imaging, which provides the high spatial resolution (<10μm) and large penetration depth (~1mm), to the simulated biological tissue. This is a milestone to develop the two-photon photoacoustics microscopy, which, in principle, has the great potential to achieve the in vitro and in vivo high resolution deep tissue imaging.

  11. Sensing for intracellular thiols by water-insoluble two-photon fluorescent probe incorporating nanogel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xudong; Zhang, Xin; Wang, Shuangqing; Li, Shayu [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Hu, Rui, E-mail: hurui@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Yi, E-mail: yili@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Guoqiang, E-mail: gqyang@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-04-15

    Highlights: • A novel “turn-on” two-photon fluorescent probe based on a π-conjugated triarylboron luminogen was designed and synthesized. • Fast, selective and sensitive detection of biothiols in 100% aqueous solution by simply loaded on a nanogel. • Single-photon and two-photon fluorescent bioimaging of biothiols in NIH/3T3 fibroblasts. - Abstract: A novel “turn-on” two-photon fluorescent probe containing a π-conjugated triarylboron luminogen and a maleimide moiety DMDP-M based on the photo-induced electron transfer (PET) mechanism for biothiol detection was designed and synthesized. By simply loading the hydrophobic DMDP-M on a cross-linked Pluronic{sup ®} F127 nanogel (CL-F127), a probing system DMDP-M/CL-F127 was established, which shows quick response, high selectivity and sensitivity to cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous phase. The DMDP-M/CL-F127 system presented the fastest response to Cys with a rate constant of 0.56 min{sup −1}, and the detection limit to Cys was calculated to be as low as 0.18 μM. The DMDP-M/CL-F127 system has been successfully applied to the fluorescence imaging of biothiols in NIH/3T3 fibroblasts either with single-photon or two-photon excitation because of its high biocompatibility and cell-membrane permeability. The present work provides a general, simple and efficient strategy for the application of hydrophobic molecules to sensing biothiols in aqueous phase, and a novel sensing system for intracellular biothiols fitted for both single-photon and two-photon fluorescence imaging.

  12. Electron Correlations and Two-Photon States in Polycyclic Aromatic Hydrocarbon Molecules: A Peculiar Role of Geometry

    OpenAIRE

    Aryanpour, K.; Shukla, A.; Mazumdar, S.

    2013-01-01

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene and circumcoronene, all possessing $D_{6h}$ point group symmetry versus ovalene with $D_{2h}$ symmetry, within the Pariser-Parr-Pople model of interacting $\\pi$-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitat...

  13. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yanyan; Zhang Peng [Department of Chemistry, New Mexico Tech, Socorro, NM 87801 (United States); Rogelj, Snezna, E-mail: pzhang@nmt.edu [Department of Biology, New Mexico Tech, Socorro, NM 87801 (United States)

    2010-02-10

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO{sub 2}-NH{sub 2}-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO{sub 2}-NH{sub 2}-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  14. Dopamine-quantum dot conjugate: a new kind of photosensitizers for photodynamic therapy of cancers

    Energy Technology Data Exchange (ETDEWEB)

    Chou Kailiang; Meng He; Cen Yan; Li Lei; Chen Jiyao, E-mail: jychen@fudan.edu.cn [Fudan University, State Key Laboratory of Surface Physics and Department of Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) (China)

    2013-01-15

    The thiol-capped CdTe quantum dots (QDs) with the average size of 3.5 nm were linked to dopamines (DAs) forming DA-QD conjugates, with the characteristics of red-shifted photoluminescence (PL) peak and remarkably reduced PL lifetime. The QDs in the conjugates readily accept the electron from DAs when excited by the visible light, resulting in the oxidation of DAs and the production of singlet oxygen ({sup 1}O{sub 2}) with the yield comparable to that of sulfonated aluminum phthalocyanine (AlPcS), a popularly used photosensitizer. The DA-QD conjugate can quickly penetrate into human nasopharyngeal carcinoma (KB) cells and seriously destroy cells under the irradiation of visible lights, showing the potential to become a new kind of photosensitizers.

  15. A series of fluorene-based two-photon absorbing molecules: synthesis, linear and nonlinear characterization, and bioimaging

    Science.gov (United States)

    Andrade, Carolina D.; Yanez, Ciceron O.; Rodriguez, Luis; Belfield, Kevin D.

    2010-01-01

    The synthesis, structural, and photophysical characterization of a series of new fluorescent donor–acceptor and acceptor-acceptor molecules, based on the fluorenyl ring system, with two-photon absorbing properties is described. These new compounds exhibited large Stokes shifts, high fluorescent quantum yields, and, significantly, high two-photon absorption cross sections, making them well suited for two-photon fluorescence microscopy (2PFM) imaging. Confocal and two-photon fluorescence microscopy imaging of COS-7 and HCT 116 cells incubated with probe I showed endosomal selectivity, demonstrating the potential of this class of fluorescent probes in multiphoton fluorescence microscopy. PMID:20481596

  16. A spirobifluorene-based two-photon fluorescence probe for mercury ions and its applications in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn; Zhang, Yanzhen; Zhang, Wu; Li, Shaozhi; Tan, Jingjing; Han, Zhongying

    2017-05-01

    A novel spirobifluorene derivative SPF-TMS, which containing dithioacetal groups and triphenylamine units, was synthesized. The probing behaviors toward various metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TMS exhibits high sensitivity and selectivity for mercury ions. The detection limit was at least 8.6 × 10{sup −8}M, which is excellent comparing with other optical sensors for Hg{sup 2+}. When measured by two-photon excited fluorescence technique in THF at 800 nm, the two-photon cross-section of SPF-TMS is 272 GM. Especially, upon reaction with mercury species, SPF-TMS yielded another two-photon dye SPF-DA. Both SPF-TMS and SPF-DA emit strong two-photon induced fluorescence and can be applied in cell imaging by two-photon microscopy. - Highlights: • We report a spirobifluorene-based molecule as two-photon fluorescent probe with large two-photon cross-section. • The molecule has exclusive selectivity and sensitivity for mercury species. • The molecule has large two-photon emission changes before and after addition of Hg{sup 2+}. • Both the probe and the mercury ion-promoted reaction product can be applied in cell imaging by two-photon microscopy.

  17. Colour singlets in perturbative QCD

    International Nuclear Information System (INIS)

    Bassetto, A.

    1979-01-01

    In the axial gauge and at the leading log level, a definite and consistent picture seems to emerge of a parton decay into states in which many partons are found just before confinement should take place. They are grouped into colourless clusters in a number sufficient to exhaust the ''final'' state, still possessing a finite average mass. This result is peculiar of QCD, in particular of its non-abelian nature. Large transverse momenta or more generally average invariant quantities of partons are mainly due to the multiplicities involved in the branching processes. If eventually confinement would convert these clusters into hadrons (and this is of course the main issue which has still to be proven) without a large rearrangement of the colour lines, the picture we have found for colour singlets could apply to the real hadronic world. (author)

  18. Zethrenes, Extended p -Quinodimethanes, and Periacenes with a Singlet Biradical Ground State

    KAUST Repository

    Sun, Zhe

    2014-08-19

    ConspectusResearchers have studied polycyclic aromatic hydrocarbons (PAHs) for more than 100 years, and most PAHs in the neutral state reported so far have a closed-shell electronic configuration in the ground state. However, recent studies have revealed that specific types of polycyclic hydrocarbons (PHs) could have a singlet biradical ground state and exhibit unique electronic, optical, and magnetic activities. With the appropriate stabilization, these new compounds could prove useful as molecular materials for organic electronics, nonlinear optics, organic spintronics, organic photovoltaics, and energy storage devices. However, before researchers can use these materials to design new devices, they need better methods to synthesize these molecules and a better understanding of the fundamental relationship between the structure and biradical character of these compounds and their physical properties. Their biradical character makes these compounds difficult to synthesize. These compounds are also challenging to physically characterize and require the use of various experimental techniques and theoretic methods to comprehensively describe their unique properties.In this Account, we will discuss the chemistry and physics of three types of PHs with a significant singlet biradical character, primarily developed in our group. These structures are zethrenes, Z-shaped quinoidal hydrocarbons; hydrocarbons that include a proaromatic extended p-quinodimethane unit; and periacenes, acenes fused in a peri-Arrangement. We used a variety of synthetic methods to prepare these compounds and stabilized them using both thermodynamic and kinetic approaches. We probed their ground-state structures by electronic absorption, NMR, ESR, SQUID, Raman spectroscopy, and X-ray crystallography and also performed density functional theory calculations. We investigated the physical properties of these PHs using various experimental methods such as one-photon absorption, two-photon absorption

  19. Singlet and triplet instability theorems

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Tomonori; Hirata, So, E-mail: sohirata@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2015-09-21

    A useful definition of orbital degeneracy—form-degeneracy—is introduced, which is distinct from the usual energy-degeneracy: Two canonical spatial orbitals are form-degenerate when the energy expectation value in the restricted Hartree–Fock (RHF) wave function is unaltered upon a two-electron excitation from one of these orbitals to the other. Form-degenerate orbitals tend to have isomorphic electron densities and occur in the highest-occupied and lowest-unoccupied molecular orbitals (HOMOs and LUMOs) of strongly correlated systems. Here, we present a mathematical proof of the existence of a triplet instability in a real or complex RHF wave function of a finite system in the space of real or complex unrestricted Hartree–Fock wave functions when HOMO and LUMO are energy- or form-degenerate. We also show that a singlet instability always exists in a real RHF wave function of a finite system in the space of complex RHF wave functions, when HOMO and LUMO are form-degenerate, but have nonidentical electron densities, or are energy-degenerate. These theorems provide Hartree–Fock-theory-based explanations of Hund’s rule, a singlet instability in Jahn–Teller systems, biradicaloid electronic structures, and a triplet instability during some covalent bond breaking. They also suggest (but not guarantee) the spontaneous formation of a spin density wave (SDW) in a metallic solid. The stability theory underlying these theorems extended to a continuous orbital-energy spectrum proves the existence of an oscillating (nonspiral) SDW instability in one- and three-dimensional homogeneous electron gases, but only at low densities or for strong interactions.

  20. Prospects of radical-interacting porphyrin photosensitizers and their possible use in photodynamic therapy

    Science.gov (United States)

    Gal, Dezso; Shuliakovskaya, T.; Vidoczy, Tamas; Elzemzam, Saleh; Vasvari, Gabor; Suemegi, L.; Kuti, Zsolt

    1994-03-01

    Based on literature data obtained in various fields with respect to studies on the role of free radicals in biology and on the kinetics of triplet-doublet interactions, it is suggested that excited photosensitizers react in vivo with free radicals formed in malignant tissues during photodynamic therapy (PDT) and this interaction competes with sensitizer-radical + molecule and the singlet oxygen mediated effects. Experimental results by laser flash photolysis and electron spin resonance revealed that sensitizer applied in PDT react with stable free radicals presumably both by energy transfer and electron transfer.

  1. Stability of bisphenol A (BPA) in oil-in water emulsions under riboflavin photosensitization.

    Science.gov (United States)

    Jang, Eun Yeong; Park, Chan Uk; Kim, Mi-Ja; Lee, JaeHwan

    2012-08-01

    Effects of riboflavin photosensitization on the degradation of bisphenol A (BPA) were determined in oil-in-water (O/W) emulsions containing ethylenediaminetetraacetic acid (EDTA) or sodium azide, which are a metal chelator or a singlet oxygen quencher, respectively. Also, the distribution of BPA between the continuous and dispersed phases in O/W emulsions was analyzed by high-performance liquid chromatography (HPLC). The concentration of BPA in O/W emulsions significantly decreased by 38.6% after 2 h under visible light irradiation and in the presence of riboflavin (P riboflavin photosensitization (P riboflavin photodegradation in O/W emulsions. Concentration of BPA, an endocrine disrupting chemical, was decreased significantly in oil-in-water emulsions under riboflavin and visible light irradiation. BPA in continuous aqueous phase was major target of riboflavin photosensitization. However, BPA was distributed more densely in lipid phase and more protected from riboflavin photosensitized O/W emulsions. This study can help to decrease the level of BPA in foods made of O/W emulsions containing riboflavin, which could be displayed under visible light irradiation. © 2012 Institute of Food Technologists®

  2. A Closer Look at Dark Toxicity of the Photosensitizer TMPyP in Bacteria.

    Science.gov (United States)

    Eckl, Daniel B; Dengler, Linda; Nemmert, Marina; Eichner, Anja; Bäumler, Wolfgang; Huber, Harald

    2018-01-01

    Photodynamic inactivation of bacteria (PIB) is based on photosensitizers which absorb light and generate reactive oxygen species (ROS), killing cells via oxidation. PIB is evaluated by comparing viability with and without irradiation, where reduction of viability in the presence of the photosensitizer without irradiation is considered as dark toxicity. This effect is controversially discussed for photosensitizers like TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluensulfonate). TMPyP shows a high absorption coefficient for blue light and a high yield of ROS production, especially singlet oxygen. Escherichia coli and Bacillus atrophaeus were incubated with TMPyP and irradiated with different light sources at low radiant exposures (μW per cm²), reflecting laboratory conditions of dark toxicity evaluation. Inactivation of E. coli occurs for blue light, while no effect was detectable for wavelengths >450 nm. Being more susceptible toward PIB, growth of B. atrophaeus is even reduced for light with emission >450 nm. Decreasing the light intensities to nW per cm² for B. atrophaeus, application of TMPyP still caused bacterial killing. Toxic effects of TMPyP disappeared after addition of histidine, quenching residual ROS. Our experiments demonstrate that the evaluation of dark toxicity of a powerful photosensitizer like TMPyP requires low light intensities and if necessary additional application of substances quenching any residual ROS. © 2017 The American Society of Photobiology.

  3. Singlet Oxygen-Mediated Oxidation during UVA Radiation Alters the Dynamic of Genomic DNA Replication.

    Directory of Open Access Journals (Sweden)

    Dany Graindorge

    Full Text Available UVA radiation (320-400 nm is a major environmental agent that can exert its deleterious action on living organisms through absorption of the UVA photons by endogenous or exogenous photosensitizers. This leads to the production of reactive oxygen species (ROS, such as singlet oxygen (1O2 and hydrogen peroxide (H2O2, which in turn can modify reversibly or irreversibly biomolecules, such as lipids, proteins and nucleic acids. We have previously reported that UVA-induced ROS strongly inhibit DNA replication in a dose-dependent manner, but independently of the cell cycle checkpoints activation. Here, we report that the production of 1O2 by UVA radiation leads to a transient inhibition of replication fork velocity, a transient decrease in the dNTP pool, a quickly reversible GSH-dependent oxidation of the RRM1 subunit of ribonucleotide reductase and sustained inhibition of origin firing. The time of recovery post irradiation for each of these events can last from few minutes (reduction of oxidized RRM1 to several hours (replication fork velocity and origin firing. The quenching of 1O2 by sodium azide prevents the delay of DNA replication, the decrease in the dNTP pool and the oxidation of RRM1, while inhibition of Chk1 does not prevent the inhibition of origin firing. Although the molecular mechanism remains elusive, our data demonstrate that the dynamic of replication is altered by UVA photosensitization of vitamins via the production of singlet oxygen.

  4. Diagnostics of MCF plasmas using Lyman-α fluorescence excited by one or two photons

    International Nuclear Information System (INIS)

    Voslamber, D.

    1998-11-01

    Laser-induced Lyman-α fluorescence of the hydrogen isotopes is investigated with regard to diagnostic applications in magnetically confined fusion plasmas. A formal analysis is presented for two excitation schemes: one-photon and Doppler-free two-photon excitation. The analysis includes estimates of the expected experimental errors arising from the photon noise and from the sensitivity of the observed fluorescence signals to variations of the plasma and laser parameters. Both excitation schemes are suitable primarily for application in the plasma edge, but even in the plasma bulk of large machines they can still be applied in combination with a diagnostic neutral beam. The two-photon excitation scheme is particularly attractive because it involves absorption spectra that are resolved within the Doppler width. This implies a large diagnostic potential and in particular offers a way to measure the deuterium-tritium fuel mix in fusion reactors. (author)

  5. Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Song, Minsoo; Yoon, Tai Hyun [Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

    2013-02-15

    We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s{sup 2} {sup 1}S{sub 0}{r_reversible} 6s7s {sup 1}S{sub 0}) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm{sup 3} and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s{sup 1}S{sub 0} state via the intercombination 6s6p{sup 3}P{sub 1} state with a high signal-to-noise ratio even at the temperature of 340 Degree-Sign C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.

  6. Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

    International Nuclear Information System (INIS)

    Song, Minsoo; Yoon, Tai Hyun

    2013-01-01

    We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s 2 1 S 0 ↔ 6s7s 1 S 0 ) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm 3 and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s 1 S 0 state via the intercombination 6s6p 3 P 1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.

  7. Rotational temperature measurement of NO gas using two-photon excitation spectrum

    Science.gov (United States)

    Ozaki, Tadao; Matsui, Yoshihiko; Ohsawa, Toshihiko

    1981-04-01

    The rotational temperature of nitric oxide gas has been measured by means of a single-beam two-photon excitation spectrum method using a pulsed continuously tunable dye laser. The nitric oxide gas was enclosed at about 40 Torr in a quartz cell which was put in an electric oven. The NO γ (0-0) band and R11+Q21 branches were used to obtain the two-photon excitation spectrum. The rotational temperatures were determined using the fact that molecules are distributed in the rotational levels according to the Boltzmann law. The temperature range was from room temperature to about 470 K. Observed temperatures were in good agreement with cell temperatures which were obtained by using a thermocouple.

  8. Influence of two-photon absorption on soliton self-frequency shift

    DEFF Research Database (Denmark)

    Steffensen, Henrik; Agger, Christian; Bang, Ole

    2012-01-01

    In this paper we develop an analytical model for the soliton self-frequency shift, which includes second- and thirdorder dispersion, self-steepening, the full Raman term, and, for the first time to our best knowledge, the effect of two-photon absorption (TPA). We show that TPA can have a signific......In this paper we develop an analytical model for the soliton self-frequency shift, which includes second- and thirdorder dispersion, self-steepening, the full Raman term, and, for the first time to our best knowledge, the effect of two-photon absorption (TPA). We show that TPA can have...... a significant effect on soliton dynamics in soft-glass materials such as chalcogenides, by severely depleting a soliton and thereby limiting the achievable redshift. Based on the model, we derive a nonlinear loss length after which the redshift is effectively halted by TPA, which proves to be a useful design...

  9. Higgs boson decay into two photons in an electromagnetic background field

    DEFF Research Database (Denmark)

    Nielsen, N. K.

    2014-01-01

    The amplitude for Higgs boson decay into two photons in a homogeneous and time-independent magnetic field is investigated by proper-time regularization in a gauge-invariant manner and is found to be singular at large field values. The singularity is caused by the component of the charged vector b...... boson field that is tachyonic in a strong magnetic field. Also, tools for the computation of the amplitude in a more general electromagnetic background are developed.......The amplitude for Higgs boson decay into two photons in a homogeneous and time-independent magnetic field is investigated by proper-time regularization in a gauge-invariant manner and is found to be singular at large field values. The singularity is caused by the component of the charged vector...

  10. Two-photon photodissociation dynamics of state-selected NO2

    Science.gov (United States)

    Bigio, Laurence; Grant, Edward R.

    1987-07-01

    Quantum states of NO2 are selected and then photodissociated by resonant two-photon photoexcitation. The details of the photolysis and the optical-UV double-resonance (OUDR) spectroscopy are discussed, and results are presented for: (1) observations of the product state selected two-photon photodissociation cross section of NO2 near the O(1D) threshold, (2) the dynamics of NO production as a function of features selected in the photodissociation spectrum, (3) N labeling of relevant features by OUDR spectroscopy, and (4) estimation of the O(1D)/O(3P) branching ratio. A qualitative connection is established between the present observations and a new theoretical approach developed by Balint-Kurti et al. (1985) to account specifically for electronic degrees of freedom in state-to-state photodissociation.

  11. Two-photon-induced x-ray emission in neon atoms

    International Nuclear Information System (INIS)

    Sun Yuping; Wang Chuankui; Rinkevicius, Zilvinas; Gel'mukhanov, Faris; Carniato, Stephane; Simon, Marc; Taieeb, Richard

    2010-01-01

    We investigated the resonant x-ray emission from a neon atom induced by the two-photon population of a double-core-hole excited state. Two qualitatively different schemes of this process are studied: The first one involves an off-resonant intermediate single-core-hole state; the second scheme passes through a resonant core-ionized intermediate state. The numerical simulations of the resonant x-ray emission performed for different peak intensities and pulse durations show significant population of the double-core-hole final states. Therefore, rather strong two-photon absorption-induced x-ray emission is predicted for both studied schemes. Thus, high counting rates in experimental measurements are expected.

  12. Two-Photon or Higher-Order Absorbing Optical Materials for Generation of Reactive Species

    Science.gov (United States)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R. (Inventor); Perry, Joseph W. (Inventor)

    2013-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  13. Ultrabright narrow-band telecom two-photon source for long-distance quantum communication

    Science.gov (United States)

    Niizeki, Kazuya; Ikeda, Kohei; Zheng, Mingyang; Xie, Xiuping; Okamura, Kotaro; Takei, Nobuyuki; Namekata, Naoto; Inoue, Shuichiro; Kosaka, Hideo; Horikiri, Tomoyuki

    2018-04-01

    We demonstrate an ultrabright narrow-band two-photon source at the 1.5 µm telecom wavelength for long-distance quantum communication. By utilizing a bow-tie cavity, we obtain a cavity enhancement factor of 4.06 × 104. Our measurement of the second-order correlation function G (2)(τ) reveals that the linewidth of 2.4 MHz has been hitherto unachieved in the 1.5 µm telecom band. This two-photon source is useful for obtaining a high absorption probability close to unity by quantum memories set inside quantum repeater nodes. Furthermore, to the best of our knowledge, the observed spectral brightness of 3.94 × 105 pairs/(s·MHz·mW) is also the highest reported over all wavelengths.

  14. Intravital two-photon imaging of adoptively transferred B lymphocytes in inguinal lymph nodes.

    Science.gov (United States)

    Park, Chung; Hwang, Il-Young; Kehrl, John H

    2009-01-01

    Intravital two-photon imaging allows the observation of immune cells in intact organs of live animals in real time. Recently, several studies using two-photon microscopy have detailed the motility of mouse B and T lymphocyte within lymph nodes and have shown a dependence upon chemokine receptor signaling for the basal velocity of the cells. For, example, T cells from Gnia2 (-/-)mice, deficient in the heterotrimer G-protein G alpha subunit G(alpha i2) have markedly impaired chemokine-triggered chemotaxis. In vivo these cells have reduced motility and impaired positioning within lymph nodes. Gnia2 (-/-) B cells exhibit similar defects. In addition, B cells from Rgs1 (-/-) mice, deficient in a major negative regulator of G(alpha i), have a more robust motility than do wild-type B cells. Here, we describe procedures for visualizing the behavior of fluorescently labeled and adoptively transferred B lymphocytes within the inguinal lymph node of live mice.

  15. Polarization-resolved two-photon luminescence microscopy of V-groove arrays

    DEFF Research Database (Denmark)

    Beermann, J.; Novikov, S. M.; Holmgaard, T.

    2012-01-01

    Using two-photon luminescence (TPL) microscopy and local reflection spectroscopy we investigate electromagnetic field enhancement effects from a mu m-sized composition of 450-nm-deep V-grooves milled by focused ion beam in a thick gold film and assembled to feature, within the same structure, ind...... obtained to evaluation of local field enhancements using TPL microscopy, especially when investigating extended structures exhibiting different radiation channels, are discussed. (C)2011 Optical Society of America......Using two-photon luminescence (TPL) microscopy and local reflection spectroscopy we investigate electromagnetic field enhancement effects from a mu m-sized composition of 450-nm-deep V-grooves milled by focused ion beam in a thick gold film and assembled to feature, within the same structure...

  16. Multiplexed two-photon microscopy of dynamic biological samples with shaped broadband pulses.

    Science.gov (United States)

    Pillai, Rajesh S; Boudoux, Caroline; Labroille, Guillaume; Olivier, Nicolas; Veilleux, Israel; Farge, Emmanuel; Joffre, Manuel; Beaurepaire, Emmanuel

    2009-07-20

    Coherent control can be used to selectively enhance or cancel concurrent multiphoton processes, and has been suggested as a means to achieve nonlinear microscopy of multiple signals. Here we report multiplexed two-photon imaging in vivo with fast pixel rates and micrometer resolution. We control broadband laser pulses with a shaping scheme combining diffraction on an optically-addressed spatial light modulator and a scanning mirror allowing to switch between programmable shapes at kiloHertz rates. Using coherent control of the two-photon excited fluorescence, it was possible to perform selective microscopy of GFP and endogenous fluorescence in developing Drosophila embryos. This study establishes that broadband pulse shaping is a viable means for achieving multiplexed nonlinear imaging of biological tissues.

  17. Mitochondrial Dynamics Tracking with Two-Photon Phosphorescent Terpyridyl Iridium(III) Complexes

    Science.gov (United States)

    Huang, Huaiyi; Zhang, Pingyu; Qiu, Kangqiang; Huang, Juanjuan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2016-01-01

    Mitochondrial dynamics, including fission and fusion, control the morphology and function of mitochondria, and disruption of mitochondrial dynamics leads to Parkinson’s disease, Alzheimer’s disease, metabolic diseases, and cancers. Currently, many types of commercial mitochondria probes are available, but high excitation energy and low photo-stability render them unsuitable for tracking mitochondrial dynamics in living cells. Therefore, mitochondrial targeting agents that exhibit superior anti-photo-bleaching ability, deep tissue penetration and intrinsically high three-dimensional resolutions are urgently needed. Two-photon-excited compounds that use low-energy near-infrared excitation lasers have emerged as non-invasive tools for cell imaging. In this work, terpyridyl cyclometalated Ir(III) complexes (Ir1-Ir3) are demonstrated as one- and two-photon phosphorescent probes for real-time imaging and tracking of mitochondrial morphology changes in living cells. PMID:26864567

  18. [Frontiers in Live Bone Imaging Researches. Two-Photon Excitation Microscopy, principles and technologies].

    Science.gov (United States)

    Oikawa, Yoshiro

    2015-06-01

    The "two photon absorption" phenomenon had been predicted by the American Physicist, Maria Ghöppert-Mayer in 1931. Denk and Webb group had proved it in 1990 and the first product had been launched in the market in 1996. But ever since the product became available, the number of users are not increased. Moreover, the system had been too difficult to use and the system sometimes stay not working in labs. But recently, the new easier-to-use products are released and the ultra short pulse IR laser became stable. And its applications are extending from neuro-science to oncology or immunology fields. Due to these reasons, the shipment of multi-photon microscope in Japan in 2013 is approximately 40 units which is 3 times bigger than in 2010. In this paper, I would like to discuss the principles of two-photon microscopy and some of the new technologies for the higher signal capture efficiency.

  19. Two-photon spectroscopy study of edge absorption peculiarities in oxygen-octahedric ferroelectrics

    International Nuclear Information System (INIS)

    Shablaev, S.I.; Danishevskij, A.M.; Subashiev, V.K.

    1984-01-01

    Two-photon absorption (TPA) spectra of ferroelectric crystals with BaTiO 3 , KTaO 3 and SrTiO 3 perovskite strUcture Were obtained. The detailed investigation of temperature dependence of edge spectrum regions was conducted and on the basis of their analysis the indirect character of edge absorption was concluded for all mentioned crystals. TPA spectra of BaTiO 3 and KTaO 3 are characterized by the regions corresponding to one indirect edge TPA spectra of SrTiO 3 - to two indirect edges. The corresponding inter-zone gaps were determined for all investigated crystals, the energy of phonons, participating in indirect two photon transitions, inter-zone gaps, corresponding to direct transitions were determined as well

  20. Tagging system for scattered electrons in two-photon reactions at the MD-1 detector

    International Nuclear Information System (INIS)

    Aul'chenko, V.M.; Baru, S.E.; Blinov, A.E.

    1994-01-01

    The Tagging System of the MD-1 detector at the VEPP-4 collider used for studying of two-photon reactions is described. A transverse magnetic field enables one to detect scattered electrons and positrons even at zero scattering angles. The system energy resolution for scattered electron is 1.75% at the beam energy 4.7 GeV. 32 refs.; 21 figs.; 1 tabs

  1. Measurement of the radiative width of the A2(1320) in two-photon interactions

    International Nuclear Information System (INIS)

    Althoff, M.; Braunschweig, W.; Gerhards, R.; Kirschfink, F.J.; Martyn, H.U.; Rosskamp, P.; Wallraff, W.; Hilger, E.; Kracht, T.; Krasemann, H.L.; Krueger, J.; Lohrmann, E.; Poelz, G.; Poesnecker, K.U.; Bowler, M.G.; Bull, P.; Cashmore, R.J.; Dauncey, P.; Devenish, R.; Heath, G.; Mellor, D.; Ratoff, P.; Baranko, G.; Caldwell, A.; Cherney, M.; Izen, J.M.; Ritz, S.; Strom, D.; Takashima, M.; Wicklund, E.; Wu Saulan; Zonering, G.

    1986-01-01

    The reaction e + e - ->e + e - A 2 (1320) has been observed by detecting the decay A 2 ->π + π - π 0 . The two-photon width of the A 2 has been measured to be GAMMA(A 2 ->γγ)=(0.90+-0.27(stat)+-0.16(syst)) keV. The cross section sigma(γγ->π + π - π 0 ) has been determined outside the A 2 resonance region. (orig.)

  2. Probing QCD dynamics in two-photon interactions at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, V P [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, Pelotas, RS (Brazil); Machado, M V T [Centro de Ciencias Exatas e Tecnologicas, Universidade Federal do Pampa, Campus de Bage, Rua Carlos Barbosa. CEP 96400-970. Bage, RS (Brazil); Sauter, W K [High Energy Physics Phenomenology Group, GFPAE IF-UFRGS, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil)

    2007-07-15

    In this paper, the two-photon interactions at high energies are investigated considering different approaches for the QCD dynamics. In particular, we calculate the {gamma}*{gamma}* total cross section in different theoretical approaches and present a comparison among the predictions of the BFKL dynamics at leading and next-to-leading order with those from saturation physics. We analyse the possibility that the future linear colliders could discriminate between these different approaches.

  3. Spectral distribution of the 2S → 1S two-photon transition in atoms ...

    Indian Academy of Sciences (India)

    Two-photon decay process was discussed first by Göppert-Mayer [1,2] in the 1930s for hydrogen and later it was described in detail for hydrogen and helium using non- relativistic approach by Breit and Teller [3]. The 2S state decays to ground state primarily by the emission of two electric-dipole photons, i.e. E1E1 or 2E1.

  4. Unambiguous modification of nonorthogonal single- and two-photon polarization states

    International Nuclear Information System (INIS)

    Torres-Ruiz, F. A.; Aguirre, J.; Delgado, A.; Lima, G.; Neves, L.; Roa, L.; Saavedra, C.; Padua, S.

    2009-01-01

    In this paper we propose a probabilistic method which allows an unambiguous modification of two nonorthogonal quantum states. We experimentally implement this protocol by using two-photon polarization states generated in the process of spontaneous parametric down conversion. In the experiment, for codifying initial quantum states, we consider single-photon states and heralded detection. We show that the application of this protocol to entangled states allows a fine control of the amount of entanglement of the initial state.

  5. Two-photon absorption in mesoionic compounds pumped at the visible and at the infrared

    CERN Document Server

    Rakov, N; Da Rocha, G B; Simas, A M; Athayde-Filho, P A F; Miller, J

    2000-01-01

    Intensity dependent transmission and laser-induced fluorescence were observed in liquid solutions of mesoionic compounds (MIC) pumped with nanosecond lasers operating at 1064, 604, and 570 nm. The results indicate that two-photon absorption (TPA) is the dominant mechanism which causes the observed behavior. The TPA cross-sections measured have values from 0.33*10/sup -20/ cm/sup 4//GW to 0.43*10/sup -18/ cm /sup 4//GW. (20 refs).

  6. Two Photon Decays of Charmonium States Produced in Proton - Anti-proton Annihilations

    Energy Technology Data Exchange (ETDEWEB)

    Fast, James Elliot [UC, Irvine

    1992-01-01

    The two photon decays of the $\\eta_c$ and $\\chi_2$ charmonium states have been measured in $p\\bar{p}$ annihilation using the E760 apparatus at Fermilab during the 1990-1991 fixed target run. A search for the $\\eta^\\prime_c$ resonance decaying into two photons has also been conducted. The processes $p\\bar{p} \\to R \\to \\gamma \\gamma$ have been measured using a cooled beam of antiprotons circulating in the Fermilab accumulator ring intersecting an internal hydrogen gas-jet target. The final state photons were measured with a high granularity, high resolution lead glass calorimeter. From a scan of the $\\eta_c$ resonance region, the mass, the total width, and the branching ratio to two photons have been measured. The results are $M_{\\eta_c}$ = 2989.9 ± 2.2 ±0.4 MeV/$c^2$, $\\Gamma_{\\eta_c}$ = 15.6±6.9±6.4 MeV, and $BR({\\eta_c} \\to \\gamma \\gamma)$ = (2.77 ± 1.19 ± 0.43) x $10^{-4}$. Data were taken at the peak of the $X_2$ resonance, and the two photon branching ratio was determined to be $BR(X_2 \\to \\gamma \\gamma)$ = (1.54 ± 0.40 ± 0.24) x $10^{-4}$. Data were collected at several energies around the expected mass of the $\\eta^\\prime_c$. Upper limits have been placed on the product of branching ratios, $BR(\\eta^\\prime_c \\to p\\bar{p})BR(\\eta^\\prime_c \\to \\gamma \\gamma)$, as function of the $\\eta^\\prime_c$ mass and total width.

  7. Functionalized 3D Architected Materials via Thiol-Michael Addition and Two-Photon Lithography.

    Science.gov (United States)

    Yee, Daryl W; Schulz, Michael D; Grubbs, Robert H; Greer, Julia R

    2017-04-01

    Fabrication of functionalized 3D architected materials is achieved by a facile method using functionalized acrylates synthesized via thiol-Michael addition, which are then polymerized using two-photon lithography. A wide variety of functional groups can be attached, from Boc-protected amines to fluoroalkanes. Modification of surface wetting properties and conjugation with fluorescent tags are demonstrated to highlight the potential applications of this technique. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Dynamics of multilevel molecules and pulse propagation beyond rotating wave approximation near two-photon resonance

    International Nuclear Information System (INIS)

    Liu Jicai; Wang Chuankui; Gel'mukhanov, Faris

    2007-01-01

    Dynamics of multilevel molecules and pulse propagation is studied near the two-photon resonance. We have found a strict solution of this problem beyond the rotating wave approximation. Our analytical solution is in close agreement with the strict numerical solution for the 4,4 ' -bis(dimethylamino) stilbene molecule. The compensation of the dynamical Stark shift is studied for fixed-in-space molecules. It is shown that the orientational disorder does not allow complete compensation of the dynamical Stark shift

  9. Rapid Prototyping of Chemical Microsensors Based on Molecularly Imprinted Polymers Synthesized by Two-Photon Stereolithography.

    Science.gov (United States)

    Gomez, Laura Piedad Chia; Spangenberg, Arnaud; Ton, Xuan-Anh; Fuchs, Yannick; Bokeloh, Frank; Malval, Jean-Pierre; Tse Sum Bui, Bernadette; Thuau, Damien; Ayela, Cédric; Haupt, Karsten; Soppera, Olivier

    2016-07-01

    Two-photon stereolithography is used for rapid prototyping of submicrometre molecularly imprinted polymer-based 3D structures. The structures are evaluated as chemical sensing elements and their specific recognition properties for target molecules are confirmed. The 3D design capability is exploited and highlighted through the fabrication of an all-organic molecularly imprinted polymeric microelectromechanical sensor. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Evidence for the Direct Two-Photon Transition from psi to J/psi

    NARCIS (Netherlands)

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ferroli, R. B.; Ban, Y.; Becker, J.; Berger, N.; Bertani, M. B.; Bian, J. M.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, X.; Calcaterra, A. C.; Cao, G. F.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, Y.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; Ding, W. M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Fava, L.; Feldbauer, F.; Feng, C. Q.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y. P.; Han, Y. L.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, B.; Huang, G. M.; Huang, J. S.; Huang, X. T.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, X. B.; Ji, X. L.; Jia, L. K.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Kuehn, W.; Lai, W.; Lange, J. S.; Leung, J. K. C.; Li, C. H.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, K.; Li, Lei; Li, N. B.; Li, Q. J.; Li, S. L.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Liu, B. J.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, C. Y.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H.; Liu, H. B.; Liu, H. H.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, Kun; Liu, Kai; Liu, K. Y.; Liu, P. L.; Liu, S. B.; Liu, X.; Liu, X. H.; Liu, Y. B.; Liu, Y.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. Y.; Ma, Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, H.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Morales, C. Morales; Motzko, C.; Muchnoi, N. Yu; Nefedov, Y.; Nicholson, C.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S. P.; Park, J. W.; Pelizaeus, M.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Prencipe, E.; Pun, C. S. J.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schulze, J.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, X. Y.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. D.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Thorndike, E. H.; Tian, H. L.; Toth, D.; Ulrich, M. U.; Varner, G. S.; Wang, B.; Wang, B. Q.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q.; Wang, Q. J.; Wang, S. G.; Wang, X. F.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Weidenkaff, P.; Wen, Q. G.; Wen, S. P.; Werner, M. W.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, S. X.; Wu, W.; Wu, Z.; Xia, L. G.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, G. M.; Xu, H.; Xu, Q. J.; Xu, X. P.; Xu, Y.; Xu, Z. R.; Xue, F.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, T.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yu, S. P.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Zafar, A. A.; Zallo, A. Z.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. G.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, L.; Zhang, S. H.; Zhang, T. R.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. S.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, H. S.; Zhao, J. W.; Zhao, K. X.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zheng, Z. P.; Zhong, B.; Zhong, J.; Zhou, L.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, X. W.; Zhu, Y. M.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.; Zuo, J. X.

    2012-01-01

    The two-photon transition psi(3686) -> gamma gamma J/psi is studied in a sample of 1.06 x 10(8) psi(3686) decays collected by the BESIII detector. The branching fraction is measured to be (3.1 +/- 0.6(stat)(-1.0)(+0.8)(syst)) x 10(-4) using J/psi -> e(+)e(-) and J/psi -> mu(+)mu(-) decays, and its

  11. Fs-transient absorption and fluorescence upconversion after two- photon excitation of carotenoids in solution and in LHC II

    CERN Document Server

    Wall, P J; Fleming, G R

    2000-01-01

    With time resolved two-photon techniques we determined the lifetime and two-photon spectrum of the forbidden S/sub 1/ state of beta - carotene (9+or-0.2 ps), lutein (15+or-0.5 ps) and the energy transferring carotenoids in LHC II (250+or-50 fs). (7 refs).

  12. Two photon spectroscopy of rubidium atoms in a magneto-optic trap

    International Nuclear Information System (INIS)

    Fretel, E.

    1997-01-01

    Two photon transitions without doppler effect can be used as an atomic reference. The aim of this work is to study two photon transitions of rubidium atoms in a magneto-optical trap. The chosen transition is from the level 5 2 S 1/2 toward the level 5 2 D 5/2 . The magneto-optical trap is achieved by using 3 pairs of perpendicular laser beams and by setting a magnetic field gradient. About 10 18 atoms are trapped and cooled in a 1 mm 3 volume. In a first stage we have realized an optical double resonance experiment from the level 5 2 S 1/2 toward the level 5 2 D 5/2 by populating the intermediate level 5 2 P 3/2 . Then we have studied the two photon transition in this cluster of cold atoms. A particular setting of the experiment allows to reduce the effect of ray broadening and shifting due to the magnetic field of the trap

  13. Diagnosis of basal cell carcinoma by two photon excited fluorescence combined with lifetime imaging

    Science.gov (United States)

    Fan, Shunping; Peng, Xiao; Liu, Lixin; Liu, Shaoxiong; Lu, Yuan; Qu, Junle

    2014-02-01

    Basal cell carcinoma (BCC) is the most common type of human skin cancer. The traditional diagnostic procedure of BCC is histological examination with haematoxylin and eosin staining of the tissue biopsy. In order to reduce complexity of the diagnosis procedure, a number of noninvasive optical methods have been applied in skin examination, for example, multiphoton tomography (MPT) and fluorescence lifetime imaging microscopy (FLIM). In this study, we explored two-photon optical tomography of human skin specimens using two-photon excited autofluorescence imaging and FLIM. There are a number of naturally endogenous fluorophores in skin sample, such as keratin, melanin, collagen, elastin, flavin and porphyrin. Confocal microscopy was used to obtain structures of the sample. Properties of epidermic and cancer cells were characterized by fluorescence emission spectra, as well as fluorescence lifetime imaging. Our results show that two-photon autofluorescence lifetime imaging can provide accurate optical biopsies with subcellular resolution and is potentially a quantitative optical diagnostic method in skin cancer diagnosis.

  14. Two-photon anisotropy: Analytical description and molecular modeling for symmetrical and asymmetrical organic dyes

    International Nuclear Information System (INIS)

    Fu Jie; Przhonska, Olga V.; Padilha, Lazaro A.; Hagan, David J.; Van Stryland, Eric W.; Belfield, Kevin D.; Bondar, Mikhail V.; Slominsky, Yuriy L.; Kachkovski, Alexei D.

    2006-01-01

    One- and two-photon anisotropy spectra of a series of symmetrical and asymmetrical polymethine (PD) and fluorene molecules were measured experimentally and discussed theoretically within the framework of three-state and four-state models. For all the molecules discussed in this paper, the experimental two-photon anisotropy values, r 2PA , lie in the relatively narrow range from 0.47 to 0.57 and remain almost independent of wavelength over at least two electronic transitions. This is in contrast with their one-photon anisotropy, which shows strong wavelength dependence, typically varying from ∼0 to 0.38 over the same transitions. A detailed analysis of the two-photon absorption (2PA) processes allows us to conclude that a three-state model can explain the 2PA anisotropy spectra of most asymmetrical PDs and fluorenes. However, this model is inadequate for all the symmetrical molecules. Experimental values of r 2PA for symmetrical polymethines and fluorenes can be explained by symmetry breaking leading to the deviation of the orientation of the participating transition dipole moments from their 'classical' orientations

  15. An integrated single- and two-photon non-diffracting light-sheet microscope

    Science.gov (United States)

    Lau, Sze Cheung; Chiu, Hoi Chun; Zhao, Luwei; Zhao, Teng; Loy, M. M. T.; Du, Shengwang

    2018-04-01

    We describe a fluorescence optical microscope with both single-photon and two-photon non-diffracting light-sheet excitations for large volume imaging. With a special design to accommodate two different wavelength ranges (visible: 400-700 nm and near infrared: 800-1200 nm), we combine the line-Bessel sheet (LBS, for single-photon excitation) and the scanning Bessel beam (SBB, for two-photon excitation) light sheet together in a single microscope setup. For a transparent thin sample where the scattering can be ignored, the LBS single-photon excitation is the optimal imaging solution. When the light scattering becomes significant for a deep-cell or deep-tissue imaging, we use SBB light-sheet two-photon excitation with a longer wavelength. We achieved nearly identical lateral/axial resolution of about 350/270 nm for both imagings. This integrated light-sheet microscope may have a wide application for live-cell and live-tissue three-dimensional high-speed imaging.

  16. New developments in two-photon analysis of human skin in vivo

    Science.gov (United States)

    Riemann, I.; Schwarz, M.; Stracke, F.; Ehlers, A.; Dimitrow, E.; Kaatz, M.; König, K.; Le Harzic, R.

    2009-02-01

    Two-photon imaging of human skin using ultra short laser pulses can be used to obtain information about the state of cells and tissues by means of their natural autofluorescence. Using this method, it is possible to determine whether the normal cell pattern is disturbed or the autofluorescence is influenced by internal or external stimuli. Two-photon fluorescence lifetime imaging (FLIM) can further enhance this providing information about physiological processes, fluorophores (like NAD(P)H, collagen, keratin, elastin, flavins, melanin,...) and external applied probes inside cells and tissue parts. For example the part of the cells metabolism and energy level can be determined by analyzing the NADH regarding its free / bound state and its oxidized / reduced state. The combination of two-photon imaging with FLIM may lead to a better understanding and diagnosis of skin reactions and disorders. We also present some results of in vivo simultaneous collagen and elastin measurements in skin dermis. Changes of dermal collagen and elastin content are characteristic for skin aging as well as for pathological skin conditions.

  17. Phonon-Assisted Two-Photon Interference from Remote Quantum Emitters.

    Science.gov (United States)

    Reindl, Marcus; Jöns, Klaus D; Huber, Daniel; Schimpf, Christian; Huo, Yongheng; Zwiller, Val; Rastelli, Armando; Trotta, Rinaldo

    2017-07-12

    Photonic quantum technologies are on the verge of finding applications in everyday life with quantum cryptography and quantum simulators on the horizon. Extensive research has been carried out to identify suitable quantum emitters and single epitaxial quantum dots have emerged as near-optimal sources of bright, on-demand, highly indistinguishable single photons and entangled photon-pairs. In order to build up quantum networks, it is essential to interface remote quantum emitters. However, this is still an outstanding challenge, as the quantum states of dissimilar "artificial atoms" have to be prepared on-demand with high fidelity and the generated photons have to be made indistinguishable in all possible degrees of freedom. Here, we overcome this major obstacle and show an unprecedented two-photon interference (visibility of 51 ± 5%) from remote strain-tunable GaAs quantum dots emitting on-demand photon-pairs. We achieve this result by exploiting for the first time the full potential of a novel phonon-assisted two-photon excitation scheme, which allows for the generation of highly indistinguishable (visibility of 71 ± 9%) entangled photon-pairs (fidelity of 90 ± 2%), enables push-button biexciton state preparation (fidelity of 80 ± 2%) and outperforms conventional resonant two-photon excitation schemes in terms of robustness against environmental decoherence. Our results mark an important milestone for the practical realization of quantum repeaters and complex multiphoton entanglement experiments involving dissimilar artificial atoms.

  18. Supramolecular assembly affording a ratiometric two-photon fluorescent nanoprobe for quantitative detection and bioimaging.

    Science.gov (United States)

    Wang, Peng; Zhang, Cheng; Liu, Hong-Wen; Xiong, Mengyi; Yin, Sheng-Yan; Yang, Yue; Hu, Xiao-Xiao; Yin, Xia; Zhang, Xiao-Bing; Tan, Weihong

    2017-12-01

    Fluorescence quantitative analyses for vital biomolecules are in great demand in biomedical science owing to their unique detection advantages with rapid, sensitive, non-damaging and specific identification. However, available fluorescence strategies for quantitative detection are usually hard to design and achieve. Inspired by supramolecular chemistry, a two-photon-excited fluorescent supramolecular nanoplatform ( TPSNP ) was designed for quantitative analysis with three parts: host molecules (β-CD polymers), a guest fluorophore of sensing probes (Np-Ad) and a guest internal reference (NpRh-Ad). In this strategy, the TPSNP possesses the merits of (i) improved water-solubility and biocompatibility; (ii) increased tissue penetration depth for bioimaging by two-photon excitation; (iii) quantitative and tunable assembly of functional guest molecules to obtain optimized detection conditions; (iv) a common approach to avoid the limitation of complicated design by adjustment of sensing probes; and (v) accurate quantitative analysis by virtue of reference molecules. As a proof-of-concept, we utilized the two-photon fluorescent probe NHS-Ad-based TPSNP-1 to realize accurate quantitative analysis of hydrogen sulfide (H 2 S), with high sensitivity and good selectivity in live cells, deep tissues and ex vivo -dissected organs, suggesting that the TPSNP is an ideal quantitative indicator for clinical samples. What's more, TPSNP will pave the way for designing and preparing advanced supramolecular sensors for biosensing and biomedicine.

  19. Energy and electron transfers in photosensitive chitosan.

    Science.gov (United States)

    Wu, Shuizhu; Zeng, Fang; Zhu, Hongping; Tong, Zhen

    2005-02-23

    Novel photosensitive chitosan was synthesized. The modified chitosan contains photoactive anthracene chromophore moieties. Because of the presence of anthracene chromophores, the polymer absorbs light in the UV-vis spectral region. Electronically excited polymeric chromophores could participate in energy and electron transfer processes to the suitable acceptor molecules. The photosensitive chitosan developed herein could could act as an efficient photosensitizer and lead to the application of the environmentally friendly photocatalytic system for an efficient degradation of a wide range of pollutants.

  20. Fabrication of self-written waveguide in photosensitive polyimide resin by controlling photochemical reaction of photosensitizer

    International Nuclear Information System (INIS)

    Yamashita, K.; Kuro, T.; Oe, K.; Mune, K.; Tagawa, K.; Naitou, R.; Mochizuki, A.

    2004-01-01

    We have investigated optical properties of photosensitive polyimide appropriating for long self-written waveguide fabrication. From systematic measurements of absorption properties, it was found that photochemical reaction of photosensitizer dissolved in the photosensitive polyimide resins relates to transparency after the exposure, which limits the length of the fabricated self-written waveguide. By controlling the photochemical reaction, in which the photosensitive polyimide resin has sufficient transparency during exposure, four times longer self-written waveguide core was fabricated

  1. Effect of oxygen concentration on singlet oxygen luminescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Longchao; Lin, Lisheng; Li, Yirong; Lin, Huiyun; Qiu, Zhihai [MOE Key Laboratory of OptoElectronic Science and Technology for Medicine, Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou 350007 (China); Gu, Ying [Department of Laser Medicine, Chinese PLA General Hospital, Beijing 100853 (China); Li, Buhong, E-mail: bhli@fjnu.edu.cn [MOE Key Laboratory of OptoElectronic Science and Technology for Medicine, Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou 350007 (China)

    2014-08-01

    Singlet oxygen ({sup 1}O{sub 2}) is a major phototoxic component in photodynamic therapy (PDT) and its generation is dependent on the availability of tissue oxygen. To examine the effect of oxygen concentration on {sup 1}O{sub 2} detection, two hydrophilic photosensitizer (PS), rose bengal (RB) and meso-metra (N-methyl-4-pyridyl) porphine tetra tosylate (TMPyP) were used as model PS. Irradiation was carried out using 523 nm under hypoxic (2%, 13%), normoxic (21%) and hyperoxic (65%) conditions. The spectral and spatial resolved {sup 1}O{sub 2} luminescence was measured by near-infrared (NIR) photomultiplier tube (PMT) and camera, respectively. Upon the irradiation, the emission signal mainly consisted of background scattering light, PS fluorescence and phosphorescence, and {sup 1}O{sub 2} luminescence. The PS phosphorescence was evidently dependent on the oxygen concentration and PS type, which resulted in the change of emission profile of {sup 1}O{sub 2} luminescence. This change was further demonstrated on {sup 1}O{sub 2} luminescence image. The present study suggests that the low oxygen concentration could affect {sup 1}O{sub 2} luminescence detection. - Highlights: • Both spectral and spatial resolved {sup 1}O{sub 2} luminescence measurements were performed. • Effect of oxygen concentration on {sup 1}O{sub 2} generation was quantitatively evaluated. • Low oxygen concentration could affect {sup 1}O{sub 2} luminescence detection.

  2. Dibenzoheptazethrene isomers with different biradical characters: An exercise of clar's aromatic sextet rule in singlet biradicaloids

    KAUST Repository

    Sun, Zhe

    2013-12-04

    Clar\\'s aromatic sextet rule has been widely used for the prediction of the reactivity and stability of polycyclic aromatic hydrocarbons with a closed-shell electronic configuration. Recent advances in open-shell biradicaloids have shown that the number of aromatic sextet rings plays an important role in determination of their ground states. In order to test the validity of this rule in singlet biradicaloids, the two soluble and stable dibenzoheptazethrene isomers DBHZ1 and DBHZ2 were prepared by different synthetic approaches and isolated in crystalline form. These two molecules have different numbers of aromatic sextet rings in their respective biradical resonance forms and thus are expected to exhibit varied singlet biradical character. This assumption was verified by different experimental methods, including nuclear magnetic resonance (NMR), electron spin resonance (ESR), superconducting quantum interference device (SQUID), steady-state and transient absorption spectroscopy (TA), and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. DBHZ2, with more aromatic sextet rings in the biradical form, was demonstrated to possess greater biradical character than DBHZ1; as a result, DBHZ2 exhibited an intense one-photon absorption (OPA) in the near-infrared region (λabs max = 804 nm) and a large two-photon absorption (TPA) cross-section (σ(2)max = 2800 GM at 1600 nm). This investigation together with previous studies indicates that Clar\\'s aromatic sextet rule can be further extended to the singlet biradicaloids to predict their ground states and singlet biradical characters. © 2013 American Chemical Society.

  3. In vitro photosensitization initiated by camphorquinone and phenyl propanedione in dental polymeric materials.

    Science.gov (United States)

    Christensen, Terje; Morisbak, Else; Tønnesen, Hanne Hjorth; Bruzell, Ellen M

    2010-09-02

    Documentation is scarce on the photobiological effects of photoinitiators present in dental light curable materials. The aim of this study was to determine cellular effects of the photoinitiators camphorquinone (CQ) and phenyl propanedione (PPD) and to investigate whether these substances produced reactive oxygen species after low and high doses of optical radiation (between 0 and 17J/cm(2)). Rat salivary gland cells in vitro were exposed to visible blue light and/or UVA. Hematoporphyrin (HP), a photosensitizer used in medicine, and the UVA-filter 2-methoxy-4-hydroxy-benzophenone (B-3) were used as reference substances. It was found that PPD produced hydrogen peroxide, but not singlet oxygen, upon light irradiation. CQ produced neither hydrogen peroxide nor singlet oxygen. Cell death by necrosis and apoptosis was induced by irradiation in the presence of CQ, PPD and HP. Doses higher than 6J/cm(2) UVA and blue visible light from a source similar to clinically applied sources, induced apoptosis even in the absence of photosensitizers added. A reciprocity relationship was found between radiant exposure (at constant irradiance) and concentration of photoinitiators. In conclusion, the oral cells under investigation were light sensitive, and the sensitivity increased in presence of photoinitiators. PPD acted by mechanisms that included reactive oxygen species and CQ probably by formation of free radicals. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  4. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    Science.gov (United States)

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-08-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760-1120 nm wavelength range.

  5. Polarization dependence of two-photon transition intensities in rare-earth doped crystals

    Energy Technology Data Exchange (ETDEWEB)

    Le Nguyen, An-Dien [Univ. of California, Berkeley, CA (United States)

    1996-05-01

    A polarization dependence technique has been developed as a tool to investigate phonon scattering (PS), electronic Raman scattering (ERS), and two-photon absorption (TPA) transition intensities in vanadate and phosphate crystals. A general theory for the polarization dependence (PD) of two-photon transition intensities has been given. Expressions for the polarization dependent behavior of two-photon transition intensities have been tabulated for the 32 crystallographic point groups. When the wavefunctions for the initial and final states of a rare-earth doped in crystals are known, explicit PD expressions with no unknown parameters can be obtained. A spectroscopic method for measuring and interpreting phonon and ERS intensities has been developed to study PrVO4, NdVO4, ErVO4, and TmVO4 crystals. Relative phonon intensities with the polarization of the incident and scattered light arbitrarily varied were accurately predicted and subsequently used for alignment and calibration in ERS measurements in these systems for the first time. Since ERS and PS intensities generally follow different polarization curves as a function of polar angles, the two can be uniquely identified by comparing their respective polarization behavior. The most crucial application of the technique in ERS spectroscopy is the establishment of a stringent test for the Axe theory. For the first time, the F1/F2 ratio extracted from the experimental fits of the ERS intensities were compared with those predicted by theories which include both the second- and third-order contributions. Relatively good agreement between the fitted values of F1/F2 and the predicted values using the second-order theory has been found.

  6. Intravital two-photon microscopy of immune cell dynamics in corneal lymphatic vessels.

    Directory of Open Access Journals (Sweden)

    Philipp Steven

    Full Text Available BACKGROUND: The role of lymphatic vessels in tissue and organ transplantation as well as in tumor growth and metastasis has drawn great attention in recent years. METHODOLOGY/PRINCIPAL FINDINGS: We now developed a novel method using non-invasive two-photon microscopy to simultaneously visualize and track specifically stained lymphatic vessels and autofluorescent adjacent tissues such as collagen fibrils, blood vessels and immune cells in the mouse model of corneal neovascularization in vivo. The mouse cornea serves as an ideal tissue for this technique due to its easy accessibility and its inducible and modifiable state of pathological hem- and lymphvascularization. Neovascularization was induced by suture placement in corneas of Balb/C mice. Two weeks after treatment, lymphatic vessels were stained intravital by intrastromal injection of a fluorescently labeled LYVE-1 antibody and the corneas were evaluated in vivo by two-photon microscopy (TPM. Intravital TPM was performed at 710 nm and 826 nm excitation wavelengths to detect immunofluorescence and tissue autofluorescence using a custom made animal holder. Corneas were then harvested, fixed and analyzed by histology. Time lapse imaging demonstrated the first in vivo evidence of immune cell migration into lymphatic vessels and luminal transport of individual cells. Cells immigrated within 1-5.5 min into the vessel lumen. Mean velocities of intrastromal corneal immune cells were around 9 µm/min and therefore comparable to those of T-cells and macrophages in other mucosal surfaces. CONCLUSIONS: To our knowledge we here demonstrate for the first time the intravital real-time transmigration of immune cells into lymphatic vessels. Overall this study demonstrates the valuable use of intravital autofluorescence two-photon microscopy in the model of suture-induced corneal vascularizations to study interactions of immune and subsequently tumor cells with lymphatic vessels under close as possible

  7. Coherent effects on two-photon correlation and directional emission of two two-level atoms

    International Nuclear Information System (INIS)

    Ooi, C. H. Raymond; Kim, Byung-Gyu; Lee, Hai-Woong

    2007-01-01

    Sub- and superradiant dynamics of spontaneously decaying atoms are manifestations of collective many-body systems. We study the internal dynamics and the radiation properties of two atoms in free space. Interesting results are obtained when the atoms are separated by less than half a wavelength of the atomic transition, where the dipole-dipole interaction gives rise to new coherent effects, such as (a) coherence between two intermediate collective states, (b) oscillations in the two-photon correlation G (2) , (c) emission of two photons by one atom, and (d) the loss of directional correlation. We compare the population dynamics during the two-photon emission process with the dynamics of single-photon emission in the cases of a Λ and a V scheme. We compute the temporal correlation and angular correlation of two successively emitted photons using the G (2) for different values of atomic separation. We find antibunching when the atomic separation is a quarter wavelength λ/4. Oscillations in the temporal correlation provide a useful feature for measuring subwavelength atomic separation. Strong directional correlation between two emitted photons is found for atomic separation larger than a wavelength. We also compare the directionality of a photon spontaneously emitted by the two atoms prepared in phased-symmetric and phased-antisymmetric entangled states vertical bar ±> k 0 =e ik 0 ·r 1 vertical bar a 1 ,b 2 >±e ik 0 ·r 2 vertical bar b 1 ,a 2 > by a laser pulse with wave vector k 0 . Photon emission is directionally suppressed along k 0 for the phased-antisymmetric state. The directionality ceases for interatomic distances less than λ/2

  8. Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans.

    Science.gov (United States)

    Fracalossi, Camila; Nagata, Juliana Yuri; Pellosi, Diogo Silva; Terada, Raquel Sano Suga; Hioka, Noboru; Baesso, Mauro Luciano; Sato, Francielle; Rosalen, Pedro Luiz; Caetano, Wilker; Fujimaki, Mitsue

    2016-09-01

    Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Polarised two-photon excitation of quantum well excitons for manipulation of optically pumped terahertz lasers

    Energy Technology Data Exchange (ETDEWEB)

    Slavcheva, G., E-mail: gsk23@bath.ac.uk [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Kavokin, A.V., E-mail: A.Kavokin@soton.ac.uk [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Spin Optics Laboratory, St. Petersburg State University, 1, Ulyanovskaya 198504 (Russian Federation)

    2014-11-15

    Optical pumping of excited exciton states in a semiconductor quantum well embedded in a microcavity is a tool for realisation of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited (2p) and ground (1s) exciton state. We show that the probability of two-photon absorption by a 2p-exciton is strongly dependent on the polarisation of both pumping photons. Five-fold variation of the threshold power for terahertz lasing by switching from circular to co-linear pumping is predicted. We identify photon polarisation configurations for achieving maximum THz photon generation quantum efficiency.

  10. Two Photon Induced Lasing in 1550 nm Quantum Dash Optical Gain Media

    DEFF Research Database (Denmark)

    Capua, Amir; Saal, Abigael; Reithmaier, Johann Peter

    2011-01-01

    We report on a unique lasing mechanism observed in quantum dash Gain media. While the gain media is electrically pumped below lasing threshold, a strong optical pulse excites carriers by two photon absorption into high energy states of the quantum dashes and wetting layer. Fast inter band carrier...... relaxation and capture processes into the ground states of the quantum dashes result in increased gain followed by lasing at the gain peak irrespective of the stimulating pulse wavelength. The temporal response of the lasing line is examined on a 40 GHz scope and full characterization of the pulse...

  11. Multiresonant two-photon-absorption-induced four wave mixing in crystalline rare earth insulators

    International Nuclear Information System (INIS)

    Cone, R.L.; Ender, D.A.; Otteson, M.S.; Fisher, P.L.; Friedman, J.M.; Guggenheim, H.J.

    1982-01-01

    Coherent nonlinear optical generation of omega 4 = omega 1 + omega 2 - omega 3 exhibits strong sharp intermediate (omega 1 ) and two-photon (omega 1 + omega 2 ) resonances in crystalline Tb(OH) 3 and LiTbF 4 , providing a novel method for high resolution coherent measurement of both excited electronic configurations and intermediate 4f/sup n/ states of rare earth ions. New regions of the UV and VUV are thus made accessible to existing tuneable visible and near ultraviolet lasers. Selection of sharp features from broad overlapping absorptions, line narrowing due to phase matching selectivity, and coherent transient applications are discussed

  12. Two-photon collisions at very low Q2 from LEP2. Forthcoming results

    International Nuclear Information System (INIS)

    Almehed, S.; Jarlskog, G.; Mjornmark, U.; Nygren, A.; Zimin, N.; Kapusta, F.; Tyapkin, I.

    1998-01-01

    Experimental results that may soon be obtained in two-photon collisions at very low momentum transfer Q 2 at LEP2 are reviewed. A kinematical range is presented for both the forward and very forward detectors used to measure scattered electrons and positrons. A new acceptance, after this year's upgrade of the beam pipe at the position of the very forward detectors, is evaluated. The corresponding statistics is calculated for an integrated luminosity of 400 pb -1 , that must be collected by the end of LEP2 operation according to current plans

  13. Quantum entropy and polarization measurements of the two-photon system

    Science.gov (United States)

    Alexanian, Moorad; Mkrtchian, Vanik E.

    2018-02-01

    We consider the bipartite state of a two-photon polarization system and obtain the exact analytical expression for the von Neumann entropy in the particular case of a five-parameter polarization density matrix. We investigate and graphically illustrate the dependence of the entropy on these five parameters, in particular, the existence of exotic, transition from exotic to nonexotic, and nonexotic states, where the quantum conditional entropy is negative, both positive and negative, and positive, respectively. We study the "cooling" or "heating" effect that follows from the reduced density of photon 2 when a measurement is performed on photon 1.

  14. A femtosecond Raman generator for long wavelength two-photon and third harmonic generation imaging

    Directory of Open Access Journals (Sweden)

    J. Trägårdh

    2016-12-01

    Full Text Available We demonstrate a femtosecond single pass Raman generator based on an YVO4 crystal pumped by a high energy fiber laser at a wavelength of 1064 nm and a repetition rate of 1 MHz. The Raman generator shifts the pump wavelength to 1175 nm, in a broadband spectrum, making it suitable for multi-photon microscopy. We use the Raman generator for third harmonic generation imaging of live plant specimens as well as for two-photon fluorescence imaging of red fluorescent protein expressing HeLa cells. We demonstrate that the photo-damage to a live specimen is low.

  15. Measurement of the radiative width of the eta'(958) in two-photon interactions

    International Nuclear Information System (INIS)

    Althoff, M.; Braunschweig, W.; Kirschfink, F.J.; Luebelsmeyer, K.; Martyn, H.U.; Rosskamp, P.; Sander, H.G.; Schmitz, D.; Siebke, H.; Wallraff, W.; Fohrmann, R.; Hilger, E.; Kracht, T.; Krasemann, H.L.; Leu, P.; Lohrmann, E.; Pandoulas, D.; Poelz, G.; Poesnecker, K.U.; Wiik, B.H.; Baranko, G.; Caldwell, A.; Cherney, M.; Izen, J.M.; Mermikides, M.; Ritz, S.; Rudolph, G.; Strom, D.; Takashima, M.; Venkataramania, H.; Wicklund, E.; Sau Lan Wu; Zobernig, G.

    1984-01-01

    The reaction e + e - ->e + e - eta'(958) has been observed by detecting the final state π + π - γ. The two-photon width of the eta' has been measured to be GAMMA(eta'->γγ)=5.1+-0.4+-0.7 keV. A search for the iota(1440) has been made in the rho 0 γ final state. An upper limit has been obtained for the product GAMMA(iota(1440)->γγ), B(iota->rho 0 γ)<1.5 keV (95% CL). (orig.)

  16. Measurement of K/sup +/ K/sup -/ production in two-photon collisions at Belle

    CERN Document Server

    Uehara, S

    2001-01-01

    K/sup +/K/sup -/ production in two-photon collisions has been studied with the Belle detector at KEKB. We have obtained the first high statistics data sample in the invariant mass range above 16 GeV. We report preliminary results of the cross section for gamma gamma to K /sup +/K/sup -/ in the c.m energy range between 136 and 230 GeV. In addition, we also present preliminary results for the gamma gamma to K /sub S//sup 0/K/sub S//sup 0/ process.

  17. Enhancement of two-photon photoluminescence and SERS for low-coverage gold films

    DEFF Research Database (Denmark)

    Novikov, Sergey M.; Beermann, Jonas; Frydendahl, Christian

    2016-01-01

    Electromagnetic field enhancement (FE) effects occurring in thin gold films 3-12-nm are investigated with two-photon photoluminescence (TPL) and Raman scanning optical microscopies. The samples are characterized using scanning electron microscopy images and linear optical spectroscopy. TPL images...... exhibit a strong increase in the level of TPL signals for films thicknesses 3-8-nm, near the percolation threshold. For some thicknesses, TPL measurements reveal super-cubic dependences on the incident power. We ascribe this feature to the occurrence of very strongly localized and enhanced electromagnetic...

  18. Two-photon fabrication of hydrogel microstructures for excitation and immobilization of cells.

    Science.gov (United States)

    Hasselmann, Nils Frederik; Hackmann, Michael Jona; Horn, Wolfgang

    2017-12-29

    We investigate in vitro fabrication of hydrogel microstructures by two photon laser lithography for single cell immobilization and excitation. Fluorescent yeast cells are embedded in water containing the hydrogel precursor mixtures and cross-linking is used to selectively immobilize a particular cell. Cell viability within the hydrogel precursor is estimated using a life/dead assay and elastic and stiff hydrogel structures are fabricated, immobilizing cells in a microfluidic environment. Additionally, we demonstrate the illumination of cells by on-the-fly fabricated hydrogel waveguide networks connected to an external light source, thereby exciting a fluorescence signal in a single immobilized cell.

  19. Two-photon luminescence microscopy of field enhancement at gold nanoparticles

    DEFF Research Database (Denmark)

    Beermann, Jonas; Bozhevolnyi, Sergey I.

    2005-01-01

    Using a reflection scanning optical microscope detecting two-photon luminescence (TPL) we have imaged square gold bumps positioned in a periodic array either on a smooth gold film or directly on a glass substrate. The second-harmonic (SH) and TPL response from these structures show both...... polarization and wavelength dependence. The gold bumps on gold film showed extremely high sensitivity to the incident field, with the strongest TPL response from the gold bumps being enhanced nearly 103 times compared to the TPL response from the smooth gold surface. For gold bumps directly on glass...

  20. Vector meson pair production in two-photon collisions at ARGUS

    International Nuclear Information System (INIS)

    Patel, P.M.

    1989-01-01

    New ARGUS results on exclusive final states produced in two-photon interactions are presented. Measurements of the vector meson pairs ρ + ρ - , ωρ 0 , ωω, K* + K* - and K* 0 bar K* 0 , as well as a search for φρ 0 , φω and φφ, are described. The results are compared with theoretical models. It is concluded that none of the models tells the full story when one considers the ARGUS data on all the possible vector meson pairs constructed from the 1 - vector nonet. 17 references, 5 figures, 1 table

  1. Manipulation of a two-photon pump in superconductor - semiconductor heterostructures

    Science.gov (United States)

    Orth, Peter P.; Baireuther, Paul; Vekhter, Ilya; Schmalian, Joerg

    2014-03-01

    We investigate the photon statistics, entanglement and squeezing of a pn-junction sandwiched between two superconducting leads, and show that such an electrically-driven photon pump generates correlated and entangled pairs of photons. In particular, we demonstrate that the squeezing of the fluctuations in the quadrature amplitudes of the emitted light can be manipulated by changing the relative phase of the order parameters of the superconductors. This reveals how macroscopic coherence of the superconducting state can be used to tailor the properties of a two-photon state.

  2. Targeted two-photon photodynamic therapy for the treatment of subcutaneous tumors

    Science.gov (United States)

    Spangler, Charles W.; Starkey, Jean R.; Meng, Fanqing; Gong, Aijun; Drobizhev, Mikhail; Rebane, Aleksander; Moss, B.

    2005-04-01

    Photodynamic therapy (PDT) has developed into a mature technology over the past several years, and is currently being exploited for the treatment of a variety of cancerous tumors, and more recently for age-related wet macular degeneration of the eye. However, there are still some unresolved problems with PDT that are retarding a more general acceptance in clinical settings, and thus, for the most part, the treatment of most cancerous rumors still involves some combination of invasive surgery, chemotherapy and radiation treatment, particularly subcutaneous tumors. Currently approved PDT agents are activated in the Visible portion of the spectrum below 700 nm, Laser light in this spectral region cannot penetrate the skin more than a few millimeters, and it would be more desirable if PDT could be initiated deep in the Near-infrared (NIR) in the tissue transparency window (700-1000 nm). MPA Technologies, Inc. and Rasiris, Inc. have been co-developing new porphyrin PDT designed to have greatly enhanced intrinsic two-photon cross-sections (>800 GM units) whose two-photon absorption maxima lie deep in the tissue transparency window (ca. 780-850 nm), and have solubility characteristics that would allow for direct IV injection into animal models. Classical PDT also suffers from the lengthy time necessary for accumulation at the tumor site, a relative lack of discrimination between healthy and diseased tissue, particularly at the tumor margins, and difficulty in clearing from the system in a reasonable amount of time post-PDT. We have recently discovered a new design paradigm for the delivery of our two-photon activated PDT agents by incorporating the porphyrins into a triad ensemble that includes a small molecule targeting agent that directs the triad to over-expressed tumor receptor sites, and a NIR one-photon imaging agent that allows the tracking of the triad in terms of accumulation and clearance rates. We are currently using these new two-photon PDT triads in efficacy

  3. Two-Photon-Exchange Correction to Parity-Violating Elastic Electron-Proton Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Andrei Afanasev; Carl Carlson

    2005-02-01

    Higher-order QED effects play an important role in precision measurements of nucleon elastic form factors in electron scattering. Here we introduce a two-photon exchange QED correction to the parity-violating polarization asymmetry of elastic electron-proton scattering. We calculate this correction in the parton model using the formalism of generalized parton distributions, and demonstrate that it can reach several per cent in certain kinematics, becoming comparable in size with existing experimental measurements of strange-quark effects in the proton neutral weak current.

  4. Confocal Laser Scanning Microscopy and Two Photon Excitation Microscopy as Tools to Study Testate Amoebae

    Czech Academy of Sciences Publication Activity Database

    Burdíková, Zuzana; Čapek, Martin; Ostašov, Pavel; Mitchell, E.A.D.; Machač, Jiří; Kubínová, Lucie

    2010-01-01

    Roč. 16, Suppl.2 (2010), s. 1142-1143 ISSN 1431-9276. [Microscopy and Microanalysis 2010. Portland, 01.08.2010-05.08.2010] R&D Projects: GA MŠk(CZ) LC06063; GA ČR(CZ) GA102/08/0691; GA ČR(CZ) GA304/09/0733 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z60050516 Keywords : testate amoeba e * confocal microscopy * two-photon microscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.179, year: 2010

  5. Forward two-photon exchange in elastic lepton-proton scattering and hyperfine-splitting correction

    Energy Technology Data Exchange (ETDEWEB)

    Tomalak, Oleksandr [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2017-08-15

    We relate the forward two-photon exchange (TPE) amplitudes to integrals of the inclusive lepton-proton scattering cross sections. These relations yield an alternative way for the evaluation of the TPE correction to hyperfine-splitting (HFS) in the hydrogen-like atoms with an equivalent to the standard approach (Iddings, Drell and Sullivan) result implying the Burkhardt-Cottingham sum rule. For evaluation of the individual effects (e.g., elastic contribution) our approach yields a distinct result. We compare both methods numerically on examples of the elastic contribution and the full TPE correction to HFS in electronic and muonic hydrogen. (orig.)

  6. Whispering gallery modes in two-photon fluorescence from spherical DCM dye microresonators

    Science.gov (United States)

    Mamonov, Evgeniy A.; Maydykovskiy, Anton I.; Mitetelo, Nikolai V.; Venkatakrishnarao, Dasari; Chandrasekar, Rajadurai; Murzina, Tatyana V.

    2018-03-01

    Organic microstructures are well known for their resonator properties, which bring about whispering gallery mode (WGM) excitation. Here we report on experimental evidence of the WGM in the two-photon fluorescence (TPF) of DCM dye microspheres made using the self-assembly method. The WGM excitation accompanying the overall TPF in the spectral range from 530\\div640 nm demonstrated a quality factor of approximately 102 for spheres that were several microns in diameter. The power dependence of the TPF intensity proved the second order nature of the interaction process involved.

  7. Suitable photo-resists for two-photon polymerization using femtosecond fiber lasers

    KAUST Repository

    Rajamanickam, V.P.

    2014-06-01

    We present suitable materials with good optical and mechanical properties, simple processing, efficient and optimized for two-photon polymerization (TPP) with femtosecond fiber lasers. We selected readily available acrylic monomer Bisphenol A ethoxylate diacrylate (BPA-EDA) with three different photo-initiators (PIs), isopropyl thioxanthone (ITX), 7-diethylamino-3-thenoylcoumarin (DETC), and 4,4′ bis(diethylamino) benzophenone (BDEB), since their absorption spectra match well with the laser wavelength at 780 nm. These PIs grant efficient radical generation, reactivity and high solubility in acrylic monomers. Finally, good optical and mechanical properties are demonstrated by the fabrication of different micro-structures.

  8. Two photon laser spectroscopy of antiprotonic helium atoms at CERN’s AD

    CERN Document Server

    Hori, M

    2014-01-01

    The ASACUSA collaboration of CERN has carried out two-photon laser spectroscopy of antiprotonic helium atoms using counter-propagating ultraviolet laser beams. This excited some non-linear transitions of the antiproton at the wavelengths λ = 139.8–197.0 nm, in a way that reduced the thermal Doppler broadening of the observed resonances. The resulting narrow spectral lines allowed the measurement of three transition frequencies with fractional precisions of 2.3–5 parts in 109. By comparing these values with three-body QED calculations, the antiproton-to-electron mass ratio was derived as 1836.1526736(23). We briefly review these results.

  9. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    International Nuclear Information System (INIS)

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-01-01

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  10. Two-photon exchange interaction from the Dicke Hamiltonian under parametric modulation

    Science.gov (United States)

    Dodonov, A. V.

    2018-02-01

    We consider the nonstationary circuit QED architecture in which a single-mode cavity interacts with N >1 identical qubits, and some system parameters undergo a weak external perturbation. It is shown that in the dispersive regime one can engineer the two-photon exchange interaction by adjusting the frequency of harmonic modulation to (approximately) 2 | Δ-| , where Δ- is the average atom-field detuning. A closed analytic description is derived for the weak atom-field coupling regime, and the system dynamics under realistic conditions is studied numerically.

  11. Intensity of two-photon absorption transitions for Ni2+ in MgO

    International Nuclear Information System (INIS)

    Sztucki, J.; Daoud, M.; Kibler, M.

    1991-01-01

    The parity-allowed two-photon transitions between the ground state 3 A 2 (T 2 ) of the configuration 3d 8 in cubical symmetry and the excited states of the same configuration are obtained via a simple model. This model is developed in a symmetry adapted framework by using second-order mechanisms and ionic wave-functions. It is applied to the recent experimental results obtained by McClure and co-workers for Ni 2+ in MgO. (author) 21 refs.; 2 tabs

  12. Search for Standard Model Higgs boson in the two-photon final state in ATLAS

    Directory of Open Access Journals (Sweden)

    Davignon Olivier

    2012-06-01

    Full Text Available We report on the search for the Standard Model Higgs boson decaying into two photons based on proton-proton collision data with a center-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. The dataset has an integrated luminosity of about 1:08 fb−1. The expected cross section exclusion at 95% confidence level varies between 2:0 and 5:8 times the Standard Model cross section over the diphoton mass range 110 – 150 GeV. The maximum deviations from the background-only expectation are consistent with statistical fluctuations.

  13. $\\Lambda$ and $\\Sigma^{0}$ Pair Production in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

    2002-01-01

    Strange baryon pair production in two-photon collisions is studied with the L3 detector at LEP. The analysis is based on data collected at e+e- centre-of-mass energies from 91 GeV to 208 GeV, corresponding to an integrated luminosity of 844 pb-1. The processes gamma gamma -> Lambda Anti-lambda and gamma gamma -> Sigma0 Anti-sigma0 are identified. Their cross sections as a function of the gamma gamma centre-of-mass energy are measured and results are compared to predictions of the quark-diquark model.

  14. Muon-Pair and Tau-Pair Production in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, Stefan; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.Wang X.L.; Wang, Z.M.; Weber, M.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2004-01-01

    The QED processes e^+ e^- -> e^+ e^- \\mu^+ \\mu^- and e^+ e^- -> e^+ e^- \\tau^+ \\tau^- are studied with the L3 detector at LEP using an untagged data sample collected at centre-of-mass energies 161 GeV \\mu^+\\mu^- process is also measured as a function of the two-photon centre-of-mass energy for 3 GeV < W_{\\gamma\\gamma} < 40 GeV. Good agreement is found between these measurements and the O(\\alpha^4) QED expectations. In addition, limits on the anomalous magnetic and electric dipole moments of the tau lepton are extracted.

  15. Proton-Antiproton Pair Production in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2003-01-01

    The reaction e+e- -> e+e- proton antiproton is studied with the L3 detector at LEP. The analysis is based on data collected at e+e- center-of-mass energies from 183 GeV to 209 GeV, corresponding to an integrated luminosity of 667 pb-1. The gamma gamma -> proton antiproton differential cross section is measured in the range of the two-photon center-of-mass energy from 2.1 GeV to 4.5 GeV. The results are compared to the predictions of the three-quark and quark-diquark models.

  16. Measurement of the D*+/- cross section in two-photon processes

    Science.gov (United States)

    Enomoto, R.; Iwasaki, M.; Muramatsu, K.; Hayashii, H.; Miyamoto, A.; Itoh, R.; Abe, K.; Abe, T.; Adachi, I.; Aoki, M.; Awa, S.; Belusevic, R.; Emi, K.; Fujii, H.; Fujii, K.; Fujii, T.; Fujimoto, J.; Fujita, K.; Fujiwara, N.; Howell, B.; Iida, N.; Ikeda, H.; Iwasaki, H.; Kajikawa, R.; Kato, S.; Kawabata, S.; Kichimi, H.; Kobayashi, M.; Koltick, D.; Levine, I.; Miyabayashi, K.; Nagai, K.; Nagira, T.; Nakano, E.; Nakabayashi, K.; Nitoh, O.; Noguchi, S.; Ochiai, F.; Ohnishi, Y.; Okuno, H.; Okusawa, T.; Shimozawa, K.; Shinohara, T.; Sugiyama, A.; Sugiyama, N.; Suzuki, S.; Takahashi, K.; Takahashi, T.; Takemoto, M.; Tanimori, T.; Tauchi, T.; Teramae, F.; Teramoto, Y.; Toomi, N.; Toyama, T.; Tsukamoto, T.; Uno, S.; Watanabe, Y.; Yamaguchi, A.; Yamamoto, A.; Yamauchi, M.

    1994-08-01

    We have measured the inclusive D*+/- production cross secton in a two-photon collision at the KEK e+e- collider TRISTAN. The mean √s of the collider was 57.16 GeV and the integrated luminosity was 150 pb-1. The differential cross section [dσ(D*+/-)/dPT] was obtained in the PT range between 1.6 and 6.6 GeV and compared with theoretical predictions, such as those involving direct and resolved photon processes.

  17. Exclusive two-photon processes: Tests of QCD at the amplitude level

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1992-07-01

    Exclusive two-photon processes at large momentum transfer, particularly Compton scattering γp→γp and its crossed-channel reactions γγ→ bar pp and bar pp→γγ, can provide definitive information on the bound-state distributions of quarks in hadrons at the amplitude level. Recent theoretical work has shown that QCD predictions based on the factorization of long and short distance physics are already applicable at momentum transfers of order of a few GeV

  18. Correlated two-photon interference in a dual-beam Michelson interferometer

    International Nuclear Information System (INIS)

    Kwiat, P.G.; Vareka, W.A.; Hong, C.K.; Nathel, H.; Chiao, R.Y.

    1990-01-01

    We report on an interference effect arising from a two-photon entangled state produced in a potassium dihydrogen phosphate (KDP) crystal pumped by an ultraviolet argon-ion laser. Two conjugate beams of signal and idler photons were injected in a parallel configuration into a single Michelson interferometer, and detected separately by two photomultipliers, while the difference in its arm lengths was slowly scanned. The coincidence rate exhibited fringes with a visibility of nearly 50%, and a period given by half the ultraviolet (not the signal or idler) wavelength, while the singles rate exhibited no fringes

  19. One-bit photon polarization in two-photon experiments. An information mechanics perspective

    International Nuclear Information System (INIS)

    Kantor, F.W.

    1991-01-01

    In this paper is presented a detailed treatment of amount and representation of photon polarization information in the two-photon experiments of Aspect, Grangier, and Roger, seeking to test Einstein, Podolsky, and Rosen's thought experiment. Newton's mechanics, Einstein's relativistic mechanics, and quantum mechanics do not treat as fundamental the amount and representation of information in physical systems. The line of reasoning presented here was reached via Kantor's information mechanics. The information bookkeeping presented here appears to offer a simple, physical insight into what the apparatus and the photons are doing together

  20. Effects of Conjugation in Length and Dimension on Two-Photon Properties of Fluorene-Based Chromophores (Preprint)

    National Research Council Canada - National Science Library

    Pachter, Ruth; Nguyen, Kiet A; Day, Paul N; Kannan, Ramamurthi

    2007-01-01

    We report the computed two-photon (TPA) absorption spectra based upon the results obtained from quadratic response time-dependent density functional theory for fluorine-based donor-pi-acceptor molecules...

  1. Synthesis, nonlinear optical properties and the possible mechanism of photopolymerization of two new two-photon absorption chromophores

    International Nuclear Information System (INIS)

    Yan Yunxing; Tao Xutang; Sun Yuanhong; Xu Guibao; Wang Chuankui; Yang Jiaxiang; Zhao Xian; Jiang Minhua

    2004-01-01

    Efficient Witting and Pd-catalyzed Heck coupling methodologies are employed to synthesize two new two-photon free-radical photopolymerization initiators 9-ethyl-3-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-9H-carbazole (abbreviated to EPVPC) and 9-octadecyl-3-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-9H-carbazole (abbreviated to OPVPC). The experimental results confirm that the two compounds are good two-photon absorbing chromophores and operative two-photon photopolymerization initiators. The calculated two-photon absorption cross-sections of EPVPC and OPVPC are 56.6 and 62.0x10 -50 cm 4 s photon -1 , respectively. A microstructure by using EPVPC as initiator has been fabricated under irradiation of 200 fs, 76 MHz Ti:sapphire femtosecond laser at 780 nm. The possible mechanism of photopolymerization is discussed

  2. Two-photon induced fluorescence of Cy5-DNA in buffer solution and on silver island films

    International Nuclear Information System (INIS)

    Lukomska, Joanna; Gryczynski, Ignacy; Malicka, Joanna; Makowiec, Slawomir; Lakowicz, Joseph R.; Gryczynski, Zygmunt

    2005-01-01

    We report the observation of a strong two-photon induced fluorescence emission of Cy5-DNA within the tunable range of a Ti:Sapphire laser. The estimated two-photon cross-section for Cy5-DNA of 400 GM is about 3.5-fold higher than it was reported for rhodamine B. The fundamental anisotropies of Cy5-DNA are close to the theoretical limits of 2/5 and 4/7 for one- and two-photon excitation, respectively. We also observed an enhanced two-photon induced fluorescence (TPIF) of Cy5-DNA deposited on silver island films (SIFs). In the presence of SIFs, the TPIF is about 100-fold brighter. The brightness increase of Cy5-DNA TPIF near SIFs is mostly due to enhanced local field

  3. In situ electrical and thermal monitoring of printed electronics by two-photon mapping.

    Science.gov (United States)

    Pastorelli, Francesco; Accanto, Nicolò; Jørgensen, Mikkel; van Hulst, Niek F; Krebs, Frederik C

    2017-06-19

    Printed electronics is emerging as a new, large scale and cost effective technology that will be disruptive in fields such as energy harvesting, consumer electronics and medical sensors. The performance of printed electronic devices relies principally on the carrier mobility and molecular packing of the polymer semiconductor material. Unfortunately, the analysis of such materials is generally performed with destructive techniques, which are hard to make compatible with in situ measurements, and pose a great obstacle for the mass production of printed electronics devices. A rapid, in situ, non-destructive and low-cost testing method is needed. In this study, we demonstrate that nonlinear optical microscopy is a promising technique to achieve this goal. Using ultrashort laser pulses we stimulate two-photon absorption in a roll coated polymer semiconductor and map the resulting two-photon induced photoluminescence and second harmonic response. We show that, in our experimental conditions, it is possible to relate the total amount of photoluminescence detected to important material properties such as the charge carrier density and the molecular packing of the printed polymer material, all with a spatial resolution of 400 nm. Importantly, this technique can be extended to the real time mapping of the polymer semiconductor film, even during the printing process, in which the high printing speed poses the need for equally high acquisition rates.

  4. Luminosity measurements at LHCb using dimuon pairs produced via elastic two photon fusion.

    CERN Document Server

    Anderson, J

    2010-01-01

    This note outlines the feasibility of using the elastic two photon process pp$\\rightarrow$ p+$\\mu^{+}\\mu^{-}+p$ to make luminosity measurements at LHCb. The overall efficiency at LHCb for recording and selecting pp$\\rightarrow$ p+$\\mu^{+}\\mu^{-}+p$ events produced within 1.6<$\\eta$<5 has been determined using Monte-Carlo to be 0.0587 $\\pm$ 0.0008, yielding 5210$\\pm$71(stat.) events for an integrated luminosity of 1fb$^{-1}$. The main background processes where dimuons are produced via inelastic two-photon fusion and double Pomeron exchange have been studied using the full LHCb detector simulation while the other background sources, including backgrounds caused by K/$\\pi$ mis-identification, have been studied at four vector level. The background is estimated to be (4.1 $\\pm$ 0.5(stat.) $\\pm$ 0.6(syst.))% of the signal level. Most of this background comes from K/$\\pi$ mis-identification, although the largest source of uncertainty in the estimation is due to knowledge of the number of events produced via d...

  5. Human infrared vision is triggered by two-photon chromophore isomerization

    Science.gov (United States)

    Palczewska, Grazyna; Vinberg, Frans; Stremplewski, Patrycjusz; Bircher, Martin P.; Salom, David; Komar, Katarzyna; Zhang, Jianye; Cascella, Michele; Wojtkowski, Maciej; Kefalov, Vladimir J.; Palczewski, Krzysztof

    2014-01-01

    Vision relies on photoactivation of visual pigments in rod and cone photoreceptor cells of the retina. The human eye structure and the absorption spectra of pigments limit our visual perception of light. Our visual perception is most responsive to stimulating light in the 400- to 720-nm (visible) range. First, we demonstrate by psychophysical experiments that humans can perceive infrared laser emission as visible light. Moreover, we show that mammalian photoreceptors can be directly activated by near infrared light with a sensitivity that paradoxically increases at wavelengths above 900 nm, and display quadratic dependence on laser power, indicating a nonlinear optical process. Biochemical experiments with rhodopsin, cone visual pigments, and a chromophore model compound 11-cis-retinyl-propylamine Schiff base demonstrate the direct isomerization of visual chromophore by a two-photon chromophore isomerization. Indeed, quantum mechanics modeling indicates the feasibility of this mechanism. Together, these findings clearly show that human visual perception of near infrared light occurs by two-photon isomerization of visual pigments. PMID:25453064

  6. Two-Photon Absorption Spectroscopy of Rubidium with a Dual-Comb Tequnique

    Science.gov (United States)

    Nishiyama, Akiko; Yoshida, Satoru; Hariki, Takuya; Nakajima, Yoshiaki; Minoshima, Kaoru

    2017-06-01

    Dual-comb spectroscopies have great potential for high-resolution molecular and atomic spectroscopies, thanks to the broadband comb spectrum consisting of dense narrow modes. In this study, we apply the dual-comb system to Doppler-free two-photon absorption spectroscopy. The outputs of two frequency combs excite several two-photon transitions of rubidium, and we obtained broadband Doppler-free spectra from dual-comb fluorescence signals. The fluorescence detection scheme circumvents the sensitivity limit which is effectively determined by the dynamic range of photodetectors in absorption-based dual-comb spectroscopies. Our system realized high-sensitive, Doppler-free high-resolution and broadband atomic spectroscopy. A part of observed spectra of 5S_{1/2} - 5D_{5/2} transition is shown in the figure. The hyperfine structures of the F" = 1 - F' = 3,2,1 transitions are fully-resolved and the spectral widths are approximately 5 MHz. The absolute frequency axis is precisely calibrated from comb mode frequencies which were stabilized to a GPS-disciplined clock. This work was supported by JST through the ERATO MINOSHIMA Intelligent Optical Synthesizer Project and Grant-in-Aid for JSPS Fellows (16J02345). A. Nishiyama, S. Yoshida, Y. Nakajima, H. Sasada, K. Nakagawa, A. Onae, K. and Minoshima, Opt. Express 24, 25894 (2016). A. Hipke, S. A. Meek, T. Ideguchi, T.W. Hänsch, and N. Picqué, Phys. Rev. A 90, 011805(R) (2014).

  7. Simultaneous morphological and functional imaging of the honeybee's brain by two-photon microscopy

    International Nuclear Information System (INIS)

    Haase, A.

    2011-01-01

    Thanks to its rather simply structured but highly performing brain, the honeybee (Apis mellifera) is an important model for neurobiological studies. Therefore there is a great need for new functional imaging modalities adapted to this species. Herein we give a detailed report on the development and performance of a platform for in vivo functional and morphological imaging of the honeybee's brain, focusing on its primary olfactory centres, the antennal lobes (ALs). The experimental setup consists of a two-photon microscope combined with a synchronized odour stimulus generator. Our imaging platform allows to simultaneously obtain both morphological measurements of the ALs functional units, the glomeruli, and in vivo calcium recording of their neural activity. We were able to record the characteristic glomerular response maps to odour stimuli applied to the bee's antennae. Our approach offers several advantages over the commonly used conventional fluorescence microscopy. Two-photon microscopy provides substantial enhancement in both spatial and temporal resolutions, while minimizing photo damage. Calcium recordings show a more than fourfold improvement in the functional signal with respect to the techniques available up to now. Finally, the extended penetration depth, thanks to the infrared excitation, allows the functional imaging of profound glomeruli which have not been optically accessible up to now.

  8. Controlling nonclassical properties of the two-photon process by a time-varying field

    International Nuclear Information System (INIS)

    Fei, Jia; Shuang-Yuan, Xie; Ya-Ping, Yang

    2009-01-01

    The interactions between a two-level atom and a field via two-photon transition without rotating wave approximation have been investigated. We emphasize the dynamic behaviors of the atomic population inversion, the field squeezing, and the atomic dipole squeezing numerically when the field frequency varies with time in the forms of sine and rectangle. Some interesting phenomena are discovered and discussed. The good periodic character of the atomic population inversion in the standard two-photon Jaynes–Cummings model is weakened by the influence of the sine field frequency modulation. The rectangular field frequency modulation can change the correlation among different oscillations suddenly and induce new collapse-revival processes of the atomic population inversion. The field squeezing increases at the beginning of time, but then decreases and loses as the time increases after it reaches the maximum due to the sine modulation. The effects of the rectangular modulation on the field squeezing depend mostly on the appearance time of the modulation. The atomic dipole squeezing is weakened under the influence of the sine or rectangular modulation. Our results indicate that it is possible to perform the dynamic controlling of the system properties by changing the parameters of the system with time. This implies that one can dynamically control a quantum information process by choosing the system modulation properly. (general)

  9. Pattern generation using axicon lens beam shaping in two-photon polymerisation

    Science.gov (United States)

    Bhuian, B.; Winfield, R. J.; O'Brien, S.; Crean, G. M.

    2007-12-01

    The fabrication of three-dimensional microstructures by two-photon polymerisation has been widely reported as a viable route to the development of photonic crystals, rotors, bridges and other complex artefacts requiring nanoscale resolution. Conventionally, single point serial writing is used to write the structures but recently multipoint beam delivery using beam division optics has been reported as a method of introducing parallel processing. In this paper we present an alternative and novel approach using an axicon lens to give profiled beam delivery. This enables complete three-dimensional annular structure fabrication without the use of scanning stages. In addition, the concept of axicon delivery is developed further to investigate three-dimensional structure as a function of axicon geometry. A Ti:sapphire laser, with wavelength 795 nm, 80 MHz repetition rate, 100 fs pulse duration and an average power of 700 mW, was used to initiate two-photon polymerisation. The axicon was used, in combination with a 100× microscope objective, to form representative three-dimensional structures based on the annular cell with varying diameter. The structures were written in a Zr-loaded resin prepared on a glass substrate using dip coating deposition of a Zr/PMMA hybrid prepared by the sol-gel method. Annuli with diameters up to 50 μm were characterised in terms of topography and surface roughness using SEM and Zygo interferometer. The writing technique was also extended to fabrication of stacked structures.

  10. Pattern generation using axicon lens beam shaping in two-photon polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Bhuian, B. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland); Department of Microelectronic Engineering, University College Cork, Cork (Ireland); Winfield, R.J. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)], E-mail: richard.winfield@tyndall.ie; O' Brien, S. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland); Crean, G.M. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland); Department of Microelectronic Engineering, University College Cork, Cork (Ireland)

    2007-12-15

    The fabrication of three-dimensional microstructures by two-photon polymerisation has been widely reported as a viable route to the development of photonic crystals, rotors, bridges and other complex artefacts requiring nanoscale resolution. Conventionally, single point serial writing is used to write the structures but recently multipoint beam delivery using beam division optics has been reported as a method of introducing parallel processing. In this paper we present an alternative and novel approach using an axicon lens to give profiled beam delivery. This enables complete three-dimensional annular structure fabrication without the use of scanning stages. In addition, the concept of axicon delivery is developed further to investigate three-dimensional structure as a function of axicon geometry. A Ti:sapphire laser, with wavelength 795 nm, 80 MHz repetition rate, 100 fs pulse duration and an average power of 700 mW, was used to initiate two-photon polymerisation. The axicon was used, in combination with a 100x microscope objective, to form representative three-dimensional structures based on the annular cell with varying diameter. The structures were written in a Zr-loaded resin prepared on a glass substrate using dip coating deposition of a Zr/PMMA hybrid prepared by the sol-gel method. Annuli with diameters up to 50 {mu}m were characterised in terms of topography and surface roughness using SEM and Zygo interferometer. The writing technique was also extended to fabrication of stacked structures.

  11. Two-photon absorption and upconversion luminescence of colloidal CsPbX3 quantum dots

    Science.gov (United States)

    Han, Qiuju; Wu, Wenzhi; Liu, Weilong; Yang, Qingxin; Yang, Yanqiang

    2018-01-01

    The nonlinear optical and the upconversion luminescence (UCL) properties of CsPbX3 (X = Br or its binary mixtures with Cl, I) quantum dots (QDs) are investigated by femtosecond open-aperture (OA) Z-scan and time-resolved luminescence techniques in nonresonant spectral region. The OA Z-scan results show that CsPbX3 QDs have strong reverse saturable absorption (RSA), which is ascribed to two-photon absorption. Partially changing halide composition from Cl to Br, to I, two-photon absorption cross sections become larger at the same laser excitation intensity. The composition-tunable nonlinear absorption should be attributed to the gradual decrease of the lowest direct band gaps with the halide substitute. Moreover, the strong UCL can be observed under near infrared femtosecond laser excitation. Halide composition-tunable UCL dynamics of CsPbX3 QDs is analyzed by use of two-exponential fitting with deconvolution. When CsPbX3 QDs have similar sizes (10-13 nm), with partially changing halide composition from Cl to Br, to I, the average UCL lifetime becomes longer due to the variation of Kane energy. Our findings suggest all-inorganic perovskite QDs can be used as excellent gain medium for high-performance frequency-upconversion lasers and provide reference to engineer such QDs toward practical optoelectronic applications.

  12. Two-photon induced fluorescence and other optical effects in irradiated and doped fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.D.

    1986-07-01

    The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10/sup 6/ rads (Si) of gamma rays and neutron fluences of 1 x 10/sup 14/ neutrons/cm/sup 2/. The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10/sup 9/ watts/cm/sup 2/ at a near infrared (1.06 ..mu..) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10/sup -10/%. 89 refs., 12 figs.

  13. Two-photon induced fluorescence and other optical effects in irradiated and doped fused silica

    International Nuclear Information System (INIS)

    Kramer, S.D.

    1986-07-01

    The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10 6 rads (Si) of gamma rays and neutron fluences of 1 x 10 14 neutrons/cm 2 . The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10 9 watts/cm 2 at a near infrared (1.06 μ) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10 -10 %. 89 refs., 12 figs

  14. The two-photon self-energy and other QED radiative corrections

    International Nuclear Information System (INIS)

    Zschocke, S.

    2001-07-01

    One of the main issues in current nuclear physics is the precise measurement of the Lamb shift of strongly bound electrons in quantum electrodynamic (QED) tests in strong fields in highly charged ions. The currently performed high-precision measurements require extreme accuracy in the theoretical calculation of Lamb shift. This requires consideration of all α and α 2 order QED corrections as well as of precisely all orders in Zα. In the past years most of these QED corrections have been calculated both in 1st order and in 2nd order interference theory. As yet however, it has not been possible to assess the contribution of the two-photon self-energy, which has therefore been the greatest uncertainty factor in predicting Lamb shift in hydrogen-like systems. This study examines the contribution of these processes to Lamb shift. It also provides the first ever derivation of renormalized terms of two-photon vacuum polarisation and self-energy vacuum polarisation. Until now it has only been possible to evaluate these contributions by way of an Uehling approximation [de

  15. Two-photon fluorescence biosensing with conventional and photonic crystal fibers

    Science.gov (United States)

    Myaing, Mon Thiri; Ye, Jing Yong; Norris, Theodore B.; Thomas, Thommey P.; Baker, James R., Jr.; Wadsworth, William J.; Bouwmans, Geraud; Knight, Jonathan C.; Russell, Philip S. J.

    2004-06-01

    Fluorescence is a powerful tool for biosensing, but conventional fluorescence measurements are limited because solid tumors are highly scattering media. To obtain quantitative in vivo fluorescence information from tumors, we have developed a two-photon optical fiber fluorescence (TPOFF) probe where excitation light is delivered and the two-photon fluorescence (TPF) excited at the tip of the fiber is collected back through the same fiber. In order to determine whether this system can provide quantitative information, we measured the fluorescence from a variety of systems including mouse tumors (both ex vivo and in vivo) which were transfected with the gene to express varying amounts of green fluorescence protein (GFP), and tumors which were labeled with targeted dendrimer-based drug delivery agents. The TPOFF technique showed results quantitatively in agreement with those from flow cytometry and confocal microscopy. In order to improve the sensitivity of our fiber probe, we developed a dual-clad photonic-crystal fiber which allowed single-mode excitation and multimode (high numerical aperture) collection of TPF. These experiments indicate that the TPOFF technique is highly promising for real-time, in vivo, quantitative fluorescence measurements.

  16. Diffraction and quantum control of wave functions in nonresonant two-photon absorption

    Science.gov (United States)

    Li, Baihong; Pang, Huafeng; Wang, Doudou; Zhang, Tao; Dong, Ruifang; Li, Yongfang

    2018-03-01

    In this study, the nonresonant two-photon absorption process in a two-level atom, induced by a weak chirped pulse, is theoretically investigated in the frequency domain. An analytical expression of the wave function expressed by Fresnel functions is obtained, and the two-photon transition probability (TPTP) versus the integral bandwidth, spectral width, and chirp parameter is analyzed. The results indicate that the oscillation evolution of the TPTP result from quantum diffraction of the wave function, which can be explained by analogy with Fresnel diffraction from a wide slit in the spatial domain. Moreover, the ratio between the real and imaginary parts of the excited state wave function and, hence, the atomic polarization, can be controlled by the initial phase of the excitation pulse. In some special initial phase of the excitation pulse, the wave functions with purely real or imaginary parts can be obtained by measuring the population probability. This work provides a novel perspective for understanding the physical details of the interactions between atoms and chirped light pulses in the multiphoton process.

  17. Two-photon microscopy of the mouse cochlea in situ for cellular diagnosis

    Science.gov (United States)

    Yang, Xin; Pu, Ye; Hsieh, Chia-Lung; Ong, Cheng Ai; Psaltis, Demetri; Stankovic, Konstantina M.

    2013-03-01

    Sensorineural hearing loss is the most common type of hearing loss worldwide, yet the underlying cause is typically unknown because the inner ear cannot be biopsied today without destroying hearing, and intracochlear cells have not been imaged with resolution sufficient to establish diagnosis. Intracochlear imaging has been technologically challenging because of the cochlea's small size and encasement in bone. We report, for the first time, imaging of the mouse cochlea in situ without exogenous dyes, through a membranous round window, using a near-infrared femtosecond laser as the excitation and endogenous two-photon excitation fluorescence (TPEF) and second harmonic generation as the contrast mechanisms. We find that TPEF exhibits strong contrast allowing cellular, and even subcellular resolution, and detection of specific, noise-induced pathologic changes. Our results demonstrate that the round window provides a useful access to the cochlea through the middle ear, and they motivate future development of a new and efficient diagnostic tool based on two-photon micro-endoscopy.

  18. Charge Transport in Two-Photon Semiconducting Structures for Solar Fuels.

    Science.gov (United States)

    Liu, Guohua; Du, Kang; Haussener, Sophia; Wang, Kaiying

    2016-10-20

    Semiconducting heterostructures are emerging as promising light absorbers and offer effective electron-hole separation to drive solar chemistry. This technology relies on semiconductor composites or photoelectrodes that work in the presence of a redox mediator and that create cascade junctions to promote surface catalytic reactions. Rational tuning of their structures and compositions is crucial to fully exploit their functionality. In this review, we describe the possibilities of applying the two-photon concept to the field of solar fuels. A wide range of strategies including the indirect combination of two semiconductors by a redox couple, direct coupling of two semiconductors, multicomponent structures with a conductive mediator, related photoelectrodes, as well as two-photon cells are discussed for light energy harvesting and charge transport. Examples of charge extraction models from the literature are summarized to understand the mechanism of interfacial carrier dynamics and to rationalize experimental observations. We focus on a working principle of the constituent components and linking the photosynthetic activity with the proposed models. This work gives a new perspective on artificial photosynthesis by taking simultaneous advantages of photon absorption and charge transfer, outlining an encouraging roadmap towards solar fuels. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Two-photon absorption cross section of magnetite nanoparticles in magnetic colloids and thin films

    Science.gov (United States)

    Espinosa, D.; Gonçalves, E. S.; Figueiredo Neto, A. M.

    2017-01-01

    We present z-scan measurements of magnetic nanoparticles made from magnetite in both thin film form and colloidal solutions. In order to avoid heating and, thus, spurious effects that could lead to misinterpretation of the z-scan results, an electro-mechanical shutter was added along the beam path in order to guarantee samples thermal relaxation. Two photon absorption coefficient β and nonlinear refractive index n2 were measured as a function of concentration N of absorbing units (Fe3O4). Our magnetite samples presented n 2 ≈ - 1.5 × 10 - 14 cm 2 / W , similar to that of the liquid carrier, for concentrations below 2 × 10 20 cm - 3 . n2 increases, in absolute value, to about - 10 × 10 - 14 cm 2 / W for a sample three times more concentrated and then decreases with N until about - 7 × 10 - 14 cm 2 / W for the most concentrated sample. β presented a linear dependence with N and the two-photon absorption cross section σ 2 PA was calculated, resulting in σ 2 PA = 50 ( 2 ) GM for magnetite nanoparticles.

  20. New method for measuring low NO concentrations using laser induced two photon ionization

    Science.gov (United States)

    Lee, Shan-Hu; Hirokawa, Jun; Kajii, Yoshizumi; Akimoto, Hajime

    1997-07-01

    A new method based on laser induced two photon ionization was developed for detection of low levels of NO concentration in the troposphere. A frequency-doubled pulsed dye laser operating at near 226 nm was used to photoionize NO by a (1+1) resonance enhanced two photon ionization via its A 2Σ←X2Π(0,0) band. NO ions are detected by an electron multiplier. Air gas samples are injected through a pulsed nozzle into a vacuum chamber. Cooling of rovibrational levels during the expansion process allows better selectivity for NO detection from other nitrocompounds. Measurement conditions were optimized as a function of X/D for the nozzle (X is the distance from the nozzle orifice to the ionization area, and D is the diameter of the nozzle orifice), laser power, and electron multiplier voltage. For the first time, selectivities for NO measurement, which were obtained from ion intensity ratios of NO and other nitrocompounds such as NO2 at the same concentrations, are discussed. A selectivity of 45 for NO vs NO2 was obtained using a 44 μJ pulse energy and an X/D of 120 for the nozzle. The current detection limit determined for NO was 16 pptv with an integration time of 1 min and a pulse energy of 44 μJ.

  1. Search for New Physics with Two Photons in the Final State with the ATLAS Detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00441752

    This thesis reports on the search for new physics in the diphoton decay channel with the proton-proton collision data collected by ATLAS at a centre-of-mass energy of $\\sqrt{s}=8$~TeV in 2012 and $\\sqrt{s}=13$~TeV in 2015 and 2016. A feasibility study of the search for a pseudoscalar $A$ decaying to a $Z$ boson and a 125~GeV Higgs boson in the context of an extended Higgs sector, namedly the two-Higgs-doublet models, is presented. The search is performed with a final state of two jets and two photons using 20.3~${\\rm fb}^{-1}$ of data at $\\sqrt{s}=8$~TeV. The expected sensitivity is found to be competitive with the analysis with a final state of two electrons or muons and two $\\tau$ leptons, but less sensitive to the other searches with the Higgs decaying to a pair of $b$-quarks. Search for high mass resonances decaying to two photons at $\\sqrt{s}=13$~TeV is also presented. The analysed dataset corresponds to an integrated luminosity of $3.2~{\\rm fb}^{-1}$ in 2015 and $12.2~{\\rm fb}^{-1}$ in 2016. Two searche...

  2. Double-Tag Events in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Buijs, A.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; van Dierendonck, D.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duinker, P.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

    2002-01-01

    Double-tag events in two-photon collisions are studied using the L3 detector at LEP centre-of-mass energies from root(s)=189 GeV to 209 GeV. The cross sections of the e+e- -> e+e- hadrons and gamma*gamma* -> hadrons processes are measured as a function of the photon virtualities, Q2_1 and Q2_2, of the two-photon mass, W_gammagamma, and of the variable Y=ln(W2_gammagamma/(Q_1Q_2)), for an average photon virtuality = 16 GeV2. The results are in agreement with next-to-leading order calculations for the process gamma*gamma* -> q qbar in the interval 2 <= Y <= 5. An excess is observed in the interval 5 < Y <= 7, corresponding to W_gammagamma greater than 40 GeV . This may be interpreted as a sign of resolved photon QCD processes or the onset of BFKL phenomena.

  3. Resonant two-photon absorption and electromagnetically induced transparency in open ladder-type atomic system.

    Science.gov (United States)

    Moon, Han Seb; Noh, Heung-Ryoul

    2013-03-25

    We have experimentally and theoretically studied resonant two-photon absorption (TPA) and electromagnetically induced transparency (EIT) in the open ladder-type atomic system of the 5S(1/2) (F = 1)-5P(3/2) (F' = 0, 1, 2)-5D(5/2) (F″ = 1, 2, 3) transitions in (87)Rb atoms. As the coupling laser intensity was increased, the resonant TPA was transformed to EIT for the 5S(1/2) (F = 1)-5P(3/2) (F' = 2)-5D(5/2) (F″ = 3) transition. The transformation of resonant TPA into EIT was numerically calculated for various coupling laser intensities, considering all the degenerate magnetic sublevels of the 5S(1/2)-5P(3/2)-5D(5/2) transition. From the numerical results, the crossover from TPA to EIT could be understood by the decomposition of the spectrum into an EIT component owing to the pure two-photon coherence and a TPA component caused by the mixed term.

  4. Hard two-photon contribution to elastic lepton-proton scattering determined by the OLYMPUS experiment

    International Nuclear Information System (INIS)

    Henderson, B.S.; Ice, L.D.; Khaneft, D.

    2016-12-01

    The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R 2γ , a direct measure of the contribution of hard two- photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ∼20 to 80 . The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved GEM and MWPC detectors at 12 , as well as symmetric Moeller/Bhabha calorimeters at 1.29 . A total integrated luminosity of 4.5 fb -1 was collected. In the extraction of R 2γ , radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R 2γ , presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.

  5. Fully integrated reflection-mode photoacoustic, two-photon, and second harmonic generation microscopy in vivo

    Science.gov (United States)

    Song, Wei; Xu, Qiang; Zhang, Yang; Zhan, Yang; Zheng, Wei; Song, Liang

    2016-08-01

    The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain. Taking advantage of the complementary and comprehensive contrasts of the system, we demonstrated high-resolution imaging of various tissues in living mice, including microvasculature (by photoacoustics), epidermis cells, cortical neurons (by two-photon fluorescence), and extracellular collagen fibers (by SHG). The intrinsic image co-registration of the three modalities conveniently provided improved visualization and understanding of the tissue microarchitecture. The reported results suggest that, by revealing complementary tissue microstructures in vivo, this multimodal microscopy can potentially facilitate a broad range of biomedical studies, such as imaging of the tumor microenvironment and neurovascular coupling.

  6. Efficient Entanglement Concentration of Nonlocal Two-Photon Polarization-Time-Bin Hyperentangled States

    Science.gov (United States)

    Wang, Zi-Hang; Yu, Wen-Xuan; Wu, Xiao-Yuan; Gao, Cheng-Yan; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo

    2018-03-01

    We present two different hyperentanglement concentration protocols (hyper-ECPs) for two-photon systems in nonlocal polarization-time-bin hyperentangled states with known parameters, including Bell-like and cluster-like states, resorting to the parameter splitting method. They require only one of two parties in quantum communication to operate her photon in the process of entanglement concentration, not two, and they have the maximal success probability. They work with linear optical elements and have good feasibility in experiment, especially in the case that there are a big number of quantum data exchanged as the parties can obtain the information about the parameters of the nonlocal hyperentangled states by sampling a subset of nonlocal hyperentangled two-photon systems and measuring them. As the quantum state of photons in the time-bin degree of freedom suffers from less noise in an optical-fiber channel, these hyper-ECPs may have good applications in practical long-distance quantum communication in the future.

  7. Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

    International Nuclear Information System (INIS)

    Pastells, Carme; Marco, M.-Pilar; Merino, David; Loza-Alvarez, Pablo; Pasquardini, Laura; Lunelli, Lorenzo; Pederzolli, Cecilia; Daldosso, Nicola; Farnesi, Daniele; Berneschi, Simone; Righini, Giancarlo C.; Quercioli, Franco; Nunzi Conti, Gualtiero; Soria, Silvia

    2016-01-01

    We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

  8. Polarised structure functions and two-photon physics at Super-B

    Energy Technology Data Exchange (ETDEWEB)

    Shore, G.M. [Swansea University, Department of Physics, Swansea (United Kingdom)

    2013-03-15

    The potential of polarised, high-luminosity, moderate-energy e{sup +}e{sup -} colliders for performing unique measurements in fundamental QCD is described, with particular reference to the proposed Super-B facility. An extensive programme of two-photon physics is proposed, focusing on measurements of the polarised photon structure functions g{sub 1}{sup {gamma}} and g{sub 2}{sup {gamma}} and pseudoscalar meson transition functions. The experimental requirements for Super-B to make the first measurement of the first moment sum rule for the off-shell polarised photon structure function g{sub 1}{sup {gamma}}(x, Q{sup 2}; K{sup 2}) are described in detail. Cross-section formulae and experimental issues for investigations of NLO and higher-twist effects in g{sub 1}{sup {gamma}} and g{sub 2}{sup {gamma}} together with exclusive two-photon meson production are presented. This programme of QCD studies complements the core mission of Super-B as a high-luminosity B factory investigating flavour physics and rare processes signalling new physics beyond the standard model. (orig.)

  9. Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

    Energy Technology Data Exchange (ETDEWEB)

    Pastells, Carme; Marco, M.-Pilar [Nanobiotechnology for Diagnostics Group (Nb4Dg), IQAC-CSIC, 08034 Barcelona (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, 08034 Barcelona (Spain); Merino, David; Loza-Alvarez, Pablo [ICFO-Institut de Ciències Fotòniques, Castelldefels, 08860 Barcelona (Spain); Pasquardini, Laura [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Lunelli, Lorenzo [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); IBF-CNR, 38123 Povo, TN (Italy); Pederzolli, Cecilia [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Daldosso, Nicola [Department of Computer Science, University of Verona, Strada le Grazie 15, 37134 Verona (Italy); Farnesi, Daniele [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Berneschi, Simone [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Righini, Giancarlo C. [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Quercioli, Franco [CNR-INO National Institute of Optics, Sesto Fiorentino, FI (Italy); Nunzi Conti, Gualtiero [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Soria, Silvia, E-mail: s.soria@ifac.cnr.it [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy)

    2016-02-15

    We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

  10. Hard two-photon contribution to elastic lepton-proton scattering determined by the OLYMPUS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, B.S. [Massachusetts Institute of Technology, Cambridge, MA (United States); Ice, L.D. [Arizona State Univ., Tempe, AZ (United States); Khaneft, D. [Mainz Univ. (Germany); Collaboration: OLYMPUS Collaboration; and others

    2016-12-15

    The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R{sub 2γ}, a direct measure of the contribution of hard two- photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ∼20 to 80 . The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved GEM and MWPC detectors at 12 , as well as symmetric Moeller/Bhabha calorimeters at 1.29 . A total integrated luminosity of 4.5 fb{sup -1} was collected. In the extraction of R{sub 2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R{sub 2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.

  11. Novel foamy origin for singlet fermion masses

    Science.gov (United States)

    Ellis, John; Mavromatos, Nick E.; Nanopoulos, Dimitri V.

    2017-10-01

    We show how masses for singlet fermions can be generated by interactions with a D-particle model of space-time foam inspired by brane theory. It has been shown previously by one of the authors (N. E. M.) that such interactions may generate dynamically small masses for charged fermions via the recoils of D-particle defects interacting with photons. In this work we consider the direct interactions of D-particle with uncharged singlet fermions such as right-handed neutrinos. Quantum fluctuations of the lattice of D-particles have massless vector (spin-one) excitations that are analogues of phonons. These mediate forces with the singlet fermions, generating large dynamical masses that may be communicated to light neutrinos via the seesaw mechanism.

  12. Polymeric photosensitizer-embedded self-expanding metal stent for repeatable endoscopic photodynamic therapy of cholangiocarcinoma.

    Science.gov (United States)

    Bae, Byoung-chan; Yang, Su-Geun; Jeong, Seok; Lee, Don Haeng; Na, Kun; Kim, Joon Mee; Costamagna, Guido; Kozarek, Richard A; Isayama, Hiroyuki; Deviere, Jacques; Seo, Dong Wan; Nageshwar Reddy, D

    2014-10-01

    Photodynamic therapy (PDT) is a new therapeutic approach for the palliative treatment of malignant bile duct obstruction. In this study, we designed photosensitizer-embedded self-expanding nonvascular metal stent (PDT-stent) which allows repeatable photodynamic treatment of cholangiocarcinoma without systemic injection of photosensitizer. Polymeric photosensitizer (pullulan acetate-conjugated pheophorbide A; PPA) was incorporated in self-expanding nonvascular metal stent. Residence of PPA in the stent was estimated in buffer solution and subcutaneous implantation on mouse. Photodynamic activity of PDT-stent was evaluated through laserexposure on stent-layered tumor cell lines, HCT-116 tumor-xenograft mouse models and endoscopic intervention of PDT-stent on bile duct of mini pigs. Photo-fluorescence imaging of the PDT-stent demonstrated homogeneous embedding of polymeric Pheo-A (PPA) on stent membrane. PDT-stent sustained its photodynamic activities at least for 2 month. And which implies repeatable endoscopic PDT is possible after stent emplacement. The PDT-stent after light exposure successfully generated cytotoxic singlet oxygen in the surrounding tissues, inducing apoptotic degradation of tumor cells and regression of xenograft tumors on mouse models. Endoscopic biliary in-stent photodynamic treatments on minipigs also suggested the potential efficacy of PDT-stent on cholangiocarcinoma. In vivo and in vitro studies revealed our PDT-stent, allows repeatable endoscopic biliary PDT, has the potential for the combination therapy (stent plus PDT) of cholangiocarcinoma. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Gold Nanocage-Photosensitizer Conjugates for Dual-Modal Image-Guided Enhanced Photodynamic Therapy

    Science.gov (United States)

    Srivatsan, Avinash; Jenkins, Samir V.; Jeon, Mansik; Wu, Zhijin; Kim, Chulhong; Chen, Jingyi; Pandey, Ravindra K.

    2014-01-01

    We have demonstrated that gold nanocage-photosensitizer conjugates can enable dual image-guided delivery of photosensitizer and significantly improve the efficacy of photodynamic therapy in a murine model. The photosensitizer, 3-devinyl-3-(1'-hexyloxyethyl)pyropheophorbide (HPPH), was noncovalently entrapped in the poly(ethylene glycol) monolayer coated on the surface of gold nanocages. The conjugate is stable in saline solutions, while incubation in protein rich solutions leads to gradual unloading of the HPPH, which can be monitored optically by fluorescence and photoacoustic imaging. The slow nature of the release in turn results in an increase in accumulation of the drug within implanted tumors due to the passive delivery of gold nanocages. Furthermore, the conjugate is found to generate more therapeutic singlet oxygen and have a lower IC50 value than the free drug alone. Thus the conjugate shows significant suppression of tumor growth as compared to the free drug in vivo. Short-term study showed neither toxicity nor phenotypical changes in mice at therapeutic dose of the conjugates or even at 100-fold higher than therapeutic dose of gold nanocages. PMID:24465274

  14. Riboflavin photosensitized oxidation of myoglobin

    DEFF Research Database (Denmark)

    Grippa, Juliana M.; de Zawadzki, Andressa; Grossi, Alberto Blak

    2014-01-01

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation......-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K = (1.2 ± 0.2) × 10 mol·L with ΔH = -112 ± 22 kJ·mol and ΔS = -296 ± 75 J·mol·K. For meat, riboflavin is concluded to be a photosensitizer for protein...

  15. Diffraction and low-$Q^{2}$ physics including two-photon physics

    CERN Document Server

    Erdmann, M

    1999-01-01

    Recent experimental results on the partonic structure of the photon and on the color singlet exchange in strong interaction processes are reviewed. At the LEP e/sup +/e/sup -/ and HERA ep colliders, complementary and consistent measurements have been achieved on the quark-gluon structure of quasi-real and virtual photons. At the HERA ep and Tevatron pp colliders, the quark-gluon configurations of the diffractive exchange is consistently found to have a large gluon component. The rate of diffractive interactions observed by the HERA and Tevatron experiments, however, is largely different and challenges explanation. (74 refs).

  16. Pesticide photolysis in prairie potholes: probing photosensitized processes.

    Science.gov (United States)

    Zeng, Teng; Arnold, William A

    2013-07-02

    Prairie pothole lakes (PPLs) are glacially derived, ecologically important water bodies found in central North America and represent a unique setting in which extensive agriculture occurs within wetland ecosystems. In the Prairie Pothole Region (PPR), elevated pesticide use and increasing hydrologic connectivity have raised concerns about the impact of nonpoint source agricultural pollution on the water quality of PPLs and downstream aquatic systems. Despite containing high dissolved organic matter (DOM) levels, the photoreactivity of the PPL water and the photochemical fate of pesticides entering PPLs are largely unknown. In this study, the photodegradation of sixteen pesticides was investigated in PPL waters sampled from North Dakota, under simulated and natural sunlight. Enhanced pesticide removal rates in the irradiated PPL water relative to the control buffer pointed to the importance of indirect photolysis pathways involving photochemically produced reactive intermediates (PPRIs). The steady-state concentrations of carbonate radical, hydroxyl radical, singlet oxygen, and triplet-excited state DOM were measured and second-order rate constants for reactions of pesticides with these PPRIs were calculated. Results from this study underscore the role of DOM as photosensitizer in limiting the persistence of pesticides in prairie wetlands through photochemical reactions.

  17. A near-infrared genetically targetable and activatable photosensitizer

    OpenAIRE

    He, Jianjun; Wang, Yi; Missinato, Maria A.; Onuoha, Ezenwa; Perkins, Lydia A.; Watkins, Simon C.; St. Croix, Claudette M.; Tsang, Michael; Bruchez, Marcel P.

    2016-01-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species (ROS) that can be utilized for functional manipulation of living cells, including protein inactivation, targeted damage introduction, and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer in...

  18. Reversible Disruption of Neuronal Mitochondria by Ischemic and Traumatic Injury Revealed by Quantitative Two-Photon Imaging in the Neocortex of Anesthetized Mice.

    Science.gov (United States)

    Kislin, Mikhail; Sword, Jeremy; Fomitcheva, Ioulia V; Croom, Deborah; Pryazhnikov, Evgeny; Lihavainen, Eero; Toptunov, Dmytro; Rauvala, Heikki; Ribeiro, Andre S; Khiroug, Leonard; Kirov, Sergei A

    2017-01-11

    Mitochondria play a variety of functional roles in cortical neurons, from metabolic support and neuroprotection to the release of cytokines that trigger apoptosis. In dendrites, mitochondrial structure is closely linked to their function, and fragmentation (fission) of the normally elongated mitochondria indicates loss of their function under pathological conditions, such as stroke and brain trauma. Using in vivo two-photon microscopy in mouse brain, we quantified mitochondrial fragmentation in a full spectrum of cortical injuries, ranging from severe to mild. Severe global ischemic injury was induced by bilateral common carotid artery occlusion, whereas severe focal stroke injury was induced by Rose Bengal photosensitization. The moderate and mild traumatic injury was inflicted by focal laser lesion and by mild photo-damage, respectively. Dendritic and mitochondrial structural changes were tracked longitudinally using transgenic mice expressing fluorescent proteins localized either in cytosol or in mitochondrial matrix. In response to severe injury, mitochondrial fragmentation developed in parallel with dendritic damage signified by dendritic beading. Reconstruction from serial section electron microscopy confirmed mitochondrial fragmentation. Unlike dendritic beading, fragmentation spread beyond the injury core in focal stroke and focal laser lesion models. In moderate and mild injury, mitochondrial fragmentation was reversible with full recovery of structural integrity after 1-2 weeks. The transient fragmentation observed in the mild photo-damage model was associated with changes in dendritic spine density without any signs of dendritic damage. Our findings indicate that alterations in neuronal mitochondria structure are very sensitive to the tissue damage and can be reversible in ischemic and traumatic injuries. During ischemic stroke or brain trauma, mitochondria can either protect neurons by supplying ATP and adsorbing excessive Ca 2+ , or kill neurons by

  19. Ratiometric two-photon excited photoluminescence of quantum dots triggered by near-infrared-light for real-time detection of nitric oxide release in situ

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hui [Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, College of Chemistry and Chemical Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Shandong 266071 (China); Gui, Rijun, E-mail: guirijun@qdu.edu.cn [Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, College of Chemistry and Chemical Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Shandong 266071 (China); Sun, Jie; Wang, Yanfeng [Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan 250062 (China)

    2016-05-30

    Probe-donor integrated nanocomposites were developed from conjugating silica-coated Mn{sup 2+}:ZnS quantum dots (QDs) with MoS{sub 2} QDs and photosensitive nitric oxide (NO) donors (Fe{sub 4}S{sub 3}(NO){sub 7}{sup −}, RBS). Under excitation with near-infrared (NIR) light at 808 nm, the Mn{sup 2+}:ZnS@SiO{sub 2}/MoS{sub 2}-RBS nanocomposites showed the dual-emissive two-photon excited photoluminescence (TPEPL) that induced RBS photolysis to release NO in situ. NO caused TPEPL quenching of Mn{sup 2+}:ZnS QDs, but it produced almost no impact on the TPEPL of MoS{sub 2} QDs. Hence, the nanocomposites were developed as a novel QDs-based ratiometric TPEPL probe for real-time detection of NO release in situ. The ratiometric TPEPL intensity is nearly linear (R{sup 2} = 0.9901) with NO concentration in the range of 0.01∼0.8 μM, which corresponds to the range of NO release time (0∼15 min). The detection limit was calculated to be approximately 4 nM of NO. Experimental results confirmed that this novel ratiometric TPEPL probe possessed high selectivity and sensitivity for the detection of NO against potential competitors, and especially showed high detection performance for NIR-light triggered NO release in tumor intracellular microenvironments. These results would promote the development of versatile probe-donor integrated systems, also providing a facile and efficient strategy to real-time detect the highly controllable drug release in situ, especially in physiological microenvironments. - Highlights: • Mn{sup 2+}:ZnS@SiO{sub 2}/MoS{sub 2}-RBS nanocomposites were developed as a novel ratiometric two-photon excited fluorescence probe. • This probe could conduct real-time detection of nitric oxide release in situ. • High feasibility of this probe was confirmed in tumor intracellular microenvironments.

  20. Non-diagonal processes of singlet and ordinary quark production

    International Nuclear Information System (INIS)

    Bejlin, V.A.; Vereshkov, G.M.; Kuksa, V.I.

    1995-01-01

    Non-diagonal processes of singlet and ordinary quark production are analyzed in the model where the down singlet quark mixes with the ordinary ones. The possibility of experimental selection of h-quark effects is demonstrated

  1. Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Seipt, Daniel

    2012-12-20

    The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10{sup 24} W/cm{sup 2} and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton

  2. Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering

    International Nuclear Information System (INIS)

    Seipt, Daniel

    2012-01-01

    The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10 24 W/cm 2 and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton scattering. An

  3. Stability of O/W Emulsion with Synthetic Perfumes Oxidized by Singlet Oxygen

    Directory of Open Access Journals (Sweden)

    Naoki Watabe

    2013-01-01

    Full Text Available We prepared O/W emulsion composed of a synthetic perfume, n-dodecane, protoporphyrin IX disodium salt (PpIX-2Na, sodium dodecyl sulfate, and water and investigated oxidative decomposition of the synthetic perfume in the emulsion and change in the stability of the emulsion by singlet oxygen (1O2 generated by photosensitization of PpIX-2Na. We used eugenol, linalool, benzyl acetate, α-ionone, α-hexylcinnamaldehyde, and d-limonene as a synthetic perfume. The stability of the O/W emulation including eugenol and linalool significantly decreased with increasing light irradiation time. The decrease in the emulsion stability may be attributable to oxidative decomposition of eugenol and linalool by 1O2 and enlargement of the oil droplet size.

  4. Results on two-photon interactions from Mark II at SPEAR

    Energy Technology Data Exchange (ETDEWEB)

    Abrams, G.S.; Alam, M.S.; Blocker, C.A.

    1979-10-01

    Preliminary results on two-photon interactions from the SLAC-LBL Mark II magnetic detector at SPEAR are presented. The cross section for eta' production by the reaction e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/ eta' has been measured over the beam energy range from 2 to 4 GeV. The radiative width GAMMA/sub ..gamma gamma../(eta') has been determined to be 5.8 +- 1.1 keV (+- 20% systematic uncertainty). Upper limits on the radiative widths of the f(1270), and A/sub 2/(1310) and f'(1515) mesons have been determined.

  5. Two-photon Absorption In Quantum Dots,quantum Dashes And Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Ravinder

    2009-08-31

    We have proposed the use of USQDs for various deep-tissue biological imaging applications, notably wavelength-multiplexed multicolor imaging and intra-nuclear studies such as those involving cell apoptosis, and have studied the issue of maximizing two-photon absorption-induced fluorescence (TPAF) signals from CdSe/ZnS USQDs to be used for this application. In particular, using 2 nm USQDs, we have shown that the TPAF signal at 780 nm is ~ 8 times that at 850 nm and 68 times that at 900 nm, two wavelengths that have been used in previous studies using CdSe/ZnS SQDs for deep-tissue imaging of biological studies via TPAF .

  6. Hadronic cross-sections in two photon processes at a future linear collider

    International Nuclear Information System (INIS)

    Godbole, Rohini M.; Roeck, Albert de; Grau, Agnes; Pancheri, Giulia

    2003-01-01

    In this note we address the issue of measurability of the hadronic cross-sections at a future photon collider as well as for the two-photon processes at a future high energy linear e + e - collider. We extend, to higher energy, our previous estimates of the accuracy with which the γ γ cross-section needs to be measured, in order to distinguish between different theoretical models of energy dependence of the total cross-sections. We show that the necessary precision to discriminate among these models is indeed possible at future linear colliders in the Photon Collider option. Further we note that even in the e + e - option a measurement of the hadron production cross-section via γ γ processes, with an accuracy necessary to allow discrimination between different theoretical models, should be possible. We also comment briefly on the implications of these predictions for hadronic backgrounds at the future TeV energy e + e - collider CLIC. (author)

  7. Ultrafast two-photon absorption optical thresholding of spectrally coded pulses

    Science.gov (United States)

    Zheng, Z.; Shen, S.; Sardesai, H.; Chang, C.-C.; Marsh, J. H.; Karkhanehchi, M. M.; Weiner, A. M.

    1999-08-01

    We report studies on two-photon absorption (TPA) GaAs p-i-n waveguide photodetectors as optical thresholders for proposed ultrashort pulse optical code-division multiple-access (CDMA) systems. For either chirped optical pulses or spectrally phase coded pseudonoise bursts, the TPA photocurrent response reveals a strong pulseshape dependence and shows good agreement with theoretical predictions and results from conventional SHG measurements. The performance limits of the TPA optical thresholders set by the encoded bandwidth in the spectral encoding-decoding process are also discussed based on numerical simulations. Our results show the feasibility of applying such devices as nonlinear intensity discriminators in ultrahigh-speed optical network applications.

  8. Compact Optical Atomic Clock Based on a Two-Photon Transition in Rubidium

    Science.gov (United States)

    Martin, Kyle W.; Phelps, Gretchen; Lemke, Nathan D.; Bigelow, Matthew S.; Stuhl, Benjamin; Wojcik, Michael; Holt, Michael; Coddington, Ian; Bishop, Michael W.; Burke, John H.

    2018-01-01

    Extralaboratory atomic clocks are necessary for a wide array of applications (e.g., satellite-based navigation and communication). Building upon existing vapor-cell and laser technologies, we describe an optical atomic clock, designed around a simple and manufacturable architecture, that utilizes the 778-nm two-photon transition in rubidium and yields fractional-frequency instabilities of 4 ×10-13/√{τ (s ) } for τ from 1 to 10 000 s. We present a complete stability budget for this system and explore the required conditions under which a fractional-frequency instability of 1 ×10-15 can be maintained on long time scales. We provide a precise characterization of the leading sensitivities to external processes, including magnetic fields and fluctuations of the vapor-cell temperature and 778-nm laser power. The system is constructed primarily from commercially available components, an attractive feature from the standpoint of the commercialization and deployment of optical frequency standards.

  9. Partial angular coherence and the angular Schmidt spectrum of entangled two-photon fields

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Anand Kumar; Boyd, Robert W. [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Agarwal, Girish S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

    2011-12-15

    We study partially coherent fields that have a coherent-mode representation in the orbital-angular-momentum-mode basis. For such fields, we introduce the concepts of the angular coherence function and the coherence angle. Such fields are naturally produced by the process of parametric down-conversion--a second-order nonlinear optical process in which a pump photon breaks up into two entangled photons, known as the signal and idler photons. We show that the angular coherence functions of the signal and idler fields are directly related to the angular Schmidt (spiral) spectrum of the down-converted two-photon field and thus that the angular Schmidt spectrum can be measured directly by measuring the angular coherence function of either the signal or the idler field, without requiring coincidence detection.

  10. Full spectrum of the two-photon and the two-mode quantum Rabi models

    Energy Technology Data Exchange (ETDEWEB)

    Dossa, Anselme F., E-mail: anselme.dossa@imsp-uac.org, E-mail: ansdossa@gmail.com; Avossevou, Gabriel Y. H., E-mail: gabriel.avossevou@imsp-uac.org, E-mail: gavossevou@gmail.com [Unité de Recherche en Physique Théorique (URPT), Institut de Mathématiques et de Sciences Physiques (IMSP), Université d' Abomey-Calavi - UAC, 01 BP 613 Porto-Novo (Benin)

    2014-10-15

    This paper is concerned with the rigorous analytical determination of the spectrum of the two-photon and the two-mode quantum Rabi models. To reach this goal, we exploit the hidden symmetries in these models by means of the unitary and similarity transformations in addition to the Bargmann-Fock space description. In each case, the purely quantum mechanical problem of the Rabi model studied is reduced to solutions for differential equations. This eventually gives a third-order differential equation for each of these models, which is reduced to a second-order differential equation by additional transformations. The analytical expressions of the wave functions describing the energy levels are obtained in terms of the confluent hypergeometric functions.

  11. Observation of the two-photon decay of a light penetrating particle

    Science.gov (United States)

    Faissner, H.; Frenzel, E.; Heinrigs, W.; Preussger, A.; Samm, D.; Samm, U.

    1981-07-01

    Coincident two-photon events, emerging from a 2 m long decay region, and pointing back to the SIN 590 MeV proton beam dump were detected in a thin-foil optical spark chamber. There was a significant excess of photons at small angles ( Eγ1 Eγ2 front of the decay region, but vanished with the wall put at its end. Presumably a light boson χ 0 comes from the beam dump, penetrates the shielding, and decays: χ0 → 2 γ The measured rate of (14.5 ± 5.0) events in 129 Coulomb fixes a combination of production cross section and life-time. If the new boson χ 0 was the axion, one can solve for the Higgs parameter X = 3.0 ± 0.3, and infer τa ≈ 7 ms, and ma = (250 ± 25) keV.

  12. The $\\eta_c$(2980) formation in two-photon collisions at LEP energies

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alderweireld, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, Ugo; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Berntzon, L; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Bugge, L; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F R; Chapkin, M M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crawley, B; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Dalmau, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L S; Di Ciaccio, Lucia; Di Simone, A; Doroba, K; Drees, J; Dris, M; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J A; Gandelman, M; García, C; Gavillet, P; Gazis, E N; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Hansen, J; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Hultqvist, K; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Johansson, P D; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E C; Kernel, G; Kersevan, Borut P; Kiiskinen, A P; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kuznetsov, O; Krumshtein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Meyer, W T; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L M; Murray, W; Muryn, B; Myatt, Gerald; Myklebust, T; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V F; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Pukhaeva, N; Pullia, Antonio; Rames, J; Ramler, L; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Savoy-Navarro, A; Schwickerath, U; Segar, A; Sekulin, R L; Siebel, M; Sissakian, A N; Smadja, G; Smirnova, O G; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Taffard, A C; Tegenfeldt, F; Timmermans, J; Tkatchev, L G; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I B; Vegni, G; Veloso, F; Venus, W A; Verbeure, F; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O P; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zinchenko, A I; Zupan, M

    2003-01-01

    eta_c(2980) production in gammagamma interactions has been detected via its decays into K0_sK+-pi-+, K+K-K+K- and K+K-pi+pi- in the data taken with the DELPHI detector at LEP1 and LEP2 energies. The two-photon radiative width averaged over all observed decay channels is Gamma_gammagamma = 13.9+-2.0(stat.)+-1.4(syst.)+-2.7(BR)keV. No direct decay channel eta_c -> pi+pi-pi+pi- has been observed. An upper limit Gamma_gammagamma<5.5keV at 95% confidence level has been evaluated for this decay mode.

  13. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Carrington, P. J. [Department of Electronic and Electrical Engineering, University College London, London (United Kingdom); Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  14. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    Science.gov (United States)

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium.

  15. Two-photon spin-polarization spectroscopy in silicon-doped GaAs.

    Science.gov (United States)

    Miah, M Idrish

    2009-05-14

    We generate spin-polarized electrons in bulk GaAs using circularly polarized two-photon pumping with excess photon energy (DeltaE) and detect them by probing the spin-dependent transmission of the sample. The spin polarization of conduction band electrons is measured and is found to be strongly dependent on DeltaE. The initial polarization, pumped with DeltaE=100 meV, at liquid helium temperature is estimated to be approximately 49.5%, which is very close to the theoretical value (50%) permitted by the optical selection rules governing transitions from heavy-hole and light-hole states to conduction band states in a bulk sample. However, the polarization pumped with larger DeltaE decreases rapidly because of the exciting carriers from the split-off band.

  16. Design of two-photon molecular tandem architectures for solar cells by ab initio theory

    DEFF Research Database (Denmark)

    Ørnsø, Kristian Baruël; García Lastra, Juan Maria; De La Torre, Gema

    2015-01-01

    An extensive database of spectroscopic properties of molecules from ab initio calculations is used to design molecular complexes for use in tandem solar cells that convert two photons into a single electron–hole pair, thereby increasing the output voltage while covering a wider spectral range...... of the structural and energetic properties of several thousand porphyrin dyes. The third design is a molecular analogy of the intermediate band solar cell, and involves a single dye molecule with strong intersystem crossing to ensure a long lifetime of the intermediate state. Based on the calculated energy levels...... and molecular orbitals, energy diagrams are presented for the individual steps in the operation of such tandem solar cells. We find that theoretical open circuit voltages of up to 1.8 V can be achieved using these tandem designs. Questions about the practical implementation of prototypical devices...

  17. Leptonic two-photon events measured with L3 at the Large Electron Positron Collider (LEP)

    CERN Document Server

    Dehmelt, Klaus

    2006-01-01

    Virtual photons can fluctuate into diverse final states and among other processes, such fluctuations can yield muon-pairs. The fluctuation is a statistical process and can be described in terms of structure functions for photons. Apart from supplying another test of QED, purely leptonic processes provide a calibration fro the hadronic processes. We report on a measurement of dimuon events with single-tagged two-photon events from the LEP experiment L3, at c.m.s. energies between 189 GeV and 206 GeV, with an integrated luminosity of $\\mathcal{L}$ = 600 pb$^{-1}$. An overview of the fundamental physical processes, the detector and the anaytical tools, used for measuring dimuon events, and a discussion of the structure of dimuon events will be presented.

  18. Two-Photon Polymerization lithography for three-dimensional micro polymer parts manufacturing evaluation

    DEFF Research Database (Denmark)

    Davoudinejad, Ali; Malureanu, Radu; Palima, Darwin

    2017-01-01

    Two-photon polymerization (2PP) technique is one of the common techniques to realize the fabrication of high-quality 3D microstructures. The combination between the laser power, the printing strategy, and the printed feature size are not completely assessed. This study characterizes the additive...... manufacturing processes by Direct Laser Writing (DLW) for fabrication of 3D microstructures. The printing samples were selected from a certified calibrated set with different sizes consisting of five boxes ranging from 8 μm to 200 μm. The laser power was selected as a variable parameter in order to find out...... the effect of various powers in printing size and strategy. Six different powers were selected from 0.6 mW to 1.6 mW for each set of the structure. The results show the importance of choosing the right power value, otherwise the structures would be burned for too high power or not completely polymerised...

  19. Design and performance of an ultra-flexible two-photon microscope for in vivo research

    Science.gov (United States)

    Mayrhofer, Johannes M.; Haiss, Florent; Haenni, Dominik; Weber, Stefan; Zuend, Marc; Barrett, Matthew J. P.; Ferrari, Kim David; Maechler, Philipp; Saab, Aiman S.; Stobart, Jillian L.; Wyss, Matthias T.; Johannssen, Helge; Osswald, Harald; Palmer, Lucy M.; Revol, Vincent; Schuh, Claus-Dieter; Urban, Claus; Hall, Andrew; Larkum, Matthew E.; Rutz-Innerhofer, Edith; Zeilhofer, Hanns Ulrich; Ziegler, Urs; Weber, Bruno

    2015-01-01

    We present a cost-effective in vivo two-photon microscope with a highly flexible frontend for in vivo research. Our design ensures fast and reproducible access to the area of interest, including rotation of imaging plane, and maximizes space for auxiliary experimental equipment in the vicinity of the animal. Mechanical flexibility is achieved with large motorized linear stages that move the objective in the X, Y, and Z directions up to 130 mm. 360° rotation of the frontend (rotational freedom for one axis) is achieved with the combination of a motorized high precision bearing and gearing. Additionally, the modular design of the frontend, based on commercially available optomechanical parts, allows straightforward updates to future scanning technologies. The design exceeds the mobility of previous movable microscope designs while maintaining high optical performance. PMID:26600989

  20. Inclusive $D^{*\\pm}$ production in two-photon collisions at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Carr-Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, L; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdari, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, A; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang Zhao Min; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zilizi, G; Zimmermann, B; Zöller, M

    2002-01-01

    Inclusive D*/sup +or-/ production in two-photon collisions is studied with the L3 detector at LEP, using 683 pb/sup -1/ of data collected at centre-of-mass energies from 183 to 209 GeV. Differential cross sections are determined as functions of the transverse momentum and pseudorapidity of the D*/sup +or-/ mesons in the kinematic region 1 GeV

  1. f$_1$(1285) Formation in Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Buijs, A.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; van Dierendonck, D.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duinker, P.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

    2002-01-01

    The $\\eta \\pi^+ \\pi^-$ final state in two-photon collisions is studied with the L3 detector at LEP, at centre-of-mass energies from 183 to 209~GeV with an integrated luminosity of 664.6~pb$^{-1}$. The f$_1$(1285) meson is observed and the $Q^2$ dependence of its production is compared to different form factor models. The $\\gamma\\gamma$-coupling parameter $\\tilde\\Gamma_{\\gamma\\gamma}$ is found to be $3.5 \\pm 0.6\\,(stat.) \\pm 0.5\\,(sys.)$~keV. The branching fraction $\\Gamma\\bigl({\\rm f}_1(1285)\\rightarrow{\\rm a}_0\\pi\\bigr) / \\Gamma\\bigl({\\rm f}_1(1285)\\rightarrow\\eta\\pi\\pi\\bigr)$ is also measured.

  2. Search for a two-photon exchange contribution to inclusive deep-inelastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Airapetian, A. [Physikalisches Institut, Universitaet Giessen, 35392 Giessen (Germany); Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Akopov, N. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Akopov, Z. [DESY, 22603 Hamburg (Germany); Aschenauer, E.C. [DESY, 15738 Zeuthen (Germany); Augustyniak, W. [Andrzej Soltan Institute for Nuclear Studies, 00-689 Warsaw (Poland); Avakian, R.; Avetissian, A. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Avetisyan, E. [DESY, 22603 Hamburg (Germany); Ball, B. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Belostotski, S. [Petersburg Nuclear Physics Institute, Gatchina, Leningrad region 188300 (Russian Federation); Bianchi, N. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, 00044 Frascati (Italy); Blok, H.P. [National Institute for Subatomic Physics (Nikhef), 1009 DB Amsterdam (Netherlands); Department of Physics, VU University, 1081 HV Amsterdam (Netherlands); Boettcher, H. [DESY, 15738 Zeuthen (Germany); Bonomo, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara and Dipartimento di Fisica, Universita di Ferrara, 44100 Ferrara (Italy); Borissov, A. [DESY, 22603 Hamburg (Germany); Bowles, J. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Bryzgalov, V. [Institute for High Energy Physics, Protvino, Moscow region 142281 (Russian Federation); Burns, J. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Capitani, G.P. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, 00044 Frascati (Italy); Cisbani, E. [Istituto Nazionale di Fisica Nucleare, Sezione Roma 1, Gruppo Sanita and Physics Laboratory, Istituto Superiore di Sanita, 00161 Roma (Italy)

    2010-01-04

    The transverse-target single-spin asymmetry for inclusive deep-inelastic scattering with effectively unpolarized electron and positron beams off a transversely polarized hydrogen target was measured, with the goal of searching for a two-photon exchange signal in the kinematic range 0.0071GeV{sup 2} and Q{sup 2}<1GeV{sup 2}, and for both electron and positron beams, the asymmetries are found to be consistent with zero within statistical and systematic uncertainties, which are of order 10{sup -3} for the asymmetries integrated over x{sub B}.

  3. Study of KS0 pair production in single-tag two-photon collisions

    Science.gov (United States)

    Masuda, M.; Uehara, S.; Watanabe, Y.; Adachi, I.; Ahn, J. K.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bansal, V.; Behera, P.; Berger, M.; Bhardwaj, V.; Bhuyan, B.; Biswal, J.; Bondar, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Červenkov, D.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, Y.; Choudhury, S.; Cinabro, D.; Czank, T.; Dash, N.; Di Carlo, S.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Garg, R.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gelb, M.; Giri, A.; Goldenzweig, P.; Guido, E.; Haba, J.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W.-S.; Iijima, T.; Inami, K.; Inguglia, G.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Iwasaki, Y.; Jacobs, W. W.; Jaegle, I.; Jin, Y.; Joo, K. K.; Julius, T.; Kang, K. H.; Karyan, G.; Kawasaki, T.; Kichimi, H.; Kiesling, C.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kim, K. T.; Kim, S. H.; Kodyš, P.; Kotchetkov, D.; Križan, P.; Kroeger, R.; Krokovny, P.; Kulasiri, R.; Kuzmin, A.; Kwon, Y.-J.; Lee, I. S.; Lee, S. C.; Li, L. K.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Matsuda, T.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Moon, H. K.; Mori, T.; Mussa, R.; Nakao, M.; Nakazawa, H.; Nanut, T.; Nath, K. J.; Natkaniec, Z.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Okuno, S.; Ono, H.; Onuki, Y.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Park, H.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Ritter, M.; Rostomyan, A.; Russo, G.; Sakai, Y.; Salehi, M.; Sandilya, S.; Santelj, L.; Sanuki, T.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seidl, R.; Seino, Y.; Senyo, K.; Seon, O.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T.-A.; Shimizu, N.; Shiu, J.-G.; Shwartz, B.; Sokolov, A.; Solovieva, E.; Starič, M.; Strube, J. F.; Sumihama, M.; Sumiyoshi, T.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Teramoto, Y.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Van Hulse, C.; Varner, G.; Vinokurova, A.; Vorobyev, V.; Vossen, A.; Wang, B.; Wang, C. H.; Wang, M.-Z.; Wang, P.; Wang, X. L.; Watanabe, M.; Widmann, E.; Won, E.; Ye, H.; Yuan, C. Z.; Yusa, Y.; Zakharov, S.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.; Belle Collaboration

    2018-03-01

    We report a measurement of the cross section for KS0 pair production in single-tag two-photon collisions, γ*γ →KS0KS0, for Q2 up to 30 GeV2 , where Q2 is the negative of the invariant mass squared of the tagged photon. The measurement covers the kinematic range 1.0 GeV total energy and kaon scattering angle, respectively, in the γ*γ center-of-mass system. These results are based on a data sample of 759 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. For the first time, the transition form factor of the f2'(1525 ) meson is measured separately for the helicity-0, -1, and -2 components and also compared with theoretical calculations. We have derived the cross section for the process for W total.

  4. Recent results on the proton. Two photon exchange and the radius puzzle

    Energy Technology Data Exchange (ETDEWEB)

    Bernauer, Jan [Massachusetts Institute of Technology, Cambridge (United States)

    2015-07-01

    The proton form factors and radii are in the limelight of recent and ongoing experimental and theoretical efforts, mainly driven by two anomalies. On the one hand, precise determinations of the form factor ratio with experiments using polarization differ from Rosenbluth-type extractions. The discrepancy is attributed to two-photon exchange contributions to the scattering process. Three modern experiments, at VEPP-3, Jefferson Lab and DESY (OLYMPUS), aim to measure this effect directly. On the other hand, a measurement of the Lamb shift in muonic hydrogen atoms gives a result 10 times more precise, but 7 sigma smaller than determinations from elastic scattering and electronic hydrogen spectroscopy. So far, this discrepancy is not understood. In the talk, I present the latest results and the state of research on both fronts.

  5. Singlet oxygen-mediated protein oxidation

    DEFF Research Database (Denmark)

    Wright, Adam; Bubb, William A; Hawkins, Clare Louise

    2002-01-01

    Singlet oxygen (1O2) is generated by a number of enzymes as well as by UV or visible light in the presence of a sensitizer and has been proposed as a damaging agent in a number of pathologies including cataract, sunburn, and skin cancers. Proteins, and Cys, Met, Trp, Tyr and His side chains in pa...

  6. Recycling and imaging of nuclear singlet hyperpolarization

    DEFF Research Database (Denmark)

    Pileio, Giuseppe; Bowen, Sean; Laustsen, Christoffer

    2013-01-01

    observation of the same batch of polarized nuclei over a period of 30 min and more. We report a recycling protocol in which the enhanced nuclear polarization achieved by dissolution-DNP is observed with full intensity and then returned to singlet order. MRI experiments may be run on a portion of the available...

  7. Two-Photon Exchange Effects in Elastic Electron-Proton Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Myriam James [Argonne National Lab. (ANL), Argonne, IL (United States)

    2013-08-01

    Two methods, Rosenbluth separation and polarization transfer, can be used to extract the proton form factor ratio μp GEp/GMp, but they do not yield the same results. It is thought that the disagreement is due to two photon exchange corrections to the differential cross sections. High precision proton Rosenbluth extractions were carried out at 102 kinematics points spanning 16 values of momentum transfer Q2, from 0.40 to 5.76 GeV2. Reduced cross sections were found to 1.1% or better for Q2 less than 3 GeV2 increasing to 4% at 5.76 GeV2 The form factor ratios were determined to 1:5-3% for Q2 < 1.5 GeV2, increasing to 9% by 3 GeV2 and rapidly above. Our data agrees with prior Rosenbluth, improving upon it the 1.0 - 2.0 GeV2 range to conclusively show a separation from polarization transfer where it had not been certain before. In addition, reduced cross sections at each Q2 were tested for nonlinearity in the angular variable. Such a departure from linearity would be a signature of two photon exchange effects, and prior data had not been sufficiently precise to show nonzero curvature. Our data begins to hint at negative curvature but does not yet show a significant departure from zero.

  8. Solution-dispersible Au nanocube dimers with greatly enhanced two-photon luminescence and SERS

    Science.gov (United States)

    Liu, Xiao-Li; Liang, Shan; Nan, Fan; Yang, Zhong-Jian; Yu, Xue-Feng; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2013-05-01

    We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS.We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01170d

  9. Automated filtering of intrinsic movement artifacts during two-photon intravital microscopy.

    Directory of Open Access Journals (Sweden)

    Denis Soulet

    Full Text Available In vivo imaging using two-photon microscopy is an essential tool to explore the dynamic of physiological events deep within biological tissues for short or extended periods of time. The new capabilities offered by this technology (e.g. high tissue penetrance, low toxicity have opened a whole new era of investigations in modern biomedical research. However, the potential of using this promising technique in tissues of living animals is greatly limited by the intrinsic irregular movements that are caused by cardiac and respiratory cycles and muscular and vascular tone. Here, we show real-time imaging of the brain, spinal cord, sciatic nerve and myenteric plexus of living mice using a new automated program, named Intravital_Microscopy_Toolbox, that removes frames corrupted with motion artifacts from time-lapse videos. Our approach involves generating a dissimilarity score against precalculated reference frames in a specific reference channel, thus allowing the gating of distorted, out-of-focus or translated frames. Since the algorithm detects the uneven peaks of image distortion caused by irregular animal movements, the macro allows a fast and efficient filtering of the image sequence. In addition, extra features have been implemented in the macro, such as XY registration, channel subtraction, extended field of view with maximum intensity projection, noise reduction with average intensity projections, and automated timestamp and scale bar overlay. Thus, the Intravital_Microscopy_Toolbox macro for ImageJ provides convenient tools for biologists who are performing in vivo two-photon imaging in tissues prone to motion artifacts.

  10. Two-Photon Microscopy Analysis of Gold Nanoparticle Uptake in 3D Cell Spheroids.

    Directory of Open Access Journals (Sweden)

    Tushar D Rane

    Full Text Available Nanomaterials can be synthesized from a wide range of material systems in numerous morphologies, creating an extremely diverse portfolio. As result of this tunability, these materials are emerging as a new class of nanotherapeutics and imaging agents. One particularly interesting nanomaterial is the gold nanoparticle. Due to its inherent biocompatibility and tunable photothermal behavior, it has made a rapid transition from the lab setting to in vivo testing. In most nanotherapeutic applications, the efficacy of the agent is directly related to the target of interest. However, the optimization of the AuNP size and shape for efficacy in vitro, prior to testing in in vivo models of a disease, has been largely limited to two dimensional monolayers of cells. Two dimensional cell cultures are unable to reproduce conditions experienced by AuNP in the body. In this article, we systematically investigate the effect of different properties of AuNP on the penetration depth into 3D cell spheroids using two-photon microscopy. The 3D spheroids are formed from the HCT116 cell line, a colorectal carcinoma cell line. In addition to studying different sizes and shapes of AuNPs, we also study the effect of an oligo surface chemistry. There is a significant difference between AuNP uptake profiles in the 2D monolayers of cells as compared to the 3D cell spheroids. Additionally, the range of sizes and shapes studied here also exhibit marked differences in uptake penetration depth and efficacy. Finally, our results demonstrate that two-photon microscopy enables quantitative AuNP localization and concentration data to be obtained at the single spheroid level without fluorescent labeling of the AuNP, thus, providing a viable technique for large scale screening of AuNP properties in 3D cell spheroids as compared to tedious and time consuming techniques like electron microscopy.

  11. Two-photon physics and online beam monitoring using the DELPHI detector at LEP

    International Nuclear Information System (INIS)

    Bjarne, J.

    1994-01-01

    This thesis is based on work done during 1989-1993 using the DELPHI detector at LEP, which is summarized in five articles. It consists of three main parts. The first part describes the Very Small Angle Tagger (VSAT), which is a sub-detector of the DELPHI detector at LEP. It consists of four silicon-tungsten electromagnetic calorimeter modules having a silicon strip planes for position determination. The modules are placed adjacent to the beam pipe, at ±7.7 m from the interaction point and after superconducting quadrupole magnets, allowing the detection of electrons in a polar angle range of 4 to 13 mrad. The second part is devoted to two-photon physics at DELPHI, with strong emphasis on a VSAT single-tagged event analysis. Here is shown, for the first time, evidence of hard scattering processes in single-tagged two-photon collisions. A QCD Resolved Photon Contribution (QCD-RPC) model is introduced. Data is then seen to be well described by a full VDM+(QCD-RPC) model. Different parton density functions are compared with data. The third part first describes the system for online monitoring of LEP beam background and luminosity at the DELPHI interaction point. Details are given of contributing sub-detector signals and program structure. Then follows a description of the VSAT online monitoring program (VSAT-MONITOR). A good agreement is found between the VSAT-MONITOR estimates of luminosity and beam spot and those of other detectors. Finally, results are presented of VSAT measurements of a LEP beam separation scan. 75 refs, figs

  12. A two-photon fluorescent probe with a large turn-on signal for imaging hydrogen sulfide in living tissues

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Kaibo [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Lin, Weiying, E-mail: weiyinglin2013@163.com [Institute of Fluorescent Probes for Biological Imaging, University of Jinan, Jinan, Shandong 250022 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Tan, Li; Cheng, Dan [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China)

    2015-01-01

    Highlights: • A two-photon fluorescent probe for sensing H{sub 2}S was developed. • The probe shows a large turn on signal (120-fold enhancement). • The probe is suitable for fluorescence imaging of H{sub 2}S in living cells and tissues. • The probe was capable of detecting H{sub 2}S up to 170 μm depth in live tissues. - Abstract: A two-photon fluorescence turn-on H{sub 2}S probe GCTPOC–H{sub 2}S based on a two-photon platform with a large cross-section, GCTPOC, and a sensitive H{sub 2}S recognition site, dinitrophenyl ether was constructed. The probe GCTPOC–H{sub 2}S exhibits desirable properties such as high sensitivity, high selectivity, functioning well at physiological pH and low cytotoxicity. In particular, the probe shows a 120-fold enhancement in the presence of Na{sub 2}S (500 μM), which is larger than the reported two-photon fluorescent H{sub 2}S probes. The large fluorescence enhancement of the two-photon probe GCTPOC–H{sub 2}S renders it attractive for imaging H{sub 2}S in living tissues with deep tissue penetration. Significantly, we have demonstrated that the probe GCTPOC–H{sub 2}S is suitable for fluorescence imaging of H{sub 2}S in living tissues with deep penetration by using two-photon microscopy. The further application of the two-photon probe for the investigation of biological functions and pathological roles of H{sub 2}S in living systems is under progress.

  13. Doppler-free two-photon spectroscopy of Yb atoms and efficient generation of a cascade of two photons at 611.3 nm and 555.8 nm

    International Nuclear Information System (INIS)

    Song, Minsoo; Yoon, Duseong; Yoon, Taihyun

    2011-01-01

    We performed high-resolution Doppler-free two-photon spectroscopy of Yb atoms in an effusive atomic beam and generated a cascade of two photons at 611.3 nm (idler) and 555.8 nm (signal) with a narrow bandwidth of 37 MHz. Efficient population transfer from the ground state (6s 2 1 S 0 ) to the upper state (6s7s 1 S 0 ), where direct transition at 291.1 nm is dipole forbidden, was achieved through a resonant two-photon excitation enhanced by the electromagnetically-induced transparency mediated by the intermediate state (6s6p 1 P 1 ). From the upper state, a cascade of two photons in sequence was emitted via the spin triplet state (6s 2 3 P 1 ). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields explain quantitatively the experimental results for the dependences of the idler and the signal beam intensities on the various parameters of the driving fields. We report on the generation of a cascade of two photons with fluxes at the level of a few times 10 6 photons/s detected at a solid angle of 0.01 sr.

  14. Doppler-free two-photon spectroscopy of Yb atoms and efficient generation of a cascade of two photons at 611.3 nm and 555.8 nm

    Energy Technology Data Exchange (ETDEWEB)

    Song, Minsoo; Yoon, Duseong; Yoon, Taihyun [Korea University, Seoul (Korea, Republic of)

    2011-10-15

    We performed high-resolution Doppler-free two-photon spectroscopy of Yb atoms in an effusive atomic beam and generated a cascade of two photons at 611.3 nm (idler) and 555.8 nm (signal) with a narrow bandwidth of 37 MHz. Efficient population transfer from the ground state (6s{sup 2} {sup 1}S{sub 0}) to the upper state (6s7s {sup 1}S{sub 0}), where direct transition at 291.1 nm is dipole forbidden, was achieved through a resonant two-photon excitation enhanced by the electromagnetically-induced transparency mediated by the intermediate state (6s6p {sup 1}P{sub 1}). From the upper state, a cascade of two photons in sequence was emitted via the spin triplet state (6s{sup 2} {sup 3}P{sub 1}). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields explain quantitatively the experimental results for the dependences of the idler and the signal beam intensities on the various parameters of the driving fields. We report on the generation of a cascade of two photons with fluxes at the level of a few times 10{sup 6} photons/s detected at a solid angle of 0.01 sr.

  15. Antiaromatic bisindeno-[n]thienoacenes with small singlet biradical characters: Syntheses, structures and chain length dependent physical properties

    KAUST Repository

    Shi, Xueliang

    2014-01-01

    Recent studies demonstrated that aromaticity and biradical character play important roles in determining the ground-state structures and physical properties of quinoidal polycyclic hydrocarbons and oligothiophenes, a kind of molecular materials showing promising applications for organic electronics, photonics and spintronics. In this work, we designed and synthesized a new type of hybrid system, the so-called bisindeno-[n]thienoacenes (n = 1-4), by annulation of quinoidal fused α-oligothiophenes with two indene units. The obtained molecules can be regarded as antiaromatic systems containing 4n π electrons with small singlet biradical character (y0). Their ground-state geometry and electronic structures were studied by X-ray crystallographic analysis, NMR, ESR and Raman spectroscopy, assisted by density functional theory calculations. With extension of the chain length, the molecules showed a gradual increase of the singlet biradical character accompanied by decreased antiaromaticity, finally leading to a highly reactive bisindeno[4]thienoacene (S4-TIPS) which has a singlet biradical ground state (y0= 0.202). Their optical and electronic properties in the neutral and charged states were systematically investigated by one-photon absorption, two-photon absorption, transient absorption spectroscopy, cyclic voltammetry and spectroelectrochemistry, which could be correlated to the chain length dependent antiaromaticity and biradical character. Our detailed studies revealed a clear structure-aromaticity-biradical character-physical properties-reactivity relationship, which is of importance for tailored material design in the future. This journal is

  16. Validation of quantitative structure-activity relationship (QSAR) model for photosensitizer activity prediction.

    Science.gov (United States)

    Frimayanti, Neni; Yam, Mun Li; Lee, Hong Boon; Othman, Rozana; Zain, Sharifuddin M; Rahman, Noorsaadah Abd

    2011-01-01

    Photodynamic therapy is a relatively new treatment method for cancer which utilizes a combination of oxygen, a photosensitizer and light to generate reactive singlet oxygen that eradicates tumors via direct cell-killing, vasculature damage and engagement of the immune system. Most of photosensitizers that are in clinical and pre-clinical assessments, or those that are already approved for clinical use, are mainly based on cyclic tetrapyrroles. In an attempt to discover new effective photosensitizers, we report the use of the quantitative structure-activity relationship (QSAR) method to develop a model that could correlate the structural features of cyclic tetrapyrrole-based compounds with their photodynamic therapy (PDT) activity. In this study, a set of 36 porphyrin derivatives was used in the model development where 24 of these compounds were in the training set and the remaining 12 compounds were in the test set. The development of the QSAR model involved the use of the multiple linear regression analysis (MLRA) method. Based on the method, r(2) value, r(2) (CV) value and r(2) prediction value of 0.87, 0.71 and 0.70 were obtained. The QSAR model was also employed to predict the experimental compounds in an external test set. This external test set comprises 20 porphyrin-based compounds with experimental IC(50) values ranging from 0.39 μM to 7.04 μM. Thus the model showed good correlative and predictive ability, with a predictive correlation coefficient (r(2) prediction for external test set) of 0.52. The developed QSAR model was used to discover some compounds as new lead photosensitizers from this external test set.

  17. Validation of Quantitative Structure-Activity Relationship (QSAR) Model for Photosensitizer Activity Prediction

    Science.gov (United States)

    Frimayanti, Neni; Yam, Mun Li; Lee, Hong Boon; Othman, Rozana; Zain, Sharifuddin M.; Rahman, Noorsaadah Abd.

    2011-01-01

    Photodynamic therapy is a relatively new treatment method for cancer which utilizes a combination of oxygen, a photosensitizer and light to generate reactive singlet oxygen that eradicates tumors via direct cell-killing, vasculature damage and engagement of the immune system. Most of photosensitizers that are in clinical and pre-clinical assessments, or those that are already approved for clinical use, are mainly based on cyclic tetrapyrroles. In an attempt to discover new effective photosensitizers, we report the use of the quantitative structure-activity relationship (QSAR) method to develop a model that could correlate the structural features of cyclic tetrapyrrole-based compounds with their photodynamic therapy (PDT) activity. In this study, a set of 36 porphyrin derivatives was used in the model development where 24 of these compounds were in the training set and the remaining 12 compounds were in the test set. The development of the QSAR model involved the use of the multiple linear regression analysis (MLRA) method. Based on the method, r2 value, r2 (CV) value and r2 prediction value of 0.87, 0.71 and 0.70 were obtained. The QSAR model was also employed to predict the experimental compounds in an external test set. This external test set comprises 20 porphyrin-based compounds with experimental IC50 values ranging from 0.39 μM to 7.04 μM. Thus the model showed good correlative and predictive ability, with a predictive correlation coefficient (r2 prediction for external test set) of 0.52. The developed QSAR model was used to discover some compounds as new lead photosensitizers from this external test set. PMID:22272096

  18. New Photosensitizers for Photodynamic Therapy in Gastroenterology

    Directory of Open Access Journals (Sweden)

    SG Bown

    1999-01-01

    Full Text Available Most applications of photodynamic therapy (PDT in gastroenterology to date have used porfimer sodium as the photosensitizing agent. For destroying small lesions in the wall of the gastrointestinal tract in inoperable patients, it has proved to be most effective, but attempts to achieve circumferential mucosal ablation, as in the treatment of Barrett’s esophagus, have led to a high incidence of strictures, and all patients have cutaneous photosensitivity, which can last up to three months. Two new photosensitizers are of particular interest to gastroenterologists. PDT with metatetrahydroxyphenyl chlorin produces a similar biological effect as PDT with porfimer sodium, but the light doses required are much smaller, and cutaneous photosensitivity lasts only two to three weeks. Further, it can be used with percutaneous light delivery to destroy localized pancreatic cancers. The photosensitizing agent 5-amino levulinic acid, converted in vivo into the photoactive derivative protoporphyrin IX, sensitizes the mucosa much more than the underlying layers. This makes it feasible to destroy areas of abnormal mucosa without damaging the underlying muscle and is, therefore, better for treating Barrett’s esophagus. Detailed clinical studies are required to establish the real role of PDT with the use of these and other new photosensitizers.

  19. Ag@Aggregation-induced emission dye core/shell nanostructures with enhanced one- and two-photon fluorescence

    Science.gov (United States)

    Wang, Cheng; Li, Yang; Xu, Qiujin; Luo, Liang

    2017-10-01

    Combining plasmonic nanostructures with two-photon fluorescence materials is a promising way to significantly enhance two-photon fluorescence. Ag@1,4-bis(2-cyano-2-phenylethenyl) benzene (BCPEB) core/shell nanostructures were fabricated by simply incubating the isolated Ag nanoparticles with BCPEB microrods in ethanol. BCPEB was chosen as the fluorescent organic molecule owing to the aggregation-induced-emission (AIE) nature which would reduce the emission loss as being practically applied in solid phase. By utilizing the match of the extinction spectrum of Ag nanoparticles and BCPEB's absorption band, the target Ag@BCPEB core/shell nanostructures showed an enhanced one-photon (12×) fluorescence, integrating with SERS signal as well. Moreover, the resultant second harmonic generation of Ag nanoparticles under two-photon excitation also well matched with the absorption band of BCPEB, and significant enhanced two-photon (17×) fluorescence was obtained. The confocal images of NIH-3T3 cells with these nanostructures under one- and two-photon excitation showed good contrast and brightness for bio-imaging.

  20. Two-Photon-Induced Isomerization of Spiropyran/Merocyanine at the Air/Water Interface Probed by Second Harmonic Generation.

    Science.gov (United States)

    Lin, Lu; Zhang, Zhen; Lu, Zhou; Guo, Yuan; Liu, Minghua

    2016-10-13

    Photochromic molecules often exhibit switchable hyperpolarizabilities upon photoisomerization between two molecular states and can be widely applied in nonlinear optical materials. Photoisomerization can occur through either one-photon or two-photon processes. Two-photon-induced isomerization has several advantages over one-photon process but has not been fully explored. In the present study, we have used second harmonic generation to investigate the two-photon-induced isomerization between spiropyran and merocyanine at the air/water interface. We show that spiropyran and merocyanine can be converted into each other reversibly with 780-nm laser-beam irradiation through two-photon processes. We also investigated the isomerization rates under various incident laser powers. Quantitative analysis revealed that the isomerization rates of spiropyran and merocyanine depend differently on the laser power. We attribute the difference to the distinct molecular structures of spiropyran and merocyanine. At the interface, nonplanar spiropyran molecules exist mainly as monomers, whereas planar merocyanine molecules form aggregates. Upon aggregation, steric hindrance effects and excitonic coupling efficiently arrest the photoisomerization of merocyanine. This work provides an in-depth understanding of two-photon-induced isomerization at the interface, which is beneficial for designing and controlling optical thin-film materials.

  1. Efficiency factors of singlet oxygen generation from core-modified expanded porphyrin: tetrathiarubyrin in ethanol

    CERN Document Server

    Ha, J H; Kim, Y R; Jung, G Y; Lee, Y H; Shin, K

    2001-01-01

    The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin have been investigated to elucidate the possibility of its use as a photodynamic therapy (PDT) photosensitizer by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were affected by various molecular aspects, such as extended pi conjugation, structural distortion, and internal heavy atom. The steady-state electronic absorption spectrum was red-shifted due to the extended pi-conjugation, and the spin orbital coupling was enhanced by the structural distortion and the internal heavy atom effect. As a result of the enhanced spin orbital coupling, the triplet quantum yield increased to 0.90 +- 0.10 and the triplet state lifetime was shortened to 7.0 +- 1.2 mu s. Since the triplet state decays at a relatively faster rate, the efficiency of the oxygen quenching of the triplet state decreases. The singlet oxygen quantum yield was estimated to be 0.52 +- 0.02, which is somewhat lower t...

  2. Singlet oxygen explicit dosimetry to predict local tumor control for HPPH-mediated photodynamic therapy

    Science.gov (United States)

    Penjweini, Rozhin; Kim, Michele M.; Ong, Yi Hong; Zhu, Timothy C.

    2017-02-01

    This preclinical study examines four dosimetric quantities (light fluence, photosensitizer photobleaching ratio, PDT dose, and reacted singlet oxygen ([1O2]rx)) to predict local control rate (LCR) for 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated photodynamic therapy (PDT). Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated with different in-air fluences (135, 250 and 350 J/cm2) and in-air fluence rates (50, 75 and 150 mW/cm2) at 0.25 mg/kg HPPH and a drug-light interval of 24 hours using a 1 cm diameter collimated laser beam at 665 nm wavelength. A macroscopic model was used to calculate ([1O2]rx)) based on in vivo explicit dosimetry of the initial tissue oxygenation, photosensitizer concentration, and tissue optical properties. PDT dose was defined as a temporal integral of drug concentration and fluence rate (φ) at a 3 mm tumor depth. Light fluence rate was calculated throughout the treatment volume based on Monte-Carlo simulation and measured tissue optical properties. The tumor volume of each mouse was tracked for 30 days after PDT and Kaplan-Meier analyses for LCR were performed based on a tumor volume <=100 mm3, for four dose metrics: fluence, HPPH photobleaching rate, PDT dose, and ([1O2]rx)). The results of this study showed that ([1O2]rx)) is the best dosimetric quantity that can predict tumor response and correlate with LCR.

  3. Measurement of exclusive two-photon processes with dilepton final states in pp collisions at the LHC

    CERN Document Server

    Forthomme, Laurent

    The unification of the electromagnetic and weak forces is a cornerstone of the standard theory of elementary particles and fundamental interactions. At the Large Hadron Collider the processes of pair production via fusion of two exchanged photons provide a unique laboratory both for testing the standard theory and for search of new phenomena in high-energy physics. In this thesis such a two-photon exclusive pair production in pp collisions has been studied experimentally, at two centre of mass energies using the data collected with the CMS experiment during LHC's Run-1. Thanks to large, effective photon fluxes and the outstanding performance of the CMS apparatus clean two-photon signal samples could be extracted. The novel track-based exclusivity selection was instrumental for making successful measurements in an extremely demanding LHC environment. In particular, the "reference" two-photon production of lepton pairs has been measured and investigated in detail, including extended phenomenological studies. A ...

  4. In vivo two-photon fluorescence imaging with Cr:forsterite lasers using transgenic lines tagged by HcRed

    Science.gov (United States)

    Tsai, Tsung-Han; Chen, Szu-Yu; Tai, Shih-Peng; Lin, Cheng-Yung; Tsai, Huai-Jen; Sun, Chi-Kuang

    2005-03-01

    Transgenic lines carrying a specific tissue tagged by green-fluorescence-protein (GFP) have been a powerful tool to developmental biology because they encapsulate the expression of endogenous genes. Traditionally with two-photon fluorescence microscopy based on a femtosecond Ti:sapphire laser (with a wavelength between 700-980nm), green fluorescence can be excited by simultaneous absorption of two photons for high-resolution three-dimensional (3D) optical imaging. However for in vivo biological applications, Ti:sapphire-laser based optical technology presents several limitations including finite penetration depth, strong on-focus cell damage, and phototoxicity. For high optical penetration and minimized photodamages, two-photon imaging based on light sources with an optical wavelength located around the biological penetration window (~1300nm) is desired, where unwanted light-tissue interactions including scattering, absorption, and photodamages can all be minimized. Previous experiments around the optical penetration window indicated inefficient green fluorescence excitation of GFP through three-photon absorption. Red fluorescence protein is thus highly desired for future non-invasive in vivo two-photon imaging. Screening from embryos injected with DNA fragment containing a heart-specific regulatory element of zebrafish cardiac myosin light chain 2 gene (cmlc2) fused with HcRed gene, we generate a zebrafish line that has strong two-photon red fluorescence expressed in cardiac cells based on a 1230nm femtosecond light source working in the biological penetration window. Combined with its nonlinearity, high penetration depth, and minimized photodamages, this method provides superb imaging capability compared with the traditional GFP based two-photon microscopy, offering deep insight into the noninvasive in vivo studies of gene expression in vertebrate embryos.

  5. One-Photon and Two-Photon Double-Slit Interferences in Spontaneous and Stimulated Parametric Down-Conversions

    OpenAIRE

    Cao, De-Zhong; Li, Zhuan; Zhai, Yan-Hua; Wang, Kaige

    2004-01-01

    We theoretically discuss one-photon and two-photon double-slit interferences for spontaneous and stimulated parametric down-conversions. We show that the two-photon sub-wavelength interference can exist in a general spontaneous parametric down-conversion (SPDC) for both type I and type II crystals. We propose an alternative way to observe sub-wavelength interference by a joint-intensity measurement which occurs for only type I crystal in a higher gain of SPDC. When a signal beam injects into ...

  6. Two-photon mass spectra produced in p-p collision at √s = 52 GeV

    International Nuclear Information System (INIS)

    Amaldi, E.; Beneventano, M.; Borgia, B.; Capone, A.; De Notaristefani, F.; Dore, U.; Ferroni, F.; Longo, E.; Luminari, L.; Pistilli, P.; Sestili, I.; Dooher, J.

    1977-01-01

    The photon-photon final state in the interaction of p-p at √s = 52 GeV has been investigated, detecting the two photons on opposite sides around 90 0 with respect to the circulating beams of the ISR. In the invariant mass spectrum derived from this configuration no structure is observed above the background. Upper limits for production of narrow resonances decaying into two photons are derived for invariant masses larger than 2.5 GeV/c 2 . (author)

  7. Study of inclusive strange-baryon production and search for pentaquarks in two-photon collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Jin, B.N.; Jindal, P.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, J.; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pieri, M.; Pioppi, M.; PirouLe, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Rembeczki, S.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, Stefan; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Vesztergombi, G.; Vetlitsky, I.; Viertel, G.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2007-01-01

    Measurements of inclusive production of the Lambda, Xi- and Xi*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections for Lambda and Xi- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, eta. The mean number of Lambda, Xi- and Xi*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4 GeV proton K0s is also presented. No evidence for production of this state is found.

  8. Measurement of Exclusive $\\rho^+ \\rho^-$ Production in High-$Q^2$ Two-Photon Collisions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, Stefan; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.

    2004-01-01

    Exclusive rho^+ rho^- production in two-photon collisions involving a single highly-virtual photon is studied with data collected at LEP at centre-of-mass energies 89 GeV rho^+ rho^- is determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, W_gg, in the kinematic region: 1.2 GeV^2 rho^0 rho^0, measured in the same kinematic region by L3, and to have similar W_gg and Q^2 dependences.

  9. Measurement of Exclusive $\\rho^{0}\\rho^{0}$ Production in Mid-Virtuality Two-Photon Interactions at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Jin, B.N.; Jindal, P.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, Stefan; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2004-01-01

    Exclusive rho^0 rho^0 production in two-photon collisions between a quasi-real and a mid-virtuality photon is studied with data collected at LEP at centre-of-mass energies 183GeV rho^0 rho^0 is determined as a function of the photon virtuality, q^2, and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 0.2GeV^2 < q^2 < 0.85GeV^2 and 1.1GeV < Wgg < 3GeV.

  10. Biomolecular imaging based on far-red fluorescent protein with a high two-photon excitation action cross section

    Science.gov (United States)

    Tsai, Tsung-Han; Lin, Cheng-Yung; Tsai, Huai-Jen; Chen, Szu-Yu; Tai, Shih-Peng; Lin, Kung-Hsuan; Sun, Chi-Kuang

    2006-04-01

    The two-photon excitation action cross section of Hc-Red fluorescent proteins (Hc-RFPs) is measured and found to be of the same order as that of enhanced green fluorescent proteins. With a 618 nm emission wavelength in the far-red region and with an excitation wavelength around 1200 nm, Hc-RPF-based two-photon fluorescence microscopy (2PFM) can offer deep penetration capability inside live samples and is ideal for in vivo gene expression study and biomolecular imaging in live objects. In vivo 2PFM of the developing heart deep inside a transgenic zebrafish embryo tagged by Hc-RFP is also successfully demonstrated.

  11. Measurement of Exclusive $\\rho^0 \\rho^0$ Production in Two-Photon Collisions at High $Q^2$ at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2003-01-01

    Exclusive rho rho production in two-photon collisions involving a single highly virtual photon is studied with data collected at LEP at centre-of-mass energies 89GeV rho rho is determined as a function of the photon virtuality, Q^2 and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 1.2GeV^2 < Q^2 < 30GeV^2 and 1.1GeV < Wgg < 3GeV.

  12. Singlet Glueballs In Klebanov-Strassler Theory

    Science.gov (United States)

    Gordeli, Ivan

    In this thesis we complete the singlet glueball sector analysis of the N = 1 super-symmetric Klebanov-Strassler gauge theory. Employing the string theory holographic approach we come up with a prediction of the spectrum of lightest glueballs in SU(N) N = 1 supersymmetric Yang-Mills theory at large N. Interestingly the spectrum of some of the glueballs is consistent with the lattice results for QCD glueballs.

  13. Magnetic properties of singlet ground state systems

    International Nuclear Information System (INIS)

    Diederix, K.M.

    1979-01-01

    Experiments are described determining the properties of a magnetic system consisting of a singlet ground state. Cu(NO 3 ) 2 .2 1/2H 2 O has been studied which is a system of S = 1/2 alternating antiferromagnetic Heisenberg chains. The static properties, spin lattice relaxation time and field-induced antiferromagnetically ordered state measurements are presented. Susceptibility and magnetic cooling measurements of other compounds are summarised. (Auth.)

  14. Singlet - oxygen therapy. 'MIT-S' apparatus

    International Nuclear Information System (INIS)

    Samosyuk, I.Z.; Chukhraev, N.V.; Pisanko, O.I.

    2003-01-01

    The described method is based on using singlet-oxygen mixture with antioxiding properties. This mixture is produced by photochemical sensibilization of air or water vapour in MIT-S apparatus. Technical parameters of MIT-S are presented. The method is used for therapy of different organs, for prophylactics, treatment and rehabilitation of a series of diseases (bronchial asthma, cardio-vascular, neurologic, sugar diabet, immune diseases)

  15. High-power generator of singlet oxygen

    Czech Academy of Sciences Publication Activity Database

    Jirásek, Vít; Čenský, Miroslav; Špalek, Otomar; Kodymová, Jarmila

    2013-01-01

    Roč. 36, č. 10 (2013), s. 1755-1763 ISSN 0930-7516 Grant - others:Laser Science and Technology Centre(IN) LASTEC/FE/RKT/54/10-11 Institutional research plan: CEZ:AV0Z10100523 Keywords : high-pressure singlet oxygen generator * spray generator * centrifugal separation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.175, year: 2013

  16. Surface photovoltage investigation of gold chains on Si(111) by two-photon photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Sebastian; Biedermann, Kerstin; Fauster, Thomas [Lehrstuhl fuer Festkoerperphysik, Universitaet Erlangen-Nuernberg, Staudtstr. 7, D-91058 Erlangen (Germany)

    2011-07-01

    We present surface photovoltage measurements on Si(111)-(7 x 7) with monoatomic gold chains. The gold coverage was varied between zero and 0.6 ML, where the Si(111)-(5 x 2)-Au reconstruction covers the surface completely. During the two-photon photoemission experiments the p- or n-doped samples were illuminated by infrared (IR, E{sub IR}=1.55 eV) and ultraviolet (UV, E{sub UV}=4.65 eV) laser pulses. For all coverages the photovoltage was determined for sample temperatures of 90 K and 300 K by variation of the IR and UV laser power. P-doped as well as n-doped Si(111) wafers show a linear dependence of the photovoltage on gold coverage. This stands in contrast to scanning tunneling spectroscopy measurements, which show a coverage-independent photovoltage over a wide coverage range for n-doped wafers. While for p-doped wafers our experimentally determined photovoltage is in agreement with previous reports, for n-doped wafers the observed values are lower than expected.

  17. Two-Photon Polymerization Metrology: Characterization Methods of Mechanisms and Microstructures

    Directory of Open Access Journals (Sweden)

    Christopher N. LaFratta

    2017-03-01

    Full Text Available The ability to create complex three-dimensional microstructures has reached an unprecedented level of sophistication in the last 15 years. For the most part, this is the result of a steady development of the additive manufacturing technique named two-photon polymerization (TPP. In a short amount of time, TPP has gone from being a microfabrication novelty employed largely by laser specialists to a useful tool in the hands of scientists and engineers working in a wide range of research fields including microfluidics. When used in combination with traditional microfabrication processes, TPP can be employed to add unique three-dimensional components to planar platforms, thus enabling the realization of lab-on-a-chip solutions otherwise impossible to create. To take full advantage of TPP, an in-depth understanding is required of the materials photochemistry and the fabricated microstructures’ mechanical and chemical properties. Thus, we review methods developed so far to investigate the underling mechanism involved during TPP and analytical methods employed to characterize TPP microstructures. Furthermore, we will discuss potential opportunities for using optofluidics and lab-on-a-chip systems for TPP metrology.

  18. Luminosity measurements and two-photon physics with the DELPHI VSAT at LEP

    International Nuclear Information System (INIS)

    Jonsson, Per M.

    1998-02-01

    This thesis describes analysis of data from the DELPHI Very Small Angle Tagger (VSAT) calorimeter at LEP1. The VSAT consists of four Silicon-Tungsten calorimeter modules symmetrically positioned 7.7 meters away from the inter-action point. It measures elastically scattered electrons and positrons, Bhabha events, within the polar angular region between 5-12 mrad. Trigger efficiency and reconstruction procedures for the energy and position measurement of VSAT data are described. Off momentum electron background and online luminosity monitoring with the VSAT are also discussed. The extraction of various beam-parameters from analysis of the impact point of Bhabha pairs reveal the ability to measure variations in beam angles with a precision of 50 microrad. The relative luminosity measurement of the VSAT with a precision level of 0.1% for the 1993-1994 Z 0 scan is also presented. Through the study of double-tag-photon events, using the VSAT for measuring the energy of both scattered electrons, the behaviour of the total hadronic two-photon cross section is for the first time investigated up to invariant masses of 35 GeV

  19. Highly efficient and two-photon excited stimulated Rayleigh-Bragg scattering in organic solutions

    Energy Technology Data Exchange (ETDEWEB)

    He, Guang S., E-mail: gshe@buffalo.edu; Prasad, Paras N. [The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States); Kannan, Ramamurthi; Tan, Loon-Seng [Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RX, Wright-Patterson AFB, Ohio 45433-7750 (United States)

    2015-07-21

    The properties of backward stimulated Rayleigh-Bragg scattering (SRBS) in three highly two-photon active AF-chromophores solutions in tetrahydrofuran (THF) have been investigated using 816-nm and 8-ns pump laser beam. The nonlinear reflectivity R, spectral structure, temporal behavior, and phase-conjugation capability of the backward SRBS output have been measured, respectively. Under the same experimental condition, the pump threshold for SRBS in three solution samples can be significantly (∼one order of magnitude) lower than that for stimulated Brillouin scattering (SBS) in the pure solvent (THF). With the optimized concentration value and at a moderate pump energy (∼1.5 mJ) level, the measured nonlinear reflectivity was R ≥ 35% for the 2 cm-long solution sample, while for the SBS from a pure solvent sample of the same length was R ≈ 4.7%. The peculiar features of very low pump threshold, no spectral shift, tolerant pump spectral linewidth requirement (≤1 cm{sup −1}), and phase-conjugation capability are favorable for those nonlinear photonics applications, such as highly efficiency phase-conjugation reflectors for high-brightness laser oscillator/amplifier systems, special imaging through turbid medium, self-adaptive remote optical sensing, as well as for optical rangefinder and lidar systems.

  20. Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Photons

    CERN Document Server

    CMS Collaboration

    2017-01-01

    A search for the associated production of dark matter with a Higgs boson which decays into two photons is presented. The search uses data from proton-proton collisions at a center-of-mass energy of $13~\\mathrm{TeV}$, collected with the CMS detector at the LHC in 2016, corresponding to an integrated luminosity of $35.9~\\mathrm{fb}^{-1}$. Results are interpreted in the context of two dark matter models: a two-Higgs-doublet-Z' model where the Z' decays to a pseudoscalar and a standard model-like Higgs Boson and a baryonic Z' simplified model. The search is performed categorizing the events based on the amount of missing transverse momentum in order to also be sensitive to hypothetical signals with small amounts of missing transverse momentum. After the final selection, no significant evidence for dark matter particle production has been observed. Two-Higgs-doublet-Z' signals with a pseudoscalar mass of $300~\\mathrm{GeV}$ are excluded at $95\\%$ of CL for Z' masses below $900~\\mathrm{GeV}$. Baryonic Z' models with...

  1. Reactive quenching of two-photon excited xenon atoms by Cl2

    International Nuclear Information System (INIS)

    Bruce, M.R.; Layne, W.B.; Meyer, E.; Keto, J.W.

    1987-01-01

    Total binary and tertiary quench rates have been measured for the reaction Xe (5p 5 6p) + Cl 2 at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with a uv laser. The time dependent fluorescence from the excited atom in the IR and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl 2 pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k 2 ∼ 10 -9 cm 3 sec -1 ) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k 3 ∼ 10 -28 cm 6 sec -1 ). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed

  2. Alignment effects in two-photon double ionization of H2 in femtosecond xuv laser pulses

    International Nuclear Information System (INIS)

    Guan Xiaoxu; Bartschat, Klaus; Schneider, Barry I.

    2011-01-01

    Triple-differential cross sections for two-photon double ionization of the aligned hydrogen molecule at the equilibrium distance are presented for a central photon energy of 30 eV. The temporal response of the laser-driven molecule is investigated by solving the time-dependent Schroedinger equation in full dimensionality using two-center elliptical coordinates and a finite-element discrete-variable-representation approach. The molecular orientation is found to have a strong effect on the emission modes of the two correlated photoelectrons. This molecular effect is most noticeable when the molecular axis and the laser polarization vector are oriented parallel to each other. For intermediate cases between the parallel and perpendicular geometries, the dominant emission modes for two-electron ejection oscillate between those for the two extreme cases. The contributions from different ionization channels are also analyzed in detail. Depending on the emission direction of the reference electron, the interference contributions from the various channels can be constructive or destructive at small alignment angles, while they always contribute constructively to the triple-differential cross sections near the perpendicular geometry.

  3. Automatic quantification of mitochondrial fragmentation from two-photon microscope images of mouse brain tissue.

    Science.gov (United States)

    Lihavainen, E; Kislin, M; Toptunov, D; Khiroug, L; Ribeiro, A S

    2015-12-01

    The morphology of mitochondria can inform about their functional state and, thus, about cell vitality. For example, fragmentation of the mitochondrial network is associated with many diseases. Recent advances in neuronal imaging have enabled the observation of mitochondria in live brains for long periods of time, enabling the study of their dynamics in animal models of diseases. To aid these studies, we developed an automatic method, based on supervised learning, for quantifying the degree of mitochondrial fragmentation in tissue images acquired via two-photon microscopy from transgenic mice, which exclusively express Enhanced cyan fluorescent protein (ECFP) under Thy1 promoter, targeted to the mitochondrial matrix in subpopulations of neurons. We tested the method on images prior to and after cardiac arrest, and found it to be sensitive to significant changes in mitochondrial morphology because of the arrest. We conclude that the method is useful in detecting morphological abnormalities in mitochondria and, likely, in other subcellular structures as well. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  4. Concentration of atomic hydrogen in a dielectric barrier discharge measured by two-photon absorption fluorescence

    Science.gov (United States)

    Dvořák, P.; Talába, M.; Obrusník, A.; Kratzer, J.; Dědina, J.

    2017-08-01

    Two-photon absorption laser-induced fluorescence (TALIF) was utilized for measuring the concentration of atomic hydrogen in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar, H2 and O2 at atmospheric pressure. The method was calibrated by TALIF of krypton diluted in argon at atmospheric pressure, proving that three-body collisions had a negligible effect on quenching of excited krypton atoms. The diagnostic study was complemented with a 3D numerical model of the gas flow and a zero-dimensional model of the chemistry in order to better understand the reaction kinetics and identify the key pathways leading to the production and destruction of atomic hydrogen. It was determined that the density of atomic hydrogen in Ar-H2 mixtures was in the order of 1021 m-3 and decreased when oxygen was added into the gas mixture. Spatially resolved measurements and simulations revealed a sharply bordered region with low atomic hydrogen concentration when oxygen was added to the gas mixture. At substoichiometric oxygen/hydrogen ratios, this H-poor region is confined to an area close to the gas inlet and it is shown that the size of this region is not only influenced by the chemistry but also by the gas flow patterns. Experimentally, it was observed that a decrease in H2 concentration in the feeding Ar-H2 mixture led to an increase in H production in the DBD.

  5. Plasma magnetic field diagnostic using two-photon Doppler-free LIF

    Science.gov (United States)

    Yoon, Young Dae; Bellan, Paul

    2015-11-01

    A detailed description of a new plasma B field diagnostic using Doppler-free two-photon laser-induced fluorescence is presented. The diagnostic is based on a method previously developed in the context of rubidium vapor experiments. Two counter-propagating 393nm diode laser beams are directed into an argon plasma to excite Ar-II ions from 3s2 3p4 4 s4P1 / 2 ⟶ 3s2 3p4 4 p4S3 / 2 ⟶ 3s2 3p4 4 d4P3 / 2 . These levels involve two similar (392.86 and 393.25nm) transition wavelengths, so the two counter-propagating beams effectively cancel out the Doppler effect. The excited ions then decay to the 3s2 3p4 4 p4P1 / 2 level, emitting a 324.98nm line which is to be detected by a photomultiplier tube. The Zeeman splitting -- normally unobservable because of the large Doppler broadening -- of the resultant fluorescence is then to be analyzed, yielding the magnetic field of the particular location. This method is expected to provide a 3-D localized, non-perturbing measurement of magnetic fields. An experimental implementation is currently in progress.

  6. Two-photon exchange force in scalar quantum electrodynamics: The asymptotic story

    International Nuclear Information System (INIS)

    Sucher, J.

    1994-01-01

    The dependence of the potential V 2γ arising from two-photon exchange between charged spinless systems on the one-photon exchange potential V 1γ is examined. It is found that, unlike the case when at least one of the two systems is neutral, the form of V 1γ can play a key role in determining the large-r behavior of V 2γ . It is shown that if V 1γ is defined in a way inspired by the use of the Coulomb gauge rather than the Feynman gauge, V 2γ falls off as r -3 , rather than as r -2 . This result, which removes an apparent cognitive dissonance with the related work of Spruch, does not mean that the effective potential is inherently gauge dependent. Instead it highlights the fact that in this case the concept of the asymptotic behavior of V 2γ is not as sharp as one might have thought. The relation of this result to an analogous one expected to hold for spinor QED and to the nonrelativistic form of the orbit-orbit interaction is also discussed

  7. Visualization of laser tattoo removal treatment effects in a mouse model by two-photon microscopy.

    Science.gov (United States)

    Jang, Won Hyuk; Yoon, Yeoreum; Kim, Wonjoong; Kwon, Soonjae; Lee, Seunghun; Song, Duke; Choi, Jong Woon; Kim, Ki Hean

    2017-08-01

    Laser tattoo removal is an effective method of eliminating tattoo particles in the skin. However, laser treatment cannot always remove the unwanted tattoo completely, and there are risks of either temporary or permanent side effects. Studies using preclinical animal models could provide detailed information on the effects of laser treatment in the skin, and might help to minimize side effects in clinical practices. In this study, two-photon microscopy (TPM) was used to visualize the laser treatment effects on tattoo particles in both phantom specimens and in vivo mouse models. Fluorescent tattoo ink was used for particle visualization by TPM, and nanosecond (ns) and picosecond (ps) lasers at 532 nm were used for treatment. In phantom specimens, TPM characterized the fragmentation of individual tattoo particles by tracking them before and after the laser treatment. These changes were confirmed by field emission scanning electron microscopy (FE-SEM). TPM was used to measure the treatment efficiency of the two lasers at different laser fluences. In the mouse model, TPM visualized clusters of tattoo particles in the skin and detected their fragmentation after the laser treatment. Longitudinal TPM imaging observed the migration of cells containing tattoo particles after the laser treatment. These results show that TPM may be useful for the assessment of laser tattoo removal treatment in preclinical studies.

  8. High-capacity quantum secure direct communication with two-photon six-qubit hyperentangled states

    Science.gov (United States)

    Wu, FangZhou; Yang, GuoJian; Wang, HaiBo; Xiong, Jun; Alzahrani, Faris; Hobiny, Aatef; Deng, FuGuo

    2017-12-01

    This study proposes the first high-capacity quantum secure direct communication (QSDC) with two-photon six-qubit hyper-entangled Bell states in two longitudinal momentum and polarization degrees of freedom (DOFs) of photon pairs, which can be generated using two 0.5 mm-thick type-I β barium borate crystal slabs aligned one behind the other and an eight-hole screen. The secret message can be independently encoded on the photon pairs with 64 unitary operations in all three DOFs. This protocol has a higher capacity than previous QSDC protocols because each photon pair can carry 6 bits of information, not just 2 or 4 bits. Our QSDC protocol decreases the influence of decoherence from environment noise by exploiting the decoy photons to check the security of the transmission of the first photon sequence. Compared with two-way QSDC protocols, our QSDC protocol is immune to an attack by an eavesdropper using Trojan horse attack strategies because it is a one-way quantum communication. The QSDC protocol has good applications in the future quantum communication because of all these features.

  9. Comparative study of two-photon fluorescent bio-markers at nanosecond and femtosecond pulsed excitation

    Science.gov (United States)

    Peterson, Burl H.; Sarkisov, Sergey S.; Nesterov, V. N.; Curley, Michael J.; Urbas, Augustine; Patel, Darayas N.; Wang, J.-C.

    2007-02-01

    In this study we investigate visible fluorescence of cytotoxic bio-markers (molecular probes) based on the derivatives of piperidone at femtosecond infrared pulsed laser excitation. The subject of this investigation is the origin of the fluorescence. Does it originate from the excited state absorption, which occurs only at slow, nanosecond excitation, or is it due to intrinsic multi-photon absorption? In the past, it has been shown indirectly, through the laser photolysis study, that the contribution of the excited state absorption is minimal for several compounds of such type. The results of direct experiments with an infrared femtosecond fiber laser as an excitation source described here support this hypothesis. The observed dependence of the fluorescence on the pump power indicated the contribution of not only two-photon, but multi-photon routes of excitation. Additionally, it was shown that the spectral features of the fluorescence correlate with the presence of glycine, an amino acid that is one of the building blocks of proteins in a cell. The implication of this result is, in addition to their anticancer action, the compounds can possibly be used for fluorescent diagnostics of cancer and multi-photon fluorescent microscopy of malignant cell cultures using portable infrared fiber lasers as excitation sources.

  10. A review on the processing accuracy of two-photon polymerization

    International Nuclear Information System (INIS)

    Zhou, Xiaoqin; Hou, Yihong; Lin, Jieqiong

    2015-01-01

    Two-photon polymerization (TPP) is a powerful and potential technology to fabricate true three-dimensional (3D) micro/nanostructures of various materials with subdiffraction-limit resolution. And it has been applied to microoptics, electronics, communications, biomedicine, microfluidic devices, MEMS and metamaterials. These applications, such as microoptics and photon crystals, put forward rigorous requirements on the processing accuracy of TPP, including the dimensional accuracy, shape accuracy and surface roughness and the processing accuracy influences their performance, even invalidate them. In order to fabricate precise 3D micro/nanostructures, the factors influencing the processing accuracy need to be considered comprehensively and systematically. In this paper, we review the basis of TPP micro/nanofabrication, including mechanism of TPP, experimental set-up for TPP and scaling laws of resolution of TPP. Then, we discuss the factors influencing the processing accuracy. Finally, we summarize the methods reported lately to improve the processing accuracy from improving the resolution and changing spatial arrangement of voxels

  11. Two Photon Decay Widths of Charmonium Resonances Formed in Proton Antiproton Annihilations

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Michelle Dawn [UC, Irvine

    1999-01-01

    E835 is an experiment dedicated to the precision study of charmonium formed in $\\bar{p}p$ annihilations at the Fermilab Antiproton Accumulator. E835 has measured the resonance parameters of the $\\eta_c$ resonance: $M(\\eta_c$) = 2985.4 $\\pm$ 2.1 MeV, ,($\\eta_c$) = 21.1 $\\pm$ $^{7.5}_{6.2}$ MeV, and, ($\\eta_c \\to \\gamma\\gamma$ ) = 3.9 $^{1.5}_{ 1.3}$ $\\pm$ $^{1.8}_ {1.1}$. Also reported is the two photon width of the $X_2$,,($X_2 \\to \\gamma\\gamma$) = 0.29 $\\pm$ 0.06 $\\pm$ 0:04. A search for the $\\eta^{\\prime}_c$ resonance has resulted in an upper limit for the product of the branching ratios $B(\\eta^{\\prime}_c \\to \\bar{p}p$) x $B(\\eta^{\\prime}_c \\to \\gamma\\gamma$ ) < 12 x $10^{-8}$. An upper limit, ($\\chi_0 \\to \\gamma\\gamma$) < 2.7 keV is set.

  12. A flow bioreactor system compatible with real-time two-photon fluorescence lifetime imaging microscopy.

    Science.gov (United States)

    Shen, Nian; Riedl, Julia A; Carvajal Berrio, Daniel A; Davis, Zachary; Monaghan, Michael G; Layland, Shannon L; Hinderer, Svenja; Schenke-Layland, Katja

    2018-02-02

    Bioreactors are essential cell and tissue culture tools that allow the introduction of biophysical signals into in vitro cultures. One major limitation is the need to interrupt experiments and sacrifice samples at certain time points for analyses. To address this issue, we designed a bioreactor that combines high-resolution contact-free imaging and continuous flow in a closed system that is compatible with various types of microscopes. The high throughput fluid flow bioreactor was combined with two-photon fluorescence lifetime imaging microscopy (2P-FLIM) and validated. The hydrodynamics of the bioreactor chamber were characterized using COMSOL. The simulation of shear stress indicated that the bioreactor system provides homogeneous and reproducible flow conditions. The designed bioreactor was used to investigate the effects of low shear stress on human umbilical vein endothelial cells (HUVECs). In a scratch assay, we observed decreased migration of HUVECs under shear stress conditions. Furthermore, metabolic activity shifts from glycolysis to oxidative phosphorylation-dependent mechanisms in HUVECs cultured under low shear stress conditions were detected using 2P-FLIM. Future applications for this bioreactor range from observing cell fate development in real-time to monitoring the environmental effects on cells or metabolic changes due to drug applications.

  13. Designing a large field-of-view two-photon microscope using optical invariant analysis.

    Science.gov (United States)

    Bumstead, Jonathan R; Park, Jasmine J; Rosen, Isaac A; Kraft, Andrew W; Wright, Patrick W; Reisman, Matthew D; Côté, Daniel C; Culver, Joseph P

    2018-04-01

    Conventional two-photon microscopy (TPM) is capable of imaging neural dynamics with subcellular resolution, but it is limited to a field-of-view (FOV) diameter [Formula: see text]. Although there has been recent progress in extending the FOV in TPM, a principled design approach for developing large FOV TPM (LF-TPM) with off-the-shelf components has yet to be established. Therefore, we present a design strategy that depends on analyzing the optical invariant of commercially available objectives, relay lenses, mirror scanners, and emission collection systems in isolation. Components are then selected to maximize the space-bandwidth product of the integrated microscope. In comparison with other LF-TPM systems, our strategy simplifies the sequence of design decisions and is applicable to extending the FOV in any microscope with an optical relay. The microscope we constructed with this design approach can image [Formula: see text] lateral and [Formula: see text] axial resolution over a 7-mm diameter FOV, which is a 100-fold increase in FOV compared with conventional TPM. As a demonstration of the potential that LF-TPM has on understanding the microarchitecture of the mouse brain across interhemispheric regions, we performed in vivo imaging of both the cerebral vasculature and microglia cell bodies over the mouse cortex.

  14. Biomimicry at the nanoscale: current research and perspectives of two-photon polymerization

    Science.gov (United States)

    Marino, Attilio; Filippeschi, Carlo; Mattoli, Virgilio; Mazzolai, Barbara; Ciofani, Gianni

    2015-02-01

    Living systems such as cells and tissues are extremely sensitive to their surrounding physico-chemical microenvironment. In the field of regenerative medicine and tissue engineering, the maintenance of culture conditions suitable for the formation of proliferation niches, for the self-renewal maintenance of stem cells, or for the promotion of a particular differentiation fate is an important issue that has been addressed using different strategies. A number of investigations suggests that a particular cell behavior can be in vitro resembled by mimicking the corresponding in vivo conditions. In this context, several biomimetic environments have been designed in order to control cell phenotypes and functions. In this review, we will analyze the most recent examples of the control of the in vitro physical micro/nano-environment by exploiting an innovative technique of high resolution 3D photolithography, the two-photon polymerization (2pp). The biomedical applications of this versatile and disruptive computer assisted design/manufacturing technology are very wide, and range from the fabrication of biomimetic and nanostructured scaffolds for tissue engineering and regenerative medicine, to the microfabrication of biomedical devices, like ossicular replacement prosthesis and microneedles.

  15. Comparison of confocal microscopy and two-photon microscopy in mouse cornea in vivo.

    Science.gov (United States)

    Lee, Jun Ho; Lee, Seunghun; Gho, Yong Song; Song, In Seok; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

    2015-03-01

    High-resolution imaging of the cornea is important for studying corneal diseases at cellular levels. Confocal microscopy (CM) has been widely used in the clinic, and two-photon microscopy (TPM) has recently been introduced in various pre-clinical studies. We compared the performance of CM and TPM in normal mouse corneas and neovascularized mouse corneas induced by suturing. Balb/C mice and C57BL/6 mice expressing green fluorescent protein (GFP) were used to compare modalities based on intrinsic contrast and extrinsic fluorescence contrast. CM based on reflection (CMR), CM based on fluorescence (CMF), and TPM based on intrinsic/extrinsic fluorescence and second harmonic generation (SHG) were compared by imaging the same sections of mouse corneas sequentially in vivo. In normal mouse corneas, CMR visualized corneal cell morphologies with some background noise, and CMF visualized GFP expressing corneal cells clearly. TPM visualized corneal cells and collagen in the stroma based on fluorescence and SHG, respectively. However, in neovascularized mouse corneas, CMR could not resolve cells deep inside the cornea due to high background noise from the effects of increased structural irregularity induced by suturing. CMF and TPM visualized cells and induced vasculature better than CMR because both collect signals from fluorescent cells only. Both CMF and TPM had signal decays with depth due to the structural irregularity, with CMF having faster signal decay than TPM. CMR, CMF, and TPM showed different degrees of image degradation in neovascularized mouse corneas. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Combined two-photon microscopy and optical coherence tomography using individually optimized sources

    Science.gov (United States)

    Jeong, Bosu; Lee, Byunghak; Jang, Min Seong; Nam, Hyoseok; Kim, Hae Koo; Yoon, Sang June; Doh, Junsang; Lee, Sang-Joon; Yang, Bo-Gie; Jang, Myoung Ho; Kim, Ki Hean

    2011-03-01

    Two-photon microscopy (TPM) and optical coherence tomography (OCT) are 3D tissue imaging techniques based on different contrast mechanisms. We developed a combined system of TPM and OCT to provide information of both imaging modalities for in-vivo tissue study. TPM and OCT were implemented by using separate light sources, a Ti-Sapphire laser and a wavelength-swept source centered at 1300 nm respectively, and scanners. Light from the two sources was combined for the simultaneous imaging of tissue samples. TPM provided molecular, cellular information of tissues in the region of a few hundred microns on one side at a sub-cellular resolution, and ran at approximately 40 frames per second. OCT provided structural information in the tissue region larger than TPM images at a sub-tenth micron resolution by using 0.1 numerical aperture. OCT had the field of view of 800 um × 800 um based on a 20x objective, the sensitivity of 97dB, and the imaging speed of 0.8 volumes per second. This combined system was tested with simple microsphere specimens, and then was applied to image the explanted intestine of a mouse model and the plant leaves. Morphology and micro-structures of the intestine villi and immune cells within the villi were shown in the intestine image, and chloroplasts and various microstructures of the maize leaves were visualized in 3D by the combined system.

  17. Angular distributions of photoelectrons from resonant two-photon ionization: A graphical approach

    International Nuclear Information System (INIS)

    Chien, R.

    1984-01-01

    The Liouville representation is a formalism that describes quantum mechanical problems by using the space of density operators as kets and the space of observable operators as bras. It is useful for problems with complicated angular momentum coupling because it gives directly the probabilities and expectation values rather than probability amplitudes, so that some of the extended and tedious steps of the angular momentum algebra are eliminated. The graphical representation of angular momentum coupling has proved itself as another way to simplify and clarify calculations; graphical representation helps one to visualize the physics and simplifies and organizes the computations. By combining the graphical method and Liouville representation, we introduce a simple, transparent method to deal with problems of many coupled angular momenta. We use this formalism to derive the analytic expression for the angular distributions of photoelectrons. The angular distributions are represented by diagrams of density matrix and detector operators and a diagram of the transition matrix. The analytic expressions are then obtained from the diagrams by following simple general rules for the graphical reduction. A specific example, angular distributions of photoelectrons from resonant two-photon ionization of alkali atoms with hyperfine interaction, is also given

  18. Automated 3-D Detection of Dendritic Spines from In Vivo Two-Photon Image Stacks.

    Science.gov (United States)

    Singh, P K; Hernandez-Herrera, P; Labate, D; Papadakis, M

    2017-10-01

    Despite the significant advances in the development of automated image analysis algorithms for the detection and extraction of neuronal structures, current software tools still have numerous limitations when it comes to the detection and analysis of dendritic spines. The problem is especially challenging in in vivo imaging, where the difficulty of extracting morphometric properties of spines is compounded by lower image resolution and contrast levels native to two-photon laser microscopy. To address this challenge, we introduce a new computational framework for the automated detection and quantitative analysis of dendritic spines in vivo multi-photon imaging. This framework includes: (i) a novel preprocessing algorithm enhancing spines in a way that they are included in the binarized volume produced during the segmentation of foreground from background; (ii) the mathematical foundation of this algorithm, and (iii) an algorithm for the detection of spine locations in reference to centerline trace and separating them from the branches to whom spines are attached to. This framework enables the computation of a wide range of geometric features such as spine length, spatial distribution and spine volume in a high-throughput fashion. We illustrate our approach for the automated extraction of dendritic spine features in time-series multi-photon images of layer 5 cortical excitatory neurons from the mouse visual cortex.

  19. Improvement of distortion error for fabricating precision microparts using two-photon photopolymerization

    International Nuclear Information System (INIS)

    Kim, Jung-Dae; Lee, Yong-Gu

    2016-01-01

    The manufacturing accuracy of microparts produced using two-photon polymerization depends on the accuracy of control of the positions of the focal spot. The accuracy becomes more important when these microparts need to be assembled into a whole with parts that are free to move in relation to each other. Ideally, the exact location of the movement of the focal spots in an optical system, no matter how complex it may be, can be solved using geometric optics. However, in reality, this is not so easy because of the complexity of optical systems and also due to the imperfections that lie between the design and the physical layout. We thus take a black-box approach such that the optical system is not examined but only the output result, and the command from the system is compared, interpreted and finally calibrated. The result is an extremely simple, yet very effective adaptation of the commanding of the focal spot that only requires the focal spot at the manufacturing plane to be monitored through a digital camera. We have also shown the effectiveness of the proposed method by fabricating a microstructure and measuring the fabrication error, which was found to be less than 3%. (paper)

  20. Scaled-Absorption and Recurrence Spectra of Argon in an Electric Field Using Two Photon Excitation

    Science.gov (United States)

    Wright, J. D.; Huang, W.; Flores-Rueda, H.; Morgan, T. J.

    2001-05-01

    For multi-electron atoms in an electric field, low angular momentum Rydberg electrons strongly interact with the atomic core causing scattering which can be associated with the presence of chaos. The photoabsorption spectra exhibits extraordinary complex structure but is still in principle interpretable semiclassically using closed orbit theory and semiclassical S-matrix theory [1]. Previously we measured the scaled-photoabsorption and recurrence spectra of argon in an electric field, using single uv-photon excitation from a metastable state [2]. We have extended these measurements to two photon excitation from the same initial state, which allows access to different angular momentum states. The effect of multi-photon excitation on the structure of the recurrence spectrum and its subsequent semiclassical interpretation will be presented. Work supported by the National Science Foundation. [1] B. E. Granger and C. H. Greene, Phys.Rev.A 62, 12511 (2000) [2] H. Flores-Rueda, J. D. Wright, W. Huang, T. J. Morgan, Bull. Am. Phys. Soc. 45, 94 (2000)

  1. In situ imaging of the mouse cochlea using two-photon microscopy

    Science.gov (United States)

    Yang, Xin; Pu, Ye; Psaltis, Demetri; Stankovic, Konstantina M.

    2013-04-01

    Intracochlear imaging is of great interest clinically because cochlea is the central organ of hearing. However, intracochlear imaging is technologically challenging due to the cochlea's small size and encasement in bone. The state-of- the-art imaging techniques are not adequate for high resolution cellular imaging to establish diagnosis without destroying the cochlea. We report in situ imaging of intact mouse cochlea using endogenous two-photon excitation fluorescence (TPEF) as the contrast mechanism. TPEF eliminates the need for exogenous labeling and eradicating the staining-induced artifacts. We used a natural, membranous opening into the cochlea, the round window, as the optical access to reach the organ of Corti, requiring no additional slicing or opening. Our approach provides the maximum non-invasiveness in the imaging process. TPEF exhibits strong contrast allowing deep imaging of mouse cochlea with cellular and even subcellular resolution. Inner hair cell, outer hair cell and supporting cell are clearly identifiable in TPEF images. Distinct morphological differences are observed between healthy and noise-exposed cochleae, allowing detection of specific, noise-induced pathologic changes. The TPEF images taken through the round window are correlated with the whole mount sections, verifying their reliability. Compared with one-photon excitation fluorescence (OPEF) confocal microscope and wide-field transmission microscope images taken under the same magnification and resolution, TPEF images demonstrate clear advantages in terms of sharpness, signal to noise ratio and contrast. These capabilities provide a working foundation for microendoscopy-based clinical diagnostics of sensorineural hearing loss.

  2. Strong two-photon absorption of Mn-doped CsPbCl3 perovskite nanocrystals

    Science.gov (United States)

    He, Tingchao; Li, Junzi; Ren, Can; Xiao, Shuyu; Li, Yiwen; Chen, Rui; Lin, Xiaodong

    2017-11-01

    Emerging CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) have been demonstrated to be efficient emitters with a high fluorescence quantum yield, making these materials interesting for optical applications as well as for fundamental physics. Interestingly, doping with transition metal ions has been extensively explored as a way of introducing new optical, electronic, and magnetic properties, making perovskite NCs much more functional than their undoped counterparts. However, there have been no reports regarding the nonlinear optical properties of transition metal ion doped perovskite NCs. Herein, by using femtosecond-transient absorption spectroscopy, we have determined the one-photon linear absorption cross-section (˜1.42 × 10-14 cm2) of Mn-doped CsPbCl3 NCs (˜11.7 ± 1.8 nm size, ˜0.2% doping concentration, and ˜600 nm emission wavelength). More importantly, their nonlinear optical properties—in particular, the two-photon absorption (TPA) and resultant emission—were investigated. Notably, the NCs exhibit wavelength-dependent TPA with a maximum value up to ˜3.18 × 105 GM at a wavelength of 720 nm. Our results indicate that Mn-doped CsPbCl3 NCs show promise in nonlinear optical devices and multiphoton fluorescence lifetime imaging.

  3. Preparation of a novel ferrofluidic photoresist for two-photon photopolymerization technique

    International Nuclear Information System (INIS)

    Tian Ye; Lu Dongxiao; Jiang Haobo; Lin Xiaomei

    2012-01-01

    We present a novel route for the preparation of ferrofluidic photoresist compatible with two-photon photopolymerization (TPP). To get a homogeneous ferrofluidic photoresit, the compatibility of photoresist and magnetic materials has been improved. Monodispersed Fe 3 O 4 nanoparticles synthesized via thermal decomposition of iron precursor were stabilized by 6-(methacryloyloxy) hexanoic acid (a kind of acrylate-based monomer). A ferrofluidic photoresist was prepared by doping the modified Fe 3 O 4 nanoparticles in acrylate-based resin. In this way, the dispersibility of nanoparticles in photoresist was enhanced significantly. As a representative example, a precise magnetic micron-sized spring was created. In the test of the magnetic response, the sensitivity of magnetic microspring was improved remarkably due to the optimization of the ferrofluidic photoresist. When the intensity of external magnetic field reached a value of 1500 Gs, the deformation rate of the microspring would get to 2.25, indicating the compatibility of the ferrofluidic photoresist in microfabrication. - Highlights: ► A novel ferrofluid photoresist was developed for TPP fabrication. ► A micrometer-sized magnetic spring was successfully created. ► Performance of microsprings was highly improved due to the optimization of nanoparticles.

  4. A review on the processing accuracy of two-photon polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaoqin; Hou, Yihong [School of Mechanical Science and Engineering, Jilin University, Changchun, 130022 (China); Lin, Jieqiong, E-mail: linjieqiong@mail.ccut.edu.cn [School of Electromechanical Engineering, Changchun University of Technology, Changchun, 130012 (China)

    2015-03-15

    Two-photon polymerization (TPP) is a powerful and potential technology to fabricate true three-dimensional (3D) micro/nanostructures of various materials with subdiffraction-limit resolution. And it has been applied to microoptics, electronics, communications, biomedicine, microfluidic devices, MEMS and metamaterials. These applications, such as microoptics and photon crystals, put forward rigorous requirements on the processing accuracy of TPP, including the dimensional accuracy, shape accuracy and surface roughness and the processing accuracy influences their performance, even invalidate them. In order to fabricate precise 3D micro/nanostructures, the factors influencing the processing accuracy need to be considered comprehensively and systematically. In this paper, we review the basis of TPP micro/nanofabrication, including mechanism of TPP, experimental set-up for TPP and scaling laws of resolution of TPP. Then, we discuss the factors influencing the processing accuracy. Finally, we summarize the methods reported lately to improve the processing accuracy from improving the resolution and changing spatial arrangement of voxels.

  5. Preparation of a novel ferrofluidic photoresist for two-photon photopolymerization technique

    Energy Technology Data Exchange (ETDEWEB)

    Tian Ye [College of Electrical and Electronic Engineering, Changchun University of Technology, 2055 Yan' an Street, Changchun 130012 (China); Lu Dongxiao; Jiang Haobo [College of Physics, Jilin University, 119 Jiefang Road, Changchun 130023 (China); Lin Xiaomei, E-mail: linxiaomei@mail.ccut.edu.cn [College of Electrical and Electronic Engineering, Changchun University of Technology, 2055 Yan' an Street, Changchun 130012 (China)

    2012-10-15

    We present a novel route for the preparation of ferrofluidic photoresist compatible with two-photon photopolymerization (TPP). To get a homogeneous ferrofluidic photoresit, the compatibility of photoresist and magnetic materials has been improved. Monodispersed Fe{sub 3}O{sub 4} nanoparticles synthesized via thermal decomposition of iron precursor were stabilized by 6-(methacryloyloxy) hexanoic acid (a kind of acrylate-based monomer). A ferrofluidic photoresist was prepared by doping the modified Fe{sub 3}O{sub 4} nanoparticles in acrylate-based resin. In this way, the dispersibility of nanoparticles in photoresist was enhanced significantly. As a representative example, a precise magnetic micron-sized spring was created. In the test of the magnetic response, the sensitivity of magnetic microspring was improved remarkably due to the optimization of the ferrofluidic photoresist. When the intensity of external magnetic field reached a value of 1500 Gs, the deformation rate of the microspring would get to 2.25, indicating the compatibility of the ferrofluidic photoresist in microfabrication. - Highlights: Black-Right-Pointing-Pointer A novel ferrofluid photoresist was developed for TPP fabrication. Black-Right-Pointing-Pointer A micrometer-sized magnetic spring was successfully created. Black-Right-Pointing-Pointer Performance of microsprings was highly improved due to the optimization of nanoparticles.

  6. Two-photon exchange force in scalar quantum electrodynamics: The asymptotic story

    Science.gov (United States)

    Sucher, J.

    1994-04-01

    The dependence of the potential V2γ arising from two-photon exchange between charged spinless systems on the one-photon exchange potential V1γ is examined. It is found that, unlike the case when at least one of the two systems is neutral, the form of V1γ can play a key role in determining the large-r behavior of V2γ. It is shown that if V1γ is defined in a way inspired by the use of the Coulomb gauge rather than the Feynman gauge, V2γ falls off as r-3, rather than as r-2. This result, which removes an apparent cognitive dissonance with the related work of Spruch, does not mean that the effective potential is inherently gauge dependent. Instead it highlights the fact that in this case the concept of the asymptotic behavior of V2γ is not as sharp as one might have thought. The relation of this result to an analogous one expected to hold for spinor QED and to the nonrelativistic form of the orbit-orbit interaction is also discussed.

  7. Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio

    CERN Document Server

    Hori, Masaki; Barna, Daniel; Andreas Dax,; Hayano, Ryugo; Friedreich, Susanne; Juhász, Bertalan; Pask, Thomas; Widmann, Eberhard; Horváth, Dezső; Venturelli, Luca; Zurlo, Nicola; 10.1038/nature10260

    2013-01-01

    Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium ($\\bar{p}He^+$) is a three-body atom2 consisting of a normal helium nucleus, an electron in its ground state and an antiproton ($\\bar{p}$) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which $\\bar{p}^{3}He^{+}$ and $\\bar{p}^{4}He^{+}$ isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-phot...

  8. Label-free in vivo imaging of human leukocytes using two-photon excited endogenous fluorescence

    Science.gov (United States)

    Zeng, Yan; Yan, Bo; Sun, Qiqi; Teh, Seng Khoon; Zhang, Wei; Wen, Zilong; Qu, Jianan Y.

    2013-04-01

    We demonstrate that two-photon excited endogenous fluorescence enables label-free morphological and functional imaging of various human blood cells. Specifically, we achieved distinctive morphological contrast to visualize morphology of important leukocytes, such as polymorphonuclear structure of granulocyte and mononuclear feature of agranulocyte, through the employment of the reduced nicotinamide adenine dinucleotide (NADH) fluorescence signals. In addition, NADH fluorescence images clearly reveal the morphological transformation process of neutrophils during disease-causing bacterial infection. Our findings also show that time-resolved NADH fluorescence can be potentially used for functional imaging of the phagocytosis of pathogens by leukocytes (neutrophils) in vivo. In particular, we found that free-to-bound NADH ratios measured in infected neutrophils increased significantly, which is consistent with a previous study that the energy consumed in the phagocytosis of neutrophils is mainly generated through the glycolysis pathway that leads to the accumulation of free NADH. Future work will focus on further developing and applying label-free imaging technology to investigate leukocyte-related diseases and disorders.

  9. Ultrafast axial scanning for two-photon microscopy via a digital micromirror device and binary holography.

    Science.gov (United States)

    Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Wang, Dien; Chen, Shih-Chi

    2016-04-01

    In this Letter, we present an ultrafast nonmechanical axial scanning method for two-photon excitation (TPE) microscopy based on binary holography using a digital micromirror device (DMD), achieving a scanning rate of 4.2 kHz, scanning range of ∼180  μm, and scanning resolution (minimum step size) of ∼270  nm. Axial scanning is achieved by projecting the femtosecond laser to a DMD programmed with binary holograms of spherical wavefronts of increasing/decreasing radii. To guide the scanner design, we have derived the parametric relationships between the DMD parameters (i.e., aperture and pixel size), and the axial scanning characteristics, including (1) maximum optical power, (2) minimum step size, and (3) scan range. To verify the results, the DMD scanner is integrated with a custom-built TPE microscope that operates at 60 frames per second. In the experiment, we scanned a pollen sample via both the DMD scanner and a precision z-stage. The results show the DMD scanner generates images of equal quality throughout the scanning range. The overall efficiency of the TPE system was measured to be ∼3%. With the high scanning rate, the DMD scanner may find important applications in random-access imaging or high-speed volumetric imaging that enables visualization of highly dynamic biological processes in 3D with submillisecond temporal resolution.

  10. Elucidation of two photon absorption of ethylenediaminium (2,4-dinitrophenolate) crystals

    Science.gov (United States)

    Indumathi, C.; Sabari Girisun, T. C.; Anitha, K.; Cecil Raj, S. Alfred

    2016-10-01

    Optical quality single crystals of ethylenediaminium (2,4-dinitrophenolate) [EDA(2,4)DNP] were grown by solvent evaporation method for optical limiting applications against intense ultrashot pulse lasers. Single crystal XRD showed that the material crystallizes in monoclinic system with centric space group P21/C. The crystal packing diagram was elucidated for the first time in literature and it revealed six hydrogen bonds played a very important role in stabilizing the structure. A bifurcated hydrogen bond was also observed between ethylenediamminium and dinitrophenolate ions. The formation of charge transfer complex during the reaction of ethylenediamine and 2,4-dinitrophenol was strongly evident through the vibrational spectroscopic studies. TG-DTA and DSC curves indicate that the material exhibited strong decomposition at 224 °C. Ground state absorption analysis showed that the grown crystals possess absorption maxima in UV region (270 nm, 346 nm) and wide optical transmittance window (480-1200 nm) in the entire visible and NIR region. Measurement of two photon absorption (2PA) and optical limiting response by Z-scan technique under nanosecond pulse excitation was reported. Hence EDA(2,4)DNP with high 2PA coefficient (0.79 ± 0.04 × 10-10 m/W) and low limiting threshold (2.40 ± 0.05 × 1012 W/m2) will be a potential candidate for optical limiting applications like eye and sensor protection against short pulse lasers that are well spread in human interactive sectors.

  11. Interim report on modeling studies of two-photon isotope separation

    International Nuclear Information System (INIS)

    Hwang, W.C.; Badcock, C.C.; Kamada, R.F.

    1975-01-01

    The two-photon or two-step dissociation method of laser induced isotope enrichment is being modeled for the HBrNO photochemical system. In the model, H 79 Br is selectively excited by resonance IR laser radiation and then dissociated by uv radiation. Selectively dissociated Br atoms are scavenged to form isotopically enriched BrNO and Br 2 . This model includes all kinetic and absorption processes found to be significant and the time-varying concentrations of any species involved in a significant process. Among these processes are vibrational energy transfer reactions (including isotopic exchange) involving HBr v = 0 - 3, rotational and translational (velocity) relaxation processes, dissociation of HBr in the v = 0 - 3 levels, and secondary chemical reactions of the dissociation products. The absorption and kinetic processes that are most important to 79 Br enrichment have been identified and the study of the effects on enrichment upon variation of external parameters (such as reactant pressure, ir or uv source intensity, and temperature) is in progress. Some preliminary results are: (1) intensity of the ir source is usually more important than the uv intensity; (2) chemical reactions are the dominant kinetic processes at lower pressures while energy transfer reactions dominate at higher pressures; (3) kinetic processes usually have greater effect on the absolute amount of enriched products; (4) isotopic abundance of 79 Br in the products can range from 0.55 to 0.80 for the conditions used in the model

  12. Luminosity measurements and two-photon physics with the DELPHI VSAT at LEP

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Per M.

    1998-02-01

    This thesis describes analysis of data from the DELPHI Very Small Angle Tagger (VSAT) calorimeter at LEP1. The VSAT consists of four Silicon-Tungsten calorimeter modules symmetrically positioned 7.7 meters away from the inter-action point. It measures elastically scattered electrons and positrons, Bhabha events, within the polar angular region between 5-12 mrad. Trigger efficiency and reconstruction procedures for the energy and position measurement of VSAT data are described. Off momentum electron background and online luminosity monitoring with the VSAT are also discussed. The extraction of various beam-parameters from analysis of the impact point of Bhabha pairs reveal the ability to measure variations in beam angles with a precision of 50 microrad. The relative luminosity measurement of the VSAT with a precision level of 0.1% for the 1993-1994 Z{sup 0} scan is also presented. Through the study of double-tag-photon events, using the VSAT for measuring the energy of both scattered electrons, the behaviour of the total hadronic two-photon cross section is for the first time investigated up to invariant masses of 35 GeV. 55 refs, 39 figs, 8 tabs.

  13. Two-photon microscopy measurement of CMRO2 using periarteriolar PO2 gradients(Conference Presentation)

    Science.gov (United States)

    Sakadžić, Sava; Yaseen, Mohammad A.; Jaswal, Rajeshwer S.; Roussakis, Emmanuel; Dale, Anders M.; Buxton, Richard B.; Vinogradov, Sergei A.; Boas, David A.; Devor, Anna

    2017-02-01

    The cerebral metabolic rate of oxygen (CMRO2) is an essential parameter for evaluating brain function and pathophysiology. Measurements of CMRO2 with high spatio-temporal resolution are critically important for understanding how the brain copes with metabolic and blood perfusion changes associated with various clinical conditions, such as stroke, periinfarct depolarizations, and various microvasculopathies (e.g., Alzheimer's disease, chronic hypertension). CMRO2 measurements are also important for understanding the physiological underpinnings of functional Magnetic Resonance Imaging signals. However, the currently available approaches for quantifying CMRO2 rely on complex multimodal imaging and mathematical modeling. Here, we introduce a novel method that allows estimation of CMRO2 based on a single measurement modality - two-photon phosphorescence lifetime microscopy (2PLM) imaging of the partial pressure of oxygen (PO2) in cortical tissue. CMRO2 is estimated by fitting the changes of tissue PO2 around cortical penetrating arterioles with the Krogh cylinder model of oxygen diffusion. We measured the baseline CMRO2 in anesthetized rats, and modulated tissue PO2 levels by manipulating the depth of anesthesia. This method has a spatial resolution of approximately 200 μm and it may provide CMRO2 measurements in individual cortical layers or within confined cortical regions such as in ischemic penumbra and the foci of functional activation.

  14. Brain Tissue PO2 Measurement During Normoxia and Hypoxia Using Two-Photon Phosphorescence Lifetime Microscopy.

    Science.gov (United States)

    Xu, Kui; Boas, David A; Sakadžić, Sava; LaManna, Joseph C

    2017-01-01

    Key to the understanding of the principles of physiological and structural acclimatization to changes in the balance between energy supply (represented by substrate and oxygen delivery, and mitochondrial oxidative phosphorylation) and energy demand (initiated by neuronal activity) is to determine the controlling variables, how they are sensed and the mechanisms initiated to maintain the balance. The mammalian brain depends completely on continuous delivery of oxygen to maintain its function. We hypothesized that tissue oxygen is the primary sensed variable. In this study two-photon phosphorescence lifetime microscopy (2PLM) was used to determine and define the tissue oxygen tension field within the cerebral cortex of mice to a cortical depth of between 200-250 μm under normoxia and acute hypoxia (FiO 2  = 0.10). High-resolution images can provide quantitative distributions of oxygen and intercapillary oxygen gradients. The data are best appreciated by quantifying the distribution histogram that can then be used for analysis. For example, in the brain cortex of a mouse, at a depth of 200 μm, tissue oxygen tension was mapped and the distribution histogram was compared under normoxic and mild hypoxic conditions. This powerful method can provide for the first time a description of the delivery and availability of brain oxygen in vivo.

  15. Handling and assembling of low-density foam structures fabricated by two-photon polymerization

    Science.gov (United States)

    Stein, O.; Liu, Y.; Streit, J.; Cahayag, R.; Lu, Y.; Petta, N.

    2017-08-01

    Low-density foam targets for laser induced shock wave propagation experiments were produced via laser direct writing from polymeric materials. These targets were designed with dimensions of 2.0X0.25X0.3mm with a density of 100mg/cm3 and included a fully polymerized ablation layer, 15μm thick, written contiguously with the low density material in a single fabrication step. We developed a unique protocol in order to assist in the release and harvest of the foam targets from the glass substrate on which they were fabricated. The fabrication process, as well as the assembly and handling of these delicate brittle samples is described in this paper, demonstrating the flexibility, versatility and efficiency of two photon polymerization as fabrication technique that may complement conventional approaches for low density materials fabrication. An ongoing research effort is being conducted in order to reduce to the minimum the content of stitching defects between the target's building blocks.

  16. Measurement of drug-target engagement in live cells by two-photon fluorescence anisotropy imaging.

    Science.gov (United States)

    Vinegoni, Claudio; Fumene Feruglio, Paolo; Brand, Christian; Lee, Sungon; Nibbs, Antoinette E; Stapleton, Shawn; Shah, Sunil; Gryczynski, Ignacy; Reiner, Thomas; Mazitschek, Ralph; Weissleder, Ralph

    2017-07-01

    The ability to directly image and quantify drug-target engagement and drug distribution with subcellular resolution in live cells and whole organisms is a prerequisite to establishing accurate models of the kinetics and dynamics of drug action. Such methods would thus have far-reaching applications in drug development and molecular pharmacology. We recently presented one such technique based on fluorescence anisotropy, a spectroscopic method based on polarization light analysis and capable of measuring the binding interaction between molecules. Our technique allows the direct characterization of target engagement of fluorescently labeled drugs, using fluorophores with a fluorescence lifetime larger than the rotational correlation of the bound complex. Here we describe an optimized protocol for simultaneous dual-channel two-photon fluorescence anisotropy microscopy acquisition to perform drug-target measurements. We also provide the necessary software to implement stream processing to visualize images and to calculate quantitative parameters. The assembly and characterization part of the protocol can be implemented in 1 d. Sample preparation, characterization and imaging of drug binding can be completed in 2 d. Although currently adapted to an Olympus FV1000MPE microscope, the protocol can be extended to other commercial or custom-built microscopes.

  17. Autonomous T cell trafficking examined in vivo with intravital two-photon microscopy

    Science.gov (United States)

    Miller, Mark J.; Wei, Sindy H.; Cahalan, Michael D.; Parker, Ian

    2003-03-01

    The recirculation of T cells between the blood and secondary lymphoid organs requires that T cells are motile and sensitive to tissue-specific signals. T cell motility has been studied in vitro, but the migratory behavior of individual T cells in vivo has remained enigmatic. Here, using intravital two-photon laser microscopy, we imaged the locomotion and trafficking of naïve CD4+ T cells in the inguinal lymph nodes of anesthetized mice. Intravital recordings deep within the lymph node showed T cells flowing rapidly in the microvasculature and captured individual homing events. Within the diffuse cortex, T cells displayed robust motility with an average velocity of 11 μm·min1. T cells cycled between states of low and high motility roughly every 2 min, achieving peak velocities >25 μm·min1. An analysis of T cell migration in 3D space revealed a default trafficking program analogous to a random walk. Our results show that naïve T cells do not migrate collectively, as they might under the direction of pervasive chemokine gradients. Instead, they appear to migrate as autonomous agents, each cell taking an independent trafficking path. Our results call into question the role of chemokine gradients for basal T cell trafficking within T cell areas and suggest that antigen detection may result from a stochastic process through which a random walk facilitates contact with antigen-presenting dendritic cells.

  18. Phosphorescent Oxygen Sensor with Dendritic Protection and Two-Photon Absorbing Antenna

    Science.gov (United States)

    Briñas, Raymond P.; Troxler, Thomas; Hochstrasser, Robin M.; Vinogradov, Sergei A.

    2008-01-01

    Imaging oxygen in 3D with submicron spatial resolution can be made possible by combining phosphorescence quenching technique with multiphoton laser scanning microscopy. Because Pt and Pd porphyrin-based phosphorescent dyes, traditionally used as phosphors in biological oxygen measurements, exhibit extremely low two-photon absorption (2PA) cross-sections, we designed a nanosensor for oxygen, in which a 2P absorbing antenna is coupled to a metalloporphyrin core via intramolecular energy transfer (ET) with the purpose of amplifying the 2PA induced phosphorescence of the metalloporphyrin. The central component of the device is a polyfunctionalized Pt porphyrin, whose triplet state emission at ambient temperatures is strong, occurs in the near infrared and is sensitive to O2. The 2PA chromophores are chosen in such a way that their absorption is maximal in the near infrared (NIR) window of tissue (e.g., 700−900 nm), while their fluorescence is overlapped with the absorption band(s) of the core metalloporphyrin, ensuring an efficient antenna-core resonance ET. The metalloporphyrin-antenna construct is embedded inside the protecting dendritic jacket, which isolates the core from interactions with biological macromolecules, controls diffusion of oxygen and makes the entire sensor water-soluble. Several Pt porphyrin-coumarin based sensors were synthesized and their photophyics studied to evaluate the proposed design. PMID:16104764

  19. Biexcitonic photocurrent induced by two-photon process at a telecommunication band

    International Nuclear Information System (INIS)

    Kodera, Tetsuo; Miyazawa, Toshiyuki; Kumagai, Naoto; Watanabe, Katsuyuki; Suzuki, Ayako; Takagi, Hiroyuki; Nakaoka, Toshihiro; Arakawa, Yasuhiko

    2009-01-01

    We report on photocurrent (PC) measurements of biexciton in a single self-assembled InAs quantum dot (QD) at a telecommunication wavelength of 1.3μm. We use shadow mask technique on an n-i Schottky photodiode structure with QDs to excite a single QD resonantly. Coherent pulse excitation is realized in two types of setups utilizing (i) an optical parametric oscillator and (ii) a stable semiconductor laser diode. In both setups we observe the biexcitonic PC peaks induced by a coherent two-photon process. Especially in the latter setups, the narrower pulse linewidth in energy provides a clearer biexcitonic PC peak because of reduced unwanted excitation. We estimate the binding energy ΔE B of our telecom-band biexciton to be 0.9 meV from the splitting between excitonic and biexcitonic resonances. The result suggests our telecom-band exciton-biexciton system is a good candidate for the building block of fiber-based controlled-rotation quantum logic operation. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Ultimate use of two-photon fluorescence microscopy to map orientational behavior of fluorophores.

    Science.gov (United States)

    Ferrand, Patrick; Gasecka, Paulina; Kress, Alla; Wang, Xiao; Bioud, Fatma-Zohra; Duboisset, Julien; Brasselet, Sophie

    2014-06-03

    The orientational distribution of fluorophores is an important reporter of the structure and function of their molecular environment. Although this distribution affects the fluorescence signal under polarized-light excitation, its retrieval is limited to a small number of parameters. Because of this limitation, the need for a geometrical model (cone, Gaussian, etc.) to effect such retrieval is often invoked. In this work, using a symmetry decomposition of the distribution function of the fluorescent molecules, we show that polarized two-photon fluorescence based on tunable linear dichroism allows for the retrieval of this distribution with reasonable fidelity and without invoking either an a priori knowledge of the system to be investigated or a geometrical model. We establish the optimal level of detail to which any distribution can be retrieved using this technique. As applied to artificial lipid vesicles and cell membranes, the ability of this method to identify and quantify specific structural properties that complement the more traditional molecular-order information is demonstrated. In particular, we analyze situations that give access to the sharpness of the angular constraint, and to the evidence of an isotropic population of fluorophores within the focal volume encompassing the membrane. Moreover, this technique has the potential to address complex situations such as the distribution of a tethered membrane protein label in an ordered environment. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.