Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Elliott, Drew; Scime, Earl; Short, Zachary, E-mail: zdshort@mix.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26056 (United States)

2016-11-15

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.

Double-mode Two-photon Absorption and Enhanced Photon Antibunching Due to Interference

Science.gov (United States)

Bandilla, A.; Ritze, H.-H.

Inspired by results of interfering signal and idler from a nondegenerate parametric amplifier we investigate the photon statistics of the resulting field after interference of two components subjected to double-mode two-photon absorption. This absorption process leads to a strong correlation of the participating modes, which can be used to generate fields with photon antibunching in interference experiments. In addition the photon number can be made small, which produces enhanced antibunching.Translated AbstractZwei-Photonen-Absorption aus zwei Moden und durch Interferenz verstärktes photon antibunchingDie quantenmechanische Betrachtung der Interferenz führt zu neuen Ergebnissen, wenn Felder ohne klassisches Analogon betrachtet werden. Insbesondere ergibt sich durch die Reduktion der Photonenzahl durch Interferenz eine effektive Verstärkung des Photon Antibunching, wie von den Verfassern in vorhergehenden Arbeiten gezeigt wurde. Die vorliegende Untersuchung betrachtet die Interferenz von zwei korrelierten Moden, wobei die Korrelation durch Zwei-Photonen-Absorption aus den beiden Moden zustande kommt. In jeder einzelnen Mode ergibt sich lediglich ein gewisses Bunching, wenn man mit kohärentem Licht in beiden Moden beginnt. Es wird die Interferenz der Feldstärke-Komponenten in bestimmten Polarisationsrichtungen untersucht. Zur Vereinfachung wird in den betrachteten Moden die gleiche Anfangsphotonenzahl vorausgesetzt und der Analysator auf minimale Transmittanz gebracht. Das eigentliche Signal entsteht dann durch Einführung einer endlichen Phasenverschiebung zwischen den beiden Moden. Dieses Signal zeigt Antibunching und kann in seiner Intensität beliebig variiert werden, was wegen des (1/n)-Charakters des Antibunching zu seiner Verstärkung führt. Ferner wird gezeigt, daß die zunächst für zwei linear polarisierte Moden durchgeführte Rechnung auf zwei zirkulare Moden sowie auf zwei gegenläufige Strahlen bei der dopplerfreien Zwei-Quanten-Absorption �

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

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.

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....

All-optical femtosecond switch using two-photon absorption

International Nuclear Information System (INIS)

Yavuz, D. D.

2006-01-01

Utilizing a two-photon absorption scheme in an alkali-metal vapor cell, we suggest a technique where a strong laser beam switches off another laser beam of different wavelength in femtosecond time scales

Enhancement of intermediate-field two-photon absorption by rationally shaped femtosecond pulses

International Nuclear Information System (INIS)

Chuntonov, Lev; Rybak, Leonid; Gandman, Andrey; Amitay, Zohar

2008-01-01

We extend the powerful frequency-domain analysis of femtosecond two-photon absorption to the intermediate-field regime of considerable absorption yields, where additionally to the weak-field nonresonant two-photon transitions also four-photon transitions play a role. Consequently, we rationally find that the absorption is enhanced over the transform-limited pulse by any shaped pulse having a spectral phase that is antisymmetric around one-half of the transition frequency and a spectrum that is asymmetric around it (red or blue detuned according to the system). The enhancement increases as the field strength increases. The theoretical results for Na are verified experimentally

Mid-infrared two-photon absorption in an extended-wavelength InGaAs photodetector

Science.gov (United States)

Piccardo, Marco; Rubin, Noah A.; Meadowcroft, Lauren; Chevalier, Paul; Yuan, Henry; Kimchi, Joseph; Capasso, Federico

2018-01-01

We investigate the nonlinear optical response of a commercial extended-wavelength In0.81Ga0.19As uncooled photodetector. Degenerate two-photon absorption in the mid-infrared range is observed using a quantum cascade laser emitting at λ = 4.5 μm as the excitation source. From the measured two-photon photocurrent signal, we extract a two-photon absorption coefficient β(2) = 0.6 ± 0.2 cm/MW, in agreement with the theoretical value obtained from the Eg-3 scaling law. Considering the wide spectral range covered by extended-wavelength InxGa1-xAs alloys, this result holds promise for applications based on two-photon absorption for this family of materials at wavelengths between 1.8 and 5.6 μm.

Total photon absorption

International Nuclear Information System (INIS)

Carlos, P.

1985-01-01

Experimental methods using real photon beams for measurements of total photonuclear absorption cross section σ(Tot : E/sub γ/) are recalled. Most recent σ(Tot : E/sub γ/)results for complex nuclei and in the nucleon resonance region are presented

pH-Induced Modulation of One- and Two-Photon Absorption Properties in a Naphthalene-Based Molecular Probe.

Science.gov (United States)

Murugan, N Arul; Kongsted, Jacob; Ågren, Hans

2013-08-13

Presently, there is a great demand for small probe molecules that can be used for two-photon excitation microscopy (TPM)-based monitoring of intracellular and intraorganelle activity and pH. The candidate molecules should ideally possess a large two-photon absorption cross section with optical properties sensitive to pH changes. In the present work, we investigate the potential of a methoxy napthalene (MONAP) derivative for its suitability to serve as a pH sensor using TPM. Using an integrated approach rooted in hybrid quantum mechanics/molecular mechanics, the structures, dynamics, and the one- and two-photon properties of the probe in dimethylformamide solvent are studied. It is found that the protonated form is responsible for the optical property of MONAP at moderately low pH, for which the calculated pH-induced red shift is in good agreement with experiments. A 2-fold increase in the two-photon absorption cross section in the IR region of the spectrum is predicted for the moderately low pH form of the probe, suggesting that this can be a potential probe for pH monitoring of living cells. We also propose some design principles aimed at obtaining control of the absorption spectral range of the probe by structural tuning. Our work indicates that the integrated approach employed is capable of capturing the pH-induced changes in structure and optical properties of organic molecular probes and that such in silico tools can be used to draw structure-property relationships to design novel molecular probes suitable for a specific application.

The development of efficient two-photon singlet oxygen sensitizers

DEFF Research Database (Denmark)

Nielsen, Christian Benedikt

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...... for making efficient two-photon singlet oxygen sensitizers were then constructed from these results. Charge-transfer in the excited state of the prepared molecules was shown to play a pivotal role in the generationof singlet oxygen. This was established through studies of substituent effects on both...... 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...

Inhibition of two-photon absorption in a three-level system with a pair of bichromatic fields

International Nuclear Information System (INIS)

Zou Jinhua; Hu Xiangming; Cheng Guangling; Li Xing; Du Dan

2005-01-01

We study two-photon absorption in a three-level ladder atomic system driven by a pair of bichromatic fields of equal frequency differences. The high-frequency component of one bichromatic field and the low-frequency component of the other are on two-photon resonance. The transition probability is calculated by employing the method of harmonic expansion and matrix inversion. Unexpectedly, when the sums of the phases of the different pairs of field components on the two-photon resonance are equal to each other, two-photon absorption is dramatically suppressed and the atomic system becomes transparent against two-photon absorption. Physically, due to dynamical Stark splitting, the two-photon transitions induced by the different pairs of field components experience different dressed states with phase difference of π. As a result, destructive interference occurs between the two pathways and leads to the inhibition of two-photon absorption

Inhibition of two-photon absorption due to dipole-dipole interaction in nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 (Canada)], E-mail: msingh@uwo.ca

2008-07-21

We have investigated the inhibition of two-photon absorption in photonic crystals doped with an ensemble of four-level nanoparticles. The particles are interacting with one another by the dipole-dipole interaction. Dipoles in nanoparticles are induced by a selected transition. Numerical simulations have been performed for an isotropic photonic crystal. Interesting phenomena have been predicted such as the inhibition of the two-photon absorption due to the dipole-dipole interaction. It has also been found that the inhibition effect can be switched on and off by tuning a decay resonance energy within the energy band of the crystal. A theory of dressed states has been used to explain the results.

Optical Kerr effect and two-photon absorption in monolayer black phosphorus

Science.gov (United States)

Margulis, Vl A.; Muryumin, E. E.; Gaiduk, E. A.

2018-05-01

A theoretical treatment of nonlinear refraction and two-photon absorption is presented for a novel two-dimensional material, monolayer black phosphorus (or phosphorene), irradiated by a normally incident and linearly polarized coherent laser beam of frequency ω. It is found that both the nonlinear refractive index n 2(ω) and the two-photon absorption coefficient α 2(ω) of phosphorene depend upon the polarization of the radiation field relative to phosphorene’s crystallographic axes. For the two principal polarization directions considered—viz, the armchair ({ \\mathcal A }{ \\mathcal C }) and zigzag ({ \\mathcal Z }{ \\mathcal Z }), the calculated values of n 2 and α 2 are distinguished by the order of their magnitude, with the n 2 and α 2 values being greater for the { \\mathcal A }{ \\mathcal C } direction. Furthermore, for almost all the incident photon energies below the fundamental absorption edge, except its neighborhood, the signs of n 2 as well as α 2 for the { \\mathcal A }{ \\mathcal C } and { \\mathcal Z }{ \\mathcal Z } polarization directions are opposed to each other. Also, for both the directions, the change of sign of n 2 is predicted to occur in the way between the two-photon absorption edge and the fundamental absorption edge, as well as in the near vicinity of the latter, where the Kerr nonlinearity has a pronounced resonant character and the magnitude of n 2 for the { \\mathcal A }{ \\mathcal C } and { \\mathcal Z }{ \\mathcal Z } polarization directions reaches its largest positive values of the order of 10‑9 and 10‑10 cm2 W‑1, respectively. The implications of the findings for practical all-optical switching applications are discussed.

N-Annulated perylene-substituted and fused porphyrin dimers with intense near-infrared one-photon and two-photon absorption

KAUST Repository

Luo, Jie

2015-01-21

Fusion of two N-annulated perylene (NP) units with a fused porphyrin dimer along the S0-S1 electronic transition moment axis has resulted in new near-infrared (NIR) dyes 1a/1b with very intense absorption (ε>1.3×105M-1cm-1) beyond 1250nm. Both compounds displayed moderate NIR fluorescence with fluorescence quantum yields of 4.4×10-6 and 6.0×10-6 for 1a and 1b, respectively. The NP-substituted porphyrin dimers 2a/2b have also been obtained by controlled oxidative coupling and cyclodehydrogenation, and they showed superimposed absorptions of the fused porphyrin dimer and the NP chromophore. The excited-state dynamics of all of these compounds have been studied by femtosecond transient absorption measurements, which revealed porphyrin dimer-like behaviour. These new chromophores also exhibited good nonlinear optical susceptibility with large two-photon absorption cross-sections in the NIR region due to extended π-conjugation. Time-dependent density functional theory calculations have been performed to aid our understanding of their electronic structures and absorption spectra.

Pressure broadening of atomic oxygen two-photon absorption laser induced fluorescence

NARCIS (Netherlands)

Marinov, D.; Drag, C.; Blondel, C.; Guaitella, O.; Golda, J.; Klarenaar, B.L.M.; Engeln, R.A.H.; Schulz-von der Gathen, V.; Booth, J.-P.

2016-01-01

Atomic oxygen, considered to be a determining reactant in plasma applications at ambient pressure, is routinely detected by two-photon absorption laser induced fluorescence (TALIF). Here, pressure broadening of the (2p 4 3 P 2  →  3p 3 P J=0,1,2) two-photon transition in oxygen atoms was

Two-Photon Absorbing Molecules as Potential Materials for 3D Optical Memory

Directory of Open Access Journals (Sweden)

Kazuya Ogawa

2014-01-01

Full Text Available In this review, recent advances in two-photon absorbing photochromic molecules, as potential materials for 3D optical memory, are presented. The investigations introduced in this review indicate that 3D data storage processing at the molecular level is possible. As 3D memory using two-photon absorption allows advantages over existing systems, the use of two-photon absorbing photochromic molecules is preferable. Although there are some photochromic molecules with good properties for memory, in most cases, the two-photon absorption efficiency is not high. Photochromic molecules with high two-photon absorption efficiency are desired. Recently, molecules having much larger two-photon absorption cross sections over 10,000 GM (GM= 10−50 cm4 s molecule−1 photon−1 have been discovered and are expected to open the way to realize two-photon absorption 3D data storage.

Broadband Two-Photon Absorption Characteristics of Highly Photostable Fluorenyl-Dicyanoethylenylated [60]Fullerene Dyads

Directory of Open Access Journals (Sweden)

Seaho Jeon

2016-05-01

Full Text Available We synthesized four C60-(light-harvesting antenna dyads C60 (>CPAF-Cn (n = 4, 9, 12, or 18 1-Cn for the investigation of their broadband nonlinear absorption effect. Since we have previously demonstrated their high function as two-photon absorption (2PA materials at 1000 nm, a different 2PA wavelength of 780 nm was applied in the study. The combined data taken at two different wavelength ranges substantiated the broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial π-conjugation between the C60 > cage and CPAF-Cn moieties, via endinitrile tautomeric resonance, giving a resonance state with enhanced molecular conjugation. This transient state could increase its 2PA and excited-state absorption at 800 nm. In addition, a trend of concentration-dependent 2PA cross-section (σ2 and excited-state absorption magnitude was detected showing a higher σ value at a lower concentration that was correlated to increasing molecular separation with less aggregation for dyads C60(>CPAF-C18 and C60(>CPAF-C9, as better 2PA and excited-state absorbers.

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

Novel triphenylamine-cored two-photon absorbing dyes for labeling of biomolecules

International Nuclear Information System (INIS)

Xiao Haibo; Mei Chong; Wang Yaochuan; Li, Hui; Qian Shixiong; Yin Hongyao; Xu Zhisong

2011-01-01

Highlights: → Two novel triphenylamine-cored chromophores were synthesized. → These two dyes have sizable two-photon absorption cross-section at 800 nm. → They possess reasonable water solubility and are suitable as labels in aqueous biological environments. → These dyes have strong chelating ability. → They display a large set of reactivity for coupling to biomolecules. - Abstract: Two novel, V-shaped and Y-shaped dipicolinate derivatives branched from triphenylamine, {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinyl]}-N-phenyl-N-{4- [(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinylphenyl]}aniline (1) and {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl) vinyl]}-N,N-bis {4-[(E)-2-(2,6-dimethoxycarbonyl pyridin-4-yl)vinylphenyl]}aniline (2) were synthesized. These compounds were designed for large two-photon absorption and in particular for labeling of biomolecules. Their linear absorption, fluorescence properties and their two-photon absorption properties as well as two-photon fluorescence cell imaging were examined. When excited at 800 nm, the two-photon absorption cross-section values of chromophores 1 and 2 in THF were 208 GM, 376 GM, respectively. These two-photon absorbing dyes possess reasonable water solubility, strong chelating ability and display a large set of reactivity for coupling to biomolecules, which are apparently due to the two methoxycarbonyl groups in pyridine ring. This work suggests that chromophores 1 and 2 are promising labels potentially applicable for the tracking of biomolecules using two-photon scanning microscopy.

Study the multi-photon absorption process in two types of molecules

International Nuclear Information System (INIS)

Al-azawi, H.R.

1986-01-01

The aim of the present work was to study the multi-photon absorption process in two types of molecules; spherical top such as SF 6 molecules and assymetric top such as CHOOH and C 2 H 4 molecules. This work also aimed to study the effect of buffer gas pressure (Ar), which is transparent to the infrared (IR) laser on the multiphoton absorption of both types of molecules. A pulsed (TEA) CO 2 laser was used as a source which generates multi-lines in the IR-region of the spectrum and an optoacoustic detector was used to detect the energy absorbed by the molecules. In this study, the relaxation process was found to be faster in the heavy molecules than that in the light ones. A limit in the Ar pressure was observed. Below this limit, the gas acted as an active buffer gas and above it, the multi-photon absorption process was quenched. This work also aimed to study the multi-photon absorption spectrum for the CHOOH molecules in the range (1067-1090 cm -1 ). This spectrum was found to be consistent with the linear absorption spectrum obtained for the same range. The density of the vibrational states as a function of the vibrational energy was studied for the molecules SF 6 , CHOOH and C 2 H 4 . The results were used to interpret (i) the difference in the energy absorbed by difference molecules at the same energy density and (ii) the non-linearity in the multi-photon absorption for CHOOH molecules. 1 tab.; 40 figs.; 70 refs

XCOM: Photon Cross Sections Database

Science.gov (United States)

SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.

Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation

Science.gov (United States)

Miyamoto, Yuki; Hara, Hideaki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

2018-01-01

We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.

Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

International Nuclear Information System (INIS)

Xu, Shuwu; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong; Huang, Yunxia

2015-01-01

We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye. (paper)

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

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...

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

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.

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

Exciton absorption of entangled photons in semiconductor quantum wells

Science.gov (United States)

Rodriguez, Ferney; Guzman, David; Salazar, Luis; Quiroga, Luis; Condensed Matter Physics Group Team

2013-03-01

The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers. Research funds from Facultad de Ciencias, Universidad de los Andes

On-demand single-photon state generation via nonlinear absorption

International Nuclear Information System (INIS)

Hong Tao; Jack, Michael W.; Yamashita, Makoto

2004-01-01

We propose a method for producing on-demand single-photon states based on collision-induced exchanges of photons and unbalanced linear absorption between two single-mode light fields. These two effects result in an effective nonlinear absorption of photons in one of the modes, which can lead to single-photon states. A quantum nonlinear attenuator based on such a mechanism can absorb photons in a normal input light pulse and terminate the absorption at a single-photon state. Because the output light pulses containing single photons preserve the properties of the input pulses, we expect this method to be a means for building a highly controllable single-photon source

Multi-photon absorption limits to heralded single photon sources

Science.gov (United States)

Husko, Chad A.; Clark, Alex S.; Collins, Matthew J.; De Rossi, Alfredo; Combrié, Sylvain; Lehoucq, Gaëlle; Rey, Isabella H.; Krauss, Thomas F.; Xiong, Chunle; Eggleton, Benjamin J.

2013-01-01

Single photons are of paramount importance to future quantum technologies, including quantum communication and computation. Nonlinear photonic devices using parametric processes offer a straightforward route to generating photons, however additional nonlinear processes may come into play and interfere with these sources. Here we analyse spontaneous four-wave mixing (SFWM) sources in the presence of multi-photon processes. We conduct experiments in silicon and gallium indium phosphide photonic crystal waveguides which display inherently different nonlinear absorption processes, namely two-photon (TPA) and three-photon absorption (ThPA), respectively. We develop a novel model capturing these diverse effects which is in excellent quantitative agreement with measurements of brightness, coincidence-to-accidental ratio (CAR) and second-order correlation function g(2)(0), showing that TPA imposes an intrinsic limit on heralded single photon sources. We build on these observations to devise a new metric, the quantum utility (QMU), enabling further optimisation of single photon sources. PMID:24186400

Rotational averaging of multiphoton absorption cross sections

Energy Technology Data Exchange (ETDEWEB)

Friese, Daniel H., E-mail: daniel.h.friese@uit.no; Beerepoot, Maarten T. P.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, University of Tromsø — The Arctic University of Norway, N-9037 Tromsø (Norway)

2014-11-28

Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

Quantum interference between multi photon absorption pathways in organic solid

International Nuclear Information System (INIS)

Rebane, A.; Christensson, N.; Drobizhev, M.; Stepanenko, Y.; Spangler, C.W.

2007-01-01

We demonstrate spatial interference fringe pattern by simultaneous one- and three-photon absorption of UV and near-IR femtosecond pulses in thin film organic solid at room temperature. We use organic dendrimers that are specially designed to have strong fluorescence and very large three-photon absorption cross-section. High fringe visibility allows the quantum interference to be observed by eye

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.

Polarization control of multi-photon absorption under intermediate femtosecond laser field

International Nuclear Information System (INIS)

Cheng Wenjing; Liang Guo; Wu Ping; Liu Pei; Jia Tianqing; Sun Zhenrong; Zhang Shian

2017-01-01

It has been shown that the femtosecond laser polarization modulation is a very simple and well-established method to control the multi-photon absorption process by the light–matter interaction. Previous studies mainly focused on the multi-photon absorption control in the weak field. In this paper, we further explore the polarization control behavior of multi-photon absorption process in the intermediate femtosecond laser field. In the weak femtosecond laser field, the second-order perturbation theory can well describe the non-resonant two-photon absorption process. However, the higher order nonlinear effect (e.g., four-photon absorption) can occur in the intermediate femtosecond laser field, and thus it is necessary to establish new theoretical model to describe the multi-photon absorption process, which includes the two-photon and four-photon transitions. Here, we construct a fourth-order perturbation theory to study the polarization control behavior of this multi-photon absorption under the intermediate femtosecond laser field excitation, and our theoretical results show that the two-photon and four-photon excitation pathways can induce a coherent interference, while the coherent interference is constructive or destructive that depends on the femtosecond laser center frequency. Moreover, the two-photon and four-photon transitions have the different polarization control efficiency, and the four-photon absorption can obtain the higher polarization control efficiency. Thus, the polarization control efficiency of the whole excitation process can be increased or decreased by properly designing the femtosecond laser field intensity and laser center frequency. These studies can provide a clear physical picture for understanding and controlling the multi-photon absorption process in the intermediate femtosecond laser field, and also can provide a theoretical guidance for the future experimental realization. (paper)

Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

Energy Technology Data Exchange (ETDEWEB)

Moreno, J.; Dobryakov, A. L.; Hecht, S., E-mail: sh@chemie.hu-berlin.de, E-mail: skovale@chemie.hu-berlin.de; Kovalenko, S. A., E-mail: sh@chemie.hu-berlin.de, E-mail: skovale@chemie.hu-berlin.de [Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-St. 2, 12489 Berlin (Germany); Ioffe, I. N. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Granovsky, A. A. [Firefly Project, 117593 Moscow (Russian Federation)

2015-07-14

1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.

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.

Ionization of a cesium atom by an absorption process involving two photons from a laser beam; Ionisation d'un atome de cesium par un processus d'absorption a deux photons issus d'un faisceau laser

Energy Technology Data Exchange (ETDEWEB)

Gontier, Y; Trahin, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-01-01

The expression giving the ionisation cross-section of an atom, by an absorption process involving two photons produced from a laser beam, is derived. The non-relativistic case is considered and the dipolar approximation used. The summation over the intermediate states is carried out rigorously by means of a special technique which is described in detail. A method is presented which makes it possible to obtain the numerical solution. (authors) [French] La formule donnant la section efficace d'ionisation d'un atome, par un processus d'absorption mettant en jeu deux photons issus d'un faiseau Laser, est etablie. On se place dans le cas non relativiste et Pon utilise l'approximation dipolaire. La sommation sur les etats intermediaires est effectuee rigoureusement au moyen d'une technique particuliere qui est decrite en detail. On expose une methode permettant d'obtenir la solution numerique. (auteurs)

Control of one- and two-photon absorption in a four-level atomic system by changing the amplitude and phase of a driving microwave field

International Nuclear Information System (INIS)

Hou, B P; Wang, S J; Yu, W L; Sun, W L

2005-01-01

We consider the one- and two-photon absorption spectra of a four-level Y-type atom with the two highest lying levels driven by a microwave field. We found that in the one-photon absorption case, the microwave field can lead to the probe gain, and the absorption and gain spectral structures depend strongly on the microwave field amplitude. For the two-photon absorption case, the strong microwave field can enhance the absorption. When the microwave field amplitude is reduced to a certain value, the single absorption peak in the two-photon spectrum changes into a structure of two-peak structure with different magnitudes. Moreover, the one- and two-photon absorption spectra can be modulated by the phase of the microwave field which produces a closed-loop configuration. Finally, we use the analytic solutions in terms of dressed-state basis to explain the results from our numerical calculation

Calculation of the spatial resolution in two-photon absorption spectroscopy applied to plasma diagnosis

Energy Technology Data Exchange (ETDEWEB)

Garcia-Lechuga, M. [Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47011-Valladolid (Spain); Laser Processing Group, Instituto de Óptica “Daza de Valdés,” CSIC, 28006-Madrid (Spain); Fuentes, L. M. [Departamento de Física Aplicada, Universidad de Valladolid, 47011-Valladolid (Spain); Grützmacher, K.; Pérez, C., E-mail: concha@opt.uva.es; Rosa, M. I. de la [Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47011-Valladolid (Spain)

2014-10-07

We report a detailed characterization of the spatial resolution provided by two-photon absorption spectroscopy suited for plasma diagnosis via the 1S-2S transition of atomic hydrogen for optogalvanic detection and laser induced fluorescence (LIF). A precise knowledge of the spatial resolution is crucial for a correct interpretation of measurements, if the plasma parameters to be analysed undergo strong spatial variations. The present study is based on a novel approach which provides a reliable and realistic determination of the spatial resolution. Measured irradiance distribution of laser beam waists in the overlap volume, provided by a high resolution UV camera, are employed to resolve coupled rate equations accounting for two-photon excitation, fluorescence decay and ionization. The resulting three-dimensional yield distributions reveal in detail the spatial resolution for optogalvanic and LIF detection and related saturation due to depletion. Two-photon absorption profiles broader than the Fourier transform-limited laser bandwidth are also incorporated in the calculations. The approach allows an accurate analysis of the spatial resolution present in recent and future measurements.

Calculation of the spatial resolution in two-photon absorption spectroscopy applied to plasma diagnosis

International Nuclear Information System (INIS)

Garcia-Lechuga, M.; Fuentes, L. M.; Grützmacher, K.; Pérez, C.; Rosa, M. I. de la

2014-01-01

We report a detailed characterization of the spatial resolution provided by two-photon absorption spectroscopy suited for plasma diagnosis via the 1S-2S transition of atomic hydrogen for optogalvanic detection and laser induced fluorescence (LIF). A precise knowledge of the spatial resolution is crucial for a correct interpretation of measurements, if the plasma parameters to be analysed undergo strong spatial variations. The present study is based on a novel approach which provides a reliable and realistic determination of the spatial resolution. Measured irradiance distribution of laser beam waists in the overlap volume, provided by a high resolution UV camera, are employed to resolve coupled rate equations accounting for two-photon excitation, fluorescence decay and ionization. The resulting three-dimensional yield distributions reveal in detail the spatial resolution for optogalvanic and LIF detection and related saturation due to depletion. Two-photon absorption profiles broader than the Fourier transform-limited laser bandwidth are also incorporated in the calculations. The approach allows an accurate analysis of the spatial resolution present in recent and future measurements.

Two-Photon-Absorption Scheme for Optical Beam Tracking

Science.gov (United States)

Ortiz, Gerardo G.; Farr, William H.

2011-01-01

A new optical beam tracking approach for free-space optical communication links using two-photon absorption (TPA) in a high-bandgap detector material was demonstrated. This tracking scheme is part of the canonical architecture described in the preceding article. TPA is used to track a long-wavelength transmit laser while direct absorption on the same sensor simultaneously tracks a shorter-wavelength beacon. The TPA responsivity was measured for silicon using a PIN photodiode at a laser beacon wavelength of 1,550 nm. As expected, the responsivity shows a linear dependence with incident power level. The responsivity slope is 4.5 x 10(exp -7) A/W2. Also, optical beam spots from the 1,550-nm laser beacon were characterized on commercial charge coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) imagers with as little as 13.7 microWatts of optical power (see figure). This new tracker technology offers an innovative solution to reduce system complexity, improve transmit/receive isolation, improve optical efficiency, improve signal-to-noise ratio (SNR), and reduce cost for free-space optical communications transceivers.

Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence.

Science.gov (United States)

Cruz, Carlos M; Márquez, Irene R; Mariz, Inês F A; Blanco, Victor; Sánchez-Sánchez, Carlos; Sobrado, Jesús M; Martín-Gago, José A; Cuerva, Juan M; Maçôas, Ermelinda; Campaña, Araceli G

2018-04-28

Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This system is shown to combine two-photon absorption and circularly polarized luminescence and a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity while the push-pull geometry and the extended network of sp 2 carbons are factors favoring the nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results.

Scattering and absorption differential cross sections for double ...

Indian Academy of Sciences (India)

The scattering and absorption differential cross sections for nonlinear QED process such as double photon Compton scattering have been measured as a function of independent final photon energy. The incident gamma photons are of 0.662 MeV in energy as produced by an 8 Ci137Cs radioactive source and thin ...

Optical nonlinearities of colloidal InP@ZnS core-shell quantum dots probed by Z-scan and two-photon excited emission

International Nuclear Information System (INIS)

Wawrzynczyk, Dominika; Szeremeta, Janusz; Samoc, Marek; Nyk, Marcin

2015-01-01

Spectrally resolved nonlinear optical properties of colloidal InP@ZnS core-shell quantum dots of various sizes were investigated with the Z-scan technique and two-photon fluorescence excitation method using a femtosecond laser system tunable in the range from 750 nm to 1600 nm. In principle, both techniques should provide comparable results and can be interchangeably used for determination of the nonlinear optical absorption parameters, finding maximal values of the cross sections and optimizing them. We have observed slight differences between the two-photon absorption cross sections measured by the two techniques and attributed them to the presence of non-radiative paths of absorption or relaxation. The most significant value of two-photon absorption cross section σ 2 for 4.3 nm size InP@ZnS quantum dot was equal to 2200 GM, while the two-photon excitation action cross section σ 2 Φ was found to be 682 GM at 880 nm. The properties of these cadmium-free colloidal quantum dots can be potentially useful for nonlinear bioimaging

Data reading with the aid of one-photon and two-photon luminescence in three-dimensional optical memory devices based on photochromic materials

International Nuclear Information System (INIS)

Akimov, Denis A; Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N; Fedotov, Andrei B; Magnitskiy, Sergey A; Sidorov-Biryukov, D A; Sokolyuk, N T

1998-01-01

The problem of nondestructive reading of the data stored in the interior of a photochromic sample was analysed. A comparison was made of the feasibility of reading based on one-photon and two-photon luminescence. A model was proposed for the processes of reading the data stored in photochromic molecules with the aid of one-photon and two-photon luminescence. In addition to photochromic transitions, account was taken of the transfer of populations between optically coupled transitions in molecules under the action of the exciting radiation. This model provided a satisfactory description of the kinetics of decay of the coloured form of bulk samples of spiropyran and made it possible to determine experimentally the quantum yield of the reverse photoreaction as well as the two-photon absorption cross section of the coloured form. Measurements were made of the characteristic erasure times of the data stored in a photochromic medium under one-photon and two-photon luminescence reading conditions. It was found that the use of two-photon luminescence made it possible to enhance considerably the contrast and localisation of the optical data reading scheme in three-dimensional optical memory devices. The experimental results were used to estimate the two-photon absorption cross section of the coloured form of a sample of indoline spiropyran in a polymethyl methacrylate matrix. (laser applications and other topics in quantum electronics)

Recent results on two-photon physics from Tasso and a review of measurements of the two-photon total cross section

International Nuclear Information System (INIS)

Kolanoski, H.

1983-03-01

Recent results on two-photon physics from the Tasso experiment are presented: the measurement of the two-photon production of Kanti K with the determination of the #betta##betta#-width of the f'(1515), an analysis of the angular correlations in the reaction #betta##betta#->rho 0 rho 0 ->π + π - π + π - and the observation of a narrow structure in the four pion mass spectrum around 2.1 GeV. In a separate part the experimental results on the total cross section for hadron production by two photons are reviewed. (orig.)

Preparation, one- and two-photon properties of carbazole derivatives containing nitrogen heterocyclic ring

Science.gov (United States)

Zhang, Yichi; Wang, Ping; Li, Liang; Chen, Zhimin; He, Chunying; Wu, Yiqun

Preparation of recording materials with high two-photon absorption activities is one of the important issues to superhigh- density two-photon absorption (TPA) three-dimensional (3D) optical data storage. In this paper, three new carbazole derivatives containing nitrogen heterocyclic ring with symmetric and asymmetric structures are prepared using ethylene as the π bridge between the carbazole unit and nitrogen heterocyclic ring, namely, 9-butyl-3-(2-(1,8- naphthyridin)vinyl)-carbazole (material 1), 9-butyl-3,6-bis(2-(1,8-naphthyl)vinyl)-carbazole (material 2) and 9-butyl-3,6- bis(2-(quinolin)vinyl)-carbazole (material 3). Their one photon properties including linear absorption spectra, fluorescence emission spectra, and fluorescence quantum yields are studied. The fluorescence excited by 120 fs pulse at 800 nm Ti: sapphire laser operating at 1 kHz repetition rate with different incident powers of 9-butyl-3-(2-(quinolin) vinyl)-carbazole (material 3) was investigated, and two-photon absorption cross-sections has been obtained. It is shown that material 3 containing quinoline rings as electron acceptor with symmetric structure exhibit high two-photon absorption activity. The result implies that material 3 (9-butyl-3-(2-(quinolin) vinyl)-carbazole) is a good candidate as a promising recording material for super-high-density two-photon absorption (TPA) three-dimensional (3D) optical data storage. The influence of chemical structure of the materials on the optical properties is discussed.

Ionization of a cesium atom by an absorption process involving two photons from a laser beam; Ionisation d'un atome de cesium par un processus d'absorption a deux photons issus d'un faisceau laser

Energy Technology Data Exchange (ETDEWEB)

Gontier, Y.; Trahin, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-01-01

The expression giving the ionisation cross-section of an atom, by an absorption process involving two photons produced from a laser beam, is derived. The non-relativistic case is considered and the dipolar approximation used. The summation over the intermediate states is carried out rigorously by means of a special technique which is described in detail. A method is presented which makes it possible to obtain the numerical solution. (authors) [French] La formule donnant la section efficace d'ionisation d'un atome, par un processus d'absorption mettant en jeu deux photons issus d'un faiseau Laser, est etablie. On se place dans le cas non relativiste et Pon utilise l'approximation dipolaire. La sommation sur les etats intermediaires est effectuee rigoureusement au moyen d'une technique particuliere qui est decrite en detail. On expose une methode permettant d'obtenir la solution numerique. (auteurs)

Transient absorption study of two-photon excitation mechanism in the LH2 complex from purple bacterium Rhodobacter sphaeroides.

Science.gov (United States)

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2012-03-08

The mechanism of two-photon excitation of a peripheral light-harvesting complex LH2 (B800-850) from purple bacterium Rhodobacter sphaeroides was explained on the basis of femtosecond transient absorption data. Fast bleaching of the B850 absorption band was measured under two-photon excitation by 1350 nm femtosecond pulses, showing fast subpicosecond arrival of excitation energy to B850 circular aggregates. Any spectral changes connected with the B800 absorption band of B800-BChl molecules were absent. A similar picture was observed under one-photon excitation of the LH2 complex by 675 nm femtosecond pulses. We believe these effects may be attributed to direct excitation of high-energy excitonic states of a B850 circular aggregate or its vibrational manifold in accordance with the model of Abe [Chem. Phys. 2001, 264, 355-363].

The study of nonlinear two-photon phenomenon in photonic crystals doped with nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 (Canada)

2007-02-28

A theory of the nonlinear two-photon absorption has been developed in a photonic crystal doped with an ensemble of four-level nanoparticles. We have considered that the nanoparticles are interacting with the photonic crystal. An expression of two-photon absorption has been obtained by using the density matrix method. The effect of the dipole-dipole interaction has also been included in the formulation. Interesting new phenomena have been predicted. For example, it is found that the inhibition of two-photon absorption can be turned on and off when the decay resonance energies of the four-level nanoparticles are moved within the energy band.

Two-Photon Absorption Properties of Gold Fluorescent Protein: A Combined Molecular Dynamics and Quantum Chemistry Study.

Science.gov (United States)

Simsek, Yusuf; Brown, Alex

2018-05-09

Molecular dynamic (MD) simulations were carried out to obtain the conformational changes of the chromophore in the gold fluorescent protein (PDB ID: 1OXF). To obtain two-photon absorption (TPA) cross-sections, time dependent density functional theory (TD-DFT) computations were performed for chromophore geometries sampled along the trajectory. The TD-DFT computations used the CAM-B3LYP functional and 6-31+G(d) basis set with the conductor-like polarizable continuum model (PCM) with parameters for water. Results showed that two dihedral angles change remarkably over the simulation time. TPA cross-sections were found to average 20 GM for the excitation to S1 between 430 and 460 nm; however, the maximal and minimal values were 35GM and 5GM, respectively. Besides the effects of the dihedrals on the spectroscopic properties, some bond lengths affected the excitation energies and the TPA cross-sections significantly (up to ±25-30%) while the effects of bond angles were smaller (±5%). Overall the present results provide insight in the effects of conformational exibility on TPA (with gold fluorescent protein as a specific example) and suggest that further experimental measurements of TPA for gold fluorescent protein should be undertaken.

Probabilistically cloning two single-photon states using weak cross-Kerr nonlinearities

International Nuclear Information System (INIS)

Zhang, Wen; Rui, Pinshu; Zhang, Ziyun; Yang, Qun

2014-01-01

By using quantum nondemolition detectors (QNDs) based on weak cross-Kerr nonlinearities, we propose an experimental scheme for achieving 1→2 probabilistic quantum cloning (PQC) of a single-photon state, secretly choosing from a two-state set. In our scheme, after a QND is performed on the to-be-cloned photon and the assistant photon, a single-photon projection measurement is performed by a polarization beam splitter (PBS) and two single-photon trigger detectors (SPTDs). The measurement is to judge whether the PQC should be continued. If the cloning fails, a cutoff is carried out and some operations are omitted. This makes our scheme economical. If the PQC is continued according to the measurement result, two more QNDs and some unitary operations are performed on the to-be-cloned photon and the cloning photon to achieve the PQC in a nearly deterministic way. Our experimental scheme for PQC is feasible for future technology. Furthermore, the quantum logic network of our PQC scheme is presented. In comparison with similar networks, our PQC network is simpler and more economical. (paper)

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.

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 .

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.

Photon-splitting cross sections

International Nuclear Information System (INIS)

Johannessen, A.M.; Mork, K.J.; Overbo, I.

1980-01-01

The differential cross section for photon splitting (scattering of one photon into two photons) in a Coulomb field, obtained earlier by Shima, has been integrated numerically to yield various differential cross sections. Energy spectra differential with respect to the energy of one of the outgoing photons are presented for several values of the primary photon energy. Selected examples of recoil momentum distributions and some interesting doubly or multiply differential cross sections are also given. Values for the total cross section are obtained essentially for all energies. The screening effect caused by atomic electrons is also taken into account, and is found to be important for high energies, as in e + e - pair production. Comparisons with various approximate results obtained by previous authors mostly show fair agreement. We also discuss the possibilities for experimental detection and find the most promising candidate to be a measurement of both photons, and their energies, at a moderately high energy

A bistriphenylamine-substituted spirobifluorene derivative exhibiting excellent nonlinearity/transparency/thermal stability trade-off and strong two-photon induced blue fluorescence

International Nuclear Information System (INIS)

Yin, Hongyao; Xiao, Haibo; Ding, Lei; Zhang, Chun; Ren, Aiming; Li, Bo

2015-01-01

A spirobifluorene-bridged donor/donor chromophore, 2,7-bis-(4-(N,N-diphenylamino)phen-1-yl)-9,9′-spirobifluorene (SPF-TP), was found to combine excellent transparency in the near UV–visible region (λ cut-off  ≤ 420 nm), large two-photon absorption cross-section (4.5 × 10 3 GM) and high thermal stability (T d  = 501 °C). In comparison to the reported two-photon absorption molecules, SPF-TP represents the best thermal stability so far described in the literature. The main electronic factors explaining the high two-photon absorption activities of SPF-TP were analyzed by theoretical calculations. Cyclic voltammograms were employed to explore the causes of the excellent transparency of SPF-TP. It was found that the spiroconjugation effect is responsible for the excellent nonlinearity/transparency/thermal stability trade-off in SPF-TP. In addition, SPF-TP is also a good two-photon induced blue fluorescent material with high fluorescence quantum yield (Φ = 0.90, in THF). - Highlights: • We report a molecule exhibiting excellent transparency. • The two-photon absorption cross-section is as large as 4.5 × 10 3 GM. • The molecule exhibits excellent thermal stability. • The molecule is a good two-photon induced blue fluorescent material. • The spiroconjugation effect explains the excellent properties

A bistriphenylamine-substituted spirobifluorene derivative exhibiting excellent nonlinearity/transparency/thermal stability trade-off and strong two-photon induced blue fluorescence

Energy Technology Data Exchange (ETDEWEB)

Yin, Hongyao [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Ding, Lei [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Zhang, Chun; Ren, Aiming [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Li, Bo [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241 (China)

2015-02-01

A spirobifluorene-bridged donor/donor chromophore, 2,7-bis-(4-(N,N-diphenylamino)phen-1-yl)-9,9′-spirobifluorene (SPF-TP), was found to combine excellent transparency in the near UV–visible region (λ{sub cut-off} ≤ 420 nm), large two-photon absorption cross-section (4.5 × 10{sup 3}GM) and high thermal stability (T{sub d} = 501 °C). In comparison to the reported two-photon absorption molecules, SPF-TP represents the best thermal stability so far described in the literature. The main electronic factors explaining the high two-photon absorption activities of SPF-TP were analyzed by theoretical calculations. Cyclic voltammograms were employed to explore the causes of the excellent transparency of SPF-TP. It was found that the spiroconjugation effect is responsible for the excellent nonlinearity/transparency/thermal stability trade-off in SPF-TP. In addition, SPF-TP is also a good two-photon induced blue fluorescent material with high fluorescence quantum yield (Φ = 0.90, in THF). - Highlights: • We report a molecule exhibiting excellent transparency. • The two-photon absorption cross-section is as large as 4.5 × 10{sup 3}GM. • The molecule exhibits excellent thermal stability. • The molecule is a good two-photon induced blue fluorescent material. • The spiroconjugation effect explains the excellent properties.

Calculation of the 1s-2s two-photon excitation cross-section in atomic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Celik, G.; Celik, E.; Kilic, H.S. [Selcuk Univ., Dept. of Physics, Faculty of Arts and Science (Turkey)

2008-12-15

The two-photon excitation cross-section of atomic hydrogen is calculated using explicit summation over intermediate states within the framework of dipole approximation. The matrix element for two-photon excitation is transformed into finite sums, consisting of the product of a radial and angular part. Nine intermediate states are employed in the calculation of the transition matrix element. The two-photon excitation cross-section obtained for the transition 1s{sup 2}S{sub 1/2}-2s{sup 2}S{sub 1/2} in atomic hydrogen is in good agreement with the literature. (authors)

Calculation of the 1s-2s two-photon excitation cross-section in atomic hydrogen

International Nuclear Information System (INIS)

Celik, G.; Celik, E.; Kilic, H.S.

2008-01-01

The two-photon excitation cross-section of atomic hydrogen is calculated using explicit summation over intermediate states within the framework of dipole approximation. The matrix element for two-photon excitation is transformed into finite sums, consisting of the product of a radial and angular part. Nine intermediate states are employed in the calculation of the transition matrix element. The two-photon excitation cross-section obtained for the transition 1s 2 S 1/2 -2s 2 S 1/2 in atomic hydrogen is in good agreement with the literature. (authors)

Optical beam induced current measurements based on two-photon absorption process in 4H-SiC bipolar diodes

Energy Technology Data Exchange (ETDEWEB)

Hamad, H.; Raynaud, C.; Bevilacqua, P.; Tournier, D.; Planson, D. [Ampère Laboratory - UMR 5005, 21, Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Vergne, B. [Franco-Allemand Institute of Saint-Louis ISL, 5, Rue du Général Cassagnou, 68300 Saint-Louis (France)

2014-02-24

Using a pulsed green laser with a wavelength of 532 nm, a duration pulse of ∼1 ns, and a mean power varying between 1 and 100 mW, induced photocurrents have been measured in 4H-SiC bipolar diodes. Considering the photon energy (2.33 eV) and the bandgap of 4H-SiC (3.2 eV), the generation of electron-hole pair by the conventional single photon absorption process should be negligible. The intensity of the measured photocurrents depends quadratically on the power beam intensity. This clearly shows that they are generated using two-photon absorption process. As in conventional OBIC (Optical Beam Induced Current), the measurements give an image of the electric field distribution in the structure under test, and the minority carrier lifetime can be extracted from the decrease of the photocurrent at the edge of the structure. The extracted minority carrier lifetime of 210 ns is consistent with results obtained in case of single photon absorption.

Optical beam induced current measurements based on two-photon absorption process in 4H-SiC bipolar diodes

International Nuclear Information System (INIS)

Hamad, H.; Raynaud, C.; Bevilacqua, P.; Tournier, D.; Planson, D.; Vergne, B.

2014-01-01

Using a pulsed green laser with a wavelength of 532 nm, a duration pulse of ∼1 ns, and a mean power varying between 1 and 100 mW, induced photocurrents have been measured in 4H-SiC bipolar diodes. Considering the photon energy (2.33 eV) and the bandgap of 4H-SiC (3.2 eV), the generation of electron-hole pair by the conventional single photon absorption process should be negligible. The intensity of the measured photocurrents depends quadratically on the power beam intensity. This clearly shows that they are generated using two-photon absorption process. As in conventional OBIC (Optical Beam Induced Current), the measurements give an image of the electric field distribution in the structure under test, and the minority carrier lifetime can be extracted from the decrease of the photocurrent at the edge of the structure. The extracted minority carrier lifetime of 210 ns is consistent with results obtained in case of single photon absorption

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

Science.gov (United States)

Eles, Philip T.; Michal, Carl A.

2005-08-01

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.

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)

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...

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.

Determining photon energy absorption parameters for different soil samples

International Nuclear Information System (INIS)

Kucuk, Nil; Cakir, Merve; Tumsavas, Zeynal

2013-01-01

The mass attenuation coefficients (μ s ) for five different soil samples were measured at 661.6, 1173.2 and 1332.5 keV photon energies. The soil samples were separately irradiated with 137 Cs and 60 Co (370 kBq) radioactive point gamma sources. The measurements were made by performing transmission experiments with a 2″ x 2″ NaI(Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of 137 Cs. The effective atomic numbers (Z eff ) and the effective electron densities (N eff ) were determined experimentally and theoretically using the obtained μ s values for the soil samples. Furthermore, the Z eff and N eff values of the soil samples were computed for the total photon interaction cross-sections using theoretical data over a wide energy region ranging from 1 keV to 15 MeV. The experimental values of the soils were found to be in good agreement with the theoretical values. Sandy loam and sandy clay loam soils demonstrated poor photon energy absorption characteristics. However, clay loam and clay soils had good photon energy absorption characteristics. (author)

Quantum-correlated two-photon transitions to excitons in semiconductor quantum wells.

Science.gov (United States)

Salazar, L J; Guzmán, D A; Rodríguez, F J; Quiroga, L

2012-02-13

The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers.

Theory of two-photon absorption by exciton states in cubic semiconductors with degenerate valence bands

International Nuclear Information System (INIS)

Nguyen Ai Viet; Nguyen Toan Thang.

1987-06-01

The coefficient of the absorption of two polarized photons is calculated for direct band gap semiconductors with degenerate valence bands. Wannier-Mott exciton states are included in both the intermediate and final states. Numerical calculations are performed for ZnSe and are compared with Sondergeld's experimental and theoretical results. (author). 11 refs, 2 tabs

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

Absorption in one-dimensional metallic-dielectric photonic crystals

International Nuclear Information System (INIS)

Yu Junfei; Shen Yifeng; Liu Xiaohan; Fu Rongtang; Zi Jian; Zhu Zhiqiang

2004-01-01

We show theoretically that the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced considerably over the corresponding constituent metal. By properly choosing the structural and material parameters, the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced by one order of magnitude in the visible and in the near infrared regions. It is found that the absorptance of such photonic crystals increases with increasing number of periods. Rules on how to obtain a absorption enhancement in a certain frequency range are discussed. (letter to the editor)

Femtosecond Two-Photon Absorption Spectroscopy of Poly(fluorene Derivatives Containing Benzoselenadiazole and Benzothiadiazole

Directory of Open Access Journals (Sweden)

Marcelo Gonçalves Vivas

2017-05-01

Full Text Available We have investigated the molecular structure and two-photon absorption (2PA properties relationship of two push–pull poly(fluorene derivatives containing benzoselenadiazole and benzothiadiazole units. For that, we have used the femtosecond wavelength-tunable Z-scan technique with a low repetition rate (1 kHz and an energy per pulse on the order of nJ. Our results show that both 2PA spectra present a strong 2PA (around 600 GM (1 GM = 1 × 10−50 cm4·s·photon−1 band at around 720 nm (transition energy 3.45 eV ascribed to the strongly 2PA-allowed 1Ag-like → mAg-like transition, characteristic of poly(fluorene derivatives. Another 2PA band related to the intramolecular charge transfer was also observed at around 900 nm (transition energy 2.75 eV. In both 2PA bands, we found higher 2PA cross-section values for the poly(fluorene containing benzothiadiazole unit. This outcome was explained through the higher charge redistribution at the excited state caused by the benzothiadiazole group as compared to the benzoselenadiazole and confirmed by means of solvatochromic Stokes shift measurements. To shed more light on these results, we employed the sum-over-states approach within the two-energy level model to estimate the maximum permanent dipole moment change related to the intramolecular charge transfer transition.

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

Angular distributions of low kinetic energy photoelectrons in one- and two-photon ionisation of rare gas atoms

International Nuclear Information System (INIS)

O'Keeffe, P; Bolognesi, P; Avaldi, L; Richter, R; Moise, A; Cleva, P De; Mihelic, A

2012-01-01

The angular distributions of electrons emitted in the photoionisation of rare gas atoms using one and two photons are presented. The one-photon results show that these differential measurements can provide complementary information on the photoionisation event with respect to the measurement of the total absorption cross section while the two photon ionization allows additional parameters to be extracted from the experiments thus permitting a more complete description of the photoionisation dynamics.

Absorption and emission properties of photonic crystals and metamaterials

International Nuclear Information System (INIS)

Peng, Lili

2007-01-01

We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.

Occurrence of two-photon absorption saturation in Ag nanocolloids, prepared by chemical reduction method

Energy Technology Data Exchange (ETDEWEB)

Rahulan, K. Mani, E-mail: krahul.au@gmail.com [Department of Physics, Anna University, Chennai (India); Ganesan, S. [Department of Physics, Anna University, Chennai (India); Aruna, P., E-mail: aruna@annauniv.edu [Department of Physics, Anna University, Chennai (India)

2012-09-01

Highlights: Black-Right-Pointing-Pointer Ag nanocolloids were synthesized via chemical reduction method. Black-Right-Pointing-Pointer The molecules of PVP play an important role in growth and agglomeration of silver nanocolloids. Black-Right-Pointing-Pointer Saturation behaviour followed by two photon absorption was responsible for good optical limiting characteristics in these nanocolloids. Black-Right-Pointing-Pointer The nonlinear optical parameters calculated from the data showed that these materials could be used as efficient optical limiters. - Abstract: Silver nanocolloids stabilized with polyvinyl pyrrolidone (PVP) have been prepared from (AgNO{sub 3}) by a chemical reduction method, involving the intermediate preparation of (Ag{sub 2}O) colloidal dispersions in the presence of sodium dodecycle sulfate as a surfactant and formaldehyde as reducing agent. The molecules of PVP play an important role in growth and agglomeration of silver nanocolloids. The formation of Ag nanocolloids was studied from the UV-vis absorption characteristics. An energy dispersive X-ray (EDX) spectrum and X-ray diffraction peak of the nanoparticles showed the highly crystalline nature of silver structure. The particle size was found to be 40 nm as analyzed from Field emission scanning electron microscopy (FESEM). The nonlinear optical and optical limiting properties of these nanoparticle dispersions were studied by using the Z-scan technique at 532 nm. Experimental results show that the Ag nanocolloids possess strong optical limiting effect, originated from absorption saturation followed by two-photon mechanism. The data show that Ag nanocolloids have great potential for nonlinear optical devices.

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.

XCOM: Photon cross sections on a personal computer

International Nuclear Information System (INIS)

Berger, M.J.; Hubbell, J.H.

1987-07-01

A computer program and data base are presented which can be used to calculate, with a personal computer, photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, in any element, compound or mixture, at energies from 1 keV to 100 GeV

Two-photon patterning of a polymer containing Y-shaped azochromophores

International Nuclear Information System (INIS)

Ambrosio, A.; Orabona, E.; Maddalena, P.; Camposeo, A.; Polo, M.; Neves, A. A. R.; Pisignano, D.; Carella, A.; Borbone, F.; Roviello, A.

2009-01-01

We report on the patterning of the free surface of azo-based polymer films by means of mass migration driven by one- or two-photon absorption. A symmetric donor-acceptor-donor structured Y-shaped azochromophore is specifically synthesized to enhance two-photon absorption in the polymer. The exposure of the polymer film to a focused laser beam results in light-driven mass migration for both one- and two-photon absorptions. Features with subdiffraction resolution (250 nm) are realized and the patterning dynamics is investigated as a function of the light dose. Furthermore, functional photonic structures, such as diffraction gratings with periods ranging between 0.5 and 2.0 μm, have been realized

Two and four photon absorption and nonlinear refraction in undoped, chromium doped and copper doped ZnS quantum dots

Science.gov (United States)

Sharma, Dimple; Malik, B. P.; Gaur, Arun

2015-12-01

The ZnS quantum dots (QDs) with Cr and Cu doping were synthesized by chemical co-precipitation method. The nanostructures of the prepared undoped and doped ZnS QDs were characterized by UV-vis spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The sizes of QDs were found to be within 3-5 nm range. The nonlinear parameters viz. Two photon absorption coefficient (β2), nonlinear refractive index (n2), third order nonlinear susceptibility (χ3) at wavelength 532 nm and Four photon absorption coefficient (β4) at wavelength 1064 nm have been calculated by Z-scan technique using nanosecond Nd:YAG laser in undoped, Cr doped and Cu doped ZnS QDs. Higher values of nonlinear parameters for doped ZnS infer that they are potential material for the development of photonics devices and sensor protection applications.

Near-IR Two-Photon Fluorescent Sensor for K(+) Imaging in Live Cells.

Science.gov (United States)

Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D

2015-08-19

A new two-photon excited fluorescent K(+) sensor is reported. The sensor comprises three moieties, a highly selective K(+) chelator as the K(+) recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (>52-fold) in detecting K(+) over other physiological metal cations. Upon binding K(+), the sensor switches from nonfluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K(+) sensing in living cells.

Two-photon emission and multiphoton absorption by atoms

International Nuclear Information System (INIS)

Mu, X.

1988-01-01

This thesis consists of investigations of two problems concerning photon-atom interactions. The first topic deals with two-photon transitions in atomic inner shells. An independent-particle model has been used to describe the two-photon transitions between different inner-shell electron states. The first relativistic self-consistent-field calculation of these transition rates in Ag, Mo, and Xe has been carried out. The theoretical results are compared with recent measurements. Good agreement with measured rates is found except in some cases where more reliable experiments still need to be done. The second topic is multiphoton multiionization of atoms. The maximum entropy principle has been employed in this theoretical investigation. A detailed statistical analysis of measured ionic charge distributions produced in strong laser pulses has been carried out. The results of this analysis indicates that the charge-state distribution is a Poissonian, rather than the binomial which prevails under infrared radiation, and hence that ionization occurs stepwise during the pulse. This result is shown to be consistent with experimental data

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.

A two photon absorption laser induced fluorescence diagnostic for fusion plasmas

Energy Technology Data Exchange (ETDEWEB)

Magee, R. M.; Galante, M. E.; McCarren, D.; Scime, E. E. [Physics Department, West Virginia University, Morgantown, West Virginia 26506 (United States); Boivin, R. L.; Brooks, N. H.; Groebner, R. J.; Hill, D. N. [General Atomics, San Diego, California 92121 (United States); Porter, G. D. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-10-15

The quality of plasma produced in a magnetic confinement fusion device is influenced to a large extent by the neutral gas surrounding the plasma. The plasma is fueled by the ionization of neutrals, and charge exchange interactions between edge neutrals and plasma ions are a sink of energy and momentum. Here we describe a diagnostic capable of measuring the spatial distribution of neutral gas in a magnetically confined fusion plasma. A high intensity (5 MW/cm{sup 2}), narrow bandwidth (0.1 cm{sup -1}) laser is injected into a hydrogen plasma to excite the Lyman {beta} transition via the simultaneous absorption of two 205 nm photons. The absorption rate, determined by measurement of subsequent Balmer {alpha} emission, is proportional to the number of particles with a given velocity. Calibration is performed in situ by filling the chamber to a known pressure of neutral krypton and exciting a transition close in wavelength to that used in hydrogen. We present details of the calibration procedure, including a technique for identifying saturation broadening, measurements of the neutral density profile in a hydrogen helicon plasma, and discuss the application of the diagnostic to plasmas in the DIII-D tokamak.

A two photon absorption laser induced fluorescence diagnostic for fusion plasmas.

Science.gov (United States)

Magee, R M; Galante, M E; McCarren, D; Scime, E E; Boivin, R L; Brooks, N H; Groebner, R J; Hill, D N; Porter, G D

2012-10-01

The quality of plasma produced in a magnetic confinement fusion device is influenced to a large extent by the neutral gas surrounding the plasma. The plasma is fueled by the ionization of neutrals, and charge exchange interactions between edge neutrals and plasma ions are a sink of energy and momentum. Here we describe a diagnostic capable of measuring the spatial distribution of neutral gas in a magnetically confined fusion plasma. A high intensity (5 MW/cm(2)), narrow bandwidth (0.1 cm(-1)) laser is injected into a hydrogen plasma to excite the Lyman β transition via the simultaneous absorption of two 205 nm photons. The absorption rate, determined by measurement of subsequent Balmer α emission, is proportional to the number of particles with a given velocity. Calibration is performed in situ by filling the chamber to a known pressure of neutral krypton and exciting a transition close in wavelength to that used in hydrogen. We present details of the calibration procedure, including a technique for identifying saturation broadening, measurements of the neutral density profile in a hydrogen helicon plasma, and discuss the application of the diagnostic to plasmas in the DIII-D tokamak.

Polarized two-photon photoselection in EGFP: Theory and experiment.

Science.gov (United States)

Masters, T A; Marsh, R J; Blacker, T S; Armoogum, D A; Larijani, B; Bain, A J

2018-04-07

In this work, we present a complete theoretical description of the excited state order created by two-photon photoselection from an isotropic ground state; this encompasses both the conventionally measured quadrupolar (K = 2) and the "hidden" degree of hexadecapolar (K = 4) transition dipole alignment, their dependence on the two-photon transition tensor and emission transition dipole moment orientation. Linearly and circularly polarized two-photon absorption (TPA) and time-resolved single- and two-photon fluorescence anisotropy measurements are used to determine the structure of the transition tensor in the deprotonated form of enhanced green fluorescent protein. For excitation wavelengths between 800 nm and 900 nm, TPA is best described by a single element, almost completely diagonal, two-dimensional (planar) transition tensor whose principal axis is collinear to that of the single-photon S 0 → S 1 transition moment. These observations are in accordance with assignments of the near-infrared two-photon absorption band in fluorescent proteins to a vibronically enhanced S 0 → S 1 transition.

Polarized two-photon photoselection in EGFP: Theory and experiment

Science.gov (United States)

Masters, T. A.; Marsh, R. J.; Blacker, T. S.; Armoogum, D. A.; Larijani, B.; Bain, A. J.

2018-04-01

In this work, we present a complete theoretical description of the excited state order created by two-photon photoselection from an isotropic ground state; this encompasses both the conventionally measured quadrupolar (K = 2) and the "hidden" degree of hexadecapolar (K = 4) transition dipole alignment, their dependence on the two-photon transition tensor and emission transition dipole moment orientation. Linearly and circularly polarized two-photon absorption (TPA) and time-resolved single- and two-photon fluorescence anisotropy measurements are used to determine the structure of the transition tensor in the deprotonated form of enhanced green fluorescent protein. For excitation wavelengths between 800 nm and 900 nm, TPA is best described by a single element, almost completely diagonal, two-dimensional (planar) transition tensor whose principal axis is collinear to that of the single-photon S0 → S1 transition moment. These observations are in accordance with assignments of the near-infrared two-photon absorption band in fluorescent proteins to a vibronically enhanced S0 → S1 transition.

Optical components based on two-photon absorption process in functionalized polymers

International Nuclear Information System (INIS)

Klein, S.; Barsella, A.; Taupier, G.; Stortz, V.; Fort, A.; Dorkenoo, K.D.

2006-01-01

We report on the fabrication of basic elements needed in optical circuits in a photopolymerizable resin, using a two-photon absorption (TPA) process to perform a selective polymerization. By taking advantage of the high spatial selectivity of the TPA approach, we can control the value of the local index of refraction in the material and realize permanent optical pathways in the bulk of photopolymerizable matrices. The computer-controlled design of such pathways allows creating optical circuits. As an example of application, optical fibers separated by millimetric distances and placed in arbitrary positions have been connected with moderate losses. Moreover, active components, such as electro-optical Mach-Zehnder interferometers, can be fabricated using photopolymers functionalized with non-linear optical chromophores, in order to be integrated in micro-optical circuits

Synthesis, structure and two-photon absorption properties of a new multi-branched compound, 1,2,4,5-tetrakis(4-pyridylvinyl)benzene

International Nuclear Information System (INIS)

Wang Lei; Tao Xutang; Yang Jiaxiang; Yu Wentao; Ren Yan; Xin Qian; Liu Zhi; Jiang Minhua

2004-01-01

A conjugated and symmetric multi-branched compound, 1,2,4,5-tetrakis(4-pyridylvinyl)benzene (TKPVB), has been synthesized and the crystal structures of TKPVB and its intermediate, 1,2,4,5-tetrakis(dimethoxyphosphorylmethyl)benzene, were determined by diffraction method. TKPVB with four units of 4-vinylpyridine moieties attached to the central benzene core presents an A-π-A general framework, where A is a π-deficient pyridine ring. The single-photon and two-photon absorption and fluorescence properties in different solvents of varying polarity have been investigated. It is also found that the one- and two-photon-induced fluorescence spectra are quite similar, which indicate that the one- and two-photon allowed-excited states are the same

Determination of the 1s-2s two-photon excitation cross-section in atomic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Bickel, G.A.; McRae, G.A

2000-07-01

Hydrogen atoms are ablated from zirconium alloys into the gas phase by a pulsed Nd:YAG laser and photo-ionized with three photons at 243 nm via the two-photon 1s {sup 2}S{sub 1/2}-2s {sup 2}S{sub 1/2} resonant transition. A determination of the effective 1s-2s two-photon excitation cross-section is necessary to quantify the hydrogen atom density in the ablation plume. A measurement of the ion signal vs photo-ionization beam energy is fitted to an expression derived from the rate equations. The temporal and spatial properties of the photo-ionization laser beam, transit of the H atoms through the beam, and detector geometry are taken into account. The effective two-photon cross-section for this experimental configuration, derived with the rate equation formalism, is 3.3 {+-} 0.8 X 10{sup -28} cm{sup 4} W{sup -1}. This compares well with the ab initio prediction of 5 {+-} 1 X 10{sup -28} cm{sup 4} W{sup -1} under these experimental conditions. (author)

Determination of the 1s-2s two-photon excitation cross-section in atomic hydrogen

International Nuclear Information System (INIS)

Bickel, G.A.; McRae, G.A.

2000-01-01

Hydrogen atoms are ablated from zirconium alloys into the gas phase by a pulsed Nd:YAG laser and photo-ionized with three photons at 243 nm via the two-photon 1s 2 S 1/2 -2s 2 S 1/2 resonant transition. A determination of the effective 1s-2s two-photon excitation cross-section is necessary to quantify the hydrogen atom density in the ablation plume. A measurement of the ion signal vs photo-ionization beam energy is fitted to an expression derived from the rate equations. The temporal and spatial properties of the photo-ionization laser beam, transit of the H atoms through the beam, and detector geometry are taken into account. The effective two-photon cross-section for this experimental configuration, derived with the rate equation formalism, is 3.3 ± 0.8 X 10 -28 cm 4 W -1 . This compares well with the ab initio prediction of 5 ± 1 X 10 -28 cm 4 W -1 under these experimental conditions. (author)

Probing the SEB Sensitive Depth of a Power MOSFET Using a Two-Photon Absorption Laser Method

Science.gov (United States)

Lauenstein, Jean-Marie; Liu, Sandra; Titus, Jeffrey L.; McMorrow, Dale; Casey, Megan C.; Buchner, Stephen P.; Warner, Jeffrey; Phan, Anthony M.; Topper, Alyson D.; Kim, Hak S.;

Relativistic photon-Maxwellian electron cross sections

International Nuclear Information System (INIS)

Wienke, B.R.; Lathrop, B.L.; Devaney, J.J.

1986-01-01

Temperature corrected cross sections, complementing the Klein-Nishina set, are developed for astrophysical, plasma, and transport applications. The set is obtained from a nonlinear least squares fit to the exact photon-Maxwellian electron cross sections, using the static formula as the asymptotic basis. Two parameters are sufficient (two decimal places) to fit the exact cross sections over a range of 0-100 keV in electron temperature, and 0-1 MeV in incident photon energy. The fit is made to the total cross sections, yet the parameters predict both total and differential scattering cross sections well. Corresponding differential energy cross sections are less accurate. An extended fit to (just) the total cross sections, over the temperature and energy range 0-5 MeV, is also described. (author)

One-, two- and three-photon spectroscopy of π-conjugated dendrimers: cooperative enhancement and coherent domains

International Nuclear Information System (INIS)

Drobizhev, M.; Rebane, A.; Suo, Z.; Spangler, C.W.

2005-01-01

We use wavelength tunable femtosecond pulses to measure intrinsic (simultaneous) two-photon absorption (2PA) and three-photon absorption (3PA) molecular cross section in two series of π-conjugated dendrimers built of identical 4,4'-bis(diphenylamino) stilbene (BDPAS) and 4,4'-bis(diphenylamino) distyrylbenzene (BDPADSB) repeat units. Record large 2PA cross sections, σ 2 =10 -46 cm 4 s are obtained for the largest second-generation BDPAS-based dendrimer, as well as zeroth-generation 4-arm BDPADSB-based dendrimer. In both series, maximum 2PA cross section increases nonlinearly with the number of π-electrons, whereas for higher generations this dependence turns to linear one. 3PA cross section also increases nonlinearly with the size of the system in the series of BDPAS-based molecules, amounting a record large value, σ 3 =10 -79 cm 6 s 2 , for the largest, second-generation dendrimer. We interpret these results in terms of direct inter-branch conjugation, which facilitates cooperative enhancement of the nonlinear-optical response. We propose a simple model which allows us to determine the effective size of coherent domains (extent of conjugation), which, in turn, determines the optimum dendrimer size for most efficient nonlinear response

Multi-mode interference revealed by two photon absorption in silicon rich SiO2 waveguides

International Nuclear Information System (INIS)

Manna, S.; Ramiro-Manzano, F.; Mancinelli, M.; Turri, F.; Pavesi, L.; Ghulinyan, M.; Pucker, G.

2015-01-01

Photoluminescence (PL) from Si nanocrystals (NCs) excited by two-photon absorption (TPA) has been observed in Si nanocrystal-based waveguides fabricated by plasma enhanced chemical vapor deposition. The TPA excited photoluminescence emission resembles the one-photon excited photoluminescence arising from inter-band transitions in the quantum confined Si nanocrystals. By measuring the non-linear transmission of waveguides, a large TPA coefficient of β up to 10 −8  cm/W has been measured at 1550 nm. These values of β depend on the Si NCs size and are two orders of magnitude larger than the bulk silicon value. Here, we propose to use the TPA excited visible PL emission as a tool to map the spatial intensity profile of the 1550 nm propagating optical modes in multimode waveguides. In this way, multimode interference has been revealed experimentally and confirmed through a finite element simulation

Polarization dependence of two-photon absorption coefficient and nonlinear susceptibility tensor in InP

International Nuclear Information System (INIS)

Matsusue, Toshio; Bando, Hiroyuki; Fujita, Shoichi; Takayama, Yusuke

2011-01-01

Two-photon absorption (TPA) effect in (001) InP is investigated using fs laser. Its dependences on wavelength and polarization are clarified by single and double beam methods with linearly polarized lights. Characteristic features are revealed and discussed with scaling law, crystal bonding and mutual relation of polarizations for double beams. The results are successfully analyzed on the basis of the third-order susceptibility tensor for comprehensive understanding of TPA effect at any polarization geometry. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bio-Inspired Photon Absorption and Energy Transfer for Next Generation Photovoltaic Devices

Science.gov (United States)

Magsi, Komal

Nature's solar energy harvesting system, photosynthesis, serves as a model for photon absorption, spectra broadening, and energy transfer. Photosynthesis harvests light far differently than photovoltaic cells. These differences offer both engineering opportunity and scientific challenges since not all of the natural photon absorption mechanisms have been understood. In return, solar cells can be a very sensitive probe for the absorption characteristics of molecules capable of transferring charge to a conductive interface. The objective of this scientific work is the advancement of next generation photovoltaics through the development and application of natural photo-energy transfer processes. Two scientific methods were used in the development and application of enhancing photon absorption and transfer. First, a detailed analysis of photovoltaic front surface fluorescent spectral modification and light scattering by hetero-structure was conducted. Phosphor based spectral down-conversion is a well-known laser technology. The theoretical calculations presented here indicate that parasitic losses and light scattering within the spectral range are large enough to offset any expected gains. The second approach for enhancing photon absorption is based on bio-inspired mechanisms. Key to the utilization of these natural processes is the development of a detailed scientific understanding and the application of these processes to cost effective systems and devices. In this work both aspects are investigated. Dye type solar cells were prepared and tested as a function of Chlorophyll (or Sodium-Copper Chlorophyllin) and accessory dyes. Forster has shown that the fluorescence ratio of Chlorophyll is modified and broadened by separate photon absorption (sensitized absorption) through interaction with nearby accessory pigments. This work used the dye type solar cell as a diagnostic tool by which to investigate photon absorption and photon energy transfer. These experiments shed

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.

3He(γ,pp)n cross sections with tagged photons below the Δ resonance energy

Science.gov (United States)

Kolb, N. R.; Feldman, G.; O'rielly, G. V.; Pywell, R. E.; Skopik, D. M.; Hackett, E. D.; Quraan, M. A.; Rodning, N. L.

1996-11-01

Cross sections have been measured for the 3He(γ,pp)n reaction with tagged photons in the range Eγ =161-208 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The protons were detected over a range of polar angles of 40°-140° and azimuthal angles of 0°-360° with an energy threshold of 40 MeV. Comparisons are made with a microscopic calculation which includes one-, two-, and three-nucleon absorption mechanisms. One- and two-nucleon processes, including final-state interactions, are unable to account for the measured cross sections. The addition of three-nucleon absorption diagrams gives roughly the right strength, but the distribution in phase space is in disagreement with the data.

Two-Photon Fluorescence Microscope for Microgravity Research

Science.gov (United States)

Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

2005-01-01

A two-photon fluorescence microscope has been developed for the study of biophysical phenomena. Two-photon microscopy is a novel form of laser-based scanning microscopy that enables three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon optical microscopy, two-photon microscopy utilizes the simultaneous nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption, so an ultra-fast pulsed laser source is typically employed. On the other hand, the critical energy threshold for two-photon absorption leads to fluorophore excitation that is intrinsically localized to the focal volume. Consequently, two-photon microscopy enables optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction (relative to one-photon optical microscopy) in photon-induced damage because of the longer excitation wavelength. This reduction is especially advantageous for in vivo studies. Relative to confocal microscopy, there is also a reduction in background fluorescence, and, because of a reduction in Rayleigh scattering, there is a 4 increase of penetration depth. The prohibitive cost of a commercial two-photon fluorescence-microscope system, as well as a need for modularity, has led to the construction of a custom-built system (see Figure 1). This system includes a coherent mode-locked titanium: sapphire laser emitting 120-fs-duration pulses at a repetition rate of 80 MHz. The pulsed laser has an average output power of 800 mW and a wavelength tuning range of 700 to 980 nm, enabling the excitation of a variety of targeted fluorophores. The output from the laser is attenuated, spatially filtered, and then directed into a confocal scanning head that has been modified to provide for side entry of the laser beam. The laser output coupler has been replaced with a dichroic filter that reflects the

New all-optical method for measuring molecular permanent dipole moment difference using two-photon absorption spectroscopy

International Nuclear Information System (INIS)

Rebane, A.; Drobizhev, M.; Makarov, N.S.; Beuerman, E.; Tillo, S.; Hughes, T.

2010-01-01

Stark effect, in combination with spectral hole burning and single-molecule spectroscopy, has been a fruitful technique to study permanent electric dipole moment of molecules in condensed phase. However, because measuring Stark shifts relies on external fields and narrow line- or hole-widths, the applicability of this method at ambient conditions required by most biological systems has remained limited. Here we demonstrate a new all-optical method for measuring the molecular dipole moment difference between ground and excited states using two-photon absorption (2PA) spectroscopy. We show that the value and orientation of the static dipole moment difference can be determined from the corresponding absolute 2PA cross-section. We use this new method to determine for the first time the strength of local electric field E loc =0.1-1.0x10 8 V/cm inside beta-barrel of Fruit series of red fluorescent proteins. Because our method does not rely on external field and is applicable in liquid solutions, it is well suited for the study of biological systems.

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...... of formamide, a uracil molecule in aqueous solution, and a set of mutants of the channelrhodopsin (ChR) protein. The first test case shows that the PERI-CC2 method is in excellent agreement with the PE-CC2 method and in good agreement with the PE-CCSD method. The uracil test case indicates that the effects...... of hydrogen bonding on the TPA of a chromophore with the nearest environment is well-described with the PERI-CC2 method. Finally, the ChR calculation shows that the PERI-CC2 method is well-suited and efficient for calculations on proteins with medium-sized chromophores....

Photon absorption of calcium phosphate-based dental biomaterials

International Nuclear Information System (INIS)

Singh, V. P.; Badiger, N. M.; Tekin, H. O.; Kara, U.; Vega C, H. R.; Fernandes Z, M. A.

2017-10-01

Effective atomic number and mass energy absorption buildup factors for four calcium phosphate-based biomaterials used in dental treatments were calculated for 0.015 to 15 MeV photons. The mass energy absorption coefficients were calculated for 0.5 to 40 mean free paths of photons. In the energy region important for dental radiology the Zeff for all studied biomaterials are larger in comparison to larger energies. In x-rays for dental radiology and the energy absorption buildup factors are low, however CbMDI bio material shows a resonance at 80 keV. (Author)

Doppler broadening and its contribution to Compton energy-absorption cross sections: An analysis of the Compton component in terms of mass-energy absorption coefficient

International Nuclear Information System (INIS)

Rao, D.V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G.E.

2002-01-01

Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1 deg. -180 deg. . Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1 deg. -180 deg., for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance

Doppler Broadening and its Contribution to Compton Energy-Absorption Cross Sections: An Analysis of the Compton Component in Terms of Mass-Energy Absorption Coefficient

Science.gov (United States)

Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G. E.

2002-09-01

Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1°-180°. Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1°-180°, for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance.

Review of Two-Photon Interactions

International Nuclear Information System (INIS)

Urner, David

2004-01-01

Presented are recent results of two-photon interactions. Topics include photon structure functions, inclusive hadron production, differential cross sections derived from tagged γγ fusion events and results in exclusive hadron production, particularly the observations of the η'c

3He(γ,pp)n cross sections with tagged photons below the Δ resonance energy

International Nuclear Information System (INIS)

Kolb, N.R.; Feldman, G.; ORielly, G.V.; Pywell, R.E.; Skopik, D.M.; Hackett, E.D.; Quraan, M.A.; Rodning, N.L.

1996-01-01

Cross sections have been measured for the 3 He(γ,pp)n reaction with tagged photons in the range E γ =161 endash 208 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The protons were detected over a range of polar angles of 40 degree endash 140 degree and azimuthal angles of 0 degree endash 360 degree with an energy threshold of 40 MeV. Comparisons are made with a microscopic calculation which includes one-, two-, and three-nucleon absorption mechanisms. One- and two-nucleon processes, including final-state interactions, are unable to account for the measured cross sections. The addition of three-nucleon absorption diagrams gives roughly the right strength, but the distribution in phase space is in disagreement with the data. copyright 1996 The American Physical Society

Molecular photosensitisers for two-photon photodynamic therapy.

Science.gov (United States)

Bolze, F; Jenni, S; Sour, A; Heitz, V

2017-11-30

Two-photon excitation has attracted the attention of biologists, especially after the development of two-photon excited microscopy in the nineties. Since then, new applications have rapidly emerged such as the release of biologically active molecules and photodynamic therapy (PDT) using two-photon excitation. PDT, which requires a light-activated drug (photosensitiser), is a clinically approved and minimally invasive treatment for cancer and for non-malignant diseases. This feature article focuses on the engineering of molecular two-photon photosensitisers for PDT, which should bring important benefits to the treatment, increase the treatment penetration depth with near-infrared light excitation, improve the spatial selectivity and reduce the photodamage to healthy tissues. After an overview of the two-photon absorption phenomenon and the methods to evaluate two-photon induced phototoxicity on cell cultures, the different classes of photosensitisers described in the literature are discussed. The two-photon PDT performed with historical one-photon sensitisers are briefly presented, followed by specifically engineered cyclic tetrapyrrole photosensitisers, purely organic photosensitisers and transition metal complexes. Finally, targeted two-photon photosensitisers and theranostic agents that should enhance the selectivity and efficiency of the treatment are discussed.

Two-Color Single-Photon Photoinitiation and Photoinhibition for Subdiffraction Photolithography

Science.gov (United States)

Scott, Timothy F.; Kowalski, Benjamin A.; Sullivan, Amy C.; Bowman, Christopher N.; McLeod, Robert R.

2009-05-01

Controlling and reducing the developed region initiated by photoexposure is one of the fundamental goals of optical lithography. Here, we demonstrate a two-color irradiation scheme whereby initiating species are generated by single-photon absorption at one wavelength while inhibiting species are generated by single-photon absorption at a second, independent wavelength. Co-irradiation at the second wavelength thus reduces the polymerization rate, delaying gelation of the material and facilitating enhanced spatial control over the polymerization. Appropriate overlapping of the two beams produces structures with both feature sizes and monomer conversions otherwise unobtainable with use of single- or two-photon absorption photopolymerization. Additionally, the generated inhibiting species rapidly recombine when irradiation with the second wavelength ceases, allowing for fast sequential exposures not limited by memory effects in the material and thus enabling fabrication of complex two- or three-dimensional structures.

A bioaccumulative cyclometalated platinum(II) complex with two-photon-induced emission for live cell imaging.

Science.gov (United States)

Koo, Chi-Kin; Wong, Ka-Leung; Man, Cornelia Wing-Yin; Lam, Yun-Wah; So, Leo King-Yan; Tam, Hoi-Lam; Tsao, Sai-Wah; Cheah, Kok-Wai; Lau, Kai-Chung; Yang, Yang-Yi; Chen, Jin-Can; Lam, Michael Hon-Wah

2009-02-02

The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.

and Three-Photon Absorption Properties of PRODAN based chemo ...

Indian Academy of Sciences (India)

Mehboob

Solvent dependent One-, Two- and Three-Photon Absorption. Properties of PRODAN based chemo-sensors. Md. Mehboob Alam, Mausumi Chattopadhyaya. Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Kolkata - 700009,. India. CONTENTS. 1) Optimized coordinates of all the systems in Gas phase and ...

Coherent single-photon absorption by single emitters coupled to 1D nanophotonic waveguides

DEFF Research Database (Denmark)

Chen, Yuntian; Wubs, Martijn; Mørk, Jesper

2012-01-01

We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption.......We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption....

Selective Two-Photon Absorptive Resonance Femtosecond-Laser Electronic-Excitation Tagging (STARFLEET) Velocimetry in Flow and Combustion Diagnostics

Science.gov (United States)

Jiang, Naibo; Halls, Benjamin R.; Stauffer, Hans U.; Roy, Sukesh; Danehy, Paul M.; Gord, James R.

2016-01-01

Selective Two-Photon Absorptive Resonance Femtosecond-Laser Electronic-Excitation Tagging (STARFLEET), a non-seeded ultrafast-laser-based velocimetry technique, is demonstrated in reactive and non-reactive flows. STARFLEET is pumped via a two-photon resonance in N2 using 202.25-nm 100-fs light. STARFLEET greatly reduces the per-pulse energy required (30 µJ/pulse) to generate the signature FLEET emission compared to the conventional FLEET technique (1.1 mJ/pulse). This reduction in laser energy results in less energy deposited in the flow, which allows for reduced flow perturbations (reactive and non-reactive), increased thermometric accuracy, and less severe damage to materials. Velocity measurements conducted in a free jet of N2 and in a premixed flame show good agreement with theoretical velocities and further demonstrate the significantly less-intrusive nature of STARFLEET.

Photon absorption mechanism in the 4He(γ, npp)n reaction

International Nuclear Information System (INIS)

Emura, T.; Endo, I.; Endo, S.

1990-09-01

We measured the 4 He(γ, npp)n reaction in a kinematically complete way for the first time using the large-acceptance TAGX spectrometer and tagged photons at E γ = 135-455 MeV. The momentum and angular distributions of the nucleons are explained by assuming that photons are absorbed either on the two-nucleon systems (np and pp) or on the three nucleon system (npp). The data can not be reproduced well by the photon absorption on the np system only. (author)

The role of molecular conformation and polarizable embedding for one- and two-photon absorption of disperse orange 3 in solution.

Science.gov (United States)

Silva, Daniel L; Murugan, N Arul; Kongsted, Jacob; Rinkevicius, Zilvinas; Canuto, Sylvio; Ågren, Hans

2012-07-19

Solvent effects on the one- and two-photon absorption (1PA and 2PA) of disperse orange 3 (DO3) in dimethyl sulfoxide (DMSO) are studied using a discrete polarizable embedding (PE) response theory. The scheme comprises a quantum region containing the chromophore and an atomically granulated classical region for the solvent accounting for full interactions within and between the two regions. Either classical molecular dynamics (MD) or hybrid Car-Parrinello (CP) quantum/classical (QM/MM) molecular dynamics simulations are employed to describe the solvation of DO3 in DMSO, allowing for an analysis of the effect of the intermolecular short-range repulsion, long-range attraction, and electrostatic interactions on the conformational changes of the chromophore and also the effect of the solute-solvent polarization. PE linear response calculations are performed to verify the character, solvatochromic shift, and overlap of the two lowest energy transitions responsible for the linear absorption spectrum of DO3 in DMSO in the visible spectral region. Results of the PE linear and quadratic response calculations, performed using uncorrelated solute-solvent configurations sampled from either the classical or hybrid CP QM/MM MD simulations, are used to estimate the width of the line shape function of the two electronic lowest energy excited states, which allow a prediction of the 2PA cross-sections without the use of empirical parameters. Appropriate exchange-correlation functionals have been employed in order to describe the charge-transfer process following the electronic transitions of the chromophore in solution.

Two Photon Absorption Laser Induced Fluorescence for Neutral Hydrogen Profile Measurements

Energy Technology Data Exchange (ETDEWEB)

Scime, Earl E. [West Virginia Univ., Morgantown, WV (United States)

2016-09-23

The magnitude and spatial dependence of neutral density in magnetic confinement fusion experiments is a key physical parameter, particularly in the plasma edge. Modeling codes require precise measurements of the neutral density to calculate charge-exchange power losses and drag forces on rotating plasmas. However, direct measurements of the neutral density are problematic. In this work, we proposed to construct a laser-based diagnostic capable of providing spatially resolved measurements of the neutral density in the edge of plasma in the DIII-D tokamak. The diagnostic concept is based on two-photon absorption laser induced fluorescence (TALIF). By injecting two beams of 205 nm light (co or counter propagating), ground state hydrogen (or deuterium or tritium) can be excited from the n = 1 level to the n = 3 level at the location where the two beams intersect. Individually, the beams experience no absorption, and therefore have no difficulty penetrating even dense plasmas. After excitation, a fraction of the hydrogen atoms decay from the n = 3 level to the n = 2 level and emit photons at 656 nm (the H_α line). Calculations based on the results of previous TALIF experiments in magnetic fusion devices indicated that a laser pulse energy of approximately 3 mJ delivered in 5 ns would provide sufficient signal-to-noise for detection of the fluorescence. In collaboration with the DIII-D engineering staff and experts in plasma edge diagnostics for DIII-D from Oak Ridge National Laboratory (ORNL), WVU researchers designed a TALIF system capable of providing spatially resolved measurements of neutral deuterium densities in the DIII-D edge plasma. The laser systems were specified, purchased, and assembled at WVU. The TALIF system was tested on a low-power hydrogen discharge at WVU and the plan was to move the instrument to DIII-D for installation in collaboration with ORNL researchers. After budget cuts at DIII-D, the DIII-D facility declined to support

Two Photon Absorption Laser Induced Fluorescence for Neutral Hydrogen Profile Measurements

International Nuclear Information System (INIS)

Scime, Earl E.

2016-01-01

The magnitude and spatial dependence of neutral density in magnetic confinement fusion experiments is a key physical parameter, particularly in the plasma edge. Modeling codes require precise measurements of the neutral density to calculate charge-exchange power losses and drag forces on rotating plasmas. However, direct measurements of the neutral density are problematic. In this work, we proposed to construct a laser-based diagnostic capable of providing spatially resolved measurements of the neutral density in the edge of plasma in the DIII-D tokamak. The diagnostic concept is based on two-photon absorption laser induced fluorescence (TALIF). By injecting two beams of 205 nm light (co or counter propagating), ground state hydrogen (or deuterium or tritium) can be excited from the n = 1 level to the n = 3 level at the location where the two beams intersect. Individually, the beams experience no absorption, and therefore have no difficulty penetrating even dense plasmas. After excitation, a fraction of the hydrogen atoms decay from the n = 3 level to the n = 2 level and emit photons at 656 nm (the H α line). Calculations based on the results of previous TALIF experiments in magnetic fusion devices indicated that a laser pulse energy of approximately 3 mJ delivered in 5 ns would provide sufficient signal-to-noise for detection of the fluorescence. In collaboration with the DIII-D engineering staff and experts in plasma edge diagnostics for DIII-D from Oak Ridge National Laboratory (ORNL), WVU researchers designed a TALIF system capable of providing spatially resolved measurements of neutral deuterium densities in the DIII-D edge plasma. The laser systems were specified, purchased, and assembled at WVU. The TALIF system was tested on a low-power hydrogen discharge at WVU and the plan was to move the instrument to DIII-D for installation in collaboration with ORNL researchers. After budget cuts at DIII-D, the DIII-D facility declined to support installation on their

Two-Photon Activation of p-Hydroxyphenacyl Phototriggers: Toward Spatially Controlled Release of Diethyl Phosphate and ATP.

Science.gov (United States)

Houk, Amanda L; Givens, Richard S; Elles, Christopher G

2016-03-31

Two-photon activation of the p-hydroxyphenacyl (pHP) photoactivated protecting group is demonstrated for the first time using visible light at 550 nm from a pulsed laser. Broadband two-photon absorption measurements reveal a strong two-photon transition (>10 GM) near 4.5 eV that closely resembles the lowest-energy band at the same total excitation energy in the one-photon absorption spectrum of the pHP chromophore. The polarization dependence of the two-photon absorption band is consistent with excitation to the same S3 ((1)ππ*) excited state for both one- and two-photon activation. Monitoring the progress of the uncaging reaction under nonresonant excitation at 550 nm confirms a quadratic intensity dependence and that two-photon activation of the uncaging reaction is possible using visible light in the range 500-620 nm. Deprotonation of the pHP chromophore under mildly basic conditions shifts the absorption band to lower energy (3.8 eV) in both the one- and two-photon absorption spectra, suggesting that two-photon activation of the pHP chromophore may be possible using light in the range 550-720 nm. The results of these measurements open the possibility of spatially and temporally selective release of biologically active compounds from the pHP protecting group using visible light from a pulsed laser.

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.

Science.gov (United States)

Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

2010-09-01

Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

Science.gov (United States)

Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.

2010-01-01

The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies. PMID:20693997

Two-photon or higher-order absorbing optical materials and methods of use

Science.gov (United States)

Marder, Seth (Inventor); Perry, Joseph (Inventor)

2012-01-01

Compositions capable of simultaneous two-photon absorption and higher order absorptivities are provided. Compounds having a donor-pi-donor or acceptor-pi-acceptor structure are of particular interest, where the donor is an electron donating group, acceptor is an electron accepting group, and pi is a pi bridge linking the donor and/or acceptor groups. The pi bridge may additionally be substituted with electron donating or withdrawing groups to alter the absorptive wavelength of the structure. Also disclosed are methods of generating an excited state of such compounds through optical stimulation with light using simultaneous absorption of photons of energies individually insufficient to achieve an excited state of the compound, but capable of doing so upon simultaneous absorption of two or more such photons. Applications employing such methods are also provided, including controlled polymerization achieved through focusing of the light source(s) used.

Thermally activated delayed fluorescence organic dots for two-photon fluorescence lifetime imaging

Science.gov (United States)

He, Tingchao; Ren, Can; Li, Zhuohua; Xiao, Shuyu; Li, Junzi; Lin, Xiaodong; Ye, Chuanxiang; Zhang, Junmin; Guo, Lihong; Hu, Wenbo; Chen, Rui

2018-05-01

Autofluorescence is a major challenge in complex tissue imaging when molecules present in the biological tissue compete with the fluorophore. This issue may be resolved by designing organic molecules with long fluorescence lifetimes. The present work reports the two-photon absorption (TPA) properties of a thermally activated delayed fluorescence (TADF) molecule with carbazole as the electron donor and dicyanobenzene as the electron acceptor (i.e., 4CzIPN). The results indicate that 4CzIPN exhibits a moderate TPA cross-section (˜9 × 10-50 cm4 s photon-1), high fluorescence quantum yield, and a long fluorescence lifetime (˜1.47 μs). 4CzIPN was compactly encapsulated into an amphiphilic copolymer via nanoprecipitation to achieve water-soluble organic dots. Interestingly, 4CzIPN organic dots have been utilized in applications involving two-photon fluorescence lifetime imaging (FLIM). Our work aptly demonstrates that TADF molecules are promising candidates of nonlinear optical probes for developing next-generation multiphoton FLIM applications.

Models for Photon-photon Total Cross-sections

OpenAIRE

Godbole, RM; Grau, A; Pancheri, G

1999-01-01

We present here a brief overview of recent models describing the photon-photon cross-section into hadrons. We shall show in detail results from the eikonal minijet model, with and without soft gluon summation.

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.

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

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.

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.)

Photon statistical properties of photon-added two-mode squeezed coherent states

International Nuclear Information System (INIS)

Xu Xue-Fen; Wang Shuai; Tang Bin

2014-01-01

We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states (PA-TMSCS). We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS. Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PA-TMSCS. Compared with that of the TMSCS, the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode; further, that the photon addition essentially shifts the photon number distribution. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Coherent single-photon absorption by single emitters coupled to one-dimensional nanophotonic waveguides

Energy Technology Data Exchange (ETDEWEB)

Chen Yuntian; Wubs, Martijn; Moerk, Jesper [DTU Fotonik, Department of Photonics Engineering, Oersteds Plads, DK-2800 Kgs Lyngby (Denmark); Koenderink, A Femius, E-mail: yche@fotonik.dtu.dk [Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, 1098 XG Amsterdam (Netherlands)

2011-10-15

We study the dynamics of single-photon absorption by a single emitter coupled to a one-dimensional waveguide that simultaneously provides channels for spontaneous emission (SE) decay and a channel for the input photon. We have developed a time-dependent theory that allows us to specify any input single-photon wavepacket guided by the waveguide as the initial condition, and calculate the excitation probability of the emitter, as well as the time evolution of the transmitted and reflected fields. For single-photon wavepackets with a Gaussian spectrum and temporal shape, we obtain analytical solutions for the dynamics of absorption, with maximum atomic excitation {approx}40%. We furthermore propose a terminated waveguide to aid the single-photon absorption. We found that for an emitter placed at an optimal distance from the termination, the maximum atomic excitation due to an incident single-photon wavepacket can exceed 70%. This high value is a direct consequence of the high SE {beta}-factor for emission into the waveguide. Finally, we have also explored whether waveguide dispersion could aid single-photon absorption by pulse shaping. For a Gaussian input wavepacket, we found that the absorption efficiency can be improved by a further 4% by engineering the dispersion. Efficient single-photon absorption by a single emitter has potential applications in quantum communication and quantum computation. (paper)

Induced absorption and stimulated emission in a driven two-level atom

International Nuclear Information System (INIS)

Mavroyannis, C.

1992-01-01

We have considered the induced processes that occur in a driven two-level atom, where a laser photon is absorbed and emitted by the ground and by the excited states of the atom, respectively. In the low-intensity limit of the laser field, the induced spectra arising when a laser photon is absorbed by the ground state of the atom consist of two peaks describing induced absorption and stimulated-emission processes, respectively, where the former prevails over the latter. Asymmetry of the spectral lines occurs at off-resonance and its extent depends on the detuning of the laser field. The physical. process where a laser photon is emitted by the excited state is the reverse of that arising from the absorption of a laser photon by the ground state of the atom. The former differs from the latter in that the emission of a laser photon by the excited state occurs in the low frequency regime and that the stimulated-emission process prevails over that of the induced absorption. In this case, amplification of ultrashort pulses is likely to occur without the need of population inversion between the optical transitions. The computed spectra are graphically presented and discussed. (author)

Two-Photon Fluorescence Microscopy Developed for Microgravity Fluid Physics

Science.gov (United States)

Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

2004-01-01

Recent research efforts within the Microgravity Fluid Physics Branch of the NASA Glenn Research Center have necessitated the development of a microscope capable of high-resolution, three-dimensional imaging of intracellular structure and tissue morphology. Standard optical microscopy works well for thin samples, but it does not allow the imaging of thick samples because of severe degradation caused by out-of-focus object structure. Confocal microscopy, which is a laser-based scanning microscopy, provides improved three-dimensional imaging and true optical sectioning by excluding the out-of-focus light. However, in confocal microscopy, out-of-focus object structure is still illuminated by the incoming beam, which can lead to substantial photo-bleaching. In addition, confocal microscopy is plagued by limited penetration depth, signal loss due to the presence of a confocal pinhole, and the possibility of live-cell damage. Two-photon microscopy is a novel form of laser-based scanning microscopy that allows three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon microscopy, it utilizes the nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption because of the nonlinear (i.e., quadratic) electric field dependence, so an ultrafast pulsed laser source must typically be employed. On the other hand, this stringent energy density requirement effectively localizes fluorophore excitation to the focal volume. Consequently, two-photon microscopy provides optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction in photo-damage because of the longer excitation wavelength, a reduction in background fluorescence, and a 4 increase in penetration depth over confocal methods because of the reduction in Rayleigh scattering.

Doppler-free two-photon excitation of 238U

International Nuclear Information System (INIS)

Hodgkinson, D.P.; Wort, D.J.H.

1981-04-01

A theory of resonantly enhanced two-photon absorption is presented and tested in a number of experiments in which 238 U vapour is excited by two continuous wave dye lasers. Good quantitative agreement between theory and experiment is found. In particular the central prediction of the theory, that antiparallel laser beams of modest intensity can pump an appreciable fraction of the Maxwell velocity distribution, has been checked directly by measuring the spectral width of the fluorescence from the two-photon excited level. (author)

Distribution of photon absorption rates across the rat retina.

Science.gov (United States)

Williams, T P; Webbers, J P; Giordano, L; Henderson, R P

1998-04-15

1. An investigation into the distribution of light intensity across the rat retina was carried out on excised, intact rat eyes exposed to Ganzfeld illumination from a helium-neon laser (543 nm). 2. Some of the light entering the eyes exits through the sclera where its intensity can be monitored with an optical 'pick-up' that samples the intensity coming from a small region of external sclera and underlying retina. The spatial resolution of the pick-up is such that it samples light that has passed through ca 2 % of the rods in the rat eye. 3. Some of the laser light is absorbed by the rod pigment, rhodopsin, which gradually bleaches. Bleaching in the retina, in turn, causes an exponential increase in intensity emanating from the sclera. By monitoring this intensity increase, we are able to measure two important parameters in a single bleaching run: the local rhodopsin concentration and the local intensity falling on the rods. 4. With an ocular transmission photometer, we have measured both the local intensity and the local rhodopsin concentration across wide regions of rat retina. Both pigmented and albino rats were studied. 5. The distributions of rhodopsin and intensity were both nearly uniform; consequently, the product, (rhodopsin concentration) x (intensity), was similarly nearly equal across the retina. This means that the initial rate of photon absorption is about the same at all retinal locations. 6. Interpreted in terms of photostasis (the regulation of daily photon catch), this means that the rate of photon absorption is about the same in each rod, viz. 14 400 photons absorbed per rod per second. Since this rate of absorption is sufficient to saturate the rod, one possible purpose of photostasis is to maintain the rod system in a saturated state during daylight hours.

Engineering Photon-Photon Interactions within Rubidium-Filled Waveguides

Science.gov (United States)

Perrella, C.; Light, P. S.; Vahid, S. Afshar; Benabid, F.; Luiten, A. N.

2018-04-01

Strong photon-photon interactions are a required ingredient for deterministic two-photon optical quantum logic gates. Multiphoton transitions in dense atomic vapors have been shown to be a promising avenue for producing such interactions. The strength of a multiphoton interaction can be enhanced by conducting the interaction in highly confined geometries such as small-cross-section optical waveguides. We demonstrate, both experimentally and theoretically, that the strength of such interactions scale only with the optical mode diameter, d , not d2 as might be initially expected. This weakening of the interaction arises from atomic motion inside the waveguides. We create an interaction between two optical signals, at 780 and 776 nm, using the 5 S1 /2→5 D5 /2 two-photon transition in rubidium vapor within a range of hollow-core fibers with different core sizes. The interaction strength is characterized by observing the absorption and phase shift induced on the 780-nm beam, which is in close agreement with theoretical modeling that accounts for the atomic motion inside the fibers. These observations demonstrate that transit-time effects upon multiphoton transitions are of key importance when engineering photon-photon interactions within small-cross-section waveguides that might otherwise be thought to lead to enhanced optical nonlinearity through increased intensities.

Absorption imaging of a quasi-two-dimensional gas: a multiple scattering analysis

International Nuclear Information System (INIS)

Chomaz, L; Corman, L; Yefsah, T; Desbuquois, R; Dalibard, J

2012-01-01

Absorption imaging with quasi-resonant laser light is a commonly used technique for probing ultra-cold atomic gases in various geometries. In this paper, we investigate some non-trivial aspects of this method when applying the method to in situ diagnosis of a quasi-two-dimensional (2D) gas. Using Monte Carlo simulations we study the modification of the absorption cross-section of a photon when it undergoes multiple scattering in the gas. We determine the variations of the optical density with various parameters, such as the detuning of the light from the atomic resonance and the thickness of the gas. We compare our results to the known 3D result (the Beer-Lambert law) and outline the specific features of the 2D case. (paper)

Measure of total nuclear absorption cross sections of photons in the Δ (1232) range. Studied nucleus 12C and 208Pb

International Nuclear Information System (INIS)

Ghedira, Lotfi

1984-01-01

We present a new determination of the nuclear total photoabsorption cross section, on carbon and lead in the Δ 33 resonance region: 133 MeV ≤ E γ ≤ 531 MeV. The principle of the experimental method is the measurement of the hadronic products emitted during the absorption process. We used the Saclay tagged photon beam obtained by flight annihilation of positrons. The reaction target was placed inside a cylindrical Nal scintillator, covering 93 pc of 4π. A set of plastic scintillators covered the inside of the detector in order to determine the charge multiplicity of the hadronic events. The very large efficiency of this detector allowed the detection of 70 to 80 pc of the total number of hadronic events, so that the uncertainties induced by the extrapolation of the undetected part of the cross section are small. The total hadronic cross section was found to be close to 400 μb/ nucleon at the maximum for both C and Pb. In addition to the total cross section we give values for a few partial cross sections. Previous experimental work as well as theoretical predictions are compared to our results. (author) [fr

Thrust distribution of two-jet like events at a photon-photon collider

International Nuclear Information System (INIS)

Kanakubo, Fumiko

1995-01-01

One of the advantages of using a photon-photon collision with the same helicity is that the continuum qq-bar production is suppressed at the lowest order (α s 0 ). However, the helicity suppression does not take place for the gluon radiation process, and qq-barg can be two-jet like. We evaluate the cross sections of the two-jet like events in a photon-photon collision, and present the thrust distributions. We take into account the QCD effect to all orders in α s in the leading-double-log approximation, and show the suppression due to this effect. The evaluation with the energy and the polarization distributions of the photon suggests that the contaminating photons with the opposite helicity contribute dominantly to the two-jet like process. (author)

Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

Science.gov (United States)

Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

2013-08-26

We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

Two-photon transitions to exciton polaritons

International Nuclear Information System (INIS)

Hassan, A.R.

1979-08-01

A semiclassical theory for the creation of excitonic polariton states by two-photon absorption, via an intermediate exciton state, is given. A band model has been introduced which gives the dominant contribution to this process. A numerical calculation is found to be in good agreement with a recent observation in CuCl. (author)

Theory of two-photon interactions with broadband down-converted light and entangled photons

International Nuclear Information System (INIS)

Dayan, Barak

2007-01-01

When two-photon interactions are induced by down-converted light with a bandwidth that exceeds the pump bandwidth, they can obtain a behavior that is pulselike temporally, yet spectrally narrow. At low photon fluxes this behavior reflects the time and energy entanglement between the down-converted photons. However, two-photon interactions such as two-photon absorption (TPA) and sum-frequency generation (SFG) can exhibit such a behavior even at high power levels, as long as the final state (i.e., the atomic level in TPA, or the generated light in SFG) is narrow-band enough. This behavior does not depend on the squeezing properties of the light, is insensitive to linear losses, and has potential applications. In this paper we describe analytically this behavior for traveling-wave down conversion with continuous or pulsed pumping, both for high- and low-power regimes. For this we derive a quantum-mechanical expression for the down-converted amplitude generated by an arbitrary pump, and formulate operators that represent various two-photon interactions induced by broadband light. This model is in excellent agreement with experimental results of TPA and SFG with high-power down-converted light and with entangled photons [Dayan et al., Phys. Rev. Lett. 93, 023005 (2004); 94, 043602 (2005); Pe'er et al., ibid. 94, 073601 (2005)

Chemical control of channel interference in two-photon absorption processes.

Science.gov (United States)

Alam, Md Mehboob; Chattopadhyaya, Mausumi; Chakrabarti, Swapan; Ruud, Kenneth

2014-05-20

The two-photon absorption (TPA) process is the simplest and hence the most studied nonlinear optical phenomenon, and various aspects of this process have been explored in the past few decades, experimentally as well as theoretically. Previous investigations have shown that the two-photon (TP) activity of a molecular system can be tuned, and at present, performance-tailored TP active materials are easy to develop by monitoring factors such as length of conjugation, dimensionality of charge-transfer network, strength of donor-acceptor groups, polarity of solvents, self-aggregation, H-bonding, and micellar encapsulation to mention but a few. One of the most intriguing phenomena affecting the TP activity of a molecule is channel interference. The phrase "channel interference" implies that if the TP transition from one electronic state to another involves more than one optical pathway or channel, characterized by the corresponding transition dipole moment (TDM) vectors, the channels may interfere with each other depending upon the angles between the TDM vectors and hence can either increase (constructive interference) or decrease (destructive interference) the overall TP activity of a system to a significant extent. This phenomenon was first pointed out by Cronstrand, Luo, and Ågren [Chem. Phys. Lett. 2002, 352, 262-269] in two-dimensional systems (i.e., only involving two components of the transition moment vectors). For three-dimensional molecules, an extended version of this idea was required. In order to fill this gap, we developed a generalized model for describing and exploring channel interference, valid for systems of any dimensionality. We have in particular applied it to through-bond (TB) and through-space (TS) charge-transfer systems both in gas phase and in solvents with different polarities. In this Account, we will, in addition to briefly describing the concept of channel interference, discuss two key findings of our recent work: (1) how to control the

Two photon absorption energy transfer in the light-harvesting complex of photosystem II (LHC-II) modified with organic boron dye

Science.gov (United States)

Chen, Li; Liu, Cheng; Hu, Rui; Feng, Jiao; Wang, Shuangqing; Li, Shayu; Yang, Chunhong; Yang, Guoqiang

2014-07-01

The plant light-harvesting complexes of photosystem II (LHC-II) play important roles in collecting solar energy and transferring the energy to the reaction centers of photosystems I and II. A two photon absorption compound, 4-(bromomethyl)-N-(4-(dimesitylboryl)phenyl)-N-phenylaniline (DMDP-CH2Br), was synthesized and covalently linked to the LHC-II in formation of a LHC-II-dye complex, which still maintained the biological activity of LHC-II system. Under irradiation with femtosecond laser pulses at 754 nm, the LHC-II-dye complex can absorb two photons of the laser light effectively compared with the wild type LHC-II. The absorbed excitation energy is then transferred to chlorophyll a with an obvious fluorescence enhancement. The results may be interesting and give potentials for developing hybrid photosystems.

Dynamical Evolution of Properties for Atom and Field in the Process of Two-Photon Absorption and Emission Between Atomic Levels

Science.gov (United States)

Wang, Jian-ming; Xu, Xue-xiang

2018-04-01

Using dressed state method, we cleverly solve the dynamics of atom-field interaction in the process of two-photon absorption and emission between atomic levels. Here we suppose that the atom is initially in the ground state and the optical field is initially in Fock state, coherent state or thermal state, respectively. The properties of the atom, including the population in excited state and ground state, the atom inversion, and the properties for optical field, including the photon number distribution, the mean photon number, the second-order correlation function and the Wigner function, are discussed in detail. We derive their analytical expressions and then make numerical analysis for them. In contrast with Jaynes-Cummings model, some similar results, such as quantum Rabi oscillation, revival and collapse, are also exhibit in our considered model. Besides, some novel nonclassical states are generated.

Evaluation of mitochondrial activity by two-photon absorption with near-field multioptical fiber probes

Science.gov (United States)

Kanazashi, Yasuaki; Takara, Naoshi; Iwami, Kentaro; Ohta, Yoshihiro; Umeda, Norihiro

2018-04-01

pH measurements enable the direct monitoring and evaluation of mitochondrial activity. We constructed a scanning near-field optical microscopy system with multioptical fiber probes using the two-photon absorption of a pH-sensitive fluorescent dye, SNARF-4F, to measure the activity difference of mitochondrial aggregates. pH can be monitored through the fluorescence intensity ratio (FIR) of SNARF-4F. We derived a calibration curve of the FIR as a function of pH. The FIR dynamic responses were measured by adding hydrochloric acid to the buffer solution. Using the developed system, we simultaneously measured the pH changes at two different locations in the SNARF-4F solution. Mitochondrial samples were prepared using optical tweezers to control the number and position of mitochondria. Mitochondrial pH changes (ΔpH) between 0.05 and 0.57 were observed after adding a nutritional supplement (malate and glutamate). In addition, in the comparative experiment on the activities of two mitochondrial populations, the obtained result suggested that the activity differs depending on the difference in the number of mitochondria.

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.

Measurement of electron beam polarization from unstrained GaAs via two-photon photoemission

Energy Technology Data Exchange (ETDEWEB)

McCarter, J.L., E-mail: jlm2ar@virginia.edu [Department of Physics, University of Virginia, Charlottesville, VA 22901 (United States); Afanasev, A. [Department of Physics, The George Washington University, Washington, DC 20052 (United States); Gay, T.J. [Jorgensen Hall, University of Nebraska, Lincoln, NE 68588 (United States); Hansknecht, J. [Thomas Jefferson National Accelerator Facility, 12050 Jefferson Avenue, Suite 500, Newport News, VA 23606 (United States); Kechiantz, A. [Department of Physics, The George Washington University, Washington, DC 20052 (United States); Poelker, M. [Thomas Jefferson National Accelerator Facility, 12050 Jefferson Avenue, Suite 500, Newport News, VA 23606 (United States)

2014-02-21

Two-photon absorption of 1560 nm light was used to generate polarized electron beams from unstrained GaAs photocathodes of varying thickness: 625 μm, 0.32 μm, and 0.18 μm. For each photocathode, the degree of spin polarization of the photoemitted beam was less than 50%, contradicting earlier predictions based on simple quantum mechanical selection rules for spherically-symmetric systems but consistent with the more sophisticated model of Bhat et al. (Phys. Rev. B 71 (2005) 035209). Polarization via two-photon absorption was the highest from the thinnest photocathode sample and comparable to that obtained via one-photon absorption (using 778 nm light), with values 40.3±1.0% and 42.6±1.0%, respectively.

Performance Analysis of Spectral-Phase-Encoded Optical CDMA System Using Two-Photon-Absorption Receiver Structure for Asynchronous and Slot-Level Synchronous Transmitters

Science.gov (United States)

Jamshidi, Kambiz; Salehi, Jawad A.

2007-06-01

In this paper, we analyze the performance of a nonlinear two-photon-absorption (TPA) receiver and compare its performance with that of a single-photon-absorption (SPA) receiver in the context of spectral-phase-encoded optical code-division multiple access (CDMA) technique. The performances for the above systems are evaluated for two different transmission scenarios, namely, asynchronous and slot-level synchronous transmitters. Performance evaluation includes different sources of degradation such as multiple-access interference, noise due to optical amplification, shot noise, and thermal noise. In obtaining the performance, the mean and variance of the received signal in each of the above techniques are derived, and bit error rate is obtained using Gaussian approximation. In general, it is shown that TPA receivers are superior in performance with respect to SPA receivers when the receiver employs a much slower photodetector in comparison with the laser's transmitted pulse duration. This, indeed, is the reason behind the choice of nonlinear receivers, such as TPA, in most spectral-phase-encoded optical CDMA systems.

Monte Carlo simulation of two-photon processes

International Nuclear Information System (INIS)

Daverveldt, P.H.W.M.

1985-01-01

During the last two decades e + e - collider experiments provided physicists with a wealth of important discoveries concerning elementary particle physics. This thesis explains in detail how the Monte Carlo approach can be applied to establish the comparison between two-photon experiments and theory. The author describes the main motives for and objectives of two-photon research. He defines the kinematics and pays attention to some special kinematical regions. Also a popular approximation for the exact differential cross section is reviewed. Next he discusses the calculation of the complete lowest order cross section for processes with four leptons in the final state and for reactions such as e + e - →e + e - qanti q, e + e - →μ + μ - qanti q. Radiative corrections to the multiperipheral diagrams are considered. The author explains in detail the distinction between soft and hard photon corrections which turns out to be somewhat more tricky than in the case of radiative corrections to one-photon processes. Finally, he presents some results which were obtained by using the event generators. (Auth.)

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.

Silole-Based Red Fluorescent Organic Dots for Bright Two-Photon Fluorescence In vitro Cell and In vivo Blood Vessel Imaging.

Science.gov (United States)

Chen, Bin; Feng, Guangxue; He, Bairong; Goh, Chiching; Xu, Shidang; Ramos-Ortiz, Gabriel; Aparicio-Ixta, Laura; Zhou, Jian; Ng, Laiguan; Zhao, Zujin; Liu, Bin; Tang, Ben Zhong

2016-02-10

Robust luminescent dyes with efficient two-photon fluorescence are highly desirable for biological imaging applications, but those suitable for organic dots fabrication are still rare because of aggregation-caused quenching. In this work, a red fluorescent silole, 2,5-bis[5-(dimesitylboranyl)thiophen-2-yl]-1-methyl-1,3,4-triphenylsilole ((MesB)2 DTTPS), is synthesized and characterized. (MesB)2 DTTPS exhibits enhanced fluorescence efficiency in nanoaggregates, indicative of aggregation-enhanced emission (AEE). The organic dots fabricated by encapsulating (MesB)2 DTTPS within lipid-PEG show red fluorescence peaking at 598 nm and a high fluorescence quantum yield of 32%. Upon excitation at 820 nm, the dots show a large two-photon absorption cross section of 3.43 × 10(5) GM, which yields a two-photon action cross section of 1.09 × 10(5) GM. These (MesB)2 DTTPS dots show good biocompatibility and are successfully applied to one-photon and two-photon fluorescence imaging of MCF-7 cells and two-photon in vivo visualization of the blood vascular of mouse muscle in a high-contrast and noninvasive manner. Moreover, the 3D blood vasculature located at the mouse ear skin with a depth of over 100 μm can also be visualized clearly, providing the spatiotemporal information about the whole blood vascular network. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coherent photon scattering cross sections for helium near the delta resonance

International Nuclear Information System (INIS)

Delli Carpini, D.; Booth, E.C.; Miller, J.P.; Igarashi, R.; Bergstrom, J.; Caplan, H.; Doss, M.; Hallin, E.; Rangacharyulu, C.; Skopik, D.; Lucas, M.A.; Nathan, A.M.; Wells, D.P.

1991-01-01

The angular distributions for coherent photon scattering from 4 He were measured at average laboratory bremsstrahlung energies of 187, 235, and 280 MeV. The experiment was performed at the Saskatchewan Accelerator Laboratory using the new high duty factor electron beam. The scattered photons were observed with a high-resolution NaI(Tl) total absorption scintillation detector. These measurements are intended to investigate modification of the Δ properties inside the nuclear medium and the treatment of nonresonant contributions to the scattering cross sections. The results are compared to theoretical calculations in the isobar-hole model. Clear deviations from the theory are evident at all energies, especially at 187 MeV

Effective photons in weakly absorptive dielectric media and the Beer–Lambert–Bouguer law

International Nuclear Information System (INIS)

Judge, A C; Brownless, J S; Martijn de Sterke, C; Bhat, N A R; Sipe, J E; Steel, M J

2014-01-01

We derive effective photon modes that facilitate an intuitive and convenient picture of photon dynamics in a structured Kramers–Kronig dielectric in the limit of weak absorption. Each mode is associated with a mode field distribution that includes the effects of both material and structural dispersion, and an effective line-width that determines the temporal decay rate of the photon. These results are then applied to obtain an expression for the Beer–Lambert–Bouguer law absorption coefficient for unidirectional propagation in structured media consisting of dispersive, weakly absorptive dielectric materials

Tuning Ag29 nanocluster light emission from red to blue with one and two-photon excitation.

Science.gov (United States)

Russier-Antoine, Isabelle; Bertorelle, Franck; Hamouda, Ramzi; Rayane, Driss; Dugourd, Philippe; Sanader, Željka; Bonačić-Koutecký, Vlasta; Brevet, Pierre-François; Antoine, Rodolphe

2016-02-07

We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ∼2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ∼800 nm for Ag29(DHLA)12 is higher than 10(4) GM and the hyperpolarizability is 106 × 10(-30) esu at the same excitation wavelength. The two-photon excited fluorescence spectrum appears strongly blue-shifted as compared to the one-photon excited spectrum, displaying a broad band between 400 and 700 nm. The density functional theory (DFT) provides insight into the structural and electronic properties of Ag29(DHLA)12 as well as into interplay between metallic subunit or core and ligands which is responsible for unique optical properties.

Radiative corrections to two photon physics

International Nuclear Information System (INIS)

Neervan, W.L. van; Vermaseren, J.A.M.

1983-06-01

The authors develop a method to calculate radiative corrections to two photon reactions of the type e + e - →e + e - X where X is an arbitrary final state. To illustrate this they take the example where X stands for a point-like pseudoscalar. It will be shown that the method is an improvement on the standard way in adding real and virtual photon contributions to the (differential) cross-sections. This makes it possible to compute differential and total cross-sections to a very high precision and with a minimum of computer time which is not possible by using more conventional methods. (Auth.)

Photo-induced changes of silicate glasses optical parameters at multi-photon laser radiation absorption

International Nuclear Information System (INIS)

Efimov, O.M.; Glebov, L.B.; Mekryukov, A.M.

1995-01-01

In this paper the results of investigations of the mechanisms of photo-induced changes of alkali-silicate (crown) and lead-silicate (flint) glasses optical parameters upon the exposure to the intense laser radiation, and the basic regularities of these processes are reported. These investigations were performed in Research Center open-quotes S. I. Vavilov State Optical Instituteclose quotes during last 15 years. The kinetics of stable and unstable CC formation and decay, the effect of widely spread impurity ions on these processes, the characteristics of fundamental and impure luminescence, the kinetics of refractive index change under conditions of multi-photon glass matrix excitation, and other properties are considered. On the basis of analysis of received regularities it was shown that the nonlinear coloration of alkali-silicate glasses (the fundamental absorption edge is nearly 6 eV) takes place only as a result of two-photon absorption. Important efforts were aimed at the detection of three- or more photon matrix ionization of these glasses, but they were failed. However it was established that in the lead silicate glasses the long-wave carriers mobility boundary (> 5.6 eV) is placed considerably higher the fundamental absorption edge (∼ 3.5 eV) of material matrix. This results in that the linear color centers formation in the lead silicate glasses is not observed. The coloration of these glasses arises only from the two- or three-photon matrix ionization, and the excitation occurs through virtual states that are placed in the fundamental absorption region. In the report the available mechanisms of photo-induced changes of glasses optical parameters, and some applied aspects of this problem are discussed

Two-photon absorption laser-induced fluorescence of atomic oxygen in the afterglow of pulsed positive corona discharge

Science.gov (United States)

Ono, Ryo; Takezawa, Kei; Oda, Tetsuji

2009-08-01

Atomic oxygen is measured in the afterglow of pulsed positive corona discharge using time-resolved two-photon absorption laser-induced fluorescence. The discharge occurs in a 14 mm point-to-plane gap in dry air. After the discharge pulse, the atomic oxygen density decreases at a rate of 5×104 s-1. Simultaneously, ozone density increases at almost the same rate, where the ozone density is measured using laser absorption method. This agreement between the increasing rate of atomic oxygen and decreasing rate of ozone proves that ozone is mainly produced by the well-known three-body reaction, O+O2+M→O3+M. No other process for ozone production such as O2(v)+O2→O3+O is observed. The spatial distribution of atomic oxygen density is in agreement with that of the secondary streamer luminous intensity. This agreement indicates that atomic oxygen is mainly produced in the secondary streamer channels, not in the primary streamer channels.

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)

Two-photon excited whispering-gallery mode ultraviolet laser from an individual ZnO microneedle

Science.gov (United States)

Zhu, G. P.; Xu, C. X.; Zhu, J.; Lv, C. G.; Cui, Y. P.

2009-02-01

Wurtzite structural ZnO microneedles with hexagonal cross section were fabricated by vapor-phase transport method and an individual microneedle was employed as a lasing microcavity. Under excitation of a femtosecond pulse laser with 800 nm wavelength, the ultraviolet (UV) laser emission was obtained, which presented narrow linewidth and high Q value. The UV emission, resonant mechanism, and laser mode characteristics were discussed in detail. The results demonstrated that the UV laser originated from the whispering-gallery mode induced by two-photon absorption assisted by Rabi oscillation.

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.

One Photon Can Simultaneously Excite Two or More Atoms.

Science.gov (United States)

Garziano, Luigi; Macrì, Vincenzo; Stassi, Roberto; Di Stefano, Omar; Nori, Franco; Savasta, Salvatore

2016-07-22

We consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.

Determination of the absolute two-photon ionization cross section of He by an XUV free electron laser

International Nuclear Information System (INIS)

Sato, Takahiro; Iwasaki, Atsushi; Ishibashi, Kazuki; Okino, Tomoya; Yamanouchi, Kaoru; Adachi, Junichi; Yagishita, Akira; Yazawa, Hiroki; Aoyma, Makoto; Yabashi, Makina; Nagasono, Mitsuru; Higashiya, Atsushi; Ishikawa, Tetsuya; Kannari, Fumihiko; Yamakawa, Koichi; Midorikawa, Katsumi; Nakano, Hidetoshi

2011-01-01

The resonant and non-resonant two-photon single ionization processes of He were investigated using intense free electron laser light in the extreme ultraviolet (XUV) region (53.4-61.4 nm) covering the 1s-2p and 1s-3p resonant transitions of He. On the basis of the dependences of the yield of He + on the XUV light-field intensity at 53.4, 58.4, 56.0 and 61.4 nm, the absolute values of the two-photon ionization cross sections of He at the four different wavelengths and their dependence on the light-field intensity were determined for the first time. (fast track communication)

Two-photon processes in highly charged ions

International Nuclear Information System (INIS)

Jahrsetz, Thorsten

2015-01-01

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.

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.

Poster - 18: New features in EGSnrc for photon cross sections

Energy Technology Data Exchange (ETDEWEB)

Ali, Elsayed; Mainegra-Hing, Ernesto; Rogers, David W.O. [The Ottawa Hospital Cancer Centre, National Research Council Canada, Carleton University (Canada)

2016-08-15

Purpose: To implement two new features in the EGSnrc Monte Carlo system. The first is an option to account for photonuclear attenuation, which can contribute a few percent to the total cross section at the higher end of the energy range of interest to medical physics. The second is an option to use exact NIST XCOM photon cross sections. Methods: For the first feature, the photonuclear total cross sections are generated from the IAEA evaluated data. In the current, first-order implementation, after a photonuclear event, there is no energy deposition or secondary particle generation. The implementation is validated against deterministic calculations and experimental measurements of transmission signals. For the second feature, before this work, if the user explicitly requested XCOM photon cross sections, EGSnrc still used its own internal incoherent scattering cross sections. These differ by up to 2% from XCOM data between 30 keV and 40 MeV. After this work, exact XCOM incoherent scattering cross sections are an available option. Minor interpolation artifacts in pair and triplet XCOM cross sections are also addressed. The default for photon cross section in EGSnrc is XCOM except for the new incoherent scattering cross sections, which have to be explicitly requested. The photonuclear, incoherent, pair and triplet data from this work are available for elements and compounds for photon energies from 1 keV to 100 GeV. Results: Both features are implemented and validated in EGSnrc.Conclusions: The two features are part of the standard EGSnrc distribution as of version 4.2.3.2.

Antimony orthophosphate glasses with large nonlinear refractive indices, low two-photon absorption coefficients, and ultrafast response

International Nuclear Information System (INIS)

Falcao-Filho, E.L.; Araujo, Cid B. de; Bosco, C.A.C.; Maciel, G.S.; Acioli, L.H.; Nalin, M.; Messaddeq, Y.

2005-01-01

Antimony glasses based on the composition Sb 2 O 3 -SbPO 4 were prepared and characterized. The samples present high refractive index, good transmission from 380 to 2000 nm, and high thermal stability. The nonlinear refractive index, n 2 , of the samples was studied using the optical Kerr shutter technique at 800 nm. The third-order correlation signals between pump and probe pulses indicate ultrafast response ( 2 was observed by adding lead oxide to the Sb 2 O 3 -SbPO 4 composition. Large values of n 2 ≅10 -14 cm 2 /W and negligible two-photon absorption coefficients (smaller than 0.01 cm/GW) were determined for all samples. The glass compositions studied present appropriate figure-of-merit for all-optical switching applications

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.

Time-resolved statistics of photon pairs in two-cavity Josephson photonics

Energy Technology Data Exchange (ETDEWEB)

Dambach, Simon; Kubala, Bjoern; Ankerhold, Joachim [Institute for Complex Quantum Systems and IQST, Ulm University (Germany)

2017-06-15

We analyze the creation and emission of pairs of highly nonclassical microwave photons in a setup where a voltage-biased Josephson junction is connected in series to two electromagnetic oscillators. Tuning the external voltage such that the Josephson frequency equals the sum of the two mode frequencies, each tunneling Cooper pair creates one additional photon in both of the two oscillators. The time-resolved statistics of photon emission events from the two oscillators is investigated by means of single- and cross-oscillator variants of the second-order correlation function g{sup (2)}(τ) and the waiting-time distribution w(τ). They provide insight into the strongly correlated quantum dynamics of the two oscillator subsystems and reveal a rich variety of quantum features of light including strong antibunching and the presence of negative values in the Wigner function. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Coherent single-photon absorption by single emitters coupled to one-dimensional nanophotonic waveguides

DEFF Research Database (Denmark)

Chen, Yuntian; Wubs, Martijn; Mørk, Jesper

2011-01-01

-photon wavepacket can exceed 70%. This high value is a direct consequence of the high SE β-factor for emission into the waveguide. Finally, we have also explored whether waveguide dispersion could aid single-photon absorption by pulse shaping. For a Gaussian input wavepacket, we found that the absorption efficiency...

Di-photon cross section measurement and Higgs sensitivity study in the two-photon final state with the ATLAS detector

CERN Document Server

Yuan, Li

2011-01-01

This work is done with the ATLAS collaboration. Three independent methods are proposed to measure the photon trigger efficiency. They are first evaluated using Monte Carlo simulation and then applied on 2010 data. The two photon-based methods show consistent results, with efficiency discrepancy at a few % level. For the method based on electron sample, the statistics is too low to draw conclusion. A detailed QCD di-photon cross-section measurement is performed on a data sample corresponding to a luminosity of 37.2 ±1.2 pb−1, in which a 2D fit method is introduced to extract the signal yields. The differential distributions of the observables Mγγ , pT γγ and Δϕγγ are derived and compared with the predictions from the DIPHOX and RESBOS generators. A good agreement is found for the Mγγ distribution, whereas discrepancies are observed in the pT γγ and Δϕγγ distributions. In the study of the H → γγ channel based on a simulated sample, a deterioration of 4% in the exclusion limit is observed ...

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.

On the theory of the two-photon linear photovoltaic effect in n-GaP

Energy Technology Data Exchange (ETDEWEB)

Rasulov, V. R.; Rasulov, R. Ya., E-mail: r-rasulov51@mail.ru [Fergana State University (Uzbekistan)

2016-02-15

A quantitative theory of the diagonal (ballistic) and nondiagonal (shift) band index contributions to the two-photon current of the linear photovoltaic effect in a semiconductor with a complex band due to the asymmetry of events of electron scattering at phonons and photons is developed. It is shown that processes caused by the simultaneous absorption of two photons do not contribute to the ballistic photocurrent in n-GaP. This is due to the fact that, in this case, there is no asymmetric distribution of the momentum of electrons excited with photons; this distribution arises upon the sequential absorption of two photons with the involvement of LO phonons. It is demonstrated that the temperature dependence of the shift contribution to the two-photon photocurrent in n-GaP is determined by the temperature dependence of the light-absorption coefficient caused by direct optical transitions of electrons between subbands X{sub 1} and X{sub 3}. It is shown that the spectral dependence of the photocurrent has a feature in the light frequency range ω → Δ/2ℏ, which is related to the hump-like shape of subband X{sub 1} in n-GaP{sup 1} and the root-type singularity of the state density determined as k{sub ω}{sup -1}= (2ℏω–Δ){sup –1/2}, where Δ is the energy gap between subbands X{sub 1} and X{sub 3}. The spectral and temperature dependences of the coefficient of absorption of linearly polarized light in n-GaP are obtained with regard to the cone-shaped lower subband of the conduction band.

Perfect absorption in nanotextured thin films via Anderson-localized photon modes

Science.gov (United States)

Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

2015-10-01

The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

Determination of absorption changes from moments of distributions of times of flight of photons: optimization of measurement conditions for a two-layered tissue model.

Science.gov (United States)

Liebert, Adam; Wabnitz, Heidrun; Elster, Clemens

2012-05-01

Time-resolved near-infrared spectroscopy allows for depth-selective determination of absorption changes in the adult human head that facilitates separation between cerebral and extra-cerebral responses to brain activation. The aim of the present work is to analyze which combinations of moments of measured distributions of times of flight (DTOF) of photons and source-detector separations are optimal for the reconstruction of absorption changes in a two-layered tissue model corresponding to extra- and intra-cerebral compartments. To this end we calculated the standard deviations of the derived absorption changes in both layers by considering photon noise and a linear relation between the absorption changes and the DTOF moments. The results show that the standard deviation of the absorption change in the deeper (superficial) layer increases (decreases) with the thickness of the superficial layer. It is confirmed that for the deeper layer the use of higher moments, in particular the variance of the DTOF, leads to an improvement. For example, when measurements at four different source-detector separations between 8 and 35 mm are available and a realistic thickness of the upper layer of 12 mm is assumed, the inclusion of the change in mean time of flight, in addition to the change in attenuation, leads to a reduction of the standard deviation of the absorption change in the deeper tissue layer by a factor of 2.5. A reduction by another 4% can be achieved by additionally including the change in variance.

Integrated three-dimensional photonic nanostructures for achieving near-unity solar absorption and superhydrophobicity

Energy Technology Data Exchange (ETDEWEB)

Kuang, Ping; Lin, Shawn-Yu, E-mail: sylin@rpi.edu [The Future Chips Constellation and the Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Hsieh, Mei-Li [Department of Photonics, National Chia-Tung University, Hsinchu, Taiwan (China)

2015-06-07

In this paper, we proposed and realized 3D photonic nanostructures consisting of ultra-thin graded index antireflective coatings (ARCs) and woodpile photonic crystals. The use of the integrated ARC and photonic crystal structure can achieve broadband, broad-angle near unity solar absorption. The amorphous silicon based photonic nanostructure experimentally shows an average absorption of ∼95% for λ = 400–620 nm over a wide angular acceptance of θ = 0°–60°. Theoretical studies show that a Gallium Arsenide (GaAs) based structure can achieve an average absorption of >95% for λ = 400–870 nm. Furthermore, the use of the slanted SiO{sub 2} nanorod ARC surface layer by glancing angle deposition exhibits Cassie-Baxter state wetting, and superhydrophobic surface is obtained with highest water contact angle θ{sub CB} ∼ 153°. These properties are fundamentally important for achieving maximum solar absorption and surface self-cleaning in thin film solar cell applications.

Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

Directory of Open Access Journals (Sweden)

Héctor L. Otálvaro-Marín

2014-01-01

Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

Investigation of the two-photon decay following the neutron capture in hydrogen

International Nuclear Information System (INIS)

Wuest, N.

1978-01-01

The continuous two-photon radiation, resulting from thermal neutron capture in hydrogen, has been measured. This reaction can be described in second order perturbation theory and occurs besides the dominating 2223.4 keV single-photon radiation. The theoretical ratio between two-photon and one-photon process is 2.8 10 -7 for the case considered here, so coincidence experiments with extremely high sensitivity have to be performed. In order to exclude systematical errors, three measurements with a different experimental set-up have been performed. Besides the total cross section for the two-photon process, the differential cross section has been studied in one of the experiments as a function of the energy ratio of the two photons. For the branching ratio between the two- and one-photon process an upper limit of 2 x 10 -5 could be obtained. So the hypothesis that the neutron capture state and the deuterium ground state one non-orthogonal, is shown to be false. (orig.) [de

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

Total Cross Sections and Event Properties from Real to Virtual Photons

International Nuclear Information System (INIS)

Friberg, Christer; Sjoestrand, Torbjoern

2000-01-01

A model for total cross sections with virtual photons is presented. In particular gamma*-p and gamma*-gamma* cross sections are considered. Our approach extends on a model for photoproduction, where the total cross section is subdivided into three distinct event classes: direct, VMD and anomalous. With increasing photon virtuality, the latter two decrease in importance. Instead Deep Inelastic Scattering dominates, with the direct class being the O(alpha s ) correction thereof. Hence, the model provides a smooth transition between the two regions. By the breakdown into different event classes, one may aim for a complete picture of all event properties. (author)

One, two or three-nucleon photo- absorption in 3He

International Nuclear Information System (INIS)

Tamas, G.

1986-08-01

Pion production and photodisintegration of 3 He are studied in the δ resonance region to try to separate the various photon absorption mechanism by one, two or three nucleons. The results are compared to the existing models

General calculation of the cross section for dark matter annihilations into two photons

Energy Technology Data Exchange (ETDEWEB)

Garcia-Cely, Camilo [Service de Physique Théorique, Université Libre de Bruxelles, Boulevard du Triomphe, CP225, 1050 Brussels (Belgium); Rivera, Andres, E-mail: Camilo.Alfredo.Garcia.Cely@ulb.ac.be, E-mail: afelipe.rivera@udea.edu.co [Instituto de Física, Universidad de Antioquia, Calle 70 No. 52-21, Medellín (Colombia)

2017-03-01

Assuming that the underlying model satisfies some general requirements such as renormalizability and CP conservation, we calculate the non-relativistic one-loop cross section for any self-conjugate dark matter particle annihilating into two photons. We accomplish this by carefully classifying all possible one-loop diagrams and, from them, reading off the dark matter interactions with the particles running in the loop. Our approach is general and leads to the same results found in the literature for popular dark matter candidates such as the neutralinos of the MSSM, minimal dark matter, inert Higgs and Kaluza-Klein dark matter.

General calculation of the cross section for dark matter annihilations into two photons

International Nuclear Information System (INIS)

Garcia-Cely, Camilo; Rivera, Andres

2017-01-01

Assuming that the underlying model satisfies some general requirements such as renormalizability and CP conservation, we calculate the non-relativistic one-loop cross section for any self-conjugate dark matter particle annihilating into two photons. We accomplish this by carefully classifying all possible one-loop diagrams and, from them, reading off the dark matter interactions with the particles running in the loop. Our approach is general and leads to the same results found in the literature for popular dark matter candidates such as the neutralinos of the MSSM, minimal dark matter, inert Higgs and Kaluza-Klein dark matter.

Time evolution of absorption process in nonlinear metallic photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahi R.; Hatef, Ali [Department of Physics and Astronomy, University of Western Ontario, London (Canada)

2009-05-15

The time evolution of the absorption coefficient in metallic photonic crystals has been studied numerically. These crystals are made from metallic spheres which are arranged periodically in air. The refractive index of the metallic spheres depends on the plasma frequency. Probe and pump fields are applied to monitor the absorption process. Ensembles of three-level particles are embedded in the crystal. Nanoparticles are interacting with the metallic crystals via the electron-photon interaction. It is found that when the resonance states lie away from the band edges system goes to transparent state. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Two- and three-photon excitation of Gd3+ in CaAl12O19

International Nuclear Information System (INIS)

Heerdt, M.L.H. ter; Basun, S.A.; Imbusch, G.F.; Yen, W.M.

2002-01-01

We have employed two-photon excitation to study the higher energy levels of Gd 3+ ions in CaAl 12 O 19 and we compare the results with those obtained using conventional UV excitation techniques. Under two-photon excitation, the luminescence intensity exhibits an unusual temporal behavior, a very long build-up followed by a decrease by orders of magnitude, ascribed to a recombination-assisted luminescence excitation mechanism assuming photo-ionization of Gd 3+ ions and trapping of free electrons on deep traps. We also find that the two-photon excitation spectra contain an additional broadening contribution which can be attributed to homogeneous broadening of excitation levels caused by excited state absorption into the conduction band. We believe that this may be a general phenomenon whenever participating photons produce ionization of impurity ions from metastable excited states. The phenomenon can manifest itself also in two-photon ionization spectral hole burning and in up-conversion processes (in the latter case, the homogeneous broadening can be caused by an intra-ion excited-state absorption)

Theoretical studies of one- and two-photon absorption properties for three molecules with different centers (B and N) and peripheral substituted groups [N(CH{sub 3}){sub 2} and CN

Energy Technology Data Exchange (ETDEWEB)

Han Deming [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Feng Jikang, E-mail: jikangf@yahoo.co [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); College of Chemistry, Jilin University, Changchun 130023 (China); Ren Aimin [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Shang Xiaohong [College of Chemistry, Jilin University, Changchun 130023 (China); Liu Xiaojuan [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

2009-08-15

Three molecules with different centers (boron and nitrogen) and peripheral substituted groups [N(CH{sub 3}){sub 2} and CN] have been theoretically studied with B3LYP/6-31G(d) associated with ZINDO and sum-over-states methods. The maximum two-photon absorption cross-section delta{sub max} of the molecule with boron (B) center and N(CH{sub 3}){sub 2} peripheral group is larger than that of the molecule with nitrogen (N) center and N(CH{sub 3}){sub 2} peripheral group. As for the two molecules with N center, the delta{sub max} is obviously increased with the change from N(CH{sub 3}){sub 2} to CN group. This indicates that the large intramolecular charge transfer is in favor of the TPA response.

Pion-pair production by two photons

International Nuclear Information System (INIS)

Terazawa, Hidezumi.

1994-07-01

The cross section for pion-pair production by two photons is calculated approximately by using the low energy theorem previously derived from partially-conserved-axial-vector-current hypothesis and current algebra, and found to agree very well with the experimental data recently obtained by the Mark II, TPC/Two-Gamma and CLEO Collaborations. (author)

Two-Photon Vibrational Spectroscopy using local optical fields of gold and silver nanostructures

Science.gov (United States)

Kneipp, Katrin; Kneipp, Janina; Kneipp, Harald

2007-03-01

Spectroscopic effects can be strongly affected when they take place in the immediate vicinity of metal nanostructures due to coupling to surface plasmons. We introduce a new approach that suggests highly efficient two-photon labels as well as two-photon vibrational spectroscopy for non-destructive chemical probing. The underlying spectroscopic effect is the incoherent inelastic scattering of two photons on the vibrational quantum states performed in the enhanced local optical fields of gold nanoparticles, surface enhanced hyper Raman scattering (SEHRS). We infer effective two-photon cross sections for SEHRS on the order of 10^5 GM, similar or higher than the best known cross sections for two-photon fluorescence. SEHRS combines the advantages of two-photon spectroscopy with the structural information of vibrational spectroscopy, and the high sensitivity and nanometer-scale local confinement of plasmonics-based spectroscopy.

Water-Soluble Triarylborane Chromophores for One- and Two-Photon Excited Fluorescence Imaging of Mitochondria in Cells.

Science.gov (United States)

Griesbeck, Stefanie; Zhang, Zuolun; Gutmann, Marcus; Lühmann, Tessa; Edkins, Robert M; Clermont, Guillaume; Lazar, Adina N; Haehnel, Martin; Edkins, Katharina; Eichhorn, Antonius; Blanchard-Desce, Mireille; Meinel, Lorenz; Marder, Todd B

2016-10-04

Three water-soluble tetracationic quadrupolar chromophores comprising two three-coordinate boron π-acceptor groups bridged by thiophene-containing moieties were synthesised for biological imaging applications. Compound 3 containing the bulkier 5-(3,5-Me2 C6 H2 )-2,2'-(C4 H2 S)2 -5'-(3,5-Me2 C6 H2 ) bridge is stable over a long period of time, exhibits a high fluorescence quantum yield and strong one- and two-photon absorption (TPA), and has a TPA cross section of 268 GM at 800 nm in water. Confocal laser scanning fluorescence microscopy studies in live cells indicated localisation of the chromophore at the mitochondria; moreover, cytotoxicity measurements proved biocompatibility. Thus, chromophore 3 has excellent potential for one- and two-photon-excited fluorescence imaging of mitochondrial function in cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurement of polarization dependence of two-photon absorption coefficient in InP using extended Z-scan technique for thick materials

Science.gov (United States)

Oishi, Masaki; Shinozaki, Tomohisa; Hara, Hikaru; Yamamoto, Kazunuki; Matsusue, Toshio; Bando, Hiroyuki

2018-03-01

The two-photon absorption coefficient β in InP has been measured in the wavelength range of 1640 to 1800 nm by the Z-scan technique in relatively thick materials. The values of β have been evaluated from the fit to the equation including the spatial and temporal profiles of the focused Gaussian beam. The polarization dependence of β has also been measured. The dependence has been expressed very well by the expression of β with the imaginary part of the third-order nonlinear susceptibility tensor χ(3).

Effects of two-photon absorption on all optical logic operation based on quantum-dot semiconductor optical amplifiers

Science.gov (United States)

Zhang, Xiang; Dutta, Niloy K.

2018-01-01

We investigate all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) based Mach-Zehnder interferometer considering the effects of two-photon absorption (TPA). TPA occurs during the propagation of sub-picosecond pulses in QD-SOA, which leads to a change in carrier recovery dynamics in quantum-dots. We utilize a rate equation model to take into account carrier refill through TPA and nonlinear dynamics including carrier heating and spectral hole burning in the QD-SOA. The simulation results show the TPA-induced pumping in the QD-SOA can reduce the pattern effect and increase the output quality of the all-optical logic operation. With TPA, this scheme is suitable for high-speed Boolean logic operation at 320 Gb/s.

Aspects of two-photon physics at linear e+e- colliders

International Nuclear Information System (INIS)

Drees, M.; Godbole, R.M.

1993-01-01

We discuss various reactions at future e + e - and γγ colliders involving real (beamstrahlung or backscattered laser) or quasi-real (bremsstrahlung) photons in the initial state and hadrons in the final state. The production of two central jets with large transverse momentum p T is described in some detail; we give distributions for the rapidity and p T of the jets as well as the di-jet invariant mass, and discuss the relative importance of various initial state configurations and the uncertainties that arise from the at present rather poor knowledge of the parton content of the photon. We also present results for 'mono-jet' production where one jet goes down a beam pipe, for the production of charm, bottom and top quarks, and for single production of W and Z bosons. Where appropriate, the two-photon processes are compared with annihilation reactions leading to similar final states. We also argue that the behaviour of the total inelastic γγ cross section at high energies will probably have little impact on the severity of background problems caused by soft and semi-hard ('minijet') two-photon reactions. We find very large differences in cross sections for all two-photon processes between existing designs for future e + e - colliders, due to the different beamstrahlung spectra; in particular, both designs with >1 events per bunch crossing exist. The number of hardronic two-photon events is expected to rise quickly with the beam energy. Hadronic backgrounds will be even worse if the e + e - collider is converted into a γγ collider. (orig.)

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.

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.

A Successful Attempt to Obtain the Linear Dependence Between One-Photon and Two-Photon Spectral Properties and Hammett Parameters of Various Aromatic Substituents in New π-Extended Asymmetric Organic Chromophores.

Science.gov (United States)

Hu, Nvdan; Gong, Yulong; Wang, Xinchao; Lu, Yao; Peng, Guangyue; Yang, Long; Zhang, Shengtao; Luo, Ziping; Li, Hongru; Gao, Fang

2015-11-01

A series of new asymmetric chromophores containing aromatic substituents and possessing the excellent π-extension in space were prepared through multi-steps routes. One-photon and two-photon spectral properties of these new chromophores could be tuned by these substituents finely and simultaneously. The linear correlation of the wave numbers of the one-photon absorption and emission maxima to Hammett parameters of these substituents was presented. Near infrared two-photon absorption emission integrated areas of the target chromophores were correlated linearly to Hammett constants of these substituted groups.

Two-Photon Pumped Synchronously Mode-Locked Bulk GaAs Laser

Science.gov (United States)

Cao, W. L.; Vaucher, A. M.; Ling, J. D.; Lee, C. H.

1982-04-01

Pulses 7 picoseconds or less in duration have been generated from a bulk GaAs crystal by a synchronous mode-locking technique. The GaAs crystal was optically pumped by two-photon absorption of the emission from a mode-locked Nd:glass laser. Two-photon absorption as the means of excitation increases the volume of the gain medium by increasing the pene-tration depth of the pump intensity, enabling generation of intra-cavity pulses with peak power in the megawatt range. Tuning of the wavelength of the GaAs emission is achieved by varying the temperature. A tuning range covering 840 nm to 885 nm has been observed over a temperature range from 97°K to 260°K. The intensity of the GaAs emission has also been observed to decrease as the temperature of the crystal is increased.

Frequency up-shift in the stimulated thermal scattering under two-photon absorption in liquids and colloids of metal nanoparticles

Science.gov (United States)

Smetanin, I. V.; Erokhin, A. I.; Baranov, A. N.

2018-07-01

We report the results of the experimental and theoretical study of stimulated temperature scattering in toluene and hexane solutions of Ag-nanoparticles, as well as in pure toluene in the two-photon absorption regime. A four-wave mixing scheme with two counter-propagating pump waves of the same frequency is utilised to demonstrate the lasing effect and the amplification of the backscattered anti-Stokes signal. For the first time, we have measured anti-Stokes spectral shifts which turn out to appreciably exceed the Rayleigh line widths in those liquids. It is shown that the amplification effect is provided predominantly by thermally induced coherent polarisation oscillations, while the dynamic interference temperature grating causes the formation of a self-induced optical cavity inside the interaction region.

High-resolution three-dimensional imaging of a depleted CMOS sensor using an edge Transient Current Technique based on the Two Photon Absorption process (TPA-eTCT)

CERN Document Server

García, Marcos Fernández; Echeverría, Richard Jaramillo; Moll, Michael; Santos, Raúl Montero; Moya, David; Pinto, Rogelio Palomo; Vila, Iván

2016-01-01

For the first time, the deep n-well (DNW) depletion space of a High Voltage CMOS sensor has been characterized using a Transient Current Technique based on the simultaneous absorption of two photons. This novel approach has allowed to resolve the DNW implant boundaries and therefore to accurately determine the real depleted volume and the effective doping concentration of the substrate. The unprecedented spatial resolution of this new method comes from the fact that measurable free carrier generation in two photon mode only occurs in a micrometric scale voxel around the focus of the beam. Real three-dimensional spatial resolution is achieved by scanning the beam focus within the sample.

High-resolution three-dimensional imaging of a depleted CMOS sensor using an edge Transient Current Technique based on the Two Photon Absorption process (TPA-eTCT)

Energy Technology Data Exchange (ETDEWEB)

García, Marcos Fernández; Sánchez, Javier González; Echeverría, Richard Jaramillo [Instituto de Física de Cantabria (CSIC-UC), Avda. los Castros s/n, E-39005 Santander (Spain); Moll, Michael [CERN, Organisation europénne pour la recherche nucléaire, CH-1211 Genéve 23 (Switzerland); Santos, Raúl Montero [SGIker Laser Facility, UPV/EHU, Sarriena, s/n - 48940 Leioa-Bizkaia (Spain); Moya, David [Instituto de Física de Cantabria (CSIC-UC), Avda. los Castros s/n, E-39005 Santander (Spain); Pinto, Rogelio Palomo [Departamento de Ingeniería Electrónica, Escuela Superior de Ingenieros Universidad de Sevilla (Spain); Vila, Iván [Instituto de Física de Cantabria (CSIC-UC), Avda. los Castros s/n, E-39005 Santander (Spain)

2017-02-11

For the first time, the deep n-well (DNW) depletion space of a High Voltage CMOS sensor has been characterized using a Transient Current Technique based on the simultaneous absorption of two photons. This novel approach has allowed to resolve the DNW implant boundaries and therefore to accurately determine the real depleted volume and the effective doping concentration of the substrate. The unprecedented spatial resolution of this new method comes from the fact that measurable free carrier generation in two photon mode only occurs in a micrometric scale voxel around the focus of the beam. Real three-dimensional spatial resolution is achieved by scanning the beam focus within the sample.

Fano resonance in the absorption of two photons in crystal defects. Ressonancia de Fano na absorcao de dois fotons em defeitos cristalinos

Energy Technology Data Exchange (ETDEWEB)

Souza, G P

1984-01-01

The absorption of two photons in the electronic transition within the 4f/sup 7/ configuration which is superposed to the vibronic structure of the 4f/sup 7/ - 4f/sup 6/5d transition, is studied. The line shape with the Fano's formalism is described. The study was carried out on Eu/sup +2/ doped CaF/sub 2/. The experimental apparatus was built and the results obtained are in good agreement with the theoretical predictions.

Effects of conjugation length and resonance enhancement on two-photon absorption in phenylene–vinylene oligomers

DEFF Research Database (Denmark)

Johnsen, Mette; Paterson, M.J.; Arnbjerg, J.

2008-01-01

. This phenomenon of the so-called resonance enhancement allows for greater control in obtaining an optimal response when using existing two-photon chromophores, and provides a much-needed guide for the systematic development and efficient use of two-photon singlet oxygen sensitizers....

Pulse-bandwidth dependence of coherent phase control of resonance-mediated (2+1) three-photon absorption

International Nuclear Information System (INIS)

Gandman, Andrey; Chuntonov, Lev; Rybak, Leonid; Amitay, Zohar

2007-01-01

We study in detail coherent phase control of femtosecond resonance-mediated (2+1) three-photon absorption and its dependence on the spectral bandwidth of the excitation pulse. The regime is the weak-field regime of third perturbative order. The corresponding interference mechanism involves a group of three-photon excitation pathways that are on resonance with the intermediate state and a group of three-photon excitation pathways that are near resonant with it. The model system of the study is atomic sodium (Na), for which experimental and numerical-theoretical results are obtained. Prominent among the results is our finding that with simple proper pulse shaping an increase in the excitation bandwidth leads to a corresponding increase in the enhancement of the three-photon absorption over the absorption induced by the (unshaped) transform-limited pulse. For example, here, a 40 nm bandwidth leads to an order-of-magnitude enhancement over the transform-limited absorption

Phonon-assisted two-photon exciton transitions in semiconductors

International Nuclear Information System (INIS)

Hassan, A.R.

1987-08-01

The theory of phonon-assisted two-photon transitions to excitonic states in semiconductors has been theoretically investigated. The effects of both the nonparabolicity of the band and the degeneracy of the valence band have been taken into account. Expressions for the absorption coefficient through different band models are calculated. The numerical applications to CdI 2 and GaP show that the 4-band model gives the dominant contribution which leads to a final s-exciton state. An exciton peak appears at an energy which is close to that recently observed in CdI 2 . The non-parabolic effect enhances the absorption coefficient by a two-order of magnitude. (author). 6 refs, 1 fig., 1 tab

Effect of loss on slow-light enhanced absorption in liquid-infiltrated photonic crystals

DEFF Research Database (Denmark)

Pedersen, Jesper Goor; Xiao, Sanshui; Mortensen, Asger

2008-01-01

We study slow-light enhancement of absorption measurements in photonic crystals composed of lossy dielectrics. We find that the material loss has an unexpected limited drawback and may even increase the bandwidth for low-index contrast systems.......We study slow-light enhancement of absorption measurements in photonic crystals composed of lossy dielectrics. We find that the material loss has an unexpected limited drawback and may even increase the bandwidth for low-index contrast systems....

Jet cross sections in polarized photon-hadron collisions

CERN Document Server

de Florian, Daniel

1999-01-01

We present a computation of one- and two-jet cross sections in polarized photon-hadron collisions, which is accurate to next-to-leading order in QCD. Our results can be used to compute photoproduction cross sections in electron-proton scattering. To this purpose, we investigate the structure of the polarized Weizsaecker-Williams function, where we include a universal, non-logarithmic term, neglected in the literature. We construct a Monte Carlo code, within the framework of the subtraction method, and we use it to study the phenomenology of jet production in the energy range relevant to HERA. In particular, we investigate the perturbative stability of our results, and we discuss the possibility of constraining polarized parton densities of the proton and the photon using jet data.

Total Hadronic Cross-Section of Photon-Photon Interactions at LEP

CERN Document Server

Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barillari, T.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Feld, L.; Fiedler, F.; Fierro, M.; Fleck, I.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lawson, I.; Layter, J.G.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Polok, J.; Przybycien, M.; Quadt, A.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; Wetterling, D.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.

2000-01-01

The total hadronic cross-section sigma_gg(W) for the interaction of real photons, gg->hadrons, is measured for gg centre-of-mass energies 10 e+e-g*g* -> e+e- hardrons, using a luminosity function for the photon flux together with form factors for extrapolating to real photons (Q^2=0 GeV^2). The data were taken with the OPAL detector at LEP at e+e- centre-of-mass energies 161, 172 and 183 GeV. The cross-section sigma_gg(W) is compared with Regge factorisation and with the energy dependence observed in gp and pp interactions. The data are also compared to models which predict a faster rise of sigma_gg(W) compared to gp and pp interactions due to additional hard gg interactions not present in hadronic collisions.

A mitochondrial targeted two-photon iridium(III) phosphorescent probe for selective detection of hypochlorite in live cells and in vivo.

Science.gov (United States)

Li, Guanying; Lin, Qian; Sun, Lingli; Feng, Changsheng; Zhang, Pingyu; Yu, Bole; Chen, Yu; Wen, Ya; Wang, Hui; Ji, Liangnian; Chao, Hui

2015-01-01

Endogenous hypochlorite ion (ClO(-)) is a highly reactive oxygen species (ROS) that is produced from hydrogen peroxide and chloride ions catalyzed by myeloperoxidase (MPO). And mitochondrion is one of the major sources of ROS including ClO(-). In the present work, a two-photon phosphorescent probe for ClO(-) in mitochondria was developed. An iridium(III) complex bearing a diaminomaleonitrile group as ClO(-) reactive moiety specifically responded to ClO(-) over other ions and ROSs. When the probe was reacted with ClO(-) to form an oxidized carboxylate product, a significant enhancement in phosphorescence intensity was observed under one-photon (402 nm) and two-photon (750 nm) excitation, with a two-photon absorption cross-section of 78.1 GM at 750 nm. More importantly, ICP-MS results and cellular images co-stained with Mito-tracker Green demonstrated that this probe possessed high specificity for mitochondria. This probe was applied in the one- and two-photon imaging of ClO(-) in vitro and in vivo. The results suggested endotoxin lipopolysaccharide (LPS) induced ClO(-) mostly generated in the liver of zebrafish. Copyright © 2015 Elsevier Ltd. All rights reserved.

Atlas of photoneutron cross sections obtained with monoenergetic photons

International Nuclear Information System (INIS)

Dietrich, S.S.; Berman, B.L.

1988-01-01

Photoneutron cross-section and integrated cross-section data obtained with monoenergetic photons are presented in a uniform format. All of the measured partial photoneutron cross sections, the total photoneutron cross section, and the photoneutron yield cross section are plotted as functions of the incident photon energy, as are the integrated photoneutron cross sections and their first and second moments. The values of the integrated cross sections and the moments of the integrated total cross section up to the highest photon energy for which they were measured are tabulated, as are the parameters of Lorentz curves fitted to the total photoneutron cross-section data for medium and heavy nuclei (A>50). This compilation is current as of June 1987. copyright 1988 Academic Press, Inc

Studies of photoionization in liquids using a laser two-photon ionization conductivity technique

International Nuclear Information System (INIS)

Siomos, K.; Christophorou, L.G.

1981-01-01

One-photon ionization studies of solute molecules in a liquid medium are limited by the absorption of the host medium. A laser two-photon ionization (TPI) technique using a frequency tunable dye laser has been developed, whereby the photoionization threshold of a solute molecule was determined from the induced conductivity in the liquid medium under study due to electron-ion pair formation via two-photon ionization of the solute. The two-photon induced electron-ion current is measured as a function of the laser wavelength, lambda/sub laser/. In this paper, results are reported and discussed on the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), pyrene and fluoranthene in liquid n-pentane

Can Two-Photon Interference be Considered the Interference of Two Photons?

International Nuclear Information System (INIS)

Pittman, T.B.; Strekalov, D.V.; Migdall, A.; Rubin, M.H.; Sergienko, A.V.; Shih, Y.H.

1996-01-01

We report on a open-quote open-quote postponed compensation close-quote close-quote experiment in which the observed two-photon entangled state interference cannot be pictured in terms of the overlap of the two individual photon wave packets of a parametric down-conversion pair on a beam splitter. In the sense of a quantum eraser, the distinguishability of the different two-photon Feynman amplitudes leading to a coincidence detection is removed by delaying the compensation until after the output of an unbalanced two-photon interferometer. copyright 1996 The American Physical Society

NIR-emitting molecular-based nanoparticles as new two-photon absorbing nanotools for single particle tracking

Science.gov (United States)

Daniel, J.; Godin, A. G.; Clermont, G.; Lounis, B.; Cognet, L.; Blanchard-Desce, M.

2015-07-01

In order to provide a green alternative to QDs for bioimaging purposes and aiming at designing bright nanoparticles combining both large one- and two-photon brightness, a bottom-up route based on the molecular engineering of dedicated red to NIR emitting dyes that spontaneously form fluorescent organic nanoparticles (FONs) has been implemented. These fully organic nanoparticles built from original quadrupolar dyes are prepared using a simple, expeditious and green protocol that yield very small molecular-based nanoparticles (radius ~ 7 nm) suspension in water showing a nice NIR emission (λem=710 nm). These FONs typically have absorption coefficient more than two orders larger than popular NIR-emitting dyes (such as Alexa Fluor 700, Cy5.5 ….) and much larger Stokes shift values (i.e. up to over 5500 cm-1). They also show very large two-photon absorption response in the 800-1050 nm region (up to about 106 GM) of major promise for two-photon excited fluorescence microscopy. Thanks to their brightness and enhanced photostability, these FONs could be imaged as isolated nanoparticles and tracked using wide-field imaging. As such, thanks to their size and composition (absence of heavy metals), they represent highly promising alternatives to NIR-emitting QDs for use in bioimaging and single particle tracking applications. Moreover, efficient FONs coating was achieved by using a polymeric additive built from a long hydrophobic (PPO) and a short hydrophilic (PEO) segment and having a cationic head group able to interact with the highly negative surface of FONs. This electrostatically-driven interaction promotes both photoluminescence and two-photon absorption enhancement leading to an increase of two-photon brightness of about one order of magnitude. This opens the way to wide-field single particle tracking under two-photon excitation

Large conditional single-photon cross-phase modulation

Science.gov (United States)

Hosseini, Mahdi; Duan, Yiheng; Vuletić, Vladan

2016-01-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of π/6 (and up to π/3 by postselection on photons that remain in the system longer than average) between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. By upgrading to a state-of-the-art cavity, our system can reach a coherent phase shift of π at low loss, enabling deterministic and universal photonic quantum logic. PMID:27519798

Resonant metallic nanostructure for enhanced two-photon absorption in a thin GaAs p-i-n diode

Energy Technology Data Exchange (ETDEWEB)

Portier, Benjamin; Pardo, Fabrice; Péré-Laperne, Nicolas; Steveler, Emilie; Dupuis, Christophe; Bardou, Nathalie; Lemaître, Aristide; Pelouard, Jean-Luc, E-mail: jean-luc.pelouard@lpn.cnrs.fr [Laboratoire de Photonique et de Nanostructures (LPN-CNRS), Route de Nozay, 91460 Marcoussis (France); Vest, Benjamin; Jaeck, Julien; Rosencher, Emmanuel [ONERA The French Aerospace Lab, Chemin de la Hunière, F-91760 Palaiseau (France); Haïdar, Riad [ONERA The French Aerospace Lab, Chemin de la Hunière, F-91760 Palaiseau (France); École Polytechnique, Département de Physique, F-91128 Palaiseau (France)

2014-07-07

Degenerate two-photon absorption (TPA) is investigated in a 186 nm thick gallium arsenide (GaAs) p-i-n diode embedded in a resonant metallic nanostructure. The full device consists in the GaAs layer, a gold subwavelength grating on the illuminated side, and a gold mirror on the opposite side. For TM-polarized light, the structure exhibits a resonance close to 1.47 μm, with a confined electric field in the intrinsic region, far from the metallic interfaces. A 109 times increase in photocurrent compared to a non-resonant device is obtained experimentally, while numerical simulations suggest that both gain in TPA-photocurrent and angular dependence can be further improved. For optimized grating parameters, a maximum gain of 241 is demonstrated numerically and over incidence angle range of (−30°; +30°).

Resonant metallic nanostructure for enhanced two-photon absorption in a thin GaAs p-i-n diode

International Nuclear Information System (INIS)

Portier, Benjamin; Pardo, Fabrice; Péré-Laperne, Nicolas; Steveler, Emilie; Dupuis, Christophe; Bardou, Nathalie; Lemaître, Aristide; Pelouard, Jean-Luc; Vest, Benjamin; Jaeck, Julien; Rosencher, Emmanuel; Haïdar, Riad

2014-01-01

Degenerate two-photon absorption (TPA) is investigated in a 186 nm thick gallium arsenide (GaAs) p-i-n diode embedded in a resonant metallic nanostructure. The full device consists in the GaAs layer, a gold subwavelength grating on the illuminated side, and a gold mirror on the opposite side. For TM-polarized light, the structure exhibits a resonance close to 1.47 μm, with a confined electric field in the intrinsic region, far from the metallic interfaces. A 109 times increase in photocurrent compared to a non-resonant device is obtained experimentally, while numerical simulations suggest that both gain in TPA-photocurrent and angular dependence can be further improved. For optimized grating parameters, a maximum gain of 241 is demonstrated numerically and over incidence angle range of (−30°; +30°).

Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

Energy Technology Data Exchange (ETDEWEB)

Rana, Amit Kumar; Kumar, Yogendra; Arjunan, M.S.; Sen, Somaditya; Shirage, Parasharam M., E-mail: pmshirage@iiti.ac.in, E-mail: paras.shirage@gmail.com [Department of Physics, Indian Institute of Technology Indore, Simrol Campus, Khandwa Road, Indore 452020 (India); Centre of Materials Science and Engineering, Indian Institute of Technology Indore, Simrol Campus, Khandwa Road, Indore 452020 (India); J, Aneesh; Adarsh, K. V. [Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023 (India)

2015-12-07

In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips.

Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

International Nuclear Information System (INIS)

Rana, Amit Kumar; Kumar, Yogendra; Arjunan, M.S.; Sen, Somaditya; Shirage, Parasharam M.; J, Aneesh; Adarsh, K. V.

2015-01-01

In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips

Two-photon physics

International Nuclear Information System (INIS)

Bardeen, W.A.

1981-10-01

A new experimental frontier has recently been opened to the study of two photon processes. The first results of many aspects of these reactions are being presented at this conference. In contrast, the theoretical development of research ito two photon processes has a much longer history. This talk reviews the many different theoretical ideas which provide a detailed framework for our understanding of two photon processes

Inclusive two-jet production in photon-photon collisions: Direct and resolved contributions in next-to-leading order QCD

International Nuclear Information System (INIS)

Kleinwort, T.; Kramer, G.

1996-10-01

We have calculated inclusive two-jet production in photon-photon collisions superimposing direct, single-resolved and double-resolved cross sections for center-of-mass energies of TRISTAN and LEP1.5. All three contributions are calculated up to next-to-leading order. The results are compared with recent experimental data. Three NLO sets of parton distributions of the photon are tested. (orig.)

Efficient non-linear two-photon effects from the Cesium 6D manifold

Science.gov (United States)

Haluska, Nathan D.; Perram, Glen P.; Rice, Christopher A.

2018-02-01

We report several non-linear process that occur when two-photon pumping the cesium 6D states. Cesium vapor possess some of the largest two-photon pump cross sections in nature. Pumping these cross sections leads to strong amplified spontaneous emission that we observe on over 17 lasing lines. These new fields are strong enough to couple with the pump to create additional tunable lines. We use a heat pipe with cesium densities of 1014 to 1016 cm-3 and 0 to 5 Torr of helium buffer gas. The cesium 6D States are interrogated by both high energy pulses and low power CW sources. We observe four-wave mixing, six-wave mixing, potential two-photon lasing, other unknown nonlinear processes, and the persistence of some processes at low thresholds. This system is also uniquely qualified to support two-photon lasing under the proper conditions.

Measurement of the Cross Section for open b-Quark Production in Two-Photon Interactions at LEP

CERN Document Server

Schael, S.; Bruneliere, R.; De Bonis, I.; Decamp, D.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocme, B.; Bravo, S.; Casado, M.P.; Chmeissani, M.; Crespo, J.M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; De Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmuller, O.; Cattaneo, M.; Clerbaux, B.; Drevermann, H.; Forty, R.W.; Frank, M.; Gianotti, F.; Hansen, J.B.; Harvey, J.; Hutchcroft, D.E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J.M.; Perret, P.; Hansen, J.D.; Hansen, J.R.; Hansen, P.H.; Kraan, A.C.; Nilsson, B.S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rouge, A.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G.P.; Passalacqua, L.; Kennedy, J.; Lynch, J.G.; Negus, P.; O'Shea, V.; Thompson, A.S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E.E.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P.J.; Girone, M.; Marinelli, N.; Nowell, J.; Rutherford, S.A.; Sedgbeer, J.K.; Thompson, J.C.; White, R.; Ghete, V.M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C.K.; Clarke, D.P.; Ellis, G.; Finch, A.J.; Foster, F.; Hughes, G.; Jones, R.W.L.; Pearson, M.R.; Robertson, N.A.; Sloan, T.; Smizanska, M.; van der Aa, O.; Delaere, C.; Leibenguth, G.; Lemaitre, V.; Blumenschein, U.; Holldorfer, F.; Jakobs, K.; Kayser, F.; Muller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Huttmann, K.; Lutjens, G.; Manner, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Azzurri, P.; Bagliesi, Giuseppe; Boccali, T.; Foa, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciaba, A.; Sguazzoni, G.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P.G.; Awunor, O.; Blair, G.A.; Cowan, G.; Garcia-Bellido, A.; Green, M.G.; Medcalf, T.; Misiejuk, A.; Strong, J.A.; Teixeira-Dias, P.; Clifft, R.W.; Edgecock, T.R.; Norton, P.R.; Tomalin, I.R.; Ward, J.J.; Bloch-Devaux, Brigitte; Boumediene, D.; Colas, P.; Fabbro, B.; Lancon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, B.; Litke, A.M.; Taylor, G.; Booth, C.N.; Cartwright, S.; Combley, F.; Hodgson, P.N.; Lehto, M.; Thompson, L.F.; Bohrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S.R.; Berkelman, K.; Cranmer, K.; Ferguson, D.P.S.; Gao, Y.; Gonzalez, S.; alez; Hayes, O.J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P.A., III; Nielsen, J.; Pan, Y.B.; von Wimmersperg-Toeller, J.H.; Wiedenmann, W.; Wu, J.; Wu, Sau Lan; Wu, X.; Zobernig, G.; Dissertori, G.

2007-01-01

Inclusive \\beauty-quark production in two-photon collisions has been measured at LEP using an integrated luminosity of $698\\mathrm{pb}^{-1}\\,$ collected by the ALEPH detector with $\\sqrt{s}$ between 130 and 209 \\GeV . The b quarks were identified using lifetime information. The cross section is found to be \\[ \\mathrm{ \\sigma(e^+ e^- \\rightarrow e^+ e^- b \\bar{b}\\, X) = (5.4\\pm 0.8\\,_{stat} \\pm 0.8\\,_{syst}} )\\,\\mathrm{pb},\\] which is consistent with Next-to-Leading Order QCD.

Employing X-ray absorption technique for better detector resolution and measurement of low cross-section events

Science.gov (United States)

Sharma, Gaurav; Puri, Nitin K.; Kumar, Pravin; Nandi, T.

2018-03-01

The versatility of X-ray absorption technique is experimentally employed for enhancing the detector resolution and to rejuvenate the low probable transitions obscured in the pile-up region, during a beam-foil spectroscopy experiment. The multiple aluminum absorber layers (10 μm each) are used to suppress the pile-up contribution drastically and to restore a weak transition which is about 1.38 × 104 times weaker than a one-electron-one-photon transitions viz. Kα and Khα. The weak line is possibly originating from a two-electron-one-photon transition in He-like Ti. Further, the transitions, which were obscured in the spectra due to high intensity ratio, are revived by dissimilar line intensity attenuation using this technique. The measured lifetimes of Kα line with and without intensity attenuation match well within error bar. The present technique finds potential implications in understanding the structure of multiple-core-vacant ions and other low cross section processes in ion-solid collisions.

Characterization of Photon-Counting Detector Responsivity for Non-Linear Two-Photon Absorption Process

Science.gov (United States)

Sburlan, S. E.; Farr, W. H.

2011-01-01

Sub-band absorption at 1550 nm has been demonstrated and characterized on silicon Geiger mode detectors which normally would be expected to have no response at this wavelength. We compare responsivity measurements to singlephoton absorption for wavelengths slightly above the bandgap wavelength of silicon (approx. 1100 microns). One application for this low efficiency sub-band absorption is in deep space optical communication systems where it is desirable to track a 1030 nm uplink beacon on the same flight terminal detector array that monitors a 1550 nm downlink signal for pointingcontrol. The currently observed absorption at 1550 nm provides 60-70 dB of isolation compared to the response at 1064 nm, which is desirable to avoid saturation of the detector by scattered light from the downlink laser.

Fluorenyl benzothiadiazole and benzoselenadiazole near-IR fluorescent probes for two-photon fluorescence imaging (Conference Presentation)

Science.gov (United States)

Belfield, Kevin D.; Yao, Sheng; Kim, Bosung; Yue, Xiling

2016-03-01

Imaging biological samples with two-photon fluorescence (2PF) microscopy has the unique advantage of resulting high contrast 3D resolution subcellular image that can reach up to several millimeters depth. 2PF probes that absorb and emit at near IR region need to be developed. Two-photon excitation (2PE) wavelengths are less concerned as 2PE uses wavelengths doubles the absorption wavelength of the probe, which means 2PE wavelengths for probes even with absorption at visible wavelength will fall into NIR region. Therefore, probes that fluoresce at near IR region with high quantum yields are needed. A series of dyes based on 5-thienyl-2, 1, 3-benzothiadiazole and 5-thienyl-2, 1, 3-benzoselenadiazole core were synthesized as near infrared two-photon fluorophores. Fluorescence maxima wavelengths as long as 714 nm and fluorescence quantum yields as high as 0.67 were achieved. The fluorescence quantum yields of the dyes were nearly constant, regardless of solvents polarity. These diazoles exhibited large Stokes shift (GM), and high two-photon fluorescence figure of merit (FM , 1.04×10-2 GM). Cells incubated on a 3D scaffold with one of the new probes (encapsulated in Pluronic micelles) exhibited bright fluorescence, enabling 3D two-photon fluorescence imaging to a depth of 100 µm.

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

Prediction of e± elastic scattering cross-section ratio based on phenomenological two-photon exchange corrections

Science.gov (United States)

Qattan, I. A.

2017-06-01

I present a prediction of the e± elastic scattering cross-section ratio, Re+e-, as determined using a new parametrization of the two-photon exchange (TPE) corrections to electron-proton elastic scattering cross section σR. The extracted ratio is compared to several previous phenomenological extractions, TPE hadronic calculations, and direct measurements from the comparison of electron and positron scattering. The TPE corrections and the ratio Re+e- show a clear change of sign at low Q2, which is necessary to explain the high-Q2 form factors discrepancy while being consistent with the known Q2→0 limit. While my predictions are in generally good agreement with previous extractions, TPE hadronic calculations, and existing world data including the recent two measurements from the CLAS and VEPP-3 Novosibirsk experiments, they are larger than the new OLYMPUS measurements at larger Q2 values.

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.

The Density Matrix for Single-mode Light after k-Photon Absorption

Science.gov (United States)

Voigt, H.; Bandilla, A.

In order to continue and generalize the studies of the density matrix of a light field undergoing k-photon absorption, in this paper we put the emphasis on the off-diagonal elements. The solution obtained earlier for the diagonal elements describing the photon statistics can be found as a special case but will not be discussed again. The general solution calculated by recursion shows an asymptotic behaviour if the initial photon number is sufficiently high. Only the initial phase information survives. Illustrating the solution we start with coherent light and a generalized coherent state.Translated AbstractDie Dichtematrix eines Lichtstrahls nach k-Photonen-Absorption aus einer ModeWir führen die Betrachtungen über das Verhalten der Dichtematrix eines Lichtfeldes nach k-Photonen-Absorption aus einer Mode verallgemeinernd weiter und konzentrieren uns auf die Nichtdiagonalelemente. Die im folgenden angegebene allgemeine Lösung, die durch Rekursion gefunden wurde, enthält die schon früher erhaltene, jedoch hier nicht weiter diskutierte Lösung für die Diagonalelemente als Spezialfall. Sie zeigt ferner, daß es einen asymptotischen Zustand gibt, der eine von der Ausgangsintensität unabhängige Information über die Ausgangsphase enthält. Zur Diskussion der Lösung werden verschiedene Anfangsbedingungen betrachtet, so z. B. kohärentes Licht und kohärentes Licht, das ein Medium mit nichtlinearem Brechungsindex durchlaufen hat (Kerr-Effekt).

Particle Production in Two-Photon Collisions at Belle

International Nuclear Information System (INIS)

Nakazawa, Hideyuki

2010-01-01

Experimental study of η η production in two-photon collisions: The differential cross section for the process γ γ → η η has been measured in the kinematic range above the η η threshold, 1.096 GeV -1 data sample collected with the Belle detector at the KEKB e + e - collider. In the W range 1.1-2.0 GeV/c 2 we perform an analysis of resonance amplitudes for various partial waves; at higher energy we extract the contributions of χ cJ charmonia and compare the energy and angular dependence of the cross section with the predictions of theoretical models. Observation of η c (2S) in six-prong final states produced in two-photon collisions: We report the observation of η c (2S), produced in two-photon collisions, and decaying to the six-prong final states 3(π + π - ), K + K - 2(π + π - ), and K 0 S K + ππ + π - (including the charge-conjugate state). This analysis is based on a large data sample accumulated by the Belle experiment at the KEKB asymmetric-energy electron-positron collider. This is the first observation of decay modes of the η c (2S) other than K 0 S K + π - . (author)

Wideband absorption in one dimensional photonic crystal with graphene-based hyperbolic metamaterials

Science.gov (United States)

Kang, Yongqiang; Liu, Hongmei

2018-02-01

A broadband absorber which was proposed by one dimensional photonic crystal (1DPC) containing graphene-based hyperbolic metamaterials (GHMM) is theoretically investigated. For TM mode, it was demonstrated to absorb roughly 90% of all available electromagnetic waves at a 14 THz absorption bandwidth at normal incidence. The absorption bandwidth was affected by Fermi energy and thickness of dielectric layer. When the incident angle was increased, the absorption value decreased, and the absorption band had a gradual blue shift. These findings have potential applications for designing broadband optoelectronic devices at mid-infrared and THz frequency range.

Mid-IR Absorption Cross-Section Measurements of Hydrocarbons

KAUST Repository

Alrefae, Majed Abdullah

2013-01-01

-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform

A microprocessor controlled system for pulsed laser experiments nad its applications in two photon absorption spectroscopy of CaF2: Eu+2

International Nuclear Information System (INIS)

Nunes, L.A.O.; Matinaga, F.M.; Castro, J.C. de

1986-01-01

A very low cost data station for pulsed dye laser aplications is developed. The system employs a low cost single board microcomputer and low cost componenets. Details on the hardware configuration and sofware are presented. In order to demonstrate the power of this system we employed it to obtain a two photon absorption spectrum of some f→f transitions in europium ions present as impurity in CaF 2 . Flexibility of hardware and software allow other aplications, such as transient recording in the 10nsec per channel range and other real time data processing. (Author) [pt

Controllable Absorption and Dispersion Properties of an RF-driven Five-Level Atom in a Double-Band Photonic-Band-Gap Material

International Nuclear Information System (INIS)

Ding Chunling; Li Jiahua; Yang Xiaoxue

2011-01-01

The probe absorption-dispersion spectra of a radio-frequency (RF)-driven five-level atom embedded in a photonic crystal are investigated by considering the isotropic double-band photonic-band-gap (PBG) reservoir. In the model used, the two transitions are, respectively, coupled by the upper and lower bands in such a PBG material, thus leading to some curious phenomena. Numerical simulations are performed for the optical spectra. It is found that when one transition frequency is inside the band gap and the other is outside the gap, there emerge three peaks in the absorption spectra. However, for the case that two transition frequencies lie inside or outside the band gap, the spectra display four absorption profiles. Especially, there appear two sharp peaks in the spectra when both transition frequencies exist inside the band gap. The influences of the intensity and frequency of the RF-driven field on the absorptive and dispersive response are analyzed under different band-edge positions. It is found that a transparency window appears in the absorption spectra and is accompanied by a very steep variation of the dispersion profile by adjusting system parameters. These results show that the absorption-dispersion properties of the system depend strongly on the RF-induced quantum interference and the density of states (DOS) of the PBG reservoir. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Synthesis of novel fluorene-based two-photon absorbing molecules and their applications in optical data storage, microfabrication, and stimulated emission depletion

Science.gov (United States)

Yanez, Ciceron

2009-12-01

Two-photon absorption (2PA) has been used for a number of scientific and technological applications, exploiting the fact that the 2PA probability is directly proportional to the square of the incident light intensity (while one-photon absorption bears a linear relation to the incident light intensity). This intrinsic property of 2PA leads to 3D spatial localization, important in fields such as optical data storage, fluorescence microscopy, and 3D microfabrication. The spatial confinement that 2PA enables has been used to induce photochemical and photophysical events in increasingly smaller volumes and allowed nonlinear, 2PA-based, technologies to reach sub-diffraction limit resolutions. The primary focus of this dissertation is the development of novel, efficient 2PA, fluorene-based molecules to be used either as photoacid generators (PAGs) or fluorophores. A second aim is to develop more effective methods of synthesizing these compounds. As a third and final objective, the new molecules were used to develop a write-once-read many (WORM) optical data storage system, and stimulated emission depletion probes for bioimaging. In Chapter I, the microwave-assisted synthesis of triarylsulfonium salt photoacid generators (PAGs) from their diphenyliodonium counterparts is reported. The microwave-assisted synthesis of these novel sulfonium salts afforded reaction times 90 to 420 times faster than conventional thermal conditions, with photoacid quantum yields of new sulfonium PAGs ranging from 0.01 to 0.4. These PAGs were used to develop a fluorescence readout-based, nonlinear three-dimensional (3D) optical data storage system (Chapter II). In this system, writing was achieved by acid generation upon two-photon absorption (2PA) of a PAG (at 710 or 730 nm). Readout was then performed by interrogating two-photon absorbing dyes, after protonation, at 860 nm. Two-photon recording and readout of voxels was demonstrated in five and eight consecutive, crosstalk-free layers within a

Experimental Studies of the Mechanism of Photon Absorption on Light Nuclei

Energy Technology Data Exchange (ETDEWEB)

Morrow, Steven A. [Univ. of Edinburgh, Scotland (United Kingdom)

2000-09-13

A measurement of the reaction ¹²C(γ,pγ') has been made with tagged photons in the range 49.47 < E _γ < 70.24 MeV. The relative population of a triplet of states, (7/2^-, 1/2⁺, 5/2⁺) at E_ex ≅ 7 MeV in the residual nucleus ¹¹B, following the reaction ¹²C(γ,p), has been made by directly resolving their de-excitation γ-ray decay to the ground state of ¹¹B. This measurement constitutes the highest resolution ever achieved in determining the excitation function of the residual nucleus after a (γ,p) reaction (~ 48 keV FWHM at E_ex ≅ 7 MeV). Comparison has been made with the data of Kuzin et al, who also measured the relative populations with a resolution of ~ 270 keV at E_ex ≅ 7 MeV. The 7/2^- state at 6.74 MeV has been observed to be the most strongly excited state of the triplet in agreement with Kuzin et al. Disagreement has been found for the relative strengths of the 1/2⁺ and 5/2⁺ states in the triplet. An estimation of the maximum effect of angular correlations between the ejected proton and de-excitation γ-ray has been included in the analysis. This effect increases the disagreement between the measurements. A study of the reaction ¹²C(e,e'p) has been made in the missing momentum region 260 < p_m < 320 MeV/c. A Rosenbluth separation of the reaction cross section has been carried out in parallel kinematics to measure the structure functions W_L and W_T. The experimental data have been compared with Complete Distorted Wave Impulse Approximation calculations and Random Phase Approximation calculations. The latter when including virtual photon absorption on 2-body currents (Meson Exchange Currents + Isobar Currents) are seen to describe the reduced cross sections better than 1-body current or Complete Distorted Wave Impulse Approximation calculations. For the

The γ total cross section and the photon structure functions

International Nuclear Information System (INIS)

Alexander, G.

1986-01-01

A review on the current experimental status of the photon-photon total hadronic cross section as a function of energy and Q 2 is given in addition to the results obtained for the leptonic and hadronic photon structure functions. The results are discussed in terms of the point-like part of the photon and non-perturbative VDM part. It is shown that the cross section at Q 2 = 0 is well described by VDM derived models

Two-photon fluorescence and fluorescence imaging of two styryl heterocyclic dyes combined with DNA.

Science.gov (United States)

Gao, Chao; Liu, Shu-yao; Zhang, Xian; Liu, Ying-kai; Qiao, Cong-de; Liu, Zhao-e

2016-03-05

Two new styryl heterocyclic two-photon (TP) materials, 4-[4-(N-methyl)styrene]-imidazo [4,5-f][1,10] phenanthroline-benzene iodated salt (probe-1) and 4,4-[4-(N-methyl)styrene]-benzene iodated salt (probe-2) were successfully synthesized and studied as potential fluorescent probes of DNA detection. The linear and nonlinear photophysical properties of two compounds in different solvents were investigated. The absorption, one- and two-photon fluorescent spectra of the free dye and dye-DNA complex were also examined to evaluate their photophysical properties. The binding constants of dye-DNA were obtained according to Scatchard equation with good values. The results showed that two probes could be used as fluorescent DNA probes by two-photon excitation, and TP fluorescent properties of probe-1 are superior to that of probe-2. The fluorescent method date indicated that the mechanisms of dye-DNA complex interaction may be groove binding for probe-1 and electrostatic interaction for probe-2, respectively. The MTT assay experiments showed two probes are low toxicity. Moreover, the TP fluorescence imaging of DNA detection in living cells at 800 nm indicated that the ability to locate in cell nuclei of probe-1 is better than that of probe-2. Copyright © 2015 Elsevier B.V. All rights reserved.

Deterministic reshaping of single-photon spectra using cross-phase modulation.

Science.gov (United States)

Matsuda, Nobuyuki

2016-03-01

The frequency conversion of light has proved to be a crucial technology for communication, spectroscopy, imaging, and signal processing. In the quantum regime, it also offers great potential for realizing quantum networks incorporating disparate physical systems and quantum-enhanced information processing over a large computational space. The frequency conversion of quantum light, such as single photons, has been extensively investigated for the last two decades using all-optical frequency mixing, with the ultimate goal of realizing lossless and noiseless conversion. I demonstrate another route to this target using frequency conversion induced by cross-phase modulation in a dispersion-managed photonic crystal fiber. Owing to the deterministic and all-optical nature of the process, the lossless and low-noise spectral reshaping of a single-photon wave packet in the telecommunication band has been readily achieved with a modulation bandwidth as large as 0.4 THz. I further demonstrate that the scheme is applicable to manipulations of a nonclassical frequency correlation, wave packet interference, and entanglement between two photons. This approach presents a new coherent frequency interface for photons for quantum information processing.

Entanglement concentration and purification of two-mode squeezed microwave photons in circuit QED

Science.gov (United States)

Zhang, Hao; Alsaedi, Ahmed; Hayat, Tasawar; Deng, Fu-Guo

2018-04-01

We present a theoretical proposal for a physical implementation of entanglement concentration and purification protocols for two-mode squeezed microwave photons in circuit quantum electrodynamics (QED). First, we give the description of the cross-Kerr effect induced between two resonators in circuit QED. Then we use the cross-Kerr media to design the effective quantum nondemolition (QND) measurement on microwave-photon number. By using the QND measurement, the parties in quantum communication can accomplish the entanglement concentration and purification of nonlocal two-mode squeezed microwave photons. We discuss the feasibility of our schemes by giving the detailed parameters which can be realized with current experimental technology. Our work can improve some practical applications in continuous-variable microwave-based quantum information processing.

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

Parameterization and generation of photon-induced K cross-sections

International Nuclear Information System (INIS)

Bansal, Meenakshi; Mittal, Raj

2010-01-01

Theoretical K-shell photoionization and K X-ray fluorescence (K XRF) cross sections have been fitted empirically in polynomials of photon energy E and atomic number Z. This has been used to develop a computer code KCSPIF to generate K-shell photo-ionization and K XRF cross-sections for any element in the range 5≤Z≤95 and for photon energies, above K-edge-1500 keV, when only the atomic number and photon energy are supplied as the input.

Two-photon interference of polarization-entangled photons in a Franson interferometer.

Science.gov (United States)

Kim, Heonoh; Lee, Sang Min; Kwon, Osung; Moon, Han Seb

2017-07-18

We present two-photon interference experiments with polarization-entangled photon pairs in a polarization-based Franson-type interferometer. Although the two photons do not meet at a common beamsplitter, a phase-insensitive Hong-Ou-Mandel type two-photon interference peak and dip fringes are observed, resulting from the two-photon interference effect between two indistinguishable two-photon probability amplitudes leading to a coincidence detection. A spatial quantum beating fringe is also measured for nondegenerate photon pairs in the same interferometer, although the two-photon states have no frequency entanglement. When unentangled polarization-correlated photons are used as an input state, the polarization entanglement is successfully recovered through the interferometer via delayed compensation.

Restricted mass energy absorption coefficients for use in dosimetry

International Nuclear Information System (INIS)

Brahme, A.

1977-02-01

When matter is irradiated by a photon beam the fraction of energy absorbed locally in some region Rsub(Δ) (where the size of the region Rsub(Δ) is related to the range of secondary electrons of some restriction energy Δ) is expressed by the restricted mass energy absorption coefficient. In this paper an example is given of how restricted mass energy absorption coefficients can be calculated from existing differential photon interaction cross sections. Some applications of restricted mass absorption coefficients in dosimetry are also given. (B.D.)

Simultaneous control of emission localization and two-photon absorption efficiency in dissymmetrical chromophores

International Nuclear Information System (INIS)

Tretiak, Sergei

2009-01-01

The aim of the present work is to demonstrate that combined spectral tuning of fluorescence and two-photon absorption (TPA) properties of multipolar chromophores can be achieved by introduction of slight electronic chemical dissymmetry. In that perspective, two novel series of structurally related chromophores have been designed and studied: a first series based on rod-like quadrupolar chromophores bearing different electron-donating (D) end groups and a second series based on three-branched octupolar chromophores built from a trigonal donating moiety and bearing various acceptor (A) peripheral groups. The influence of the electronic dissymmetry is investigated by combined experimental and theoretical studies of the linear and nonlinear optical properties of dissymmetric chromophores compared to their symmetrical counterparts. In both types of systems (i.e. quadrupoles and octupoles) experiments and theory reveal that excitation is essentially delocalized and that excitation involves synchronized charge redistribution between the different D and A moieties within the multipolar structure (i.e. concerted intramolecular charge transfer). In contrast, the emission stems only from a particular dipolar subunit bearing the strongest D or A moieties due to fast excitation localization after excitation prior to emission. Hence control of emission characteristics (polarization and emission spectrum) in addition to localization can be achieved by controlled introduction of electronic dissymmetry (i.e. replacement of one of the D or A end-groups by a slightly stronger D(prime) or A(prime) units). Interestingly dissymmetrical functionalization of both quadrupolar and octupolar compounds does not lead to significant loss in TPA responses and can even be beneficial due to the spectral broadening and peak position tuning that it allows. This study thus reveals an original molecular engineering route strategy allowing major TPA enhancement in multipolar structures due to concerted

Experimental demonstration of a four-port photonic crystal cross-waveguide structure

DEFF Research Database (Denmark)

Yu, Yi; Heuck, Mikkel; Ek, Sara

2012-01-01

We report the design and fabrication of a four-port InP photonic crystal cavity-waveguide structure in which two crossing waveguides intersect in a cavity. Transmission measurements show that by exploiting mode-gap effects, high cross-talk suppression between the two waveguides can be obtained. I....... In addition, the waveguides couple to two distinct cavity resonances with different quality-factors as well as small mode volumes. This structure is promising for realizing ultra-fast, low-energy optical switches or memories....

An analysis of MCNP cross-sections and tally methods for low-energy photon emitters.

Science.gov (United States)

Demarco, John J; Wallace, Robert E; Boedeker, Kirsten

2002-04-21

Monte Carlo calculations are frequently used to analyse a variety of radiological science applications using low-energy (10-1000 keV) photon sources. This study seeks to create a low-energy benchmark for the MCNP Monte Carlo code by simulating the absolute dose rate in water and the air-kerma rate for monoenergetic point sources with energies between 10 keV and 1 MeV. The analysis compares four cross-section datasets as well as the tally method for collision kerma versus absorbed dose. The total photon attenuation coefficient cross-section for low atomic number elements has changed significantly as cross-section data have changed between 1967 and 1989. Differences of up to 10% are observed in the photoelectric cross-section for water at 30 keV between the standard MCNP cross-section dataset (DLC-200) and the most recent XCOM/NIST tabulation. At 30 keV, the absolute dose rate in water at 1.0 cm from the source increases by 7.8% after replacing the DLC-200 photoelectric cross-sections for water with those from the XCOM/NIST tabulation. The differences in the absolute dose rate are analysed when calculated with either the MCNP absorbed dose tally or the collision kerma tally. Significant differences between the collision kerma tally and the absorbed dose tally can occur when using the DLC-200 attenuation coefficients in conjunction with a modern tabulation of mass energy-absorption coefficients.

Direct and indirect two-photon processes in semiconductors

International Nuclear Information System (INIS)

Hassan, A.R.

1986-07-01

The expressions describing direct and indirect two-photon absorption in crystals are given. They are valid both near and far from the energy gap. A perturbative approach through two different band models is adopted. The effects of the non-parabolicity and the degeneracy of the energy bands are considered. The numerical results are compared with the other theories and with a recent experimental data in Zn and AgCl. It is shown that the dominant transition mechanisms are of the allowed-allowed type near and far from the gap for both direct and indirect processes. (author)

An organic dye with very large Stokes-shift and broad tunability of fluorescence: Potential two-photon probe for bioimaging and ultra-sensitive solid-state gas sensor

Energy Technology Data Exchange (ETDEWEB)

He, Tingchao; Tian, Xiaoqing; Lin, Xiaodong, E-mail: linxd@szu.edu.cn, E-mail: hdsun@ntu.edu.sg [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Wang, Yue; Zhao, Xin; Sun, Handong, E-mail: linxd@szu.edu.cn, E-mail: hdsun@ntu.edu.sg [Division of Physics and Applied Physics, and Centre for Disruptive Photonic Technologies (CDPT), School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore); Gao, Yang; Grimsdale, Andrew C. [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2016-01-04

Light-emitting nonlinear optical molecules, especially those with large Stokes shifts and broad tunability of their emission wavelength, have attracted considerable attention for various applications including biomedical imaging and fluorescent sensors. However, most fluorescent chromophores have only limited potential for such applications due to small Stokes shifts, narrow tunability of fluorescence emissions, and small optical nonlinearity in highly polar solvents. In this work, we demonstrate that a two-photon absorbing stilbene chromophore exhibits a large two-photon absorption action cross-section (ηδ = 320 GM) in dimethylsulfoxide (DMSO) and shows broad fluorescence tunability (125 nm) by manipulating the polarity of the surrounding medium. Importantly, a very large Stokes shift of up to 227 nm is achieved in DMSO. Thanks to these features, this chromophore can be utilized as a two-photon probe for bioimaging applications and in an ultrasensitive solid-state gas detector.

Development of a two-wavelength IR laser absorption diagnostic for propene and ethylene

Science.gov (United States)

Parise, T. C.; Davidson, D. F.; Hanson, R. K.

2018-05-01

A two-wavelength infrared laser absorption diagnostic for non-intrusive, simultaneous quantitative measurement of propene and ethylene was developed. To this end, measurements of absorption cross sections of propene and potential interfering species at 10.958 µm were acquired at high-temperatures. When used in conjunction with existing absorption cross-section measurements of ethylene and other species at 10.532 µm, a two-wavelength diagnostic was developed to simultaneously measure propene and ethylene, the two small alkenes found to generally dominate the final decomposition products of many fuel hydrocarbon pyrolysis systems. Measurements of these two species is demonstrated using this two-wavelength diagnostic scheme for propene decomposition between 1360 and 1710 K.

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

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...

The general expression for the transition amplitude of two-photon ionization of atomic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Karule, E [Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina Boulevard 19, Riga, LV-1586 (Latvia); Moine, B [Universite Paris Sud, 91405 Orsay Cedex (France)

2003-05-28

Two-photon ionization of atomic hydrogen with an excess photon is revisited. The non-relativistic dipole approximation and Coulomb Green function (CGF) formalism are applied. Using the CGF Sturmian expansion straightforwardly, one gets the radial transition amplitude in the form of an infinite sum over Gauss hypergeometric functions which are polynomials. It is convergent if all intermediate states are in the discrete spectrum. In the case of two-photon ionization with an excess photon, when photoionization is also possible, intermediate states are in the continuum. We performed the explicit summation over intermediate states and got a simple general expression for the radial transition amplitude in the form of a finite sum over Appell hypergeometric functions, which are not polynomials. An Appell function may be expressed as an infinite sum over Gauss functions. In the case of ionization by an excess photon, Gauss functions are transformed to give a convergent radial transition amplitude for the whole region. The generalized cross sections for two-photon above-threshold ionization of atomic hydrogen in the ground state and excited states calculated by us agree very well with results of previous calculations. Generalized cross sections for two-photon ionization of positronium in the ground state are obtained by scaling those for atomic hydrogen.

Coherent enhancement of resonance-mediated multiphoton absorption

International Nuclear Information System (INIS)

Zhang, Shian; Zhang, Hui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-01-01

In this paper, we theoretically investigate the coherent enhancement of resonance-mediated (2+2) four-photon absorption. It is found that by shaping the spectral phase with a π phase step, the resonance-mediated (2+2) four-photon transition probability can be enhanced. Furthermore, the coherent enhancement dependences on the detuning between the two two-photon absorptions, laser spectral bandwidth and laser centre frequency are explicitly discussed and analysed. We believe these theoretical results may play an important role in enhancing more complex resonance-mediated multiphoton absorption processes.

Measurements of the effective thermal neutron absorption cross-section in multi-grain models

International Nuclear Information System (INIS)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Schneider, K.; Woznicka, U.

2005-01-01

The effective macroscopic absorption cross-section Σ a eff of thermal neutrons in a grained medium differs from the corresponding cross-section Σ a hom in the homogeneous medium consisting of the same components, contributing in the same amounts. The ratio of these cross-sections defines the grain parameter, G, which is a measure of heterogeneity of the system for neutron absorption. Heterogeneous models have been built as two- or three-component systems (Ag, Cu and Co 3 O 4 grains distributed in a regular grid in Plexiglas, in various proportions between them). The effective absorption cross-section has been measured and the experimental grain parameter has been found for each model. The obtained values are in the interval 0.34 < G < 0.58, while G = 1 means the homogeneous material. (author)

UV-Vis Ratiometric Resonance Synchronous Spectroscopy for Determination of Nanoparticle and Molecular Optical Cross Sections.

Science.gov (United States)

Nettles, Charles B; Zhou, Yadong; Zou, Shengli; Zhang, Dongmao

2016-03-01

Demonstrated herein is a UV-vis Ratiometric Resonance Synchronous Spectroscopic (R2S2, pronounced as "R-two-S-two" for simplicity) technique where the R2S2 spectrum is obtained by dividing the resonance synchronous spectrum of a NP-containing solution by the solvent resonance synchronous spectrum. Combined with conventional UV-vis measurements, this R2S2 method enables experimental quantification of the absolute optical cross sections for a wide range of molecular and nanoparticle (NP) materials that range optically from pure photon absorbers or scatterers to simultaneous photon absorbers and scatterers, simultaneous photon absorbers and emitters, and all the way to simultaneous photon absorbers, scatterers, and emitters in the UV-vis wavelength region. Example applications of this R2S2 method were demonstrated for quantifying the Rayleigh scattering cross sections of solvents including water and toluene, absorption and resonance light scattering cross sections for plasmonic gold nanoparticles, and absorption, scattering, and on-resonance fluorescence cross sections for semiconductor quantum dots (Qdots). On-resonance fluorescence quantum yields were quantified for the model molecular fluorophore Eosin Y and fluorescent Qdots CdSe and CdSe/ZnS. The insights and methodology presented in this work should be of broad significance in physical and biological science research that involves photon/matter interactions.

Two-photon double ionization of the helium atom by ultrashort pulses

International Nuclear Information System (INIS)

Palacios, Alicia; Horner, Daniel A.; Rescigno, Thomas N.; McCurdy, C. William

2010-01-01

Two-photon double ionization of the helium atom was the subject of early experiments at FLASH and will be the subject of future benchmark measurements of the associated electron angular and energy distributions. As the photon energy of a single femtosecond pulse is raised from the threshold for two-photon double ionization at 39.5 eV to beyond the sequential ionization threshold at 54.4 eV, the electron ejection dynamics change from the highly correlated motion associated with nonsequential absorption to the much less correlated sequential ionization process. The signatures of both processes have been predicted in accurate ab initio calculations of the joint angular and energy distributions of the electrons, and those predictions contain some surprises. The dominant terms that contribute to sequential ionization make their presence apparent several eV below that threshold. In two-color pump probe experiments with short pulses whose central frequencies require that the sequential ionization process necessarily dominates, a two-electron interference pattern emerges that depends on the pulse delay and the spin state of the atom.

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.

Two photon processes in surface photovoltage spectroscopy

International Nuclear Information System (INIS)

Craig, R.P.; Thurgate, S.M.

1996-01-01

Full text: A significant mid-gap effect has been found in Surface Photovoltage Spectroscopy measurements of cleaved GaAs, InP and Si wafer which is normally interpreted as arising from transitions between surface states and band edges. This large mid-gap effect common to various materials is puzzling as such a high proportion of mid-gap states seems unlikely. Most theories of surface states predict states that tail from the band edges into the gap or states that have a well defined energy in the gap. None propose a large state exactly at E G /2. We recently investigated the variation in SPS spectra with flux density. We find a non-linear correlation in the magnitude of Band-Bending arising from mid-gap and band-gap photon energies. We suggest that the mid-gap feature is due to a two photon absorption process leading to carrier pair generation mediated by mid-gap states in the continuum of band-gap surface states

Multiphoton absorption coefficients in solids: an universal curve

International Nuclear Information System (INIS)

Brandi, H.S.; Araujo, C.B. de

1983-04-01

An universal curve for the frequency dependence of the multiphoton absorption coefficient is proposed based on a 'non-perturbative' approach. Specific applications have been made to obtain two, three, four and five photons absorption coefficient in different materials. Properly scaling of the two photon absorption coefficient and the use of the universal curve yields results for the higher order absorption coefficients in good agreement with the experimental data. (Author) [pt

Cross section and linear polarization of tagged photons

International Nuclear Information System (INIS)

Asai, J.; Caplan, H.S.; Skopik, D.M.; DelBianco, W.; Maximon, L.C.

1988-01-01

Formulae for bremsstrahlung cross sections and polarizations are usually presented in coordinate systems not very suitable for application by experimental physicists to devices such as photon-tagging monochromators. In this paper the transformations between the different coordinate systems are presented, along with examples of the calculated cross sections and polarizations in a form convenient from the experimental standpoint. These examples also give the predicted characteristics of the photon tagger currently under construction at the Saskatchewan Accelerator Laboratory. (16 refs., 19 figs., tab.)

Two-photon exchange in elastic electron-nucleon scattering

International Nuclear Information System (INIS)

Blunden, P.G.; Melnitchouk, W.; Tjon, J.A.

2005-01-01

A detailed study of two-photon exchange in unpolarized and polarized elastic electron-nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio, G E /G M . The two-photon exchange contribution to the longitudinal polarization transfer P L is small, whereas the contribution to the transverse polarization transfer P T is enhanced at backward angles by several percent, increasing with Q 2 . This gives rise to a small, E /G M obtained from the polarization transfer ratio P T /P L at large Q 2 . We also compare the two-photon exchange effects with data on the ratio of e + p to e - p cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron and estimate the elastic intermediate state contribution to the 3 He form factors

Hadron production in photon-photon collisions

International Nuclear Information System (INIS)

Pandita, P.N.; Singh, Y.

1976-01-01

We analyze deep-inelastic photon-photon collisions via the two-photon mechanism in electron-positron (-electron) colliding beams in a form especially suitable for experimental analysis. It is shown that by a helicity analysis similar to that used in electroproduction experiments, we can separate five of the eight structure functions describing the process γ* + γ* → hadrons. The helicity cross sections for this process and for the process with one real photon (inelastic electron-photon scattering) are related to structure functions, and are evaluated using quark light-cone algebra. There are anomalous contributions to the structure functions for the inelastic electron-photon scattering which arise both in parton as well as generalized vector-meson-dominance models. This suggests a connection between these two types of models for photon-photon scattering. Further, we use vector-meson dominance to construct a sum rule for sigma/sub gamma//sub gamma/ /sub arrow-right/ from which it is estimated that roughly 20% of the cross section should be built up from higher-mass vector states. Using a spectral representation for the total transverse cross section, and the ''aligned-jet'' vector-dominance model we achieve a connection, via a ''correspondence principle,'' with the parton model for the hadron multiplicities in photon-photon collisions. We also comment on inclusive pion multiplicities and the approach to scaling for photon-photon processes in the light-cone algebra

Positron two-photon annihilation coincidence technique: difference mode

Energy Technology Data Exchange (ETDEWEB)

Karol, P J; Klobuchar, R L [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Chemistry

1978-05-01

A difference (or comparative) mode in the measurement of two-photon coincidences from positron or positronium annihilation has been developed. The method can be used to advantage, particularly in gases, in determining annihilation parameters such as quenching cross sections for low concentration strongly quenching chemical species in a reference medium which is relatively non-quenching.

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.

Inclusive two-photon reactions at TRISTAN

International Nuclear Information System (INIS)

Drees, M.

1995-01-01

After briefly reviewing past accomplishments of TRISTAN experiments in the field of inclusive two-photon reactions, I discuss open problems in the Monte Carlo simulation of such reactions. The main emphasis is on multiple scattering, i.e. events where at least two pairs of partons scatter within the same γγ collision to form at least four (mini)jets. The cross section for such events might just be observable at TRISTAN. While theoretical arguments for the existence of such events are strong, they have not yet been directly observed experimentally, thereby potentially opening a new opportunity for TRISTAN experiments. (author)

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)

Production mechanism of atomic nitrogen in atmospheric pressure pulsed corona discharge measured using two-photon absorption laser-induced fluorescence

International Nuclear Information System (INIS)

Teramoto, Yoshiyuki; Ono, Ryo; Oda, Tetsuji

2012-01-01

To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N 2 discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N 2 discharge pulse is estimated to be 2.9 - 9.8 × 10 13 atoms and the energy efficiency of atomic nitrogen production is estimated to be about 1.8 - 6.1 × 10 16 atoms/J. The energy efficiency of atomic nitrogen production in N 2 discharge is constant against the discharge energy, while that in N 2 /O 2 discharge increases with discharge energy. In the N 2 /O 2 discharge, two-step process of N 2 dissociation plays significant role for atomic nitrogen production.

Two-dimensional topological photonics

Science.gov (United States)

Khanikaev, Alexander B.; Shvets, Gennady

2017-12-01

Originating from the studies of two-dimensional condensed-matter states, the concept of topological order has recently been expanded to other fields of physics and engineering, particularly optics and photonics. Topological photonic structures have already overturned some of the traditional views on wave propagation and manipulation. The application of topological concepts to guided wave propagation has enabled novel photonic devices, such as reflection-free sharply bent waveguides, robust delay lines, spin-polarized switches and non-reciprocal devices. Discrete degrees of freedom, widely used in condensed-matter physics, such as spin and valley, are now entering the realm of photonics. In this Review, we summarize the latest advances in this highly dynamic field, with special emphasis on the experimental work on two-dimensional photonic topological structures.

Inclusive photon cross section at 13 TeV

CERN Document Server

Cueto , Ana; The ATLAS collaboration

2017-01-01

Measurements of prompt photon production in proton-proton collisions provide a testing ground for perturbative QCD with a hard colourless probe. This kind of measurements were recently used to investigate novel approaches to the description of parton radiation, showcasing the importance of resummation of threshold logarithms in QCD and of electroweak corrections, further they are also sensitive at leading order to the gluon density in the proton. ATLAS has made public very recently the first measurements of inclusive photon production in the new kinematic regime opened by the 13 TeV collisions with an integrated luminosity of 3.2 fb^{-1}. The inclusive photo-production cross section is measured as a function of the photon transverse energy above 125 GeV in different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the measured cross section and provide an adequate description of the data.

Photon scattering by the giant dipole resonance

International Nuclear Information System (INIS)

Bowles, T.J.; Holt, R.J.; Jackson, H.E.; McKeown, R.D.; Specht, J.R.

1979-01-01

Although many features of the giant dipole resonance are well known, the coupling between the basic dipole oscillation and other nuclear collective degrees of freedom such as surface vibrations and rotations is poorly understood. This aspect was investigated by elastic and inelastic bremsstrahlung scattering of tagged photons over the energy range 15 to 22 MeV. Target nuclei were 60 Ni, 52 Cr, 56 Fe, 92 Mo, and 96 Mo. Scattering and absorption cross sections are tabulated, along with parameters obtained from a two-Lorentzian analysis of the scattering cross sections; measured spectra are shown. It was necessary to remove Thomson scattering from the experimental results. It was found that coupling to surface vibrations in the giant dipole resonance is much weaker than the dynamic collective model suggests. The elastic scattering cross section for all targets but 60 Ni showed structure that is not evident in the absorption cross section measurement. 12 figures, 2 tables

Photonic devices based on patterning by two photon induced polymerization techniques

Science.gov (United States)

Fortunati, I.; Dainese, T.; Signorini, R.; Bozio, R.; Tagliazucca, V.; Dirè, S.; Lemercier, G.; Mulatier, J.-C.; Andraud, C.; Schiavuta, P.; Rinaldi, A.; Licoccia, S.; Bottazzo, J.; Franco Perez, A.; Guglielmi, M.; Brusatin, G.

2008-04-01

Two and three dimensional structures with micron and submicron resolution have been achieved in commercial resists, polymeric materials and sol-gel materials by several lithographic techniques. In this context, silicon-based sol-gel materials are particularly interesting because of their versatility, chemical and thermal stability, amount of embeddable active compounds. Compared with other micro- and nano-fabrication schemes, the Two Photon Induced Polymerization is unique in its 3D processing capability. The photopolymerization is performed with laser beam in the near-IR region, where samples show less absorption and less scattering, giving rise to a deeper penetration of the light. The use of ultrashort laser pulses allows the starting of nonlinear processes like multiphoton absorption at relatively low average power without thermally damaging the samples. In this work we report results on the photopolymerization process in hybrid organic-inorganic films based photopolymerizable methacrylate-containing Si-nanobuilding blocks. Films, obtained through sol-gel synthesis, are doped with a photo-initiator allowing a radical polymerization of methacrylic groups. The photo-initiator is activated by femtosecond laser source, at different input energies. The development of the unexposed regions is performed with a suitable solvent and the photopolymerized structures are characterized by microscopy techniques.

Photoelectric absorption cross sections with variable abundances

Science.gov (United States)

Balucinska-Church, Monika; Mccammon, Dan

1992-01-01

Polynomial fit coefficients have been obtained for the energy dependences of the photoelectric absorption cross sections of 17 astrophysically important elements. These results allow the calculation of X-ray absorption in the energy range 0.03-10 keV in material with noncosmic abundances.

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).

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)

Measurement of differential di-photon plus jet cross sections using the ATLAS detector

Energy Technology Data Exchange (ETDEWEB)

Bessner, Martin Florian

2017-08-15

A good understanding of the strong interaction is crucial for every experiment at a hadron collider. Events with photons provide a direct access to study processes of the strong interaction. This thesis presents the measurement of differential cross sections of events with two photons as a function of the number of hadronic jets. Photons are required to be isolated from hadronic activity in the event. Collision data is used corresponding to an integrated luminosity of 20.3 fb{sup -1} at a proton-proton collision energy of √(s)=8 TeV collected by the ATLAS detector at the Large Hadron Collider (LHC) in 2012. The dominant background contribution comes from hadronic jets which are identified as photons, occurring mainly when a π{sup 0} carries most of the jet energy. Two methods to remove this contribution are presented. A smaller background contribution arising from electrons misidentified as photons is removed as well. The measured event yields are corrected for detector inefficiencies and resolution effects. An unfolding method based on singular value decomposition of the resolution matrix is extended to two-dimensional distributions and applied to the reconstructed distributions. All systematic uncertainties are evaluated, the dominant uncertainties arise from the jet background subtraction and the uncertainty in the jet energy scale. 16 observables are studied to explore the photon and jet kinematics. Double differential cross sections are shown as function of those observables and the number of jets, both inclusively (≥n jets) and exclusively (=n jets). The results are compared to theoretical predictions from Sherpa, Pythia and GoSam.

Measurement of differential di-photon plus jet cross sections using the ATLAS detector

International Nuclear Information System (INIS)

Bessner, Martin Florian

2017-08-01

A good understanding of the strong interaction is crucial for every experiment at a hadron collider. Events with photons provide a direct access to study processes of the strong interaction. This thesis presents the measurement of differential cross sections of events with two photons as a function of the number of hadronic jets. Photons are required to be isolated from hadronic activity in the event. Collision data is used corresponding to an integrated luminosity of 20.3 fb"-"1 at a proton-proton collision energy of √(s)=8 TeV collected by the ATLAS detector at the Large Hadron Collider (LHC) in 2012. The dominant background contribution comes from hadronic jets which are identified as photons, occurring mainly when a π"0 carries most of the jet energy. Two methods to remove this contribution are presented. A smaller background contribution arising from electrons misidentified as photons is removed as well. The measured event yields are corrected for detector inefficiencies and resolution effects. An unfolding method based on singular value decomposition of the resolution matrix is extended to two-dimensional distributions and applied to the reconstructed distributions. All systematic uncertainties are evaluated, the dominant uncertainties arise from the jet background subtraction and the uncertainty in the jet energy scale. 16 observables are studied to explore the photon and jet kinematics. Double differential cross sections are shown as function of those observables and the number of jets, both inclusively (≥n jets) and exclusively (=n jets). The results are compared to theoretical predictions from Sherpa, Pythia and GoSam.

Photon management in two-dimensional disordered media.

Science.gov (United States)

Vynck, Kevin; Burresi, Matteo; Riboli, Francesco; Wiersma, Diederik S

2012-12-01

Elaborating reliable and versatile strategies for efficient light coupling between free space and thin films is of crucial importance for new technologies in energy efficiency. Nanostructured materials have opened unprecedented opportunities for light management, notably in thin-film solar cells. Efficient coherent light trapping has been accomplished through the careful design of plasmonic nanoparticles and gratings, resonant dielectric particles and photonic crystals. Alternative approaches have used randomly textured surfaces as strong light diffusers to benefit from their broadband and wide-angle properties. Here, we propose a new strategy for photon management in thin films that combines both advantages of an efficient trapping due to coherent optical effects and broadband/wide-angle properties due to disorder. Our approach consists of the excitation of electromagnetic modes formed by multiple light scattering and wave interference in two-dimensional random media. We show, by numerical calculations, that the spectral and angular responses of thin films containing disordered photonic patterns are intimately related to the in-plane light transport process and can be tuned through structural correlations. Our findings, which are applicable to all waves, are particularly suited for improving the absorption efficiency of thin-film solar cells and can provide a new approach for high-extraction-efficiency light-emitting diodes.

Low temperature characterization of the photocurrent produced by two-photon transitions in a quantum dot intermediate band solar cell

International Nuclear Information System (INIS)

Antolin, E.; Marti, A.; Stanley, C.R.; Farmer, C.D.; Canovas, E.; Lopez, N.; Linares, P.G.; Luque, A.

2008-01-01

Conceived to exceed the conversion efficiency of conventional photovoltaic devices, the intermediate band solar cell bases its operation on exploiting, besides the usual band-to-band optical transitions, the absorption of two sub-bandgap photons. For the present, the only technology used to implement an intermediate band in real devices has been the growth of an InAs/GaAs quantum dot superlattice. In practice, the obtained material shows two limitations: the narrow energy gap between conduction and intermediate band and the appearance of growth defects due to the lattice stress. The consequences are the presence of non-radiative recombination mechanisms and the thermal escape of electrons from the intermediate to the conduction band, hindering the splitting of the quasi-Fermi levels associated with the intermediate and conduction bands and the observation of photocurrent associated with the two-photon absorption. By reducing the temperature at which the devices are characterised we have suppressed the parasitic thermal mechanisms and have succeeded in measuring the photocurrent caused by the absorption of two below bandgap photons. In this work, the characterization of this photocurrent at low temperature is presented and discussed

Selective two-photon excitation of a vibronic state by correlated photons.

Science.gov (United States)

Oka, Hisaki

2011-03-28

We theoretically investigate the two-photon excitation of a molecular vibronic state by correlated photons with energy anticorrelation. A Morse oscillator having three sets of vibronic states is used, as an example, to evaluate the selectivity and efficiency of two-photon excitation. We show that a vibrational mode can be selectively excited with high efficiency by the correlated photons, without phase manipulation or pulse-shaping techniques. This can be achieved by controlling the quantum correlation so that the photon pair concurrently has two pulse widths, namely, a temporally narrow width and a spectrally narrow width. Though this concurrence is seemingly contradictory, we can create such a photon pair by tailoring the quantum correlation between two photons.

Broadband and high absorption in Fibonacci photonic crystal including MoS2 monolayer in the visible range

Science.gov (United States)

Ansari, Narges; Mohebbi, Ensiyeh

2018-03-01

2D molybdenum disulfide MoS2, has represented potential applications in optoelectronic devices based on their promising optical absorption responses. However, for practical applications, absorption should increase furthermore in a wide wavelength window. In this paper, we design Fibonacci photonic crystals (PCs) based on Si, SiO2 and MoS2 monolayer and we calculate their absorption responses based on the transfer matrix method. The optical refractive index of the MoS2 monolayer was determined based on the Lorentz-Drude-Gauss model. Effects of Fibonacci order, periodicity, incident light angle and polarization are included in our calculations. Finally, an absorption as large as 90% in a wide optical wavelength range is achieved for both polarizations and incident angle down to 60°. Our results are useful for designing photonic devices with high absorption efficiency.

Two-dimensional 'photon fluid': effective photon-photon interaction and physical realizations

International Nuclear Information System (INIS)

Chiao, R Y; Hansson, T H; Leinaas, J M; Viefers, S

2004-01-01

We describe a recently developed effective theory for atom-mediated photon-photon interactions in a two-dimensional 'photon fluid' confined to a Fabry-Perot resonator. The photons in the lowest longitudinal cavity mode will appear as massive bosons interacting via a renormalized delta-function potential with a strength determined by physical parameters such as the density of atoms and the detuning of the photons relative to the resonance frequency of the atoms. We discuss novel quantum phenomena for photons, such as Bose-Einstein condensation and bound state formation, as well as possible experimental scenarios based on Rydberg atoms in a microwave cavity, or alkali atoms in an optical cavity

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.

Meson production in two-photon interactions at LHC energies

Energy Technology Data Exchange (ETDEWEB)

Da Silva, D. T.; Goncalves, V. P.; Sauter, W. K. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Campus Universitario UFPel, CP 354, 96010-900, Capao do Leao-RS (Brazil)

2013-03-25

The LHC opens a new kinematical regime at high energy, where several questions related to the description of the high-energy regime of the Quantum Chromodynamics (QCD) remain without satisfactory answers. Some open questions are the search for non-q-bar q resonances, the determination of the spectrum of q-bar q states and the identification of states with anomalous {gamma}{gamma} couplings. A possible way to study these problems is the study of meson production in two-photon interactions. In this contribution we calculate the meson production in two-photon interactions at LHC energies considering proton - proton collisions and estimate the total cross section for the production of the mesons {pi}, a, f, {eta} and {chi}.

Magnetic absorption of VHE photons in the magnetosphere of the Crab pulsar

Science.gov (United States)

Bogovalov, S. V.; Contopoulos, I.; Prosekin, A.; Tronin, I.; Aharonian, F. A.

2018-05-01

The detection of the pulsed ˜1 TeV gamma-ray emission from the Crab pulsar reported by MAGIC and VERITAS collaborations demands a substantial revision of existing models of particle acceleration in the pulsar magnetosphere. In this regard model independent restrictions on the possible production site of the very high energy (VHE) photons become an important issue. In this paper, we consider limitations imposed by the process of conversion of VHE gamma-rays into e± pairs in the magnetic field of the pulsar magnetosphere. Photons with energies exceeding 1 TeV are effectively absorbed even at large distances from the surface of the neutron star. Our calculations of magnetic absorption in the force-free magnetosphere show that the twisting of the magnetic field due to the pulsar rotation makes the magnetosphere more transparent compared to the dipole magnetosphere. The gamma-ray absorption appears stronger for photons emitted in the direction of rotation than in the opposite direction. There is a small angular cone inside which the magnetosphere is relatively transparent and photons with energy 1.5 TeV can escape from distances beyond 0.1 light cylinder radius (Rlc). The emission surface from where photons can be emitted in the observer's direction further restricts the sites of VHE gamma-ray production. For the observation angle 57° relative to the Crab pulsar axis of rotation and the orthogonal rotation, the emission surface in the open field line region is located as close as 0.4 Rlc from the stellar surface for a dipole magnetic field, and 0.1 Rlc for a force-free magnetic field.

Measurements of the effective total and resonance absorption cross sections for zircaloy-2 and zirconium

Energy Technology Data Exchange (ETDEWEB)

Kocic, A; Markovic, V [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1967-04-15

Zirconium and zircaloy-2 alloy, as constructive materials, have found wide application in reactor technology, especially in heavy water systems for two reasons: a) low neutron absorption cross section, b) good mechanical properties. The thickness of the zirconium and zircaloy-2 for different applications varies from several tenths of a millimeter to about ten millimeters. Therefore, to calculate reactor systems it is desirable to know the effective neutron absorption cross section for the range of thicknesses mention above. The thermal neutron cross sections for these materials are low and no appreciable variation of the effective neutron cross section occurs even for the largest thicknesses. However, this is not true for effective resonance absorption. On the other hand, due to the lack of detailed knowledge of the zirconium resonances, calculations of the effective resonance integrals cannot be performed. Therefore it is necessary to measure the effective total and resonance absorption cross section for zirconium (author)

Multifunctional biocompatible graphene oxide quantum dots decorated magnetic nanoplatform for efficient capture and two-photon imaging of rare tumor cells.

Science.gov (United States)

Shi, Yongliang; Pramanik, Avijit; Tchounwou, Christine; Pedraza, Francisco; Crouch, Rebecca A; Chavva, Suhash Reddy; Vangara, Aruna; Sinha, Sudarson Sekhar; Jones, Stacy; Sardar, Dhiraj; Hawker, Craig; Ray, Paresh Chandra

2015-05-27

Circulating tumor cells (CTCs) are extremely rare cells in blood containing billions of other cells. The selective capture and identification of rare cells with sufficient sensitivity is a real challenge. Driven by this need, this manuscript reports the development of a multifunctional biocompatible graphene oxide quantum dots (GOQDs) coated, high-luminescence magnetic nanoplatform for the selective separation and diagnosis of Glypican-3 (GPC3)-expressed Hep G2 liver cancer tumor CTCs from infected blood. Experimental data show that an anti-GPC3-antibody-attached multifunctional nanoplatform can be used for selective Hep G2 hepatocellular carcinoma tumor cell separation from infected blood containing 10 tumor cells/mL of blood in a 15 mL sample. Reported data indicate that, because of an extremely high two-photon absorption cross section (40530 GM), an anti-GPC3-antibody-attached GOQDs-coated magnetic nanoplatform can be used as a two-photon luminescence platform for selective and very bright imaging of a Hep G2 tumor cell in a biological transparency window using 960 nm light. Experimental results with nontargeted GPC3(-) and SK-BR-3 breast cancer cells show that multifunctional-nanoplatform-based cell separation, followed by two-photon imaging, is highly selective for Hep G2 hepatocellular carcinoma tumor cells.

Effects of autoionizing states on two-photon double ionization of the H2 molecule

International Nuclear Information System (INIS)

Guan, Xiaoxu; Bartschat, Klaus; Koesterke, Lars; Schneider, Barry I

2014-01-01

We report angle-resolved and angle-integrated cross sections for two-photon double-ionization of H by a strong laser pulse. The effect of doubly excited states on the predicted cross sections is addressed.

Monte Carlo simulation of photon scattering in x-ray absorption imaging of high-intensity discharge lamps

Energy Technology Data Exchange (ETDEWEB)

Curry, J J, E-mail: jjcurry@nist.go [National Institute of Standards and Technology, Gaithersburg, MD 20899-8422 (United States)

2010-06-16

Coherent and incoherent scattering of x-rays during x-ray absorption imaging of high-intensity discharge lamps have been studied with Monte Carlo simulations developed specifically for this purpose. The Monte Carlo code is described and some initial results are discussed. Coherent scattering, because of its angular concentration in the forward direction, is found to be the most significant scattering mechanism. Incoherent scattering, although comparably strong, is not as significant because it results primarily in photons being scattered in the rearward direction and therefore out of the detector. Coherent scattering interferes with the detected absorption signal because the path of a scattered photon through the object to be imaged is unknown. Although scattering is usually a small effect, it can be significant in regions of high contrast. At the discharge/wall interface, as many as 50% of the detected photons are scattered photons. The effect of scattering on analysis of Hg distributions has not yet been quantified.

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

One-photon two-electron processes in helium close to the double ionization threshold

International Nuclear Information System (INIS)

Bouri, C.

2007-04-01

This work presents a study of the 1 P 0 excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He + , owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the single continuum. This extension allows us to compute cross sections of single photoionization with or without excitation up to n 50 for an excess of 100 meV just above the double ionization threshold. A deep insight into this process is given by a partial waves analysis. The results obtained shed light on the key role of angular and radial correlations. The numerous data we obtain on double and single ionization allow us to establish a continuity relation between these two processes. We show that single ionization with an infinite excitation of the residual ion merges into double photoionization when the excess energy is redistributed between the two electrons. It appears that this relation is valid not only for low but also for high photon energies. Since the HRM-SOW can produce the integrated cross section for double photoionization with high accuracy in the low energy domain, we check the Wannier threshold law. The parameters extracted support strongly this threshold law, and are in good agreement with experimental

Mid-IR Absorption Cross-Section Measurements of Hydrocarbons

KAUST Repository

Alrefae, Majed Abdullah

2013-05-01

Laser diagnostics are fast-response, non-intrusive and species-specific tools perfectly applicable for studying combustion processes. Quantitative measurements of species concentration and temperature require spectroscopic data to be well-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform Infrared (FTIR) spectrometer, tunable Difference Frequency Generation laser and fixed wavelength helium-neon laser. The studied species are methane, methanol, acetylene, ethylene, ethane, ethanol, propylene, propane, 1-butene, n-butane, n-pentane, n-hexane, and n-heptane. The Fourier Transform Infrared (FTIR) spectrometer is used for the measurements of the absorption cross-sections and the integrated band intensities of the 13 hydrocarbons. The spectral region of the spectra is 2800 – 3400 cm-1 (2.9 – 3.6 μm) and the temperature range is 673 – 1100 K. These valuable data provide huge opportunities to select interference-free wavelengths for measuring time-histories of a specific species in a shock tube or other combustion systems. Such measurements can allow developing/improving chemical kinetics mechanisms by experimentally determining reaction rates. The Difference Frequency Generation (DFG) laser is a narrow line-width, tunable laser in the 3.35 – 3.53 μm wavelength region which contains strong absorption features for most hydrocarbons due to the fundamental C-H vibrating stretch. The absorption cross-sections of propylene are measured at seven different wavelengths using the DFG laser. The temperature range is 296 – 460 K which is reached using a Reflex Cell. The DFG laser is very attractive for kinetic studies in the shock tube because of its fast time response and the potential possibility of making species-specific measurements. The Fixed wavelength

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.

Multi-Photon Absorption Spectra: A Comparison Between Transmittance Change and Fluorescence Methods

Science.gov (United States)

2015-05-21

AFRL-OSR-VA-TR-2015-0134 multi-photon absorption spectra Cleber Mendonca INSTITUTO DE FISICA DE SAO CARLOS Final Report 05/21/2015 DISTRIBUTION A...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Instituto de Fisica de Sao Carlos - Universidade de Sao Paulo Av

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.

Multiply excited molecules produced by photon and electron interactions

International Nuclear Information System (INIS)

Odagiri, T.; Kouchi, N.

2006-01-01

The photon and electron interactions with molecules resulting in the formation of multiply excited molecules and the subsequent decay are subjects of great interest because the independent electron model and Born-Oppenheimer approximation are much less reliable for the multiply excited states of molecules than for the ground and lower excited electronic states. We have three methods to observe and investigate multiply excited molecules: 1) Measurements of the cross sections for the emission of fluorescence emitted by neutral fragments in the photoexcitation of molecules as a function of incident photon energy [1-3], 2) Measurements of the electron energy-loss spectra tagged with the fluorescence photons emitted by neutral fragments [4], 3) Measurements of the cross sections for generating a pair of photons in absorption of a single photon by a molecule as a function of incident photon energy [5-7]. Multiply excited states degenerate with ionization continua, which make a large contribution in the cross section curve involving ionization processes. The key point of our methods is hence that we measure cross sections free from ionization. The feature of multiply excited states is noticeable in such a cross section curve. Recently we have measured: i) the cross sections for the emission of the Lyman- fluorescence in the photoexcitation of CH 4 as a function of incident photon energy in the range 18-51 eV, ii) the electron energy-loss spectrum of CH 4 tagged with the Lyman-photons at 80 eV incident electron energy and 10 electron scattering angle in the range of the energy loss 20-45 eV, in order to understand the formation and decay of the doubly excited methane in photon and electron interactions. [8] The results are summarized in this paper and the simultaneous excitation of two electrons by electron interaction is compared with that by photon interaction in terms of the oscillator strength. (authors)

The polarization-angular structure and elliptical dichroism of the cross sections for three-photon bound-bound transitions in atoms

International Nuclear Information System (INIS)

Manakov, N.L.; Merem'yanin, A.V.

1997-01-01

Using the electric dipole approximation, we present, in invariant form, the cross section of an arbitrary three-photon transition between the discrete states of an atom with total angular momenta J i and J f . The cross section contains scalar and mixed products of the photon polarization vectors, and invariant atomic parameters dependent only on the photon frequencies. We determine the number of independent atomic parameters at fixed values of J i and J f and obtain their explicit expressions in terms of the reduced composite dipole matrix elements. The polarization dependence of the cross sections is expressed in terms of the degrees l and ξ of linear and circular photon polarizations. We analyze the phenomenon of dissipation-induced circular dichroism in three-photon processes, i.e., the difference Δ of the cross sections for opposite signs of the degree of circular polarization of all the photons. We study in detail the case of two identical photons and the phenomenon of elliptical dichroism, when Δ∼lξ holds and dichroism occurs only when the photons are elliptically polarized, with 0< vertical bar ξ vertical bar <1. Finally, we discuss the dissipation-induced effects of atom polarization in three-photon processes involving linearly polarized or unpolarized photons

Two-photon interference : spatial aspects of two-photon entanglement, diffraction, and scattering

NARCIS (Netherlands)

Peeters, Wouter Herman

2010-01-01

This dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena in various optical systems. Spatially entangled photon pairs are produced via the nonlinear optical

Absolute absorption cross-section and photolysis rate of I2

Directory of Open Access Journals (Sweden)

A. Saiz-Lopez

2004-01-01

Full Text Available Following recent observations of molecular iodine (I2 in the coastal marine boundary layer (MBL (Saiz-Lopez and Plane, 2004, it has become important to determine the absolute absorption cross-section of I2 at reasonably high resolution, and also to evaluate the rate of photolysis of the molecule in the lower atmosphere. The absolute absorption cross-section (σ of gaseous I2 at room temperature and pressure (295K, 760Torr was therefore measured between 182 and 750nm using a Fourier Transform spectrometer at a resolution of 4cm-1 (0.1nm at λ=500nm. The maximum absorption cross-section in the visible region was observed at λ=533.0nm to be σ=(4.24±0.50x10-18cm2molecule-1. The spectrum is available as supplementary material accompanying this paper. The photo-dissociation rate constant (J of gaseous I2 was also measured directly in a solar simulator, yielding J(I2=0.12±0.03s-1 for the lower troposphere. This is in excellent agreement with the value of 0.12±0.015s-1 calculated using the measured absorption cross-section, terrestrial solar flux for clear sky conditions and assuming a photo-dissociation yield of unity. A two-stream radiation transfer model was then used to determine the variation in photolysis rate with solar zenith angle (SZA, from which an analytic expression is derived for use in atmospheric models. Photolysis appears to be the dominant loss process for I2 during daytime, and hence an important source of iodine atoms in the lower atmosphere.

Two-photon contributions to the elastic electron-nucleon scattering in the Skyrme model; Zwei-Photon-Beitraege zur elastischen Elektron-Nukleon-Streuung im Skyrme-Modell

Energy Technology Data Exchange (ETDEWEB)

Kuhn, Markus

2008-09-23

The electromagnetic form factors are crucial for our understanding of the inner structure of the proton. Recently it has become feasible to measure them by the use of polarisation transfer techniques in addition to the traditional Rosenbluth separation method. Thereby emerged an incompatibility of the results obtained by these two different experimental methods. It is commonly assumed that the discrepance is induced by higher order corrections to the cross section, especially through two-photon exchange processes. Unfortunately these processes cannot be calculated in a model independent manner because off-shell photon nucleon vertices arise. Effective chiral lagrangians contain already local two-photon couplings and therefore seem exceptionally well suited to study the anomaly contribution to the two-photon exchange. These couplings give two-photon exchange contributions that can be understood as the coupling of the nucleon to pions, decaying into two virtual photons. A particular contribution emerges from the chiral anomaly of QCD, that describes the two-photon decay of the neutral pion. The most important goal of this work is the calculation of the contribution arising from the anomaly to the elastic electron-proton scattering. The results are expected to be widely model independent since the anomaly directly reflects a QCD property. Based on the Skyrme model the protons are realized as soliton solutions in effective chiral theories. The next to leading order contribution to the cross section is given by the interference between the one- and two-photon exchange. The latter contains an ultraviolet divergence, which is renormalized by a local effective counterterm. This counterterm contributes to the width of the neutral pion decay which determines the finite part of the counterterm coefficient. The affect of the anomaly to the Rosenbluth separation of the electromagnetic form factors as well as the discrepance regarding the polarization measurements is extensively

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.

A new interpretation of the two-photon entangled experiments via quantum mirrors

International Nuclear Information System (INIS)

Ion, D.B.; Constantin, P.

1997-01-01

The spontaneous parametric down conversion (SPDC) is a nonlinear optical process in which a laser pump beam (p) incident on a nonlinear crystal leads to the emission of a correlated pair of photons (signal (s) and idler (i)). In this process, energy and momentum of photons are conserved. Recently, the process allowed to demonstrate two photon 'ghost' imaging and 'ghost' interference diffraction patterns as well as other new phenomena from the geometric and physical optics. In this paper we consider that the key for understanding all of above results is given by the following two distinctive features of the SPDC crystals: 1 - the Cherenkov-like coherence conditions of the signal (or idler) photon; 2 - the existence of the crossing symmetric processes: p + s → i, p + i → s, as real processes in the SPDC crystals which can be described by the same transitions amplitude as that of the original SPDC process. Hence, the SPDC crystals can act as real mirrors (quantum mirror) since by the crossing processes and signal photon s(ω s , - k s vector) (or idler photon i(ω i , - k i vector)) is transformed in an idler photon i s (ω i , - k i vector) (or signal photon s i (ω s , - k s vector)), respectively. The proof of the reality of these phenomena is based on the optical phase conjugation property of the SPDC crystals. The high quality of the quantum mirrors is given by the distortion-undoing and amplification properties of these mirrors. Therefore, image of an object will be well observed only in coincidence measurements when the aperture, lens, and fiber tip are located according to the Gaussian thin-lens equation. In a similar way we obtain the interpretation of the results for the two photon entangled interference-diffraction patterns. These new results allow us to suggest that the quantum photography of objects, quantum holography, etc, can be now experimentally demonstrated. (authors)

Preparation of rock samples for measurement of the thermal neutron macroscopic absorption cross-section

International Nuclear Information System (INIS)

Czubek, J.A.; Burda, J.; Drozdowicz, K.; Igielski, A.; Kowalik, W.; Krynicka-Drozdowicz, E.; Woznicka, U.

1986-03-01

Preparation of rock samples for the measurement of the thermal neutron macroscopic absorption cross-section in small cylindrical two-region systems by a pulsed technique is presented. Requirements which should be fulfilled during the preparation of the samples due to physical assumptions of the method are given. A cylindrical vessel is filled with crushed rock and saturated with a medium strongly absorbing thermal neutrons. Water solutions of boric acid of well-known macroscopic absorption cross-section are used. Mass contributions of the components in the sample are specified. This is necessary for the calculation of the thermal neutron macroscopic absorption cross-section of the rock matrix. The conditions necessary for assuring the required accuracy of the measurement are given and the detailed procedure of preparation of the rock sample is described. (author)

Interference effects in angular and spectral distributions of X-ray Transition Radiation from Relativistic Heavy Ions crossing a radiator: Influence of absorption and slowing-down

Energy Technology Data Exchange (ETDEWEB)

Fiks, E.I.; Pivovarov, Yu.L.

2015-07-15

Theoretical analysis and representative calculations of angular and spectral distributions of X-ray Transition Radiation (XTR) by Relativistic Heavy Ions (RHI) crossing a radiator are presented taking into account both XTR absorption and RHI slowing-down. The calculations are performed for RHI energies of GSI, FAIR, CERN SPS and LHC and demonstrate the influence of XTR photon absorption as well as RHI slowing-down in a radiator on the appearance/disappearance of interference effects in both angular and spectral distributions of XTR.

One- and two-photon spectra of Nd3+ clusters in CaF2 and SrF2 crystals

International Nuclear Information System (INIS)

Basiev, Tasoltan T; Voronov, Valerii V; Glotova, M Yu; Papashvili, A G; Karasik, Aleksandr Ya

2003-01-01

The polarised two-photon (IR) and one-photon (visible) luminescence excitation spectra of Nd 3+ nanoclusters in CaF 2 and SrF 2 crystals are measured at 10 K using a F - 2 :LiF colour centre laser tunable in spectral ranges 1090 - 1230 nm and 545 - 615 nm with an emission linewidth of ∼0.02 - 0.03 cm -1 , an average output power of ∼55 mW, and a pulse repetition rate of 10 Hz. The two-photon excitation spectra at the 4 I 9/2 → 4 G 5/2 transition reveal the structure, which is absent upon one-photon excitation, which can be explained by different selection rules for some Stark - Stark transitions upon one- and two-photon absorption. (special issue devoted to the memory of academician a m prokhorov)

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Energy Technology Data Exchange (ETDEWEB)

Fountaine, Katherine T., E-mail: kfountai@caltech.edu [Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Whitney, William S. [Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Department of Physics, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Atwater, Harry A. [Joint Center for Artificial Photosynthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States); Department of Applied Physics and Materials Science, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States)

2014-10-21

We present a unified framework for resonant absorption in periodic arrays of high index semiconductor nanowires that combines a leaky waveguide theory perspective and that of photonic crystals supporting Bloch modes, as array density transitions from sparse to dense. Full dispersion relations are calculated for each mode at varying illumination angles using the eigenvalue equation for leaky waveguide modes of an infinite dielectric cylinder. The dispersion relations along with symmetry arguments explain the selectivity of mode excitation and spectral red-shifting of absorption for illumination parallel to the nanowire axis in comparison to perpendicular illumination. Analysis of photonic crystal band dispersion for varying array density illustrates that the modes responsible for resonant nanowire absorption emerge from the leaky waveguide modes.

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.

FENDL/E. Evaluated nuclear data library of neutron nuclear interaction cross-sections and photon production cross-sections and photon-atom interaction cross sections for fusion applications. Version 1.1 of November 1994

International Nuclear Information System (INIS)

Pashchenko, A.B.; Wienke, H.; Ganesan, S.; McLaughlin, P.K.

1996-01-01

This document presents the description of a physical tape containing the basic evaluated nuclear data library of neutron nuclear interaction cross-sections and photon production cross-sections and photon-atom interaction cross-sections for fusion applications. It is part of FENDL, the evaluated nuclear data library for fusion applications. The nuclear data are available cost-free for distribution to interested scientists upon request. The data can also be retrieved by the user via online access through international computer networks. (author). 11 refs, 1 tab

Two improved Monte Carlo photon cross section techniques

International Nuclear Information System (INIS)

Scudiere, M.B.

1978-01-01

Truncated series of Legendre coefficients and polynomials are often used in multigroup transport computer codes to describe group-to-group angular density transfer functions. Imposition of group structure on the energy continuum may create discontinuities in the first derivative of these functions. Because of the nature of these discontinuities efficient and accurate full-range polynomial expansions are not practically obtainable. Two separate and distinct methods for Monte Carlo photon transport are presented which eliminate essentially all major disadvantages of truncated expansions. In the first method, partial-range expansions are applied between the discontinuities. Here accurate low-order representations are obtained, which yield modest savings in computer charges. The second method employs unique properties of functions to replace them with a few smooth well-behaved representations. This method brings about a considerable savings in computer memory requirements. In addition, accuracy of the first method is maintained, while execution times are reduced even further

Random Photon Absorption Model Elucidates How Early Gain Control in Fly Photoreceptors Arises from Quantal Sampling

Science.gov (United States)

Song, Zhuoyi; Zhou, Yu; Juusola, Mikko

2016-01-01

Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantum-gain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantum-gain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multi-photon-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to light-adaptation is marginal (≤ 1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light. PMID:27445779

Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at

Science.gov (United States)

Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Krätschmer, I.; Liko, D.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Luyckx, S.; Ochesanu, S.; Roland, B.; Rougny, R.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Heracleous, N.; Kalogeropoulos, A.; Keaveney, J.; Kim, T. J.; Lowette, S.; Maes, M.; Olbrechts, A.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Favart, L.; Gay, A. P. R.; Léonard, A.; Marage, P. E.; Mohammadi, A.; Perniè, L.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Benucci, L.; Cimmino, A.; Costantini, S.; Crucy, S.; Dildick, S.; Garcia, G.; Klein, B.; Lellouch, J.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Salva Diblen, S.; Sigamani, M.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; Da Silveira, G. G.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jez, P.; Komm, M.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins Junior, M.; Dos Reis Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Malbouisson, H.; Malek, M.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santaolalla, J.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Du, R.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Plestina, R.; Tao, J.; Wang, X.; Wang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, Y.; Li, Q.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Zhang, L.; Zou, W.; Avila, C.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Mekterovic, D.; Morovic, S.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Mahmoud, M. A.; Mahrous, A.; Radi, A.; Kadastik, M.; Müntel, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Nayak, A.; Rander, J.; Rosowsky, A.; Titov, M.; Baffioni, S.; Beaudette, F.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Mastrolorenzo, L.; Miné, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Veelken, C.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Juillot, P.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Beaupere, N.; Boudoul, G.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Ruiz Alvarez, J. D.; Sgandurra, L.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Xiao, H.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Bontenackels, M.; Calpas, B.; Edelhoff, M.; Feld, L.; Hindrichs, O.; Klein, K.; Ostapchuk, A.; Perieanu, A.; Raupach, F.; Sammet, J.; Schael, S.; Sprenger, D.; Weber, H.; Wittmer, B.; Zhukov, V.; Ata, M.; Caudron, J.; Dietz-Laursonn, E.; Duchardt, D.; Erdmann, M.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Klingebiel, D.; Knutzen, S.; Kreuzer, P.; Merschmeyer, M.; Meyer, A.; Olschewski, M.; Padeken, K.; Papacz, P.; Reithler, H.; Schmitz, S. A.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Weber, M.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Geenen, H.; Geisler, M.; Haj Ahmad, W.; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Lingemann, J.; Nowack, A.; Nugent, I. M.; Perchalla, L.; Pooth, O.; Stahl, A.; Asin, I.; Bartosik, N.; Behr, J.; Behrenhoff, W.; Behrens, U.; Bell, A. J.; Bergholz, M.; Bethani, A.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Geiser, A.; Grebenyuk, A.; Gunnellini, P.; Habib, S.; Hauk, J.; Hellwig, G.; Hempel, M.; Horton, D.; Jung, H.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Krämer, M.; Krücker, D.; Lange, W.; Leonard, J.; Lipka, K.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Novgorodova, O.; Nowak, F.; Ntomari, E.; Perrey, H.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Riedl, C.; Ron, E.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Saxena, P.; Schmidt, R.; Schoerner-Sadenius, T.; Schröder, M.; Stein, M.; Vargas Trevino, A. D. R.; Walsh, R.; Wissing, C.; Aldaya Martin, M.; Blobel, V.; Enderle, H.; Erfle, J.; Garutti, E.; Goebel, K.; Görner, M.; Gosselink, M.; Haller, J.; Höing, R. S.; Kirschenmann, H.; Klanner, R.; Kogler, R.; Lange, J.; Lapsien, T.; Lenz, T.; Marchesini, I.; Ott, J.; Peiffer, T.; Pietsch, N.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Seidel, M.; Sibille, J.; Sola, V.; Stadie, H.; Steinbrück, G.; Troendle, D.; Usai, E.; Vanelderen, L.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; De Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Guthoff, M.; Hartmann, F.; Hauth, T.; Held, H.; Hoffmann, K. H.; Husemann, U.; Katkov, I.; Kornmayer, A.; Kuznetsova, E.; Lobelle Pardo, P.; Martschei, D.; Mozer, M. U.; Müller, Th.; Niegel, M.; Nürnberg, A.; Oberst, O.; Quast, G.; Rabbertz, K.; Ratnikov, F.; Röcker, S.; Schilling, F.-P.; Schott, G.; Simonis, H. J.; Stober, F. M.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Wolf, R.; Zeise, M.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Kesisoglou, S.; Kyriakis, A.; Loukas, D.; Markou, A.; Markou, C.; Psallidas, A.; Topsis-Giotis, I.; Gouskos, L.; Panagiotou, A.; Saoulidou, N.; Stiliaris, E.; Aslanoglou, X.; Evangelou, I.; Flouris, G.; Foudas, C.; Jones, J.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Karancsi, J.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Swain, S. K.; Beri, S. B.; Bhatnagar, V.; Dhingra, N.; Gupta, R.; Kaur, M.; Mittal, M.; Nishu, N.; Sharma, A.; Singh, J. B.; Kumar, Ashok; Kumar, Arun; Ahuja, S.; Bhardwaj, A.; Choudhary, B. C.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, V.; Shivpuri, R. K.; Banerjee, S.; Bhattacharya, S.; Chatterjee, K.; Dutta, S.; Gomber, B.; Jain, Sa.; Jain, Sh.; Khurana, R.; Modak, A.; Mukherjee, S.; Roy, D.; Sarkar, S.; Sharan, M.; Singh, A. P.; Abdulsalam, A.; Dutta, D.; Kailas, S.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Banerjee, S.; Chatterjee, R. M.; Dugad, S.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Kole, G.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Mohanty, G. B.; Parida, B.; Sudhakar, K.; Wickramage, N.; Banerjee, S.; Dugad, S.; Arfaei, H.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Jafari, A.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Safarzadeh, B.; Zeinali, M.; Grunewald, M.; Abbrescia, M.; Barbone, L.; Calabria, C.; Chhibra, S. S.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Marangelli, B.; My, S.; Nuzzo, S.; Pacifico, N.; Pompili, A.; Pugliese, G.; Radogna, R.; Selvaggi, G.; Silvestris, L.; Singh, G.; Venditti, R.; Verwilligen, P.; Zito, G.; Abbiendi, G.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Meneghelli, M.; Montanari, A.; Navarria, F. L.; Odorici, F.; Perrotta, A.; Primavera, F.; Rossi, A. M.; Rovelli, T.; Siroli, G. 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M.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Azzi, P.; Bellato, M.; Biasotto, M.; Bisello, D.; Branca, A.; Checchia, P.; Dorigo, T.; Dosselli, U.; Fanzago, F.; Galanti, M.; Gasparini, F.; Gasparini, U.; Giubilato, P.; Gonella, F.; Gozzelino, A.; Kanishchev, K.; Lacaprara, S.; Lazzizzera, I.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Gabusi, M.; Ratti, S. P.; Riccardi, C.; Salvini, P.; Vitulo, P.; Biasini, M.; Bilei, G. M.; Fanò, L.; Lariccia, P.; Mantovani, G.; Menichelli, M.; Romeo, F.; Saha, A.; Santocchia, A.; Spiezia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Broccolo, G.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fiori, F.; Foà, L.; Giassi, A.; Grippo, M. T.; Kraan, A.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Moon, C. S.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Serban, A. 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D.; Park, H.; Sakharov, A.; Son, D. C.; Kim, J. Y.; Kim, Zero J.; Song, S.; Choi, S.; Gyun, D.; Hong, B.; Jo, M.; Kim, H.; Kim, Y.; Lee, B.; Lee, K. S.; Park, S. K.; Roh, Y.; Choi, M.; Kim, J. H.; Park, C.; Park, I. C.; Park, S.; Ryu, G.; Choi, Y.; Choi, Y. K.; Goh, J.; Kwon, E.; Lee, J.; Seo, H.; Yu, I.; Juodagalvis, A.; Komaragiri, J. R.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-de La Cruz, I.; Lopez-Fernandez, R.; Martínez-Ortega, J.; Sanchez-Hernandez, A.; Villasenor-Cendejas, L. M.; Carrillo Moreno, S.; Vazquez Valencia, F.; Salazar Ibarguen, H. A.; Casimiro Linares, E.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Doesburg, R.; Reucroft, S.; Ahmad, A.; Ahmad, M.; Asghar, M. I.; Butt, J.; Hassan, Q.; Hoorani, H. R.; Khan, W. A.; Khurshid, T.; Qazi, S.; Shah, M. 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V.; Vinogradov, A.; Belyaev, A.; Boos, E.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Khein, L.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Dordevic, M.; Ekmedzic, M.; Milosevic, J.; Aguilar-Benitez, M.; Alcaraz Maestre, J.; Battilana, C.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Domínguez Vázquez, D.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Ferrando, A.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Merino, G.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Willmott, C.; Albajar, C.; de Trocóniz, J. 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M.; Rogerson, S.; Rose, A.; Seez, C.; Sharp, P.; Sparrow, A.; Tapper, A.; Vazquez Acosta, M.; Virdee, T.; Wakefield, S.; Wardle, N.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leggat, D.; Leslie, D.; Martin, W.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Dittmann, J.; Hatakeyama, K.; Kasmi, A.; Liu, H.; Scarborough, T.; Charaf, O.; Cooper, S. I.; Henderson, C.; Rumerio, P.; Avetisyan, A.; Bose, T.; Fantasia, C.; Heister, A.; Lawson, P.; Lazic, D.; Richardson, C.; Rohlf, J.; Sperka, D.; St. John, J.; Sulak, L.; Alimena, J.; Bhattacharya, S.; Christopher, G.; Cutts, D.; Demiragli, Z.; Ferapontov, A.; Garabedian, A.; Heintz, U.; Jabeen, S.; Kukartsev, G.; Laird, E.; Landsberg, G.; Luk, M.; Narain, M.; Segala, M.; Sinthuprasith, T.; Speer, T.; Swanson, J.; Breedon, R.; Breto, G.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. 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F.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Baarmand, M. M.; Dorney, B.; Hohlmann, M.; Kalakhety, H.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Bazterra, V. E.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Khalatyan, S.; Kurt, P.; Moon, D. H.; O'Brien, C.; Silkworth, C.; Turner, P.; Varelas, N.; Akgun, U.; Albayrak, E. A.; Bilki, B.; Clarida, W.; Dilsiz, K.; Duru, F.; Haytmyradov, M.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Rahmat, R.; Sen, S.; Tan, P.; Tiras, E.; Wetzel, J.; Yetkin, T.; Yi, K.; Barnett, B. A.; Blumenfeld, B.; Bolognesi, S.; Fehling, D.; Gritsan, A. V.; Maksimovic, P.; Martin, C.; Swartz, M.; Baringer, P.; Bean, A.; Benelli, G.; Gray, J.; Kenny, R. P.; Murray, M.; Noonan, D.; Sanders, S.; Sekaric, J.; Stringer, R.; Wang, Q.; Wood, J. S.; Barfuss, A. F.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Shrestha, S.; Svintradze, I.; Gronberg, J.; Lange, D.; Rebassoo, F.; Wright, D.; Baden, A.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kolberg, T.; Lu, Y.; Marionneau, M.; Mignerey, A. C.; Pedro, K.; Skuja, A.; Temple, J.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Bauer, G.; Busza, W.; Cali, I. A.; Chan, M.; Di Matteo, L.; Dutta, V.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Klute, M.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Ma, T.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Stöckli, F.; Sumorok, K.; Velicanu, D.; Veverka, J.; Wyslouch, B.; Yang, M.; Yoon, A. S.; Zanetti, M.; Zhukova, V.; Dahmes, B.; De Benedetti, A.; Gude, A.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rusack, R.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Cremaldi, L. M.; Kroeger, R.; Oliveros, S.; Perera, L.; Sanders, D. A.; Summers, D.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Gonzalez Suarez, R.; Keller, J.; Knowlton, D.; Kravchenko, I.; Lazo-Flores, J.; Malik, S.; Meier, F.; Snow, G. R.; Dolen, J.; Godshalk, A.; Iashvili, I.; Jain, S.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Haley, J.; Massironi, A.; Nash, D.; Orimoto, T.; Trocino, D.; Wood, D.; Zhang, J.; Anastassov, A.; Hahn, K. A.; Kubik, A.; Lusito, L.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Velasco, M.; Won, S.; Berry, D.; Brinkerhoff, A.; Chan, K. M.; Drozdetskiy, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Kolb, J.; Lannon, K.; Luo, W.; Lynch, S.; Marinelli, N.; Morse, D. M.; Pearson, T.; Planer, M.; Ruchti, R.; Slaunwhite, J.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hill, C.; Hughes, R.; Kotov, K.; Ling, T. Y.; Puigh, D.; Rodenburg, M.; Smith, G.; Vuosalo, C.; Winer, B. L.; Wolfe, H.; Wulsin, H. W.; Berry, E.; Elmer, P.; Halyo, V.; Hebda, P.; Hunt, A.; Jindal, P.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Piroué, P.; Quan, X.; Raval, A.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zenz, S. C.; Zuranski, A.; Brownson, E.; Lopez, A.; Mendez, H.; Ramirez Vargas, J. E.; Alagoz, E.; Benedetti, D.; Bolla, G.; Bortoletto, D.; De Mattia, M.; Everett, A.; Hu, Z.; Jha, M. K.; Jones, M.; Jung, K.; Kress, M.; Leonardo, N.; Lopes Pegna, D.; Maroussov, V.; Merkel, P.; Miller, D. H.; Neumeister, N.; Radburn-Smith, B. C.; Shipsey, I.; Silvers, D.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Yoo, H. D.; Zablocki, J.; Zheng, Y.; Parashar, N.; Adair, A.; Akgun, B.; Ecklund, K. M.; Geurts, F. J. M.; Li, W.; Michlin, B.; Padley, B. P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Miner, D. C.; Petrillo, G.; Vishnevskiy, D.; Zielinski, M.; Bhatti, A.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Lungu, G.; Malik, S.; Mesropian, C.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Rekovic, V.; Robles, J.; Salur, S.; Schnetzer, S.; Seitz, C.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Rose, K.; Spanier, S.; Yang, Z. C.; York, A.; Bouhali, O.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Krutelyov, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Safonov, A.; Sakuma, T.; Suarez, I.; Tatarinov, A.; Toback, D.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kovitanggoon, K.; Kunori, S.; Lee, S. W.; Libeiro, T.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sharma, M.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Lin, C.; Neu, C.; Wood, J.; Gollapinni, S.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Belknap, D. A.; Borrello, L.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Duric, S.; Friis, E.; Grothe, M.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Klukas, J.; Lanaro, A.; Lazaridis, C.; Levine, A.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Sarangi, T.; Savin, A.; Smith, W. H.; Woods, N.

2014-11-01

A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at is presented. The data sample corresponds to an integrated luminosity of 5.0 collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 respectively, in the pseudorapidity range , and with an angular separation , is . Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.

Two-photon excitation with pico-second fluorescence lifetime imaging to detect nuclear association of flavanols

Energy Technology Data Exchange (ETDEWEB)

Mueller-Harvey, Irene, E-mail: i.mueller-harvey@reading.ac.uk [Chemistry and Biochemistry Laboratory, Food Production and Quality Research Division, School of Agriculture, Policy and Development, University of Reading, P O Box 236, Reading RG6 6AT (United Kingdom); Feucht, Walter, E-mail: walter.feucht@gmail.com [Department of Plant Sciences, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Polster, Juergen, E-mail: j.polster@wzw.tum.de [Department of Physical Biochemistry, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Trnkova, Lucie, E-mail: lucie.trnkova@uhk.cz [University of Hradec Kralove, Faculty of Science, Department of Chemistry, Rokitanskeho 62, 50003 Hradec Kralove (Czech Republic); Burgos, Pierre, E-mail: pierre.burgos@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Parker, Anthony W., E-mail: tony.parker@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Botchway, Stanley W., E-mail: stan.botchway@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

2012-03-16

Highlights: Black-Right-Pointing-Pointer This fluorescence lifetime imaging microscopy (FLIM) technique for flavanols overcomes autofluorescence interference in cells. Black-Right-Pointing-Pointer Plant flavanols differed in their lifetimes. Black-Right-Pointing-Pointer Dissolved and bound flavanols revealed contrasting lifetime changes. Black-Right-Pointing-Pointer This technique will allow studying of flavanol trafficking in live cells. - Abstract: Two-photon excitation enabled for the first time the observation and measurement of excited state fluorescence lifetimes from three flavanols in solution, which were {approx}1.0 ns for catechin and epicatechin, but <45 ps for epigallocatechin gallate (EGCG). The shorter lifetime for EGCG is in line with a lower fluorescence quantum yield of 0.003 compared to catechin (0.015) and epicatechin (0.018). In vivo experiments with onion cells demonstrated that tryptophan and quercetin, which tend to be major contributors of background fluorescence in plant cells, have sufficiently low cross sections for two-photon excitation at 630 nm and therefore do not interfere with detection of externally added or endogenous flavanols in Allium cepa or Taxus baccata cells. Applying two-photon excitation to flavanols enabled 3-D fluorescence lifetime imaging microscopy and showed that added EGCG penetrated the whole nucleus of onion cells. Interestingly, EGCG and catechin showed different lifetime behaviour when bound to the nucleus: EGCG lifetime increased from <45 to 200 ps, whilst catechin lifetime decreased from 1.0 ns to 500 ps. Semi-quantitative measurements revealed that the relative ratios of EGCG concentrations in nucleoli associated vesicles: nucleus: cytoplasm were ca. 100:10:1. Solution experiments with catechin, epicatechin and histone proteins provided preliminary evidence, via the appearance of a second lifetime ({tau}{sub 2} = 1.9-3.1 ns), that both flavanols may be interacting with histone proteins. We conclude that there

Secured Optical Communications Using Quantum Entangled Two-Photon Transparency Modulation

Science.gov (United States)

Kojima, Jun (Inventor); Nguyen, Quang-Viet (Inventor); Lekki, John (Inventor)

2015-01-01

A system and method is disclosed wherein optical signals are coded in a transmitter by tuning or modulating the interbeam delay time (which modulates the fourth-order coherence) between pairs of entangled photons. The photon pairs are either absorbed or not absorbed (transparent) by an atomic or molecular fluorescer in a receiver, depending on the inter-beam delay that is introduced in the entangled photon pairs. Upon the absorption, corresponding fluorescent optical emissions follow at a certain wavelength, which are then detected by a photon detector. The advantage of the disclosed system is that it eliminates a need of a coincidence counter to realize the entanglement-based secure optical communications because the absorber acts as a coincidence counter for entangled photon pairs.

Design and synthesis of hyperstructured molecules based on cyclophosphazene core for multiphoton absorption

International Nuclear Information System (INIS)

Naik, K. Praveen Kumar; Sreeramulu, V.; Ramya, E.; Muralidharan, K.; Rao, D. Narayana

2016-01-01

Cyclophosphazene based hyperstructured molecules were synthesized through simple nucleophilic substitution reactions. All these molecules were characterized by multinuclear NMR, MALDI and HRMS spectral data. Third order nonlinear optical properties of the hyperstructured molecules were measured using Z-scan technique with 532 nm, picosecond (ps) laser and 800 nm, femtosecond (fs) laser pulses. The molecules showed reverse saturable absorption on excitation at both 532 nm and 800 nm, which could be attributed to the two-photon absorption (2 PA) and three-photon absorption (3 PA), respectively. The 2 PA and 3 PA cross section values exhibited by the molecules based on cyclophosphazene are as high as 527 GM and 1.86 × 10"−"7"6 cm"−"6 s"2 photon"−"1, respectively. The 2PA, 3PA coefficients and optical limiting properties make them suitable candidates for nonlinear optical devices in the visible and near IR range. - Graphical abstract: The hyperstructured molecules based on cyclophosphazene core were synthesized and used for multiphoton absorption. Open aperture Z-scan curves of hyper structured molecules at the excitation of (a) picosecond laser and (b) femtosecond laser representing multiphoton absorption properties are reported. - Highlights: • Two hyperstructured molecules based on cyclophosphazene core are designed for multiphoton absorption. • NLO properties are measured using Z-scan technique at 532 nm and 800 nm wavelengths. • The molecules were tested for the optical limiting applications at 532 nm and 800 nm laser pulses.

Design and synthesis of hyperstructured molecules based on cyclophosphazene core for multiphoton absorption

Energy Technology Data Exchange (ETDEWEB)

Naik, K. Praveen Kumar [School of Chemistry, University of Hyderabad, Hyderabad 500046 India (India); Sreeramulu, V. [School of Physics, University of Hyderabad, Hyderabad 500046 India (India); CNR-IFN CSMFO Laboratory, Via alla Cascata, 56/C Povo, Trento (Italy); Ramya, E. [School of Physics, University of Hyderabad, Hyderabad 500046 India (India); Muralidharan, K., E-mail: murali@uohyd.ac.in [School of Chemistry, University of Hyderabad, Hyderabad 500046 India (India); Rao, D. Narayana [School of Physics, University of Hyderabad, Hyderabad 500046 India (India)

2016-09-01

Cyclophosphazene based hyperstructured molecules were synthesized through simple nucleophilic substitution reactions. All these molecules were characterized by multinuclear NMR, MALDI and HRMS spectral data. Third order nonlinear optical properties of the hyperstructured molecules were measured using Z-scan technique with 532 nm, picosecond (ps) laser and 800 nm, femtosecond (fs) laser pulses. The molecules showed reverse saturable absorption on excitation at both 532 nm and 800 nm, which could be attributed to the two-photon absorption (2 PA) and three-photon absorption (3 PA), respectively. The 2 PA and 3 PA cross section values exhibited by the molecules based on cyclophosphazene are as high as 527 GM and 1.86 × 10{sup −76} cm{sup −6} s{sup 2} photon{sup −1}, respectively. The 2PA, 3PA coefficients and optical limiting properties make them suitable candidates for nonlinear optical devices in the visible and near IR range. - Graphical abstract: The hyperstructured molecules based on cyclophosphazene core were synthesized and used for multiphoton absorption. Open aperture Z-scan curves of hyper structured molecules at the excitation of (a) picosecond laser and (b) femtosecond laser representing multiphoton absorption properties are reported. - Highlights: • Two hyperstructured molecules based on cyclophosphazene core are designed for multiphoton absorption. • NLO properties are measured using Z-scan technique at 532 nm and 800 nm wavelengths. • The molecules were tested for the optical limiting applications at 532 nm and 800 nm laser pulses.

Two-photon laser-induced fluorescence studies of HS radicals, DS radicals, and I atoms

Energy Technology Data Exchange (ETDEWEB)

Tiee, J J; Ferris, M J; Loge, G W; Wampler, F B

1983-04-15

A two-photon laser-induced excitation and fluorescence technique has been used to study the A /sup 2/..sigma../sup +/ - X/sup 2/PI transition of HS and DS radicals and various high-lying /sup 4/P/sup 0/, /sup 2/D/sup 0/, and /sup 4/D/sup 0/ states of the I atom. The two-photon excitation cross sections and detection sensitivity are discussed. 13 references, 5 figures.

Temperature-dependent absorption cross sections for hydrogen peroxide vapor

Science.gov (United States)

Nicovich, J. M.; Wine, P. H.

1988-01-01

Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

Selective two-photon collagen crosslinking in situ measured by Brillouin microscopy (Conference Presentation)

Science.gov (United States)

Kwok, Sheldon J. J.; Kuznetsov, Ivan A.; Kim, Moonseok; Choi, Myunghwan; Scarcelli, Giuliano; Yun, Seok-Hyun

2017-02-01

Two-photon polymerization and crosslinking are commonly used methods for microfabrication of three-dimensional structures with applications spanning from photonic microdevices, drug delivery systems, to cellular scaffolds. However, the use of two-photon processes for precise, internal modification of biological tissues has not yet been reported. One of the major challenges has been a lack of appropriate tools to monitor and characterize crosslinked regions nondestructively. Here, we demonstrate spatially selective two-photon collagen crosslinking (2P-CXL) in intact tissue for the first time. Using riboflavin photosensitizer and femtosecond laser irradiation, we crosslinked a small volume of tissue within animal corneas. Collagen fiber orientations and photobleaching were characterized by second harmonic generation and two-photon fluorescence imaging, respectively. Using confocal Brillouin microscopy, we measured local changes in longitudinal mechanical moduli and visualized the cross-linked pattern without perturbing surrounding non-irradiated regions. 2P-CXL-induced tissue stiffening was comparable to that achieved with conventional one-photon CXL. Our results demonstrate the ability to selectively stiffen biological tissue in situ at high spatial resolution, with broad implications in ophthalmology, laser surgery, and tissue engineering.

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...

Deep and tapered silicon photonic crystals for achieving anti-reflection and enhanced absorption.

Science.gov (United States)

Hung, Yung-Jr; Lee, San-Liang; Coldren, Larry A

2010-03-29

Tapered silicon photonic crystals (PhCs) with smooth sidewalls are realized using a novel single-step deep reactive ion etching. The PhCs can significantly reduce the surface reflection over the wavelength range between the ultra-violet and near-infrared regions. From the measurements using a spectrophotometer and an angle-variable spectroscopic ellipsometer, the sub-wavelength periodic structure can provide a broad and angular-independent antireflective window in the visible region for the TE-polarized light. The PhCs with tapered rods can further reduce the reflection due to a gradually changed effective index. On the other hand, strong optical resonances for TM-mode can be found in this structure, which is mainly due to the existence of full photonic bandgaps inside the material. Such resonance can enhance the optical absorption inside the silicon PhCs due to its increased optical paths. With the help of both antireflective and absorption-enhanced characteristics in this structure, the PhCs can be used for various applications.

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...

Sensitive measurement of nonlinear absorption and optical limiting in undoped and Fe-doped ZnO quantum dots using pulsed laser

Science.gov (United States)

Sharma, D.; Malik, B. P.; Gaur, A.

2016-11-01

Zinc oxide quantum dots (QDs) with Fe-doping at different concentrations were prepared by chemical co-precipitation method. The prepared QDs were characterized by UV-Vis spectroscopy, X-ray diffraction and Z-scan technique. The sizes of QDs were found to be within 4.6-6.6 nm range. The nonlinear parameters viz. two-photon absorption coefficient (βTPA) and two-photon absorption cross-section (σTPA) were extracted with the help of open aperture Z-scan technique using nanosecond Nd:YAG laser operating at wavelength 532 nm. Higher values of βTPA and σTPA for Fe doped ZnO implied that they were potential materials for development of photonics devices and sensor protection applications. Fe doped sample (3 % by wt) was found to be the best optical limiter with limiting threshold intensity of 0.64 TW/cm2.

Mass attenuation and mass energy absorption coefficients for 10 keV to 10 MeV photons; Coefficients d'attenuation massique et d'absorption massique en energie pour les photons de 10 keV a 10 MeV

Energy Technology Data Exchange (ETDEWEB)

Joffre, H; Pages, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

In this report are given the elements allowing the definition of the values of mass attenuation coefficients and mass energy absorption coefficients for some elements and mixtures, necessary for the study of tissue equivalent materials, for photons in the energy range 10 keV to 10 MeV. After a short reminding of the definitions of the two coefficients, follows, in table form, a compilation of these coefficients, as a function of energy, for simple elements, for certain mineral compounds, organic compounds, gases and particularly of soft tissues. (author) [French] Dans ce rapport, sont donnes les elements permettant de determiner les valeurs des coefficients d'attenuation massique et d'absorption massique en energie pour certains elements et melanges necessaires a l'etude des materiaux equivalents aux tissus pour les photons dans le domaine d'energie allant de 10 keV a 10 MeV. Apres un bref rappel des definitions des deux coefficients, suit, sous forme de tableaux, un recueil de ces coefficients, en fonction de l'energie, pour les elements simples, certains composes mineraux, composes organiques, gaz, et, particulierement, pour les tissus mous. (auteur)

Extreme nonlinearities in InAs/InP nanowire gain media: the two-photon induced laser

DEFF Research Database (Denmark)

Capua, Amir; Kami, Ouri; Eisenstein, Gadi

2012-01-01

We demonstrate a novel laser oscillation scheme in an InAs / InP wire-like quantum dash gain medium. A short optical pulse excites carriers by two photon absorption which relax to the energy levels providing gain thereby enabling laser oscillations. The nonlinear dynamic interaction is analyzed a...

A review of two photon physics

International Nuclear Information System (INIS)

Cooper, S.

1982-08-01

This talk is intended as an introduction for those not yet expert in two-photon physics, especially those e + e - one-photon physicists who still think of two-photon events as background. I concentrate on the physics questions involved, especially emphasizing the areas where I feel progress can be made in the near future, and of necessity leaving most experimental details to be found in the references. After a quick survey of the field and a few words about kinematics, I discuss in detail two major fields: the photon structure function and resonance production. (orig.)

FENDL/E-2.0. Evaluated nuclear data library of neutron-nucleus interaction cross sections and photon production cross sections and photon-atom interaction cross sections for fusion applications. Version 1, March 1997. Summary documentation

International Nuclear Information System (INIS)

Pashchenko, A.B.; Wienke, H.

1998-01-01

This document presents the description of a physical tape containing the basic evaluated nuclear data library of neutron-nucleus interaction cross sections, photon production cross sections and photon-atom interaction cross sections for fusion applications. It is part of the evaluated nuclear data library for fusion applications FENDL-2. The data are available cost-free from the Nuclear Data Section upon request. The data can also be retrieved by the user via online access through international computer networks. (author)

MCNP: a general Monte Carlo code for neutron and photon transport

International Nuclear Information System (INIS)

1978-07-01

The general-purpose Monte Carlo code MCNP can be used for neutron, photon, or coupled neutron--photon transport. The code treats an arbitrary three-dimensional configuration of materials in geometric cells bounded by first- and second-degree surfaces and some special fourth-degree surfaces (elliptical tori). Pointwise cross-section data are used. For neutrons, all reactions given in a particular cross-section evaluation (such as ENDF/B-IV) are accounted for. For photons, the code takes account of incoherent and coherent scattering, the possibility of fluorescent emission following photoelectric absorption, and absorption in pair production with local emission of annihilation radiation. Standard optional variance reduction schemes include geometry splitting and Russian roulette, the exponential transformation, energy splitting, forced collisions in designated cells, flux estimates at point detectors, track-length estimators, and source biasing. The standard output of MCNP includes two-way current as a function of energy, time, and angle with the normal, across any subset of bounding surfaces in the problem. Fluxes across any set of bounding surfaces are available as a function of time and energy. Similarly, the flux at designated points and the average flux in a cell (track length per unit volume) are standard tallies. Reactions such as fissions or absorptions may be obtained in a subset of geometric cells. The heating tallies give the energy deposition per starting particle. In addition, particles may be flagged when they cross specified surfaces or enter designated cells, and the contributions of these flagged particles to certain of the tallies are listed separately. All quantities printed out have their relative errors listed also. 11 figures, 27 tables

Quantum entanglement and phase transition in a two-dimensional photon-photon pair model

International Nuclear Information System (INIS)

Zhang Jianjun; Yuan Jianhui; Zhang Junpei; Cheng Ze

2013-01-01

We propose a two-dimensional model consisting of photons and photon pairs. In the model, the mixed gas of photons and photon pairs is formally equivalent to a two-dimensional system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phases. Using the variational method, we discuss the quantum phase transition of the mixed gas and obtain the critical coupling line analytically. Moreover, we also find that the phase transition of the photon gas can be interpreted as enhanced second harmonic generation. We then discuss the entanglement between photons and photon pairs. Additionally, we also illustrate how the entanglement between photons and photon pairs can be associated with the phase transition of the system.

Measurement of the Hadronic Cross-Section for the Scattering of Two Virtual Photons at LEP

CERN Document Server

Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Bethke, S.; Biebel, O.; Bloodworth, I.J.; Boeriu, O.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Cammin, J.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Couchman, J.; Csilling, A.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; De Roeck, A.; De Wolf, E.A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Glenzinski, D.; Goldberg, J.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hauschildt, J.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Homer, R.J.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Ishii, K.; Jawahery, A.; Jeremie, H.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Komamiya, S.; Kowalewski, Robert V.; Kramer, T.; Kress, T.; Krieger, P.; von Krogh, J.; Krop, D.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lawson, I.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Littlewood, C.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Martinez, G.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Rick, H.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rozen, Y.; Runge, K.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sarkisyan, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Spano, F.; Sproston, M.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Stumpf, L.; Surrow, B.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomas, J.; Thomson, M.A.; Torrence, E.; Toya, D.; Trefzger, T.; Tricoli, A.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vachon, B.; Vollmer, C.F.; Vannerem, P.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.

2001-01-01

The interaction of virtual photons is investigated using the reaction e+e- -> e+e- hadrons based on data taken by the OPAL experiment at e+e- centre-of-mass energies sqrt(s_ee)=189-209 GeV, for W>5 GeV and at an average Q^2 of 17.9 GeV^2. The measured cross-sections are compared to predictions of the Quark Parton Model (QPM), to the Leading Order QCD Monte Carlo model PHOJET to the NLO prediction for the reaction e+e- -> e+e-qqbar, and to BFKL calculations. PHOJET, NLO e+e- -> e+e-qqbar, and QPM describe the data reasonably well, whereas the cross-section predicted by a Leading Order BFKL calculation is too large.

Two-photon superradiance in extended medium

International Nuclear Information System (INIS)

Branzan, V.; Enache, N.

1993-01-01

The possibility of collectivization of an ensemble of atoms of an extended system (the distance between atoms is larger or equal to the wave-length of a spontaneous emitted radiation) during two-photon spontaneous decay is theoretically investigated. It is demonstrated that such systems of inverted atoms should emit phase-correlated pairs of photons. The time-space correlation among atoms is realized due to the two-photon exchanging through the electromagnetic field's vacuum. An increase of the spontaneous decay rate of the two-atom inverted ensemble is demonstrated. The dependence of two-photon superradiance on the sample geometry is investigated. A non-equilibrium method of the elimination of the atoms level Fermi-operators is proposed. (Author)

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 G_Ep/G_Mp, 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.

Test of virtual photon theory. [Cross sections, square-well potential, 0 to 300 MeV

Energy Technology Data Exchange (ETDEWEB)

Dressler, E T; Tomusiak, E L [Saskatchewan Univ., Saskatoon (Canada). Saskatchewan Accelerator Lab.

1976-11-30

In order to extract a photodisintegration cross section in the c.m. system from an electrodisintegration cross section measured in the lab system, one has to assume that the electrons are mostly scattered forward and that the monopole contributions are negligible. To test the validity of these approximations, a square well potential was assumed for the initial and final states and the photodisintegration cross section was calculated exactly within this model. These results were then compared with the results one would obtain using the virtual photon theory approximations for electron energies of 0-300 MeV and excitation energies up to 40 MeV. In comparing the two results, it is shown how and why the virtual photon theory approximations fail in certain kinematical regions.

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

Enhanced two-photon emission from a dressed biexciton

International Nuclear Information System (INIS)

Sánchez Muñoz, Carlos; Laussy, Fabrice P; Tejedor, Carlos; Valle, Elena del

2015-01-01

Radiative two-photon cascades from biexcitons in semiconductor quantum dots under resonant two-photon excitation are promising candidates for the generation of photon pairs. In this work, we propose a scheme to obtain two-photon emission that allows us to operate under very intense driving fields. This approach relies on the Purcell enhancement of two-photon virtual transitions between states of the biexciton dressed by the laser. The richness provided by the biexcitonic level structure allows to reach a variety of regimes, from antibunched and bunched photon pairs with polarization orthogonal to the driving field, to polarization entangled two-photon emission. This provides evidence that the general paradigm of two-photon emission from a ladder of dressed states can find interesting, particular implementations in a variety of systems. (paper)

DWBA differential and total pair production cross sections for intermediate energy photons

International Nuclear Information System (INIS)

Selvaraju, C.; Bhullar, A.S.; Sud, K.K.

2001-01-01

We present in this communication the theoretical differential and total cross section for electron-positron pair creation by intermediate energy photons (5.0-10.0 MeV) on different targets (Z=1, 30, 50, 68, 82 and 92). The computed cross sections are in distorted wave Born approximation (DWBA) in point Coulomb potential. The database of the differential and total pair production cross sections is presented in tabulated as well as in graphical form and the interpolation of differential cross sections for different atomic numbers, positron and photon energies is discussed

The investigation of the elastic photon scattering cross sections by copper atoms and ions

International Nuclear Information System (INIS)

Kuplyauskene, A.B.

1976-01-01

The differential cross sections of coherent scattering of photons on a copper atom and ions Cu + and Cu 2+ and also on ions Zn + and Ga 2+ in their ground states have been studied theoretically. The energy of an incident photon has varied in the range from 0.5 keV to 200 keV, and the scattering cross sections are given for angles of 30 deg, 60 deg, 90 deg, 120 deg, 150 deg. The calculations are performed in the formfactor approximation with the use of generalized hydrogen-like analytical radial orbitals. To clarify the contribution from individual shells the cross sections of photon scattering on individual electron of shells are calculated. It follows from the calculations that when the energies of the incident photon are less than 4 keV, the main contribution into the differential cross section is made by external electrons. Then, alongside with the increase of the energy, the contribution of the electrons decreases, and the inner shells begin to play a more important role. Therefore the photon cross sections for the energies greater than 50 keV practically coincide for atoms and ions of copper. The general regularities of the cross section variation accompanying the increase of the photon energy are similar for all the elements under study. The angular dependences of cross sections are such that they decrease first and after reaching the minimum at angles of 90 deg - 120 deg increase again

Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV

International Nuclear Information System (INIS)

Manohara, S.R.; Hanagodimath, S.M.

2007-01-01

Effective atomic numbers for photon energy-absorption (Z PEAeff ) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1 keV to 20 MeV. The Z PEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective atomic number for photon interaction (Z PIeff ) and Z PEAeff with energy are shown graphically. Significant differences exist between Z PIeff and the Z PEAeff in the energy region of 8-100 keV for histidine and threonine; 6-100 keV for leucine, lysine, tryptophan, phenylalanine and valine; 15-400 keV for methionine. The effect of absorption edge on effective atomic numbers and the possibility of defining two set values of these parameters at the K-absorption edge of high-Z element present in the amino acids are discussed. The reasons for using Z PEAeff rather than the commonly used Z PIeff in medical radiation dosimetry for the calculation of absorbed dose in radiation therapy are also discussed

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

{Lambda}{bar {Lambda}} production in two-photon interactions

Energy Technology Data Exchange (ETDEWEB)

Anderson, S.; Kubota, Y.; Lattery, M.; ONeill, J.J.; Patton, S.; Poling, R.; Riehle, T.; Savinov, V.; Smith, A. [University of Minnesota, Minneapolis, Minnesota 55455 (United States); Alam, M.S.; Athar, S.B.; Ling, Z.; Mahmood, A.H.; Severini, H.; Timm, S.; Wappler, F. [State University of New York at Albany, Albany, New York 12222 (United States); Anastassov, A.; Blinov, S.; Duboscq, J.E.; Fujino, D.; Fulton, R.; Gan, K.K.; Hart, T.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.; Spencer, M.B.; Sung, M.; Undrus, A.; Wanke, R.; Wolf, A.; Zoeller, M.M. [Ohio State University, Columbus, Ohio 43210 (United States); Nemati, B.; Richichi, S.J.; Ross, W.R.; Skubic, P.; Wood, M. [University of Oklahoma, Norman, Oklahoma 73019 (United States); Bishai, M.; Fast, J.; Gerndt, E.; Hinson, J.W.; Menon, N.; Miller, D.H.; Shibata, E.I.; Shipsey, I.P.; Yurko, M. [Purdue University, West Lafayette, Indiana 47907 (United States); Gibbons, L.; Johnson, S.D.; Kwon, Y.; Roberts, S.; Thorndike, E.H. [University of Rochester, Rochester, New York 14627 (United States); Jessop, C.P.; Lingel, K.; Marsiske, H.; Perl, M.L.; Schaffner, S.F.; Ugolini, D.; Wang, R.; Zhou, X. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States); Coan, T.E.; Fadeyev, V.; Korolkov, I.; Maravin, Y.; Narsky, I.; Shelkov, V.; Staeck, J.; Stroynowski, R.; Volobouev, I.; Ye, J. [Southern Methodist University, Dallas, Texas 75275 (United States); Artuso, M.; Efimov, A.; Frasconi, F.; Gao, M.; Goldberg, M.; He, D.; Kopp, S.; Moneti, G.C.; Mountain, R.; Mukhin, Y.; Schuh, S.; Skwarnicki, T.; Stone, S.; Viehhauser, G.; Xing, X. [Syracuse University, Syracuse, New York 13244 (United States); Bartelt, J.; Csorna, S.E.; Jain, V.; Marka, S. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Freyberger, A.; Gibaut, D.; Godang, R.; Kinoshita, K.; Lai, I.C.; Pomianowski, P.; Schrenk, S.; and others

1997-09-01

Using the CLEO detector at the Cornell e{sup +}e{sup {minus}} storage ring CESR we study the two-photon production of {Lambda}{bar {Lambda}}, making the first observation of {gamma}{gamma}{r_arrow}{Lambda}{bar {Lambda}}. We present the cross section for {gamma}{gamma}{r_arrow}{Lambda}{bar {Lambda}} as a function of the {gamma}{gamma} center of mass energy and compare it to that predicted by the quark-diquark model. {copyright} {ital 1997} {ital The American Physical Society}

Measurement of the cross section for open-beauty production in photon-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, G 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; Cara Romeo, G; Carlino, G; Cartacci, A; 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; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, 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; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, F; 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; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; 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; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kraber, M; Krämer, R 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; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, 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; Novák, T; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; 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; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosemann, C; Rosenbleck, C; Rosier-Lees, S; Roth, S; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; 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; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, L; 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; Vásquez, R; 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; 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, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

2005-01-01

The cross section for open-beauty production in photon-photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity for electron-positron centre-of-mass energies from 189GeV to 209GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The e+e- -> e+e-b b~X cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations.

Quantitative mineral salt evaluation in the calcaneous bone using computed tomography, 125I-photon absorption and chemical analysis to compare the value of the individual methods

International Nuclear Information System (INIS)

Hitzler, H.J.

1983-01-01

It was the aim of the study described here to verify the accuracy of two different methods for the quantitative evaluation of mineral salts, which were the 125I-photon absorption technique on the one hand and wholebody CT on the other hand. For this purpose, post-mortem examinations of 31 calcaneous bones were carried out to evaluate their individual mineral salt contents in vitro using either of the above-mentioned methods. The results obtained were subsequently contrasted with calcium concentrations determined by chemical analysis. A comparison of the individual mineral salt evaluations with the results from calcium analyses pointed to a highly significant correlation (p=0.001) for both methods under investigation. The same held for the correlation of findings from CT and the 125I-hydroxylapatite technique, where the level of significance was also p=0.001. The above statements must, however, be modified in as much as the mineral salt values measured by CT were consistently lower than those obtained on the basis of 125I-photon absorption. These deviations are chiefly attributable to the fact that the values provided by CT are more susceptible to influences from the fat contained in the bones. In 125I-photon absorption a special formula may be derived to allow for the bias occurring here, provided that the composition of the bone is known. To summarise, the relative advantages and drawbacks of CT and 125I-photon absorption are carefully balanced. Mineral salt evaluations by CT permit incipient losses to be ascertained even in the trunk. The 125I-photon absorption technique would appear to be the obvious method for any kind of follow-up examination in the peripheral skeleton, as it is easily reproducible and radiation exposure can be kept to minimum. (TRV) [de

Multi-planar amorphous silicon photonics with compact interplanar couplers, cross talk mitigation, and low crossing loss

Directory of Open Access Journals (Sweden)

Jeff Chiles

2017-11-01

Full Text Available We propose and experimentally demonstrate a photonic routing architecture that can efficiently utilize the space of multi-plane (3D photonic integration. A wafer with three planes of amorphous silicon waveguides was fabricated and characterized, demonstrating < 3 × 1 0 − 4 dB loss per out-of-plane waveguide crossing, 0.05 ± 0.02 dB per interplane coupler, and microring resonators on three planes with a quality factors up to 8.2 × 1 0 4 . We also explore a phase velocity mapping strategy to mitigate the cross talk between co-propagating waveguides on different planes. These results expand the utility of 3D photonic integration for applications such as optical interconnects, neuromorphic computing and optical phased arrays.

Variation of energy absorption buildup factors with incident photon energy and penetration depth for some commonly used solvents

International Nuclear Information System (INIS)

Singh, Parjit S.; Singh, Tejbir; Kaur, Paramjeet

2008-01-01

G.P. fitting method has been used to compute energy absorption buildup factor of some commonly used solvents such as acetonitrile (C 4 H 3 N), butanol (C 4 H 9 OH), chlorobenzene (C 6 H 5 Cl), diethyl ether (C 4 H 10 O), ethanol (C 2 H 5 OH), methanol (CH 3 OH), propanol (C 3 H 7 OH) and water (H 2 O) for the wide energy range (0.015-15.0 MeV) up to the penetration depth of 10 mean free path. The variation of energy absorption buildup factor with chemical composition as well as incident photon energy for the selected solvents has been studied. It has been observed that the maximum value of energy absorption buildup factors shifts to the slightly higher incident photon energy with the increase in equivalent atomic number of the solvent and the solvent with least equivalent atomic number possesses the maximum value of energy absorption buildup factor

Scattering of Hawking photons as a barrier to particle absorption by black holes

International Nuclear Information System (INIS)

Funkhouser, Scott

2011-01-01

Electromagnetic scattering interactions between photons emanating from a Schwarzschild black hole and an incident charged particle should generate a repulsive force between the particle and black hole. The net scattering cross-section is calculated here as a function of the mass M of the black hole and the mass m of the particle for scenarios in which the particle is point-like and initially stationary, with proper energy ε=m, at some location far from the black hole. It follows from comparing the repulsive scattering force to the corresponding gravitational force that, in order for the particle to be drawn to the black hole, ε/T bh must be greater than a certain lower bound that is of the order 10 -3 for spin-1/2 or spin-0 particles with unit-charge. Although the scattering restriction is weaker than the requirement ε/T bh >>1 obtained independently from field-theoretic and thermodynamic treatments, the recurrence of a lower bound on the Boltzmann factor ε/T bh in limitations on particle absorption suggests a physical unity whose nature is fundamentally thermodynamic.

Sublinear absorption in OCS gas

International Nuclear Information System (INIS)

Bogani, F.; Querzoli, R.; Ernst, K.

1988-01-01

Sublinear absorption in OCS gas has been experimentally studied in detail by means of an optoacustic technique and transmission measurements. The best fit of the results is obtained by a phenomenological model, that considers the process as the sum of one-and two-photon absorptions

Two-photon stimulated emission and pulse amplification

International Nuclear Information System (INIS)

Yuen, H.P.

1975-01-01

Threshold conditions are given for the sustained operation of standing-wave and long-pulse traveling-wave two-photon lasers. Pulse shortening in long-pulse two-photon amplification, a behavior absent in the one-photon case, is also demonstrated analytically. (U.S.)

Hadronic photon-photon interactions at high energies

International Nuclear Information System (INIS)

Engel, R.; Siegen Univ.; Ranft, J.

1996-01-01

Photon-photon collisions are investigated in the framework of the two-component Dual Parton Model. The model contains contributions from direct, resolved soft and resolved hard interactions. All free parameters of the model are determined in fits to hadron-hadron and photon-hadron cross section data. The model is shown to agree well to hadron production data from hadron-hadron and photon-hadron collisions. The multiparticle production in hadron-hadron, photon-hadron and photon-photon collisions as predicted by the model is compared. Strong differences are only found as function of the transverse momentum variable. (author)

The mechanism and properties of bio-photon emission and absorption in protein molecules in living systems

Science.gov (United States)

Pang, Xiao-feng

2012-05-01

The mechanism and properties of bio-photon emission and absorption in bio-tissues were studied using Pang's theory of bio-energy transport, in which the energy spectra of protein molecules are obtained from the discrete dynamic equation. From the energy spectra, it was determined that the protein molecules could both radiate and absorb bio-photons with wavelengths of energy level transitions of the excitons. These results were consistent with the experimental data; this consisted of infrared absorption data from collagen, bovine serum albumin, the protein-like molecule acetanilide, plasma, and a person's finger, and the laser-Raman spectra of acidity I-type collagen in the lungs of a mouse, and metabolically active Escherichia coli. We further elucidated the mechanism responsible for the non-thermal biological effects produced by the infrared light absorbed by the bio-tissues, using the above results. No temperature rise was observed; instead, the absorbed infrared light promoted the vibrations of amides as well the transport of the bio-energy from one place to other in the protein molecules, which changed their conformations. These experimental results, therefore, not only confirmed the validity of the mechanism of bio-photon emission, and the newly developed theory of bio-energy transport mentioned above, but also explained the mechanism and properties of the non-thermal biological effects produced by the absorption of infrared light by the living systems.

Two-dimensional photon-echo spectroscopy at a conical intersection: A two-mode pyrazine model with dissipation

Energy Technology Data Exchange (ETDEWEB)

Sala, Matthieu; Egorova, Dassia

2016-12-20

The multi-dimensional electronic spectroscopy of ultrafast nuclear dynamics at conical intersections (CI) is an emerging field of investigation, which profits also from the recent extension of the techniques to the UV domain. We present a detailed computational study of oscillatory signatures in two-dimensional (2D) photon-echo spectroscopy (also known as 2D electronic spectroscopy, 2DES) for the two-mode pyrazine model with dissipation. Conventional 2D signals as well as the resulting beating maps are considered. Although of a reduced character, the model captures quite well all the main signatures of the excited-state dynamics of the molecule. Due to the ultrafast relaxation via the CI and no excited-state absorption from the low-lying dark state, the oscillatory components of the signal are found to be predominantly determined by the ground state bleach contribution. They reflect, therefore, the ground-state vibrational coherence induced in the Raman active mode. Beating maps provide a way to experimentally differentiate between ground state bleach and stimulated emission oscillatory components. The ultrafast decay of the latter constitutes a clear indirect signature of the CI. In the considered model, because of the sign properties of the involved transition dipole moments, the dominance of the ground-state coherence leads to anti-correlated oscillations of cross peaks located at symmetric positions with respect to the main diagonal.

New experiments call for a continuous absorption alternative to the photon model

Science.gov (United States)

Reiter, Eric S.

2015-09-01

A famous beam-split coincidence test of the photon model is described herein using gamma-rays instead of the usual visible light. A similar a new test was performed using alpha-rays. In both tests, coincidence rates greatly exceed chance, leading to an unquantum effect. In contradiction to quantum theory and the photon model, these new results are strong evidence of the long abandoned accumulation hypothesis, also known as the loading theory. Attention is drawn to assumptions applied to past key-experiments that led to quantum mechanics. The history of the loading theory is outlined, and a few equations for famous experiments are derived, now free of wave-particle duality. Quantum theory usually works because there is a subtle difference between quantized and thresholded absorption.

Inelastic scattering of neutrons by laser photons and excitons in crystals

International Nuclear Information System (INIS)

Agranovich, V.M.; Lalov, I.J.

1975-01-01

The cross section for the neutron scattering by photons sharply increases in crystals. In view of the fact that a propagating photon in a crystal (polariton), being the superposition of transverse photons and Coulomb excitations (optical phonons, excitons, etc.), involves in the motion also a nucleus subsystem, the cross section for the neutron scattering on the photon turns out to be proportional to the cross section for neutron scattering on nuclei and to the strength function of phonons at the polariton frequency. Numerical estimates for the cross section of the noncoherent photon absorption by a neutron in the case of a LiH crystal in the presence of an intense, electromagnetic radiation point to the possibility of an action of neutron fluxes by laser radiation. A similar effect of involvement (superposition) also takes place for excitons. This fact can be used for calculations of the cross section for neutron inelastic scattering by excitons, which is proportional to the scattering of neutron on nuclei cross section. The paper also discussed the effect of laser radiation of neutron-induced nuclear reaction (radiative capture and threshold reactions)

Absorption cross-section measurements of methane, ethane, ethylene and methanol at high temperatures

KAUST Repository

Alrefae, Majed

2014-09-01

Mid-IR absorption cross-sections are measured for methane, ethane, ethylene and methanol over 2800-3400 cm-1 (2.9-3.6 μm) spectral region. Measurements are carried out using a Fourier-Transform-Infrared (FTIR) spectrometer with temperatures ranging 296-1100 K and pressures near atmospheric. As temperature increases, the peak cross-sections decrease but the wings of the bands increase as higher rotational lines appear. Integrated band intensity is also calculated over the measured spectral region and is found to be a very weak function of temperature. The absorption cross-sections of the relatively small fuels studied here show dependence on the bath gas. This effect is investigated by studying the variation of absorption cross-sections at 3.392 μm using a HeNe laser in mixtures of fuel and nitrogen, argon, or helium. Mixtures of fuel with He have the highest value of absorption cross-sections followed by Ar and N2. Molecules with narrow absorption lines, such as methane and methanol, show strong dependence on bath gas than molecules with relatively broader absorption features i.e. ethane and ethylene. © 2014 Elsevier Inc. All rights reserved.

Δ excitation in 3He and 4He by photons

International Nuclear Information System (INIS)

Maruyama, Koichi.

1993-06-01

The use of the 3 He and 4 He photodisintegration reactions in the study of the excitation, propagation, and decay of the Δ (1232) in these nuclei is proposed. By using the data obtained with TAGX for both photon absorption on neutron-proton pairs and complete photodisintegration, we find no compelling evidence for the change of the Δ property in the 3 He and 4 He nuclei. It is also proposed to use nuclear photodisintegration in the search for the excitation of the higher-mass nucleon resonances whose absence in the total photon-absorption cross sections in nuclei is reported recently. (author)

Self-assembly of Terbium(III)-based metal-organic complexes with two-photon absorbing active

Science.gov (United States)

Li, Dandan; Shao, Nanqi; Sun, Xianshun; Zhang, Guocui; Li, Shengli; Zhou, Hongping; Wu, Jieying; Tian, Yupeng

2014-12-01

Hybrid complexes based on D-π-A type dyes p-aminostyryl-pyridinum and Terbium(III) complex anion (1, 2) have been synthesized by ionic exchange reaction. Meanwhile two different alkyl-substituted amino groups were used as electron donors in organic dyes cations. The synthesized complexes were characterized by element analysis. In addition, the structural features of them were systematic studied by single crystal X-ray diffraction analysis. Their linear properties have been systematically investigated by absorption spectra and fluorescence, the results show that the energy transfer takes place from the trans-4-[4‧-(N,N-diethylamino)styryl]-N-methyl pyridinium (2‧) cation to Tb(III). In addition, complex 2 exhibit a large two-photon absorption coefficient β: 0.044 cm/GW at 710 nm.

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.

Measurement of the inclusive isolated prompt photon production cross section at the Tevatron using the CDF detector

International Nuclear Information System (INIS)

Deluca Silberberg, Carolina

2009-01-01

In this thesis we present the measurement of the inclusive isolated prompt photon cross section with a total integrated luminosity of 2.5 fb -1 of data collected with the CDF Run II detector at the Fermilab Tevatron Collider. The prompt photon cross section is a classic measurement to test perturbative QCD (pQCD) with potential to provide information on the parton distribution function (PDF), and sensitive to the presence of new physics at large photon transverse momentum. Prompt photons also constitute an irreducible background for important searches such as H → γγ, or SUSY and extra-dimensions with energetic photons in the final state. The Tevatron at Fermilab (Batavia, U.S.A.) is currently the hadron collider that operates at the highest energies in the world. It collides protons and antiprotons with a center-of-mass energy of 1.96 TeV. The CDF and the D0 experiments are located in two of its four interaction regions. In Run I at the Tevatron, the direct photon production cross section was measured by both CDF and DO, and first results in Run II have been presented by the DO Collaboration based on 380 pb -1 . Both Run I and Run II results show agreement with the theoretical predictions except for the low p T γ region, where the observed and predicted shapes are different. Prompt photon production has been also extensively measured at fixed-target experiments in lower p T γ ranges, showing excess of data compared to the theory, particularly at high x T . From an experimental point of view, the study of the direct photon production has several advantages compared to QCD studies using jets. Electromagnetic calorimeters have better energy resolution than hadronic calorimeters, and the systematic uncertainty on the photon absolute energy scale is smaller. Furthermore, the determination of the photon kinematics does not require the use of jet algorithms. However, the measurements using photons require a good understanding of the background, mainly dominated by

Measurement of the total photon-photon cross section for the production of hadrons at small Q2

International Nuclear Information System (INIS)

Berger, C.; Deuter, A.; Genzel, H.; Lackas, W.; Pielorz, J.; Raupach, F.; Wagner, W.; Bussey, P.J.; Cartwright, S.L.; Dainton, J.B.; King, B.T.; Raine, C.; Scarr, J.M.; Skillicorn, I.O.; Smith, K.M.; Thomson, J.C.; Achterberg, O.; Blobel, V.; Burkart, D.; Diehlmann, K.; Feindt, M.; Kapitza, H.; Koppitz, B.; Krueger, M.; Poppe, M.; Spitzer, H.; Staa, R. van; Almeida, F.; Baecker, A.; Barreiro, F.; Brandt, S.; Derikum, K.; Grupen, C.; Meyer, H.J.; Mueller, H.; Neumann, B.; Rost, M.; Stupperich, K.; Zech, G.; Alexander, G.; Bella, G.; Gnat, Y.; Grunhaus, J.; Junge, H.; Kraski, K.; Maxeiner, C.; Maxeiner, H.; Meyer, H.; Schmidt, D.; Buerger, J.; Criegee, L.; Ferrarotto, F.; Franke, G.; Gaspero, M.; Gerke, C.; Knies, G.; Lewendel, B.; Meyer, J.; Michelsen, U.; Pape, K.H.; Stella, B.; Timm, U.; Winter, G.G.; Zachara, M.; Zimmermann, W.

1984-09-01

The total photon-photon cross section for the production of hadrons, sigmasub(γγ)(W,Q 2 ), has been measured in the single tag condition for 0.1 2 2 and 1.5 2 dependence of sigmasub(γγ) averaged over W can be described by GVDM. The dependence of sigmasub(γγ) on the mass W of the hadronic final state has been extracted at Q 2 =0.44 GeV 2 by unfolding the effects of experimental resolution and acceptance. The cross section is found to rise at small W. The result is compared with VDM and the parton model. (orig.)

Electrically Induced Two-Photon Transparency in Semiconductor Quantum Wells

International Nuclear Information System (INIS)

Hayat, Alex; Nevet, Amir; Orenstein, Meir

2009-01-01

We demonstrate experimentally two-photon transparency, achieved by current injection into a semiconductor quantum-well structure which exhibits two-photon emission. The two-photon induced luminescence is progressively reduced by the injected current, reaching the point of two-photon transparency - a necessary condition for semiconductor two-photon gain and lasing. These results agree with our calculations.

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 partial decay widths of the χc 0 and χc 2 mesons are measured as a function of Q2 based on 10 candidate events in total.

Design of photonic bandgap fibers by topology optimization

DEFF Research Database (Denmark)

Dühring, Maria Bayard; Sigmund, Ole; Feurer, Thomas

2010-01-01

A method based on topology optimization is presented to design the cross section of hollow-core photonic bandgap fibers for minimizing energy loss by material absorption. The optical problem is modeled by the timeharmonic wave equation and solved with the finite element program Comsol Multiphysics...

Measurement of the Differential Cross Section for Isolated Prompt Photon Production in pp Collisions at 7 TeV

Energy Technology Data Exchange (ETDEWEB)

Chatrchyan, S. [Yerevan Physics Institute (Armenia); et al.,

2011-09-01

A measurement of the differential cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 36 inverse picobarns recorded by the CMS detector at the LHC. The measurement covers the pseudorapidity range |eta|<2.5 and the transverse energy range 25 < ET < 400 GeV, corresponding to the kinematic region 0.007 < xT < 0.114. Photon candidates are identified with two complementary methods, one based on photon conversions in the silicon tracker and the other on isolated energy deposits in the electromagnetic calorimeter. The measured cross section is presented as a function of ET in four pseudorapidity regions. The next-to-leading-order perturbative QCD calculations are consistent with the measured cross section.

Measurement of the Differential Cross Section for Isolated Prompt Photon Production in pp Collisions at 7 TeV

CERN Document Server

Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hammer, Josef; Haensel, Stephan; Hoch, Michael; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Krammer, Manfred; Liko, Dietrich; Mikulec, Ivan; Pernicka, Manfred; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Teischinger, Florian; Trauner, Christine; Wagner, Philipp; Waltenberger, Wolfgang; Walzel, Gerhard; Widl, Edmund; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Bansal, Sunil; Benucci, Leonardo; De Wolf, Eddi A; Janssen, Xavier; Luyckx, Sten; Maes, Thomas; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Selvaggi, Michele; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Gonzalez Suarez, Rebeca; Kalogeropoulos, Alexis; Maes, Michael; Olbrechts, Annik; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Charaf, Otman; Clerbaux, Barbara; De Lentdecker, Gilles; Dero, Vincent; Gay, Arnaud; Hammad, Gregory Habib; Hreus, Tomas; Marage, Pierre Edouard; Raval, Amita; Thomas, Laurent; Vander Marcken, Gil; Vander Velde, Catherine; Vanlaer, Pascal; Adler, Volker; Cimmino, Anna; Costantini, Silvia; Grunewald, Martin; Klein, Benjamin; Lellouch, Jérémie; Marinov, Andrey; Mccartin, Joseph; Ryckbosch, Dirk; Thyssen, Filip; Tytgat, Michael; Vanelderen, Lukas; Verwilligen, Piet; Walsh, Sinead; Zaganidis, Nicolas; Basegmez, Suzan; Bruno, Giacomo; Caudron, Julien; Ceard, Ludivine; Cortina Gil, Eduardo; De Favereau De Jeneret, Jerome; Delaere, Christophe; Favart, Denis; Giammanco, Andrea; Grégoire, Ghislain; Hollar, Jonathan; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Nuttens, Claude; Ovyn, Severine; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Schul, Nicolas; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Alves, Gilvan; Brito, Lucas; De Jesus Damiao, Dilson; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Melo Da Costa, Eliza; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Oguri, Vitor; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Silva Do Amaral, Sheila Mara; Sznajder, Andre; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Dos Anjos Costa, Tiago; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Da Cunha Marinho, Franciole; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Darmenov, Nikolay; Genchev, Vladimir; Iaydjiev, Plamen; Piperov, Stefan; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Tcholakov, Vanio; Trayanov, Rumen; Vutova, Mariana; Dimitrov, Anton; Hadjiiska, Roumyana; Karadzhinova, Aneliya; Kozhuharov, Venelin; Litov, Leander; Mateev, Matey; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Tao, Junquan; Wang, Jian; Wang, Jian; Wang, Xianyou; Wang, Zheng; Xiao, Hong; Xu, Ming; Zang, Jingjing; Zhang, Zhen; Ban, Yong; Guo, Shuang; Guo, Yifei; Li, Wenbo; Mao, Yajun; Qian, Si-Jin; Teng, Haiyun; Zhu, Bo; Zou, Wei; Cabrera, Andrés; Gomez Moreno, Bernardo; Ocampo Rios, Alberto Andres; Osorio Oliveros, Andres Felipe; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Lelas, Karlo; Plestina, Roko; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Dzelalija, Mile; Kovac, Marko; Brigljevic, Vuko; Duric, Senka; Kadija, Kreso; Luetic, Jelena; Morovic, Srecko; Attikis, Alexandros; Galanti, Mario; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Ellithi Kamel, Ali; Khalil, Shaaban; Mahmoud, Mohammed; Radi, Amr; Hektor, Andi; Kadastik, Mario; Müntel, Mait; Raidal, Martti; Rebane, Liis; Tiko, Andres; Azzolini, Virginia; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Czellar, Sandor; Härkönen, Jaakko; Heikkinen, Mika Aatos; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Ungaro, Donatella; Wendland, Lauri; Banzuzi, Kukka; Karjalainen, Ahti; Korpela, Arja; Tuuva, Tuure; Sillou, Daniel; Besancon, Marc; Choudhury, Somnath; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Gentit, François-Xavier; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Marionneau, Matthieu; Millischer, Laurent; Rander, John; Rosowsky, André; Shreyber, Irina; Titov, Maksym; Verrecchia, Patrice; Baffioni, Stephanie; Beaudette, Florian; Benhabib, Lamia; Bianchini, Lorenzo; Bluj, Michal; Broutin, Clementine; Busson, Philippe; Charlot, Claude; Dahms, Torsten; Dobrzynski, Ludwik; Elgammal, Sherif; Granier de Cassagnac, Raphael; Haguenauer, Maurice; Miné, Philippe; Mironov, Camelia; Ochando, Christophe; Paganini, Pascal; Sabes, David; Salerno, Roberto; Sirois, Yves; Thiebaux, Christophe; Wyslouch, Bolek; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Bodin, David; Brom, Jean-Marie; Cardaci, Marco; Chabert, Eric Christian; Collard, Caroline; Conte, Eric; Drouhin, Frédéric; Ferro, Cristina; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Greder, Sebastien; Juillot, Pierre; Karim, Mehdi; Le Bihan, Anne-Catherine; Mikami, Yoshinari; Van Hove, Pierre; Fassi, Farida; Mercier, Damien; Baty, Clement; Beauceron, Stephanie; Beaupere, Nicolas; Bedjidian, Marc; Bondu, Olivier; Boudoul, Gaelle; Boumediene, Djamel; Brun, Hugues; Chasserat, Julien; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fay, Jean; Gascon, Susan; Ille, Bernard; Kurca, Tibor; Le Grand, Thomas; Lethuillier, Morgan; Mirabito, Laurent; Perries, Stephane; Sordini, Viola; Tosi, Silvano; Tschudi, Yohann; Verdier, Patrice; Viret, Sébastien; Lomidze, David; Anagnostou, Georgios; Beranek, Sarah; Edelhoff, Matthias; Feld, Lutz; Heracleous, Natalie; Hindrichs, Otto; Jussen, Ruediger; Klein, Katja; Merz, Jennifer; Mohr, Niklas; Ostapchuk, Andrey; Perieanu, Adrian; Raupach, Frank; Sammet, Jan; Schael, Stefan; Sprenger, Daniel; Weber, Hendrik; Weber, Martin; Wittmer, Bruno; Ata, Metin; Dietz-Laursonn, Erik; Erdmann, Martin; Hebbeker, Thomas; Heidemann, Carsten; Hinzmann, Andreas; Hoepfner, Kerstin; Klimkovich, Tatsiana; Klingebiel, Dennis; Kreuzer, Peter; Lanske, Dankfried; Lingemann, Joschka; Magass, Carsten; Merschmeyer, Markus; Meyer, Arnd; Papacz, Paul; Pieta, Holger; Reithler, Hans; Schmitz, Stefan Antonius; Sonnenschein, Lars; Steggemann, Jan; Teyssier, Daniel; Bontenackels, Michael; Cherepanov, Vladimir; Davids, Martina; Duda, Markus; Flügge, Günter; Geenen, Heiko; Giffels, Manuel; Haj Ahmad, Wael; Heydhausen, Dirk; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Kuessel, Yvonne; Linn, Alexander; Nowack, Andreas; Perchalla, Lars; Pooth, Oliver; Rennefeld, Jörg; Sauerland, Philip; Stahl, Achim; Tornier, Daiske; Zoeller, Marc Henning; Aldaya Martin, Maria; Behrenhoff, Wolf; Behrens, Ulf; Bergholz, Matthias; Bethani, Agni; Borras, Kerstin; Cakir, Altan; Campbell, Alan; Castro, Elena; Dammann, Dirk; Eckerlin, Guenter; Eckstein, Doris; Flossdorf, Alexander; Flucke, Gero; Geiser, Achim; Hauk, Johannes; Jung, Hannes; Kasemann, Matthias; Katsas, Panagiotis; Kleinwort, Claus; Kluge, Hannelies; Knutsson, Albert; Krämer, Mira; Krücker, Dirk; Kuznetsova, Ekaterina; Lange, Wolfgang; Lohmann, Wolfgang; Mankel, Rainer; Marienfeld, Markus; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mnich, Joachim; Mussgiller, Andreas; Olzem, Jan; Petrukhin, Alexey; Pitzl, Daniel; Raspereza, Alexei; Rosin, Michele; Schmidt, Ringo; Schoerner-Sadenius, Thomas; Sen, Niladri; Spiridonov, Alexander; Stein, Matthias; Tomaszewska, Justyna; Walsh, Roberval; Wissing, Christoph; Autermann, Christian; Blobel, Volker; Bobrovskyi, Sergei; Draeger, Jula; Enderle, Holger; Gebbert, Ulla; Görner, Martin; Hermanns, Thomas; Kaschube, Kolja; Kaussen, Gordon; Kirschenmann, Henning; Klanner, Robert; Lange, Jörn; Mura, Benedikt; Naumann-Emme, Sebastian; Nowak, Friederike; Pietsch, Niklas; Sander, Christian; Schettler, Hannes; Schleper, Peter; Schlieckau, Eike; Schröder, Matthias; Schum, Torben; Stadie, Hartmut; Steinbrück, Georg; Thomsen, Jan; Barth, Christian; Bauer, Julia; Berger, Joram; Buege, Volker; Chwalek, Thorsten; De Boer, Wim; Dierlamm, Alexander; Dirkes, Guido; Feindt, Michael; Gruschke, Jasmin; Hackstein, Christoph; Hartmann, Frank; Heinrich, Michael; Held, Hauke; Hoffmann, Karl-Heinz; Honc, Simon; Katkov, Igor; Komaragiri, Jyothsna Rani; Kuhr, Thomas; Martschei, Daniel; Mueller, Steffen; Müller, Thomas; Niegel, Martin; Oberst, Oliver; Oehler, Andreas; Ott, Jochen; Peiffer, Thomas; Quast, Gunter; Rabbertz, Klaus; Ratnikov, Fedor; Ratnikova, Natalia; Renz, Manuel; Saout, Christophe; Scheurer, Armin; Schieferdecker, Philipp; Schilling, Frank-Peter; Schott, Gregory; Simonis, Hans-Jürgen; Stober, Fred-Markus Helmut; Troendle, Daniel; Wagner-Kuhr, Jeannine; Weiler, Thomas; Zeise, Manuel; Zhukov, Valery; Ziebarth, Eva Barbara; Daskalakis, Georgios; Geralis, Theodoros; Kesisoglou, Stilianos; Kyriakis, Aristotelis; Loukas, Demetrios; Manolakos, Ioannis; Markou, Athanasios; Markou, Christos; Mavrommatis, Charalampos; Ntomari, Eleni; Petrakou, Eleni; Gouskos, Loukas; Mertzimekis, Theodoros; Panagiotou, Apostolos; Saoulidou, Niki; Stiliaris, Efstathios; Evangelou, Ioannis; Foudas, Costas; Kokkas, Panagiotis; Manthos, Nikolaos; Papadopoulos, Ioannis; Patras, Vaios; Triantis, Frixos A; Aranyi, Attila; Bencze, Gyorgy; Boldizsar, Laszlo; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Kapusi, Anita; Krajczar, Krisztian; Sikler, Ferenc; Veres, Gabor Istvan; Vesztergombi, Gyorgy; Beni, Noemi; Molnar, Jozsef; Palinkas, Jozsef; Szillasi, Zoltan; Veszpremi, Viktor; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Beri, Suman Bala; Bhatnagar, Vipin; Dhingra, Nitish; Gupta, Ruchi; Jindal, Monika; Kaur, Manjit; Kohli, Jatinder Mohan; Mehta, Manuk Zubin; Nishu, Nishu; Saini, Lovedeep Kaur; Sharma, Archana; Singh, Anil; Singh, Jasbir; Singh, Supreet Pal; Ahuja, Sudha; Choudhary, Brajesh C; Gupta, Pooja; Kumar, Ashok; Kumar, Arun; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Shivpuri, Ram Krishen; Banerjee, Sunanda; Bhattacharya, Satyaki; Dutta, Suchandra; Gomber, Bhawna; Jain, Sandhya; Jain, Shilpi; Khurana, Raman; Sarkar, Subir; Choudhury, Rajani Kant; Dutta, Dipanwita; Kailas, Swaminathan; Kumar, Vineet; Mehta, Pourus; Mohanty, Ajit Kumar; Pant, Lalit Mohan; Shukla, Prashant; Aziz, Tariq; Guchait, Monoranjan; Gurtu, Atul; Maity, Manas; Majumder, Devdatta; Majumder, Gobinda; Mazumdar, Kajari; Mohanty, Gagan Bihari; Saha, Anirban; Sudhakar, Katta; Wickramage, Nadeesha; Banerjee, Sudeshna; Dugad, Shashikant; Mondal, Naba Kumar; Arfaei, Hessamaddin; Bakhshiansohi, Hamed; Etesami, Seyed Mohsen; Fahim, Ali; Hashemi, Majid; Hesari, Hoda; Jafari, Abideh; Khakzad, Mohsen; Mohammadi, Abdollah; Mohammadi Najafabadi, Mojtaba; Paktinat Mehdiabadi, Saeid; Safarzadeh, Batool; Zeinali, Maryam; Abbrescia, Marcello; Barbone, Lucia; Calabria, Cesare; Colaleo, Anna; Creanza, Donato; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Lusito, Letizia; Maggi, Giorgio; Maggi, Marcello; Manna, Norman; Marangelli, Bartolomeo; My, Salvatore; Nuzzo, Salvatore; Pacifico, Nicola; Pierro, Giuseppe Antonio; Pompili, Alexis; Pugliese, Gabriella; Romano, Francesco; Roselli, Giuseppe; Selvaggi, Giovanna; Silvestris, Lucia; Trentadue, Raffaello; Tupputi, Salvatore; Zito, Giuseppe; Abbiendi, Giovanni; Benvenuti, Alberto; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Giunta, Marina; Grandi, Claudio; Marcellini, Stefano; Masetti, Gianni; Meneghelli, Marco; Montanari, Alessandro; Navarria, Francesco; Odorici, Fabrizio; Perrotta, Andrea; Primavera, Federica; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gianni; Travaglini, Riccardo; Albergo, Sebastiano; Cappello, Gigi; Chiorboli, Massimiliano; Costa, Salvatore; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Frosali, Simone; Gallo, Elisabetta; Gonzi, Sandro; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Tropiano, Antonio; Benussi, Luigi; Bianco, Stefano; Colafranceschi, Stefano; Fabbri, Franco; Piccolo, Davide; Fabbricatore, Pasquale; Musenich, Riccardo; Benaglia, Andrea; De Guio, Federico; Di Matteo, Leonardo; Gennai, Simone; Ghezzi, Alessio; Malvezzi, Sandra; Martelli, Arabella; Massironi, Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Redaelli, Nicola; Sala, Silvano; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Carrillo Montoya, Camilo Andres; Cavallo, Nicola; De Cosa, Annapaola; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lista, Luca; Merola, Mario; Paolucci, Pierluigi; Azzi, Patrizia; Bacchetta, Nicola; Bellan, Paolo; Bisello, Dario; Branca, Antonio; Carlin, Roberto; Checchia, Paolo; Dorigo, Tommaso; Dosselli, Umberto; Fanzago, Federica; Gasparini, Fabrizio; Gasparini, Ugo; Gozzelino, Andrea; Lacaprara, Stefano; Lazzizzera, Ignazio; Margoni, Martino; Mazzucato, Mirco; Meneguzzo, Anna Teresa; Nespolo, Massimo; Perrozzi, Luca; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Tosi, Mia; Vanini, Sara; Zotto, Pierluigi; Zumerle, Gianni; Baesso, Paolo; Berzano, Umberto; Ratti, Sergio P; Riccardi, Cristina; Torre, Paola; Vitulo, Paolo; Viviani, Claudio; Biasini, Maurizio; Bilei, Gian Mario; Caponeri, Benedetta; Fanò, Livio; Lariccia, Paolo; Lucaroni, Andrea; Mantovani, Giancarlo; Menichelli, Mauro; Nappi, Aniello; Romeo, Francesco; Santocchia, Attilio; Taroni, Silvia; Valdata, Marisa; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Broccolo, Giuseppe; Castaldi, Rino; D'Agnolo, Raffaele Tito; Dell'Orso, Roberto; Fiori, Francesco; Foà, Lorenzo; Giassi, Alessandro; Kraan, Aafke; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Palla, Fabrizio; Palmonari, Francesco; Segneri, Gabriele; Serban, Alin Titus; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Del Re, Daniele; Di Marco, Emanuele; Diemoz, Marcella; Franci, Daniele; Grassi, Marco; Longo, Egidio; Meridiani, Paolo; Nourbakhsh, Shervin; Organtini, Giovanni; Pandolfi, Francesco; Paramatti, Riccardo; Rahatlou, Shahram; Sigamani, Michael; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Biino, Cristina; Botta, Cristina; Cartiglia, Nicolo; Castello, Roberto; Costa, Marco; Demaria, Natale; Graziano, Alberto; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Musich, Marco; Obertino, Maria Margherita; Pastrone, Nadia; Pelliccioni, Mario; Potenza, Alberto; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Vilela Pereira, Antonio; Belforte, Stefano; Cossutti, Fabio; Della Ricca, Giuseppe; Gobbo, Benigno; Marone, Matteo; Montanino, Damiana; Penzo, Aldo; Heo, Seong Gu; Nam, Soon-Kwon; Chang, Sunghyun; Chung, Jin Hyuk; Kim, Dong Hee; Kim, Gui Nyun; Kim, Ji Eun; Kong, Dae Jung; Park, Hyangkyu; Ro, Sang-Ryul; Son, Dong-Chul; Son, Taejin; Kim, Jae Yool; Kim, Zero Jaeho; Song, Sanghyeon; Jo, Hyun Yong; Choi, Suyong; Gyun, Dooyeon; Hong, Byung-Sik; Jo, Mihee; Kim, Hyunchul; Kim, Ji Hyun; Kim, Tae Jeong; Lee, Kyong Sei; Moon, Dong Ho; Park, Sung Keun; Seo, Eunsung; Sim, Kwang Souk; Choi, Minkyoo; Kang, Seokon; Kim, Hyunyong; Park, Chawon; Park, Inkyu; Park, Sangnam; Ryu, Geonmo; Cho, Yongjin; Choi, Young-Il; Choi, Young Kyu; Goh, Junghwan; Kim, Min Suk; Lee, Byounghoon; Lee, Jongseok; Lee, Sungeun; Seo, Hyunkwan; Yu, Intae; Bilinskas, Mykolas Jurgis; Grigelionis, Ignas; Janulis, Mindaugas; Martisiute, Dalia; Petrov, Pavel; Polujanskas, Mindaugas; Sabonis, Tomas; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-de La Cruz, Ivan; Lopez-Fernandez, Ricardo; Magaña Villalba, Ricardo; Martínez-Ortega, Jorge; Sánchez-Hernández, Alberto; Villasenor-Cendejas, Luis Manuel; Carrillo Moreno, Salvador; Vazquez Valencia, Fabiola; Salazar Ibarguen, Humberto Antonio; Casimiro Linares, Edgar; Morelos Pineda, Antonio; Reyes-Santos, Marco A; Krofcheck, David; Tam, Jason; Butler, Philip H; Doesburg, Robert; Silverwood, Hamish; Ahmad, Muhammad; Ahmed, Ijaz; Ansari, Muhammad Hamid; Asghar, Muhammad Irfan; Hoorani, Hafeez R; Khalid, Shoaib; Khan, Wajid Ali; Khurshid, Taimoor; Qazi, Shamona; Shah, Mehar Ali; Shoaib, Muhammad; Brona, Grzegorz; Cwiok, Mikolaj; Dominik, Wojciech; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Frueboes, Tomasz; Gokieli, Ryszard; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Wrochna, Grzegorz; Zalewski, Piotr; Almeida, Nuno; Bargassa, Pedrame; David Tinoco Mendes, Andre; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Musella, Pasquale; Nayak, Aruna; Pela, Joao; Ribeiro, Pedro Quinaz; Seixas, Joao; Varela, Joao; Afanasiev, Serguei; Belotelov, Ivan; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Kamenev, Alexey; Karjavin, Vladimir; Kozlov, Guennady; Lanev, Alexander; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Smirnov, Vitaly; Volodko, Anton; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Matveev, Viktor; Pashenkov, Anatoli; Toropin, Alexander; Troitsky, Sergey; Epshteyn, Vladimir; Erofeeva, Maria; Gavrilov, Vladimir; Kaftanov, Vitali; Kossov, Mikhail; Krokhotin, Andrey; Lychkovskaya, Natalia; Popov, Vladimir; Safronov, Grigory; Semenov, Sergey; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Kodolova, Olga; Lokhtin, Igor; Markina, Anastasia; Obraztsov, Stepan; Perfilov, Maxim; Petrushanko, Sergey; Sarycheva, Ludmila; Savrin, Viktor; Snigirev, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Grishin, Viatcheslav; Kachanov, Vassili; Konstantinov, Dmitri; Korablev, Andrey; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Djordjevic, Milos; Krpic, Dragomir; Milosevic, Jovan; Aguilar-Benitez, Manuel; Alcaraz Maestre, Juan; Arce, Pedro; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Diez Pardos, Carmen; Domínguez Vázquez, Daniel; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Ferrando, Antonio; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Merino, Gonzalo; Puerta Pelayo, Jesus; Redondo, Ignacio; Romero, Luciano; Santaolalla, Javier; Senghi Soares, Mara; Willmott, Carlos; Albajar, Carmen; Codispoti, Giuseppe; de Trocóniz, Jorge F; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Lloret Iglesias, Lara; Vizan Garcia, Jesus Manuel; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Chuang, Shan-Huei; Duarte Campderros, Jordi; Felcini, Marta; Fernandez, Marcos; Gomez, Gervasio; Gonzalez Sanchez, Javier; Jorda, Clara; Lobelle Pardo, Patricia; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Sobron Sanudo, Mar; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Baillon, Paul; Ball, Austin; Barney, David; Bell, Alan James; Benedetti, Daniele; Bernet, Colin; Bialas, Wojciech; Bloch, Philippe; Bocci, Andrea; Bolognesi, Sara; Bona, Marcella; Breuker, Horst; Bunkowski, Karol; Camporesi, Tiziano; Cerminara, Gianluca; Christiansen, Tim; Coarasa Perez, Jose Antonio; Curé, Benoît; D'Enterria, David; De Roeck, Albert; Di Guida, Salvatore; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Frisch, Benjamin; Funk, Wolfgang; Gaddi, Andrea; Georgiou, Georgios; Gerwig, Hubert; Gigi, Dominique; Gill, Karl; Giordano, Domenico; Glege, Frank; Gomez-Reino Garrido, Robert; Gouzevitch, Maxime; Govoni, Pietro; Gowdy, Stephen; Guida, Roberto; Guiducci, Luigi; Hansen, Magnus; Hartl, Christian; Harvey, John; Hegeman, Jeroen; Hegner, Benedikt; Hoffmann, Hans Falk; Innocente, Vincenzo; Janot, Patrick; Kaadze, Ketino; Karavakis, Edward; Lecoq, Paul; Lourenco, Carlos; Maki, Tuula; Malberti, Martina; Malgeri, Luca; Mannelli, Marcello; Masetti, Lorenzo; Maurisset, Aurelie; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moser, Roland; Mozer, Matthias Ulrich; Mulders, Martijn; Nesvold, Erik; Nguyen, Matthew; Orimoto, Toyoko; Orsini, Luciano; Palencia Cortezon, Enrique; Perez, Emmanuelle; Petrilli, Achille; Pfeiffer, Andreas; Pierini, Maurizio; Pimiä, Martti; Piparo, Danilo; Polese, Giovanni; Quertenmont, Loic; Racz, Attila; Reece, William; Rodrigues Antunes, Joao; Rolandi, Gigi; Rommerskirchen, Tanja; Rovelli, Chiara; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Segoni, Ilaria; Sharma, Archana; Siegrist, Patrice; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Spiga, Daniele; Spiropulu, Maria; Stoye, Markus; Tsirou, Andromachi; Vichoudis, Paschalis; Wöhri, Hermine Katharina; Worm, Steven; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Gabathuler, Kurt; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; König, Stefan; Kotlinski, Danek; Langenegger, Urs; Meier, Frank; Renker, Dieter; Rohe, Tilman; Sibille, Jennifer; Bäni, Lukas; Bortignon, Pierluigi; Caminada, Lea; Casal, Bruno; Chanon, Nicolas; Chen, Zhiling; Cittolin, Sergio; Dissertori, Günther; Dittmar, Michael; Eugster, Jürg; Freudenreich, Klaus; Grab, Christoph; Hintz, Wieland; Lecomte, Pierre; Lustermann, Werner; Marchica, Carmelo; Martinez Ruiz del Arbol, Pablo; Milenovic, Predrag; Moortgat, Filip; Nägeli, Christoph; Nef, Pascal; Nessi-Tedaldi, Francesca; Pape, Luc; Pauss, Felicitas; Punz, Thomas; Rizzi, Andrea; Ronga, Frederic Jean; Rossini, Marco; Sala, Leonardo; Sanchez, Ann - Karin; Sawley, Marie-Christine; Starodumov, Andrei; Stieger, Benjamin; Takahashi, Maiko; Tauscher, Ludwig; Thea, Alessandro; Theofilatos, Konstantinos; Treille, Daniel; Urscheler, Christina; Wallny, Rainer; Weber, Matthias; Wehrli, Lukas; Weng, Joanna; Aguilo, Ernest; Amsler, Claude; Chiochia, Vincenzo; De Visscher, Simon; Favaro, Carlotta; Ivova Rikova, Mirena; Jaeger, Andreas; Millan Mejias, Barbara; Otiougova, Polina; Robmann, Peter; Schmidt, Alexander; Snoek, Hella; Chang, Yuan-Hann; Chen, Kuan-Hsin; Kuo, Chia-Ming; Li, Syue-Wei; Lin, Willis; Liu, Zong-Kai; Lu, Yun-Ju; Mekterovic, Darko; Volpe, Roberta; Yu, Shin-Shan; Bartalini, Paolo; Chang, Paoti; Chang, You-Hao; Chang, Yu-Wei; Chao, Yuan; Chen, Kai-Feng; Hou, George Wei-Shu; Hsiung, Yee; Kao, Kai-Yi; Lei, Yeong-Jyi; Lu, Rong-Shyang; Shiu, Jing-Ge; Tzeng, Yeng-Ming; Wan, Xia; Wang, Minzu; Adiguzel, Aytul; Bakirci, Mustafa Numan; Cerci, Salim; Dozen, Candan; Dumanoglu, Isa; Eskut, Eda; Girgis, Semiray; Gokbulut, Gul; Hos, Ilknur; Kangal, Evrim Ersin; Kayis Topaksu, Aysel; 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Akgun, Bora; Carroll, Ryan; Ferguson, Thomas; Iiyama, Yutaro; Jang, Dong Wook; Jun, Soon Yung; Liu, Yueh-Feng; Paulini, Manfred; Russ, James; Vogel, Helmut; Vorobiev, Igor; Cumalat, John Perry; Dinardo, Mauro Emanuele; Drell, Brian Robert; Edelmaier, Christopher; Ford, William T; Gaz, Alessandro; Heyburn, Bernadette; Luiggi Lopez, Eduardo; Nauenberg, Uriel; Smith, James; Stenson, Kevin; Ulmer, Keith; Wagner, Stephen Robert; Zang, Shi-Lei; Agostino, Lorenzo; Alexander, James; Chatterjee, Avishek; Eggert, Nicholas; Gibbons, Lawrence Kent; Heltsley, Brian; Henriksson, Kristofer; Hopkins, Walter; Khukhunaishvili, Aleko; Kreis, Benjamin; Liu, Yao; Nicolas Kaufman, Gala; Patterson, Juliet Ritchie; Puigh, Darren; Ryd, Anders; Saelim, Michael; Salvati, Emmanuele; Shi, Xin; Sun, Werner; Teo, Wee Don; Thom, Julia; Thompson, Joshua; Vaughan, Jennifer; Weng, Yao; Winstrom, Lucas; Wittich, Peter; Biselli, Angela; Cirino, Guy; Winn, Dave; Abdullin, Salavat; Albrow, Michael; Anderson, Jacob; Apollinari, Giorgio; Atac, Muzaffer; Bakken, Jon Alan; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Bloch, Ingo; Burkett, Kevin; Butler, Joel Nathan; Chetluru, Vasundhara; Cheung, Harry; Chlebana, Frank; Cihangir, Selcuk; Cooper, William; Eartly, David P; Elvira, Victor Daniel; Esen, Selda; Fisk, Ian; Freeman, Jim; Gao, Yanyan; Gottschalk, Erik; Green, Dan; Gunthoti, Kranti; Gutsche, Oliver; Hanlon, Jim; Harris, Robert M; Hirschauer, James; Hooberman, Benjamin; Jensen, Hans; Johnson, Marvin; Joshi, Umesh; Khatiwada, Rakshya; Klima, Boaz; Kousouris, Konstantinos; Kunori, Shuichi; Kwan, Simon; Leonidopoulos, Christos; Limon, Peter; Lincoln, Don; Lipton, Ron; Lykken, Joseph; Maeshima, Kaori; Marraffino, John Michael; Mason, David; McBride, Patricia; Miao, Ting; Mishra, Kalanand; Mrenna, Stephen; Musienko, Yuri; Newman-Holmes, Catherine; O'Dell, Vivian; Pivarski, James; Pordes, Ruth; Prokofyev, Oleg; Sexton-Kennedy, Elizabeth; Sharma, Seema; Spalding, William J; Spiegel, Leonard; Tan, Ping; Taylor, Lucas; Tkaczyk, Slawek; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vidal, Richard; Whitmore, Juliana; Wu, Weimin; Yang, Fan; Yumiceva, Francisco; Yun, Jae Chul; Acosta, Darin; Avery, Paul; Bourilkov, Dimitri; Chen, Mingshui; Das, Souvik; De Gruttola, Michele; Di Giovanni, Gian Piero; Dobur, Didar; Drozdetskiy, Alexey; Field, Richard D; Fisher, Matthew; Fu, Yu; Furic, Ivan-Kresimir; Gartner, Joseph; Goldberg, Sean; Hugon, Justin; Kim, Bockjoo; Konigsberg, Jacobo; Korytov, Andrey; Kropivnitskaya, Anna; Kypreos, Theodore; Low, Jia Fu; Matchev, Konstantin; Mitselmakher, Guenakh; Muniz, Lana; Myeonghun, Park; Prescott, Craig; Remington, Ronald; Rinkevicius, Aurelijus; Schmitt, Michael Houston; Scurlock, Bobby; Sellers, Paul; Skhirtladze, Nikoloz; Snowball, Matthew; Wang, Dayong; Yelton, John; Zakaria, Mohammed; Gaultney, Vanessa; Lebolo, Luis Miguel; Linn, Stephan; Markowitz, Pete; Martinez, German; Rodriguez, Jorge Luis; Adams, Todd; Askew, Andrew; Bochenek, Joseph; Chen, Jie; Diamond, Brendan; Gleyzer, Sergei V; Haas, Jeff; Hagopian, Sharon; Hagopian, Vasken; Jenkins, Merrill; Johnson, Kurtis F; Prosper, Harrison; Sekmen, Sezen; Veeraraghavan, Venkatesh; Baarmand, Marc M; Dorney, Brian; Hohlmann, Marcus; Kalakhety, Himali; Vodopiyanov, Igor; Adams, Mark Raymond; Anghel, Ioana Maria; Apanasevich, Leonard; Bai, Yuting; Bazterra, Victor Eduardo; Betts, Russell Richard; Callner, Jeremy; Cavanaugh, Richard; Dragoiu, Cosmin; Gauthier, Lucie; Gerber, Cecilia Elena; Hofman, David Jonathan; Khalatyan, Samvel; Kunde, Gerd J; Lacroix, Florent; Malek, Magdalena; O'Brien, Christine; Silkworth, Christopher; Silvestre, Catherine; Smoron, Agata; Strom, Derek; Varelas, Nikos; Akgun, Ugur; Albayrak, Elif Asli; Bilki, Burak; Clarida, Warren; Duru, Firdevs; Lae, Chung Khim; McCliment, Edward; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Newsom, Charles Ray; Norbeck, Edwin; Olson, Jonathan; Onel, Yasar; Ozok, Ferhat; Sen, Sercan; Wetzel, James; Yetkin, Taylan; Yi, Kai; Barnett, Bruce Arnold; Blumenfeld, Barry; Bonato, Alessio; Eskew, Christopher; Fehling, David; Giurgiu, Gavril; Gritsan, Andrei; Guo, Zijin; Hu, Guofan; Maksimovic, Petar; Rappoccio, Salvatore; Swartz, Morris; Tran, Nhan Viet; Whitbeck, Andrew; Baringer, Philip; Bean, Alice; Benelli, Gabriele; Grachov, Oleg; Kenny Iii, Raymond Patrick; Murray, Michael; Noonan, Daniel; Sanders, Stephen; Wood, Jeffrey Scott; Zhukova, Victoria; Barfuss, Anne-fleur; Bolton, Tim; Chakaberia, Irakli; Ivanov, Andrew; Khalil, Sadia; Makouski, Mikhail; Maravin, Yurii; Shrestha, Shruti; Svintradze, Irakli; Wan, Zongru; Gronberg, Jeffrey; Lange, David; Wright, Douglas; Baden, Drew; Boutemeur, Madjid; Eno, Sarah Catherine; Ferencek, Dinko; Gomez, Jaime; Hadley, Nicholas John; Kellogg, Richard G; Kirn, Malina; Lu, Ying; Mignerey, Alice; Rossato, Kenneth; Rumerio, Paolo; Santanastasio, Francesco; Skuja, Andris; Temple, Jeffrey; Tonjes, Marguerite; Tonwar, Suresh C; Twedt, Elizabeth; 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2011-01-01

A measurement of the differential cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 36 inverse picobarns recorded by the CMS detector at the LHC. The measurement covers the pseudorapidity range |eta|<2.5 and the transverse energy range 25 < ET < 400 GeV, corresponding to the kinematic region 0.007 < xT < 0.114. Photon candidates are identified with two complementary methods, one based on photon conversions in the silicon tracker and the other on isolated energy deposits in the electromagnetic calorimeter. The measured cross section is presented as a function of ET in four pseudorapidity regions. The next-to-leading-order perturbative QCD calculations are consistent with the measured cross section.

Direct measurements of neutral density depletion by two-photon absorption laser-induced fluorescence spectroscopy

International Nuclear Information System (INIS)

Aanesland, A.; Liard, L.; Leray, G.; Jolly, J.; Chabert, P.

2007-01-01

The ground state density of xenon atoms has been measured by spatially resolved laser-induced fluorescence spectroscopy with two-photon excitation in the diffusion chamber of a magnetized Helicon plasma. This technique allows the authors to directly measure the relative variations of the xenon atom density without any assumptions. A significant neutral gas density depletion was measured in the core of the magnetized plasma, in agreement with previous theoretical and experimental works. It was also found that the neutral gas density was depleted near the radial walls

Measurement of the differential cross section for inclusive isolated photon and photon+jets production in proton-proton collisions at $\\sqrt{s} = 13~\\mathrm{TeV}$

CERN Document Server

CMS Collaboration

2018-01-01

Measurements of inclusive isolated photon and photon+jets production in proton-proton collisions at $\\sqrt{s} = 13~\\mathrm{TeV}$ are presented. The analysis uses data collected by the CMS experiment in 2015, corresponding to an integrated luminosity of $2.26~\\mathrm{fb^{-1}}$. The cross section for inclusive isolated photon production is measured as a function of the photon transverse momentum and rapidity. The cross section for photon+jets production is measured as a function of the photon transverse momentum, the photon rapidity, and the rapidity of the jet with the highest transverse momentum. The experimental measurements are found to be in agreement with recent theoretical predictions.

Consumption of organic diets does not affect intake and absorption of zinc and copper in men-evidence from two cross-over trials

DEFF Research Database (Denmark)

Mark, Alicja Budek; Kápolna, Emese; Laursen, Kristian H.

2013-01-01

diets on intake and absorption of zinc and copper in men. Two double-blinded, cross-over, intervention trials (3 dietary periods of 12 days with 2-week-long wash-out) were performed in 2008 (n = 17) and 2009 (n = 16) in young men. The diets were based on 9 crops grown in rigidly controlled organic......Agricultural methods may affect the nutritional composition of plants and cause complex changes in the food matrix. Whether this affects the dietary absorption of minerals that are important for maintaining health thorough life remains unclear. We compared the effects of organic and conventional......; 12.35 ± 0.47 mg per 10 MJ and 44.6% ± 12.1, respectively) and copper (overall mean ± SD; 2.12 ± 0.28 mg per 10 MJ and 41.2% ± 13.2, respectively) were not different between the organic and conventional diets. The growing season had no effect on zinc intake and absorption, but the copper intake...

Experimental Studies of the Mechanism of Photon Absorption on Light Nuclei

International Nuclear Information System (INIS)

Steven Morrow

2000-01-01

A measurement of the reaction 12 C(γ,pγ(prime)) has been made with tagged photons in the range 49.47 γ - , 1/2 + , 5/2 + ) at E ex ≅ 7 MeV in the residual nucleus 11 B, following the reaction 12 C(γ,p), has been made by directly resolving their de-excitation γ-ray decay to the ground state of 11 B. This measurement constitutes the highest resolution ever achieved in determining the excitation function of the residual nucleus after a (γ,p) reaction (∼ 48 keV FWHM at E ex ≅ 7 MeV). Comparison has been made with the data of Kuzin et al, who also measured the relative populations with a resolution of ∼ 270 keV at E ex ≅ 7 MeV. The 7/2 - state at 6.74 MeV has been observed to be the most strongly excited state of the triplet in agreement with Kuzin et al. Disagreement has been found for the relative strengths of the 1/2 + and 5/2 + states in the triplet. An estimation of the maximum effect of angular correlations between the ejected proton and de-excitation γ-ray has been included in the analysis. This effect increases the disagreement between the measurements. A study of the reaction 12 C(e,e(prime)p) has been made in the missing momentum region 260 m L and W T . The experimental data have been compared with Complete Distorted Wave Impulse Approximation calculations and Random Phase Approximation calculations. The latter when including virtual photon absorption on 2-body currents (Meson Exchange Currents + Isobar Currents) are seen to describe the reduced cross sections better than 1-body current or Complete Distorted Wave Impulse Approximation calculations. For the 1st time a comparison between the 12 C(γ,p) reaction and the transverse part of 12 C(e,e(prime)p) reaction cross section has been made. This comparison suggests that the mechanism of the 2 reactions converge when both are studied in equivalent kinematics resolving the long standing issue of anomalous excitation of the ∼ 7 MeV triplet in 11 B, following 12 C(γ,p), not seen in the 12 C

Absorption spectrum of a two-level atom in a bad cavity with injected squeezed vacuum

Science.gov (United States)

Zhou, Peng; Swain, S.

1996-02-01

We study the absorption spectrum of a coherently driven two-level atom interacting with a resonant cavity mode which is coupled to a broadband squeezed vacuum through its input-output mirror in the bad cavity limit. We study the modification of the two-photon correlation strength of the injected squeezed vacuum inside the cavity, and show that the equations describing probe absorption in the cavity environment are formally identical to these in free space, but with modified parameters describing the squeezed vacuum. The two photon correlations induced by the squeezed vacuum are always weaker than in free space. We pay particular attention to the spectral behaviour at line centre in the region of intermediate trength driving intensities, where anomalous spectral features such as hole-burning and dispersive profiles are displayed. These unusual spectral features are very sensitive to the squeezing phase and the Rabi frequency of the driving field. We also derive the threshold value of the Rabi frequency which gives rise to the transparency of the probe beam at the driving frequency. When the Rabi frequency is less than the threshold value, the probe beam is absorbed, whilst the probe beam is amplified (without population inversion under certain conditions) when the Rabi frequency is larger than this threshold. The anomalous spectral features all take place in the vicinity of the critical point dividing the different dynamical regimes, probe absorption and amplification, of the atomic radiation. The physical origin of the strong amplification without population inversion, and the feasibility of observing it, are discussed.

Non-scanning fiber-optic near-infrared beam led to two-photon optogenetic stimulation in-vivo.

Directory of Open Access Journals (Sweden)

Kamal R Dhakal

Full Text Available Stimulation of specific neurons expressing opsins in a targeted region to manipulate brain function has proved to be a powerful tool in neuroscience. However, the use of visible light for optogenetic stimulation is invasive due to low penetration depth and tissue damage owing to larger absorption and scattering. Here, we report, for the first time, in-depth non-scanning fiber-optic two-photon optogenetic stimulation (FO-TPOS of neurons in-vivo in transgenic mouse models. In order to optimize the deep-brain stimulation strategy, we characterized two-photon activation efficacy at different near-infrared laser parameters. The significantly-enhanced in-depth stimulation efficiency of FO-TPOS as compared to conventional single-photon beam was demonstrated both by experiments and Monte Carlo simulation. The non-scanning FO-TPOS technology will lead to better understanding of the in-vivo neural circuitry because this technology permits more precise and less invasive anatomical delivery of stimulation.

Variation of energy absorption buildup factors with incident photon energy and penetration depth for some commonly used solvents

Energy Technology Data Exchange (ETDEWEB)

Singh, Parjit S. [Department of Physics, Punjabi University, Patiala 147 002 (India)], E-mail: dr_parjit@hotmail.com; Singh, Tejbir [Department of Physics, Lovely Professional University, Phagwara 144 402 (India); Kaur, Paramjeet [IAS and Allied Services Training Centre, Punjabi University, Patiala 147 002 (India)

2008-06-15

G.P. fitting method has been used to compute energy absorption buildup factor of some commonly used solvents such as acetonitrile (C{sub 4}H{sub 3}N), butanol (C{sub 4}H{sub 9}OH), chlorobenzene (C{sub 6}H{sub 5}Cl), diethyl ether (C{sub 4}H{sub 10}O), ethanol (C{sub 2}H{sub 5}OH), methanol (CH{sub 3}OH), propanol (C{sub 3}H{sub 7}OH) and water (H{sub 2}O) for the wide energy range (0.015-15.0 MeV) up to the penetration depth of 10 mean free path. The variation of energy absorption buildup factor with chemical composition as well as incident photon energy for the selected solvents has been studied. It has been observed that the maximum value of energy absorption buildup factors shifts to the slightly higher incident photon energy with the increase in equivalent atomic number of the solvent and the solvent with least equivalent atomic number possesses the maximum value of energy absorption buildup factor.

Low momentum transfer theorem for two photon exchange in lepton hardron scattering

International Nuclear Information System (INIS)

Penarrocha, J.A.; Bernabeu, J.

1981-01-01

The two photon contribution to lepton-hardon scattering is considered. Under the assumptions of Lorentz covarience, gauge invarience, unitarity, and analyticity, we prove a low momentum transfer theorem for the relevant amplitudes. Fixed energy dispersion relations tell us that their nonanalytic part, in the neighbourhood of t = 0, is given by the contribution of the two photon cut in the t-channel. The t-channel absorptive parts are obtained from unitarity. Their calculation has as input the two amplitudes corresponding to Compton scattering on the hadron with a pole contribution, and the continuum controlled at low t by the electromagnetic polarizabilities. By means of the dispersion integral, one proves the expansion k 1 (s)+k 2 (s)√-t+k 3 (s)tlog(-t)+O(t) for the continuum contribution, where k 1 (s) is the only unknown. Explicit expressions are obtained for the pole contribution as M→infinity, where M is the hadron mass, and for the continuum when (-t) 2 , where m is the muon mass and Λ is a characteristic parameter of the hadron structure

Mapping of the atomic hydrogen density in combustion processes at atmospheric pressure by two-photon polarization spectroscopy

International Nuclear Information System (INIS)

Steiger, A.; Gruetzmacher, K.; Steiger, M.; Gonzalo, A.B.; Rosa, M.I. de la

2001-01-01

With laser spectroscopic techniques used so far, quantitative measurements of atomic number densities in flames and other combustion processes at atmospheric pressure yield no satisfying results because high quenching rates remarkably reduce the signal size and the results suffer from large uncertainties. Whereas, two-photon polarization spectroscopy is not limited by quenching, as the polarization signal is a direct measure of the two-photon absorption. This sensitive laser technique with high spatial and temporal resolution has been applied to determine absolute number densities and the kinetic temperatures of atomic hydrogen in flames for the first time. The great potential of this method of measurement comes into its own only in conjunction with laser radiation of highest possible spectral quality, i.e. single-frequency ns-pulses with peak irradiance of up to 1 GW/cm 2 tunable around 243 nm for 1S-2S two-photon transition of atomic hydrogen

Enhanced Emission from Single Isolated Gold Quantum Dots Investigated Using Two-Photon-Excited Fluorescence Near-Field Scanning Optical Microscopy.

Science.gov (United States)

Abeyasinghe, Neranga; Kumar, Santosh; Sun, Kai; Mansfield, John F; Jin, Rongchao; Goodson, Theodore

2016-12-21

New approaches in molecular nanoscopy are greatly desired for interrogation of biological, organic, and inorganic objects with sizes below the diffraction limit. Our current work investigates emergent monolayer-protected gold quantum dots (nanoclusters, NCs) composed of 25 Au atoms by utilizing two-photon-excited fluorescence (TPEF) near-field scanning optical microscopy (NSOM) at single NC concentrations. Here, we demonstrate an approach to synthesize and isolate single NCs on solid glass substrates. Subsequent investigation of the NCs using TPEF NSOM reveals that, even when they are separated by distances of several tens of nanometers, we can excite and interrogate single NCs individually. Interestingly, we observe an enhanced two-photon absorption (TPA) cross section for single Au 25 NCs that can be attributed to few-atom local field effects and to local field-induced microscopic cascading, indicating their potential for use in ultrasensitive sensing, disease diagnostics, cancer cell therapy, and molecular computers. Finally, we report room-temperature aperture-based TPEF NSOM imaging of these NCs for the first time at 30 nm point resolution, which is a ∼5-fold improvement compared to the previous best result for the same technique. This report unveils the unique combination of an unusually large TPA cross section and the high photostability of Au NCs to (non-destructively) investigate stable isolated single NCs using TPEF NSOM. This is the first reported optical study of monolayer-protected single quantum clusters, opening some very promising opportunities in spectroscopy of nanosized objects, bioimaging, ultrasensitive sensing, molecular computers, and high-density data storage.

Possibility of producing the event-ready two-photon polarization entangled state with normal photon detectors

International Nuclear Information System (INIS)

Wang Xiangbin

2003-01-01

We propose a scheme to produce the maximally two-photon polarization entangled state with single-photon sources and the passive linear optics devices. In particular, our scheme only requires the normal photon detectors which distinguish the vacuum and non-vacuum Fock number states. A sophisticated photon detector distinguishing between one-photon state and two-photon state is unnecessary in the scheme

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

Solvent effects on the fluorescence and effective three-photon absorption of a Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin

Science.gov (United States)

Wan, Yong; Xue, Yuxiong; Sheng, Ning; Rui, Guanghao; Lv, Changgui; He, Jun; Gu, Bing; Cui, Yiping

2018-06-01

The fluorescence and effective three-photon absorption (3PA) properties of Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin] (labeled Zn(II)-porphyrin) dissolved in three different polar solvents were systematically investigated. The electrochemical and photophysical properties of Zn(II)-porphyrin were investigated by 1H NMR spectra, IR spectra, mass spectroscopy, and electronic absorption spectra. The fluorescence emission of Zn(II)-porphyrin in three different solvents excited at the wavelengths of 420 nm (Soret band) and 550 nm (Q-band) were analyzed. By performing Z-scan experiments with femtosecond laser pulses at a wavelength of 800 nm, the effective 3PA process of Zn(II)-porphyrin in three different solvents was observed and the underlying mechanism was discussed in detail. It is found that the fluorescence spectra slightly depend on the polarity of the solvent. Interestingly, the effective 3PA properties of Zn(II)-porphyrin strongly depend on the solvent polarity. The lower the solvent polarity is, the larger effective 3PA cross-section is. Low polar solvents are beneficial to applications of Zn(II)-porphyrin in optical limiting, photodynamic therapy, etc.

Two-Dimentional Photonic Crystal Waveguides

DEFF Research Database (Denmark)

Søndergaard, Thomas; Dridi, Kim

1999-01-01

possible a novel class of optical microcavities, whereas line defects make possible a novel class of waveguides. In this paper we will analyze two-dimensional photonic crystal waveguides based on photonic crystals with rods arranged on a triangular and a square lattice using a plane-wave expansion method......In the recent years a new class of periodic high-index contrast dielectric structures, known as photonic bandgap structures, has been discovered. In these structures frequency intervals, known as photonic bandgaps, where propagation of electromagnetic waves is not allowed, exist due to the periodic...... dielectric function. This is analogous to semiconductors, where electronic bandgaps exist due to the periodic arrangement of atoms. As is also the case for semiconductor structures, photonic bandgap structures may become of even greater value when defects are introduced. In particular, point defects make...

Two photon production of charm states - a charmonium calculation

International Nuclear Information System (INIS)

Suaya, R.

1980-03-01

The comparison of the nonrelativistic multichannel calculation with the double Rutherford process shows that duality is satisfied, in the sense that if one averages the actual cross sections for a wide enough range of W one gets the same result as for nonstrongly interacting point like quarks. It has been shown for the case of e + e - annihilation that duality in this sense follows from nonrelativistic potential models; and it has been verified that this proof can be extended to two-photon processes

Quarkonium two-photon decays in QCD

International Nuclear Information System (INIS)

Dulyan, L.S.; Khodjamirian, A.Yu.; Magakian, A.D.

1989-01-01

The two-photon decay of tensor charmonium χ c2 → 2 γ is calculated with account of gluon condensate effects. The result is in good agreement with experiment. The two-photon width of pseudoscalar b-quarkonium η b → 2 γ is estimated. 19 refs.; 1 fig.; 1 tab

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

Analysis of the intermediate-band absorption properties of type-II GaSb/GaAs quantum-dot photovoltaics

Science.gov (United States)

Ramiro, I.; Villa, J.; Tablero, C.; Antolín, E.; Luque, A.; Martí, A.; Hwang, J.; Phillips, J.; Martin, A. J.; Millunchick, J.

2017-09-01

Quantum-dot (QD) intermediate-band (IB) materials are regarded as promising candidates for high-efficiency photovoltaics. The sequential two-step two-photon absorption processes that take place in these materials have been proposed to develop high-efficiency solar cells and infrared (IR) photodetectors. In this work, we experimentally and theoretically study the interrelation of the absorptivity with transitions of carriers to and from the IB in type-II GaSb/GaAs QD devices. Our devices exhibit three optical band gaps with: EL=0.49 eV ,EH=1.02 eV , and EG=1.52 eV , with the IB located 0.49 eV above the valence band. These values are well supported by semiempirical calculations of the QDs electronic structure. Through intensity-dependent two-photon photocurrent experiments, we are able to vary the filling state of the IB, thus modifying the absorptivity of the transitions to and from this band. By filling the IB with holes via E =1.32 eV or E =1.93 eV monochromatic illumination, we demonstrate an increase in the EL-related absorptivity of more than two orders of magnitude and a decrease in the EH-related absorptivity of one order of magnitude. The antisymmetrical evolution of those absorptivities is quantitatively explained by a photoinduced shift of the quasi-Fermi level of the IB. Furthermore, we report the observation of a two-photon photovoltage, i.e., the contribution of subband gap two-photon absorption to increase the open-circuit voltage of solar cells. We find that the generation of the two-photon photovoltage is related, in general, to the production of a two-photon photocurrent. However, while photons with energy close to EL participate in the production of the two-photon photocurrent, they are not effective in the production of a two-photon photovoltage. We also report the responsivity of GaSb/GaAs QD devices performing as optically triggered photodetectors. These devices exhibit an amplification factor of almost 400 in the IR spectral region. This high

Transepithelial Riboflavin Absorption in an Ex Vivo Rabbit Corneal Model.

Science.gov (United States)

Gore, Daniel M; O'Brart, David; French, Paul; Dunsby, Chris; Allan, Bruce D

2015-07-01

To measure depth-specific riboflavin concentrations in corneal stroma using two-photon fluorescence microscopy and compare commercially available transepithelial corneal collagen cross-linking (CXL) protocols. Transepithelial CXL riboflavin preparations--MedioCross TE, Ribocross TE, Paracel plus VibeX Xtra, and iontophoresis with Ricrolin+--were applied to the corneal surface of fresh postmortem rabbit eyes in accordance with manufacturers' recommendations for clinical use. Riboflavin 0.1% (VibeX Rapid) was applied after corneal epithelial debridement as a positive control. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35-μm thick were cut on a cryostat, mounted on a slide, and imaged by two-photon fluorescence microscopy. Mean (SD) concentrations were calculated from five globes tested for each protocol. Peak riboflavin concentration of 0.09% (± 0.01) was observed within the most superficial stroma (stromal depth 0-10 μm) in positive controls (epithelium-off). At the same depth, peak stromal riboflavin concentrations for MedioCross TE, Ricrolin+, Paracel/Xtra, and Ribocross TE were 0.054% (± 0.01), 0.031% (0.003), 0.021% (± 0.001), and 0.015% (± 0.004), respectively. At a depth of 300 μm (within the demarcation zone commonly seen after corneal cross-linking), the stromal concentration in epithelium-off positive controls was 0.075% (± 0.006), while at the same depth MedioCross TE and Ricrolin+ achieved 0.018% (± 0.006) and 0.016% (0.002), respectively. None of the remaining transepithelial protocols achieved concentrations above 0.005% at this same 300-μm depth. Overall, MedioCross TE was the best-performing transepithelial formulation. Corneal epithelium is a significant barrier to riboflavin absorption into the stroma. Existing commercial transepithelial CXL protocols achieve relatively low riboflavin concentrations in the anterior corneal stroma when compared to gold standard epithelium-off absorption

VUV-absorption cross section of CO2 at high temperatures and impact on exoplanet atmospheres

Directory of Open Access Journals (Sweden)

Venot Olivia

2014-02-01

Full Text Available Ultraviolet (UV absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO2 is very sensitive to temperature, especially above 160 nm. Within the studied range of temperature, the CO2 cross section can vary by more than two orders of magnitude. This, in particular, makes the absorption of CO2 significant up to wavelengths as high as 230 nm, while it is negligible above 200 nm at 300 K. To investigate the influence of these new data on the photochemistry of exoplanets, we implemented the measured cross section into a 1D photochemical model. The model predicts that accounting for this temperature dependency of CO2 cross section can affect the computed abundances of NH3, CO2, and CO by one order of magnitude in the atmospheres of hot Jupiter and hot Neptune.

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.)

Measurement of photon production cross sections with the ATLAS detector

CERN Document Server

Turra, Ruggero; The ATLAS collaboration

2017-01-01

The production of prompt isolated photons at hadron colliders provides a stringent test of perturbative QCD and can be used to probe the proton structure. The ATLAS Collaboration has performed precise measurements of the inclusive production of isolated prompt photons at a centre-of-mass energy of 13 TeV, differential in both rapidity and photon transverse momentum. In addition, the integrated and differential cross sections for isolated photon pairs at 8 TeV have been measured. The results are compared with state-of-the-art theory predictions at NLO in QCD and with predictions of several MC generators. The production of prompt photons in association with jets provides an additional testing ground for perturbative QCD (pQCD) with a hard colourless probe less affected by hadronisation effects than jet production. The dynamics of isolated-photon plus jet production in pp collisions at a centre-of-mass energy of 8 and 13 TeV will be presented and discussed.

The thermal neutron absorption cross-sections, resonance integrals and resonance parameters of silicon and its stable isotopes

International Nuclear Information System (INIS)

Story, J.S.

1969-09-01

The data available up to the end of November 1968 on the thermal neutron absorption cross-sections, resonance absorption integrals, and resonance parameters of silicon and its stable isotopes are collected and discussed. Estimates are given of the mean spacing of the energy levels of the compound nuclei near the neutron binding energy. It is concluded that the thermal neutron absorption cross-section and resonance absorption integral of natural silicon are not well established. The data on these two parameters are somewhat correlated, and three different assessments of the resonance integral are presented which differ over-all by a factor of 230. Many resonances have been detected by charged particle reactions which have not yet been observed in neutron cross-section measurements. One of these resonances of Si 2 8, at E n = 4 ± 5 keV might account for the large resonance integral which is derived, very uncertainly, from integral data. The principal source of the measured resonance integral of Si 3 0 has not yet been located. The thermal neutron absorption cross-section of Si 2 8 appears to result mainly from a negative energy resonance, possibly the resonance at E n = - 59 ± 5 keV detected by the Si 2 8 (d,p) reaction. (author)

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.

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

Coherence revivals in two-photon frequency combs

International Nuclear Information System (INIS)

Torres-Company, Victor; Lancis, Jesus; Lajunen, Hanna; Friberg, Ari T.

2011-01-01

We describe and theoretically analyze the self-imaging Talbot effect of entangled photon pairs in the time domain. Rich phenomena are observed in coherence propagation along dispersive media of mode-locked two-photon states with frequency entanglement exhibiting a comblike correlation function. Our results can be used to remotely transfer frequency standards through optical fiber networks with two-photon light, avoiding the requirement of dispersion compensation.

Measurement of doubly differential collision cross-sections for double-photon Compton scattering of 0.662 MeV gamma rays

International Nuclear Information System (INIS)

Datta, Gulshan; Saddi, M.B.; Singh, B.; Sandhu, B.S.

2007-01-01

The doubly differential collision cross-sections of the double-photon Compton process have been measured experimentally for 0.662 MeV incident gamma photons. The measurements are carried out using a single gamma detector, a technique avoiding the use of the complicated slow-fast coincidence set-up used till now for observing this higher order QED process. The energy spectra of detected photons are observed as a long tail to the single-photon Compton line on the lower side of the full energy peak in the recorded scattered energy spectrum. The measured values of the cross-section for different independent energy levels of one of the two final photons are of the same magnitude but show deviation from the corresponding values obtained from the theory. However, the present measurements are first of its kind and in view of the nature and order of deviations, the agreement of measured values with theory is quite satisfactory

PHOBINS: an index file of photon production cross section data and its utility code system

International Nuclear Information System (INIS)

Hasegawa, Akira; Koyama, Kinji; Ido, Masaru; Hotta, Masakazu; Miyasaka, Shun-ichi

1978-08-01

The code System PHOBINS developed for reference of photon production cross sections is described in detail. The system is intended to grasp the present status of photon production data and present the information of available data. It consists of four utility routines, CREA, UP-DT, REF and BACK, and data files. These utility routines are used for making an index file of the photon production cross sections, updating the index file, searching the index file and producing a back-up file of the index file. In the index file of the photon production cross sections, a data base system is employed for efficient data management in economical storage, ease of updating and efficient reference. The present report is a reference manual of PHOBINS. (author)

On the validity of the equivalent-photon approximation for virtual photon-photon collisions

International Nuclear Information System (INIS)

Carimalo, C.; Kessler, P.; Parisi, J.

1979-05-01

For virtual photon-photon collisions in electron storage rings, one derive the equivalent-photon approximation from a helicity treatment, and present it in two forms, involving respectively (i) polarized transverse photons ('transverse-photon approximation') and (ii) unpolarized ones ('Williams-Weizsaecker approximation'). One first postulates the conditions of validity of the approximation on the basis of analytic considerations, and then check them numerically in the case of the process e e → e e μ + μ - . For this check, we consider the completely differentiated cross section as far as approximation (i) is concerned; and in the case of approximation (ii), the cross section differentiated with respect to all variables except the azimuthal angles. The results are given in the form of Tables showing the lower and higher limit of the error involved in the approximation for a large variety of kinematic configurations (i. e., energy losses and scattering angles of both electrons). Those Tables are discussed in detail, and conclusions are drawn as to the applicability of the equivalent-photon approximation to future experiments to be performed with high-energy electron storage rings

Energy dependence of effective atomic numbers for photon energy absorption and photon interaction: Studies of some biological molecules in the energy range 1 keV-20 MeV