WorldWideScience

Sample records for atomic fluorescence spectroscopy

  1. Studies in atomic-fluorescence spectroscopy-V The fluorescence characteristics and determination of antimony.

    Science.gov (United States)

    Dagnall, R M; Thompson, K C; West, T S

    1967-10-01

    Atomic-fluorescence of antimony may be generated in an air-propane flame by nebulizing aqueous solutions of antimony salts whilst irradiating the flame by means of a microwave-excited electrode-less discharge tube operating at 30 W. The strongest fluorescence is exhibited by the (4)S(11 2 ) --> (4)P(1 3 ) 2311 A resonance line and weaker signals are observed at the 2068 and 2176 A resonance lines and at four intercombination lines, at 2598, 2671, 2770 and 2878 A. A process of thermally assisted direct-line fluorescence is postulated to account for the otherwise inexplicable intensity of the 2598 A line emission. Atomic-fluorescence spectroscopy at 2176 A permits the determination of antimony in the range 0.1-120 ppm with a detection limit of 0.05 ppm. With the same equipment and source, the range of measurement for atomic-absorption was 6-120 ppm and the detection limit was 1 ppm. No interferences were observed from 100-fold molar amounts of Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, NH(4), Pb and Zn or from arsenate, chloride, nitrate, phosphate and sulphate. PMID:18960212

  2. Laser-excitation atomic fluorescence spectroscopy in a helium microwave-induced plasma

    Science.gov (United States)

    Schroeder, Timothy S.

    The focus of this dissertation is to report the first documented coupling of helium microwave induced plasmas (MIPs) to laser excitation atomic fluorescence spectroscopy. The ability to effectively produce intense atomic emission from both metal and nonmetal analytes gives helium microwave induced plasmas a greater flexibility than the more commonly utilized argon inductively coupled plasma (ICP). Originally designed as an element selective detector for non-aqueous chromatography applications at low applied powers (plasma has been applied to aqueous sample determinations at higher applied powers (>500 W). The helium MIP has been shown to be a very powerful analytical atomic spectroscopy tool. The development of the pulsed dye laser offered an improved method of excitation in the field of atomic fluorescence. The use of laser excitation for atomic fluorescence was a logical successor to the conventional excitation methods involving hollow cathode lamps and continuum sources. The highly intense, directional, and monochromatic nature of laser radiation results in an increased population of atomic species in excited electronic states where atomic fluorescence can occur. The application of laser excitation atomic fluorescence to the analysis of metals in a helium microwave induced plasma with ultrasonic sample nebulization was the initial focus of this work. Experimental conditions and results are included for the aqueous characterization of manganese, lead, thallium, and iron in the helium MIP- LEAFS system. These results are compared to previous laser excitation atomic fluorescence experimentation. The effect of matrix interferences on the analytical fluorescence signal was also investigated for each element. The advantage of helium MIPs over argon ICPs in the determination of nonmetals in solution indicates that the helium MIP is an excellent candidate for laser excitation atomic fluorescence experiments involving nonmetals such as chlorine, bromine, iodine, and

  3. Laser-induced atomic fragment fluorescence spectroscopy: a facile technique for molecular spectroscopy of spin-forbidden states.

    Science.gov (United States)

    Zhang, Qun; Chen, Yang; Keil, Mark

    2009-03-01

    Spectra of spin-forbidden and spin-allowed transitions in the mixed b (3)Pi(u) approximately A (1)Sigma(u)(+) state of Na(2) are measured separately by two-photon excitation using a single tunable dye laser. The two-photon excitation produces Na(*)(3p) by photodissociation, which is easily and sensitively detected by atomic fluorescence. At low laser power, only the A (1)Sigma(u)(+) state is excited, completely free of triplet excitation. At high laser power, photodissociation via the intermediate b (3)Pi(u) triplet state becomes much more likely, effectively "switching" the observations from singlet spectroscopy to triplet spectroscopy with only minor apparatus changes. This technique of perturbation-assisted laser-induced atomic fragment fluorescence may therefore be especially useful as a general vehicle for investigating perturbation-related physics pertinent to the spin-forbidden states, as well as for studying allowed and forbidden states of other molecules.

  4. Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

    International Nuclear Information System (INIS)

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g7/2 5/2[413] neutron and g9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)

  5. Time-resolved fluorescence spectroscopy of matrix-isolated silver atoms after pulsed excitation of inner-shell transitions

    Science.gov (United States)

    Hebert, T.; Wiggenhauser, H.; Schriever, U.; Kolb, D. M.

    1990-02-01

    The energy dissipation in matrix-isolated silver atoms after pulsed vacuum ultraviolet (VUV) excitation of 4d-5p transitions has been studied by time-resolved fluorescence spectroscopy. The decay behavior of the various fluorescence bands has been analyzed and a model for the relaxation process proposed within the framework of a two-dimensional configuration-coordinate diagram. If minute quantities of Ag2 are present in the matrix, the analysis requires consideration of energy transfer between silver atoms and dimers.

  6. New Homogeneous Standards by Atomic Layer Deposition for Synchrotron X-ray Fluorescence and Absorption Spectroscopies.

    Energy Technology Data Exchange (ETDEWEB)

    Butterworth, A.L.; Becker, N.; Gainsforth, Z.; Lanzirotti, A.; Newville, M.; Proslier, T.; Stodolna, J.; Sutton, S.; Tyliszczak, T.; Westphal, A.J.; Zasadzinski, J. (UCB)

    2012-03-13

    Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and characterizing them using multiple analytical methods, including ellipsometry, Rutherford Back Scattering at Evans Analytical, Synchrotron X-ray Fluorescence (SXRF) at Advanced Photon Source (APS) Beamline 13-ID, Synchrotron X-ray Absorption Spectroscopy (XAS) at Advanced Light Source (ALS) Beamlines 11.0.2 and 5.3.2.1 and by electron microscopy techniques. Our motivation for developing much-needed cross-calibration of synchrotron techniques is borne from coordinated analyses of particles captured in the aerogel of the NASA Stardust Interstellar Dust Collector (SIDC). The Stardust Interstellar Dust Preliminary Examination (ISPE) team have characterized three sub-nanogram, {approx}1{micro}m-sized fragments considered as candidates to be the first contemporary interstellar dust ever collected, based on their chemistries and trajectories. The candidates were analyzed in small wedges of aerogel in which they were extracted from the larger collector, using high sensitivity, high spatial resolution >3 keV synchrotron x-ray fluorescence spectroscopy (SXRF) and <2 keV synchrotron x-ray transmission microscopy (STXM) during Stardust ISPE. The ISPE synchrotron techniques have complementary capabilities. Hard X-ray SXRF is sensitive to sub-fg mass of elements Z {ge} 20 (calcium) and has a spatial resolution as low as 90nm. X-ray Diffraction data were collected simultaneously with SXRF data. Soft X-ray STXM at ALS beamline 11.0.2 can detect fg-mass of most elements, including cosmochemically important oxygen, magnesium, aluminum and silicon, which are invisible to SXRF in this application. ALS beamline 11.0.2 has spatial resolution

  7. Fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    M.A. Hink

    2015-01-01

    Fluorescence fluctuation spectroscopy techniques allow the quantification of fluorescent molecules present at the nanomolar concentration level. After a brief introduction to the technique, this chapter presents a protocol including background information in order to measure and quantify the molecul

  8. Velocity and electronic state distributions of sputtered Fe atoms by laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Velocity distributions and relative populations in the fine-structure levels of the a5D/sub J/ ground state of Fe atoms, produced by sputtering with 3 keV argon ions, have been investigated by Doppler shifted laser induced fluorescence. The laser system employs a single-mode, scanning ring dye laser, amplified by a sequence of three excimer-pumped flowing-dye cells. Frequency doubling in a KD*P crystal was used to produce high energy (> .5 mJ) pulses of narrowband tunable UV output near 300 nm. Laser power influence on effective velocity bandwidth was investigated. Favorable light-collection geometry minimized distortion of the velocity spectra from apparatus-averaging effects. In impurity flux diagnostic applications in fusion devices, substantial spatial averaging may occur. In the latter case, the narrow velocity bandwidth (70 m/s, transform limit) of the present laser system is particularly useful

  9. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  10. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  11. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1995-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is promarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  12. Fluorescence spectroscopy in the nanosecond range for matrix-isolated Cu atoms and dimers

    Science.gov (United States)

    Wiggenhauser, H.; Kolb, D. M.; Rotermund, H. H.; Schrittenlacher, W.; Schroeder, W.

    1985-11-01

    Synchrotron radiation in the single-bunch mode was employed to study time-resolved emission from Cu atoms and dimers isolated in a Ne matrix. The decay time of the matrix-related emission at 3.5 eV for Cu in Ne after excitation of the 4s → 4p resonance transition was determined as 6.9±0.3 ns, while excitation into higher-lying 3d → 4p transitions resulted in a much slower decay of the 3.5 eV emission. From analysis of rise and decay times, a detailed diagram for energy dissipation in matrix-isolated Cu atoms has been derived. The B → X (Σ u → Σ g) emission of Cu 2 in Ne has a first-order decay time of about 10 ns.

  13. Laser spectroscopy of sputtered atoms

    International Nuclear Information System (INIS)

    The use of laser radiation to study the sputtering process is of relatively recent origin. Much has been learned from this work about the basic physics of the sputtering process itself through measurements of velocity and excited state distributions of sputtered atoms and the effects of adsorbates on substrate sputtering yields. Furthermore, the identification, characterization, and sensitive detection of sputtered atoms by laser spectroscopy has led to the development of in situ diagnostics for impurity fluxes in the plasma edge regions of tokamaks and of ultrasensitive methods (ppB Fe in Si) for surface analysis with ultralow (picocoulomb) ion fluences. The techniques involved in this work, laser fluorescence and multiphoton resonance ionization spectroscopy, will be described and illustrations given of results achieved up to now. 55 refs., 5 figs., 1 tab

  14. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  15. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Electric discharge type atomic vaporizer is developed for the spectroscopic study on actinide elements. Laser induced fluorescence study on actinide elements is performed by using this high temperature type atomizer. For the effective photoionization of elements, copper vapor laser pumped dye laser and electron beam heating type atomic vaporizer are built and their characteristics are measured. In addition, resonance ionization mass spectroscopic analysis for lead sample as well as laser induced fluorescence study on uranium sample in solution phase is made. (Author)

  16. Symposium on atomic spectroscopy

    International Nuclear Information System (INIS)

    Topics covered by the conference include: fast beam spectroscopy; astrophysical and other spectra; highly ionized spectroscopy; complex spectra; rydberg levels; fine structure, hyperfine structure and isotope shift; lineshapes; lifetimes, oscillator strengths and Einstein coefficients; and spectroscopy with lasers. Abstracts of the conference papers are presented

  17. Symposium on atomic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    Topics covered by the conference include: fast beam spectroscopy; astrophysical and other spectra; highly ionized spectroscopy; complex spectra; rydberg levels; fine structure, hyperfine structure and isotope shift; lineshapes; lifetimes, oscillator strengths and Einstein coefficients; and spectroscopy with lasers. Abstracts of the conference papers are presented. (GHT)

  18. Atomic spectroscopy and radiative processes

    CERN Document Server

    Landi Degl'Innocenti, Egidio

    2014-01-01

    This book describes the basic physical principles of atomic spectroscopy and the absorption and emission of radiation in astrophysical and laboratory plasmas. It summarizes the basics of electromagnetism and thermodynamics and then describes in detail the theory of atomic spectra for complex atoms, with emphasis on astrophysical applications. Both equilibrium and non-equilibrium phenomena in plasmas are considered. The interaction between radiation and matter is described, together with various types of radiation (e.g., cyclotron, synchrotron, bremsstrahlung, Compton). The basic theory of polarization is explained, as is the theory of radiative transfer for astrophysical applications. Atomic Spectroscopy and Radiative Processes bridges the gap between basic books on atomic spectroscopy and the very specialized publications for the advanced researcher: it will provide under- and postgraduates with a clear in-depth description of theoretical aspects, supported by practical examples of applications.

  19. Imaging an atomic beam using fluorescence

    Institute of Scientific and Technical Information of China (English)

    Ming He(何明); Jin Wang(王谨); Mingsheng Zhan(詹明生)

    2003-01-01

    A fluorescence detection scheme is applied to image an atomic beam. Using two laser diodes as the sources of detection light and pumping light respectively, the fluorescence image of the atomic beam is then observed by a commercial CCD-camera, which is corresponding to the atomic state and velocity distribution. The detection scheme has a great utilization in the experiments of cold atoms and atomic optics.

  20. Decoherence Spectroscopy for Atom Interferometry

    Directory of Open Access Journals (Sweden)

    Raisa Trubko

    2016-08-01

    Full Text Available Decoherence due to photon scattering in an atom interferometer was studied as a function of laser frequency near an atomic resonance. The resulting decoherence (contrast-loss spectra will be used to calibrate measurements of tune-out wavelengths that are made with the same apparatus. To support this goal, a theoretical model of decoherence spectroscopy is presented here along with experimental tests of this model.

  1. Fluorescence spectroscopy: basic foundations and methods

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...

  2. Fluorescence fluctuation spectroscopy (FFS), part A

    CERN Document Server

    Tetin, Sergey

    2013-01-01

    This new volume of Methods in Enzymology continues the legacy of this premier serial by containing quality chapters authored by leaders in the field. This volume covers Fluorescence Fluctuation SpectroscopyContains chapters on such topics as Time-integrated fluorescence cumulant analysis, Pulsed Interleaved Excitation, and raster image correlation spectroscopy and number and brightness analysis.Continues the legacy of this premier serial with quality chapters authored by leaders in the fieldCovers fluorescence fluctuation spectroscopyContains chapte

  3. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Laser atomic spectroscopic study on actinium element has been performed in many areas of spectroscopy. The study on characteristic of atomic vapor has been proceeded for copper atom and the spatial density distribution of copper vapor is measured. This experimental data has been compared with the theoretically calculated data. In spectroscopic experiment, the first and second excited states for actinium element are identified and the most efficient ionization scheme for actinium element is identified. In addition, the corrosion problem for filament material due to the heating of the actinium element has been studied. (Author)

  4. CANAS '01 - Colloquium analytical atomic spectroscopy; CANAS '01 - Colloquium Analytische Atomspektroskopie. Programm. Kurzfassungen der Vortraege und Poster

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The main topics of the meeting on analytical atom spectroscopy were: optical atom spectrometry, x-ray fluorescence analysis, absorption spectroscopy, icp mass spectroscopy, trace analysis, sampling, sample preparation and quality assurance.

  5. Studies on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Laser atomic spectroscopy is studied both theoretically and experimentally. For Na-like ions, possible electric dipole, quadrupole and magnetic dipole transitions between atomic levels below 4f doublet F (J=7/2) state are investigated, using the recently developed computer programs - MCDF, MJE and MULTPOL. Line strength, oscillator strength and transition probability are calculated. A preliminary results for Hg-RIS experiment are also presented. Q-switched Nd:YAG laser, high power dye laser, vacuum system, ionization cell and ion measuring system are constructed, and their characteristics are examined. (Author)

  6. Precision Spectroscopy of Atomic Hydrogen

    Science.gov (United States)

    Beyer, A.; Parthey, Ch G.; Kolachevsky, N.; Alnis, J.; Khabarova, K.; Pohl, R.; Peters, E.; Yost, D. C.; Matveev, A.; Predehl, K.; Droste, S.; Wilken, T.; Holzwarth, R.; Hänsch, T. W.; Abgrall, M.; Rovera, D.; Salomon, Ch; Laurent, Ph; Udem, Th

    2013-12-01

    Precise determinations of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state. Its transition frequency has now been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference [1]. A recent measurement of the 2S - 2P3/2 transition frequency in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct [2, 3]. We hope to contribute to this so-called "proton size puzzle" by providing additional experimental input from hydrogen spectroscopy.

  7. Fluorescence spectroscopy of dental calculus

    International Nuclear Information System (INIS)

    The aim of the present study was to investigate the fluorescence properties of dental calculus in comparison with the properties of adjacent unaffected tooth structure using both lasers and LEDs in the UV-visible range for fluorescence excitation. The influence of calculus color on the informative signal is demonstrated. The optimal spectral bands of excitation and registration of the fluorescence are determined

  8. Time-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

  9. Determination of Mercury, Lead and Arsenic in Mainstream Smoke of Cigarette by Atomic Fluorescence Spectroscopy%原子荧光法测定卷烟主流烟气中的汞·砷·铅

    Institute of Scientific and Technical Information of China (English)

    孔维松; 汤丹俞; 曾晓鹰; 者为; 施红林; 张峻松

    2009-01-01

    A new method for the determination of mercury, lead and arsenic in cigarette smoke by using atomic fluorescence spectroscopy was studied.The mainstream cigarette smoke was collected by cambridge filter, and mercury, lead and arsenic were collected with 2% hydrochloric acid ultrasonic leaching filter.The mercury, lead and arsenic in digest were determined by atomic fluorescence spectroscopy.Under the optimum determination conditions, the standard relative standard deviations are 2.8%-3.2% and the recoveries are 91%-95%.%研究了用原子荧光法测定卷烟主流烟气中的汞、砷、铅.结果表明,卷烟主流烟气用剑桥滤片捕集,用2%盐酸超声波浸取滤片上捕集的汞、砷、铅,然后用原子荧光法测定,方法相对标准偏差为2.8%~3.2%,标准回收率为91%~95%.

  10. Fluorescence correlation spectroscopy in laser gradient field

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fluorescence correlation spectroscopy (FCS) is capable of probing dynamic processes in living biological systems. From photon fluctuation of fluorescing particles which diffuse through a small detection volume, FCS reveals information on the concentration and the structure of the particles, as well as information on microscopic environment.In this note, we study the radiation forces experienced by Rayleigh particles in a laser field in details, and analyze the effects of gradient field on FCS measurements.

  11. Fluorescence spectroscopy for neoplasms control

    Science.gov (United States)

    Bratchenko, I. A.; Kristoforova, Yu. A.; Myakinin, O. O.; Artemyev, D. N.; Kozlov, S. V.; Moryatov, A. A.; Zakharov, V. P.

    2016-04-01

    Investigation of malignant skin tumors diagnosis was performed involving two setups for native tissues fluorescence control in visible and near infrared regions. Combined fluorescence analysis for skin malignant melanomas and basal cell carcinomas was performed. Autofluorescence spectra of normal skin and oncological pathologies stimulated by 457 nm and 785 nm lasers were registered for 74 skin tissue samples. Spectra of 10 melanomas and 27 basal cell carcinomas were registered ex vivo. Skin tumors analysis was made on the basis of autofluorescence spectra intensity and curvature for analysis of porphyrins, lipo-pigments, flavins and melanin. Separation of melanomas and basal cell carcinomas was performed on the basis of discriminant analysis. Overall accuracy of basal cell carcinomas and malignant melanomas separation in current study reached 86.5% with 70% sensitivity and 92.6% specificity.

  12. Determination of thiomersal by flow injection coupled with microwave-assisted photochemical online oxidative decomposition of organic mercury and cold vapor atomic fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •Thiomersal was determined on line using FI-MW/UV-CVGAFS. •MW/UV allows a “green” on line oxidation of organic mercury to HgII. •Each measure requires less than 5 min with a LOD of 3 ng mL−1 (as mercury). •Hg concentration in commercial ophthalmic solutions ranges between 7.5 and 59.0 μg mL−1. -- Abstract: We developed a flow injection (FI) method for the determination of thiomersal (sodium ethylmercurithiosalicylate, C9H9HgNaO2S) based on the UV/microwave (MW) photochemical, online oxidation of organic mercury, followed by cold vapor generation atomic fluorescence spectrometry (CVG-AFS) detection. Thiomersal was quantitatively converted in the MW/UV process to Hg(II), with a yield of 97 ± 3%. This reaction was followed by the reduction of Hg(II) to Hg(0) performed in a knotted reaction coil with NaBH4 solution, and AFS detection in an Ar/H2 miniaturized flame. The method was linear in the 0.01–2 μg mL−1 range, with a LOD of 0.003 μg mL−1. This method has been applied to the determination of thiomersal in ophthalmic solutions, with recoveries ranging between 97% and 101%. We found a mercury concentration in commercial ophthalmic solutions ranging between 7.5 and 59.0 μg mL−1

  13. Determination of thiomersal by flow injection coupled with microwave-assisted photochemical online oxidative decomposition of organic mercury and cold vapor atomic fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, Beatrice; Onor, Massimo; Mascherpa, Marco Carlo; D’Ulivo, Alessandro [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Ferrari, Carlo [National Research Council of Italy, C.N.R., Istituto Nazionale di Ottica, INO–UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Bramanti, Emilia, E-mail: bramanti@pi.iccom.cnr.it [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2013-12-04

    Graphical abstract: -- Highlights: •Thiomersal was determined on line using FI-MW/UV-CVGAFS. •MW/UV allows a “green” on line oxidation of organic mercury to Hg{sup II}. •Each measure requires less than 5 min with a LOD of 3 ng mL{sup −1} (as mercury). •Hg concentration in commercial ophthalmic solutions ranges between 7.5 and 59.0 μg mL{sup −1}. -- Abstract: We developed a flow injection (FI) method for the determination of thiomersal (sodium ethylmercurithiosalicylate, C{sub 9}H{sub 9}HgNaO{sub 2}S) based on the UV/microwave (MW) photochemical, online oxidation of organic mercury, followed by cold vapor generation atomic fluorescence spectrometry (CVG-AFS) detection. Thiomersal was quantitatively converted in the MW/UV process to Hg(II), with a yield of 97 ± 3%. This reaction was followed by the reduction of Hg(II) to Hg(0) performed in a knotted reaction coil with NaBH{sub 4} solution, and AFS detection in an Ar/H{sub 2} miniaturized flame. The method was linear in the 0.01–2 μg mL{sup −1} range, with a LOD of 0.003 μg mL{sup −1}. This method has been applied to the determination of thiomersal in ophthalmic solutions, with recoveries ranging between 97% and 101%. We found a mercury concentration in commercial ophthalmic solutions ranging between 7.5 and 59.0 μg mL{sup −1}.

  14. Fluorescence spectroscopy for medical and environmental diagnostics

    International Nuclear Information System (INIS)

    Fluorescence spectroscopy can be used for diagnostics in medical and environmental applications. The many aspects of fluorescence emission are utilized to enhance the accuracy of the diagnosis. A fluorescence detection system, based on nitrogen laser or dye laser excitation and optical multichannel detection, was constructed, and fluorescence spectra from human malignant tumours of various origins, were recorded. Tumour demarcation was observed using exogenous chromophores, as well as the endogenous tissue fluorescence. In particular, δ-amino levulinic acid was found to provide very good tumour demarcation. A multi-colour imaging system capable of simultaneous recording of four fluorescence images at selected wavelengths, was developed. Examples of processed images, based on the four sub-images, are shown for malignant tumours. In addition, data from photodynamic treatment of human malignant tumours are presented. Autofluorescence spectra from excised pieces of human atherosclerotic aorta and atherosclerotic coronary segment were found to be different from those of non-diseased vessels. Furthermore, fluorescence decay curves from atherosclerotic samples were found to differ from those of non-diseased samples. It is concluded that both spectral and temporal information should be utilized to enhance the demarcation. Methods for obtaining fluorescence data free from interference from blood, with applications to in vivo laser angioplasty of atherosclerosis, are discussed. The optical multichannel system and the multi-colour imaging system were integrated with a remote sensing system, originally used for environmental measurements, to obtain fluorescence spectra as well as fluorescence images of plants at a distance of up to 100 m. The fluorescence data from plants subject to environmental stress or senescent plants were found to differ from those obtained from healthy vegetation. 359 refs

  15. Atomic processes relevant to polarization plasma spectroscopy

    International Nuclear Information System (INIS)

    When atoms (ions) are excited anisotropically, polarized excited atoms are produced and the radiation emitted by these atoms is polarized. From the standpoint of plasma spectroscopy research, we review the existing data for various atomic processes that are related to the polarization phenomena. These processes are: electron impact excitation, excitation by atomic and ionic collisions, photoexcitation, radiative recombination and bremsstrahlung. Collisional and radiative relaxation processes of atomic polarization follow. Other topics included are: electric-field measurement, self alignment, Lyman doublet intensity ratio, and magnetic-field measurement of the solar prominence. (author)

  16. Differentiating tissue by fluorescence spectroscopy

    Science.gov (United States)

    Woessner, Stefan; Huen, Julien; Malthan, Dirk

    2004-03-01

    A common problem in several surgical applications is the lack of navigational information. Most often, the only source of information about the location of crucial structures, in relation to the surgical instrument, is the visible and tactile sensory input of the surgeon. In some cases, this leads to time-consuming procedures and a high risk for the patient. Therefore, we developed a spectroscopic sensor system for automatic differentiation between several tissue types. For example in milling processes, a sensor that is able to detect bone in contrast to nerve or vein tissue can be used to control the milling process. We showed exemplarily for the cochlea implant, a typical ENT-surgery, that with the help of our sensor system, the milling of bone can be accelerated without increasing the risk for the patient. It is also possible to use this type of sensor system in the area of medical robotics in soft-tissue applications. With real-time information, a continuous registration can take place, in contrast to a registration that is done using static preoperatively acquired images. We showed that our sensor system can be used to dynamically update the location of the patient in relation to CT or MR-images. In conclusion, we have been able to show that well-known spectroscopy sensors can be used to open new possibilities in medical treatment with and without the use of robotics.

  17. Fluorescence spectroscopy for wastewater monitoring: A review.

    Science.gov (United States)

    Carstea, Elfrida M; Bridgeman, John; Baker, Andy; Reynolds, Darren M

    2016-05-15

    Wastewater quality is usually assessed using physical, chemical and microbiological tests, which are not suitable for online monitoring, provide unreliable results, or use hazardous chemicals. Hence, there is an urgent need to find a rapid and effective method for the evaluation of water quality in natural and engineered systems and for providing an early warning of pollution events. Fluorescence spectroscopy has been shown to be a valuable technique to characterize and monitor wastewater in surface waters for tracking sources of pollution, and in treatment works for process control and optimization. This paper reviews the current progress in applying fluorescence to assess wastewater quality. Studies have shown that, in general, wastewater presents higher fluorescence intensity compared to natural waters for the components associated with peak T (living and dead cellular material and their exudates) and peak C (microbially reprocessed organic matter). Furthermore, peak T fluorescence is significantly reduced after the biological treatment process and peak C is almost completely removed after the chlorination and reverse osmosis stages. Thus, simple fluorometers with appropriate wavelength selectivity, particularly for peaks T and C could be used for online monitoring in wastewater treatment works. This review also shows that care should be taken in any attempt to identify wastewater pollution sources due to potential overlapping fluorophores. Correlations between fluorescence intensity and water quality parameters such as biochemical oxygen demand (BOD) and total organic carbon (TOC) have been developed and dilution of samples, typically up to ×10, has been shown to be useful to limit inner filter effect. It has been concluded that the following research gaps need to be filled: lack of studies on the on-line application of fluorescence spectroscopy in wastewater treatment works and lack of data processing tools suitable for rapid correction and extraction of

  18. Precision spectroscopy of the helium atom

    Institute of Scientific and Technical Information of China (English)

    Shui-ming HU; Zheng-Tian LU; Zong-Chao YAN

    2009-01-01

    Persistent efforts in both theory and experiment have yielded increasingly precise understanding of the helium atom. Because of its simplicity, the helium atom has long been a testing ground for relativistic and quantum electrodynamic effects in few-body atomic systems theoretically and experimentally.Comparison between theory and experiment of the helium spectroscopy in ls2p3pJ can potentially extract a very precise value of the fine structure constant a. The helium atom can also be used to explore exotic nuclear structures. In this paper, we provide a brief review of the recent advances in precision calculations and measurements of the helium atom.

  19. Precision spectroscopy on atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Christian Godehard

    2011-12-15

    This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as {delta}{integral}{sub exp}=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, {delta}{integral}{sub th}=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r{sup 2} right angle {sub d}- left angle r{sup 2} right angle {sub p}=3.82007(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be {integral}{sub 1S-2S}=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10{sup -15}. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of {integral}{sub 1S-2S}=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c{sub (TX)}-0.29c{sub (TY)}-0.08 c{sub (TZ)}=(2.2{+-}1.8) x 10{sup -11} within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level ({partial_derivative})/({partial_derivative}t)ln ({mu}{sub Cs})/({mu}{sub B})=-(3.0{+-}1.2) x 10{sup -15} yr{sup -1}.

  20. Precision spectroscopy on atomic hydrogen

    International Nuclear Information System (INIS)

    This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as Δ∫exp=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, Δ∫th=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r2 right angle d- left angle r2 right angle p=3.82007(65) fm2 and the deuteron structure radius rstr=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be ∫1S-2S=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10-15. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of ∫1S-2S=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c(TX)-0.29c(TY)-0.08 c(TZ)=(2.2±1.8) x 10-11 within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level (∂)/(∂t)ln (μCs)/(μB)=-(3.0±1.2) x 10-15 yr-1.

  1. Two-dimensional fluorescence spectroscopy of laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

    2016-08-01

    We use a two-dimensional laser-induced fluorescence spectroscopy technique to measure the coupled absorption and emission properties of atomic species in plasmas produced via laser ablation of solid aluminum targets at atmospheric pressure. Emission spectra from the Al I 394.4 nm and Al I 396.15 nm transitions are measured while a frequency-doubled, continuous-wave, Ti:Sapphire laser is tuned across the Al I 396.15 nm transition. The resulting two-dimensional spectra show the energy coupling between the two transitions via increased emission intensity for both transitions during resonant absorption of the continuous-wave laser at one transition. Time-delayed and gated detection of the emission spectrum is used to isolate the resonantly-excited fluorescence emission from the thermally-excited emission from the plasma. In addition, the tunable continuous-wave laser measures the absorption spectrum of the Al transition with ultra-high resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing continuous-wave laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods.

  2. Photoelectron spectroscopy of heavy atoms and molecules

    International Nuclear Information System (INIS)

    The importance of relativistic interactions in the photoionization of heavy atoms and molecules has been investigated by the technique of photoelectron spectroscopy. In particular, experiments are reported which illustrate the effects of the spin-orbit interaction in the neutral ground state, final ionic states and continuum states of the photoionization target

  3. Saturation effects in fluorescence correlation spectroscopy

    Science.gov (United States)

    Davis, Lloyd M.; Shen, Guoqing; Ball, David A.

    2005-03-01

    Fluorescence correlation spectroscopy (FCS) could provide a more useful tool for intracellular studies and biological sample characterization if measurement times could be reduced. While an increase in laser power can enable an autocorrelation function (ACF) with adequate signal-to-noise to be acquired within a shorter measurement time, excitation saturation then leads to distortion of the ACF and systematic errors in the measurement results. An empirical method for achieving reduced systematic errors by employing a fitting function with an additional adjustable parameter has been previously introduced for two-photon FCS. Here we provide a unified physical explanation of excitation saturation effects for the three cases of continuous-wave, pulsed one-photon excitation, and two-photon excitation FCS. When the time between laser pulses is longer than the fluorescence lifetime, the signal rate at which excitation saturation occurs is lower for pulsed excitation than for cw excitation, and due to the disparate timescales of the photophysical processes following excitation, it is lower still for two-photon excitation. We use a single-molecule description of FCS to obtain improved analytical ACF fitting functions for the three cases. The fitting functions more accurately account for saturation effects than those previously employed without the need for an additional empirical parameter. Use of these fitting functions removes systematic errors and enables measurements to be acquired more quickly by use of higher laser powers. Increase of background, triplet photophysics, and the cases of scanning FCS and fluorescence cross-correlation spectroscopy are also discussed. Experimental results acquired with a custom built apparatus are presented.

  4. Single molecule detection and fluorescence correlation spectroscopy on surfaces

    OpenAIRE

    Hassler, Kai; Lasser, Theo

    2008-01-01

    In this thesis a new approach for single molecule detection and analysis is explored. This approach is based on the combination of two well established methods, fluorescence correlation spectroscopy (FCS) and total internal reflection fluorescence microscopy (TIRFM). In contrast to most existing fluorescence spectroscopy techniques, the subject of primary interest in FCS is not the fluorescence intensity itself but the random intensity fluctuation around the mean value. Intensity fluctuations...

  5. Single molecule detection and fluorescence correlation spectroscopy on surfaces

    OpenAIRE

    Hassler, Kai

    2006-01-01

    In this thesis a new approach for single molecule detection and analysis is explored. This approach is based on the combination of two well established methods, fluorescence correlation spectroscopy (FCS) and total internal reflection fluorescence microscopy (TIRFM). In contrast to most existing fluorescence spectroscopy techniques, the subject of primary interest in FCS is not the fluorescence intensity itself but the random intensity fluctuation around the mean value. Intensity fluctuations...

  6. APD detectors for biological fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mazeres, S. [Institut de Pharmacologie et de Biologie Structurale, IPBS-CNRS, 205 route de Narbonne 31077 Toulouse Cedex 4 (France)]. E-mail: serge.mazeres@ipbs.fr; Borrel, V. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Magenc, C. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Courrech, J.L. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Bazer-Bachi, R. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France)

    2006-11-01

    Fluorescence spectroscopy is a very convenient and widely used method for studying the molecular background of biological processes [L. Salome, J.L. Cazeil, A. Lopez, J.F. Tocanne, Eur. Biophys. J. 27 (1998) 391-402]. Chromophores are included in the structure under study and a flash of laser light induces fluorescence (Fluorescence Recovery After Photo-bleaching), the decay of which yields information on the polarity, the speed of rotation, and the speed of diffusion as well as on the temporal and spatial evolution of interactions between molecular species. The method can even be used to study living cells [J.F. Tocanne, L. Cezanne, A. Lopez, Prog. Lipid Res. 33 (1994) 203-237, L. Cezanne, A. Lopez, F. Loste, G. Parnaud, O. Saurel, P. Demange, J.F. Tocanne, Biochemistry 38 (1999) 2779-2786]. This is classically performed with a PM-based system. For biological reasons a decrease of the excitation of the cells is highly desirable. Because the fluorescence response then becomes fainter a significant improvement in detector capability would be welcome. We present here results obtained with an Avalanche Photo Diode (APD)-based system. The small sensitive area of detection allows a very significant improvement in signal/noise ratio, improvement in gain, and the opening-up of a new parameter space. With these new detectors we can begin the study of information transmission between cells through morphine receptors. This work involves both electronics engineers and biophysicists, so results and techniques in both fields will be presented here.

  7. Imaging spectroscopy with the atomic force microscope

    OpenAIRE

    Baselt, David R.; Baldeschwieler, John D.

    1994-01-01

    Force curve imaging spectroscopy involves acquiring a force-distance curve at each pixel of an atomic force microscope image. Processing of the resulting data yields images of sample hardness and tip-sample adhesion. These images resemble Z modulation images and the sum of forward and reverse friction images, respectively, and like them exhibit a number of potentially misleading contrast mechanisms. In particular, XY tip motion has a pronounced effect on hardness images and the meniscus force...

  8. Laser Spectroscopy of Antiprotonic Helium Atoms

    CERN Multimedia

    2002-01-01

    %PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

  9. Atoms, molecules and optical physics 1. Atoms and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, Ingolf V.; Schulz, Claus-Peter

    2015-09-01

    This is the first volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 1 provides the canonical knowledge in atomic physics together with basics of modern spectroscopy. Starting from the fundamentals of quantum physics, the reader is familiarized in well structured chapters step by step with the most important phenomena, models and measuring techniques. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

  10. Laser Spectroscopy of Muonic Atoms and Ions

    CERN Document Server

    Pohl, Randolf; Fernandes, Luis M P; Ahmed, Marwan Abdou; Amaro, Fernando D; Amaro, Pedro; Biraben, François; Cardoso, João M R; Covita, Daniel S; Dax, Andreas; Dhawan, Satish; Diepold, Marc; Franke, Beatrice; Galtier, Sandrine; Giesen, Adolf; Gouvea, Andrea L; Götzfried, Johannes; Graf, Thomas; Hänsch, Theodor W; Hildebrandt, Malte; Indelicato, Paul; Julien, Lucile; Kirch, Klaus; Knecht, Andreas; Knowles, Paul; Kottmann, Franz; Krauth, Julian J; Bigot, Eric-Olivier Le; Liu, Yi-Wei; Lopes, José A M; Ludhova, Livia; Machado, Jorge; Monteiro, Cristina M B; Mulhauser, Françoise; Nebel, Tobias; Rabinowitz, Paul; Santos, Joaquim M F dos; Santos, José Paulo; Schaller, Lukas A; Schuhmann, Karsten; Schwob, Catherine; Szabo, Csilla I; Taqqu, David; Veloso, João F C A; Voss, Andreas; Weichelt, Birgit; Antognini, Aldo

    2016-01-01

    Laser spectroscopy of the Lamb shift (2S-2P energy difference) in light muonic atoms or ions, in which one negative muon $\\mu^-$ is bound to a nucleus, has been performed. The measurements yield significantly improved values of the root-mean-square charge radii of the nuclei, owing to the large muon mass, which results in a vastly increased muon wave function overlap with the nucleus. The values of the proton and deuteron radii are 10 and 3 times more accurate than the respective CODATA values, but 7 standard deviations smaller. Data on muonic helium-3 and -4 ions is being analyzed and will give new insights. In future, the (magnetic) Zemach radii of the proton and the helium-3 nuclei will be determined from laser spectroscopy of the 1S hyperfine splittings, and the Lamb shifts of muonic Li, Be and B can be used to improve the respective charge radii.

  11. Collinear laser spectroscopy of atomic cadmium

    OpenAIRE

    Frömmgen, Nadja; Balabanski, Dimiter L.; Bissell, Mark L.; Bieroń, Jacek; Blaum, Klaus; Cheal, Bradley; Flanagan, Kieran; Fritzsche, Stephan; Geppert, Christopher; Hammen, Michael; Kowalska, Magdalena; Kreim, Kim; Krieger, Andreas; Neugart, Rainer; Neyens, Gerda

    2015-01-01

    Hyperfine structure $A$ and $B$ factors of the atomic $5s\\,5p\\,\\; ^3\\rm{P}_2 \\rightarrow 5s\\,6s\\,\\; ^3\\rm{S}_1$ transition are determined from collinear laser spectroscopy data of $^{107-123}$Cd and $^{111m-123m}$Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with $s_{1/2}$ and $d_{5/2}$ nuclear ground states and isomeric $h_{11/2}$ sta...

  12. Single-molecule spectroscopy of fluorescent proteins

    NARCIS (Netherlands)

    Blum, Christian; Subramaniam, Vinod

    2009-01-01

    The discovery and use of fluorescent proteins has revolutionized cellular biology. Despite the widespread use of visible fluorescent proteins as reporters and sensors in cellular environments the versatile photophysics of fluorescent proteins is still subject to intense research. Understanding the d

  13. Atomic spectroscopy sympsoium, Gaithersburg, Maryland, September 23--26, 1975

    International Nuclear Information System (INIS)

    Abstracts of one hundred papers given at the conference are presented along with the conference program and an author index. Session topics include: highly ionized atoms; laser spectroscopy and hyperfine structure; complex spectra; laser spectroscopy, radiation theory; theory of highly ionized atoms and analysis of plasmas; plasma spectroscopy, line strengths; spectral analysis, instrumentation, reference wavelengths; beam foil spectroscopy, line strengths, energy levels; absorption spectroscopy, autoionization, and related theory; and spectral analysis, instrumentation, and VUV physics

  14. Quantification estimate methods for synchrotron radiation X-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bewer, Brian, E-mail: brian.bewer@lightsource.ca

    2015-03-15

    Synchrotron radiation X-ray fluorescence spectroscopy is a method which allows low elemental concentrations to be measured within a sample. To maintain biological or medical relevance increased importance is being placed on quantifying these in situ localized elemental concentrations. For third generation synchrotron light sources, which have the potential for high sample throughput, a rapid method of obtaining a quantification estimate is needed. Non-destructive transmission and surface analysis techniques for first transition metals, or elements of higher atomic number, using reference standards are examined for different sample property regimes to elucidate methods of quantitative synchrotron radiation X-ray fluorescence spectroscopy.

  15. Two-focus fluorescence correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dertinger, T.

    2007-05-15

    Fluorescence Correlation Spectroscopy (FCS) has been invented more than 30 years ago and experienced a renaissance after stable and affordable laser sources and low-noise single-photon detectors have become available. Its ability to measure diffusion coefficients at nanomolar concentrations of analyte made it a widely used tool in biophysics. However, in recent years it has been shown by many authors that aberrational (e.g. astigmatism) and photophysical effects (e.g. optical saturation) may influence the result of an FCS experiment dramatically, so that a precise and reliable estimation of the diffusion coefficient is no longer possible. In this thesis, we report on the development, implementation, and application of a new and robust modification of FCS that we termed two-focus FCS (2fFCS) and which fulfils two requirements: (i) It introduces an external ruler into the measurement by generating two overlapping laser foci of precisely known and fixed distance. (ii) These two foci and corresponding detection regions are generated in such a way that the corresponding molecule detection functions (MDFs) are sufficiently well described by a simple two-parameter model yielding accurate diffusion coefficients when applied to 2fFCS data analysis. Both these properties enable us to measure absolute values of the diffusion coefficient with an accuracy of a few percent. Moreover, it will turn out that the new technique is robust against refractive index mismatch, coverslide thickness deviations, and optical saturation effects, which so often trouble conventional FCS measurements. This thesis deals mainly with the introduction of the new measurement scheme, 2fFCS, but also presents several applications with far-reaching importance. (orig.)

  16. Two-focus fluorescence correlation spectroscopy

    International Nuclear Information System (INIS)

    Fluorescence Correlation Spectroscopy (FCS) has been invented more than 30 years ago and experienced a renaissance after stable and affordable laser sources and low-noise single-photon detectors have become available. Its ability to measure diffusion coefficients at nanomolar concentrations of analyte made it a widely used tool in biophysics. However, in recent years it has been shown by many authors that aberrational (e.g. astigmatism) and photophysical effects (e.g. optical saturation) may influence the result of an FCS experiment dramatically, so that a precise and reliable estimation of the diffusion coefficient is no longer possible. In this thesis, we report on the development, implementation, and application of a new and robust modification of FCS that we termed two-focus FCS (2fFCS) and which fulfils two requirements: (i) It introduces an external ruler into the measurement by generating two overlapping laser foci of precisely known and fixed distance. (ii) These two foci and corresponding detection regions are generated in such a way that the corresponding molecule detection functions (MDFs) are sufficiently well described by a simple two-parameter model yielding accurate diffusion coefficients when applied to 2fFCS data analysis. Both these properties enable us to measure absolute values of the diffusion coefficient with an accuracy of a few percent. Moreover, it will turn out that the new technique is robust against refractive index mismatch, coverslide thickness deviations, and optical saturation effects, which so often trouble conventional FCS measurements. This thesis deals mainly with the introduction of the new measurement scheme, 2fFCS, but also presents several applications with far-reaching importance. (orig.)

  17. Theory of analytical curves in atomic fluorescence flame spectrometry

    NARCIS (Netherlands)

    Hooymayers, H.P.

    1968-01-01

    An explicit expression for the intensity of atomic resonance fluorescence as a function of atomic concentration in a flame is derived under certain idealized conditions. The expression is generally valid for a pure Doppler absorption line profile as well as for a combined Doppler and collisional bro

  18. Quantitative Determination of DNA-Ligand Binding Using Fluorescence Spectroscopy

    Science.gov (United States)

    Healy, Eamonn F.

    2007-01-01

    The effective use of fluorescence spectroscopy for determining the binding of the intercalcating agent crhidium bromide to DNA is being described. The analysis used simple measurement techniques and hence can be easily adopted by the students for a better understanding.

  19. Detection of Counterfeit Tequila by Fluorescence Spectroscopy

    Directory of Open Access Journals (Sweden)

    José Manuel de la Rosa Vázquez

    2015-01-01

    Full Text Available An ultraviolet (UV light induced fluorescence study to discriminate fake tequila from genuine ones is presented. A portable homemade system based on four light emitting diodes (LEDs from 255 to 405 nm and a miniature spectrometer was used. It has been shown that unlike fake and silver tequila, which produce weak fluorescence signal, genuine mixed, rested, and aged tequilas show high fluorescence emission in the range from 400 to 750 nm. The fluorescence intensity grows with aging in 100% agave tequila. Such fluorescence differences can even be observed with naked eyes. The presented results demonstrate that the fluorescence measurement could be a good method to detect counterfeit tequila.

  20. Collinear laser spectroscopy of atomic cadmium

    CERN Document Server

    Frömmgen, Nadja; Bissell, Mark L; Bieroń, Jacek; Blaum, Klaus; Cheal, Bradley; Flanagan, Kieran; Fritzsche, Stephan; Geppert, Christopher; Hammen, Michael; Kowalska, Magdalena; Kreim, Kim; Krieger, Andreas; Neugart, Rainer; Neyens, Gerda; Rajabali, Mustafa M; Nörtershäuser, Wilfried; Papuga, Jasna; Yordanov, Deyan T

    2015-01-01

    Hyperfine structure $A$ and $B$ factors of the atomic $5s\\,5p\\,\\; ^3\\rm{P}_2 \\rightarrow 5s\\,6s\\,\\; ^3\\rm{S}_1$ transition are determined from collinear laser spectroscopy data of $^{107-123}$Cd and $^{111m-123m}$Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with $s_{1/2}$ and $d_{5/2}$ nuclear ground states and isomeric $h_{11/2}$ states is evaluated and a linear relationship is observed for all nuclear states except $s_{1/2}$. This corresponds to the Moskowitz-Lombardi rule that was established in the mercury region of the nuclear chart but in the case of cadmium the slope is distinctively smaller than for mercury. In total four atomic and ionic levels were analyzed and all of them exhibit a similar behaviour. The electric field gradient for the atomic $5s\\,5p\\,\\; ^3\\mathrm{P}_2$ level is derived from multi-configuration Dirac-Hartree-Fock calculatio...

  1. Detection of Counterfeit Tequila by Fluorescence Spectroscopy

    OpenAIRE

    José Manuel de la Rosa Vázquez; Diego Adrián Fabila-Bustos; Luis Felipe de Jesús Quintanar-Hernández; Alma Valor; Suren Stolik

    2015-01-01

    An ultraviolet (UV) light induced fluorescence study to discriminate fake tequila from genuine ones is presented. A portable homemade system based on four light emitting diodes (LEDs) from 255 to 405 nm and a miniature spectrometer was used. It has been shown that unlike fake and silver tequila, which produce weak fluorescence signal, genuine mixed, rested, and aged tequilas show high fluorescence emission in the range from 400 to 750 nm. The fluorescence intensity grows with aging in 100% ag...

  2. Fluorescence spectroscopy and multi-way techniques. PARAFAC

    DEFF Research Database (Denmark)

    Murphy, Kathleen R.; Stedmon, Colin A.; Graeber, Daniel;

    2013-01-01

    of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence...... dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy. © 2013 The Royal Society of Chemistry....

  3. Quantum dots fluorescence quantum yield measured by Thermal Lens Spectroscopy.

    Science.gov (United States)

    Estupiñán-López, Carlos; Dominguez, Christian Tolentino; Cabral Filho, Paulo E; Fontes, Adriana; de Araujo, Renato E

    2014-01-01

    An essential parameter to evaluate the light emission properties of fluorophores is the fluorescence quantum yield, which quantify the conversion efficiency of absorbed photons to emitted photons. We detail here an alternative nonfluorescent method to determine the absolute fluorescence quantum yield of quantum dots (QDs). The method is based in the so-called Thermal Lens Spectroscopy (TLS) technique, which consists on the evaluation of refractive index gradient thermally induced in the fluorescent material by the absorption of light. Aqueous dispersion carboxyl-coated cadmium telluride (CdTe) QDs samples were used to demonstrate the Thermal Lens Spectroscopy technical procedure. PMID:25103802

  4. Fluorescence lifetime standards for time and frequency domain fluorescence spectroscopy

    NARCIS (Netherlands)

    Boens, N.; Qin, Wenwu; Basaric, N.; Hofkens, J.; Ameloot, M.; Pouget, J.; Lefevre, J.P.; Valeur, B.; Gratton, E.; Ven, van de M.; Silva jr., D.; Engelborghs, Y.; Willaert, K.; Sillen, A.; Rumbles, G.; Philips, D.; Visser, A.J.W.G.; Hoek, van A.; Lakowicz, J.R.; Malak, H.; Gryczynski, I.; Szabo, A.G.; Krajcarski, D.T.; Tamai, N.; Miura, A.

    2007-01-01

    A series of fluorophores with single-exponential fluorescence decays in liquid solution at 20 C were measured independently by nine laboratories using single-photon timing and multifrequency phase and modulation fluorometry instruments with lasers as excitation source. The dyes that can serve as flu

  5. Early Amyloidogenic Oligomerization Studied through Fluorescence Lifetime Correlation Spectroscopy

    Directory of Open Access Journals (Sweden)

    Angel Orte

    2012-07-01

    Full Text Available Amyloidogenic protein aggregation is a persistent biomedical problem. Despite active research in disease-related aggregation, the need for multidisciplinary approaches to the problem is evident. Recent advances in single-molecule fluorescence spectroscopy are valuable for examining heterogenic biomolecular systems. In this work, we have explored the initial stages of amyloidogenic aggregation by employing fluorescence lifetime correlation spectroscopy (FLCS, an advanced modification of conventional fluorescence correlation spectroscopy (FCS that utilizes time-resolved information. FLCS provides size distributions and kinetics for the oligomer growth of the SH3 domain of α-spectrin, whose N47A mutant forms amyloid fibrils at pH 3.2 and 37 °C in the presence of salt. The combination of FCS with additional fluorescence lifetime information provides an exciting approach to focus on the initial aggregation stages, allowing a better understanding of the fibrillization process, by providing multidimensional information, valuable in combination with other conventional methodologies.

  6. Study on Atomic Fluorescence Spectrometry Excited by Synchrotron Radiation

    Institute of Scientific and Technical Information of China (English)

    Jia-jia Guo; Wu-er Gan; Guo-bin Zhang; Qing-de Su

    2008-01-01

    A novel analysis approach using atomic fluorescence excited by synchrotron radiation is presented. A system for synchrotron radiation-atomic fluorescence spectrometry is developed, and experimental conditions such as flow rate, analyte acidity, concentration of pre-reducing and hydrogenation system are optimized. The proposed method is successfully applied to get an excitation spectrum of arsenic. Seven of ten primary spectral lines, four of which have never been reported by means of atomic fluorescence spectrometry, agree well with the existing reports. The other three are proposed for the first time. Excitation potentials and possible transitions are investigated. Especially for the prominent line at 234.99 nm, the mechanism of generation is discussed and a model of energy transition processes is proposed.

  7. Elasticity Maps of Living Neurons Measured by Combined Fluorescence and Atomic Force Microscopy

    OpenAIRE

    Spedden, Elise; White, James D.; Naumova, Elena N.; Kaplan, David L.; Staii, Cristian

    2013-01-01

    Detailed knowledge of mechanical parameters such as cell elasticity, stiffness of the growth substrate, or traction stresses generated during axonal extensions is essential for understanding the mechanisms that control neuronal growth. Here, we combine atomic force microscopy-based force spectroscopy with fluorescence microscopy to produce systematic, high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglio...

  8. Assessment of skin flap viability using visible diffuse reflectance spectroscopy and auto-fluorescence spectroscopy

    Science.gov (United States)

    Zhu, Caigang; Chen, Shuo; Chui, Christopher Hoe-Kong; Liu, Quan

    2012-12-01

    The accurate assessment of skin flap viability is vitally important in reconstructive surgery. Early identification of vascular compromise increases the change of successful flap salvage. The ability to determine tissue viability intraoperatively is also extremely useful when the reconstructive surgeon must decide how to inset the flap and whether any tissue must be discarded. Visible diffuse reflectance and auto-fluorescence spectroscopy, which yield different sets of biochemical information, have not been used in the characterization of skin flap viability simultaneously to our best knowledge. We performed both diffuse reflectance and fluorescence measurements on a reverse MacFarlane rat dorsal skin flap model to identify the additional value of auto-fluorescence spectroscopy to the assessment of flap viability. Our result suggests that auto-fluorescence spectroscopy appears to be more sensitive to early biochemical changes in a failed flap than diffuse reflectance spectroscopy, which could be a valuable complement to diffuse reflectance spectroscopy for the assessment of flap viability.

  9. Fluorescence spectra of atomic ensembles in a magneto-optical trap as an optical lattice

    CERN Document Server

    Yoon, Seokchan; Kang, Sungsam; Kim, Wook-Rae; Kim, Jung-Ryul; An, Kyungwon

    2015-01-01

    We present a study on characteristics of a magneto-optical trap (MOT) as an optical lattice. Fluorescence spectra of atoms trapped in a MOT with a passively phase-stabilized beam configuration have been measured by means of the photon-counting heterodyne spectroscopy. We observe a narrow Rayleigh peak and well-resolved Raman sidebands in the fluorescence spectra which clearly show that the MOT itself behaves as a three-dimensional optical lattice. Optical-lattice-like properties of the phase-stabilized MOT such as vibrational frequencies and lineshapes of Rayleigh peak and Raman sidebands are investigated systematically for various trap conditions.

  10. Absorption and fluorescence spectroscopy on a smartphone

    Science.gov (United States)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Ast, Sandra; Rutledge, Peter J.; Jamalipour, Abbas

    2015-07-01

    A self-powered smartphone-based field-portable "dual" spectrometer has been developed for both absorption and fluorescence measurements. The smartphone's existing flash LED has sufficient optical irradiance to undertake absorption measurements within a 3D-printed case containing a low cost nano-imprinted polymer diffraction grating. A UV (λex ~ 370 nm) and VIS (λex ~ 450 nm) LED are wired into the circuit of the flash LED to provide an excitation source for fluorescence measurements. Using a customized app on the smartphone, measurements of absorption and fluorescence spectra are demonstrated using pH-sensitive and Zn2+-responsive probes. Detection over a 300 nm span with 0.42 nm/pixel spectral resolution is demonstrated. Despite the low cost and small size of the portable spectrometer, the results compare well with bench top instruments.

  11. Measurement of DNA size by fluorescence-fluctuation spectroscopy

    International Nuclear Information System (INIS)

    This report covers research on measuring the size of very large DNA molecules by fluorescence-fluctuation spectroscopy. The primary reason was to measure the formation of DNA double-strand breaks in mammalian cells by agents such as ionizing radiation, and to measure the repair of these breaks. Fluorescence-fluctuation spectroscopy was employed because it is known to be able to measure the size of DNA of molecular weight greater than 109 (Weissman, et al., 1976). Most of this report is devoted to the techniques of fluorescent fluctuation spectroscopy. Using the procedures described here, it is likely that measurements could be made of DNA of molecular weight 1010, which would be formed in mammalian cells given 1000 rads of x-rays

  12. Characterizing optical dipole trap via fluorescence of trapped cesium atoms

    Institute of Scientific and Technical Information of China (English)

    LIU; Tao; GENG; Tao; YAN; Shubin; LI; Gang; ZHANG; Jing; WANG; Junmin; PENG; Kunchi; ZHANG; Tiancai

    2006-01-01

    Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.

  13. Mapping of ice cream formulation using fluorescence spectroscopy.

    OpenAIRE

    Granger, Christine; Da Costa, Jean-Pierre; Toutain, Jean; Barey, Philippe; Cansel, Maud

    2006-01-01

    Front-face fluorescence spectroscopy was used to characterize 16 ice cream formulations (four fats, two mono-/diglyceride mixtures, and two protein mixtures). Tryptophan fluorescence spectra were recorded directly from the ice cream samples. The discriminant ability of the data was investigated by principal component analysis (PCA) and partial least square (PLS) discriminant analysis. The similarity maps defined by principal components 1 and 2 allowed clear discrimination between the protein ...

  14. Combined fiber probe for fluorescence lifetime and Raman spectroscopy

    Science.gov (United States)

    Dochow, Sebastian; Ma, Dinglong; Latka, Ines; Bocklitz, Thomas; Hartl, Brad; Bec, Julien; Fatakdawala, Hussain; Marple, Eric; Urmey, Kirk; Wachsmann-Hogiu, Sebastian; Schmitt, Michael; Marcu, Laura; Popp, Jürgen

    2016-01-01

    In this contribution we present a dual modality fiber optic probe combining fluorescence lifetime imaging (FLIm) and Raman spectroscopy for in vivo endoscopic applications. The presented multi-spectroscopy probe enables efficient excitation and collection of fluorescence lifetime signals for FLIm in the UV/visible wavelength region, as well as of Raman spectra in the near-IR for simultaneous Raman/FLIm imaging. The probe was characterized in terms of its lateral resolution and distance dependency of the Raman and FLIm signals. In addition, the feasibility of the probe for in vivo FLIm and Raman spectral characterization of tissue was demonstrated. PMID:26093843

  15. Colorful Polyelectrolytes: An Atom Transfer Radical Polymerization Route to Fluorescent Polystyrene Sulfonate.

    Science.gov (United States)

    Huberty, Wayne; Tong, Xiaowei; Balamurugan, Sreelatha; Deville, Kyle; Russo, Paul S; Zhang, Donghui

    2016-03-01

    A labeled green fluorescent polystyrene sulfonate (LNaPSS) has been synthesized using atom transfer radical polymerization of a styrene sulfonate monomer with a fluorescent co-monomer, fluorescein thiocyanate-vinyl aniline. As a result this 100 % sulfonated polymer contains no hydrophobic patches along the chain backbone besides the fluorescent marker itself. The concentration of the fluorescent monomer was kept low to maintain the characteristic properties of the anionic polyelectrolyte, LNaPSS. ATRP conditions facilitated the production of polymers spanning a range of molecular weights from 35,000 to 175,000 in gram-scale batches with polydispersity indices of 1.01-1.24. Molecular weight increased with the monomer to initiator ratio. Gel permeation chromatography results show a unimodal distribution, and the polymer structure was also confirmed by (1)H NMR and FT-IR spectroscopy. Fluorescence spectroscopy confirmed covalent bonding of fluorescein isothiocyanate to the polymer, indicating that the polymer is suitable as a probe in fluorescence microscopy. To demonstrate this ability, the polymer was used to locate structural features in salt crystals formed during drying, as in the evaporation of sea mist. A second application to probe diffusion studies is also demonstrated. PMID:26745991

  16. Metastable Magnesium fluorescence spectroscopy using a frequency-stabilized 517 nm laser

    DEFF Research Database (Denmark)

    He, Ming; Jensen, Brian B; Therkildsen, Kasper T;

    2009-01-01

    We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we...... obtained more than 40 mW of 517 nm output power by single pass frequency doubling. In addition, fluorescence spectroscopy of metastable magnesium atoms could be used to stabilize the 517 nm laser to an absolute frequency within 1 MHz....

  17. "FluSpec": A Simulated Experiment in Fluorescence Spectroscopy

    Science.gov (United States)

    Bigger, Stephen W.; Bigger, Andrew S.; Ghiggino, Kenneth P.

    2014-01-01

    The "FluSpec" educational software package is a fully contained tutorial on the technique of fluorescence spectroscopy as well as a simulator on which experiments can be performed. The procedure for each of the experiments is also contained within the package along with example analyses of results that are obtained using the software.

  18. Fluorescence Correlation Spectroscopy Applied to Living Plant Cells

    NARCIS (Netherlands)

    Hink, M.A.

    2002-01-01

    Keywords: Fluorescence correlation spectroscopy, photon counting histogram, intracellular, plant, AtSERK1In order to survive organisms have to be capable to adjust theirselves to changes in the environment. Cells, the building blocks of an organism react to these

  19. Fluorescence spectroscopy: a rapid tool for analyzing dairy products.

    Science.gov (United States)

    Andersen, Charlotte Møller; Mortensen, Grith

    2008-02-13

    This paper gives a critical evaluation of the use of fluorescence spectroscopy for measuring chemical and physical changes in dairy products caused by processing and storage. Fluorescence spectroscopy is able to determine various properties of foods without use of chemicals and time-consuming sample preparation. This is shown by examples where the measurement of a given chemical parameter has been appropriately described and validated, as well as situations showing potential applications, but where further research and validation is required. The interpretation of fluorescence spectroscopic data is complex due to absorbance by other molecular groups, changes caused by variation in the sample matrix, etc. It is illustrated how advanced data analytical techniques are required to obtain optimal interpretation of the data. Even though the review focuses on examples from the dairy industry, the principles are broader and can be applied to other fields of food and agricultural research.

  20. Single-atom-sensitive fluorescence imaging of ultracold quantum gases

    CERN Document Server

    Bücker, R; Manz, S; Betz, T; Koller, Ch; Plisson, T; Rottmann, J; Schumm, T; Schmiedmayer, J

    2009-01-01

    We present a novel imaging system for ultracold quantum gases in expansion. After release from a confining potential, atoms fall through a sheet of resonant excitation laser light and the emitted fluorescence photons are imaged onto an amplified CCD camera using a high numerical aperture optical system. The imaging system reaches an extraordinary dynamic range, not attainable with conventional absorption imaging. We demonstrate single-atom detection for dilute atomic clouds with high efficiency where at the same time dense Bose-Einstein condensates can be imaged without saturation or distortion. The spatial resolution can reach the sampling limit as given by the 8 microns pixel size in object space. Pulsed operation of the detector allows for slice images and hence a 3D tomography of the measured object. The scheme can easily be implemented for any atomic species and all optical components are situated outside the vacuum system. As a first application we perform thermometry on rubidium Bose-Einstein condensat...

  1. Energy dissipation in matrix-isolated silver atoms: A time-resolved fluorescence study

    Science.gov (United States)

    Wiggenhauser, H.; Schroeder, W.; Kolb, D. M.

    1988-03-01

    The fluorescence from optically excited Ag atoms in Ar, Kr, and Xe matrices has been investigated in a time-resolved synchrotron-radiation study. A detailed energy dissipation model could be established from a systematic analysis of rise and decay times of all the observed fluorescence bands after pulsed excitation into the Ag (4d105p)2P1/2,3/2 levels, and by setting time windows between the excitation pulses in emission and emission-yield spectroscopy. Although the overall wavelength dependence of the decay time follows the λ3 law, the decay time is independent of λ within a given emission band. Finally, the role of energy transfer between Ag atoms and dimers for the evaluation of decay times is briefly addressed.

  2. Optical Frequency Comb Spectroscopy of Rare Earth Atoms

    Science.gov (United States)

    Swiatlowski, Jerlyn; Palm, Christopher; Joshi, Trinity; Montcrieffe, Caitlin; Jackson Kimball, Derek

    2013-05-01

    We discuss progress in our experimental program to employ optical-frequency-comb-based spectroscopy to understand the complex spectra of rare-earth atoms. We plan to carry out systematic measurements of atomic transitions in rare-earth atoms to elucidate the energy level structure and term assignment and determine presently unknown atomic state parameters. This spectroscopic information is important in view of the increasing interest in rare-earth atoms for atomic frequency standards, in astrophysical investigations of chemically peculiar stars, and in tests of fundamental physics (tests of parity and time-reversal invariance, searches for time variation of fundamental constants, etc.). We are presently studying the use of hollow cathode lamps as atomic sources for two-photon frequency comb spectroscopy. Supported by the National Science Foundation under grant PHY-0958749.

  3. Photonic Methods to Enhance Fluorescence Correlation Spectroscopy and Single Molecule Fluorescence Detection

    OpenAIRE

    Hervé Rigneault; Jérome Wenger

    2010-01-01

    Recent advances in nanophotonics open the way for promising applications towards efficient single molecule fluorescence analysis. In this review, we discuss how photonic methods bring innovative solutions for two essential questions: how to detect a single molecule in a highly concentrated solution, and how to enhance the faint optical signal emitted per molecule? The focus is set primarily on the widely used technique of fluorescence correlation spectroscopy (FCS), yet the discussion can be ...

  4. Design of a WWW database server for Atomic Spectroscopy Data

    Energy Technology Data Exchange (ETDEWEB)

    Contis, A.

    1995-12-01

    The department of Atomic Spectroscopy at Lund Univ produces large amounts of experimental data on energy levels and emissions for atomic systems. In order to make this data easily available to users outside the institution, a database has been produced and made available on the Internet. This report describes the organization of the data and the Internet interface of the data base. 4 refs.

  5. THE SPECTROSCOPY OF URANIUM ATOM WITHIN THE "SILVA" PROGRAM

    OpenAIRE

    Avril, R.; Ebrardt, J.; Petit, A.; Viala, F.; Vors, E.

    1987-01-01

    Atomic vapor laser isotope separation (SILVA) has been recognized as beeing an attractive powerful technique for the enrichment of uranium for light water reactor fuel. Since the heart of the AVLIS process is based on selective multistep photoionization of an uranium atomic vapor stream, the development of this process in France, has stimulated intensive studies in the field of uranium spectroscopy.

  6. Resonance fluorescence of a trapped three-level atom

    CERN Document Server

    Bienert, M; Morigi, G; Bienert, Marc; Merkel, Wolfgang; Morigi, Giovanna

    2003-01-01

    We investigate theoretically the spectrum of resonance fluorescence of a harmonically trapped atom, whose internal transitions are $\\Lambda$--shaped and driven at two-photon resonance by a pair of lasers, which cool the center--of--mass motion. For this configuration, photons are scattered only due to the mechanical effects of the quantum interaction between light and atom. We study the spectrum of emission in the final stage of laser--cooling, when the atomic center-of-mass dynamics is quantum mechanical and the size of the wave packet is much smaller than the laser wavelength (Lamb--Dicke limit). We use the spectral decomposition of the Liouville operator of the master equation for the atomic density matrix and apply second order perturbation theory. We find that the spectrum of resonance fluorescence is composed by two narrow sidebands -- the Stokes and anti-Stokes components of the scattered light -- while all other signals are in general orders of magnitude smaller. For very low temperatures, however, th...

  7. Resonance ionization spectroscopy: Counting noble gas atoms

    International Nuclear Information System (INIS)

    The purpose of this paper is to describe new work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions). When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. We show that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective. (orig./FKS)

  8. Fluorescence suppression using micro-scale spatially offset Raman spectroscopy.

    Science.gov (United States)

    Conti, Claudia; Botteon, Alessandra; Colombo, Chiara; Realini, Marco; Matousek, Pavel

    2016-09-21

    We present a new concept of fluorescence suppression in Raman microscopy based on micro-spatially offset Raman spectroscopy which is applicable to thin stratified turbid (diffusely scattering) matrices permitting the retrieval of the Raman signals of sublayers below intensely fluorescing turbid over-layers. The method is demonstrated to yield good quality Raman spectra with dramatically suppressed fluorescence backgrounds enabling the retrieval of Raman sublayer signals even in situations where conventional Raman microscopy spectra are fully overwhelmed by intense fluorescence. The concept performance was studied theoretically using Monte Carlo simulations indicating the potential of up to an order or two of magnitude suppression of overlayer fluorescence backgrounds relative to the Raman sublayer signals. The technique applicability was conceptually demonstrated on layered samples involving paints, polymers and stones yielding fluorescence suppression factors between 12 to above 430. The technique has potential applications in a number of analytical areas including cultural heritage, archaeology, polymers, food, pharmaceutical, biological, biomedical, forensics and catalytic sciences and quality control in manufacture.

  9. Intramolecular fluorescence correlation spectroscopy in a feedback tracking microscope

    CERN Document Server

    McHale, Kevin

    2009-01-01

    We derive the statistics of the signals generated by shape fluctuations of large molecules studied by feedback tracking microscopy. We account for the influence of intramolecular dynamics on the response of the tracking system, and derive a general expression for the fluorescence autocorrelation function that applies when those dynamics are linear. We show that tracking provides enhanced sensitivity to translational diffusion, molecular size, heterogeneity and long time-scale decays in comparison to traditional fluorescence correlation spectroscopy. We demonstrate our approach by using a three-dimensional tracking microscope to study genomic $\\lambda$-phage DNA molecules with various fluorescence label configurations. We conclude with a discussion of related techniques, including computation of the relevant statistics for camera-based intramolecular correlation measurements.

  10. Fluorescence spectroscopy using indocyanine green for lymph node mapping

    Science.gov (United States)

    Haj-Hosseini, Neda; Behm, Pascal; Shabo, Ivan; Wârdell, Karin

    2014-02-01

    The principles of cancer treatment has for years been radical resection of the primary tumor. In the oncologic surgeries where the affected cancer site is close to the lymphatic system, it is as important to detect the draining lymph nodes for metastasis (lymph node mapping). As a replacement for conventional radioactive labeling, indocyanine green (ICG) has shown successful results in lymph node mapping; however, most of the ICG fluorescence detection techniques developed are based on camera imaging. In this work, fluorescence spectroscopy using a fiber-optical probe was evaluated on a tissue-like ICG phantom with ICG concentrations of 6-64 μM and on breast tissue from five patients. Fiber-optical based spectroscopy was able to detect ICG fluorescence at low intensities; therefore, it is expected to increase the detection threshold of the conventional imaging systems when used intraoperatively. The probe allows spectral characterization of the fluorescence and navigation in the tissue as opposed to camera imaging which is limited to the view on the surface of the tissue.

  11. 微波消解氢化物原子荧光法测定食品中的砷和汞%Simultaneous determination of arsenic and mercury in food by microwave digestion and atomic fluorescence spectroscopy

    Institute of Scientific and Technical Information of China (English)

    郭同兵; 黄谦; 刘剑波

    2011-01-01

    A process of closed and high pressure microwave digestion with atomic fluorescence spectrometer for simultaneously determine As and Hg in food was established. Compared with traditional wet digestion method, the microwave digestion features simple operation, fast, little interference and excellent process controllability. After detect rice, meat, mineral water.aquatic product and so on, we find the detection limits for arsenic and mercury were 0. 030 6 μg/L and 0. 005 2 μg/L respectively. The relative standard deviation for As was 2. 40%,while 1. 39% for Hg. The recovery for As was in the rang of 99. 4% - 101. 2% and 94. 5%~ 106. 5% for Hg. And the As correlation coefficient was 0. 999 7, while the Hg was 0. 999 6. The result is fine, and is fit for simultaneously determine As and Hg in food.%采用高压密闭微波消解氢化物原子荧光法对食品中砷、汞进行同时测定,并与传统的湿法消解进行比较.结果表明:该法具有操作简单、快速、干扰少、良好的过程可控性等优点.通过对大米、肉类罐头、矿采水和水产品等样品的检测,发现砷、汞的检出限分别为0.0306,0.0052 μg/L;相对标准偏差(RSD):砷为2.40%,Hg为1.39%;回收率:As为99.4%~101.2%,Hg为94.5%~106.5%;相关系数(r):As为0.999 7,Hg为0.999 6.结果良好,适用于多种食品中砷和采的同时检测.

  12. Extreme ultraviolet fluorescence spectroscopy of pure and core-shell rare gas clusters at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Schroedter, Lasse

    2013-08-15

    The interaction of rare gas clusters with short-wavelength radiation of free-electron lasers (FELs) has been studied extensively over the last decade by means of electron and ion time-of-flight spectroscopy. This thesis describes the design and construction of a fluorescence spectrometer for the extreme ultraviolet (XUV) spectral range and discusses the cluster experiments performed at FLASH, the Free-electron LAser in Hamburg. Fluorescence of xenon and of argon clusters was studied, both in dependence on the FEL pulse intensity and on the cluster size. The FEL wavelength was set to the giant 4d-resonance of xenon at 13.5 nm and the FEL pulse intensity reached peak values of 2.7.10{sup 15} W/cm{sup 2}. For xenon clusters, charge states of at least 11+ were identified. For argon, charge states up to 7+ were detected. The cluster-size dependent study revealed a decrease of the fluorescence yield per atom with increasing cluster size. This decrease is explained with the help of a geometric model. It assumes that virtually the entire fluorescence yield stems from shells of ions on the cluster surface, whereas ions in the cluster core predominantly recombine non-radiatively with electrons. However, the detailed analysis of fluorescence spectra from clusters consisting of a core of Xe atoms and a surrounding shell of argon atoms shows that, in fact, a small fraction of the fluorescence signal comes from Xe ions in the cluster core. Interestingly, these ions are as highly charged as the ions in the shells of a pure Xe cluster. This result goes beyond the current understanding of charge and energy transfer processes in these systems and points toward the observation of ultrafast charging dynamics in a time window where mass spectrometry is inherently blind. (orig.)

  13. Stark Spectroscopy of Rubrene. II. Stark Fluorescence Spectroscopy and Fluorescence Quenching Induced by an External Electric Field.

    Science.gov (United States)

    Iimori, Toshifumi; Ito, Ryuichi; Ohta, Nobuhiro

    2016-07-21

    We report Stark fluorescence spectroscopy investigation of rubrene dispersed in a poly(methyl methacrylate) film. The features of the fluorescence spectrum are analogous to those in solutions. In the Stark fluorescence spectrum, the decrease of the fluorescence quantum yield in the presence of an external electric field is observed. This result shows that the yield of nonradiative decay processes is increased by the application of an external electric field. It is known that the fluorescence quantum yield for rubrene, which is nearly unity at room temperature, depends on temperature, and a major nonradiative decay process in photoexcited rubrene is ascribed to a thermally activated intersystem crossing (ISC). Equations that express the field-induced fluorescence quenching in terms of the molecular parameters are derived from the ensemble average of electric field effects on the activation energy of the reaction rate constant in random orientation systems. The molecular parameters are then extracted from the observed data. It is inferred that the field-induced increase in the yield of other intramolecular and intermolecular photophysical processes in addition to the ISC should be taken into account. PMID:27341859

  14. Ablation plume structure and dynamics in ambient gas observed by laser-induced fluorescence imaging spectroscopy

    Science.gov (United States)

    Miyabe, M.; Oba, M.; Iimura, H.; Akaoka, K.; Khumaeni, A.; Kato, M.; Wakaida, I.

    2015-08-01

    The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5-6 J/cm2) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis.

  15. Fluorescence Quenching of Benzaldehyde in Water by Hydrogen Atom Abstraction.

    Science.gov (United States)

    Fletcher, Katharyn; Bunz, Uwe H F; Dreuw, Andreas

    2016-09-01

    We computed the mechanism of fluorescence quenching of benzaldehyde in water through relaxed potential energy surface scans. Time-dependent density functional theory calculations along the protonation coordinate from water to benzaldehyde reveal that photoexcitation to the bright ππ* (S3 ) state is immediately followed by ultrafast decay to the nπ* (S1 ) state. Evolving along this state, benzaldehyde (BA) abstracts a hydrogen atom, resulting in a BAH(.) and OH(.) radical pair. Benzaldehyde does not act as photobase in water, but abstracts a hydrogen atom from a nearby solvent molecule. The system finally decays back to the ground state by non-radiative decay and an electron transfers back to the OH(.) radical. Proton transfer from BAH(+) to OH(-) restores the initial situation, BA in water.

  16. Fluorescence detection at the atom shot noise limit for atom interferometry

    CERN Document Server

    Rocco, Emanuele; Valenzuela, Tristan; Boyer, Vincent; Freise, Andreas; Bongs, Kai

    2014-01-01

    Atom interferometers are promising tools for precision measurement with applications ranging from geophysical exploration to tests of the equivalence principle of general relativity, or the detection of gravitational waves. Their optimal sensitivity is ultimately limited by their detection noise. We review resonant and near-resonant methods to detect the atom number of the interferometer outputs and we theoretically analyze the relative influence of various scheme dependent noise sources and the technical challenges affecting the detection. We show that for the typical conditions under which an atom interferometer operates, simultaneous fluorescence detection with a CCD sensor is the optimal imaging scheme. We extract the laser beam parameters such as detuning, intensity, and duration, required for reaching the atom shot noise limit.

  17. Solving a Mock Arsenic-Poisoning Case Using Atomic Spectroscopy

    Science.gov (United States)

    Tarr, Matthew A.

    2001-01-01

    A new upper-level undergraduate atomic spectroscopy laboratory procedure has been developed that presents a realistic problem to students and asks them to assist in solving it. Students are given arsenic-laced soda samples from a mock crime scene. From these samples, they are to gather evidence to help prosecute a murder suspect. The samples are analyzed by inductively coupled plasma atomic emission spectroscopy or by atomic absorbance spectroscopy to determine the content of specific metal impurities. By statistical comparison of the samples' composition, the students determine if the soda samples can be linked to arsenic found in the suspect's home. As much as possible, the procedures and interpretations are developed by the students. Particular emphasis is placed on evaluating the limitations and capabilities of the analytical method with respect to the demands of the problem.

  18. Detection of single atoms by resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the technique of resonance ionization spectroscopy (RIS), a laser is tuned to a wavelength that will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or non-resonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms: and because detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples of one-atom detection are given, including that of the noble gases, to show complementarity with accelerator mass spectrometry AMS methods. For instance, the detection of 81Kr by using RIS has interesting applications for solar-neutrino research, ice-cap dating, and groundwater dating. (author)

  19. Modulation transfer spectroscopy of ytterbium atoms in hollow cathode lamp

    International Nuclear Information System (INIS)

    We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp. The dependences of its linewidth, slope and magnitude on the various experimental parameters are measured and fitted by the well-known theoretical expressions. The experimental results are in good agreement with the theoretical prediction. We have observed the Dicke narrowing effect by increasing the current of the hollow cathode lamp. It is also found that there are the optimal current and laser power to generate the better modulation transfer spectroscopy signal, which can be employed for locking the laser frequency to the atomic transition. (authors)

  20. Deuteron charge radius from spectroscopy data in atomic deuterium

    CERN Document Server

    Pohl, Randolf; Udem, Thomas; Antognini, Aldo; Beyer, Axel; Fleurbaey, Hélène; Grinin, Alexey; Hänsch, Theodor W; Julien, Lucile; Kottmann, Franz; Krauth, Julian J; Maisenbacher, Lothar; Matveev, Arthur; Biraben, François

    2016-01-01

    We give a pedagogical description of the method to extract the charge radii and Rydberg constant from laser spectroscopy in regular hydrogen (H) and deuterium (D) atoms, that is part of the CODATA least-squares adjustment of the fundamental physical constants. We give a deuteron charge radius from D spectroscopy alone of 2.1415(45) fm. This value is independent of the proton charge radius, and five times more accurate than the value found in the CODATA Adjustment 10.

  1. Electron spectroscopy of collisional excited atoms

    International Nuclear Information System (INIS)

    In this thesis measurements are described in which coincidences are detected between scattered projectiles and emitted electrons. This yields information on two-electron excitation processes. In order to show what can be learnt from coincidence experiments a detailed theoretical analysis is given. The transition amplitudes, which contain all the information, are introduced (ch.2). In ch.3 the experimental set-up is shown. The results for the Li+-He system are shown in ch. 7 and are compared with predictions based on the Molecular-Orbitalmodel which however does not account for two-excitation mechanisms. With the transition amplitudes also the wave function of the excited atom has been completely determined. In ch.8 the shape of the electron cloud, induced by the collision, is derived from the amplitudes. The relation between the oscillatory motion of this cloud after the collision and the correlation between the two electrons of the excited atom is discussed. In ch. 6 it is shown that the broad structures in the non-coincident energy spectra of the Li+-He system are erroneously interpretated as a result of electron emission from the (Li-He)+-quasimolecule. A model is presented which explains, based on the results obtained from the coincidence measurements, these broad structures. In ch. 4 the Post-Collision Interaction process is treated. It is shown that for high-energy collisions, in contrast with general assumptions, PCI is important. In ch. 5 the importance of PCI-processes in photoionization of atoms, followed by Auger decay, are studied. From the formulas derived in ch. 4 simple analytical results are obtained. These are applied to recent experiments and good agreement is achieved. 140 refs.; 55 figs.; 9 tabs

  2. An Analog Filter Approach to Frequency Domain Fluorescence Spectroscopy.

    Science.gov (United States)

    Trainham, R; O'Neill, M; McKenna, I J

    2015-11-01

    The rate equations found in frequency domain fluorescence spectroscopy are the same as those found in electronics under analog filter theory. Laplace transform methods are a natural way to solve the equations, and the methods can provide solutions for arbitrary excitation functions. The fluorescence terms can be modelled as circuit components and cascaded with drive and detection electronics to produce a global transfer function. Electronics design tools such as SPICE can be used to model fluorescence problems. In applications, such as remote sensing, where detection electronics are operated at high gain and limited bandwidth, a global modelling of the entire system is important, since the filter terms of the drive and detection electronics affect the measured response of the fluorescence signals. The techniques described here can be used to separate signals from fast and slow fluorophores emitting into the same spectral band, and data collection can be greatly accelerated by means of a frequency comb driver waveform and appropriate signal processing of the response. The simplification of the analysis mathematics, and the ability to model the entire detection chain, make it possible to develop more compact instruments for remote sensing applications. PMID:26429345

  3. Cytoskeleton dynamics studied by dispersion-relation fluorescence spectroscopy

    Science.gov (United States)

    Wang, Ru; Lei, Lei; Wang, Yingxiao; Levine, Alex; Popescu, Gabriel

    2013-03-01

    Fluorescence is the most widely used microscopy technique for studying the dynamics and function in both medical and biological sciences due to its sensitivity and specificity. Inspired by the spirit of spatial fluorescence correlation spectroscopy, we propose a new method to study the transport dynamics over a broad range of spatial and temporal scales. The molecules of interest are labeled with a fluorophore whose motion gives rise to spontaneous fluorescence intensity fluctuations that can be further analyzed to quantify the governing molecular mass transport dynamics. We analyze these data by the dispersion relation in the form of a power law, Γ(q) ~qα , which describe the relaxation rate of fluorescence intensity fluctuations, Γ, vs. the wavenumber, q. We used this approach to study the interplay of various cytoskeletal components in intracellular transport under the influence of protein-motor inhibitors. We found that after actin is depolymerized, the transport becomes completely random for a few minutes and then it starts to organize deterministically again. We conclude that the disrupted cytoskeletal components first diffuse in the cytoplasm, but then become attached to microtubules and get transported deterministically.

  4. Brain cancer probed by native fluorescence and stokes shift spectroscopy

    Science.gov (United States)

    Zhou, Yan; Liu, Cheng-hui; He, Yong; Pu, Yang; Li, Qingbo; Wang, Wei; Alfano, Robert R.

    2012-12-01

    Optical biopsy spectroscopy was applied to diagnosis human brain cancer in vitro. The spectra of native fluorescence, Stokes shift and excitation spectra were obtained from malignant meningioma, benign, normal meningeal tissues and acoustic neuroma benign tissues. The wide excitation wavelength ranges were used to establish the criterion for distinguishing brain diseases. The alteration of fluorescence spectra between normal and abnormal brain tissues were identified by the characteristic fluorophores under the excitation with UV to visible wavelength range. It was found that the ratios of the peak intensities and peak position in both spectra of fluorescence and Stokes shift may be used to diagnose human brain meninges diseases. The preliminary analysis of fluorescence spectral data from cancer and normal meningeal tissues by basic biochemical component analysis model (BBCA) and Bayes classification model based on statistical methods revealed the changes of components, and classified the difference between cancer and normal human brain meningeal tissues in a predictions accuracy rate is 0.93 in comparison with histopathology and immunohistochemistry reports (gold standard).

  5. Laser-excited fluorescence spectroscopy of oxide glasses

    International Nuclear Information System (INIS)

    Laser-induced fluorescence line narrowing was applied to investigate the local fields and interactions of paramagnetic ions in oxide glasses. Studies included the site dependence of energy levels, radiative and nonradiative transition probabilities, homogeneous line broadening, and ion--ion energy transfer of rare earth ions. These results and the experimental techniques are reviewed briefly; the use of paramagnetic ions other than the rare earths is also considered. Recently, laser-excited fluorescence spectroscopy was used to investigate modifications in the local structure of lithium borate glass caused by compositional changes and phase separation and the site dependence of nonradiative relaxation of paramagnetic ions by multiphonon processes. These results and their implications are discussed. 6 figures

  6. Method for laser spectroscopy of metastable pionic helium atoms

    International Nuclear Information System (INIS)

    The PiHe collaboration is currently attempting to carry out laser spectroscopy of metastable pionic helium atoms using the high-intensity π− beam of the ring cyclotron facility of the Paul Scherrer Institute. These atoms are heretofore hypothetical three-body Coulomb systems each composed of a helium nucleus, a π− occupying a Rydberg state, and an electron occupying the 1s ground state. We briefly review the proposed method by which we intend to detect the laser spectroscopic signal. This complements our experiments on metastable antiprotonic helium atoms at CERN

  7. Method for laser spectroscopy of metastable pionic helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Hori, M., E-mail: Masaki.Hori@mpq.mpg.de; Sótér, A.; Aghai-Khozani, H. [Max-Planck-Institut für Quantenoptik (Germany); Barna, D. [CERN (Switzerland); Dax, A. [Paul Scherrer Institut (Switzerland); Hayano, R. S.; Murakami, Y.; Yamada, H. [University of Tokyo, Department of Physics (Japan)

    2015-08-15

    The PiHe collaboration is currently attempting to carry out laser spectroscopy of metastable pionic helium atoms using the high-intensity π{sup −} beam of the ring cyclotron facility of the Paul Scherrer Institute. These atoms are heretofore hypothetical three-body Coulomb systems each composed of a helium nucleus, a π{sup −} occupying a Rydberg state, and an electron occupying the 1s ground state. We briefly review the proposed method by which we intend to detect the laser spectroscopic signal. This complements our experiments on metastable antiprotonic helium atoms at CERN.

  8. Quantum process tomography by 2D fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pachón, Leonardo A. [Grupo de Física Atómica y Molecular, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 (United States); Marcus, Andrew H. [Department of Chemistry and Biochemistry, Oregon Center for Optics, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403 (United States); Aspuru-Guzik, Alán [Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2015-06-07

    Reconstruction of the dynamics (quantum process tomography) of the single-exciton manifold in energy transfer systems is proposed here on the basis of two-dimensional fluorescence spectroscopy (2D-FS) with phase-modulation. The quantum-process-tomography protocol introduced here benefits from, e.g., the sensitivity enhancement ascribed to 2D-FS. Although the isotropically averaged spectroscopic signals depend on the quantum yield parameter Γ of the doubly excited-exciton manifold, it is shown that the reconstruction of the dynamics is insensitive to this parameter. Applications to foundational and applied problems, as well as further extensions, are discussed.

  9. Advantage of Fluorescence Correlation Spectroscopy for the Study of Polyelectrolytes

    Institute of Scientific and Technical Information of China (English)

    贾鹏翔; 宫永宽; 王生勤; 赵江

    2012-01-01

    The advantage of fluorescence correlation spectroscopy to study single chain behavior of polyelectrolytes has been demonstrated by checking the coil-to-globule transition ofpoly 2-vinylpyridine with the change ofpH value in aqueous solution. The ultra-high sensitivity of FCS allows measurement at extreme dilution where the effect of electrostatic interaction between the chains is greatly suppressed. The results exposed first-order conformation tran- sition of P2VP as detected by FCS while inter-chain aggregation occurred in the experiments of dynamic light scat- tering.

  10. Determination of antioxidant content in biodiesel by fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes, Keurison F.; Caires, Anderson R.L. [Universidade Federal da Grande Dourados, MS (Brazil). Grupo de Optica Aplicada; Oliveira, Samuel L. [Universidade Federal de Mato Grosso do Sul (UFMS), MS (Brazil). Grupo de Optica e Fotonica

    2011-07-01

    Full text. Biodiesel is an alternative fuel composed by mono-alkyl esters obtained from vegetable oils or animal fats. Due to its chemical structure, biodiesel is highly susceptible to oxidation which leads to formation of insoluble gums and sediments that can block the filter system of fuel injection. Biodiesel made from vegetable oils typically has a small amount of natural antioxidants so that it is necessary to add synthetic antioxidants to enhance its stability and retain their properties for a longer period. The main antioxidants are synthetic phenolic compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) as well as natural antioxidants as tocopherols. The fluorescence spectroscopy has been applied for determination of phenolic compounds in oils. Here, a method based on fluorescence is proposed to quantify the BHA and TBHQ antioxidant concentration in biodiesel produced from sunflower and soybean oils. Soybean and sunflower biodiesel were obtained by transesterification of fatty alcohol in the presence of NaOH as catalyst. The reactions were carried out in the molar ratio of 6:1 methanol/oil. After the production and purification, biodiesel samples were stored. Biodiesel samples with BHA and TBHQ concentrations from 1000 to 8000 ppm (m/m) were pre- pared. These samples were diluted in ethanol (95%) in order to measure the fluorescence spectra. Fluorescence and excitation spectra of the solutions were recorded at room temperature using a spectrofluorimeter. The emission spectra were obtained under excitation at about 310nm and fluorescence in the 320-800nm range was evaluated. Biodiesel samples without BHA and TBHQ showed fluorescence band at about 420nm, which can be attributed to tocopherols inherent to the vegetable oils used in the biodiesel production. The addition of BHA and/or TBHQ is responsible for the appearance of a fluorescence band around 330nm. It was verified that the fluorescence

  11. Identification of active fluorescence stained bacteria by Raman spectroscopy

    Science.gov (United States)

    Krause, Mario; Beyer, Beatrice; Pietsch, Christian; Radt, Benno; Harz, Michaela; Rösch, Petra; Popp, Jürgen

    2008-04-01

    Microorganisms can be found everywhere e.g. in food both as useful ingredients or harmful contaminations causing food spoilage. Therefore, a fast and easy to handle analysis method is needed to detect bacteria in different kinds of samples like meat, juice or air to decide if the sample is contaminated by harmful microorganisms. Conventional identification methods in microbiology require always cultivation and therefore are time consuming. In this contribution we present an analysis approach to identify fluorescence stained bacteria on strain level by means of Raman spectroscopy. The stained bacteria are highlighted and can be localized easier against a complex sample environment e.g. in food. The use of Raman spectroscopy in combination with chemometrical methods allows the identification of single bacteria within minutes.

  12. Fluorescence-excitation and Emission Spectroscopy on Single FMO Complexes.

    Science.gov (United States)

    Löhner, Alexander; Ashraf, Khuram; Cogdell, Richard J; Köhler, Jürgen

    2016-08-22

    In green-sulfur bacteria sunlight is absorbed by antenna structures termed chlorosomes, and transferred to the RC via the Fenna-Matthews-Olson (FMO) complex. FMO consists of three monomers arranged in C3 symmetry where each monomer accommodates eight Bacteriochlorophyll a (BChl a) molecules. It was the first pigment-protein complex for which the structure has been determined with high resolution and since then this complex has been the subject of numerous studies both experimentally and theoretically. Here we report about fluorescence-excitation spectroscopy as well as emission spectroscopy from individual FMO complexes at low temperatures. The individual FMO complexes are subjected to very fast spectral fluctuations smearing out any possible different information from the ensemble data that were recorded under the same experimental conditions. In other words, on the time scales that are experimentally accessible by single-molecule techniques, the FMO complex exhibits ergodic behaviour.

  13. Synthesis of Ag clusters in microemulsions: A time-resolved UV vis and fluorescence spectroscopy study

    Science.gov (United States)

    Ledo, Ana; Martínez, F.; López-Quintela, M. A.; Rivas, J.

    2007-09-01

    The combined use of the microemulsion technique and the kinetic control allows the preparation of small silver clusters. By using UV-vis and fluorescence spectroscopy the main stages by which the clusters grow, before the formation of nanoparticles, were elucidated. Transmission electron microscopy (TEM) and scanning tunnelling microscopy (STM) were used to further characterize the samples. Two main stages were clearly identified, which are associated with: (1) the formation of Ag n clusters with n<10, which self-aggregate into one atom high 2D nanodiscs of 3.2 nm size and (2) Ag n clusters, which self-aggregate into 3D nanostructures of 1.5 nm in size. The fluorescence properties observed with both stages show that the formed clusters are small enough to display a molecule-like behaviour.

  14. Application of dynamic impedance spectroscopy to atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Kazimierz Darowicki, Artur Zieliński and Krzysztof J Kurzydłowski

    2008-01-01

    Full Text Available Atomic force microscopy (AFM is a universal imaging technique, while impedance spectroscopy is a fundamental method of determining the electrical properties of materials. It is useful to combine those techniques to obtain the spatial distribution of an impedance vector. This paper proposes a new combining approach utilizing multifrequency scanning and simultaneous AFM scanning of an investigated surface.

  15. Developing a Transdisciplinary Teaching Implement for Atomic Absorption Spectroscopy

    Science.gov (United States)

    Drew, John

    2008-01-01

    In this article I explain why I wrote the set of teaching notes on Atomic Absorption Spectroscopy (AAS) and why they look the way they do. The notes were intended as a student reference to question, highlight and write over as much as they wish during an initial practical demonstration of the threshold concept being introduced, in this case…

  16. SPECTRW: A software package for nuclear and atomic spectroscopy

    Science.gov (United States)

    Kalfas, C. A.; Axiotis, M.; Tsabaris, C.

    2016-09-01

    A software package to be used in nuclear and atomic spectroscopy is presented. Apart from analyzing γ and X-ray spectra, it offers many additional features such as de-convolution of multiple photopeaks, sample analysis and activity determination, detection system evaluation and an embedded code for spectra simulation.

  17. Current Status of Atomic Spectroscopy Databases at NIST

    Science.gov (United States)

    Kramida, Alexander; Ralchenko, Yuri; Reader, Joseph

    2016-05-01

    NIST's Atomic Spectroscopy Data Center maintains several online databases on atomic spectroscopy. These databases can be accessed via the http://physics.nist.gov/PhysRefData web page. Our main database, Atomic Spectra Database (ASD), recently upgraded to v. 5.3, now contains critically evaluated data for about 250,000 spectral lines and 109,000 energy levels of almost all elements in the periodic table. This new version has added several thousand spectral lines and energy levels of Sn II, Mo V, W VIII, and Th I-III. Most of these additions contain critically evaluated transition probabilities important for astrophysics, technology, and fusion research. A new feature of ASD is providing line-ratio data for diagnostics of electron temperature and density in plasmas. Saha-Boltzmann plots have been modified by adding an experimental feature allowing the user to specify a multi-element mixture. We continue regularly updating our bibliography databases, ensuring comprehensive coverage of current literature on atomic spectra for energy levels, spectral lines, transition rates, hyperfine structure, isotope shifts, Zeeman and Stark effects. Our other popular databases, such as the Handbook of Basic Atomic Spectroscopy Data, searchable atlases of spectra of Pt-Ne and Th-Ne lamps, and non-LTE plasma-kinetics code comparisons, continue to be maintained.

  18. Atomic spectroscopy introduction to the theory of hyperfine structure

    CERN Document Server

    Andreev, Anatoli V

    2006-01-01

    Atomic Spectroscopy provides a comprehensive discussion on the general approach to the theory of atomic spectra, based on the use of the Lagrangian canonical formalism. This approach is developed and applied to explain the hydrogenic hyperfine structure associated with the nucleus motion, its finite mass, and spin. The non-relativistic or relativistic, spin or spin-free particle approximations can be used as a starting point of general approach. The special attention is paid to the theory of Lamb shift formation. The formulae for hydrogenic spectrum including the account of Lamb shift are written in simple analytical form. The book is of interest to specialists, graduate and postgraduate students, who are involved into the experimental and theoretical research in the field of modern atomic spectroscopy.

  19. Classification of plum spirit drinks by synchronous fluorescence spectroscopy.

    Science.gov (United States)

    Sádecká, J; Jakubíková, M; Májek, P; Kleinová, A

    2016-04-01

    Synchronous fluorescence spectroscopy was used in combination with principal component analysis (PCA) and linear discriminant analysis (LDA) for the differentiation of plum spirits according to their geographical origin. A total of 14 Czech, 12 Hungarian and 18 Slovak plum spirit samples were used. The samples were divided in two categories: colorless (22 samples) and colored (22 samples). Synchronous fluorescence spectra (SFS) obtained at a wavelength difference of 60 nm provided the best results. Considering the PCA-LDA applied to the SFS of all samples, Czech, Hungarian and Slovak colorless samples were properly classified in both the calibration and prediction sets. 100% of correct classification was also obtained for Czech and Hungarian colored samples. However, one group of Slovak colored samples was classified as belonging to the Hungarian group in the calibration set. Thus, the total correct classifications obtained were 94% and 100% for the calibration and prediction steps, respectively. The results were compared with those obtained using near-infrared (NIR) spectroscopy. Applying PCA-LDA to NIR spectra (5500-6000 cm(-1)), the total correct classifications were 91% and 92% for the calibration and prediction steps, respectively, which were slightly lower than those obtained using SFS.

  20. Quantitative Studies of Antimicrobial Peptide Pore Formation in Large Unilamellar Vesicles by Fluorescence Correlation Spectroscopy (FCS)

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2013-01-01

    leakage of fluorescent probes of different sizes through transmembrane pores formed by each of the three representative antimicrobial peptides: melittin, magainin 2, and mastoparan X. The experimental results demonstrate that leakage assays based on fluorescence correlation spectroscopy offer new and...

  1. Probing lipid mobility of raft-exhibiting model membranes by fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Kahya, N; Scherfeld, D; Bacia, K; Poolman, B; Schwille, P

    2003-01-01

    Confocal fluorescence microscopy and fluorescence correlation spectroscopy (FCS) have been employed to investigate the lipid spatial and dynamic organization in giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/ cholesterol. For a certain

  2. The use of fluorescence correlation spectroscopy to probe mitochondrial mobility and intramatrix protein diffusion

    NARCIS (Netherlands)

    P.H.G.M. Willems; H.G. Swarts; M.A. Hink; W.J.H. Koopman

    2009-01-01

    Within cells, functional changes in mitochondrial metabolic state are associated with alterations in organelle mobility, shape, and configuration of the mitochondrial matrix. Fluorescence correlation spectroscopy (FCS) is a technique that measures intensity fluctuations caused by single fluorescent

  3. Remote excitation fluorescence correlation spectroscopy using silver nanowires

    Science.gov (United States)

    Su, Liang; Yuan, Haifeng; Lu, Gang; Hofkens, Johan; Roeffaers, Maarten; Uji-i, Hiroshi

    2014-11-01

    Fluorescence correlation spectroscopy (FCS), a powerful tool to resolve local properties, dynamical process of molecules, rotational and translational diffusion motions, relies on the fluctuations of florescence observables in the observation volume. In the case of rare transition events or small dynamical fluctuations, FCS requires few molecules or even single molecules in the observation volume at a time to minimize the background signals. Metal nanoparticle which possess unique localized surface plasmon resonance (LSPR) have been used to reduce the observation volume down to sub-diffraction limited scale while maintain at high analyst concentration up to tens of micromolar. Nevertheless, the applications of functionalized nanoparticles in living cell are limited due to the continuous diffusion after cell uptake, which makes it difficult to target the region of interests in the cell. In this work, we demonstrate the use of silver nanowires for remote excitation FCS on fluorescent molecules in solution. By using propagation surface plasmon polaritons (SPPs) which supported by the silver nanowire to excite the fluorescence, both illumination and observation volume can be reduced simultaneously. In such a way, less perturbation is induced to the target region, and this will broaden the application scope of silver nanowire as tip in single cell endoscopy.

  4. Ablation plume structure and dynamics in ambient gas observed by laser-induced fluorescence imaging spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miyabe, M.; Oba, M.; Iimura, H.; Akaoka, K.; Khumaeni, A.; Kato, M.; Wakaida, I.

    2015-08-01

    The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5–6 J/cm{sup 2}) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis. - Highlights: • Ablated ground-state species accumulated in a thin hemispherical boundary layer • Inside the layer, a cavity containing a small density of ablated species was formed. • The hemispherical layers of atoms and ions appeared at a nearly identical location. • The measured intensity peak variation was in good agreement with a model prediction. • We ascribed the dominant process for forming the layer to a three

  5. Spectroscopy of PTCDA attached to rare gas samples: clusters vs. bulk matrices. II. Fluorescence emission spectroscopy

    OpenAIRE

    Dvorak, M.; Müller, M; Knoblauch, T.; Bünermann, O.; Rydlo, A.; Minniberger, S.; Harbich, W.; Stienkemeier, F.

    2012-01-01

    The interaction between PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. On the one hand, laser-excited PTCDA-doped large argon, neon and para-hydrogen clusters in comparison with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground st...

  6. Assessing Raw and Treated Water Quality Using Fluorescence Spectroscopy

    Science.gov (United States)

    Bridgeman, J.; Baker, A.

    2006-12-01

    To date, much fluorescence spectroscopy work has focused on the use of techniques to characterize pollution in river water and to fingerprint pollutants such as, inter alia, treated and raw sewage effluent. In the face of tightening water quality standards associated with disinfection byproducts, there exists the need for a surrogate THM parameter which can be measured accurately and quickly at the water treatment works and which will give a satisfactory indication of the THM concentration leaving the water treatment works. In addition, water treatment works and distribution system managers require tools which are simple and quick, yet robust, to monitor plant and unit process performance. We extend the use of fluorescence techniques from raw water quality monitoring to (1) the monitoring of water treatment works intakes and the assessment of water treatment works performance by (2) assessing the removal of dissolved organic matter (DOM) through the unit process stages of various water treatment works treating different raw waters and (3) examining the prevalence of microbiological activity found at service reservoirs in the downstream distribution system. 16 surface water treatment works were selected in the central region of the UK and samples taken at works' intakes, downstream of each unit process, and in the distribution systems. The intakes selected abstract water from a broad range of upland and lowland water sources with varying natural and anthropogenic pollutant inputs and significantly different flows. The treatment works selected offer a range of different, but relatively standard, unit processes. The results demonstrate that raw waters exhibit more fluorescence than (partially) treated waters. However, noticeable differences between each site are observed. Furthermore, differences in unit process performance between works are also identified and quantified. Across all sites, treatment with Granular Activated Carbon is found to yield a significant

  7. Development of atomic spectroscopy technology -Development of ultrasensitive spectroscopic analysis technology

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Hyung Kee; Song Kyoo Suk; Kim, Duk Hyun; Hong, Suk Kyung; Lee, Yong Joo; Lee, Jong Hoon; Yang, Kee Hoh [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-07-01

    For the resonance ionization spectroscopy experiment, erbium and samarium were chosen as test elements and their optimum photoionization schemes for trace analysis have been investigated by using multiphoton spectroscopic techniques. With the optimum scheme, the detection limit of various atoms were measured. For the test of laser induced fluorescence system, calibration curves obtained from lead and cadmium standard solutions were made and Pb concentrations of various unknown solutions were determined. By using the developed differential absorption lidar system, backscattering signals from aerosol and ozone have been measured. Error source, error calibration and data interpretation techniques have been also studied. 60 figs, 8 pix, 28 tabs, 30 refs. (Author).

  8. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    International Nuclear Information System (INIS)

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH4 in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l−1 and 1.0 ng l−1, respectively. - Highlights: • We optimized and compared two hydride atomizers for atomic fluorescence spectrometry. • Miniature diffusion flame and flame-in-gas-shield atomizer were optimized. • The limit of detection for arsenic was 1.0 ng l−1

  9. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    Energy Technology Data Exchange (ETDEWEB)

    Marschner, Karel, E-mail: karel.marschner@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Albertov 8, 128 43 Prague (Czech Republic); Musil, Stanislav; Dědina, Jiří [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-07-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH{sub 4} in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l{sup −1} and 1.0 ng l{sup −1}, respectively. - Highlights: • We optimized and compared two hydride atomizers for atomic fluorescence spectrometry. • Miniature diffusion flame and flame-in-gas-shield atomizer were optimized. • The limit of detection for arsenic was 1.0 ng l{sup −1}.

  10. Single-atom-resolved fluorescence imaging of an atomic Mott insulator

    DEFF Research Database (Denmark)

    Sherson, Jacob; Weitenberg, Christof; Andres, Manuel;

    2010-01-01

    The reliable detection of single quantum particles has revolutionized the field of quantum optics and quantum information processing. For several years, researchers have aspired to extend such detection possibilities to larger-scale, strongly correlated quantum systems 1 , 2 in order to record...... in situ images of a quantum fluid in which each underlying quantum particle is detected. Here we report fluorescence imaging of strongly interacting bosonic Mott insulators in an optical lattice with single-atom and single-site resolution. From our images, we fully reconstruct the atom distribution...... on the lattice and identify individual excitations with high fidelity. A comparison of the radial density and variance distributions with theory provides a precise in situ temperature and entropy measurement from single images. We observe Mott-insulating plateaus with near-zero entropy and clearly resolve...

  11. Quantitative Fluorescence Studies in Living Cells: Extending Fluorescence Fluctuation Spectroscopy to Peripheral Membrane Proteins

    Science.gov (United States)

    Smith, Elizabeth Myhra

    The interactions of peripheral membrane proteins with both membrane lipids and proteins are vital for many cellular processes including membrane trafficking, cellular signaling, and cell growth/regulation. Building accurate biophysical models of these processes requires quantitative characterization of the behavior of peripheral membrane proteins, yet methods to quantify their interactions inside living cells are very limited. Because peripheral membrane proteins usually exist both in membrane-bound and cytoplasmic forms, the separation of these two populations is a key challenge. This thesis aims at addressing this challenge by extending fluorescence fluctuation spectroscopy (FFS) to simultaneously measure the oligomeric state of peripheral membrane proteins in the cytoplasm and at the plasma membrane. We developed a new method based on z-scan FFS that accounts for the fluorescence contributions from cytoplasmic and membrane layers by incorporating a fluorescence intensity z-scan through the cell. H-Ras-EGFP served as a model system to demonstrate the feasibility of the technique. The resolvability and stability of z-scanning was determined as well as the oligomeric state of H-Ras-EGFP at the plasma membrane and in the cytoplasm. Further, we successfully characterized the binding affinity of a variety of proteins to the plasma membrane by quantitative analysis of the z-scan fluorescence intensity profile. This analysis method, which we refer to as z-scan fluorescence profile deconvoution, was further used in combination with dual-color competition studies to determine the lipid specificity of protein binding. Finally, we applied z-scan FFS to provide insight into the early assembly steps of the HTLV-1 retrovirus.

  12. Detecting Nanodomains in Living Cell Membrane by Fluorescence Correlation Spectroscopy

    Science.gov (United States)

    He, Hai-Tao; Marguet, Didier

    2011-05-01

    Cell membranes actively participate in numerous cellular functions. Inasmuch as bioactivities of cell membranes are known to depend crucially on their lateral organization, much effort has been focused on deciphering this organization on different length scales. Within this context, the concept of lipid rafts has been intensively discussed over recent years. In line with its ability to measure diffusion parameters with great precision, fluorescence correlation spectroscopy (FCS) measurements have been made in association with innovative experimental strategies to monitor modes of molecular lateral diffusion within the plasma membrane of living cells. These investigations have allowed significant progress in the characterization of the cell membrane lateral organization at the suboptical level and have provided compelling evidence for the in vivo existence of raft nanodomains. We review these FCS-based studies and the characteristic structural features of raft nanodomains. We also discuss the findings in regards to the current view of lipid rafts as a general membrane-organizing principle.

  13. Fluorescence Correlation Spectroscopy and Nonlinear Stochastic Reaction-Diffusion

    CERN Document Server

    Del Razo, Mauricio J; Qian, Hong; Lin, Guang

    2014-01-01

    The currently existing theory of fluorescence correlation spectroscopy(FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems here are no closed solutions; therefore, stochastic Monte-Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Our results show that current linear FCS theory could be adequate ...

  14. Fluorescence cross-correlation spectroscopy using single wavelength laser

    Institute of Scientific and Technical Information of China (English)

    Chao XIE; Chaoqing DONG; Jicun REN

    2009-01-01

    In this paper, we first introduced the basic principle of fluorescence cross-correlation spectroscopy (FCCS) and then established an FCCS setup using a single wavelength laser. We systematically optimized the setup, and the detection volume reached about 0.7 fL. The home-built setup was successfully applied for the study of the binding reaction of human immunoglobulin G with goat antihuman immunoglobulin G. Using quantum dots (745 nm emission wavelength) and Rhodamine B (580 nm emission wavelength) as labeling probes and 532 nm laser beam as an excitation source, the cross-talk effect was almost completely suppressed. The molecule numbers in a highly focused volume, the concentration, and the diffusion time and hydrodynamic radii of the reaction products can be determined by FCCS system.

  15. Uranium concentrate analysis by X-ray fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The determination of As, Ca, Fe, Mo, P, S, Si. Th, V and U in uranium concentrates by X-ray fluorescence spectroscopy has been studied. As and U are determined in nitric solutions and for the rest of elements analysis is performed by a bead fusion technique using Li2B4O7 and Li2CO3 as fluxes. Although the uranium matrix minimizes the absorption and enhancement effects, because of the content variations of this element it is advisable to operate at a constant level of U3O8. Despite the high matrix absorption and the large dilution of the samples, sensitivity and speed are found to be satisfactory as the result of the use of a high sensitivity automatic spectrometer. The spectral interferences of Mo on S and P, and of Pb on As have been particularly considered. (author)

  16. Laser spectroscopy of atomic beams of short-lived nuclei

    International Nuclear Information System (INIS)

    A possibility of performing laser-nuclear-spectroscopic experiments at qualitatively new level aimed to solve the second-glass current problem and to search T-non invariant effects in the beta-decay of atomic nuclei is discussed. The question of the increase in efficiency of the experiments, aimed to study the main characteristics of nuclei, far from the beta-stability, by means of the laser spectroscopy methods is considered. 147 refs.; 5 figs.; 1 tab

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-15

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

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

    Science.gov (United States)

    Song, Minsoo; Yoon, Tai Hyun

    2013-02-01

    We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s(2)(1)S0↔ 6s7s (1)S0) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm(3) and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s(1)S0 state via the intercombination 6s6p(3)P1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle. PMID:23464193

  19. Dynamic and unique nucleolar microenvironment revealed by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Park, Hweon; Han, Sung-Sik; Sako, Yasushi; Pack, Chan-Gi

    2015-03-01

    Organization and functions of the nucleolus is maintained by mobilities and interactions of nucleolar factors. Because the nucleolus is a densely packed structure, molecular crowding effects determined by the molecular concentrations and mobilities in the nucleolus should also be important for regulating nucleolar organization and functions. However, such molecular property of nucleolar organization is not fully understood. To understand the biophysical property of nucleolar organization, the diffusional behaviors of inert green fluorescent protein (GFP) oligomers with or without nuclear localization signals (NLSs) were analyzed under various conditions by fluorescence correlation spectroscopy. Our result demonstrates that the mobility of GFPs inside the nucleolus and the nucleoplasm can be represented by single free diffusion under normal conditions, even though the mobility in the nucleolus is considerably slower than that in the chromatin region. Moreover, the free diffusion of GFPs is found to be significantly size- and NLS-dependent only in the nucleolus. Interestingly, the mobility in the nucleolus is highly sensitive to ATP depletion, as well as actinomycin D (ActD) treatment. In contrast, the ultra-structure of the nucleolus was not significantly changed by ATP depletion but was changed by ActD treatment. These results suggest that the nucleolus behaves similarly to an open aqueous-phase medium with an increased molecular crowding effect that depends on both energy and transcription.

  20. Diagnosis of meningioma by time-resolved fluorescence spectroscopy.

    Science.gov (United States)

    Butte, Pramod V; Pikul, Brian K; Hever, Aviv; Yong, William H; Black, Keith L; Marcu, Laura

    2005-01-01

    We investigate the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as an adjunctive tool for the intraoperative rapid evaluation of tumor specimens and delineation of tumor from surrounding normal tissue. Tissue autofluorescence is induced with a pulsed nitrogen laser (337 nm, 1.2 ns) and the intensity decay profiles are recorded in the 370 to 500 nm spectral range with a fast digitizer (0.2 ns resolution). Experiments are conducted on excised specimens (meningioma, dura mater, cerebral cortex) from 26 patients (97 sites). Spectral intensities and time-dependent parameters derived from the time-resolved spectra of each site are used for tissue characterization. A linear discriminant analysis algorithm is used for tissue classification. Our results reveal that meningioma is characterized by unique fluorescence characteristics that enable discrimination of tumor from normal tissue with high sensitivity (>89%) and specificity (100%). The accuracy of classification is found to increase (92.8% cases in the training set and 91.8% in the cross-validated set correctly classified) when parameters from both the spectral and the time domain are used for discrimination. Our findings establish the feasibility of using TR-LIFS as a tool for the identification of meningiomas and enables further development of real-time diagnostic tools for analyzing surgical tissue specimens of meningioma or other brain tumors. PMID:16409091

  1. Evaluation of actinic cheilitis using fluorescence lifetime spectroscopy

    Science.gov (United States)

    Saito Nogueira, Marcelo; Cosci, Alessandro; Pratavieira, Sebastião.; Takahama, Ademar; Souza Azevedo, Rebeca; Kurachi, Cristina

    2016-03-01

    Actinic cheilitis is a potentially malignant disorder that mostly affects the vermilion border of the lower lip and can lead to squamous cell carcinoma. Because of its heterogeneous clinical aspect, it is difficult to indicate representative biopsy area. Late diagnosis is a limiting factor of therapeutic possibilities available to treat oral cancer. The diagnosis of actinic cheilitis is mainly based on clinical and histopathological analysis and it is a time consuming procedure to get the results. Information about the organization and chemical composition of the tissues can be obtained using fluorescence lifetime spectroscopy techniques without the need for biopsy. The main targeted fluorophores are NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), which have free and bound states, each one with different average lifetimes. The average lifetimes for free and bound NADH and FAD change according to tissue metabolic alterations and allow a quick and non-invasive clinical investigation of injuries and to help clinicians with the early diagnosis of actinic cheilitis. This study aims to evaluate the fluorescence lifetime parameters at the discrimination of three degrees of epithelial dysplasia, the most important predictor of malignant development, described in up to 100% of actinic cheilitis cases.

  2. Introducing many-body physics using atomic spectroscopy

    CERN Document Server

    Krebs, Dietrich; Santra, Robin

    2013-01-01

    Atoms constitute relatively simple many-body systems, making them suitable objects for developing an understanding of basic aspects of many-body physics. Photoabsorption spectroscopy is a prominent method to study the electronic structure of atoms and the inherent many-body interactions. In this article the impact of many-body effects on well-known spectroscopic features such as Rydberg series, Fano resonances, Cooper minima, and giant resonances is studied, and related many-body phenomena in other fields are outlined. To calculate photoabsorption cross sections the time-dependent configuration interaction singles (TDCIS) model is employed. The conceptual clearness of TDCIS in combination with the compactness of atomic systems allows for a pedagogical introduction to many-body phenomena.

  3. Laser sources for precision spectroscopy on atomic strontium

    OpenAIRE

    Poli, N.; Ferrari, G; Prevedelli, M.; Sorrentino, F.; Drullinger, R. E.; Tino, G. M.

    2006-01-01

    We present a new laser setup designed for high-precision spectroscopy on laser cooled atomic strontium. The system, which is entirely based on semiconductor laser sources, delivers 200 mW at 461 nm for cooling and trapping atomic strontium from a thermal source, 4 mW at 497 nm for optical pumping from the metastable View the MathML source state, 12 mW at 689 nm on linewidth less than 1 kHz for second-stage cooling of the atomic sample down to the recoil limit, 1.2 W at 922 nm for optical trap...

  4. High precision spectroscopy of pionic and antiprotonic atoms; Spectroscopie de precision des atomes pioniques et antiprotoniques

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, P

    1998-04-15

    The study of exotic atoms, in which an orbiting electron of a normal atom is replaced by a negatively charged particle ({pi}{sup -}, {mu}{sup -}, p, {kappa}{sup -}, {sigma}{sup -},...) may provide information on the orbiting particle and the atomic nucleus, as well as on their interaction. In this work, we were interested in pionic atoms ({pi}{sup -14} N) on the one hand in order to determine the pion mass with high accuracy (4 ppm), and on the other hand in antiprotonic atoms (pp-bar) in order to study the strong nucleon-antinucleon interaction at threshold. In this respect, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high stop density for particles in gas targets at low pressure. Using curved crystals, an extended X-ray source could be imaged onto the detector. Charge-Coupled Devices were used as position sensitive detectors in order to measure the Bragg angle of the transition to a high precision. The use of gas targets resolved the ambiguity owing to the number of K electrons for the value of the pion mass, and, for the first time, strong interaction shift and broadening of the 2p level in antiprotonic hydrogen were measured directly. (author)

  5. Titanium atom detection by resonance fluorescence excited with a nitrogen laser

    International Nuclear Information System (INIS)

    Coincidence of wave lengths of nitrogen laser basing lines and resonance transitions in titanium atom is investigated. It is shown that resonance fluorescence excited by nitrogen laser can be used for absolute titanium atom density measurements. Experiments on titanium atom detection in a vapour cloud formed under irradiation of a titanium target in vacuum by dye laser pulse, are conducted. Fluorescence extinguishing is observed under high evaporation power

  6. Spectroscopy of PTCDA attached to rare gas samples: clusters vs. bulk matrices. II. Fluorescence emission spectroscopy

    CERN Document Server

    Dvorak, M; Knoblauch, T; Bünermann, O; Rydlo, A; Minniberger, S; Harbich, W; Stienkemeier, F

    2012-01-01

    The interaction between PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. On the one hand, laser-excited PTCDA-doped large argon, neon and para-hydrogen clusters in comparison with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground state takes place. On the other hand, fluorescence emission studies of PTCDA embedded in bulk neon and argon matrices results in much more complex spectral signatures characterized by a splitting of the different emission lines. These can be assigned to the appearance of site isomers of the surrounding matrix lattice structure.

  7. Atomic jet with ionization detection for laser spectroscopy of Rydberg atoms under collisions and fields

    Science.gov (United States)

    Philip, G.

    2008-03-01

    An efficient atomic jet setup offering many unprecedented advantages over a conventional heat pipe setup used in multi-photon spectroscopy, mainly of alkaline-earth metals, has been constructed by a scheme in which the sample material is encapsulated in a disposable cartridge oven located inside a thermally stabilised heat-pipe and is made to effuse in to a row of atomic beams merging to form a jet target. This novel scheme combines the advantages of both high density atomic beam with convenient geometry for orthogonal excitation and high sensitive ionisation detection capabilities of thermionic diodes, besides eliminating several problems inherent in the usual heat-pipe operation. Out of various designs, typical results are presented for a linear heat-pipe with vertical atomic jet used in two-photon spectroscopy of highly excited states of Sr I. Controlled excitations of both Rydberg and non-Rydberg states, which cannot otherwise be accessed from the ground state due to parity and spectroscopic selection rules, have been achieved by employing a weak electric field complimented by collisions. The atomic jet setup is also found very useful for the study of collisional broadening and shift of excited states and time evolution of Rydberg atoms.

  8. Observation of Climacteric-Like Behavior of Citrus Leaves Using Fluorescence Spectroscopy

    Directory of Open Access Journals (Sweden)

    Caio B. Wetterich

    2014-01-01

    Full Text Available Observation of climacteric-like behavior in citrus leaves depends on the detection of ethylene. However, such detection requires a gas chromatographer and complex sample preparation procedures. In this work, fluorescence spectroscopy was investigated as a diagnostic technique for climacteric-like behavior in citrus leaves. Our results indicate that the chlorophyll fluorescence presents a time evolution consistent with the ethylene evolution. Therefore, fluorescence spectroscopy may be used to observe the climacteric-like behavior in citrus leaves.

  9. Laser cooling, trapping, and Rydberg spectroscopy of neutral holmium atoms

    Science.gov (United States)

    Hostetter, James Allen

    This thesis focuses on progress towards using ensembles of neutral holmium for use in quantum computing operations. We are particularly interested in using a switchable interaction between neutral atoms, the Rydberg blockade, to implement a universal set of quantum gates in a collective encoding scheme that presents many benefits over quantum computing schemes which rely on physically distinct qubits. We show that holmium is uniquely suited for operations in a collective encoding basis because it has 128 ground hyperfine states, the largest number of any stable, neutral atom. Holmium is a rare earth atom that is very poorly described for our purposes as it has never been cooled and trapped, its spectrum is largely unknown, and it presents several unique experimental challenges related to its complicated atomic structure and short wavelength transitions. We demonstrate important progress towards overcoming these challenges. We produce the first laser cooling and trapping of holmium into a MOT. Because we use a broad cooling transition, our cooling technique does not require the use of a Zeeman slower. Using MOT depletion spectroscopy, we provide precise measurements of holmium's Rydberg states and its ionization potential. Our work continues towards cooling holmium into a dipole trap by calculating holmium's AC polarizability and demonstrating the results of early attempts at an optical dipole trap. We provide details of future upgrades to the experimental apparatus and discuss interesting potential for using holmium in quantum computing using single atoms in a magnetically trapped lattice. This thesis shows several promising indicators for continued work in this field.

  10. Precision atomic beam density characterization by diode laser absorption spectroscopy

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10-5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 104 atoms cm-3. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  11. Excimer laser fragmentation fluorescence spectroscopy for real-time monitoring of combustion generated pollutants

    Science.gov (United States)

    Damm, Christopher John

    Toxic pollutant emissions from combustion pose a hazard to public and environmental health. Better diagnostic techniques would benefit emissions monitoring programs and aid research aimed at understanding toxic pollutant formation and behavior. Excimer Laser Fragmentation Fluorescence Spectroscopy (ELFFS) provides sensitive, real-time, in situ measurements of several important combustion related pollutants. This thesis demonstrates the capabilities of ELFFS for detecting amines in combustion exhausts and carbonaceous particulate matter from engines. ELFFS photofragments target species using a 193 nm excimer laser to form fluorescent signature species. The NH (A--X) band at 336 nm is used to monitor ammonia, ammonium nitrate and ammonium sulfate. There are no major interferences in this spectral region. The sensitivity is approximately 100 ppb (1 second measurement) for ammonia in post flame gases and 100 ppb (mole fraction) for ammonium nitrate/sulfate in ambient air. Quenching of NH by the major combustion products does not limit the applicability of the detection method. Fluorescence from excited carbon atoms at 248 nm (1P 0 → 1S0) following photofragmentation measures particulate matter in a two-stroke gasoline engine and a four-stroke diesel engine. Fluorescence from CH (A2Delta → X 2pi, 431 nm) C2 (d3pig → a3piu, 468 nm) fragments is also observed. The atomic carbon fluorescence signal is proportional to the mass concentration of particles in the laser interrogation region. The 100-shot (1 second) detection limit for particles in the two-stroke gasoline engine exhaust is 0.5 ppb (volume fraction). The 100-shot detection limit for four-stroke diesel particulate matter is 0.2 ppb. Interferences from carbon monoxide and carbon dioxide are negligible. The ratios of atomic carbon, C2, and CH peaks provide information on the molecular forms of compounds condensed on or contained within the particles measured. The C/C2 signal ratio can be used to distinguish

  12. Influence of angle's ranges for recording an X-ray fluorescence hologram on reconstructed atomic images

    Institute of Scientific and Technical Information of China (English)

    XIE Hong-Lan; CHEN Jian-Wen; GAO Hong-Yi; ZHU Hua-Feng; LI Ru-Xin; XU Zhi-Zhan

    2004-01-01

    X-ray fluorescence holography (XFH) is a novel method for three-dimensional (3D) imaging of atomic structure. Theoretically, in an XFH experiment, one has to measure the fluorescence energy on a spherical surface to get well-resolved 3D images of atoms. But in practice, the experimental system arrangement does not allow the measurement of the fluorescent intensity oscillations in the full sphere. The holographic information losses because of the limited sampling range (less than 4π) will directly result in defective reconstructed atomic images. In this work, the atomic image of a Fe single crystal (001) was reconstructed by numerically simulating X-ray fluorescence holograms of the crystal at different recording angle's ranges and step lengths. Influences of the ranges of azimuth angles and polar angles and the step length of polar angles on the reconstructed atomic images were discussed.

  13. Fluorescence spectroscopy: a powerful technique for the noninvasive characterization of artwork.

    Science.gov (United States)

    Romani, Aldo; Clementi, Catia; Miliani, Costanza; Favaro, Gianna

    2010-06-15

    After electronic excitation by ultraviolet or visible radiation, atoms and molecules can undergo thermal or radiative deactivation processes before relaxing to the ground state. They can emit photons with longer wavelengths than the incoming exciting radiation, that is, they can fluoresce in the UV-vis-near-infrared (NIR) range. The study of fluorescence relaxation processes is one of the experimental bases on which modern theories of atomic and molecular structure are founded. Over the past few decades, technological improvements in both optics and electronics have greatly expanded fluorimetric applications, particularly in analytical fields, because of the high sensitivity and specificity afforded by the methods. Using fluorimetry in the study and conservation of cultural heritage is a recent innovation. In this Account, we briefly summarize the use of fluorescence-based techniques in examining the constituent materials of a work of art in a noninvasive manner. Many chemical components in artwork, especially those of an organic nature, are fluorescent materials, which can be reliably used for both diagnostic and conservative purposes. We begin by examining fluorimetry in the laboratory setting, considering the organic dyes and inorganic pigments that are commonly studied. For a number of reasons, works of art often cannot be moved into laboratories, so we continue with a discussion of portable instruments and a variety of successful "field applications" of fluorimetry to works of cultural heritage. These examples include studies of mural paintings, canvas paintings, tapestries, and parchments. We conclude by examining recent advances in treating the data that are generated in fluorescence studies. These new perspectives are focused on the spectral shape and lifetime of the emitted radiation. Recent developments have provided the opportunity to use various spectroscopic techniques on an increasing number of objects, as well as the ability to fully characterize

  14. Investigation on the Photodissociation of Oxygen from Oxymyoglobin by Fluorescence Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hua-wei; CAO Hong-yu; TANG Qian; MA Jun-yan; ZHANG Ying-ying; ZHENG Xue-fang

    2011-01-01

    Photodissociation of oxygen from oxymyoglobin(oxyMb)was investigated by means of fluorescence spectroscopy.One of the most important findings of the photodissociation of oxyMb was the discovery of two processes which were affected by excitation intensity,temperature,solvent viscosity,and excitation wavelength.Process Ⅰ(PⅠ)corresponded to oxygen escaping from the binding site at ferrous heme iron atom within the porphyrin ring into the heme pocket,whereas process Ⅱ(PⅡ)was ascribed to oxygen escaping from the heme pocket into the solvent.To elucidate this interesting phenomenon,we proposed a model that oxygen encountered two barriers on its way from the binding site at the ferrous heme iron to the solvent.Reversibility and wavelength sensitivity of the photodissociation were also observed.

  15. Angular distribution and atomic effects in condensed phase photoelectron spectroscopy

    International Nuclear Information System (INIS)

    A general concept of condensed phase photoelectron spectroscopy is that angular distribution and atomic effects in the photoemission intensity are determined by different mechanisms, the former being determined largely by ordering phenomena such as crystal momentum conservation and photoelectron diffraction while the latter are manifested in the total (angle-integrated) cross section. In this work, the physics of the photoemission process is investigated in several very different experiments to elucidate the mechanisms of, and correlation between, atomic and angular distribution effects. Theoretical models are discussed and the connection betweeen the two effects is clearly established. The remainder of this thesis, which describes experiments utilizing both angle-resolved and angle-integrated photoemission in conjunction with synchrotron radiation in the energy range 6 eV less than or equal to h ν less than or equal to 360 eV and laboratory sources, is divided into three parts

  16. Atomic and Molecular Data for Optical Stellar Spectroscopy

    CERN Document Server

    Heiter, U; Asplund, M; Barklem, P S; Bergemann, M; Magrini, L; Masseron, T; Mikolaitis, Š; Pickering, J C; Ruffoni, M P

    2015-01-01

    High-precision spectroscopy of large stellar samples plays a crucial role for several topical issues in astrophysics. Examples include studying the chemical structure and evolution of the Milky Way galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Data are accumulating from instruments that obtain high-quality spectra of stars in the ultraviolet, optical and infrared wavelength regions on a routine basis. These instruments are located at ground-based 2- to 10-m class telescopes around the world, in addition to the spectrographs with unique capabilities available at the Hubble Space Telescope. The interpretation of these spectra requires high-quality transition data for numerous species, in particular neutral and singly ionized atoms, and di- or triatomic molecules. We rely heavily on the continuous efforts of laboratory astrophysics groups that produce and improve the relevant experimental and theoretical atomic and molecular data. The compilation of the best available ...

  17. Laser sources for precision spectroscopy on atomic strontium

    OpenAIRE

    Ferrari, G; T.M. Brzozowski; R. DRULLINGER; Poli, N.; Prevedelli, M.; Toninelli, C.; Tino, G. M.

    2004-01-01

    Laser Optics 2003: Solid State Lasers and Nonlinear Frequency Conversion, edited by Vladimir I. Ustugov abstract: We present a new laser setup suited for high precision spectroscopy on atomic strontium. The source is used for an absolute frequency measurement of the visible 5s21S0-5s5p3P1 intercombination line of strontium which is considered a possible candidate for a future optical frequency standard. The optical frequency is measured with an optical comb generator referenced to the SI t...

  18. Resonantly enhanced Bragg-scattering spectroscopy of an atomic transition

    Science.gov (United States)

    Yang, Xudong; Qiao, Cuifang; Li, Chuanliang; Chen, Fenghua

    2016-07-01

    A novel resonantly enhanced Bragg-scattering (REBS) spectroscopy from a population difference grating (PDG) is reported. The PDG is formed by a standing-wave (SW) pump field, which periodically modulates the space population distributions of two levels in the 87Rb D1 line. Then, a probe beam, having identical frequency and orthogonal polarization with the SW pump field, is Bragg-scattered by the PDG. The research achievement shows that the Bragg-scattered light is strongest at an atomic transition, and forms an REBS spectrum with a high signal-to-noise ratio and sub-natural linewidth. The observed REBS can be applied in precise frequency measurements.

  19. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    International Nuclear Information System (INIS)

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of Kα and Kβ emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS

  20. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin [Univ. of California, Davis, CA (United States). Dept. of Applied Science

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  1. Atomic Spectroscopy and Collisions Using Slow Antiprotons \\\\ ASACUSA Collaboration

    CERN Multimedia

    Matsuda, Y; Lodi-rizzini, E; Kuroda, N; Schettino, G; Hori, M; Pirkl, W; Mascagna, V; Malbrunot, C L S; Yamazaki, Y; Eades, J; Simon, M; Massiczek, O; Sauerzopf, C; Breuker, H; Nagata, Y; Uggerhoj, U I; Mc cullough, R W; Toekesi, K M; Venturelli, L; Widmann, E; Zmeskal, J; Kanai, Y; Hayano, R; Knudsen, H; Kristiansen, H; Todoroki, K; Bartel, M A; Moller, S P; Charlton, M; Leali, M; Diermaier, M; Kolbinger, B

    2002-01-01

    ASACUSA (\\underline{A}tomic \\underline{S}pectroscopy \\underline{A}nd \\underline{C}ollisions \\underline{U}sing \\underline{S}low \\underline{A}ntiprotons) is a collaboration between a number of Japanese and European research institutions, with the goal of studying bound and continuum states of antiprotons with simple atoms.\\\\ Three phases of experimentation are planned for ASACUSA. In the first phase, we use the direct $\\overline{p}$ beam from AD at 5.3 MeV and concentrate on the laser and microwave spectroscopy of the metastable antiprotonic helium atom, $\\overline{p}$He$^+$, consisting of an electron and antiproton bound by the Coulomb force to the helium nucleus. Samples of these are readily created by bringing AD antiproton beam bunches to rest in helium gas. With the help of techniques developed at LEAR for resonating high precision laser beams with antiproton transitions in these atoms, ASACUSA achieved several of these first-phase objectives during a few short months of AD operation in 2000. Six atomic tr...

  2. Laser sources for precision spectroscopy on atomic strontium.

    Science.gov (United States)

    Poli, N; Ferrari, G; Prevedelli, M; Sorrentino, F; Drullinger, R E; Tino, G M

    2006-04-01

    We present a new laser setup designed for high-precision spectroscopy on laser cooled atomic strontium. The system, which is entirely based on semiconductor laser sources, delivers 200 mW at 461 nm for cooling and trapping atomic strontium from a thermal source, 4 mW at 497 nm for optical pumping from the metastable P23 state, 12 mW at 689 nm on linewidth less than 1 kHz for second-stage cooling of the atomic sample down to the recoil limit, 1.2 W at 922 nm for optical trapping close to the "magic wavelength" for the 0-1 intercombination line at 689 nm. The 689 nm laser was already employed to perform a frequency measurement of the 0-1 intercombination line with a relative accuracy of 2.3 x 10(-11), and the ensemble of laser sources allowed the loading in a conservative dipole trap of multi-isotopes strontium mixtures. The simple and compact setup developed represents one of the first steps towards the realization of a transportable optical standards referenced to atomic strontium. PMID:16527534

  3. Fluorescence Correlation Spectroscopy and Nonlinear Stochastic Reaction-Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Del Razo, Mauricio; Pan, Wenxiao; Qian, Hong; Lin, Guang

    2014-05-30

    The currently existing theory of fluorescence correlation spectroscopy (FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde [Biopolymers (1974) 13:1-27]. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems there are no closed solutions; therefore, stochastic Monte-Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Extending Delbrück-Gillespie’s theory for stochastic nonlinear reactions with rapidly stirring to reaction-diffusion systems provides a mesoscopic model for chemical and biochemical reactions at nanometric and mesoscopic level such as a single biological cell.

  4. Fluorescence lifetime spectroscopy for breast cancer margins assessment

    Science.gov (United States)

    Gorpas, Dimitris; Fatakdawala, Hussain; Zhang, Yanhong; Bold, Richard; Marcu, Laura

    2015-03-01

    During breast conserving surgery (BCS), which is the preferred approach to treat most early stage breast cancers, the surgeon attempts to excise the tumor volume, surrounded by thin margin of normal tissue. The intra-operative assessment of cancerous areas is a challenging procedure, with the surgeon usually relying on visual or tactile guidance. This study evaluates whether time-resolved fluorescence spectroscopy (TRFS) presents the potential to address this problem. Point TRFS measurements were obtained from 19 fresh tissue slices (7 patients) and parameters that characterize the transient signals were quantified via constrained least squares deconvolution scheme. Fibrotic tissue (FT, n=69), adipose tissue (AT, n=76), and invasive ductal carcinoma (IDC, n=27) were identified in histology and univariate statistical analysis, followed by multi-comparison test, was applied to the corresponding lifetime data. Significant differentiation between the three tissue types exists at 390 nm and 500 nm bands. The average lifetime is 3.23+/-0.74 ns for AT, 4.21+/-0.83 ns for FT and 4.71+/-0.35 ns (ptissue in real-time and assess tumor margins.

  5. Production of ultra slow antiprotons, its application to atomic collisions and atomic spectroscopy - ASACUSA project

    International Nuclear Information System (INIS)

    The Atomic Spectroscopy And Collisions Using Slow Antiprotons (ASACUSA) project aims at studying collision dynamics with slow antiprotons and high precision spectroscopy of antiprotonic atoms. To realize these purposes, the production of high quality ultra slow antiproton beams is essential, which is achieved by the combination of antiproton decelerator (AD) from 3 GeV to 5 MeV, a radio frequency quadrupole (RFQ) decelerator from 5 MeV to 50 keV, and finally an electromagnetic trap from 50 keV to 10 eV. From the atomic physics point of view, an antiproton is an extremely heavy electron and/or a negatively charged proton, i.e., the antiproton is a unique tool to shed light on collision dynamics from the other side of the world. In addition to this fundamentally important feature, the antiproton has also a big practical advantage, i.e., it annihilates with the target nuclei emitting several energetic pions, which provides high detection efficiency with very good time resolution. Many-body effects which are of great importance to several branches of science will be studied through ionization and antiprotonic atom formation processes under single collision conditions. Various antiprotonic atoms including protonium (p anti-p) are expected to be meta-stable in vacuum, which is never true for those in dense media except for antiprotonic helium. High precision spectroscopy of protonium will for the first time become feasible benefited by this meta-stability. The present review reports briefly the production scheme of ultra slow antiproton beams and several topics proposed in the ASACUSA project

  6. Atomic spectroscopy sympsoium, Gaithersburg, Maryland, September 23--26, 1975. [Program, abstracts, and author index

    Energy Technology Data Exchange (ETDEWEB)

    1975-01-01

    Abstracts of one hundred papers given at the conference are presented along with the conference program and an author index. Session topics include: highly ionized atoms; laser spectroscopy and hyperfine structure; complex spectra; laser spectroscopy, radiation theory; theory of highly ionized atoms and analysis of plasmas; plasma spectroscopy, line strengths; spectral analysis, instrumentation, reference wavelengths; beam foil spectroscopy, line strengths, energy levels; absorption spectroscopy, autoionization, and related theory; and spectral analysis, instrumentation, and VUV physics. (GHT)

  7. Plasmonic antennas and zero mode waveguides to enhance single molecule fluorescence detection and fluorescence correlation spectroscopy towards physiological concentrations

    CERN Document Server

    Punj, Deep; Moparthi, Satish Babu; de Torres, Juan; Grigoriev, Victor; Rigneault, Hervé; Wenger, Jérôme

    2014-01-01

    Single-molecule approaches to biology offer a powerful new vision to elucidate the mechanisms that underpin the functioning of living cells. However, conventional optical single molecule spectroscopy techniques such as F\\"orster fluorescence resonance energy transfer (FRET) or fluorescence correlation spectroscopy (FCS) are limited by diffraction to the nanomolar concentration range, far below the physiological micromolar concentration range where most biological reaction occur. To breach the diffraction limit, zero mode waveguides and plasmonic antennas exploit the surface plasmon resonances to confine and enhance light down to the nanometre scale. The ability of plasmonics to achieve extreme light concentration unlocks an enormous potential to enhance fluorescence detection, FRET and FCS. Single molecule spectroscopy techniques greatly benefit from zero mode waveguides and plasmonic antennas to enter a new dimension of molecular concentration reaching physiological conditions. The application of nano-optics...

  8. Search for ultralight scalar dark matter with atomic spectroscopy

    CERN Document Server

    Van Tilburg, Ken; Bougas, Lykourgos; Budker, Dmitry

    2015-01-01

    We report new limits on ultralight scalar dark matter (DM) with dilaton-like couplings to photons that can induce oscillations in the fine-structure constant alpha. Atomic dysprosium exhibits an electronic structure with two nearly degenerate levels whose energy splitting is sensitive to changes in alpha. Spectroscopy data for two isotopes of dysprosium over a two-year span is analyzed for coherent oscillations with angular frequencies below 1 rad/s. No signal consistent with a DM coupling is identified, leading to new constraints on dilaton-like photon couplings over a wide mass range. Under the assumption that the scalar field comprises all of the DM, our limits on the coupling exceed those from equivalence-principle tests by up to 4 orders of magnitude for masses below 3 * 10^-18 eV. Excess oscillatory power, inconsistent with fine-structure variation, is detected in a control data set, and is likely due to a systematic effect. Our atomic spectroscopy limits on DM are the first of their kind, and leave sub...

  9. Atomic spectroscopy and highly accurate measurement: determination of fundamental constants

    International Nuclear Information System (INIS)

    This document reviews the theoretical and experimental achievements of the author concerning highly accurate atomic spectroscopy applied for the determination of fundamental constants. A pure optical frequency measurement of the 2S-12D 2-photon transitions in atomic hydrogen and deuterium has been performed. The experimental setting-up is described as well as the data analysis. Optimized values for the Rydberg constant and Lamb shifts have been deduced (R = 109737.31568516 (84) cm-1). An experiment devoted to the determination of the fine structure constant with an aimed relative uncertainty of 10-9 began in 1999. This experiment is based on the fact that Bloch oscillations in a frequency chirped optical lattice are a powerful tool to transfer coherently many photon momenta to the atoms. We have used this method to measure accurately the ratio h/m(Rb). The measured value of the fine structure constant is α-1 = 137.03599884 (91) with a relative uncertainty of 6.7*10-9. The future and perspectives of this experiment are presented. This document presented before an academic board will allow his author to manage research work and particularly to tutor thesis students. (A.C.)

  10. Noninvasive skin fluorescence spectroscopy for detection of abnormal glucose tolerance

    Directory of Open Access Journals (Sweden)

    Edward L. Hull, PhD

    2014-09-01

    Full Text Available The ENGINE study evaluated noninvasive skin fluorescence spectroscopy (SFS for detection of abnormal glucose tolerance (AGT. The AGT detection performance of SFS was compared to fasting plasma glucose (FPG and hemoglobin A1C (A1C. The study was a head-to-head comparison of SFS to FPG and A1C in an at-risk population of 507 subjects, with no prior diagnosis of diabetes, each of whom received a 75 g, two-hour oral glucose tolerance test (OGTT. Subjects were measured by SFS on multiple days in fasting and non-fasting states. SFS data were acquired and analyzed with the SCOUT DS® device (VeraLight, Albuquerque, NM, USA. Disease truth was AGT, defined as OGTT ≥ 7.8 mmol/L. Sensitivity, false positive rate (FPR, ROC area, and equal error rate (EER for detection of AGT were computed. The reproducibility of SFS and FPG was assessed. The AGT sensitivity of SFS at the device's recommended screening threshold of 50 was 75.2%, higher than that of FPG (thresholds of 5.6 mmol/L or 6.1 mmol/L and A1C (thresholds of 5.7% or 6.0%. The SFS FPR was 42.1%, comparable to an A1C threshold of 5.7% (FPR = 43.5%. The EERs of SFS, FPG and A1C were similar, as were the partial ROC areas for FPRs of 20–50%. The reproducibility of SFS was 7.7% versus 8.1% for FPG. SFS had similar AGT detection performance to FPG and A1C and is a viable alternative to screening individuals for AGT.

  11. Laser-induced Fluorescence Spectroscopy for applications in chemical sensing and optical refrigeration

    Science.gov (United States)

    Kumi Barimah, Eric

    Laser-induced breakdown spectroscopy (LIBS) is an innovative technique that has been used as a method for fast elemental analysis in real time. Conventional ultraviolet-visible (UV-VIS) LIBS has been applied to detect the elemental composition of different materials, including explosives, pharmaceutical drugs, and biological samples. The extension of conventional LIBS to the infrared region (˜1-12 mum) promises to provide additional information on molecular emission signatures due to rotational-vibrational transitions. In this research, a pulsed Nd: YAG laser operating at 1064 nm was focused onto several sodium compounds (NaCl, NaClO3, Na2CO3 and NaClO4) and potassium compounds (KCl, KClO3, K2CO3 and KClO4) to produce an intense plasma at the target surface. Several distinct infrared (IR) atomic emission signatures were observed from all sodium and potassium containing compounds. The atomic emission lines observed from the investigated samples matched assigned transitions of neutral sodium and potassium atoms published in the National Institute of Standards and Technology (NIST) atomic database. In addition to the intense atomic lines, the rst evidence of molecular LIBS emission structures were observed at ˜10.0 m in KClO3 and NaClO3 for the chlorate anion (ClO3 --1), at ˜6.7 to 8.0 mum in KNO3 and NaNO 3 for the nitrate anion (NO3--1 ), ˜8.0 to 10.0 mum in KClO4 and NaClO4 for perchlorate anion (ClO4--1 ), and ˜6.88 mum and 11.53 mum in Na2CO3 for the carbonate anion (CO3--1 ). The observed molecular emission showed strong correlation with the conventional Fourier Transform Infrared Spectrometry (FTIR) absorption spectra of the investigated samples. IR LIBS was also applied to determine the limit of detection (LOD) for the perchlorate anion in KClO4 using the 8.0 -11.0 mum IR-LIBS emission band. The calibration curve of ClO4 in KClO4 was constructed using peak and integrated emission intensities for known concentrations of mixed KClO4/NH4NO3 samples. The

  12. Assessing topographic cutaneous autofluorescence variation using fluorescence UV and visible excitation emission matrix (EEM) spectroscopy

    Science.gov (United States)

    Zhao, Jianhua; Zandi, Soodabeh; Feng, Florina; Zeng, Haishan; McLean, David I.; Lui, Harvey

    2011-03-01

    Cutaneous autofluorescence properties were systematically studied using fluorescence excitation emission matrix spectroscopy. Twenty-six healthy subjects with a mean age of 34 (range 21-74) participated in this study. The fluorescence of major skin fluorophores such as tryptophan, collagen, elastin and NADH could be readily identified. On average, facial skin shows strong tryptophan and measurable porphyrin fluorescence; the palm and nail show strong tryptophan and keratin fluorescence. These results demonstrate that regional topographic variations exist not only in the amount of fluorescence but also in the relative distribution of fluorophores in normal skin. Moreover this provides a basis for future interpretation of autofluorescence in diseased skin.

  13. Characterization of coal oil using three-dimensional excitation and emission matrix fluorescence spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Xue Xiao; Yujun Zhang; Zhigang Wang; Dan Jin; Gaofang Yin; Wenqing Liu

    2009-01-01

    Three-dimensioned (3D) excitation-emission matrix (EEM) fluorescence spectroscopy is applied to charac terize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly have one broad peak. This peak is identified at the excitation/emission wavelengths of 270/290 nm. The relation between the fluorescence intensity and the concentration of coal oil is also studied. When the concentration lies between 2 鈥? 2000 ppm, the relation between the fluorescence intensity and the concen tration of coal oil is well linear. The nature of solvents significantly affects the EEM fluorescence of coal oil.

  14. Cooperative Fluorescence from a Strongly Driven Dilute Cloud of Atoms

    OpenAIRE

    Ott, Johan Raunkjær; Wubs, Martijn; Lodahl, Peter; Mortensen, N. Asger; Kaiser, R.

    2013-01-01

    We investigate cooperative fluorescence in a dilute cloud of strongly driven two-level emitters. Starting from the Heisenberg equations of motion, we compute the first-order scattering corrections to the saturation of the excited-state population and to the resonance-fluorescence spectrum, which both require going beyond the state-of-the-art linear-optics approach to describe collective phenomena. A dipole blockade is observed due to long-range dipole-dipole coupling that vanishes at stronger...

  15. Optical resonance shifts in the fluorescence imaging of thermal and cold Rubidium atomic gases

    CERN Document Server

    Jenkins, S D; Javanainen, J; Bourgain, R; Jennewein, S; Sortais, Y R P; Browaeys, A

    2016-01-01

    We show that the resonance shifts in fluorescence of a cold gas of rubidium atoms substantially differ from those of thermal atomic ensembles that obey the standard continuous medium electrodynamics. The analysis is based on large-scale microscopic numerical simulations and experimental measurements of the resonance shifts in a steady-state response in light propagation.

  16. Novel laser atomic fluorescence spectrometer for environmental and biomedical analyses of heavy metals

    Science.gov (United States)

    Dergachev, Alex Y.; Mirov, Sergey B.; Pitt, Robert E.; Parmer, Keith D.

    1997-05-01

    We report on the development of a novel experimental set-up using laser atomic fluorescence for detection and concentration measurements of heavy metal atoms for environmental and biomedical analyses. This spectrometer is based on the application of tunable LiF:F2+** and LiF:F2- color center and alexandrite lasers with nonlinear converters for narrowband excitation of atomic fluorescence and the use of gated multichannel CCD detectors for fluorescence measurements. A standard graphite furnace module was used for sample atomization. The laser sources used provide narrowband selective laser excitation continuously tunable in the 200 - 400 nm range and are therefore suitable for resonant excitation of atomic transitions in practically all known heavy metal atoms. In the first experiments, water samples containing Cu, Pb and Fe impurities were studied and detection levels of less than 1 ppb were observed. Comparison of the results of atomic laser fluorescence analysis and traditional atomic absorption spectrometry showed good qualitative agreement between these two methods. It is projected that full optimization of our experimental set up will allow for improved detection levels of several orders of magnitude. Possible optimization and simplification of the spectrometer are discussed in the context of developing a portable instrument for field use.

  17. Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy

    Science.gov (United States)

    Li, Gaoming; Gao, Fei; Qiu, Yishen; Feng, Xiaohua; Zheng, Yuanjin

    2016-07-01

    Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.

  18. Excitation-emission matrices and synchronous fluorescence spectroscopy for the diagnosis of gastrointestinal cancers

    Science.gov (United States)

    Genova, Ts; Borisova, E.; Penkov, N.; Vladimirov, B.; Zhelyazkova, A.; Avramov, L.

    2016-06-01

    We report the development of an improved fluorescence technique for cancer diagnostics in the gastrointestinal tract. We investigate the fluorescence of ex vivo colorectal (cancerous and healthy) tissue samples using excitation-emission matrix (EEM) and synchronous fluorescence spectroscopy (SFS) steady-state approaches. The obtained results are processed for revealing characteristic fluorescence spectral features with a valuable diagnostic meaning. The main tissue fluorophores, contributing to the observed fluorescence, are tyrosine, tryptophan, NADH, FAD, collagen and elastin. Based on the results of the Mann-Whitney test as useful parameters for differentiation of gastrointestinal cancer from normal mucosa, we suggest using excitation wavelengths in the range 300 - 360 nm for fluorescence spectroscopy and wavelengths intervals of 60 nm and 90 nm for SFS.

  19. A double-well atom trap for fluorescence detection at the Heisenberg limit

    CERN Document Server

    Stroescu, Ion; Oberthaler, Markus K

    2014-01-01

    We experimentally demonstrate an atom number detector capable of simultaneous detection of two mesoscopic ensembles with single atom resolution. Such a sensitivity is a prerequisite for going beyond quantum metrology with spin-squeezed states. Our system is based on fluorescence detection of atoms in a novel hybrid trap in which a dipole barrier divides a magneto-optical trap into two separated wells. We introduce a noise model describing the various sources contributing to the measurement error and report a limit of up to 500 atoms for the exact determination of the atom number difference.

  20. Resonance fluorescence of a cold atom in a high-finesse resonator

    CERN Document Server

    Bienert, M; Torres, J M; Zippilli, S; Bienert, Marc; Morigi, Giovanna; Zippilli, Stefano

    2007-01-01

    We study the spectra of emission of a system composed by an atom, tightly confined inside a high-finesse resonator, when the atom is driven by a laser and is at steady state of the cooling dynamics induced by laser and cavity field. In general, the spectrum of resonance fluorescence and the spectrum at the cavity output contain complementary information about the dynamics undergone by the system. In certain parameter regimes, quantum interference effects between the scattering processes induced by cavity and laser field lead to the selective suppression of features of the resonance fluorescence spectrum, which are otherwise visible in the spectrum of laser-cooled atoms in free space.

  1. Tryptophan content for monitoring breast cancer cell aggressiveness by native fluorescence spectroscopy

    Science.gov (United States)

    Zhang, Lin; Pu, Yang; Xue, Jianpeng; Pratavieira, Sebastião.; Xu, Baogang; Achilefu, Samuel; Alfano, R. R.

    2014-03-01

    This study shows tryptophan as the key native marker in cells to determine the level of aggressive cancer in breast cell lines using native fluorescence spectroscopy. An algorithm based on the ratio of tryptophan fluorescence intensity at 340 nm to intensity at 460 nm is associated with aggressiveness of the cancer cells. The higher the ratio is, the more aggressive the tumor towards metastasis.

  2. Endogenous synchronous fluorescence spectroscopy (SFS) of basal cell carcinoma-initial study

    Science.gov (United States)

    Borisova, E.; Zhelyazkova, Al.; Keremedchiev, M.; Penkov, N.; Semyachkina-Glushkovskaya, O.; Avramov, L.

    2016-01-01

    The human skin is a complex, multilayered and inhomogeneous organ with spatially varying optical properties. Analysis of cutaneous fluorescence spectra could be a very complicated task; therefore researchers apply complex mathematical tools for data evaluation, or try to find some specific approaches, that would simplify the spectral analysis. Synchronous fluorescence spectroscopy (SFS) allows improving the spectral resolution, which could be useful for the biological tissue fluorescence characterization and could increase the tumour detection diagnostic accuracy.

  3. [Determination of potassium in sodium by flame atomic emission spectroscopy].

    Science.gov (United States)

    Xie, C; Wen, X; Jia, Y; Sun, S

    2001-06-01

    Sodium is used as a coolant in China experiment fast reactor (CEFR). Potassium in sodium has an influence on heat property of reactor. A analytical method has been developed to determinate potassium in sodium by flame atomic emission spectroscopy. Sodium sample is dissolved by ultrasonic humidifier. The working conditions of the instrument and inTerferences from matrix sodium, acid effect and concomitant elements have been studied. Standard addition experiments are carried out with potassium chloride. The percentage recoveries are 94.7%-109.8%. The relative standard deviation is 4.2%. The analytical range accords with sodium quality control standard of CFFR. The precision corresponds to the international analytical method in sodium coolant reactor. PMID:12947670

  4. Modulation transfer spectroscopy in a lithium atomic vapor cell.

    Science.gov (United States)

    Sun, Dali; Zhou, Chao; Zhou, Lin; Wang, Jin; Zhan, Mingsheng

    2016-05-16

    We have investigated modulation transfer spectroscopy of D2 transitions of 7Li atoms in a vapor cell. The role of the intensity of the probe beam in the spectrum is important, we have seen unique characteristics of the signal in the crossover peak. In order to find the best signal for laser locking, the slope and frequency offset of the zero-crossing signal are determined. The dependence of the modulation transfer spectra on polarizations of pump and probe beam is demonstrated. The residual amplitude modulation in the system is also considered, and the distortion of the spectra due to the modulation is analyzed. It was found that the crossover peak is more suitable for frequency stabilization due to its better residual amplitude modulation compensation. PMID:27409886

  5. Single gold nanoparticles to enhance the detection of single fluorescent molecules at micromolar concentration using fluorescence correlation spectroscopy

    Science.gov (United States)

    Punj, Deep; Rigneault, Hervé; Wenger, Jérôme

    2014-05-01

    Single nanoparticles made of noble metals are strongly appealing to develop practical applications to detect fluorescent molecules in solution. Here, we detail the use of a single gold nanoparticle of 100 nm diameter to enhance the detection of single Alex Fluor 647 fluorescent molecules at high concentrations of several micromolar. We discuss the implementation of fluorescence correlation spectroscopy, and provide a new method to reliably extract the enhanced fluorescence signal stemming from the nanoparticle near-field from the background generated in the confocal volume. The applicability of our method is checked by reporting the invariance of the single molecule results as function of the molecular concentration, and the experimental data is found in good agreement with numerical simulations.

  6. Optical spectroscopy of a highly fluorescent aggregate of bacteriochlorophyll c

    Science.gov (United States)

    Causgrove, T. P.; Cheng, P.; Brune, D. C.; Blankenship, R. E.

    1993-01-01

    Bacteriochlorophyll (BChl) c and a similar model compound, Mg-methyl bacteriopheophorbide d, form several types of aggregates in nonpolar solvents. One of these aggregates is highly fluorescent, with a quantum yield higher than that of the monomer. This aggregate is also unusual in that it shows a rise time in its fluorescence emission decay at certain wavelengths, which is ascribed to a change in conformation of the aggregate. An analysis of fluorescence depolarization data is consistent with either a linear aggregate of four or five monomers or preferably a cyclic arrangement of three dimers.

  7. Synchrotron radiation induced fluorescence spectroscopy of gas phase molecules

    OpenAIRE

    Álvarez Ruiz, Jesús

    2004-01-01

    A new experimental set-up for gas phase fluorescence studies using synchrotron radiation has been designed and constructed to perform simultaneously total and dispersed fluorescence measurements. Neutral photodissociation of CO has been investigated after excitation with 19-26 eV photons. Fluorescence from 3p 3P, 3p 3S and 3p 1D excited states in carbon was recorded and interpreted by ab initio calculations. The population and dissociation of states belonging to the C and D Rydberg series in ...

  8. Atoms, molecules and optical physics 1. Atomic physics and foundations of spectroscopy

    International Nuclear Information System (INIS)

    Unique, unified presentation of these partial fields and by this exclusive. With the highly reputed co-author Prof. Dr. Ingolf Volker Hertel. Eminent presentation makes it possible, together also over set connections. For bachelor/master and diploma curricula. The book applies primarily to graduate students of physics and physical chemistry until promotion. It offers a detailed introduction to the most important theme complexes of atomic and molecular physics and the methods of modern optical physics connected with this. In many selected partial fields it leads until the actual status of research. Simultaneously it also appeals to the active scientist and wants to be a standard work of the field. By the clearly stuctured chapters the reader is - starting from the foundations of quantum physics - step-wise made familiar with the most important phenomena and models of atomic and molecular physics and led wherever it is offered, to their actual developments in modern research. In the first part here present the to a certain degree canonical knowledge with the main topic structure of atoms and molecules and the competent spectroscopy is summarized. In the second part still being in work deepening knowledge for this is mediated, and selected chapters of modern optics, lase physics, cluster research, and scattering physics is treated, as well a short excursus in the world of cold atoms and molecules is given. At the whole both volumes of this textbook want to show to the interested reader that atomic, molecular, and optical physics, are still as usual an alive field of modern physical research

  9. Ultimate Statistical Physics: fluorescence of a single atom

    CERN Document Server

    Pomeau, Yves; Ginibre, Jean

    2016-01-01

    We discuss the statistics of emission of photons by a single atom or ion illuminated by a laser beam at the frequency of quasi-resonance between two energy levels, a situation that corresponds to real experiments. We extend this to the case of two laser beams resonant with the energy differences between two excited levels and the ground state (three level atom in V-configuration). We use a novel approach of this type of problem by considering Kolmogorov equation for the probability distribution of the atomic state which takes into account first the deterministic evolution of this state under the effect of the incoming laser beam and the random emission of photons during the spontaneous decay of the excited state(s) to the ground state. This approach yields solvable equations in the two level atom case. For the three level atom case we set the problem and define clearly its frame. The results obtained are valid both in the opposite limits of rare and of frequent spontaneous decay, compared to the period of the...

  10. Anabaena cell ageing monitored with confocal fluorescence spectroscopy.

    Science.gov (United States)

    Ke, Shan; Bindokas, Vytas; Haselkorn, Robert

    2015-01-01

    Cyanobacteria use a sophisticated system of pigments to collect light energy across the visible spectrum for photosynthesis. The pigments are assembled in structures called phycobilisomes, composed of phycoerythrocyanin, phycocyanin and allophycocyanin, which absorb energy and transfer it to chlorophyll in photosystem II reaction centres. All of the components of this system are fluorescent, allowing sensitive measurements of energy transfer using single cell confocal fluorescence microscopy. The native pigments can be interrogated without the use of reporters. Here, we use confocal fluorescence microscopy to monitor changes in the efficiency of energy transfer as single cells age, between the time they are born at cell division until they are ready to divide again. Alteration of fluorescence was demonstrated to change with the age of the cyanobacterial cell.

  11. Excitation emission and time-resolved fluorescence spectroscopy of selected varnishes used in historical musical instruments.

    Science.gov (United States)

    Nevin, Austin; Echard, Jean-Philippe; Thoury, Mathieu; Comelli, Daniela; Valentini, Gianluca; Cubeddu, Rinaldo

    2009-11-15

    The analysis of various varnishes from different origins, which are commonly found on historical musical instruments was carried out for the first time with both fluorescence excitation emission spectroscopy and laser-induced time-resolved fluorescence spectroscopy. Samples studied include varnishes prepared using shellac, and selected diterpenoid and triterpenoid resins from plants, and mixtures of these materials. Fluorescence excitation emission spectra have been collected from films of naturally aged varnishes. In parallel, time-resolved fluorescence spectroscopy of varnishes provides means for discriminating between short- (less than 2.0 ns) and long-lived (greater than 7.5 ns) fluorescence emissions in each of these complex materials. Results suggest that complementary use of the two non destructive techniques allows a better understanding of the main fluorophores responsible for the emission in shellac, and further provides means for distinguishing the main classes of other varnishes based on differences in fluorescence lifetime behaviour. Spectrofluorimetric data and time resolved spectra presented here may form the basis for the interpretation of results from future in situ fluorescence examination and time resolved fluorescence imaging of varnished musical instruments.

  12. Multiplexed fluorescence lifetime measurements by frequency-sweeping Fourier spectroscopy

    OpenAIRE

    Zhao, Ming; Peng, Leilei

    2010-01-01

    We report simultaneous measurements of fluorescence lifetimes at multiple excitation wavelengths with a Fourier transform frequency domain fluorescence lifetime spectrometer. The spectrometer uses a Michelson interferometer with its differential optical path length scanning at 22,000 Hz scan rate. The scan speed of the optical delay varies linearly during each scan and creates interference modulations that sweep from −150 to 150 MHz in 45.5 μs. The frequency-sweeping modulation allows nanosec...

  13. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

    Science.gov (United States)

    Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'Skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-06-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom-atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0-3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time.

  14. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

    CERN Document Server

    Okaba, Shoichi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-01-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturisation. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kKagome-lattice hollow-core photonic crystal fibre (HC-PCF) are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom-atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the $^1 S_0-{}^3P_1$ (m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibresHC-PCFs improve the optical depth while preserving atomic coherence time.

  15. [Laser-time-resolved fluorescence spectroscopy in immunoassays].

    Science.gov (United States)

    Pan, L; Du, J; Xie, W; Du, Q; Yun, Q

    2000-06-01

    This paper described a laser-excited time-resolved fluoroimmunoassay set. It made lanthanide ion to couple the anhydrde of diethylenetriaminepentaacetic acid (DTPAA) for labeling antibodies. The experiment used polystyrene tap coated with HCV antigen as the solid phase and a chelate of the rare earth metal europium as fluorescent label. A nitrogen laser beam was used to excite the Eu3- chelates and after 60 microseconds delay time, the emission fluorescence was measured. Background fluorescence of short lifetimes caused by serum components and Raman scattering can be eliminated by set the delay time. In the system condition, fluorescent spectra and fluorescent lifetimes of Eu3+ beta-naphthoyltrifluroacetone (NTA) chelates were measured. The fluorescent lifetime value is 650 microseconds. The maximum emission wavelength is 613 nm. The linear range of europium ion concentration is 1 x 10(-7)-1 x 10(-11) g.mL-1 and the detection limit is 1 x 10(-13) g.mL-1. The relative standard deviation of determination (n = 12) for samples at 0.01 ng.mL-1 magnitude is 6.4%. Laser-TRFIA was also found to be suitable for diagnosis of HCV. The sensitivity and specificity were comparable to enzyme immunoassay. The result was obtained with laser-TRFIA for 29 human correlated well with enzyme immunoassay. PMID:12958930

  16. Elasticity Maps of Living Neurons Measured by Combined Fluorescence and Atomic Force Microscopy

    CERN Document Server

    Spedden, Elise; Naumova, Elena N; Kaplan, David L; Staii, Cristian

    2013-01-01

    Detailed knowledge of mechanical parameters such as cell elasticity, stiffness of the growth substrate, or traction stresses generated during axonal extensions is essential for understanding the mechanisms that control neuronal growth. Here we combine Atomic Force Microscopy based force spectroscopy with Fluorescence Microscopy to produce systematic, high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglion, and P-19 (mouse embryonic carcinoma stem cells) neurons. We measure how the stiffness of neurons changes both during neurite outgrowth and upon disruption of microtubules of the cell. We find reversible local stiffening of the cell during growth, and show that the increase in local elastic modulus is primarily due to the formation of microtubules. We also report that cortical and P-19 neurons have similar elasticity maps, with elastic moduli in the range 0.1-2 kPa, with typical average values of 0.4 kPa (P-19) and 0.2 k...

  17. In-trap fluorescence detection of atoms in a microscopic dipole trap

    CERN Document Server

    Hilliard, A J; Sompet, P; Carpentier, A V; Andersen, M F

    2015-01-01

    We investigate fluorescence detection using a standing wave of blue-detuned light of one or more atoms held in a deep, microscopic dipole trap. The blue-detuned standing wave realizes a Sisyphus laser cooling mechanism so that an atom can scatter many photons while remaining trapped. When imaging more than one atom, the blue detuning limits loss due to inelastic light-assisted collisions. Using this standing wave probe beam, we demonstrate that we can count from one to the order of 100 atoms in the microtrap with sub-poissonian precision.

  18. Atomic force fluorescence microscopy : combining the best of two worlds

    NARCIS (Netherlands)

    Kassies, Roelf

    2005-01-01

    The complementary strengths and weaknesses of AFM and optical microscopy leads to the desire to integrate both techniques into a single microscope. This thesis describes the development of a com-bined AFM / confocal °uorescence microscope. This atomic force °uorescence microscope (AFFM) combines hig

  19. Polymerized LB films imaged with a combined atomic force microscope-fluorescence microscope

    OpenAIRE

    Putman, Constant A.J.; Hansma, Helen G.; Gaub, Hermann E.; Hansma, Paul K.

    1992-01-01

    The first results obtained with a new stand-alone atomic force microscope (AFM) integrated with a standard Zeiss optical fluorescence microscope are presented. The optical microscope allows location and selection of objects to be imaged with the high-resolution AFM. Furthermore, the combined microscope enables a direct comparison between features observed in the fluorescence microscope and those observed in the images obtained with the AFM, in air or under liquid. The cracks in polymerized La...

  20. A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy

    Science.gov (United States)

    Chinni, Rosemarie C.

    2012-01-01

    This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples…

  1. Research of the interaction between kangai injection and human serum albumin by fluorescence spectroscopy

    Science.gov (United States)

    Ye, Changbin; Lin, Xiaogang; Zhu, Hao; Li, Wenchao; Wu, Jie

    2015-10-01

    The interaction between drugs and serum albumin is the theoretical basis of pharmacology research. Kangai injection with invigorating Qi, enhancing the immune function, is widely used for a variety of malignant tumor treatment. Fluorescence spectroscopy was adopted due to its high sensitivity and other advantages. The interaction between kangai injection and human serum albumin (HSA) in physiological buffer (pH 7.4) was investigated by fluorescence spectroscopy and UV-Vis absorption spectroscopy. The results of fluorescence spectrum at three temperature (296K, 303K and 310K) showed the degree of binding at 310K is the highest. Also, the maximum emission peak has a slight blue shift, which indicates that the interaction between kangai injection and HSA has an effect on the conformation of HSA. That is, the microenvironment of tryptophan increase hydrophobic due to the increase of the concentration of kangai injection. Results obtained from analysis of fluorescence spectrum and fluorescence intensity indicated that kangai injection has a strong ability to quench the intrinsic fluorescence of HSA. And according to the Stern-Volume equation, the quenching mechanism is static quenching, which is further proved by the UV-Vis absorption spectroscopy.

  2. Nitrogen atom detection in low-pressure flames by two-photon laser-excited fluorescence

    OpenAIRE

    Bittner, Jürgen; Lawitzki, Annette; Meier, Ulrich; Kohse-Höinghaus, Katharina

    1991-01-01

    Nitrogen atoms have been detected in stoichiometric flat premixed H2/O2/N2 flames at 33 and 96 mbar doped with small amounts of NH3, HCN, and (CN)2 using two-photon laser excitation at 211 nm and fluorescence detection around 870 nm. The shape of the fluorescence intensity profiles versus height above the burner surface is markedly different for the different additives. Using measured quenching rate coefficients and calibrating with the aid of known N-atom concentrations in a discharge flow r...

  3. The stationary resonance fluorescence of a two-level atom in a cat-state field

    Science.gov (United States)

    Tomilin, V. A.; Il'ichov, L. V.

    2016-09-01

    We investigate the resonance fluorescence of a two-level atom placed in non-classical field which is a superposition of Glauber coherent states. The source of this superposition known under the common name of 'Schrödinger cat'-states is explicitly incorporated into the model. This let us to explore the stationary regime. In the strong (multiphoton) field limit the steady-state of the atom+photons system is found. We evaluated the spectrum of the resonance fluorescence. It appears to be one-component in contrast to the case with the classical external field.

  4. Diagnosis of corneal pathology by laser fluorescence spectroscopy

    Science.gov (United States)

    Salmin, V. V.; Lazarenko, V. I.; Salmina, A. B.; Hovalyg, M. Sh.; Vladimirova, E. S.

    2012-09-01

    We have studied the difference between the fluorescence spectra of the human cornea in vivo under normal conditions and after contact lenses have been worn for different lengths of time, with excitation by emission from a nitrogen laser (337 nm). The most significant sections of the difference spectrum were identified, corresponding to peaks for endogenous fluorophores (NADH and collagen). A high correlation was found between how long the contact lenses have been worn and the fluorescence intensity ratio for wavelengths 460 nm and 410 nm.

  5. Spectroscopy and Fluorescence Lifetime Imaging Microscopy To Probe the Interaction of Bovine Serum Albumin with Graphene Oxide.

    Science.gov (United States)

    Kuchlyan, Jagannath; Kundu, Niloy; Banik, Debasis; Roy, Arpita; Sarkar, Nilmoni

    2015-12-29

    The interaction of graphene oxide (GO) with bovine serum albumin (BSA) in aqueous buffer solution has been investigated with various spectroscopic and imaging techniques. At single molecular resolution this interaction has been performed using fluorescence correlation spectroscopy (FCS) and fluorescence lifetime imaging microscopy (FLIM) techniques. The conformational dynamics of BSA on GO's influence have been explored by FCS and circular dichroism (CD) spectroscopy. For the FCS studies BSA was labeled covalently by a fluorophore, Alexa Fluor 488. On the addition of GO in phosphate buffer of 10 mM at pH 7.4 the diffusion time (τD) and the hydrodynamic radius (Rh) of BSA increase due to adsorption of BSA. Conformational relaxation time components of native BSA drastically vary with the addition of GO, signifying the change of conformational dynamics of BSA after addition of GO. The adsorption isotherm also indicates significant adsorption of BSA on the GO surface. Adsorption of BSA on the GO surface has shown in direct images of atomic force microscopy (AFM) and FLIM. Fluorescence quenching study of BSA with addition of GO also indicates that there is strong interaction between BSA and GO. PMID:26646418

  6. Quantitative analysis of essential oils of Thymus daenensis using laser-induced fluorescence and Raman spectroscopy.

    Science.gov (United States)

    Khoshroo, H; Khadem, H; Bahreini, M; Tavassoli, S H; Hadian, J

    2015-11-10

    Laser-induced fluorescence and Raman spectroscopy are used for the investigation of different genotypes of Thymus daenensis native to the Ilam province of Iran. Different genotypes of T. daenensis essential oils, labeled T1 through T7, possess slight differences with regard to the composition of the thymol. The gas chromatography-mass spectrometry (GC-MS) method is performed to determine the concentration of each constituent as a reference method. The Raman spectra of different concentrations of pure thymol dissolved in hexane as standard samples are obtained via a laboratory prototype Raman spectroscopy setup for the calculation of the calibration curve. The regression coefficient and limit of detection are calculated. The possibility of the differentiation of different genotypes of T. daenensis is also examined by laser-induced fluorescence spectroscopy, although we do not know the exact amounts of their components. All the fluorescence spectral information is used jointly by cluster analysis to differentiate between 7 genotypes. Our results demonstrate the acceptable precision of Raman spectroscopy with GC-MS and corroborate the capacity of Raman spectroscopy in applications in the quantitative analysis field. Furthermore, the cluster analysis results show that laser-induced fluorescence spectroscopy is an acceptable technique for the rapid classification of different genotypes of T. daenensis without having any previous information of their exact amount of constituents. So, the ability to rapidly and nondestructively differentiate between genotypes makes it possible to efficiently select high-quality herbs from many samples. PMID:26560783

  7. Variation of fluorescence spectroscopy during the menstrual cycle

    Science.gov (United States)

    Macaulay, Calum; Richards-Kortum, Rebecca; Utzinger, Urs; Fedyk, Amanda; Neely Atkinson, E.; Cox, Dennis; Follen, Michele

    2002-06-01

    Cervical autofluorescence has been demonstrated to have potential for real-time diagnosis. Inter-patient and intra-patient variations in fluorescence intensity have been measured. Inter-patient measurements may vary by a factor of ten, while intra-patient measurements may vary by a factor of two. Age and menopausal status have been demonstrated to account for some of the variations, while race and smoking have not. In order to explore in detail the role of the menstrual cycle in intra-patient variation, a study was designed to measure fluorescence excitation emission matrices (EEMs) in patients daily throughout one cycle. Ten patients with a history of normal menstrual cycles and normal Papanicolaou smears underwent daily measurements of fluorescence EEMs from three colposcopically normal sites throughout one menstrual cycle. Changes in signals from porphyrin, NADH, and FAD fluorescence and blood absorption were noted when the data was viewed in a graphical format. Visually interpreted features of the EEMs in this graphical format did not appear to correlate with the day of the menstrual cycle with the exception that blood absorption features were more prominent during the menstrual phase (during which bleeding occurs), suggesting that measurements during the menstrual phase should be avoided. Variations in cycle date likely do not account for inter- or intra-patient variations.

  8. Fluorescence relaxation spectroscopy: light on dynamical structures of flavoproteins.

    NARCIS (Netherlands)

    Burten-Bastiaens, P.I.H.

    1992-01-01

    Refinements in technique and data analysis have opened new avenues for a detailed interpretation of protein fluorescence. What is more, by combining new insights in protein structure and dynamics with improved knowledge of photophysics of biological chromophores, the coupling between structure-funct

  9. New method for tissue indentification: resonance fluorescence spectroscopy

    Science.gov (United States)

    Neu, Walter

    1991-11-01

    The method proposed in this paper is based on the detection of resonantly enhanced fluorescence emission induced by a tunable dye laser. First test on anorganic samples exposed to air and to saline solution demonstrate the potential of this technique. A XeCl excimer-laser ((lambda) equals308 nm) pulse, guided by quartz fibers, causes an efficient ablation of the irradiated samples. The specific species to be detected in the ablation plume determines the wavelength of the narrow-band dye-laser radiation. Preferably, it is set to a strong transition of the selected ablation product. Taking into account the formation of the plume, the dye-laser pulse is applied with a certain delay in order to excite resonantly the chosen species in the plume. The resulting resonance fluorescence is then guided by optical fibers to an OMA system. Compared to the broad-band excimer-laser-indiced fluorescence during the ablation process, the resonance fluorescence signal shows a distinct and easily detectable sharp peak. The signal-to-background ratio is improved by one order of magnitude. The achieved increase in sensitivity as well as selectivity is for the benefit of a reliable identification of ablated tissue.

  10. Diagnosis of atherosclerotic tissue by resonance fluorescence spectroscopy

    Science.gov (United States)

    Neu, Walter; Haase, Karl K.; Tischler, Christian; Nyga, Ralf; Karsch, Karl R.

    1991-05-01

    Resonantly enhanced fluorescence emission induced by a tunable dye laser can be used for the identification of ablated atherosclerotic tissue. This method has been tested with anorganic samples exposed to air and to saline solution. A XeCl excimer laser pulse ((lambda) = 308 nm), delivered by a fused silica optical fiber, causes an efficient ablation of the irradiated samples. The wavelength of the narrow-band dye laser radiation is set to a strong transition of a specific species to be detected in the ablation plume. Taking into account the formation of the plume, the dye laser pulse is applied with a certain delay in order to excite resonantly the selected species in the plume. The resulting resonance fluorescence then is guided by optical fibers to an optical multi-channel analyzer system. Compared to the broad-band fluorescence during excimer laser ablation the resonance fluorescence signal shows a distinct and easily detectable sharp peak. The signal-to-background ratio is improved by one order of magnitude.

  11. Quantitative Tissue Spectroscopy of Near Infrared Fluorescent Nanosensor Implants.

    Science.gov (United States)

    Iverson, Nicole M; Bisker, Gili; Farias, Edgardo; Ivanov, Vsevolod; Ahn, Jiyoung; Wogan, Gerald N; Strano, Michael S

    2016-05-01

    Implantable, near infrared (nIR) fluorescent nanosensors are advantageous for in vivo monitoring of biological analytes since they can be rendered selective for a particular target molecule while utilizing their unique optical properties and the nIR tissue transparency window for information transfer without an internal power source or telemetry. However, basic questions remain regarding the optimal encapsulation platform, geometrical properties, and concentration ranges required for high signal to noise ratio and effective detection through biological tissue. In this work, we systematically explore these variables quantitatively to optimize the performance of such optical nanosensors for biomedical applications. We investigate both alginate and polyethylene glycol (PEG) as model hydrogel systems, encapsulating d(GT)15 ssDNA-wrapped single-walled carbon nanotubes (SWNT) as model fluorescent nanoparticle sensors, responsive to riboflavin. Hydrogel sensors implanted 0.5 mm into thick tissue samples exhibit 50% reduction of initial fluorescence intensity, allowing an optical detection limit of 5.4 mm and 5.1 mm depth in tissue for alginate and PEG gels, respectively, at a SWNT concentration of 10 mg L(-1), and 785 nm laser excitation of 80 mW and 30 s exposure. These findings are supported with in vivo nIR fluorescent imaging of SWNT hydrogels implanted subcutaneously in mice. For the case of SWNT, we find that the alginate system is preferable in terms of emission intensity, sensor response, rheological properties, and shelf life. PMID:27305824

  12. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    Science.gov (United States)

    Lee, Geon Joon; Sim, Geon Bo; Choi, Eun Ha; Kwon, Young-Wan; Kim, Jun Young; Jang, Siun; Kim, Seong Hwan

    2015-01-01

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  13. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Geon Joon, E-mail: gjlee@kw.ac.kr; Sim, Geon Bo; Choi, Eun Ha [Plasma Bioscience Research Center/Department of Electrical and Biological Physics, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Kwon, Young-Wan [KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Jun Young; Jang, Siun; Kim, Seong Hwan, E-mail: piceae@naver.com [Department of Microbiology and Institute of Basic Sciences, Dankook University, Cheonan 330-714 (Korea, Republic of)

    2015-01-14

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  14. Study of high density polyethylene under UV irradiation or mechanical stress by fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Due to their diversity and their wide range of applications, polymers have emerged in our environment. For technical applications, these materials can be exposed to aggressive environment leading to an alteration of their properties. The effects of this degradation are linked to the concept of life duration, corresponding to the time required for a property to reach a threshold below which the material becomes unusable. Monitoring the ageing of polymer materials constitute a major challenge. Fluorescence spectroscopy is a technique able to provide accurate information concerning this issue. In this study, emphasis was placed on the use of fluorescence spectroscopy to study the phenomena involved in either the UV radiation or mechanical stresses of a polymer. In the case of high density polyethylene, the lack of intrinsic fluorescent signal leads to the use of a dye. This dye gives a fluorescent response depending on its microenvironment. All modifications in the macromolecular chain generate a shift of the fluorescent peak. This work can be dissociated in two major parts, on one hand the influence of UV aging on the fluorescent response and in another hand the influence of mechanical stresses. In the first part, complementary analyses like FTIR or DSC are used to correlate fluorescent results with known photo degradation mechanisms. The results show the great sensibility of the technique to the microstructural rearrangement in the polymer. In the second part, the dependence between the stress and the fluorescence emission gives opportunity to evaluate internal stresses in the material during cyclic solicitations. (author)

  15. Laser spectroscopy of atoms in superfluid helium for the measurement of nuclear spins and electromagnetic moments of radioactive atoms

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, T., E-mail: tomomi.fujita@riken.jp [Osaka University, Department of Physics (Japan); Furukawa, T. [Tokyo Metropolitan University, Department of Physics (Japan); Imamura, K.; Yang, X. F. [RIKEN Nishina Center (Japan); Hatakeyama, A. [Tokyo University of Agriculture and Technology, Department of Applied Physics (Japan); Kobayashi, T. [RIKEN Center for Advanced Photonics (Japan); Ueno, H. [RIKEN Nishina Center (Japan); Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan); Shimoda, T. [Osaka University, Department of Physics (Japan); Matsuo, Y. [Hosei University, Department of Advanced Sciences (Japan); Collaboration: OROCHI Collaboration

    2015-11-15

    A new laser spectroscopic method named “OROCHI (Optical RI-atom Observation in Condensed Helium as Ion catcher)” has been developed for deriving the nuclear spins and electromagnetic moments of low-yield exotic nuclei. In this method, we observe atomic Zeeman and hyperfine structures using laser-radio-frequency/microwave double-resonance spectroscopy. In our previous works, double-resonance spectroscopy was performed successfully with laser-sputtered stable atoms including non-alkali Au atoms as well as alkali Rb and Cs atoms. Following these works, measurements with {sup 84−87}Rb energetic ion beams were carried out in the RIKEN projectile fragment separator (RIPS). In this paper, we report the present status of OROCHI and discuss its feasibility, especially for low-yield nuclei such as unstable Au isotopes.

  16. Atomic Oscillator Strengths by Emission Spectroscopy and Lifetime Measurements

    Science.gov (United States)

    Wiese, W. L.; Griesmann, U.; Kling, R.; Musielok, J.

    2002-11-01

    Over the last seven years, we have carried out numerous oscillator strength measurements for some light and medium heavy elements (Musielok et al. 1995, 1996, 1997, 1999, 2000; Veres & Wiese 1996; Griesmann et al. 1997; Bridges & Wiese 1998; Kling et al. 2001; Kling & Gries- mann 2000; Bridges & Wiese to be published). Most recently we have determined numerous transitions of Mu II (Kling et al. 2001; Kling & Griesmann 2000) and are now working on Cl I (Bridges & Wiese to be published). See the summary statement at the end of the text. For the emission measurements, we have applied either a high-current wall-stabilized arc (described for example, in Musielok et al. (1999)), or a high-current hollow cathode, or a Penning discharge. The latter two sources were used for branching ratio measurements from common upper 1ev- els, while the wall-stabilized arc was operated at atmospheric pressure under the condition of partial local thermodynamic equilibrium, which allows the measurement of relative transition probabilities. Absolute data were obtained by combining the emission results with lifetime data measured by other research groups, especially the University of Hannover, with which we have closely collaborated. This group uses the laser induced fluorescence (LIF) technique. Our emission spectra were recorded for the light elements with a 2 m grating spectrometer, or, for Mu II, with an FT 700 vacuum ultraviolet Fourier transform spectrometer. The radiometric calibration was carried out with a tungsten strip lamp for the visible part of the spectrum and with a deuterium lamp for the ultraviolet. All measurements were made under optically thin conditions, which was checked by doubling the path length with a focusing mirror setup. Typical uncertainties of the measured oscillator strengths are estimated to be in the range 15%-20% (one-standard deviation). However, discrepancies with advanced atomic structure theories are sometimes much larger. In Tables 1-3 and Fig. 1, we

  17. Absorption spectroscopy characterization measurements of a laser-produced Na atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Ching, C.H.; Bailey, J.E.; Lake, P.W.; Filuk, A.B.; Adams, R.G.; McKenney, J.

    1996-06-01

    This work describes a pulsed Na atomic beam source developed for spectroscopic diagnosis of a high-power ion diode on the Particle Beam Fusion Accelerator II. The goal is to produce a {approximately} 10{sup 12}-cm{sup {minus}3}-density Na atomic beam that can be injected into the diode acceleration gap to measure electric and magnetic fields from the Stark and Zeeman effects through laser-induced-fluorescence or absorption spectroscopy. A {approximately} 10 ns fwhm, 1.06 {micro}m, 0.6 J/cm{sup 2} laser incident through a glass slide heats a Na-bearing thin film, creating a plasma that generates a sodium vapor plume. A {approximately} 1 {micro}sec fwhm dye laser beam tuned to 5,890 {angstrom} is used for absorption measurement of the Na I resonant doublet by viewing parallel to the film surface. The dye laser light is coupled through a fiber to a spectrograph with a time-integrated CCD camera. A two-dimensional mapping of the Na vapor density is obtained through absorption measurements at different spatial locations. Time-of-flight and Doppler broadening of the absorption with {approximately} 0.1 {angstrom} spectral resolution indicate that the Na neutral vapor temperature is about 0.5 to 2 eV. Laser-induced-fluorescence from {approximately} 1 {times} 10{sup 12}-cm{sup {minus}3} Na I 3s-3p lines observed with a streaked spectrograph provides a signal level sufficient for {approximately} 0.06 {angstrom} wavelength shift measurements in a mock-up of an ion diode experiment.

  18. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    International Nuclear Information System (INIS)

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg−1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (∼0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13− coordination environment (e.g. >90%) and no (III XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 μm×300 μm beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO2 matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: • Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. • The americium redox state as determined from XAS data of irradiated fuel material was Am(III). • In the sample, the Am3+ face an AmO813− coordination environment in the (Pu,U)O2 matrix. • The americium dioxide is reduced by the uranium dioxide matrix

  19. Anatomy-Based Algorithms for Detecting Oral Cancer Using Reflectance and Fluorescence Spectroscopy

    OpenAIRE

    McGee, Sasha; Mardirossian, Vartan; Elackattu, Alphi; Mirkovic, Jelena; Pistey, Robert; Gallagher, George; Kabani, Sadru; Yu, Chung-Chieh; Wang, Zimmern; Badizadegan, Kamran; Grillone, Gregory; Feld, Michael S.

    2009-01-01

    OBJECTIVES: We used reflectance and fluorescence spectroscopy to noninvasively and quantitatively distinguish benign from dysplastic/malignant oral lesions. We designed diagnostic algorithms to account for differences in the spectral properties among anatomic sites (gingiva, buccal mucosa, etc). METHODS: In vivo reflectance and fluorescence spectra were collected from 71 patients with oral lesions. The tissue was then biopsied and the specimen evaluated by histopathology. Quantitative par...

  20. Detection of plant oil addition to cheese by synchronous fluorescence spectroscopy

    OpenAIRE

    Dankowska, Anna; Małecka, Maria; Kowalewski, Wojciech

    2015-01-01

    The fraudulent addition of plant oils during the manufacturing of hard cheeses is a real issue for the dairy industry. Considering the importance of monitoring adulterations of genuine cheeses, the potential of fluorescence spectroscopy for the detection of cheese adulteration with plant oils was investigated. Synchronous fluorescence spectra were collected within the range of 240 to 700 nm with different wavelength intervals. The lowest detection limits of adulteration, 3.0 and 4.4%, respect...

  1. Spatially and Temporally Resolved Atomic Oxygen Measurements in Short Pulse Discharges by Two Photon Laser Induced Fluorescence

    Science.gov (United States)

    Lempert, Walter; Uddi, Mruthunjaya; Mintusov, Eugene; Jiang, Naibo; Adamovich, Igor

    2007-10-01

    Two Photon Laser Induced Fluorescence (TALIF) is used to measure time-dependent absolute oxygen atom concentrations in O2/He, O2/N2, and CH4/air plasmas produced with a 20 nanosecond duration, 20 kV pulsed discharge at 10 Hz repetition rate. Xenon calibrated spectra show that a single discharge pulse creates initial oxygen dissociation fraction of ˜0.0005 for air like mixtures at 40-60 torr total pressure. Peak O atom concentration is a factor of approximately two lower in fuel lean (φ=0.5) methane/air mixtures. In helium buffer, the initially formed atomic oxygen decays monotonically, with decay time consistent with formation of ozone. In all nitrogen containing mixtures, atomic oxygen concentrations are found to initially increase, for time scales on the order of 10-100 microseconds, due presumably to additional O2 dissociation caused by collisions with electronically excited nitrogen. Further evidence of the role of metastable N2 is demonstrated from time-dependent N2 2^nd Positive and NO Gamma band emission spectroscopy. Comparisons with modeling predictions show qualitative, but not quantitative, agreement with the experimental data.

  2. Changes and characteristics of dissolved organic matter in a constructed wetland system using fluorescence spectroscopy.

    Science.gov (United States)

    Yao, Yuan; Li, Yun-Zhen; Guo, Xu-Jing; Huang, Tao; Gao, Ping-Ping; Zhang, Ying-Pei; Yuan, Feng

    2016-06-01

    Domestic wastewater was treated by five constructed wetland beds in series. Dissolved organic matter (DOM) collected from influent and effluent samples from the constructed wetland was investigated using fluorescence spectroscopy combined with fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and two-dimensional correlation spectroscopy (2D-COS). This study evaluates the capability of these methods in detecting the spectral characteristics of fluorescent DOM fractions and their changes in constructed wetlands. Fluorescence excitation-emission matrix (EEM) combined with FRI analysis showed that protein-like materials displayed a higher removal ratio compared to humic-like substances. The PARAFAC analysis of wastewater DOM indicated that six fluorescent components, i.e., two protein-like substances (C1 and C6), three humic-like substances (C2, C3 and C5), and one non-humic component (C4), could be identified. Tryptophan-like C1 was the dominant component in the influent DOM. The removal ratios of six fluorescent components (C1-C6) were 56.21, 32.05, 49.19, 39.90, 29.60, and 45.87 %, respectively, after the constructed wetland treatment. Furthermore, 2D-COS demonstrated that the sequencing of spectral changes for fluorescent DOM followed the order 298 nm → 403 nm → 283 nm (310-360 nm) in the constructed wetland, suggesting that the peak at 298 nm is associated with preferential tryptophan fluorescence removal. Variation of the fluorescence index (FI) and the ratio of fluorescence components indicated that the constructed wetland treatment resulted in the decrease of fluorescent organic pollutant with increasing the humification and chemical stability of the DOM. PMID:26976008

  3. One-atom detection using resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    A new measuring technique which can detect a single atom of a given kind, even in the presence of 1019 or more atoms of another kind, with good space and time resolution, was utilized to study the density fluctuation of less than 100 cesium atoms in a small volume of space filled with inert gases. Repeated measurements of the absolute number of atoms in a defined volume at an arbitrary time were recorded for the first time in order to obtain a statistical distribution giving the fluctuation of the number of atoms around the mean value. Numerous other physics applications of the one-atom detector are briefly described

  4. Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media

    Science.gov (United States)

    Cerussi, Albert Edward

    1999-09-01

    In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of

  5. Observation of DNA Molecules Using Fluorescence Microscopy and Atomic Force Microscopy

    Science.gov (United States)

    Ito, Takashi

    2008-01-01

    This article describes experiments for an undergraduate instrumental analysis laboratory that aim to observe individual double-stranded DNA (dsDNA) molecules using fluorescence microscopy and atomic force microscopy (AFM). dsDNA molecules are observed under several different conditions to discuss their chemical and physical properties. In…

  6. Polymerized LB films imaged with a combined atomic force microscope-fluorescence microscope

    NARCIS (Netherlands)

    Putman, Constant A.J.; Hansma, Helen G.; Gaub, Hermann E.; Hansma, Paul K.

    1992-01-01

    The first results obtained with a new stand-alone atomic force microscope (AFM) integrated with a standard Zeiss optical fluorescence microscope are presented. The optical microscope allows location and selection of objects to be imaged with the high-resolution AFM. Furthermore, the combined microsc

  7. Spatial Resolution of Combined Wavelength Modulation Spectroscopy with Integrated Cavity Output Spectroscopy for Atomic Oxygen Detection

    Science.gov (United States)

    Matsui, Makoto; Nakajima, Daisuke

    2015-09-01

    For developments of thermal protection system, atomic oxygen plays important role. However, its measurement method has not been established because the pressure in front of TPS test materials is as high as a few kPa. Our group proposed combined wavelength modulation and integrated output spectroscopies based on the forbidden transition at OI 636 nm to measure the ground-state number densities. In this study, WM-ICOS system is developed and applied to a microwave oxygen plasma to evaluate measurable region. As a result, the estimated number density by ICOS could be measured as low as 1021 m21. For the condition, WM-ICOS was applied. The signal to noise ratio of the 2f signal was 40.4. Then, the sensitivity was improved about 26. This result corresponding to the measurement limit of the partial atomic oxygen pressure of 250 Pa. The sensitivity of WM-ICOS was found to enough to diagnose the shock layer in high enthalpy flows. However, the spatial resolution was as large as 8 mm. The size of the beam pattern depends on the cavity length, robust ness of the cavity and accuracy of the cavity alignment. In this presentation, the relationship among these parameters will be discussed.

  8. Symposium on atomic spectroscopy (SAS-83): abstracts and program

    Energy Technology Data Exchange (ETDEWEB)

    1983-09-01

    Abstracts of papers given at the symposium are presented. Session topics include: Rydbergs, optical radiators, and planetary atoms; highly ionized atoms; ultraviolet radiation; theory, ion traps, and laser cooling; beam foil; and astronomy. (GHT)

  9. Symposium on atomic spectroscopy (SAS-83): abstracts and program

    International Nuclear Information System (INIS)

    Abstracts of papers given at the symposium are presented. Session topics include: Rydbergs, optical radiators, and planetary atoms; highly ionized atoms; ultraviolet radiation; theory, ion traps, and laser cooling; beam foil; and astronomy

  10. Investigation of the Interaction between Adenosine and Human Serum Albumin by Fluorescent Spectroscopy and Molecular Modeling

    Institute of Scientific and Technical Information of China (English)

    CUI Feng-Ling; WANG Jun-Li; LI Fang; FAN Jing; QU Gui-Rong; YAO Xiao-Jun; LEI Bei-Lei

    2008-01-01

    The binding interaction of adenosine with human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectroscopy in combination with a molecular modeling method. A strong fluorescence quenching reaction of adenosine to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to relevant fluorescent data and Vant'Hoff equation. The hydrophobic interaction was a predominant intermolecular force in order to stabilize the complex, which was in agreement with the results of molecular modeling study.

  11. Using the laser-induced fluorescence spectroscopy in the differentiation between normal and neoplastichuman breast tissue.

    Science.gov (United States)

    Hage, R; Galhanone, P R; Zângaro, R A; Rodrigues, K C; Pacheco, M T T; Martin, A A; Netto, M M; Soares, F A; da Cunha, I W

    2003-01-01

    This article reports results of the in vitro study for potential evaluation of the laser-induced fluorescence spectroscopy in the differentiation between normal and neoplastic human breast tissue. A coumarine dye laser pumped by nitrogen laser generated an excitation light centered at 458 nm. In order to collect the fluorescence signal was used an optical fiber catheter coupled to a spectrometer and CCD detector. Fluorescence spectra were recorded from normal and neoplastic (benign and malignant) human breast tissue, adding up 94 different areas. The discrimination between normal and neoplasm groups reach a sensitivity and specificity of 100%. PMID:14505202

  12. Determination of changes in wastewater quality through a treatment works using fluorescence spectroscopy.

    Science.gov (United States)

    Bridgeman, John; Baker, Andy; Carliell-Marquet, Cynthia; Carstea, Elfrida

    2013-01-01

    Fluorescence spectroscopy was used to characterize municipal wastewater at various stages of treatment in order to understand how its fluorescence signature changes with treatment and how the signal relates to biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The impact of size fractionation on the fluorescence signal was also investigated. Fluorescence measurements were taken for unfiltered and filtered (0.45 and 0.20 microm) samples of crude, settled and secondary treated wastewater (activated sludge and trickling filter), and final effluent. Good correlations were observed for unfiltered, diluted wastewater samples between BOD and fluorescence intensity at excitation 280 nm, emission 350 nm (Peak T1) (r = 0.92) and between COD and Peak T1 intensity (r = 0.85). The majority of the T1 and T2 signal was found to be derived from the wastewater quality assessment and process control of wastewater treatment works. PMID:24617065

  13. In vivo study of the human skin by the method of laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The goals of this study are to perform a preliminary evaluation of the diagnostic potential of noninvasive laser-induced auto-fluorescence spectroscopy (LIAFS) for human skin and optimize of detection and diagnosis of hollow organs and skin. In recent years, there has been growing interest in the use of laser-induced fluorescence to discriminate disease from normal surrounding tissue. The most fluorescence studies have used exogenous fluorophores of this discrimination. The laser-induced auto-fluorescence which is used for diagnosis of tissues in the human body avoids administration of any drugs. In this study a technique for optical biopsy of in vivo human skin is presented. The auto-fluorescence characterization of tissue relies on different spectral properties of tissues. It was demonstrated a differentiation between normal skin and skin with vitiligo. Two main endogenous fluorophores in the human skin account for most of the cellular auto-fluorescence for excitation wavelength 337 nm reduced from of nicotinamide adenine dinucleotide and collagen. The auto-fluorescence spectrum of human skin depend on main internal absorbers which are blood and melanin. In this study was described the effect caused by blood and melanin content on the shape of the auto-fluorescence spectrum of human skin. Human skin fluorescence spectrum might provide dermatologists with important information and such investigations are successfully used now in skin disease diagnostics, in investigation of the environmental factor impact or for evaluation of treatment efficiency. (authors)

  14. Far-field resonance fluorescence from a dipole-interacting laser-driven cold atomic gas

    CERN Document Server

    Jones, Ryan; Olmos, Beatriz

    2016-01-01

    We analyze the temporal response of the fluorescence light that is emitted from a dense gas of cold atoms driven by a laser. When the average interatomic distance is smaller than the wavelength of the photons scattered by the atoms, the system exhibits strong dipolar interactions and collective dissipation. We solve the exact dynamics of small systems with different geometries and show how these collective features are manifest in the scattered light properties such as the photon emission rate, the power spectrum and the second-order correlation function. By calculating these quantities beyond the weak driving limit, we make progress in understanding the signatures of collective behavior in these many-body systems. Furthermore, we clarify the role of disorder on the resonance fluorescence, of direct relevance for recent experimental efforts that aim at the exploration of many-body effects in dipole-dipole interacting gases of atoms.

  15. Laser induced fluorescence spectroscopy of the Ca dimer deposited on helium and mixed helium/xenon clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gaveau, Marc-André; Pothier, Christophe; Briant, Marc; Mestdagh, Jean-Michel [Laboratoire Francis Perrin, CNRS URA 2453, DSM/IRAMIS/LIDYL, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France)

    2014-12-09

    We study how the laser induced fluorescence spectroscopy of the calcium dimer deposited on pure helium clusters is modified by the addition of xenon atoms. In the wavelength range between 365 and 385 nm, the Ca dimer is excited from its ground state up to two excited electronic states leading to its photodissociation in Ca({sup 1}P)+Ca({sup 1}S): this process is monitored by recording the Ca({sup 1}P) fluorescence at 422.7nm. One of these electronic states of Ca{sub 2} is a diexcited one correlating to the Ca(4s4p{sup 3}P(+Ca(4s3d{sup 3}D), the other one is a repulsive state correlating to the Ca(4s4p1P)+Ca(4s21S) asymptote, accounting for the dissociation of Ca{sub 2} and the observation of the subsequent Ca({sup 1}P) emission. On pure helium clusters, the fluorescence exhibits the calcium atomic resonance line Ca({sup 1}S←{sup 1}P) at 422.7 nm (23652 cm{sup −1}) assigned to ejected calcium, and a narrow red sided band corresponding to calcium that remains solvated on the helium cluster. When adding xenon atoms to the helium clusters, the intensity of these two features decreases and a new spectral band appears on the red side of calcium resonance line; the intensity and the red shift of this component increase along with the xenon quantity deposited on the helium cluster: it is assigned to the emission of Ca({sup 1}P) associated with the small xenon aggregate embedded inside the helium cluster.

  16. Electric field strength measurements in a megavolt vacuum diode using laser induced fluorescence of an atomic beam

    International Nuclear Information System (INIS)

    A combined technique of an atomic beam probing and laser-induced fluorescence spectroscopy (LIFABS) is applied for measuring of local electric field in a 1 MV, 100 kJ, 4 μsec electron diode. Laser-produced lithium beam is stepwise excited by two resonant wide-band laser beams. Stark-splitted spontaneous emission from n=4 level is detected with a polychromator. Time dependence of the electric field was inferred from splitting of the 460.3 nm lithium line. The electric field strength F grows during a pulse from 160 to 260 kV/cm in the center of a 6 cm gap. By comparing calculated and experimental F-values, expansion of the emission boundaries of the cathode and anode plasmas was reconstructed

  17. 2-Dimensional Fluorescence Spectroscopy: Determining the Temperature-Dependent Conformations of Porphyrin Dimers and Nucleic Acids

    Science.gov (United States)

    Widom, Julia; Perdomo-Ortiz, Alejandro; Aspuru-Guzik, Alan; Marcus, Andrew

    2012-02-01

    I will describe spectroscopic studies on a covalently-linked zinc tetraphenylporphyrin dimer embedded in a phospholipid bilayer membrane. Using phase-modulation 2-Dimensional Fluorescence Spectroscopy (2D FS, a fluorescence-detected version of 2D electronic spectroscopy) along with linear absorption and fluorescence spectroscopy, it was found that the dimer adopts two predominant conformations in the membrane, and that the relative populations of these two states change as a function of temperature. Simultaneously fitting the linear absorption spectrum and the 2D FS spectra at four different excitation wavelengths revealed a wealth of information about these two states, including their relative populations, relative fluorescence quantum yields, the strength of the exciton coupling present in each state, and the approximate angles between the electronic transition dipole moments of the two porphyrins. Ongoing analysis focuses on elucidating the relaxation and energy transfer dynamics of this system through the population time dependence of the 2D spectra. Finally, I will present preliminary results from experiments in which 2D FS was performed with ultraviolet excitation to study the conformations of DNA constructs labeled with a fluorescent analogue of guanine.

  18. Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

    International Nuclear Information System (INIS)

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

  19. Characterization of Anabaena cylindrica Solution System Using Synchronous- Scan Fluorescence Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-li; DENG Nan-sheng; TAO Shu

    2005-01-01

    The characterization of the algae Anabaena cylindrica solu tion with Fe (Ⅲ) was investigated using fluorescence emission and syn chronous-scan spectroscopy. The ranges of concentrations of algae and Fe (Ⅲ) in aqueous solutions were 5. 0 × 107-2. 5 × 108 cell/L and 10-60μmol/L, respectively. The effective characterization method used was synchronous-scan fluorescence spectroscopy (SFS). The wavelength difference (△λ) of 90 nm was maintained between excitation wavelength (λex) and emission wavelength(λem ). The peak was observed at about λex 236 nm/λem 326 nm for synchronous-scan fluorescence spectroscopy. The fluorescence quenching in system of algae-Fe( Ⅲ)-HA was studied using synchronous-scan spectroscopy for the first time. Fe(Ⅲ) was clearly the effective quencher. The relationship between I0 / I (quenching efficiency)and c (concentration of Fe (Ⅲ) added) was a linear correlation for the al gae solution with Fe(Ⅲ). Also, Aldrich humic acid (HA) was found to be an effective quencher.

  20. Combination of Micro-fluidic Chip with Fluorescence Correlation Spectroscopy for Single Molecule Detection

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A single molecule detection technique was developed by the combination of a single channel poly (dimethylsiloxane)/glass micro-fluidic chip and fluorescence correlation spectroscopy (FCS). This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.

  1. Fluorescence kinetics of Trp-Trp dipeptide and its derivatives in water via ultrafast fluorescence spectroscopy.

    Science.gov (United States)

    Jia, Menghui; Yi, Hua; Chang, Mengfang; Cao, Xiaodan; Li, Lei; Zhou, Zhongneng; Pan, Haifeng; Chen, Yan; Zhang, Sanjun; Xu, Jianhua

    2015-08-01

    Ultrafast fluorescence dynamics of Tryptophan-Tryptophan (Trp-Trp/Trp2) dipeptide and its derivatives in water have been investigated using a picosecond resolved time correlated single photon counting (TCSPC) apparatus together with a femtosecond resolved upconversion spectrophotofluorometer. The fluorescence decay profiles at multiple wavelengths were fitted by a global analysis technique. Nanosecond fluorescence kinetics of Trp2, N-tert-butyl carbonyl oxygen-N'-aldehyde group-l-tryptophan-l-tryptophan (NBTrp2), l-tryptophan-l-tryptophan methyl ester (Trp2Me), and N-acetyl-l-tryptophan-l-tryptophan methyl ester (NATrp2Me) exhibit multi-exponential decays with the average lifetimes of 1.99, 3.04, 0.72 and 1.22ns, respectively. Due to the intramolecular interaction between two Trp residues, the "water relaxation" lifetime was observed around 4ps, and it is noticed that Trp2 and its derivatives also exhibit a new decay with a lifetime of ∼100ps, while single-Trp fluorescence decay in dipeptides/proteins shows 20-30ps. The intramolecular interaction lifetime constants of Trp2, NBTrp2, Trp2Me and NATrp2Me were then calculated to be 3.64, 0.93, 11.52 and 2.40ns, respectively. Candidate mechanisms (including heterogeneity, solvent relaxation, quasi static self-quenching or ET/PT quenching) have been discussed.

  2. Laboratory micro-X-ray fluorescence spectroscopy instrumentation and applications

    CERN Document Server

    Haschke, Michael

    2014-01-01

    Micro-X-ray fluorescence offers the possibility for a position- sensitive and non-destructive analysis that can be used for the analysis of non-homogeneous materials and layer systems. This analytical technique has shown a dynamic development in the last 15 years and is used for the analysis of small particles, inclusions, of elemental distributions for a wide range of different applications both in research and quality control. The first experiments were performed on synchrotrons but there is a requirement for laboratory instruments which offers a fast and immediate access for analytical results. The book discuss the main components of a µ-XRF instrument and the different measurement modes, it gives an overview about the various instruments types, considers the special requirements for quantification of non-homogeneous materials and presents a wide range of application for single point and multi-point analysis as well as for distribution analysis in one, two and three dimensions.

  3. Detection of single atoms by resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the RIS technique, a laser is tuned to a wavelength which will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or nonresonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms; and since detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples are given of one-atom detection, including that of the noble gases, in order to show complementarity with AMS methods. For instance, the detection of 81Kr using RIS has interesting applications for solar neutrino research, ice-cap dating, and groundwater dating. 39 refs., 7 figs., 2 tabs

  4. Nonlinear Theory of Anomalous Diffusion and Application to Fluorescence Correlation Spectroscopy

    Science.gov (United States)

    Boon, Jean Pierre; Lutsko, James F.

    2015-12-01

    The nonlinear theory of anomalous diffusion is based on particle interactions giving an explicit microscopic description of diffusive processes leading to sub-, normal, or super-diffusion as a result of competitive effects between attractive and repulsive interactions. We present the explicit analytical solution to the nonlinear diffusion equation which we then use to compute the correlation function which is experimentally measured by correlation spectroscopy. The theoretical results are applicable in particular to the analysis of fluorescence correlation spectroscopy of marked molecules in biological systems. More specifically we consider the cases of fluorescently labeled lipids in the plasma membrane and of fluorescent apoferritin (a spherically shaped oligomer) in a crowded dextran solution and we find that the nonlinear correlation spectra reproduce very well the experimental data indicating sub-diffusive molecular motion.

  5. Resonance ionization spectroscopy: counting noble-gas atoms

    International Nuclear Information System (INIS)

    New work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions) is reported. When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. It is shown that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective

  6. Characterising organic matter in recirculating aquaculture systems with fluorescence EEM spectroscopy.

    Science.gov (United States)

    Hambly, A C; Arvin, E; Pedersen, L-F; Pedersen, P B; Seredyńska-Sobecka, B; Stedmon, C A

    2015-10-15

    The potential of recirculating aquaculture systems (RAS) in the aquaculture industry is increasingly being acknowledged. Along with intensified application, the need to better characterise and understand the accumulated dissolved organic matter (DOM) within these systems increases. Mature RASs, stocked with rainbow trout and operated at steady state at four feed loadings, were analysed by dissolved organic carbon (DOC) analysis and fluorescence excitation-emission matrix (EEM) spectroscopy. The fluorescence dataset was then decomposed by PARAFAC analysis using the drEEM toolbox. This revealed that the fluorescence character of the RAS water could be represented by five components, of which four have previously been identified in fresh water, coastal marine water, wetlands and drinking water. The fluorescence components as well as the DOC showed positive correlations with feed loading, however there was considerable variation between the five fluorescence components with respect to the degree of accumulation with feed loading. The five components were found to originate from three sources: the feed; the influent tap water (groundwater); and processes related to the fish and the water treatment system. This paper details the first application of fluorescence EEM spectroscopy to assess DOM in RAS, and highlights the potential applications of this technique within future RAS management strategies. PMID:26141427

  7. Atomic scale imaging and spectroscopy of individual electron trap states using force detected dynamic tunnelling

    International Nuclear Information System (INIS)

    We report the first atomic scale imaging and spectroscopic measurements of electron trap states in completely non-conducting surfaces by dynamic tunnelling force microscopy/spectroscopy. Single electrons are dynamically shuttled to/from individual states in thick films of hafnium silicate and silicon dioxide. The new method opens up surfaces that are inaccessible to the scanning tunnelling microscope for imaging and spectroscopy on an atomic scale.

  8. New insights into heat induced structural changes of pectin methylesterase on fluorescence spectroscopy and molecular modeling basis

    Science.gov (United States)

    Nistor, Oana Viorela; Stănciuc, Nicoleta; Aprodu, Iuliana; Botez, Elisabeta

    2014-07-01

    Heat-induced structural changes of Aspergillus oryzae pectin methylesterase (PME) were studied by means of fluorescence spectroscopy and molecular modeling, whereas the functional enzyme stability was monitored by inactivation studies. The fluorescence spectroscopy experiments were performed at two pH value (4.5 and 7.0). At both pH values, the phase diagrams were linear, indicating the presence of two molecular species induced by thermal treatment. A red shift of 7 nm was observed at neutral pH by increasing temperature up to 60 °C, followed by a blue shift of 4 nm at 70 °C, suggesting significant conformational rearrangements. The quenching experiments using acrylamide and iodide demonstrate a more flexible conformation of enzyme with increasing temperature, especially at neutral pH. The experimental results were complemented with atomic level observations on PME model behavior after performing molecular dynamics simulations at different temperatures. The inactivation kinetics of PME in buffer solutions was fitted using a first-order kinetics model, resulting in activation energy of 241.4 ± 7.51 kJ mol-1.

  9. A Pragmatic Smoothing Method for Improving the Quality of the Results in Atomic Spectroscopy

    CERN Document Server

    Bennun, Leonardo

    2016-01-01

    A new smoothing method for the improvement on the identification and quantification of spectral functions based on the previous knowledge of the signals that are expected to be quantified, is presented. These signals are used as weighted coefficients in the smoothing algorithm. This smoothing method was conceived to be applied in atomic and nuclear spectroscopies preferably to these techniques where net counts are proportional to acquisition time, such as particle induced X-ray emission (PIXE) and other X-ray fluorescence spectroscopic methods, etc. This algorithm, when properly applied, does not distort the form nor the intensity of the signal, so it is well suited for all kind of spectroscopic techniques. This method is extremely effective at reducing high-frequency noise in the signal much more efficient than a single rectangular smooth of the same width. As all of smoothing techniques, the proposed method improves the precision of the results, but in this case we found also a systematic improvement on the...

  10. Isotopically selective counting of noble gas atoms, using resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    The technique of Resonance Ionization Spectroscopy (RIS) is being extended to develop a means for counting individual atoms of a selected isotope of a noble gas. In this method, lasers are used for RIS to obtain atomic species (Z) selectivity and a small quadrupole mass spectrometer provides isotopic (A) selectivity. A progress report on the objective of counting each atom of a particular isotope of a noble gas is given. (author)

  11. Isotopically selective counting of noble gas atoms, using resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    The technique of Resonance Ionization Spectroscopy (RIS) is being extended to develop a means for counting individual atoms of a selected isotope of a noble gas. In this method, lasers are used for RIS to obtain atomic species (Z) selectivity and a small quadrupole mass spectrometer provides isotopic (A) selectivity. A progress report on the objective of counting each atom of a particular isotope of a noble gas is given. 10 references, 4 figures

  12. Atomic structure of machined semiconducting chips: An x-ray absorption spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Paesler, M.; Sayers, D.

    1988-12-01

    X-ray absorption spectroscopy (XAS) has been used to examine the atomic structure of chips of germanium that were produced by single point diamond machining. It is demonstrated that although the local (nearest neighbor) atomic structure is experimentally quite similar to that of single crystal specimens information from more distant atoms indicates the presence of considerable stress. An outline of the technique is given and the strength of XAS in studying the machining process is demonstrated.

  13. Fluorescence lifetime spectroscopy in multiple-scattering environments: an application to biotechnology

    Science.gov (United States)

    Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio

    1999-07-01

    Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.

  14. In-vivo optical detection of cancer using chlorin e6 – polyvinylpyrrolidone induced fluorescence imaging and spectroscopy

    International Nuclear Information System (INIS)

    Photosensitizer based fluorescence imaging and spectroscopy is fast becoming a promising approach for cancer detection. The purpose of this study was to examine the use of the photosensitizer chlorin e6 (Ce6) formulated in polyvinylpyrrolidone (PVP) as a potential exogenous fluorophore for fluorescence imaging and spectroscopic detection of human cancer tissue xenografted in preclinical models as well as in a patient. Fluorescence imaging was performed on MGH human bladder tumor xenografted on both the chick chorioallantoic membrane (CAM) and the murine model using a fluorescence endoscopy imaging system. In addition, fiber optic based fluorescence spectroscopy was performed on tumors and various normal organs in the same mice to validate the macroscopic images. In one patient, fluorescence imaging was performed on angiosarcoma lesions and normal skin in conjunction with fluorescence spectroscopy to validate Ce6-PVP induced fluorescence visual assessment of the lesions. Margins of tumor xenografts in the CAM model were clearly outlined under fluorescence imaging. Ce6-PVP-induced fluorescence imaging yielded a specificity of 83% on the CAM model. In mice, fluorescence intensity of Ce6-PVP was higher in bladder tumor compared to adjacent muscle and normal bladder. Clinical results confirmed that fluorescence imaging clearly captured the fluorescence of Ce6-PVP in angiosarcoma lesions and good correlation was found between fluorescence imaging and spectral measurement in the patient. Combination of Ce6-PVP induced fluorescence imaging and spectroscopy could allow for optical detection and discrimination between cancer and the surrounding normal tissues. Ce6-PVP seems to be a promising fluorophore for fluorescence diagnosis of cancer

  15. Updated Atomic Data and Calculations for X-ray Spectroscopy

    CERN Document Server

    Foster, A R; Smith, R K; Brickhouse, N S

    2012-01-01

    We describe the latest release of AtomDB, version 2.0.2, a database of atomic data and a plasma modeling code with a focus on X-ray astronomy. This release includes several major updates to the fundamental atomic structure and process data held within AtomDB, incorporating new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions, including the iron L-shell ions from Fe$^{+16}$ to Fe$^{+23}$ and all of the hydrogen- and helium-like sequences. We also describe some of the effects that these changes have on calculated emission and diagnostic line ratios, such as changes in the temperature implied by the He-like G-ratios of up to a factor of 2.

  16. Precise atomic radiative lifetime via photoassociative spectroscopy of ultracold lithium

    International Nuclear Information System (INIS)

    We have obtained spectra of the high-lying vibrational levels of the 13Σ+g state of 6Li2 via photoassociation of ultracold 6Li atoms confined in a magneto-optical trap. The 13Σ+g state of the diatomic molecule correlates to a 2S1/2 state atom plus a 2P1/2 state atom. The long-range part of the molecular interaction potential for this state depends on the 2P atomic radiative lifetime. By calculating the energy eigenvalues of a model potential for the 13Σ+g state and fitting them to the experimentally measured vibrational levels, we have extracted a value for the 2P lifetime of 26.99±0.16 ns. The precision is currently limited by the accuracy of a region of the model potential provided by ab initio calculations

  17. Noise spectroscopy with large clouds of cold atoms

    CERN Document Server

    Kashanian, Samir Vartabi; Guerin, William; Lintz, Michel; Fouché, Mathilde; Kaiser, Robin

    2016-01-01

    Noise measurement is a powerful tool to investigate many phenomena from laser characterization to quantum behavior of light. In this paper, we report on intensity noise measurements obtained when a laser beam is transmitted through a large cloud of cold atoms. While this measurement could possibly investigate complex processes such as the influence of atomic motion, one is first limited by the conversion of the intrinsic laser frequency noise to intensity noise via the atomic resonance. We show that a simple model, based on a mean-field approach, which corresponds to describing the atomic cloud by a dielectric susceptibility, is sufficient to understand the main features of this conversion observed in the experimental intensity noise spectrum.

  18. Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles using Optical Nanofibers: A Review

    CERN Document Server

    Morrissey, Michael J; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

    2013-01-01

    The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining ground in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization and optical trapping schemes. Next, a natural extension on this work to molecules will be introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for particular applications.

  19. Ultrathin atomic vapor film transmission spectroscopy: analysis of Dicke narrowing structure

    Institute of Scientific and Technical Information of China (English)

    Yuanyuan Li; Yanpeng Zhang; Chenli Gan

    2005-01-01

    Transmission sub-Doppler spectroscopy with confined atomic vapor film between two dielectric walls is theoretically studied. Because of atoms flying from wall to wall, where they get de-excited, the atomfield interaction time is anisotropic so that the contribution of slow atoms is enhanced, a sub-Doppler transmission spectroscopy (Dicke narrowing effect) can be obtained when the thickness of the film is much small or comparable with the wavelength even at small angle oblique incidence. It is feasible to get a sub-Doppler structure in a new region (L <λ/4) in experiments.

  20. Modulation Transfer Spectroscopy of Ytterbium Atoms in a Hollow Cathode Lamp

    International Nuclear Information System (INIS)

    We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp. The dependences of its linewidth, slope and magnitude on the various experimental parameters are measured and fitted by the well-known theoretical expressions. The experimental results are in good agreement with the theoretical prediction. We have observed the Dicke narrowing effect by increasing the current of the hollow cathode lamp. It is also found that there are the optimal current and laser power to generate the better modulation transfer spectroscopy signal, which can be employed for locking the laser frequency to the atomic transition. (atomic and molecular physics)

  1. Assessing the photoaging process at sun exposed and non-exposed skin using fluorescence lifetime spectroscopy

    Science.gov (United States)

    Saito Nogueira, Marcelo; Kurachi, Cristina

    2016-03-01

    Photoaging is the skin premature aging due to exposure to ultraviolet light, which damage the collagen, elastin and can induce alterations on the skin cells DNA, and, then, it may evolve to precancerous lesions, which are widely investigated by fluorescence spectroscopy and lifetime. The fluorescence spectra and fluorescence lifetime analysis has been presented as a technique of great potential for biological tissue characterization at optical diagnostics. The main targeted fluorophores are NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), which have free and bound states, each one with different average lifetimes. The average lifetimes for free and bound NADH and FAD change according to tissue metabolic alterations and may contribute to a non-invasive clinical investigation of injuries such as skin lesions. These lesions and the possible areas where they may develop can be interrogated using fluorescence lifetime spectroscopy taking into account the variability of skin phototypes and the changes related to melanin, collagen and elastin, endogenous fluorophores which have emissions that spectrally overlap to the NADH and FAD emission. The objective of this study is to assess the variation on fluorescence lifetimes of normal skin at sun exposed and non-exposed areas and associate this variation to the photoaging process.

  2. Optical fluorescence spectroscopy to detect hepatic necrosis after normothermic ischemia: animal model

    Science.gov (United States)

    Romano, Renan A.; Vollet-Filho, Jose D.; Pratavieira, Sebastião.; Fernandez, Jorge L.; Kurachi, Cristina; Bagnato, Vanderlei S.; Castro-e-Silva, Orlando; Sankarankutty, Ajith K.

    2015-06-01

    Liver transplantation is a well-established treatment for liver failure. However, the success of the transplantation procedure depends on liver graft conditions. The tissue function evaluation during the several transplantation stages is relevant, in particular during the organ harvesting, when a decision is made concerning the viability of the graft. Optical fluorescence spectroscopy is a good option because it is a noninvasive and fast technique. A partial normothermic hepatic ischemia was performed in rat livers, with a vascular occlusion of both median and left lateral lobes, allowing circulation only for the right lateral lobe and the caudate lobe. Fluorescence spectra under excitation at 532 nm (doubled frequency Nd:YAG laser) were collected using a portable spectrometer (USB2000, Ocean Optics, USA). The fluorescence emission was collected before vascular occlusion, after ischemia, and 24 hours after reperfusion. A morphometric histology analysis was performed as the gold standard evaluation - liver samples were analyzed, and the percentage of necrotic tissue was obtained. The results showed that changes in the fluorescence emission after ischemia can be correlated with the amount of necrosis evaluated by a morphometric analysis, the Pearson correlation coefficient of the generated model was 0.90 and the root mean square error was around 20%. In this context, the laser-induced fluorescence spectroscopy technique after normothermic ischemia showed to be a fast and efficient method to differentiate ischemic injury from viable tissues.

  3. Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging.

    Science.gov (United States)

    Yankelevich, Diego R; Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Elson, Daniel S; Marcu, Laura

    2014-03-01

    The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 μm diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores.

  4. Single-atom electron energy loss spectroscopy of light elements

    OpenAIRE

    Senga, Ryosuke; Suenaga, Kazu

    2015-01-01

    Light elements such as alkali metal (lithium, sodium) or halogen (fluorine, chlorine) are present in various substances and indeed play significant roles in our life. Although atomic behaviours of these elements are often a key to resolve chemical or biological activities, they are hardly visible in transmission electron microscope because of their smaller scattering power and higher knock-on probability. Here we propose a concept for detecting light atoms encaged in a nanospace by means of e...

  5. Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Adelaide; De Beule, Pieter A. A., E-mail: pieter.de-beule@inl.int [Applied Nano-Optics Laboratory, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal); Martins, Marco [Nano-ICs Group, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal)

    2015-09-15

    Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate.

  6. Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

    International Nuclear Information System (INIS)

    Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate

  7. Strengths and Weaknesses of Recently Engineered Red Fluorescent Proteins Evaluated in Live Cells Using Fluorescence Correlation Spectroscopy

    Science.gov (United States)

    Siegel, Amanda P.; Baird, Michelle A.; Davidson, Michael W.; Day, Richard N.

    2013-01-01

    The scientific community is still looking for a bright, stable red fluorescent protein (FP) as functional as the current best derivatives of green fluorescent protein (GFP). The red FPs exploit the reduced background of cells imaged in the red region of the visible spectrum, but photophysical short comings have limited their use for some spectroscopic approaches. Introduced nearly a decade ago, mCherry remains the most often used red FP for fluorescence correlation spectroscopy (FCS) and other single molecule techniques, despite the advent of many newer red FPs. All red FPs suffer from complex photophysics involving reversible conversions to a dark state (flickering), a property that results in fairly low red FP quantum yields and potential interference with spectroscopic analyses including FCS. The current report describes assays developed to determine the best working conditions for, and to uncover the shortcoming of, four recently engineered red FPs for use in FCS and other diffusion and spectroscopic studies. All five red FPs assayed had potential shortcomings leading to the conclusion that the current best red FP for FCS is still mCherry. The assays developed here aim to enable the rapid evaluation of new red FPs and their smooth adaptation to live cell spectroscopic microscopy and nanoscopy. PMID:24129172

  8. Membrane mobility and microdomain association of the dopamine transporter studied with fluorescence correlation spectroscopy and fluorescence recovery after photobleaching

    DEFF Research Database (Denmark)

    Adkins, Erika M; Samuvel, Devadoss J; Fog, Jacob U;

    2007-01-01

    To investigate microdomain association of the dopamine transporter (DAT), we employed FCS (fluorescence correlation spectroscopy) and FRAP (fluorescence recovery after photobleaching). In non-neuronal cells (HEK293), FCS measurements revealed for the YFP-DAT (DAT tagged with yellow fluorescent pr...... altering DAT surface expression. In summary, we propose that association of the DAT with lipid microdomains in the plasma membrane and/or the cytoskeleton serves to regulate both the lateral mobility of the transporter and its transport capacity....... protein) a diffusion coefficient (D) of approximately 3.6 x 10(-9) cm2/s, consistent with a relatively freely diffusible protein. In neuronally derived cells (N2a), we were unable to perform FCS measurements on plasma membrane-associated protein due to photobleaching, suggesting partial immobilization...... the cytoskeleton-disrupting agent cytochalasin D and the cholesterol-depleting agent methyl-beta-cyclodextrin (mbetaCD) increased the lateral mobility of the YFP-DAT but not that of the EGFP-EGFR. The DAT associated in part with membrane raft markers both in the N2a cells and in rat striatal synaptosomes...

  9. Membrane mobility and microdomain association of the dopaminetransporter studied with fluorescence correlation spectroscopy and fluorescence recovery after photobleaching

    DEFF Research Database (Denmark)

    Adkins, Erika; Samuvel, Devadoss; Fog, Jacob;

    2007-01-01

    To investigate microdomain association of the dopamine transporter (DAT), we employed FCS (fluorescence correlation spectroscopy) and FRAP (fluorescence recovery after photobleaching). In non-neuronal cells (HEK293), FCS measurements revealed for the YFP-DAT (DAT tagged with yellow fluorescent pr...... surface expression. In summary, we propose that association of the DAT with lipid microdomains in the plasma membrane and/or the cytoskeleton serves to regulate both the lateral mobility of the transporter and its transport capacity...... protein) a diffusion coefficient (D) of ~3.6 × 10-9 cm2/s, consistent with a relatively freely diffusible protein. In neuronally derived cells (N2a), we were unable to perform FCS measurements on plasma membrane-associated protein due to photobleaching, suggesting partial immobilization...... the cytoskeleton-disrupting agent cytochalasin D and the cholesterol-depleting agent methyl-beta-cyclodextrin (mbCD) increased the lateral mobility of the YFP-DAT but not that of the EGFP-EGFR. The DAT associated in part with membrane raft markers both in the N2a cells and in rat striatal synaptosomes as assessed...

  10. Photofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region via superexcited states studied by fluorescence spectroscopy

    Science.gov (United States)

    Wasowicz, Tomasz J.; Kivimäki, Antti; Dampc, Marcin; Coreno, Marcello; de Simone, Monica; Zubek, Mariusz

    2011-03-01

    Photofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region, producing excited atomic and molecular fragments, has been studied over the energy range 14-68 eV using photon-induced fluorescence spectroscopy. Excited hydrogen atoms H(n), n = 3-11, have been detected by observation of the Hα to Hı lines of the Balmer series. The diatomic CH(A2Δ), CH(B2Σ-) and C2(d3Πg) fragments, which are excited to low vibrational and high rotational levels are identified by their A2Δ→X2Πr, B2Σ-→X2Πr and d3Πg→a3Πu emission bands, respectively. Dissociation efficiency curves for CH(A2Δ) and H(n), n = 3-7, have been obtained in the photon energy ranges from their appearance thresholds up to 68 eV. The appearance energies for CH(A2Δ) and H(n), n = 3-7, have been determined and are compared with estimated fragmentation energy limits in order to discuss the possible fragmentation processes. In the present studies, superexcited states of tetrahydrofuran are found, which dissociate into the above excited atomic and molecular fragments.

  11. Ultrafast Energy Transfer in Artificial Antenna Molecule Measured by Transient Fluorescence Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Hai-long Chen; Yu-xiang Weng; Xi-you Li

    2011-01-01

    We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from a model fitting into the transient absorption ex perimental data. Here we present a direct ultrafast fluorescence quenching measurement by employing fs time-resolved transient fluorescence spectroscopy based on noncollinear optical parametric amplification technique. The rapid decay of the monomer's emission due to energy transfer was observed directly with a time constant of about 0.82 ps, in good agreement with the previous result.

  12. Host-Guest Complexation Studied by Fluorescence Correlation Spectroscopy: Adamantane–Cyclodextrin Inclusion

    Directory of Open Access Journals (Sweden)

    Wajih Al-Soufi

    2010-01-01

    Full Text Available The host-guest complexation between an Alexa 488 labelled adamantane derivative and β-cyclodextrin is studied by Fluorescence Correlation Spectroscopy (FCS. A 1:1 complex stoichiometry and a high association equilibrium constant of K = 5.2 × 104 M-1 are obtained in aqueous solution at 25 °C and pH = 6. The necessary experimental conditions are discussed. FCS proves to be an excellent method for the determination of stoichiometry and association equilibrium constant of this type of complexes, where both host and guest are nonfluorescent and which are therefore not easily amenable to standard fluorescence spectroscopic methods.

  13. Rapid detection of authenticity and adulteration of walnut oil by FTIR and fluorescence spectroscopy: a comparative study.

    Science.gov (United States)

    Li, Bingning; Wang, Haixia; Zhao, Qiaojiao; Ouyang, Jie; Wu, Yanwen

    2015-08-15

    Fourier transform infrared (FTIR) and fluorescence spectroscopy combined with soft independent modeling of class analogies (SIMCA) and partial least square (PLS) were used to detect the authenticity of walnut oil and adulteration amount of soybean oil in walnut oil. A SIMCA model of FTIR spectra could differentiate walnut oil and other oils into separate categories; the classification limit of soybean oil in walnut oil was 10%. Fluorescence spectroscopy could differentiate oil composition by the peak position and intensity of emission spectrum without multivariate analysis. The classification limit of soybean oil adulterated in walnut oil by fluorescence spectroscopy was below 5%. The deviation of the prediction model for fluorescence spectra was lower than that for FTIR spectra. Fluorescence spectroscopy was more applicable than FTIR in the adulteration detection of walnut oil, both from the determination limit and prediction deviation.

  14. Rapid detection of authenticity and adulteration of walnut oil by FTIR and fluorescence spectroscopy: a comparative study.

    Science.gov (United States)

    Li, Bingning; Wang, Haixia; Zhao, Qiaojiao; Ouyang, Jie; Wu, Yanwen

    2015-08-15

    Fourier transform infrared (FTIR) and fluorescence spectroscopy combined with soft independent modeling of class analogies (SIMCA) and partial least square (PLS) were used to detect the authenticity of walnut oil and adulteration amount of soybean oil in walnut oil. A SIMCA model of FTIR spectra could differentiate walnut oil and other oils into separate categories; the classification limit of soybean oil in walnut oil was 10%. Fluorescence spectroscopy could differentiate oil composition by the peak position and intensity of emission spectrum without multivariate analysis. The classification limit of soybean oil adulterated in walnut oil by fluorescence spectroscopy was below 5%. The deviation of the prediction model for fluorescence spectra was lower than that for FTIR spectra. Fluorescence spectroscopy was more applicable than FTIR in the adulteration detection of walnut oil, both from the determination limit and prediction deviation. PMID:25794716

  15. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    KAUST Repository

    Hoffman, A. S.

    2016-07-26

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  16. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres.

    Science.gov (United States)

    Hoffman, A S; Debefve, L M; Bendjeriou-Sedjerari, A; Ouldchikh, S; Bare, Simon R; Basset, J-M; Gates, B C

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities-to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions-to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported. PMID:27475549

  17. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    Science.gov (United States)

    Hoffman, A. S.; Debefve, L. M.; Bendjeriou-Sedjerari, A.; Ouldchikh, S.; Bare, Simon R.; Basset, J.-M.; Gates, B. C.

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  18. Diode-Laser Induced Fluorescence Spectroscopy of an Optically Thick Plasma in Combination with Laser Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    S. Nomura

    2013-01-01

    Full Text Available Distortion of laser-induced fluorescence profiles attributable to optical absorption and saturation broadening was corrected in combination with laser absorption spectroscopy in argon plasma flow. At high probe-laser intensity, saturated absorption profiles were measured to correct probe-laser absorption. At low laser intensity, nonsaturated absorption profiles were measured to correct fluorescence reabsorption. Saturation broadening at the measurement point was corrected using a ratio of saturated to non-saturated broadening. Observed LIF broadening and corresponding translational temperature without correction were, respectively, 2.20±0.05 GHz and 2510±100 K and corrected broadening and temperature were, respectively, 1.96±0.07 GHz and 1990±150 K. Although this correction is applicable only at the center of symmetry, the deduced temperature agreed well with that obtained by LAS with Abel inversion.

  19. Far-field infrared super-resolution microscopy using picosecond time-resolved transient fluorescence detected IR spectroscopy

    Science.gov (United States)

    Sakai, Makoto; Kawashima, Yasutake; Takeda, Akihiro; Ohmori, Tsutomu; Fujii, Masaaki

    2007-05-01

    A new far-field infrared super-resolution microscopy combining laser fluorescence microscope and picosecond time-resolved transient fluorescence detected IR (TFD-IR) spectroscopy is proposed. TFD-IR spectroscopy is a kind of IR-visible/UV double resonance spectroscopy, and detects IR transitions by the transient fluorescence due to electronic transition originating from vibrationally excited level populated by IR light. IR images of rhodamine-6G solution and of fluorescent beads were clearly observed by monitoring the transient fluorescence. Super-resolution twice higher than the diffraction limit for IR light was achieved. The IR spectrum due to the transient fluorescence was also measured from spatial domains smaller than the diffraction limit.

  20. Noise spectroscopy with large clouds of cold atoms

    Science.gov (United States)

    Kashanian, Samir Vartabi; Eloy, Aurélien; Guerin, William; Lintz, Michel; Fouché, Mathilde; Kaiser, Robin

    2016-10-01

    Noise measurement is a powerful tool to investigate many phenomena from laser characterization to quantum behavior of light. In this paper, we report on intensity noise measurements obtained when a laser beam is transmitted through a large cloud of cold atoms. While this measurement could possibly be used to investigate complex processes such as the influence of atomic motion, one is first limited by the conversion of the intrinsic laser frequency noise to intensity noise via the atomic resonance. This conversion is studied here in detail. We show that, while experimental intensity noise spectra collapse onto the same curve at low Fourier frequencies, some differences appear at higher frequencies when the probe beam is detuned from the center of the resonance line. A simple model, based on a mean-field approach, which corresponds to describing the atomic cloud by a dielectric susceptibility, is sufficient to understand the main features. Using this model, the noise spectra allow extracting some quantitative information on the laser noise as well as on the atomic sample.

  1. Precision Spectroscopy of Atomic Hydrogen and the Proton Size Puzzle

    Science.gov (United States)

    Udem, Thomas

    2016-05-01

    Precise determination of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state. Its transition frequency has now been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference. A recent measurement of the Lamb shift in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct. We hope to contribute to the resolution of this so called `proton size puzzle' by providing additional experimental input from the hydrogen side.

  2. Spectroscopy of cold rubidium Rydberg atoms for applications in quantum information

    CERN Document Server

    Ryabtsev, I I; Tretyakov, D B; Entin, V M; Yakshina, E A

    2016-01-01

    Atoms in highly excited (Rydberg) states have a number of unique properties which make them attractive for applications in quantum information. These are large dipole moments, lifetimes and polarizabilities, as well as strong long-range interactions between Rydberg atoms. Experimental methods of laser cooling and precision spectroscopy enable the trapping and manipulation of single Rydberg atoms and applying them for practical implementation of quantum gates over qubits of a quantum computer based on single neutral atoms in optical traps. In this paper, we give a review of the experimental and theoretical work performed by the authors at the Rzhanov Institute of Semiconductor Physics SB RAS and Novosibirsk State University on laser and microwave spectroscopy of cold Rb Rydberg atoms in a magneto-optical trap and on their possible applications in quantum information. We also give a brief review of studies done by other groups in this area.

  3. Plasma jet desorption atomization-atomic fluorescence spectrometry and its application to mercury speciation by coupling with thin layer chromatography.

    Science.gov (United States)

    Liu, Zhifu; Zhu, Zhenli; Zheng, Hongtao; Hu, Shenghong

    2012-12-01

    A novel plasma jet desorption atomization (PJDA) source was developed for atomic fluorescence spectrometry (AFS) and coupled on line with thin layer chromatography (TLC) for mercury speciation. An argon dielectric barrier discharge plasma jet, which is generated inside a 300 μm quartz capillary, interacts directly with the sample being analyzed and is found to desorb and atomize surface mercury species rapidly. The effectiveness of this PJDA surface sampling technique was demonstrated by measuring AFS signals of inorganic Hg(2+), methylmercury (MeHg), and phenylmercury (PhHg) deposited directly on TLC plate. The detection limits of the proposed PJDA-AFS method for inorganic Hg(2+), MeHg, and PhHg were 0.51, 0.29, and 0.34 pg, respectively, and repeatability was 4.7%, 2.2%, and 4.3% for 10 pg Hg(2+), MeHg, and PhHg. The proposed PJDA-AFS was also successfully coupled to TLC for mercury speciation. Under optimized conditions, the measurements of mercury dithizonate (Hg-D), methylmercury dithizonate (MeHg-D), and phenylmercury dithizonate (PhHg-D) could be achieved within 3 min with detection limits as low as 8.7 pg. The combination of TLC with PJDA-AFS provides a simple, cost-effective, relatively high-throughput way for mercury speciation. PMID:23153091

  4. Fluorescence excitation-emission matrix spectroscopy of vitiligo skin in vivo (Conference Presentation)

    Science.gov (United States)

    Zhao, Jianhua; Richer, Vincent; Al Jasser, Mohammed; Zandi, Soodabeh; Kollias, Nikiforos; Kalia, Sunil; Zeng, Haishan; Lui, Harvey

    2016-02-01

    Fluorescence signals depend on the intensity of the exciting light, the absorption properties of the constituent molecules, and the efficiency with which the absorbed photons are converted to fluorescence emission. The optical features and appearance of vitiligo have been explained primarily on the basis of reduced epidermal pigmentation, which results in abnormal white patches on the skin. The objective of this study is to explore the fluorescence properties of vitiligo and its adjacent normal skin using fluorescence excitation-emission matrix (EEM) spectroscopy. Thirty five (35) volunteers with vitiligo were acquired using a double-grating spectrofluorometer with excitation and emission wavelengths of 260-450 nm and 300-700 nm respectively. As expected, the most pronounced difference between the spectra obtained from vitiligo lesions compared to normally pigmented skin was that the overall fluorescence was much higher in vitiligo; these differences increased at shorter wavelengths, thus matching the characteristic spectral absorption of epidermal melanin. When comparing the fluorescence spectra from vitiligo to normal skin we detected three distinct spectral bands centered at 280nm, 310nm, and 335nm. The 280nm band may possibly be related to inflammation, whereas the 335 nm band may arise from collagen or keratin cross links. The source of the 310 nm band is uncertain; it is interesting to note its proximity to the 311 nm UV lamps used for vitiligo phototherapy. These differences are accounted for not only by changes in epidermal pigment content, but also by other optically active cutaneous biomolecules.

  5. Fluorescence (TALIF) measurement of atomic hydrogen concentration in a coplanar surface dielectric barrier discharge

    Science.gov (United States)

    Mrkvičková, M.; Ráheľ, J.; Dvořák, P.; Trunec, D.; Morávek, T.

    2016-10-01

    Spatially and temporally resolved measurements of atomic hydrogen concentration above the dielectric of coplanar barrier discharge are presented for atmospheric pressure in 2.2% H2/Ar. The measurements were carried out in the afterglow phase by means of two-photon absorption laser-induced fluorescence (TALIF). The difficulties of employing the TALIF technique in close proximity to the dielectric surface wall were successfully addressed by taking measurements on a suitable convexly curved dielectric barrier, and by proper mathematical treatment of parasitic signals from laser-surface interactions. It was found that the maximum atomic hydrogen concentration is situated closest to the dielectric wall from which it gradually decays. The maximum absolute concentration was more than 1022 m-3. In the afterglow phase, the concentration of atomic hydrogen above the dielectric surface stays constant for a considerable time (10 μs-1 ms), with longer times for areas situated farther from the dielectric surface. The existence of such a temporal plateau was explained by the presented 1D model: the recombination losses of atomic hydrogen farther from the dielectric surface are compensated by the diffusion of atomic hydrogen from regions close to the dielectric surface. The fact that a temporal plateau exists even closest to the dielectric surface suggests that the dielectric surface acts as a source of atomic hydrogen in the afterglow phase.

  6. Investigation of hydrogen atom addition to vinyl monomers by time resolved ESR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Beckert, D.; Mehler, K.

    1983-07-01

    By means of time resolved ESR spectroscopy in the microsecond time scale the H atom addition to different vinyl monomers was investigated. The H atoms produced by pulse radiolysis of aqueous solutions show a strong recombination CIDEP effect which also allows the recombination rate constant of H atoms to be determined. By analysis of ESR time profiles with the modified Bloch equations the relaxation times T/sub 1/, T/sub 2/, the polarization factors and the chemical rate constants with scavengers were obtained. Besides the H atom addition rate constants to different vinyl monomers the structure of the monomer radical was determined for acrylic acid.

  7. Quantitative Diffuse Reflectance and Fluorescence Spectroscopy: A Tool to Monitor Tumor Physiology In Vivo

    OpenAIRE

    Palmer, Gregory M.; Viola, Ronald J.; Schroeder, Thies; Yarmolenko, Pavel S.; Dewhirst, Mark W.; Ramanujam, Nirmala

    2009-01-01

    This study demonstrates the use of optical spectroscopy for monitoring tumor oxygenation and metabolism in response to hyperoxic gas breathing. Hemoglobin saturation and redox ratio were quantified for a set of 14 and 9 mice, respectively, measured at baseline and during carbogen breathing (95% O2, 5% CO2). In particular, significant increases in hemoglobin saturation and fluorescence redox ratio were observed upon carbogen breathing. These data were compared to that obtained concurrently usi...

  8. Detection of hyaluronidase activity using fluorescein labeled hyaluronic acid and fluorescence correlation spectroscopy

    OpenAIRE

    Rich, Ryan M.; Mummert, Mark; Foldes-Papp, Zeno; Gryczynski, Zygmunt; Borejdo, Julian; Gryczynski, Ignacy; Fudala, Rafal

    2012-01-01

    The over-expression of hyaluronidase has been observed in many types of cancer, suggesting that it may have utility for diagnosis. Here we present a technique for the detection of hyaluronidase using Fluorescence Correlation Spectroscopy (FCS). Hyaluronan macromolecules (HAs) have been heavily labeled with fluorescein amine resulting in strong self-quenching. In the presence of hyaluronidase, HA is cleaved into smaller, fluorescein-labeled fragments and the self-quenching is released. Such cl...

  9. Fluorescence spectroscopy: a rapid tool for assessing tetracycline resistance in Bifidobacterium longum

    OpenAIRE

    Ammor, Mohammed Salim; Flórez García, Ana Belén; Margolles Barros, Abelardo; Mayo Pérez, Baltasar

    2006-01-01

    [EN]The tetracycline uptake kinetics of 35 Bifidobacterium longum strains isolated from the human gastrointestinal tract were examined by fluorescence spectroscopy, and the suitability of the technique as a screening tool of tetracycline resistance or susceptibility was determined. The strains were first grouped into three classes based on their corresponding minimum inhibitory concentrations (MICs) of tetracycline, as established by the microdilution method: susceptible (MICs ≤1 µg mL-1), se...

  10. Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation.

    Science.gov (United States)

    Zu, Wenchuan; Wang, Zhenghao

    2016-03-01

    A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL(-1) methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH3(+) solutions were in the range of 0.2-5 ng mL(-1)(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88×10(-3)ng mL(-1) and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL(-1) standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7-45.8 ng g(-1). The recoveries for methylmercury spiked samples were found to be in the range of 87.6-103.6% and the relative standard deviations below 5% (n=6) were acquired, which showed this method was feasible for real sample analysis. PMID:26615576

  11. In vivo detection of epileptic brain tissue using static fluorescence and diffuse reflectance spectroscopy.

    Science.gov (United States)

    Yadav, Nitin; Bhatia, Sanjiv; Ragheb, John; Mehta, Rupal; Jayakar, Prasanna; Yong, William; Lin, Wei-Chiang

    2013-02-01

    Diffuse reflectance and fluorescence spectroscopy are used to detect histopathological abnormalities of an epileptic brain in a human subject study. Static diffuse reflectance and fluorescence spectra are acquired from normal and epileptic brain areas, defined by electrocorticography (ECoG), from pediatric patients undergoing epilepsy surgery. Biopsy specimens are taken from the investigated sites within an abnormal brain. Spectral analysis reveals significant differences in diffuse reflectance spectra and the ratio of fluorescence and diffuse reflectance spectra from normal and epileptic brain areas defined by ECoG and histology. Using these spectral differences, tissue classification models with accuracy above 80% are developed based on linear discriminant analysis. The differences between the diffuse reflectance spectra from the normal and epileptic brain areas observed in this study are attributed to alterations in the static hemodynamic characteristics of an epileptic brain, suggesting a unique association between the histopathological and the hemodynamic abnormalities in an epileptic brain.

  12. Ultra-sensitive fluorescence spectroscopy of isolated surface-adsorbed molecules using an optical nanofiber.

    Science.gov (United States)

    Stiebeiner, A; Rehband, O; Garcia-Fernandez, R; Rauschenbeutel, A

    2009-11-23

    The strong radial confinement and the pronounced evanescent field of the guided light in optical nanofibers yield favorable conditions for ultra-sensitive surface spectroscopy of molecules deposited on the fiber. Using the guided mode of the nanofiber for both excitation and fluorescence collection, we present spectroscopic measurements on 3,4,9,10-perylenetetracarboxylic dianhydride molecules (PTCDA) at ambient conditions. Surface coverages as small as 1 per thousand of a compact monolayer still give rise to fluorescence spectra with a good signal to noise ratio. Moreover, we analyze and quantify the self-absorption effects due to reabsorption of the emitted fluorescence light by circumjacent surface-adsorbed molecules distributed along the fiber waist. PMID:19997412

  13. Fluorescence correlation spectroscopy for the characterization of membranes : A short review

    Directory of Open Access Journals (Sweden)

    Hwang, L.C.

    2002-01-01

    Full Text Available Fluorescence correlation spectroscopy (FCS is a highly sensitive fluorescence microscopy technique that can be used to probe a wide range of biophysical processes including diffusion, Ligand-receptor binding and molecular aggregation on artificial and cell membranes. FCS is able to measure very small volumes at nanomolar concentrations. In this work, we review the different types of diffusion on cell membranes,describe the theory of FCS and illustrate several of its applications for the characterization of membranes and membrane associated proteins. For comparison with other techniques we discuss the differences of FCS and fluorescence recovery after photobleaching (FRAP,a widely used technique for diffusion measurements on membranes, in detail

  14. Visible-super-resolution infrared microscopy using saturated transient fluorescence detected infrared spectroscopy

    Science.gov (United States)

    Bokor, Nándor; Inoue, Keiichi; Kogure, Satoshi; Fujii, Masaaki; Sakai, Makoto

    2010-02-01

    A scanning visible-super-resolution microscope based on the saturation behaviour of transient fluorescence detected infrared (TFD-IR) spectroscopy is proposed. A Gaussian IR beam, a Gaussian visible beam and a Laguerre-Gaussian (LG) visible beam are used to obtain two separate two-color excitation fluorescence (2CF) images of the sample. The final image is obtained as the difference between the two recorded images. If the peak intensity of the LG beam is high enough to induce saturation in the fluorescence signal, the image can, in principle, have unlimited spatial resolution. A ˜3-fold improvement in transverse resolution over the visible diffraction limit (and far exceeding the IR diffraction limit) is easily achievable in present experimental setups.

  15. Fluorescence spectroscopy for assessment of liver transplantation grafts concerning graft viability and patient survival

    Science.gov (United States)

    Vollet Filho, José D.; da Silveira, Marina R.; Castro-e-Silva, Orlando; Bagnato, Vanderlei S.; Kurachi, Cristina

    2015-06-01

    Evaluating transplantation grafts at harvest is essential for its success. Laser-induced fluorescence spectroscopy (LIFS) can help monitoring changes in metabolic/structural conditions of tissue during transplantation. The aim of the present study is to correlate LIFSobtained spectra of human hepatic grafts during liver transplantation with post-operative patients' mortality rate and biochemical parameters, establishing a method to exclude nonviable grafts before implantation. Orthotopic liver transplantation, piggyback technique was performed in 15 patients. LIFS was performed under 408nm excitation. Collection was performed immediately after opening donor's abdominal cavity, after cold perfusion, end of back-table period, and 5 min and 1 h after warm perfusion at recipient. Fluorescence information was compared to lactate, creatinine, bilirubin and INR levels and to survival status. LIFS was sensitive to liver changes during transplantation stages. Study-in-progress; initial results indicate correlation between fluorescence and life/death status of patients.

  16. Freshness estimation of intact frozen fish using fluorescence spectroscopy and chemometrics of excitation-emission matrix.

    Science.gov (United States)

    ElMasry, Gamal; Nagai, Hiroto; Moria, Keisuke; Nakazawa, Naho; Tsuta, Mizuki; Sugiyama, Junichi; Okazaki, Emiko; Nakauchi, Shigeki

    2015-10-01

    The current study attempted to provide a convenient, non-invasive and time-saving method to estimate the freshness of intact horse mackerel (Trachurus japonicus) fish in a frozen state using autofluorescence spectroscopy in tandem with multivariate analysis of fluorescence excitation-emission matrices (EEM). The extracted fluorescence data from different freshness conditions were pretreated, masked and reorganized to resolve fish fluorescence spectra from overlapping signals and scattering profiles for detecting and characterizing freshness changes. The real freshness values of the examined fish samples were then traditionally determined by the hard chemical analysis using the high performance liquid chromatography (HPLC) method and expressed as K-values. The fluorescence EEM data and the real freshness values were modeled using partial least square (PLS) regression and a novel algorithm was proposed to identify the ideal combinations of excitation and emission wavelengths being used as perfect predictors. The results revealed that freshness of frozen fish could be accurately predicted with R(2) of 0.89 and root mean square error estimated by cross validation (RMSECV) of 9.66%. This work substantially demonstrated that the autofluorescence spectroscopy associated with the proposed technical approaches has a high potential in non-destructive sensing of fish freshness in the frozen state. PMID:26078142

  17. Blood perfusion and pH monitoring in organs by laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Vari, Sandor G.; Papazoglou, Theodore G.; Pergadia, Vani R.; Stavridi, Marigo; Snyder, Wendy J.; Papaioannou, Thanassis; Duffy, J. T.; Weiss, Andrew B.; Thomas, Reem; Grundfest, Warren S.

    1994-01-01

    Sensitivity of laser-induced fluorescence spectroscopy (LIFS) in detecting a change in tissue pH, and blood perfusion was determined. Rabbits were anesthetized, paralyzed, and mechanically ventilated. The arterial and venous blood supplies of the kidney were isolated and ligated to alter the perfusion. The femoral artery was cannulated to extract samples for blood gas analysis. A 308-nm XeCl was used as an excitation source. A 600 micrometers core diameter fiber was used for fluorescence acquisition, and the spectra analyzed by an optical multichannel analyzer (EG & G, OMA III). the corresponding intensity ratio R equals INADH / ICOLL was used as an index for respiratory acidosis. Blood perfusion was assessed using the following algorithm: (IELAS minus ICOLL) divided by (INADH minus ICOLL). The intensity ratio linearly decreased with the reduction of blood perfusion. When we totally occluded the artery the ratio decreased tenfold when compared to the ratio of a fully perfused kidney. Results of monitoring blood acidosis by laser-induced fluorescence spectroscopy shows a significant trend between pH and intensity ratio. Since all the slopes were negative, there is an obvious significant correlation between the pH and NADH.COLLAGEN RATIO. Blue-light-induced fluorescence measurements and ratio fluorometry is a sensitive method for monitoring blood perfusion and acidity or alkalinity of an organ.

  18. Spoilage of foods monitored by native fluorescence spectroscopy with selective excitation wavelength

    Science.gov (United States)

    Pu, Yang; Wang, Wubao; Alfano, Robert R.

    2015-03-01

    The modern food processing and storage environments require the real-time monitoring and rapid microbiological testing. Optical spectroscopy with selective excitation wavelengths can be the basis of a novel, rapid, reagent less, noncontact and non-destructive technique for monitoring the food spoilage. The native fluorescence spectra of muscle foods stored at 2-4°C (in refrigerator) and 20-24°C (in room temperature) were measured as a function of time with a selective excitation wavelength of 340nm. The contributions of the principal molecular components to the native fluorescence spectra of meat were measured spectra of each fluorophore: collagen, reduced nicotinamide adenine dinucleotide (NADH), and flavin. The responsible components were extracted using a method namely Multivariate Curve Resolution with Alternating Least-Squares (MCR-ALS). The native fluorescence combined with MCR-ALS can be used directly on the surface of meat to produce biochemically interpretable "fingerprints", which reflects the microbial spoilage of foods involved with the metabolic processes. The results show that with time elapse, the emission from NADH in meat stored at 24°C increases much faster than that at 4°C. This is because multiplying of microorganisms and catabolism are accompanied by the generation of NADH. This study presents changes of relative content of NADH may be used as criterion for detection of spoilage degree of meat using native fluorescence spectroscopy.

  19. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya, E-mail: divya@chem.unipune.ac.in

    2015-05-15

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu{sup 2+}, Fe{sup 2+}, Ni{sup 2+} and Zn{sup 2+} in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu{sup 2+}, Fe{sup 2+} and Ni{sup 2+} caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe{sup 2+}, Cu{sup 2+}, Ni{sup 2+} and Zn{sup 2+}. • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions.

  20. Applications of Fluorescence Spectroscopy for dissolved organic matter characterization in wastewater treatment plants

    Science.gov (United States)

    Goffin, Angélique; Guérin, Sabrina; Rocher, Vincent; Varrault, Gilles

    2016-04-01

    Dissolved organic matter (DOM) influences wastewater treatment plants efficiency (WTTP): variations in its quality and quantity can induce a foaming phenomenon and a fouling event inside biofiltration processes. Moreover, in order to manage denitrification step (control and optimization of the nitrate recirculation), it is important to be able to estimate biodegradable organic matter quantity before biological treatment. But the current methods used to characterize organic matter quality, like biological oxygen demand are laborious, time consuming and sometimes not applicable to directly monitor organic matter in situ. In the context of MOCOPEE research program (www.mocopee.com), this study aims to assess the use of optical techniques, such as UV-Visible absorbance and more specifically fluorescence spectroscopy in order to monitor and to optimize process efficiency in WWTP. Fluorescence excitation-emission matrix (EEM) spectroscopy was employed to prospect the possibility of using this technology online and in real time to characterize dissolved organic matter in different effluents of the WWTP Seine Centre (240,000 m3/day) in Paris, France. 35 sewage water influent samples were collected on 10 days at different hours. Data treatment were performed by two methods: peak picking and parallel factor analysis (PARAFAC). An evolution of DOM quality (position of excitation - emission peaks) and quantity (intensity of fluorescence) was observed between the different treatment steps (influent, primary treatment, biological treatment, effluent). Correlations were found between fluorescence indicators and different water quality key parameters in the sewage influents. We developed different multivariate linear regression models in order to predict a variety of water quality parameters by fluorescence intensity at specific excitation-emission wavelengths. For example dissolved biological oxygen demand (r2=0,900; p<0,0001) and ammonium concentration (r2=0,898; p<0

  1. X-ray spectroscopy of kaonic atoms at SIDDHARTA

    Directory of Open Access Journals (Sweden)

    Cargnelli M.

    2014-06-01

    Full Text Available The X-ray measurements of kaonic atoms play an important role for understanding the low-energy QCD in the strangeness sector. The SIDDHARTA experiment studied the X-ray transitions of 4 light kaonic atoms (H, D, 3He, and 4He using the DAFNE electron-positron collider at LNF (Italy. Most precise values of the shift and width of the kaonic hydrogen 1s state were determined, which have been now used as fundamental information for the low-energy K−p interaction in theoretical studies. An upper limit of the X-ray yield of kaonic deuterium was derived, important for future K−d experiments. The shifts and widths of the kaonic 3He and 4He 2p states were obtained, confirming the end of the “kaonic helium puzzle”. In this contribution also the plans for new experiments of kaonic deuterium are being presented.

  2. Communication: angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets.

    Science.gov (United States)

    Hernando, Alberto; Beswick, J Alberto; Halberstadt, Nadine

    2013-12-14

    The theory of photofragments angular momentum polarization is applied to the photodetachment of an electronically excited alkali atom from a helium nanocluster (N = 200). The alignment of the electronic angular momentum of the bare excited alkali atoms produced is calculated quantum mechanically by solving the excited states coupled equations with potentials determined by density functional theory (DFT). Pronounced oscillations as a function of excitation energy are predicted for the case of Na@(He)200, in marked contrast with the absorption cross-section and angular distribution of the ejected atoms which are smooth functions of the energy. These oscillations are due to quantum interference between different coherently excited photodetachment pathways. Experimentally, these oscillations should be reflected in the fluorescence polarization and polarization-resolved photoelectron yield of the ejected atoms, which are proportional to the electronic angular momentum alignment. In addition, this result is much more general than the test case of NaHe200 studied here. It should be observable for larger droplets, for higher excited electronic states, and for other alkali as well as for alkali-earth atoms. Detection of these oscillations would show that the widely used pseudo-diatomic model can be valid beyond the prediction of absorption spectra and could help in interpreting parts of the dynamics, as already hinted by some experimental results on angular anisotropy of bare alkali fragments.

  3. Time-resolved two-photon excitation fluorescence spectroscopy and microscopy using a high repetition rate streak camera

    Institute of Scientific and Technical Information of China (English)

    LIU Li-xin; QU Ju-le; LIN Zi-yang; WANG Lei; FU Zhe; GUO Bao-ping; NIU Han-ben

    2007-01-01

    We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrumresolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time- and spectrum- resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures.Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.

  4. Cure monitoring of an epoxy-anhydride system by means of fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, D.H.; Kim, D.S.; Lee, J.K. [Kumoh National Univeristy of Technology, Kumi (Korea)

    2001-03-01

    In the present study the cure behavior of diglycidyl ether of bisphenol-A (DGEBA) using an anhydride-based hardener in the presence of N,N-dimethyl benzyl amine (BDMA) or 1-cyanoethyl-2-ethyl-4-methyl imidazole (2E4MZ-CN) as an accelerator has been monitored and interpreted from the viewpoint of photophysical properties by means of fluorescence spectroscopy. To do this, 1,3-bis-(1-pyrene)propane (BPP) was well incorporated in the epoxy resin system by mechanical blending. The BPP probe, which is very sensitive to conformational change of the molecule influenced by the surrounding medium, successfully formed intramolecular excimer fluorescence. It is susceptible to the micro-viscosity or local viscosity and molecular mobility according to the epoxy cure. The cure behavior was explained with monomer fluorescence intensity (I{sub M}), excimer fluorescence intensity (I{sub E}) and I{sub M}/I{sub E} ratio as a function of cure time, cure temperature and accelerator. The present work agreed with the previous report on the cure behavior of an epoxy-anhydride system studied using DSc or torsion pendulum method. This study also suggests that the use of fluorescence technique may provide information on cure behavior of a thermosetting resin in a low temperature region, which has not been well interpreted by other analytical methods. (author). 31 refs., 8 figs.

  5. Study of the interaction between 5-sulfosalicylic acid and bovine serum albumin by fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Juan, E-mail: zhangjuano13@126.com [Department of Chemistry, School of Basic Medical Sciences, Ningxia Medical University, Yinchuan City, Ningxia Province 750004 (China); Yan, Qianshun; Liu, Jianping; Lu, Xiaohong; Zhu, Yanshu [Department of Chemistry, School of Basic Medical Sciences, Ningxia Medical University, Yinchuan City, Ningxia Province 750004 (China); Wang, Jie; Wang, Shujing [Medical Science Research Center, Ningxia Medical University, Yinchuan City, Ningxia Province 750004 (China)

    2013-02-15

    The interaction between 5-sulfosalicylic acid (SSA) and bovine serum albumin (BSA) at pH 7.40 was studied by fluorescence and UV-vis absorption spectroscopy at different temperatures. The results revealed that SSA caused the fluorescence quenching of BSA through a static quenching procedure. The binding constant K was measured by fluorescence quenching method. The thermodynamic parameters, {Delta}H and {Delta}S, were calculated to be 23.16 kJ mol{sup -1}>0 and 162.37 J mol{sup -1} K{sup -1}>0, respectively, which suggested that the hydrophobic force played a major role in the reaction of SSA on BSA. The distance r between donor (BSA) and acceptor (SSA) was obtained according to the Foerster non-radiation energy transfer theory. The results of synchronous fluorescence spectra, three-dimensional fluorescence spectra and far-UV circular dichroism spectra showed that the interaction between BSA and SSA induced conformational changes in BSA. - Highlights: Black-Right-Pointing-Pointer Interaction of BSA with SSA was investigated by FL, UV-vis and CD spectra. Black-Right-Pointing-Pointer {Delta}H, {Delta}G, {Delta}S, K{sub q}, K{sub sv}, K and r were calculated. Black-Right-Pointing-Pointer Hydrophobic interaction played a major role in the reaction. Black-Right-Pointing-Pointer Conformation of BSA was changed in the presence of SSA.

  6. Study of the interaction between 5-sulfosalicylic acid and bovine serum albumin by fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The interaction between 5-sulfosalicylic acid (SSA) and bovine serum albumin (BSA) at pH 7.40 was studied by fluorescence and UV–vis absorption spectroscopy at different temperatures. The results revealed that SSA caused the fluorescence quenching of BSA through a static quenching procedure. The binding constant K was measured by fluorescence quenching method. The thermodynamic parameters, ΔH and ΔS, were calculated to be 23.16 kJ mol−1>0 and 162.37 J mol−1 K−1>0, respectively, which suggested that the hydrophobic force played a major role in the reaction of SSA on BSA. The distance r between donor (BSA) and acceptor (SSA) was obtained according to the Förster non-radiation energy transfer theory. The results of synchronous fluorescence spectra, three-dimensional fluorescence spectra and far-UV circular dichroism spectra showed that the interaction between BSA and SSA induced conformational changes in BSA. - Highlights: ► Interaction of BSA with SSA was investigated by FL, UV–vis and CD spectra. ► ΔH, ΔG, ΔS, Kq, Ksv, K and r were calculated. ► Hydrophobic interaction played a major role in the reaction. ► Conformation of BSA was changed in the presence of SSA.

  7. Applications of fluorescence spectroscopy for predicting percent wastewater in an urban stream

    Science.gov (United States)

    Goldman, Jami H.; Rounds, Stewart A.; Needoba, Joseph A.

    2012-01-01

    Dissolved organic carbon (DOC) is a significant organic carbon reservoir in many ecosystems, and its characteristics and sources determine many aspects of ecosystem health and water quality. Fluorescence spectroscopy methods can quantify and characterize the subset of the DOC pool that can absorb and re-emit electromagnetic energy as fluorescence and thus provide a rapid technique for environmental monitoring of DOC in lakes and rivers. Using high resolution fluorescence techniques, we characterized DOC in the Tualatin River watershed near Portland, Oregon, and identified fluorescence parameters associated with effluent from two wastewater treatment plants and samples from sites within and outside the urban region. Using a variety of statistical approaches, we developed and validated a multivariate linear regression model to predict the amount of wastewater in the river as a function of the relative abundance of specific fluorescence excitation/emission pairs. The model was tested with independent data and predicts the percentage of wastewater in a sample within 80% confidence. Model results can be used to develop in situ instrumentation, inform monitoring programs, and develop additional water quality indicators for aquatic systems.

  8. Arsenic species analysis in porewaters and sediments using hydride generation atomic fluorescence spectrometry

    Institute of Scientific and Technical Information of China (English)

    LIAO Meng-xia; DENG Tian-long

    2006-01-01

    It was observed that the atomic fluorescence emission due to As(Ⅴ) could has a 10% to 40% of fluorescence emission signal during the determination of As(Ⅲ) in the mixture of As(Ⅲ) and As(Ⅴ). Besides, interferes from heavy metals such as Pb(Ⅱ),Cu(Ⅱ) can cause severe increase of the signals as compared to the insignificant effects caused by Cd(Ⅱ), Zn(Ⅱ), Mn(Ⅱ) and Fe(Ⅲ). On the basis of further studies, the masking agent of 8-hydroxyquinoline was used as an efficient agent to eliminate interference of As(Ⅴ)emission and the heavy metal of Cu2+ and Pb2+ in the measurements of arsenic species. After a series standard additions and CRM researches, a sensitive and interference-free analytical procedure was developed for the speciation of arsenic in samples ofporewaters and sediments in Poyang Lake, China.

  9. Sub-cellular structure studied by combined atomic force-fluorescence microscopy

    Science.gov (United States)

    Trache, Andreea

    2009-03-01

    A novel experimental technique that integrates atomic force microscopy (AFM) with fluorescence imaging was used to study the role of extracellular matrix proteins in cellular organization. To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, we developed a new technology able to investigate cellular behavior at sub-cellular level that integrates an AFM with total internal reflection fluorescence (TIRF) microscopy and fast-spinning disk (FSD) confocal microscopy. Live smooth muscle cells exhibited differences in focal adhesions and actin pattern depending on the extracellular matrix used for substrate coating. Data obtained by using the AFM-optical imaging integrated technique offer novel quantitative information that allows understanding the fundamental processes of cellular reorganization in response to extracellular matrix modulation. The integrated microscope presented here is broadly applicable across a wide range of molecular dynamic studies in any adherent live cells.

  10. Modulation Transfer Spectroscopy of Ytterbium Atoms in a Hollow Cathode Lamp

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Li; XU Xin-Ye

    2011-01-01

    We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp.The dependences of its linewidth, slope and magnitude on the various experimental parameters are measured and fitted by the well-known theoretical expressions. The experimental results are in good agreement with the theoretical prediction. We have observed the Dicke narrowing effect by increasing the current of the hollow cathode lamp. It is also found that there are the optimal current and laser power to generate the better modulation transfer spectroscopy signal, which can be employed for locking the laser frequency to the atomic transition.

  11. Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb

    OpenAIRE

    Fortier, T. M.; Coq, Y Le; Stalnaker, J. E.; Ortega, D.; Diddams, S. A.; Oates, C. W.; Hollberg, L.

    2006-01-01

    We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows for two regimes of amplification, one in which many lines of the comb are amplified, and one where a single line is predominantly amplified. The output of the laser in both regimes was used to perform kilohertz-level spectroscopy. This experiment demonstrat...

  12. PETOS-BASIC programs for treating data and reporting results in atomic spectroscopy

    International Nuclear Information System (INIS)

    A PETOS-BASIC program was written which provides the off-line treatment of data in optical emission spectroscopy, flame photometry and, atomic absorption spectroscopy. Polynomial calibration functions are fitted in overlapped steps by the least squares method. The calculated concentrations in unknown samples are stored in sequential files (one per element, up to four), from which they can be read to be reported in a second program. (Author) 7 refs

  13. Magnetic field modulation spectroscopy of rubidium atoms

    Indian Academy of Sciences (India)

    S Pradhan; R Behera; A K Das

    2012-04-01

    The magnetically modulated saturation absorption profile is studied for a wide range of external DC magnetic field. The salient features of Doppler-free signal generated by laser frequency modulation and atomic energy level modulation are compared. The DC offset of the signal profile is found to be unstable as the external DC magnetic field is changed. The technical difficulty of tuning laser frequency under locked condition over a large frequency span is discussed along with possible solutions.

  14. Determination of vanadium in food and traditional Chinese medicine by graphite furnace atomic absorption spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Various experimental conditions were described for the vanadium determination by graphite furnace atomic ab-sorption spectroscopy (GFAAS). The experiments showed that when atomization took place under the conditions where thecombination of a pyrolytic coating graphite tube and fast raising temperature were used and the temperature was stable, thesignal peak shapes could be improved, the sensitivity was enhanced, and the memory effect was removed. The vanadium infood and traditional Chinese medicinal herbs can be accurately determined using the standard curve method.

  15. Multiphoton microscopy, fluorescence lifetime imaging and optical spectroscopy for the diagnosis of neoplasia

    Science.gov (United States)

    Skala, Melissa Caroline

    2007-12-01

    the ultraviolet to visible wavelength range indicated that the most diagnostic optical signals originate from sub-surface tissue layers. Optical properties extracted from these spectroscopy measurements showed a significant decrease in the hemoglobin saturation, absorption coefficient, reduced scattering coefficient and fluorescence intensity (at 400 nm excitation) in neoplastic compared to normal tissues. The results from these studies indicate that multiphoton microscopy and optical spectroscopy can non-invasively provide information on tissue structure and function in vivo that is related to tissue pathology.

  16. Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging

    International Nuclear Information System (INIS)

    The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 μm diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8–7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence

  17. Fluorescence spectroscopy for the detection of potentially malignant disorders of the oral cavity: analysis of 30 cases

    Science.gov (United States)

    Francisco, A. L. N.; Correr, W. R.; Azevedo, L. H.; Galletta, V. K.; Pinto, C. A. L.; Kowalski, L. P.; Kurachi, C.

    2014-01-01

    Oral cancer is a major health problem worldwide and although early diagnosis of potentially malignant and malignant diseases is associated with better treatment results, a large number of cancers are initially misdiagnosed, with unfortunate consequences for long-term survival. Fluorescence spectroscopy is a noninvasive modality of diagnostic approach using induced fluorescence emission in tumors that can improve diagnostic accuracy. The objective of this study was to determine the ability to discriminate between normal oral mucosa and potentially malignant disorders by fluorescence spectroscopy. Fluorescence investigation under 408 and 532 nm excitation wavelengths was performed on 60 subjects, 30 with potentially malignant disorders and 30 volunteers with normal mucosa. Data was analyzed to correlate fluorescence patterns with clinical and histopathological diagnostics. Fluorescence spectroscopy used as a point measurement technique resulted in a great variety of spectral information. In a qualitative analysis of the fluorescence spectral characteristics of each type of injury evaluated, it was possible to discriminate between normal and abnormal oral mucosa. The results show the potential use of fluorescence spectroscopy for an improved discrimination of oral disorders.

  18. Fluorescence spectroscopy for the detection of potentially malignant disorders of the oral cavity: analysis of 30 cases

    International Nuclear Information System (INIS)

    Oral cancer is a major health problem worldwide and although early diagnosis of potentially malignant and malignant diseases is associated with better treatment results, a large number of cancers are initially misdiagnosed, with unfortunate consequences for long-term survival. Fluorescence spectroscopy is a noninvasive modality of diagnostic approach using induced fluorescence emission in tumors that can improve diagnostic accuracy. The objective of this study was to determine the ability to discriminate between normal oral mucosa and potentially malignant disorders by fluorescence spectroscopy. Fluorescence investigation under 408 and 532 nm excitation wavelengths was performed on 60 subjects, 30 with potentially malignant disorders and 30 volunteers with normal mucosa. Data was analyzed to correlate fluorescence patterns with clinical and histopathological diagnostics. Fluorescence spectroscopy used as a point measurement technique resulted in a great variety of spectral information. In a qualitative analysis of the fluorescence spectral characteristics of each type of injury evaluated, it was possible to discriminate between normal and abnormal oral mucosa. The results show the potential use of fluorescence spectroscopy for an improved discrimination of oral disorders. (paper)

  19. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    CERN Document Server

    Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

  20. Electrochemical hydride generation atomic fluorescence spectrometry for detection of tin in canned foods using polyaniline-modified lead cathode

    International Nuclear Information System (INIS)

    An electrochemical hydride generation system with polyaniline-modified lead cathode was developed for tin determination by coupling with atomic fluorescence spectrometry. The tin fluorescence signal intensity was improved evidently as the polyaniline membrane could facilitate the transformation process from atomic tin to the SnH4 and prevent the aggradation of Sn atom on Pb electrode surface. The effects of experimental parameters and interferences have been studied. The limit of detection (LOD) was 1.5 ng mL-1 (3σ) and the relative standard deviation (RSD) was 3.3% for 11 consecutive measurements of 50 ng mL-1 Sn(IV) standard solution.

  1. Nuclear moments and isotopic variation of the mean square charge radii of strontium nuclei by atomic beam laser spectroscopy

    International Nuclear Information System (INIS)

    Hyperfine structure and optical isotope shift measurements have been performed on a series of stable and radioactive strontium isotopes (A = 80 to 90), including two isomers 85m and 87m. The spectroscopy applied continuous wave dye laser induced fluorescence of free atoms at λ=293.2 nm in a well collimated atomic beam. The 293.2 nm ultraviolet light was generated by frequency doubling the output of a dye laser in either a temperature tuned Ammonium Dihydrogen Arsenate (ADA) crystal or an angle tuned Lithium Iodate crystal. A special radio frequency (rf) technique was used to tune the dye laser frequency with long term stability. Radioactive Sr isotopes were produced either by neutron capture of stable strontium or by (α,xn) reactions from krypton gas. The samples were purified by an electromagnetic mass separator and their sizes were of order 100 pg, which corresponds to 1011 atoms. The observed results of the hyperfine structure components are evaluated in terms of nuclear magnetic dipole moments and electric quadrupole moments. Changes in mean square charge radii of strontium nuclei which were extracted from the isotope shift measurements, exhibit a distinct shell effect at the neutron magic number N=50. The experimental data are analysed and compared with some theoretical nuclear model predictions. The strong increase of the nuclear charge radii with decreasing neutron number of isotopes below N=50 is in agreement with the variation of the mean square deformation extracted from measured B(E2) values. (orig.)

  2. Emission, optical--optical double resonance, and excited state absorption spectroscopy of matrix isolated chromium and molybdenum atoms

    International Nuclear Information System (INIS)

    Making use of a combination of time-resolved emission, optical--optical double resonance, and excited state absorption spectroscopy, it has been possible to assign virtually all spectral features with energies below the z7P0 state of matrix isolated Cr atoms. The a5S state located at 7593 cm-1 in the free gaseous Cr atom has lifetimes of 6.32 and 5.1 s in Ar and Kr matrices, respectively. Matrix perturbations on Cr emission lines are small (-1). The dependence of nonradiative decay rates on the local density of states is elucidated. The magnitude of matrix shifts for a particular transition is correlated with the electronic configurations of ground and excited states and it is pointed out that states having only ''s'' electrons in addition to ''d'' electrons maintain their gas phase energy relationships in the matrix environment. Direct fluorescence is observed from the z7P0 level of Mo to the 7s ground state. The spin-orbit splitting of the ''relaxed'' z7P0 state is 690 cm-1, slightly lower than the 707 cm-1 splitting of the free gaseous Mo atom

  3. Photon emission spectroscopy of ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nystroem, B.

    1995-10-01

    Emission cross sections for the 1snp{sup 1}P{sub 1}-levels have been measured by photon emission spectroscopy for the collision systems He{sup +} + He at 10 keV and He{sup 2+} + He at 10-35 keV. Photon spectra of Krypton (Kr VIII) and Xenon (Xe V - IX) have also been obtained using 10q keV beams of Kr{sup q+} (q=7-9) and Xe{sup q+} (q=5-9) colliding with Helium and Argon. The Lifetimes of 3p{sup 2}P-levels in Na-like Nb are reported together with lifetime for the 3s3p{sup 3}P{sub 1}-level in Mg-like Ni, Kr, Y, Zr and Nb where this level has an intercombination transition to the ground state. 45 refs, 20 figs.

  4. Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb

    CERN Document Server

    Fortier, T M; Stalnaker, J E; Ortega, D; Diddams, S A; Oates, C W; Hollberg, L

    2006-01-01

    We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows for two regimes of amplification, one in which many lines of the comb are amplified, and one where a single line is predominantly amplified. The output of the laser in both regimes was used to perform kilohertz-level spectroscopy. This experiment demonstrates the potential for high-resolution absolute-frequency spectroscopy over the entire spectrum of the frequency comb output using a single high-finesse optical reference cavity.

  5. Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb.

    Science.gov (United States)

    Fortier, T M; Coq, Y Le; Stalnaker, J E; Ortega, D; Diddams, S A; Oates, C W; Hollberg, L

    2006-10-20

    We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows for two regimes of amplification, one in which many lines of the comb are amplified, and one where a single line is predominantly amplified. The output of the laser in both regimes was used to perform kilohertz-level spectroscopy. This experiment demonstrates the potential for high-resolution absolute-frequency spectroscopy over the entire spectrum of the frequency comb output using a single high-finesse optical reference cavity. PMID:17155398

  6. Fluorescence excitation-emission matrix spectroscopy as a tool for determining quality of sparkling wines.

    Science.gov (United States)

    Elcoroaristizabal, Saioa; Callejón, Raquel M; Amigo, Jose M; Ocaña-González, Juan A; Morales, M Lourdes; Ubeda, Cristina

    2016-09-01

    Browning in sparkling wines was assessed by the use of excitation-emission fluorescence spectroscopy combined with PARAllel FACtor analysis (PARAFAC). Four different cava sparkling wines were monitored during an accelerated browning process and subsequently storage. Fluorescence changes observed during the accelerated browning process were monitored and compared with other conventional parameters: absorbance at 420nm (A420) and the content of 5-hydroxymethyl-2-furfural (5-HMF). A high similarity of the spectral profiles for all sparkling wines analyzed was observed, being explained by a four component PARAFAC model. A high correlation between the third PARAFAC factor (465/530nm) and the commonly used non-enzymatic browning indicators was observed. The fourth PARAFAC factor (280/380nm) gives us also information about the browning process following a first order kinetic reaction. Hence, excitation-emission fluorescence spectroscopy, together with PARAFAC, provides a faster alternative for browning monitoring to conventional methods, as well as useful key indicators for quality control. PMID:27041327

  7. [Commercial orange juice beverages detection by fluorescence spectroscopy combined with PCA-ED and PLSR methods].

    Science.gov (United States)

    Hu, Yang-jun; Zhu, Chun; Chen, Guo-qing; Zhang, Yong; Kong, Fan-biao; Li, Run; Zhu, Zhuo-wei; Wang, Xu; Gao, Shu-mei

    2014-08-01

    In order to classify the orange juiice beverages effectively, the fluorescence character differences of two kinds of orange juice beverages including 100% orange juice and orange drink were analyzed and compared, principal component analysis combined with Euclidean distance was adopted to classify two kinds of orange juice beverages, and ideal classification results were obtained. Meanwhile, the orange juice content estimation model was established by using fluorescence spectroscopy combined with partial least squares regression method, and the correlation coefficient R, root mean square error of calibration RMSEC and root mean square error of prediction RMSEP were 0.997, 0.87% and 2.05%, respectively. The experimental results indicate that the calibration model offers comparatively accurate content estimation, which reflect the actual orange juice content in the commercial orange juice beverages. The exploration to classify orange juice beverages was carried out from two aspects of qualitative and quantitative analysis by employing fluorescence spectroscopy combined with chemometrics method, which can provide a new idea for the classification and adulteration detection of commercial orange juice beverages, and also can give certain reference basis for the quality control of orange juice raw material.

  8. Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy.

    Science.gov (United States)

    Yu, Xianyong; Liu, Ronghua; Yi, Rongqiong; Yang, Fengxian; Huang, Haowen; Chen, Jian; Ji, Danhong; Yang, Ying; Li, Xiaofang; Yi, Pinggui

    2011-04-01

    The fluorescence and ultraviolet spectroscopy were explored to study the interaction between N-confused porphyrins (NCP) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results indicated that the fluorescence quenching mechanism between BSA and NCP was static quenching procedure at low NCP concentration at 293 and 305 K or a combined quenching (static and dynamic) procedure at higher NCP concentration at 305 K. The binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. The comparison of binding potency of the three NCP to BSA showed that the substituting groups in benzene ring could enhance the binding affinity. From the thermodynamic parameters, we concluded that the action force was mainly hydrophobic interaction. The binding distances between NCP and BSA were calculated using Förster non-radiation energy transfer theory. In addition, the effect of NCP on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.

  9. Fourier transform infrared and fluorescence spectroscopy for analysis of vegetable oils

    Directory of Open Access Journals (Sweden)

    Nigri S.

    2013-09-01

    Full Text Available Fourier transform infrared (FTIR and fluorescence spectroscopy, combined with chemometric approaches have been developed to analysis of extra virgin olive oil adulterated with pomace olive oil. The measurements were made on pure vegetable oils: extra virgin oil, pomace olive oil and that adulterated with varying concentration of pomace olive oil. Today, the application of FTIR spectroscopy has increased in food studied, and particularly has become a powerful analytical tool in the study of edible oils and fats. The spectral regions where the variations were observed chosen for developing models and cross validation was used. The synchronous fluorescence spectrometry takes advantage of the hardware capability to vary both the excitation and emission wavelengths during the analysis with constant wavelength difference is maintained between the two. The region between 300 and 400 nm is attributed to the tocopherols and phenols, the derivatives of vitamin E are associated with the region 400–600 nm and the bands in the region of 600–700 nm are attributed to the chlorophyll and peophytin pigments. The results presented in this study suggest that FTIR and fluorescence may be a useful tool for analysis and detecting adulteration of extra virgin olive oil with pomace oil.

  10. Field-emission spectroscopy of beryllium atoms adsorbed on tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, J.J.; Grzesiak, W.; Krajniak, J. (Politechnika Wroclawska (Poland))

    1981-01-01

    Field emission energy distributions (FEED) have been measured for the beryllium-tungsten (023) adsorption system over the 78-450 K temperature range. A temperature dependence of the normalized half-width, ..delta../d, of FEED peaks changed significantly due to beryllium adsorption; and the curve, ..delta../d vs p, for the Be/W adsorption system was identical in character to the calculated curve based on the free electron model in contrast to the curve for the clean tungsten surface. In the last part of this paper Gadzuk's theory of the resonance-tunneling effect is applied to the beryllium atom on tungsten. Experimental and theoretical curves of the enhancement factor as a function of energy have been discussed.

  11. Resonant three-photon ionization spectroscopy of atomic Fe

    Science.gov (United States)

    Liu, Y.; Gottwald, T.; Havener, C. C.; Mattolat, C.; Vane, C. R.; Wendt, K.

    2013-12-01

    Laser spectroscopic investigations on high-lying states around the ionization potential (IP) in the atomic spectrum of Fe have been carried out for the development of a practical three-step resonance ionization scheme accessible by Ti: sapphire lasers. A hot cavity laser ion source, typically used at on-line radioactive ion beam production facilities, was employed in this work. Ionization schemes employing high-lying Rydberg and autoionizing states populated by three-photon excitations were established. Five new Rydberg and autoionizing Rydberg series converging to the ground and to the first four excited states of Fe II are reported. Analyses of the Rydberg series yield the value 63 737.686 ± 0.068 cm-1 for the ionization potential of iron.

  12. Ionization potential of neutral atomic plutonium determined by laser spectroscopy

    International Nuclear Information System (INIS)

    The ionization potential of the neutral plutonium atom, Pu i, has been determined by two- and three-step resonance photoionization observation of the threshold of ionization and of the Rydberg series. The Rydberg series were observed by field ionization as series that converge to the first ionization limit and as autoionizing series the converge to the second and to several higher convergence limits. The threshold and Rydberg series were obtained through a number of two- and three-step pathways. The photoionization threshold value for the 239Pu i ionization potential is 48 582(30) cm-1, and the more accurate value from the Rydberg series is 48 604(1) cm-1 or 6.0262(1) eV

  13. Resonant three-photon ionization spectroscopy of atomic Fe

    International Nuclear Information System (INIS)

    Laser spectroscopic investigations on high-lying states around the ionization potential (IP) in the atomic spectrum of Fe have been carried out for the development of a practical three-step resonance ionization scheme accessible by Ti: sapphire lasers. A hot cavity laser ion source, typically used at on-line radioactive ion beam production facilities, was employed in this work. Ionization schemes employing high-lying Rydberg and autoionizing states populated by three-photon excitations were established. Five new Rydberg and autoionizing Rydberg series converging to the ground and to the first four excited states of Fe II are reported. Analyses of the Rydberg series yield the value 63 737.686 ± 0.068 cm−1 for the ionization potential of iron. (paper)

  14. Resonant three-Photon Ionization Spectroscopy of Atomic Fe

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuan [ORNL; Gottwald, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Havener, Charles C [ORNL; Mattolat, C. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Vane, C Randy [ORNL; Wendt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany

    2013-01-01

    Laser spectroscopic investigations on high-lying states around the ionization potential in the atomic spectrum of Fe have been carried out for development of a practical three-step resonance ionization scheme accessible by Ti:Sapphire lasers. A hot cavity laser ion source typically used at on-line radioactive ion beam production facilities was employed in this work. Ionization schemes employing high-lying Rydberg and autoionizing states populated by three-photon excitations were established. Five new Rydberg and autoionizing Rydberg series converging to the ground and to the first four excited states of Fe II are reported. Analyses of the Rydberg series yield the value 63737.686 0.068 cm-1 for the ionization potential of iron.

  15. An atomic hydrogen beam to test ASACUSA’s apparatus for antihydrogen spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diermaier, M., E-mail: martin.diermaier@oeaw.ac.at; Caradonna, P.; Kolbinger, B. [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria); Malbrunot, C. [CERN (Switzerland); Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Wolf, M.; Zmeskal, J.; Widmann, E. [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria)

    2015-08-15

    The ASACUSA collaboration aims to measure the ground state hyperfine splitting (GS-HFS) of antihydrogen, the antimatter counterpart to atomic hydrogen. Comparisons of the corresponding transitions in those two systems will provide sensitive tests of the CPT symmetry, the combination of the three discrete symmetries charge conjugation, parity, and time reversal. For offline tests of the GS-HFS spectroscopy apparatus we constructed a source of cold polarised atomic hydrogen. In these proceedings we report the successful observation of the hyperfine structure transitions of atomic hydrogen with our apparatus in the earth’s magnetic field.

  16. Histologic differences between orthotopic xenograft pancreas models affect Verteporfin uptake measured by fluorescence microscopy and spectroscopy

    Science.gov (United States)

    O'Hara, Julia A.; Samkoe, Kimberley S.; Chen, Alina; Isabelle, Martin; Hoopes, P. J.; Hasan, Tayyaba; Pogue, Brian W.

    2012-02-01

    Photodynamic therapy (PDT) that uses the second generation photosensitizer, verteporfin (VP), is a developing therapy for pancreatic cancer. The optimal timing of light delivery related to VP uptake and distribution in pancreatic tumors will be important information to obtain to improve treatment for this intractable disease. In this work we examined uptake and distribution of VP in two orthotopic pancreatic tumors with different histological structure. ASPC-1 (fast-growing) and Panc-1 (slower growing) tumors were implanted in SCID mice and studied when tumors were approximately 100mm3. In a pilot study, these tumors had been shown to differ in uptake of VP using lightinduced fluorescence spectroscopy (LIFS) in vivo and fluorescence imaging ex vivo and that work is extended here. In vivo fluorescence mean readings of tumor and liver increased rapidly up to 15 minutes after photosensitizer injection for both tumor types, and then continued to increase up to 60 minutes post injection to a higher level in ASPC-1 than in Panc-1. There was variability among animals with the same tumor type, in both liver and tumor uptake and no selectivity of tumor over liver. In this work we further examined VP uptake at multiple time points in relation to microvascular density and perfusion, using DiOC7 (to mark blood vessels) and VP fluorescence in the same tissue slices. Analysis of DiOC7 fluorescence indicates that AsPC-1 and Panc-1 have different vascular densities but AsPC-1 vasculature is more perfusive. Analysis of colocalized DiOC7 and VP fluorescence showed ASPC-1 with higher accumulation of VP 3 hrs after injection and more VP at a distance from blood vessels compared to Panc-1. This work shows the need for techniques to analyze photosensitizer distribution in order to optimize photodynamic therapy as an effective treatment for pancreatic tumors.

  17. Investigation of the inclusion behavior between p-sulfoniccalix[8]arene and norfloxacin by fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The host-guest complexation between p-sulfoniccalix[8]arene (SC8A) and norfloxacin (NFLX) in aqueous solution was investigated by fluorescence spectroscopy. Strong fluorescence intensity of the NFLX aqueous solution alone and obvious fluorescence quenching of NFLX solution in the presence of SC8A were observed. The fluorescence lifetimes of NFLX and SC8A-NFLX inclusion complex were determined and the effect of temperature on SC8A-NFLX inclusion complex was studied. The static quenching of the inclusion was obtained, that is the SC8A can form a nonfluorescent ground-state inclusion complex with NFLX. As the results show, the combined ratio (n) was 1:1 and association constant K was 1.17x105 L/mol. Based on the experimental results, the mechanism of the inclusion complex was explored. The space matching, electrostatic force and hydrogen bond play important effects in the inclusion process. Subsequently, the addition of bovine serum albumin (BSA) solution led to the recovery of fluorescence intensity. It is indicated that BSA can liberate the NFLX into the solution by destructing the SC8A-NFLX inclusion complex. Hence SC8A may be used for controlled-release drug delivery in the pharmaceutical industry. - Highlights: → Fluorescence lifetimes of NFLX and SC8A-NFLX inclusion complex were determined. → Mechanism of the SC8A-NFLX inclusion complex was explored. → It is proved that SC8A can form a nonfluorescent ground-state inclusion complex with NFLX.

  18. Development of atomic spectroscopy methods in geological institutes of Faculty of Natural Sciences Comenius University and Slovak Academy of Science

    International Nuclear Information System (INIS)

    Development of atomic spectrochemistry methods in Geological Institute of Faculty of Natural Sciences, Comenius University (GI FNS CU) is connected with its establishment in 1957. Its instrumental equipment and location resulted from the already existing Laboratory in the Chair for Mineralogy and Crystallography of FNS CU. In Geological Institute of Slovak Academy of Science (GI SAS) the development of atomic spectroscopy methods started later, only since 1963, when the Member of Academy, Prof. RNDr. B. Cambel, DrSc. became its director. In both institutes the methods of atomic emission spectrography were used as first. A new quality in the development started since 1969 when the Institutes moved to common buildings in Petrzalka (Bratislava), the first atomic absorption spectrometers were acquired and the Institutes were 'strengthened' by coming of Prof. Ing. E. Plsko, DrSc. In the following years the Institutes started to collaborate with some other organisations which were equipped with new facilities, e.g. in 1975 with X-ray fluorescence spectrometer, electron microprobe and in 1985 with inductively coupled plasma atomic emission spectrometer. This enabled to improve essentially the quality of research activities of both institutes in the chemical characterisation of geological materials, as well as in pedagogical work (students practice, diploma works and dissertations). In the present time characterized by new economic conditions a reduction of GI SAS laboratory activities has been realised. The laboratories of the GI FNS CU have, thanks to their director Ing. V. Stresko, PhD. shown also hence-forward a rich research, pedagogical and society activities what can be documented by numerous publications, citations, obtained awards, representations in professional societies and commissions, local and foreign advisory boards, accreditation boards etc. (author)

  19. Probe pressure effects on human skin diffuse reflectance and fluorescence spectroscopy measurements.

    Science.gov (United States)

    Lim, Liang; Nichols, Brandon; Rajaram, Narasimhan; Tunnell, James W

    2011-01-01

    Diffuse reflectance and fluorescence spectroscopy are popular research techniques for noninvasive disease diagnostics. Most systems include an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. The purpose of this study is to investigate probe pressure effects on human skin spectroscopic measurements. We conduct an in-vivo experiment on human skin tissue to study the short-term (30 s) effects of probe pressure on diffuse reflectance and fluorescence measurements. Short-term light probe pressure (P0<9 mN∕mm2) effects are within 0 ± 10% on all physiological properties extracted from diffuse reflectance and fluorescence measurements, and less than 0±5% for diagnostically significant physiological properties. Absorption decreases with site-specific variations due to blood being compressed out of the sampled volume. Reduced scattering coefficient variation is site specific. Intrinsic fluorescence shows a large standard error, although no specific pressure-related trend is observed. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Therefore, the effects of pressure can be minimized when the pressure is small and applied for a short amount of time; however, long-term and large pressures induce significant distortions in measured spectra. PMID:21280899

  20. Inductively coupled plasma-atomic emission spectroscopy: The determination of trace impurities in uranium hexafluoride

    Science.gov (United States)

    Floyd, M. A.; Morrow, R. W.; Farrar, R. B.

    An analytical method has been developed for the determination of trace impurities in high-purity uranium hexafluoride using liquid-liquid extraction of the uranium from the trace impurities followed by analysis with inductively coupled plasma-atomic emission spectroscopy. Detection limits, accuracy, and precision data are presented.

  1. Circuit Board Analysis for Lead by Atomic Absorption Spectroscopy in a Course for Nonscience Majors

    Science.gov (United States)

    Weidenhammer, Jeffrey D.

    2007-01-01

    A circuit board analysis of the atomic absorption spectroscopy, which is used to measure lead content in a course for nonscience majors, is being presented. The experiment can also be used to explain the potential environmental hazards of unsafe disposal of various used electronic equipments.

  2. Temperature imaging of turbulent dilute spray flames using two-line atomic fluorescence

    Science.gov (United States)

    Medwell, Paul R.; Masri, Assaad R.; Pham, Phuong X.; Dally, Bassam B.; Nathan, Graham J.

    2014-11-01

    This paper reports the first application of nonlinear excitation regime two-line atomic fluorescence imaging (NTLAF) of indium to measure temperature in turbulent flames of dilute sprays. Indium chloride is dissolved in acetone fuel which is atomised with an ultrasonic nebuliser and supplied with carrier air into a standard piloted burner. It is found that the indium fluorescence signal is not affected by scattering from the droplets or fuel vapour and that no changes to the optical arrangement used with gaseous flames were required. Notwithstanding the lower temperature thresholds of 800 K imposed by the population of excitation species for the NTLAF method and of 1,200 K imposed by the mechanism of releasing gas-phase indium from its salt, the comparisons of conditional and pseudo-unconditional means with thermocouple measurements performed in a range of turbulent spray flames are quite favourable. The NTLAF signal quality deteriorates on the jet centreline at upstream locations and on the lean side of the flame, the former being largely due to insufficient conversion of indium chloride to indium atoms and the latter potentially due to indium oxidation. Nevertheless, the signal-to-noise ratios obtained in the reaction zone regions are good and the results reveal the expected temperature trends in the turbulent spray flames tested here. Further developments are necessary to resolve the mechanism of indium formation and to broaden the temperature range.

  3. Interactions between fluorescence of atomically layered graphene oxide and metallic nanoparticles

    Science.gov (United States)

    Wang, Yu; Li, Shao-Sian; Yeh, Yun-Chieh; Yu, Chen-Chieh; Chen, Hsuen-Li; Li, Feng-Chieh; Chang, Yu-Ming; Chen, Chun-Wei

    2013-01-01

    Graphene oxide (GO) demonstrates interesting photoluminescence (PL) because of its unique heterogeneous atomic structure, which consists of variable sp2- and sp3-bonded carbons. In this study, we report the interaction between the luminescence of GO ranging from a single atomic layer to few-layered thin films and localized surface plasmon resonance (LSPR) from silver nanoparticles (Ag NPs). The photoluminescence of GO in the vicinity of the Ag NPs is enhanced significantly due to the near-field plasmonic effect by coupling electron-hole pairs of GO with oscillating electrons in Ag NPs, leading to an increased PL intensity and a decreased PL decay lifetime. The maxima 30-fold enhancement in PL intensity is obtained with an optimized film thickness of GO, and the luminescence image from a single atomic layer GO sheet is successfully observed with the assistance of the LSPR effect. The results provide an ideal platform for exploring the interactions between the fluorescence of two-dimensional layered materials and the LSPR effect.Graphene oxide (GO) demonstrates interesting photoluminescence (PL) because of its unique heterogeneous atomic structure, which consists of variable sp2- and sp3-bonded carbons. In this study, we report the interaction between the luminescence of GO ranging from a single atomic layer to few-layered thin films and localized surface plasmon resonance (LSPR) from silver nanoparticles (Ag NPs). The photoluminescence of GO in the vicinity of the Ag NPs is enhanced significantly due to the near-field plasmonic effect by coupling electron-hole pairs of GO with oscillating electrons in Ag NPs, leading to an increased PL intensity and a decreased PL decay lifetime. The maxima 30-fold enhancement in PL intensity is obtained with an optimized film thickness of GO, and the luminescence image from a single atomic layer GO sheet is successfully observed with the assistance of the LSPR effect. The results provide an ideal platform for exploring the

  4. Measurement of the temperature-dependent diffusion properties of nanoparticles by using fluorescence correlation spectroscopy

    Science.gov (United States)

    Jung, Chanbae; Lee, Jaeran; Kang, Manil; Kim, Sok Won

    2014-10-01

    Changes in the diffusion properties of three kinds of fluorescent particles, Alexa Fluor 647, Q-dots (quantum dots), and beads, with temperature were investigated with a home-built fluorescence correlation spectroscopy (FCS) system based on a confocal microscope. In all samples, as the temperature was increased, the diffusion times were reduced, indicating an increase in the diffusion coefficient. In particular, of all the particles, Alexa Fluor 647 having the smallest size of ˜1 nm, showed a hydrodynamic radius that increased with increasing temperature of the solvent. However, for the Q-dots and beads with larger sizes, the hydrodynamic radius of the particles was inversely proportional to the temperature. These results show that diffusion coefficient obtained by changing the temperature has an influence on the hydrodynamic radius of the particles.

  5. Measurement of the temperature-dependent diffusion properties of nanoparticles by using fluorescence correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chanbae; Lee, Jaeran; Kang, Manil; Kim, Sokwon [University of Ulsan, Ulsan (Korea, Republic of)

    2014-10-15

    Changes in the diffusion properties of three kinds of fluorescent particles, Alexa Fluor 647, Q-dots (quantum dots), and beads, with temperature were investigated with a home-built fluorescence correlation spectroscopy (FCS) system based on a confocal microscope. In all samples, as the temperature was increased, the diffusion times were reduced, indicating an increase in the diffusion coefficient. In particular, of all the particles, Alexa Fluor 647 having the smallest size of ∼1 nm, showed a hydrodynamic radius that increased with increasing temperature of the solvent. However, for the Q-dots and beads with larger sizes, the hydrodynamic radius of the particles was inversely proportional to the temperature. These results show that diffusion coefficient obtained by changing the temperature has an influence on the hydrodynamic radius of the particles.

  6. What information is contained in the fluorescence correlation spectroscopy curves, and where

    Science.gov (United States)

    Khadem, S. M. J.; Hille, C.; Löhmannsröben, H.-G.; Sokolov, I. M.

    2016-08-01

    We discuss the application of fluorescence correlation spectroscopy (FCS) for characterization of anomalous diffusion of tracer particles in crowded environments. While the fact of anomaly may be detected by the standard fitting procedure, the value of the exponent α of anomalous diffusion may be not reproduced correctly for non-Gaussian anomalous diffusion processes. The important information is however contained in the asymptotic behavior of the fluorescence autocorrelation function at long and at short times. Thus, analysis of the short-time behavior gives reliable values of α and of lower moments of the distribution of particles' displacement, which allows us to confirm or reject its Gaussian nature. The method proposed was tested on the FCS data obtained in artificial crowded fluids and in living cells.

  7. Structure and dynamics of fluorescently labeled complex fluids by fourier imaging correlation spectroscopy

    Science.gov (United States)

    Grassman; Knowles; Marcus

    2000-12-01

    We present a method of Fourier imaging correlation spectroscopy (FICS) that performs phase-sensitive measurements of modulated optical signals from fluorescently labeled complex fluids. FICS experiments probe the time-dependent trajectory of a spatial Fourier component of the fluid particle density at a specified wave number k, and provide a direct route to the intermediate scattering function. The FICS approach overcomes signal sensitivity problems associated with dynamic light scattering, while offering a means to acquire time-dependent information about spatial distributions of fluorescent particles, superior in efficiency to direct imaging methods. We describe the instrumental setup necessary to perform FICS experiments, and outline the theory that establishes the connection between FICS observables and statistical mechanical quantities describing liquid state dynamics. Test measurements on monolayer suspensions of rhodamine labeled polystyrene spheres are detailed.

  8. Application of X-ray Fluorescence Spectroscopy in Analysis of Oil Paint Pigments

    Science.gov (United States)

    Major, Cassandra; Formica, Sarah

    2011-10-01

    X-ray Fluorescence (XRF) spectroscopy is a rapid, noninvasive technique for both detecting and identifying chemical elements within a given sample. At North Georgia College and State University, a sealed tube x-ray source and slightly focusing polycapillary optic are used in nondestructive XRF analysis of oil paint pigments. Oil paints contain both organic and inorganic matter, and the inorganic ingredients such as titanium, vanadium, iron, zinc, and other elements are easily detected by XRF, which can be used to uniquely differentiate between various paint pigments. To calibrate the XRF system for paint color identification, six different colors of oil paint were fluoresced and identified based off of their characteristic spectra. By scanning the paint sample in two dimensions, the characteristic XRF spectra obtained were compiled to produce an XRF replica of the painting.

  9. Continuation of Atomic Spectroscopy on Alkali Isotopes at ISOLDE

    CERN Multimedia

    2002-01-01

    Laser optical measurements on Rb, Cs and Fr have already been performed at ISOLDE in 1978-79. The hyperfine structure and isotope shift of |7|6|-|9|8Rb, |1|1|8|-|1|4|5Cs, |2|0|8|-|2|1|3Fr and 14 of their isomers have been studied. Among the wealth of information which has been obtained, the most important are the first observation of an optical transition of the element Fr, the evidence of the onset of nuclear deformation at N~=~60 for Rb isotopes and the shape isomerism isotopes. \\\\ \\\\ From both the atomic and nuclear physics point of view, new studies seem very promising: \\item - the search for new optical transitions in Fr; the shell effect in the rms charge radius at N~=~126 for Fr isotopes \\item - the study of a possible onset of deformation for Cs isotopes beyond |1|4|5Cs \\item - the study of a region of static deformation in neutron-deficient Rb isotopes. \\\\ \\\\ \\end{enumerate} A new apparatus has been built. The principle remains the same as used in our earlier experiments. The improvements concern ess...

  10. Theoretical Studies on Electronic Structures and Spectroscopy of Fluorescent Arylamino Fumaronitrile

    Institute of Scientific and Technical Information of China (English)

    Xiao-peng Chen; Yu-qi Ding; Qi-wen Teng

    2008-01-01

    A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G* level.Based on the optimized geometries,the electronic,fluorescent and 13C NMR spectra are calculated with INDO/CIS,CIS-ZINDO TD,and B3LYP/6-31G* methods,re-spectively.Starting with the first of the series,the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra axe blue-shifted owing to the large steric effect of naphthyl rings.On the contrary,the energy gaps of the derivatives turn narrow,and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system.The chemical shifts of sp2-C on the phenyl rings are moved upfield,while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups.

  11. Fluorescence spectroscopy as a tool for quality assessment of humic substances

    Science.gov (United States)

    Boguta, Patrycja

    2016-04-01

    *The studies were partly carried out within the framework of a research project. The project was financed from funds of National Science Center on the base of decision number DEC-2013/11/D/NZ9/02545. Fluorescence spectroscopy belongs to modern, non-destructive, rapid and relatively cheap methods, as well as for many years it was successfully used in studies of organic compounds in the fields of medicine, biology and chemistry. On the other hand, soil organic matter is a group of compounds with a complex spatial structure showing a large number of groups with different kinds of fluorophores. This could suggest the possibility of application of fluorescence spectroscopy in assessing the quality of humic substances as well as in monitoring of their chemical transformations. The aim of study was chemical description of humic and fulvic acids based on fluorescence spectra, as well as an attempt of evaluation of changes occurring under the influence of different pH and during interactions with various concentrations of metal. The humic and fulvic acids were isolated from chemically different soils. The measurements were carried out on Hitachi fluorescence spectrometer in solutions with a concentration of humic acids 40mg dm-3, at pH from 3 to 7, and for the evaluation of the metal impact: with increasing Zn concentrations (0-50mg dm-3). The fluorescence spectra were recorded in the form of synchronous and emission-excitation matrices (EEM). Studies have shown the presence of different groups of fluorophores. Synchronous spectra were characterized by a well-separated bands showing fluorescence in the area of low, medium and high wavelengths, suggesting the presence of structures, both weakly and strongly humified. EEM spectra revealed map of fluorophores within wide ranges of emission and excitation. Fluorophores differed in both position and intensity. The highest intensity was observed for compounds with the lowest humification degree which might be due to high amount

  12. Direct Vpr-Vpr Interaction in Cells monitored by two Photon Fluorescence Correlation Spectroscopy and Fluorescence Lifetime Imaging

    Directory of Open Access Journals (Sweden)

    Mély Yves

    2008-09-01

    Full Text Available Abstract Background The human immunodeficiency virus type 1 (HIV-1 encodes several regulatory proteins, notably Vpr which influences the survival of the infected cells by causing a G2/M arrest and apoptosis. Such an important role of Vpr in HIV-1 disease progression has fuelled a large number of studies, from its 3D structure to the characterization of specific cellular partners. However, no direct imaging and quantification of Vpr-Vpr interaction in living cells has yet been reported. To address this issue, eGFP- and mCherry proteins were tagged by Vpr, expressed in HeLa cells and their interaction was studied by two photon fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy. Results Results show that Vpr forms homo-oligomers at or close to the nuclear envelope. Moreover, Vpr dimers and trimers were found in the cytoplasm and in the nucleus. Point mutations in the three α helices of Vpr drastically impaired Vpr oligomerization and localization at the nuclear envelope while point mutations outside the helical regions had no effect. Theoretical structures of Vpr mutants reveal that mutations within the α-helices could perturb the leucine zipper like motifs. The ΔQ44 mutation has the most drastic effect since it likely disrupts the second helix. Finally, all Vpr point mutants caused cell apoptosis suggesting that Vpr-mediated apoptosis functions independently from Vpr oligomerization. Conclusion We report that Vpr oligomerization in HeLa cells relies on the hydrophobic core formed by the three α helices. This oligomerization is required for Vpr localization at the nuclear envelope but not for Vpr-mediated apoptosis.

  13. Sample preparation of waste water to determine metallic contaminants by X-ray fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Trace X-ray fluorescence spectroscopy analysis in liquid samples is preceded by sample preparation, which usually consists in the precipitation of the metallic ions and concentration over a thin cellulose filter. The samples preparation of waste water by this method is not efficient, due to the great amount of organic and insoluble matter that they contain. The purpose of this work was to determine the optimal value of pH in order to adsorbe all the insoluble matter contained in a waste water sample in the activated charcoal, so that the metallic ions could be precipitated and concentrated on a thin filter and determinated by X-ray fluorescence spectroscopy. A survey about the adsorption of some ions in activated charcoal in function of the pH was made for the following: Cr3+, Fe3+, Ni2+, Cu2+, Zn2+, Se2+, Hg2+, and Pb2+. It was observed that at pH 0, the ions are not adsorbed, but Cu2+ and Zn2+ are adsorbed in small amount; at pH 14, the ions are adsorbed, excluding Se, which is not adsorbed at any value of pH. If a waste water sample is treated at pH 0 with activated charcoal to adsorbe the organic and insoluble matter, most of the metallic ions are not adsorbed by the activated charcoal and could be precipitated with APDC (ammonium 1-pirrolidine dithio carbamate salt) and concentrated on a thin filter. The analysis of the metallic ions contained on the filter and those adsorbed in the activated charcoal by X-ray fluorescence spectroscopy, gave the total amount of the ions in the sample. (author)

  14. Development of a 2D temperature measurement technique for combustion diagnostics using 2-line atomic fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Engstroem, Johan

    2001-01-01

    The present thesis is concerned with the development and application of a novel planar laser-induced fluorescence (PLIF) technique for temperature measurements in a variety of combusting flows. Accurate measurement of temperature is an essential task in combustion diagnostics, since temperature is one of the most fundamental quantities for the characterization of combustion processes. The technique is based on two-line atomic fluorescence (TLAF) from small quantities of atomic indium (In) seeded into the fuel. It has been developed from small-scale experiments in laboratory flames to the point where practical combustion systems can be studied. The technique is conceptually simple and reveals temperature information in the post-flame regions. The viability of the technique has been tested in three extreme measurement situations: in spark ignition engine combustion, in ultra-lean combustion situations such as lean burning aero-engine concepts and, finally, in fuel-rich combustion. TLAF was successfully applied in an optical Sl engine using isooctane as fuel. The wide temperature sensitivity, 700 - 3000 K, of the technique using indium atoms allowed measurements over the entire combustion cycle in the engine to be performed. In applications in lean combustion a potential problem caused by the strong oxidation processes of indium atoms was encountered. This limits measurement times due to deposits of absorbing indium oxide on measurement windows. The seeding requirement is a disadvantage of the technique and can be a limitation in some applications. The results from experiments performed in sooting flames are very promising for thermometry measurements in such environments. Absorption by hydrocarbons and other native species was found to be negligible. Since low laser energies and low seeding concentrations could be used, the technique did not, unlike most other incoherent optical thermometry techniques, suffer interferences from LII of soot particles or LIF from PAH

  15. Simulation and Characterization of Single Photon Detectors for Fluorescence Lifetime Spectroscopy and Gamma-ray Applications

    OpenAIRE

    Benetti, Michele

    2012-01-01

    Gamma-ray and Fluorescence Lifetime Spectroscopies are driving the development of non-imaging silicon photon sensors and, in this context, Silicon Photo-Multipliers (SiPM)s are leading the starring role. They are 2D array of optical diodes called Single Photon Avalanche Diodes (SPAD)s, and are normally fabricated with a dedicated silicon process. SPADs amplify the charge produced by the single absorbed photon in a way that recalls the avalanche amplification exploited in Photo-Multiplier Tube...

  16. Effect of different agents onto multidrug resistant cells revealed by fluorescence correlation spectroscopy

    Science.gov (United States)

    Boutin, C.; Roche, Y.; Jaffiol, R.; Millot, J.-M.; Millot, C.; Plain, J.; Deturche, R.; Jeannesson, P.; Manfait, M.; Royer, P.

    Fluorescence correlation spectroscopy (FCS), which is a sensitive and non invasive technique, has been used to characterize the plasma membrane fluidity and heterogeneity of multidrug resistant living cells. At the single cell level, the effects of different membrane agents present in the extra-cellular medium have been analyzed. Firstly, we reveal a modification of plasma membrane microviscosity according to the addition of a fluidity modulator, benzyl alcohol. In the other hand, revertant such as verapamil and cyclosporin-A appears to act more specifically on the slow diffusion sites as microdomains.

  17. Study on the interaction of anticancer drug mitoxantrone with DNA by fluorescence and Raman spectroscopies

    Institute of Scientific and Technical Information of China (English)

    Lingjuan Tang; Zhenrong Sun; Jianyu Guo; Zugeng Wang

    2006-01-01

    @@ Mitoxantrone, a clinically useful antitumour antibiotic for leukaemia and breast cancer, has received more attentions. In this paper, the interaction between mitoxantrone and calf thymus DNA is investigated by Raman and fluorescence spectroscopies, and the binding site of mitoxantrone to calf thymus DNA is explored. The results showed that mitoxantrone interacts with calf thymus DNA bases by the intercalation of anthracycline into the base pair plane of adenine (A) and thymine (T), and it results in the disruption of the hydrogen bonds between calf thymus DNA bases, and thus the calf thymus DNA double-strand can be disrupted into the B-form DNA double-strand segments.

  18. Host-Guest Complexation Studied by Fluorescence Correlation Spectroscopy: Adamantane–Cyclodextrin Inclusion

    OpenAIRE

    Wajih Al-Soufi; Mercedes Novo; Maria Jesus Pérez-Alvite; Jorge Bordello; Daniel Granadero

    2010-01-01

    The host-guest complexation between an Alexa 488 labelled adamantane derivative and β-cyclodextrin is studied by Fluorescence Correlation Spectroscopy (FCS). A 1:1 complex stoichiometry and a high association equilibrium constant of K = 5.2 × 104 M-1 are obtained in aqueous solution at 25 °C and pH = 6. The necessary experimental conditions are discussed. FCS proves to be an excellent method for the determination of stoichiometry and association equilibrium constant of this type of complexes,...

  19. Detection of orange juice frauds using front-face fluorescence spectroscopy and Independent Components Analysis.

    Science.gov (United States)

    Ammari, Faten; Redjdal, Lamia; Rutledge, Douglas N

    2015-02-01

    The aim of this study was to find simple objective analytical methods to assess the adulteration of orange juice by grapefruit juice. The adulterations by addition of grapefruit juice were studied by 3D-front-face fluorescence spectroscopy followed by Independent Components Analysis (ICA) and by classical methods such as free radical scavenging activity and total flavonoid content. The results of this study clearly indicate that frauds by adding grapefruit juice to orange juice can be detected at percentages as low as 1%.

  20. Study of vitamin A distribution in rats by laser induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    We applied the laser induced fluorescence spectroscopy (LIFS) to investigate intestinal and liver tissues of normal male Wistar rats fed with vitamin A. The special procedure based on intensity spectral functions fitting was developed for the recognition of vitamin A in different tissues. Based on this procedure it is demonstrated that the LIFS can be used to monitor vitamin A deposition and distribution in the body of rat, which is essential for understanding the mechanism of formation of the vitamin A rich droplets, as the mechanism of vitamin A mobilization

  1. Recent Developments in Fluorescence Correlation Spectroscopy for Diffusion Measurements in Planar Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Martin Hof

    2010-01-01

    Full Text Available Fluorescence correlation spectroscopy (FCS is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support.

  2. European Group for Atomic Spectroscopy. Summaries of contributions, eleventh annual conference, Paris-Orsay, July 10-13, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    Summaries are presented of talks given at the eleventh conference of the European group for atomic spectroscopy. Topics covered include: lifetimes; collisions; line shape; hyperfine structure; isotope shifts; saturation spectroscopy; Hanle effect; Rydberg levels; quantum beats; helium and helium-like atoms; metrology; and molecules. (GHT)

  3. Tissue diagnosis using power-sharing multifocal Raman micro-spectroscopy and auto-fluorescence imaging

    Science.gov (United States)

    Sinjab, Faris; Kong, Kenny; Gibson, Graham; Varma, Sandeep; Williams, Hywel; Padgett, Miles; Notingher, Ioan

    2016-01-01

    We describe a multifocal Raman micro-spectroscopy detection method based on a digital micromirror device, which allows for simultaneous “power-sharing” acquisition of Raman spectra from ad hoc sampling points. As the locations of the points can be rapidly updated in real-time via software control of a liquid-crystal spatial light modulator (LC-SLM), this technique is compatible with automated adaptive- and selective-sampling Raman spectroscopy techniques, the latter of which has previously been demonstrated for fast diagnosis of skin cancer tissue resections. We describe the performance of this instrument and show examples of multiplexed measurements on a range of test samples. Following this, we show the feasibility of reducing measurement time for power-shared multifocal Raman measurements combined with confocal auto-fluorescence imaging to provide guided diagnosis of tumours in human skin samples. PMID:27570692

  4. Determination of methyl mercury by aqueous phase Eehylation, followed by gas chromatographic separation with cold vapor atomic fluorescence detection

    Science.gov (United States)

    De Wild, John F.; Olsen, Mark L.; Olund, Shane D.

    2002-01-01

    A recent national sampling of streams in the United States revealed low methyl mercury concentrations in surface waters. The resulting median and mean concentrations, calculated from 104 samples, were 0.06 nanograms per liter (ng/L) and 0.15 ng/L, respectively. This level of methyl mercury in surface water in the United States has created a need for analytical techniques capable of detecting sub-nanogram per liter concentrations. In an attempt to create a U.S. Geological Survey approved method, the Wisconsin District Mercury Laboratory has adapted a distillation/ethylation/ gas-phase separation method with cold vapor atomic fluorescence spectroscopy detection for the determination of methyl mercury in filtered and unfiltered waters. This method is described in this report. Based on multiple analyses of surface water and ground-water samples, a method detection limit of 0.04 ng/L was established. Precision and accuracy were evaluated for the method using both spiked and unspiked ground-water and surface-water samples. The percent relative standard deviations ranged from 10.2 to 15.6 for all analyses at all concentrations. Average recoveries obtained for the spiked matrices ranged from 88.8 to 117 percent. The precision and accuracy ranges are within the acceptable method-performance limits. Considering the demonstrated detection limit, precision, and accuracy, the method is an effective means to quantify methyl mercury in waters at or below environmentally relevant concentrations

  5. Development of ultrasensitive spectroscopic analysis technology -Development of atomic spectroscopy technology-

    International Nuclear Information System (INIS)

    In this project, three principal techniques are developed. The laser photoionization spectrometry (LAPIS) is used for the ultrasensitive detection for heavy metals such as Pb and Cd. The Laser atomic fluorescence spectrometry is applied to the quantitative analysis of the lanthanide and actinide elements. And the DIAL remote sensing system is used for monitoring the ozone concentration and the atmospheric pollution. A time-of-flight mass spectrometer and a high efficient atomic beam generator were designed and manufactured. Various spectroscopic parameters and optimum analytical condition were investigated. By using the laser fluorescence technique, U, Eu and Sm in solution were quantitatively analyzed. The basic researches for the direct analytical method of solid samples were also carried out. The DIAL system for ozone remote sensing was developed and ozone concentration above Taejon were obtained. (Author)

  6. Development of atomic spectroscopy technologies - Hyperfine structure of 2 period atoms using optogalvanic effects

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Nam Ic [Hankuk University of foreign studies, Seoul (Korea)

    2000-03-01

    The source of anomalous broad linewidth of 3{sup 3}P{sub 1},{sub 2},{sub 3}-3{sup 3}D{sub 2},{sub 3},4(3s') transition was explained. The broad optogalvanic spectrum was consisted of two gaussian peaks of different linewidths, and they are separated by 250 MHz. The Narrow peak, which has linewidth of room temperature, is from oxygen atoms already separated, and the shifted broad peak, which has linewidth corresponding to a temperature of 9000 K, is from weakly bound molecular ions. Obtained hyperfine spectrum of fluorine atom at the expected frequency, was too weak to analyze hyperfine structure constants. Microwave discharge might be necessary for higher density of excited state. 16 refs., 11 figs. (Author)

  7. Real-Time Near-Field Terahertz Imaging with Atomic Optical Fluorescence

    CERN Document Server

    Wade, Christopher G; de Melo, Natalia R; Kondo, Jorge M; Adams, Charles S; Weatherill, Kevin J

    2016-01-01

    Terahertz (THz) near-field imaging is a flourishing discipline [1], with applications from fundamental studies of beam propagation [2,3] to the characterisation of metameterials [4,5] and waveguides [6,7]. Beating the diffraction limit typically involves rastering structures or detectors with length scale shorter than the radiation wavelength; in the THz domain this has been achieved using a number of techniques including scattering tips [8,9] and apertures [10]. Alternatively, mapping THz fields onto an optical wavelength and imaging the visible light removes the requirement for scanning a local probe, speeding up image collection times [11,12]. Here we report THz to optical conversion using a gas of highly excited `Rydberg' atoms. By collecting THz-induced optical fluorescence we demonstrate a real-time image of a THz standing wave and we use well-known atomic properties to calibrate the THz field strength. The mono-atomic gas does not distort the THz field and offers the potential to immerse structures wit...

  8. A rapid and noninvasive method to detect dried saliva stains from human skin using fluorescent spectroscopy

    Directory of Open Access Journals (Sweden)

    Kanwar Deep Singh Nanda

    2011-01-01

    Full Text Available Objective: Saliva is one of the vital fluids secreted in human beings. Significant amount of saliva is deposited on the skin during biting, sucking or licking, and can act as an important source in forensic evidence. An enzyme, α amylase, gives a characteristic emission spectrum at 345-355 nm when excited at 282 nm and this can be identified by using fluorescent spectroscopy and can help in forensic identification. This study describes a rapid method to detect dried saliva on the human skin by fluorescent spectroscopy. Materials and Methods: This study included 10 volunteers, who deposited their own saliva on skin of their ventral forearm by licking and water on the contralateral arm as control. This study was carried out at Central Leather Research Institute, Chennai. Study design: Ten volunteers deposited their own saliva on skin of their ventral forearm by licking. A control sample of water was deposited at the contralateral arm. Each sample was excited at 282 nm and emission spectrum was recorded. Results: The emission spectra of 10 swab samples taken from dried saliva were characterized at the primary peak of 345 to 355 nm whereas the emission spectrum of water as a control was recorded at 362 nm. Conclusion: The presence of emission spectrum at 345-355 nm with excitation at 282 nm proves to be a strong indicator of saliva deposited on human skin.

  9. UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

    Science.gov (United States)

    Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

    2016-04-01

    Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

  10. Use of fluorescence spectroscopy to measure molecular autofluorescence in diabetic subjects

    International Nuclear Information System (INIS)

    Diabetes Mellitus (DM) comprises a complex metabolic syndrome, caused by reduced or absent secretion of insulin by pancreatic beta cells, leading to hyperglycemia. Hyperglycemia promotes glycation of proteins and, consequently, the appearance of advanced glycation end products (AGEs). Currently, diabetic patients are monitored by determining levels of glucose and glycated hemoglobin (HbA1c). The complications caused by hyperglycemia may be divided into micro and macrovascular complications, represented by retinopathy, nephropathy, neuropathy and cardiovascular disease. Albumin (HSA) is the most abundant serum protein in the human body and is subject to glycation. The Protoporphyrin IX (PpIX) is the precursor molecule of heme synthesis, structural component of hemoglobin. The in vitro and animals studies have indicated that hyperglycemia promotes a decrease in its concentration in erythrocytes. The fluorescence spectroscopy is a technique widely used in biomedical field. The autofluorescence corresponds to the intrinsic fluorescence present in some molecules, this being associated with the same structure. The aim of this study was to use fluorescence spectroscopy to measure levels of erythrocyte PpIX autofluorescence and AGE-HSA in diabetic and healthy subjects and compare them with levels of blood glucose and HbA1c. This study was conducted with 151 subjects (58 controls and 93 diabetics). Epidemiological data of patients and controls were obtained from medical records. For control subjects, blood glucose levels were obtained from medical records and levels of Hb1Ac obtained by using commercial kits. The determination of the PpIX autofluorescence was performed with excitation at 405 nm and emission at 632 nm. Determination of AGE-HSA was performed with excitation at 370 nm and emission at 455 nm. Approximately 50% of diabetic had micro and macrovascular lesions resulting from hyperglycemia. There were no significant differences in the PpIX emission intensity values

  11. Spectroscopy detection of green and red fluorescent proteins in genetically modified plants using a fiber optics system

    Science.gov (United States)

    Liew, Oi Wah; Asundi, Anand K.; Chen, Jun-Wei; Chew, Yiwen; Yu, Shangjuan; Yeo, Gare H.

    2001-05-01

    In this paper, fiber optic spectroscopy is developed to detect and quantify recombinant green (EGFP) and red (DsRED) fluorescent proteins in vitro and in vivo. The bacterial expression vectors carrying the coding regions of EGFP and DsRED were introduced into Escherichia coli host cells and fluorescent proteins were produced following induction with IPTG. Soluble EGFP and DsRED proteins were isolated from lysed bacterial cells and serially diluted for quantitative analysis by fiber optic spectroscopy. Fluorescence at the appropriate emission wavelengths could be detected up to 64X dilution for EGFP and 40X dilution for DsRED. To determine the capability of spectroscopy detection in vivo, transgenic potato hairy roots expressing EGFP and DsRED were regenerated. This was achieved by cloning the EGFP and DsRED genes into the plant binary vector, pTMV35S, to create the recombinant vectors pGLOWGreen and pGLOWRed. These latter binary vectors were introduced into Agrobacterium rhizogenes strain A4T. Infection of potato cells with transformed agrobacteria was used to insert the fluorescent protein genes into the potato genome. Genetically modified potato cells were then regenerated into hairy roots. A panel of transformed hairy roots expressing varying levels of fluorescent proteins was selected by fluorescence microscopy. We are now assessing the capability of spectroscopic detection system for in vivo quantification of green and red fluorescence levels in transformed roots.

  12. Characterization of simian virus 40 on its infectious entry pathway in cells using fluorescence correlation spectroscopy.

    Science.gov (United States)

    Bernacchi, S; Mueller, G; Langowski, J; Waldeck, W

    2004-11-01

    SV40 (simian virus 40) is a double-stranded DNA virus and is strongly oncogenic in experimental animals. SV40 enters cells by atypical endocytosis mediated by caveolae, transporting the virus to its usual destination, namely the endoplasmic reticulum. The cellular mechanisms of capsid disassembly (uncoating) and deliverance of the viral genome into the cellular nucleus remain unknown. Here, we study (i) the formation of caveolae after viral infection and the diffusion of caveosome vesicles in the cytoplasm and (ii) the capsid disassembly and the mobility of the viral genome on its way to the nucleus, using fluorescence correlation spectroscopy. To follow the viral genome and capsids separately, the histone components of SV40 minichromosomes were labelled with enhanced yellow fluorescent protein and the capsid was labelled with a fluorescent red dye, Alexa568. We characterized the diffusion of caveosomes, the capsid disassembly process in the cytoplasm and the mobility of the viral genome in the nucleus, using two kinds of permissive cells. PMID:15494004

  13. Studies on the formation and stability of triplex DNA using fluorescence correlation spectroscopy.

    Science.gov (United States)

    Hu, Hongyan; Huang, Xiangyi; Ren, Jicun

    2016-05-01

    Triplex DNA has become one of the most useful recognition motifs in the design of new molecular biology tools, therapeutic agents and sophisticated DNA-based nanomaterials because of its direct recognition of natural double-stranded DNA. In this paper, we developed a sensitive and microscale method to study the formation and stability characterization of triplex DNA using fluorescence correlation spectroscopy (FCS). The principle of this method is mainly based on the excellent capacity of FCS for sensitively distinguishing between free single-strand DNA (ssDNA) fluorescent probes and fluorescent probe-double-strand DNA (dsDNA) hybridized complexes. First, we systematically investigated the experimental conditions of triplex DNA formation. Then, we evaluated the equilibrium association constants (Ka ) under different ssDNA probe lengths, composition and pH. Finally, we used FCS to measure the hybridization fraction of a 20-mer perfectly matched ssDNA probe and three single-base mismatched ssDNA probes with 146-mer dsDNA. Our data illustrated that FCS is a useful tool for the direct determination of the thermodynamic parameters of triplex DNA formation and discrimination of a single-base mismatch of triplex DNA without denaturation. Compared with current methods, our method is characterized by high sensitivity, good universality and small sample and reagent requirements. More importantly, our method has the potential to become a platform for triplex DNA research in vitro. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26377428

  14. A novel fluorescence "on-off-on" chemosensor for Hg(2+)via a water-assistant blocking heavy atom effect.

    Science.gov (United States)

    Wu, Chong; Zhao, Jiang-Lin; Jiang, Xue-Kai; Wang, Chuan-Zeng; Ni, Xin-Long; Zeng, Xi; Redshaw, Carl; Yamato, Takehiko

    2016-10-14

    Upper rim pyrene-functionalized hexahomotrioxacalix[3]arene L was synthesized via Click chemistry, and its fluorescence behaviors toward several common metal cations were investigated. L exhibited a significant fluorescence quenching response to Hg(2+) in CH3CN solution, which was unaffected by the coexistence of other competitive metal cations. Thus, L can be utilized as a highly selective and sensitive fluorescent chemosensor for Hg(2+) with a detection limit in the nM level. Interestingly, the quenched fluorescence emission can be successfully revived upon the addition of water. In this process, the heavy atom effect of Hg(2+) can be blocked by further coordination of a water molecule and resulted in the revival of the fluorescence emission of L/Hg(2+) complex. Particularly, other polar solvents such as CH3OH and CH3CH2OH also have the ability to revive the fluorescence emission of the L/Hg(2+) complex, but on a much smaller scale than observed for H2O. The heavy atom effect and blocking thereof were demonstrated within the same system by the use of a C3-symmetric homooxacalix[3]arene scaffold. The present studies provided further evidence for the blocking heavy atom effect.

  15. Probing intra-molecular mechanics of single circularly permuted green fluorescent protein with atomic force microscopy

    International Nuclear Information System (INIS)

    We investigated the mechanical unfolding of single circularly permuted green fluorescent protein (cpGFP) with atomic force microscopy (AFM). The molecule was stretched from its N- and C-termini by an external force causing an elongation of the polypeptide chain up to its full length. The features of the force-extension (F-E) curves were found to depend on the stretching speed. At fast speeds, we detected one peak in the F-E curves before final rupture of the extended molecule, which we interpreted as the unfolding of two terminal halves within cpGFP. We observed several more force peaks in a sawtooth pattern at much slower speeds, and explained the appearance of such force peaks as cooperative unfolding of the hidden sub-structures inside each terminal half

  16. Atomic layer deposition to prevent metal transfer from implants: An X-ray fluorescence study

    Science.gov (United States)

    Bilo, Fabjola; Borgese, Laura; Prost, Josef; Rauwolf, Mirjam; Turyanskaya, Anna; Wobrauschek, Peter; Kregsamer, Peter; Streli, Christina; Pazzaglia, Ugo; Depero, Laura E.

    2015-12-01

    We show that Atomic Layer Deposition is a suitable coating technique to prevent metal diffusion from medical implants. The metal distribution in animal bone tissue with inserted bare and coated Co-Cr alloys was evaluated by means of micro X-ray fluorescence mapping. In the uncoated implant, the migration of Co and Cr particles from the bare alloy in the biological tissues is observed just after one month and the number of particles significantly increases after two months. In contrast, no metal diffusion was detected in the implant coated with TiO2. Instead, a gradient distribution of the metals was found, from the alloy surface going into the tissue. No significant change was detected after two months of aging. As expected, the thicker is the TiO2 layer, the lower is the metal migration.

  17. Pentavalent antimony uptake pathway through erythrocyte membranes: molecular and atomic fluorescence approaches.

    Science.gov (United States)

    Barrera, Camila; López, Silvana; Aguilar, Luis; Mercado, Luis; Bravo, Manuel; Quiroz, Waldo

    2016-04-01

    Previous studies by our group have shown that Sb(V) is able to enter red blood cells in a dynamic process and is reduced to Sb(III) by glutathione. The present study aims to investigate a possible entry pathway for Sb(V) through the erythrocyte membrane. Applying fluorescence spectroscopy studies with Laurdan and diphenylhexatriene (DPH) probes, it was found that there was no interaction between Sb(V) and membrane lipids. By comparing the Sb(V) entry percentages through lipid vesicles and sealed erythrocyte membranes, it was found that Sb(V) required protein channels to pass through the membrane. The competitive inhibition results using HCO3 (-) and Cl(-) showed that the Sb(V) uptake rate through the membrane fell approximately 50-70 % until full inhibition was reached, which was possibly due to the inhibition of the anion exchanger 1 (AE1) channel. Finally, the fluorescence measurements with the 5-iodoacetamidofluorescein (5-IAF) probe showed that Sb(V) interacted with membrane protein SH groups during this process.

  18. Photoassociation spectroscopy of cold alkaline earth atoms near the intercombination line

    OpenAIRE

    Ciurylo, R.; Tiesinga, E.; Kotochigova, S.; P.S. Julienne

    2004-01-01

    The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between $^{1}S_{0}$ and $^{3}P_{1}$ states) of group II atoms are theoretically investigated. As an example we have carried out a calculation for Calcium atoms colliding at ultra low temperatures of 1 mK, 1 $\\mu$K, and 1 nK. Unlike in most current photoassociation spectroscopy the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using Ca--Ca and ...

  19. [Laser resonance ionization spectroscopy of even-parity autoionization states of cerium atom].

    Science.gov (United States)

    Li, Zhi-ming; Zhu, Feng-rong; Zhang, Zi-bin; Ren, Xiang-jun; Deng, Hu; Zhai, Li-hua; Zhang, Li-xing

    2004-12-01

    This paper describes the investigation of even-parity autoionization states of cerium atoms by three-step three-color resonance ionization spectroscopy (RIS). Twenty-seven odd-parity highly excited levels, whose transition probability is high, were used in this research. One hundred and forty-one autoionization states were found by these channels with the third-step laser scanning in the wavelength range of 634-670 nm. The ionization probabilities of different channels, which had higher cross sections, were compared. On the basis of this, eight optimal photoionization schemes of cerium atom have been given. PMID:15828309

  20. Laser-induced Fluorescence and Optical Emission Spectroscopy for the Determination of Reactive Species in the Effluent of Atmospheric Pressure Low Temperature Plasma Jets

    Science.gov (United States)

    Pei, Xuekai; Razavi, Hamid; Lu, Xinpei; Laroussi, Mounir

    2014-10-01

    OH radicals and O atoms are important active species in various applications of room temperature atmospheric pressure plasma jet (RT-APPJ). So the determination of absolute density of OH radicals and O atoms in RT-APPJs is necessary. In this work, the time and spatially resolved OH radicals density of a RT-APPJ are measured using the laser-induced fluorescence (LIF) technology. In addition, the spatial distribution of the emitting species along the axial direction of the jet is of interest and is measured using optical emission spectroscopy. The absolute OH density of the RT-APPJ is about 2.0 × 1013 cm-3 at 5 mm away from the plasma jet nozzle and 1 μs after the discharge. The OH density reaches a maximum when H2O concentration in helium gas flow is about 130ppm. In order to control the OH density, the effect of voltage polarity, applied voltage magnitude, pulse frequency, pulse width on the OH density are also investigated and discussed. O atoms are investigated by TA-LIF. It is demonstrated that the O atoms density reaches a maximum when O2 percent is about 0.3% in pure He and the lifetime of O atoms in RT-APPJ is much longer (up to dozens of ms) than OH radicals.

  1. Intraoperative delineation of primary brain tumors using time-resolved fluorescence spectroscopy

    Science.gov (United States)

    Butte, Pramod V.; Fang, Qiyin; Jo, Javier A.; Yong, William H.; Pikul, Brian K.; Black, Keith L.; Marcu, Laura

    2010-03-01

    The goal of this study is to determine the potential of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as an adjunctive tool for delineation of brain tumor from surrounding normal tissue in order to assist the neurosurgeon in near-complete tumor excision. A time-domain TR-LIFS prototype apparatus (gated photomultiplier detection, fast digitizer) was used for recording tissue autofluorescence in normal cortex (NC), normal white matter (NWM), and various grades of gliomas intraoperatively. Tissue fluorescence was induced with a pulsed nitrogen laser (337 nm, 700 ps), and the intensity decay profiles were recorded in the 360- to 550-nm spectral range (10-nm interval). Histopathological analysis (hematoxylin & eosin) of the biopsy samples taken from the site of TR-LIFS measurements was used for validation of spectroscopic results. Preliminary results on 17 patients demonstrate that normal cortex (N=16) and normal white matter (N=3) show two peaks of fluorescence emission at 390 nm (lifetime=1.8+/-0.3 ns) and 460 nm (lifetime=0.8+/-0.1 ns). The 390-nm emission peak is absent in low-grade glioma (N=5; lifetime=1.1 ns) and reduced in high-grade glioma (N=9; lifetime=1.7+/-0.4 ns). The emission characteristics at 460 nm in all tissues correlated with the nicotinamide adenine dinucleotide fluorescence (peak: 440 to 460 nm lifetime: 0.8 to 1.0 ns). These findings demonstrate the potential of using TR-LIFS as a tool for enhanced delineation of brain tumors during surgery. In addition, this study evaluates similarities and differences between TR-LIFS signatures of brain tumors obtained in vivo and those previously reported in ex vivo brain tumor specimens.

  2. Atomic and molecular photoelectron and Auger-electron-spectroscopy studies using synchrotron radiation

    International Nuclear Information System (INIS)

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were also measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra of the ejected electrons. The double-angle-TOF method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collection efficiency and the elimination of certain systematic errors. An electron spectroscopy study of inner-shell photoexcitation and ionization of Xe, photoelectron angular distributions from H2 and D2, and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

  3. Athermalization in atomic force microscope based force spectroscopy using matched microstructure coupling

    OpenAIRE

    Torun, H.; Finkler, O.; Degertekin, F. L.

    2009-01-01

    The authors describe a method for athermalization in atomic force microscope (AFM) based force spectroscopy applications using microstructures that thermomechanically match the AFM probes. The method uses a setup where the AFM probe is coupled with the matched structure and the displacements of both structures are read out simultaneously. The matched structure displaces with the AFM probe as temperature changes, thus the force applied to the sample can be kept constant without the need for a ...

  4. Mass scaling and non-adiabatic effects in photoassociation spectroscopy of ultracold strontium atoms

    OpenAIRE

    Borkowski, Mateusz; Morzyński, Piotr; Ciuryło, Roman; Julienne, Paul S.; Yan, Mi; DeSalvo, Brian J.; Killian, T. C.

    2014-01-01

    We report photoassociation spectroscopy of ultracold $^{86}$Sr atoms near the intercombination line and provide theoretical models to describe the obtained bound state energies. We show that using only the molecular states correlating with the $^1S_0$$+$$^3P_1$ asymptote is insufficient to provide a mass scaled theoretical model that would reproduce the bound state energies for all isotopes investigated to date: $^{84}$Sr, $^{86}$Sr and $^{88}$Sr. We attribute that to the recently discovered ...

  5. Steady state and time-resolved fluorescence spectroscopy of quinine sulfate dication bound to sodium dodecylsulfate micelles: Fluorescent complex formation

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Sunita; Pant, Debi D., E-mail: ddpant@pilani.bits-pilani.ac.in

    2014-01-15

    Interaction of quinine sulfate dication (QSD) with anionic, sodium dodecylsulphate (SDS) surfactant has been studied at different premicellar, micellar and postmicellar concentrations in aqueous phase using steady state, time-resolved fluorescence and fluorescence anisotropy techniques. At premicellar concentrations of SDS, the decrease in absorbance, appearance of an extra fluorescence band at lower wavelengths and tri-exponential decay behavior of fluorescence, are attributed to complex formation between QSD molecules and surfactant monomers. At postmicellar concentrations the red shift in fluorescence spectrum, increase in quantum yield and increase in fluorescence lifetimes are attributed to incorporation of solute molecules to micelles. At lower concentrations of SDS, a large shift in fluorescence is observed on excitation at the red edge of absorption spectrum and this is explained in terms of distribution of ion pairs of different energies in the ground state and the observed fluorescence lifetime behavior corroborates with this model. The temporal fluorescence anisotropy decay of QSD in SDS micelles allowed determination of restriction on the motion of the fluorophore. All the different techniques used in this study reveal that the photophysics of QSD is very sensitive to the microenvironments of SDS micelles and QSD molecules reside at the water-micelle interface. -- Highlights: • Probe molecule is very sensitive to microenvironment of micelles. • Highly fluorescent ion-pair formation has been observed. • Modulated photophysics of probe molecule in micellar solutions has been observed. • Probe molecules strongly bind with micelles and reside at probe–micelle interface.

  6. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface.

    Science.gov (United States)

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  7. Theoretical analysis of the spectroscopy of atomic Bose-Hubbard systems

    Science.gov (United States)

    Inaba, Kensuke; Yamashita, Makoto

    2016-04-01

    We provide a numerical method to calculate comprehensively the microwave and the laser spectra of ultracold bosonic atoms in optical lattices at finite temperatures. Our formulation is built up with the sum rules, up to the second order, derived from the general principle of spectroscopy. The sum rule approach allows us to discuss the physical origins of a spectral peak shift and also a peak broadening. We find that a spectral broadening of superfluid atoms can be determined from number fluctuations of atoms, while that of normal-state atoms is mainly attributed to quantum fluctuations resulting from hopping of atoms. To calculate spectra at finite temperatures, based on the sum rule approach, we provide a two-mode approximation assuming that spectra of the superfluid and normal state atoms can be calculated separately. Our method can properly deal with multipeak structures of spectra resulting from thermal fluctuations and also coexisting of the superfluid and the normal states. By combining the two-mode approximation with a finite temperature Gutzwiller approximation, we calculate spectra at finite temperatures by considering realistic systems, and the calculated spectra show nice agreements with those in experiments.

  8. Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

    Directory of Open Access Journals (Sweden)

    JELENA J. SAVOVIC

    2001-08-01

    Full Text Available Two atomizers were compared: an N2O–C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

  9. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhuoling; Wang, Hao [Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Sanvito, Stefano [School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2 (Ireland); Hou, Shimin, E-mail: smhou@pku.edu.cn [Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Beida Information Research (BIR), Tianjin 300457 (China)

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p{sub z} atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  10. Photoluminescence Enhancement in Nanotextured Fluorescent SiC Passivated by Atomic Layer Deposited Al2O3 Films

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas;

    2016-01-01

    The influence of thickness of atomic layer deposited Al2O3 films on nano-textured fluorescent 6H-SiC passivation is investigated. The passivation effect on the light emission has been characterized by photoluminescence and time-resolved photoluminescence at room temperature. The results show...

  11. Delaminated graphene at silicon carbide facets: atomic scale imaging and spectroscopy.

    Science.gov (United States)

    Nicotra, Giuseppe; Ramasse, Quentin M; Deretzis, Ioannis; La Magna, Antonino; Spinella, Corrado; Giannazzo, Filippo

    2013-04-23

    Atomic-resolution structural and spectroscopic characterization techniques (scanning transmission electron microscopy and electron energy loss spectroscopy) are combined with nanoscale electrical measurements (conductive atomic force microscopy) to study at the atomic scale the properties of graphene grown epitaxially through the controlled graphitization of a hexagonal SiC(0001) substrate by high temperature annealing. This growth technique is known to result in a pronounced electron-doping (∼10(13) cm(-2)) of graphene, which is thought to originate from an interface carbon buffer layer strongly bound to the substrate. The scanning transmission electron microscopy analysis, carried out at an energy below the knock-on threshold for carbon to ensure no damage is imparted to the film by the electron beam, demonstrates that the buffer layer present on the planar SiC(0001) face delaminates from it on the (112n) facets of SiC surface steps. In addition, electron energy loss spectroscopy reveals that the delaminated layer has a similar electronic configuration to purely sp2-hybridized graphene. These observations are used to explain the local increase of the graphene sheet resistance measured around the surface steps by conductive atomic force microscopy, which we suggest is due to significantly lower substrate-induced doping and a resonant scattering mechanism at the step regions. A first-principles-calibrated theoretical model is proposed to explain the structural instability of the buffer layer on the SiC facets and the resulting delamination.

  12. Precision spectroscopy of Mg atoms in a magneto-optical trap

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A N; Brazhnikov, D V; Shilov, A M; Bagayev, S N [Novosibirsk State University, Novosibirsk (Russian Federation); Bonert, A E [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-06-30

    We report the results of experimental investigations aimed at creation of the optical frequency standard based on magnesium atoms cooled and localised in a magneto-optical trap (MOT). An experimentally realised MOT for magnesium made it possible to obtain a cloud comprising ∼10{sup 6} – 10{sup 7} atoms at a temperature of 3 – 5 mK. The results of ultra-high resolution spectroscopy of intercombination {sup 1}S{sub 0} – {sup 3}P{sub 1} transition for Mg atom are presented, the resonances in time-domain separated optical fields with the half-width of Γ = 500 Hz are recorded, which corresponds to the Q-factor of the reference line Q = ν/Δν ∼ 1.3 × 10{sup 12}. (extreme light fields and their applications)

  13. X-ray absorption spectroscopy in electrical fields: An element-selective probe of atomic polarization

    Science.gov (United States)

    Ney, V.; Wilhelm, F.; Ollefs, K.; Rogalev, A.; Ney, A.

    2016-01-01

    We have studied a range of polar and nonpolar materials using x-ray absorption near-edge spectroscopy (XANES) in external electric fields. An energy shift of the XANES by a few meV/kV is found which scales linearly with the applied voltage, thus being reminiscent of the linear Stark effect. This is corroborated by the consistent presence of this energy shift in polar thin films and bulk crystals and its absence in nonpolar materials as well as in conducting films. The observed energy shift of the XANES is different between two atomic species in one specimen and appears to scale linearly with the atomic number of the studied element. Therefore, XANES in electrical fields opens the perspective to study atomic polarization with element specificity in a range of functional materials.

  14. Composite pulses in Hyper-Ramsey spectroscopy for the next generation of atomic clocks

    CERN Document Server

    Zanon-Willette, T; Yudin, V I; Taichenachev, A V

    2016-01-01

    The next generation of atomic frequency standards based on an ensemble of neutral atoms or a single-ion will provide very stringent tests in metrology, applied and fundamental physics requiring a new step in very precise control of external systematic corrections. In the proceedings of the 8th Symposium on Frequency Standards and Metrology, we present a generalization of the recent Hyper-Ramsey spectroscopy with separated oscillating fields using composites pulses in order to suppress field frequency shifts induced by the interrogation laser itself. Sequences of laser pulses including specific selection of phases, frequency detunings and durations are elaborated to generate spectroscopic signals with a strong reduction of the light-shift perturbation by off resonant states. New optical clocks based on weakly allowed or completely forbidden transitions in atoms, ions, molecules and nuclei will benefit from these generalized Ramsey schemes to reach relative accuracies well below the 10$^{-18}$ level.

  15. Composite pulses in Hyper-Ramsey spectroscopy for the next generation of atomic clocks

    Science.gov (United States)

    Zanon-Willette, T.; Minissale, M.; Yudin, V. I.; Taichenachev, A. V.

    2016-06-01

    The next generation of atomic frequency standards based on an ensemble of neutral atoms or a single-ion will provide very stringent tests in metrology, applied and fundamental physics requiring a new step in very precise control of external systematic corrections. In the proceedings of the 8th Symposium on Frequency Standards and Metrology, we present a generalization of the recent Hyper-Ramsey spectroscopy with separated oscillating fields using composites pulses in order to suppress field frequency shifts induced by the interrogation laser itself. Sequences of laser pulses including specific selection of phases, frequency detunings and durations are elaborated to generate spectroscopic signals with a strong reduction of the light-shift perturbation by off resonant states. New optical clocks based on weakly allowed or completely forbidden transitions in atoms, ions, molecules and nuclei will benefit from these generalized Ramsey schemes to reach relative accuracies well below the 10-18 level.

  16. The Effect of a Fluorophore Photo-Physics on the Lipid Vesicle Diffusion Coefficient Studied by Fluorescence Correlation Spectroscopy.

    Science.gov (United States)

    Drabik, Dominik; Przybyło, Magda; Sikorski, Aleksander; Langner, Marek

    2016-03-01

    Fluorescence Correlation Spectroscopy (FCS) is a technique, which allows determination of the diffusion coefficient and concentration of fluorescent objects suspended in the solution. The measured parameter is the fluctuation of the fluorescence signal emitted by diffusing molecules. When 100 nm DOPC vesicles labeled with various fluorescent dyes (Fluorescein-PE, NBD-PE, Atto488 DOPE or βBodipy FL) were measured, different values of diffusion coefficients have been obtained. These diffusion coefficients were different from the expected values measured using the dynamic light scattering method (DLS). The FCS was initially developed for solutions containing small fluorescent molecules therefore the observed inconsistency may result from the nature of vesicle suspension itself. The duration of the fluorescence signal may depend on the following factors: the exposure time of the labeled object to the excitation beam, the photo-physical properties (e.g., stability) of a fluorophore, the theoretical model used for the calculations of the diffusion coefficient and optical properties of the vesicle suspension. The diffusion coefficients determined for differently labeled liposomes show that its dependence on vesicle size and quantity of fluorescent probed used for labeling was significant demonstrating that the fluorescence properties of the fluorophore itself (bleaching and/or blinking) were critical factors for a correct outcome of FCS experiment. The new, based on combined FCS and DLS measurements, method for the determination of the focal volume prove itself to be useful for the evaluation of a fluorescence dye with respect to its applicability for FCS experiment. PMID:26695945

  17. Super-resolution fluorescence imaging and correlation spectroscopy: Principles and examples of application

    Directory of Open Access Journals (Sweden)

    Jovanović-Talisman Tijana

    2013-01-01

    Full Text Available Self-organization of cell-surface receptors in structurally distinct domains in the plasma membrane is of vital interest for correct cellular signaling. However, this dynamic process is difficult to study in cells with sufficiently high temporal and spatial resolution. We present here two quantitative high-resolution methods with single-molecule sensitivity, Fluorescence Correlation Spectroscopy (FCS and pair-correlation Photoactivated Localization Microscopy (pcPALM, which enable nondestructive study of receptor diffusion and lateral organization at the nanoscale level. We introduce here the methods and review their application in studies of lateral organization of G Protein-Coupled Receptors (GPCRs. Examples from our own work on opioid receptor lateral organization are presented in order to illustrate the most recent advances in the field. [Projekat Ministarstva nauke Republike Srbije, br. 172015 i br. 45001

  18. Fluorescence spectroscopy coupled with PARAFAC and PLS DA for characterization and classification of honey.

    Science.gov (United States)

    Lenhardt, Lea; Bro, Rasmus; Zeković, Ivana; Dramićanin, Tatjana; Dramićanin, Miroslav D

    2015-05-15

    Fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) and Partial least squares Discriminant Analysis (PLS DA) were used for characterization and classification of honey. Excitation emission spectra were obtained for 95 honey samples of different botanical origin (acacia, sunflower, linden, meadow, and fake honey) by recording emission from 270 to 640 nm with excitation in the range of 240-500 nm. The number of fluorophores present in honey, excitation and emission spectra of each fluorophore, and their relative concentration are determined using a six-component PARAFAC model. Emissions from phenolic compounds and Maillard reaction products exhibited the largest difference among classes of honey of different botanical origin. The PLS DA classification model, constructed from PARAFAC model scores, detected fake honey samples with 100% sensitivity and specificity. Honey samples were also classified using PLS DA with errors of 0.5% for linden, 10% for acacia, and about 20% for both sunflower and meadow mix. PMID:25577082

  19. Monitoring laboratory-scale bioventing using synchronous scan fluorescence spectroscopy: analysis of the vapor phase.

    Science.gov (United States)

    Bachman, J; Kanan, S M; Patterson, H H

    2001-01-01

    Bioventing is an improved method of soil remediation that is being used with increasing frequency. In this paper, we refine techniques to measure the progress of petroleum hydrocarbon decomposition by monitoring vapor phase composition with synchronous scan fluorescence spectroscopy (SSFS). Analysis of the vapor phase has advantages compared to standard extraction techniques that require extensive sample handling and clean up. For comparison, hydrocarbon contamination in the soil was measured by analysis of Soxhlet extractions with gas chromatography-mass spectrometry (GC-MS). Comparison of the GC-MS and SSFS data showed that changes in hydrocarbon composition measured in the vapor phase provide an accurate measure of decomposition reactions taking place in the soil.

  20. Vectorized data acquisition and fast triple-correlation integrals for Fluorescence Triple Correlation Spectroscopy

    Science.gov (United States)

    Ridgeway, William K.; Millar, David P.; Williamson, James R.

    2013-04-01

    Fluorescence Correlation Spectroscopy (FCS) is widely used to quantify reaction rates and concentrations of molecules in vitro and in vivo. We recently reported Fluorescence Triple Correlation Spectroscopy (F3CS), which correlates three signals together instead of two. F3CS can analyze the stoichiometries of complex mixtures and detect irreversible processes by identifying time-reversal asymmetries. Here we report the computational developments that were required for the realization of F3CS and present the results as the Triple Correlation Toolbox suite of programs. Triple Correlation Toolbox is a complete data analysis pipeline capable of acquiring, correlating and fitting large data sets. Each segment of the pipeline handles error estimates for accurate error-weighted global fitting. Data acquisition was accelerated with a combination of off-the-shelf counter-timer chips and vectorized operations on 128-bit registers. This allows desktop computers with inexpensive data acquisition cards to acquire hours of multiple-channel data with sub-microsecond time resolution. Off-line correlation integrals were implemented as a two delay time multiple-tau scheme that scales efficiently with multiple processors and provides an unprecedented view of linked dynamics. Global fitting routines are provided to fit FCS and F3CS data to models containing up to ten species. Triple Correlation Toolbox is a complete package that enables F3CS to be performed on existing microscopes. Catalogue identifier: AEOP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOP_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 50189 No. of bytes in distributed program, including test data, etc.: 6135283 Distribution format: tar.gz Programming language: C/Assembly. Computer: Any with GCC and

  1. DNA binding activity of Anabaena sensory rhodopsin transducer probed by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Kim, Sung Hyun; Kim, So Young; Jung, Kwang-Hwan; Kim, Doseok

    2015-01-01

    Anabaena sensory rhodopsin transducer (ASRT) is believed to be a major player in the photo-signal transduction cascade, which is triggered by Anabaena sensory rhodopsin. Here, we characterized DNA binding activity of ASRT probed by using fluorescence correlation spectroscopy. We observed clear decrease of diffusion coefficient of DNA upon binding of ASRT. The dissociation constant, K(D), of ASRT to 20 bp-long DNA fragments lied in micro-molar range and varied moderately with DNA sequence. Our results suggest that ASRT may interact with several different regions of DNA with different binding affinity for global regulation of several genes that need to be activated depending on the light illumination.

  2. A multi-channel monolithic Ge detector system for fluorescence x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Construction and performance of a monolithic quad-pixel Ge detector for fluorescence x-ray absorption spectroscopy (XAS) at synchrotron radiation sources are described. The detector semiconductor element has an active surface area of 4.0 cm2 which is electrically separated into four 1.0 cm2 pixels, with little interfacial dead volume. Spatial response of the array shows that cross-talk between adjacent pixels is 55Fe test source (MnKα, 5.9 keV), energy resolution of better than 200 eV is achieved with a 4 μsec peaking time. At 0.5 μsec peaking time, pulse pileup results in a 75% throughput efficiency for an incoming count rate of 100 kHz. Initial XAS fluoresncece measurements at the beamline 4 wiggler end stations at SSRL show that the detector system has several advantages over commercial x-ray spectrometers for low-concentration counting

  3. Time-resolved laser fluorescence spectroscopy of UO2(CO3)3(4-).

    Science.gov (United States)

    Jung, E C; Cho, H-R; Baik, M H; Kim, H; Cha, W

    2015-11-21

    The objective of the present study is to examine the luminescence characteristics of UO2(CO3)3(4-) in detail using time-resolved laser fluorescence spectroscopy. The peak wavelengths and lifetime of UO2(CO3)3(4-) were determined at room temperature using the two excitation laser wavelengths of 266 and 448 nm. The peak wavelengths in the luminescence spectrum exhibited hypsochromic shifts compared with those of UO2(2+). The lifetime determined from several samples containing various uranium concentrations was 8.9 ± 0.8 ns. Explanations for the hindrance to the observation of the luminescence spectrum of UO2(CO3)3(4-) in previous investigations are discussed. The representative experimental parameters, which might interrupt the measurement of weak luminescence, are the insertion delay time of the detection device, the overlapped luminescence of the background materials and the primary inner filter effect in the sample solution.

  4. Fluorescence spectroscopy of single molecules at room temperature and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Taekjip

    1996-12-01

    We performed fluorescence spectroscopy of single and pairs of dye molecules on a surface at room temperature. Near field scanning optical microscope (NSOM) and far field scanning optical microscope with multi-color excitation/detection capability were built. The instrument is capable of optical imaging with 100nm resolution and has the sensitivity necessary for single molecule detection. A variety of dynamic events which cannot be observed from an ensemble of molecules is revealed when the molecules are probed one at a time. They include (1) spectral jumps correlated with dark states, (2) individually resolved quantum jumps to and from the meta-stable triplet state, (3) rotational jumps due to desorption/readsorption events of single molecules on the surface. For these studies, a computer controlled optical system which automatically and rapidly locates and performs spectroscopic measurements on single molecules was developed. We also studied the interaction between closely spaced pairs of molecules. In particular, fluorescence resonance energy transfer between a single resonant pair of donor and acceptor molecules was measured. Photodestruction dynamics of the donor or acceptor were used to determine the presence and efficiency of energy transfer Dual molecule spectroscopy was extended to a non-resonant pair of molecules to obtain high resolution differential distance information. By combining NSOM and dual color scheme, we studied the co-localization of parasite proteins and host proteins on a human red blood cell membrane infected with malaria. These dual-molecule techniques can be used to measure distances, relative orientations, and changes in distances/orientations of biological macromolecules with very good spatial, angular and temporal resolutions, hence opening new capabilities in the study of such systems.

  5. The use of one- and two- photon induced fluorescence spectroscopy for the optical characterization of carcinogenic aflatoxins

    Science.gov (United States)

    Smeesters, L.; Meulebroeck, W.; Raeymaekers, S.; Thienpont, H.

    2014-09-01

    Carcinogenic and toxic contaminants in food and feed products are nowadays mostly detected by destructive, time-consuming chemical analyses, like HPLC and LC-MS/MS methods. However, as a consequence of the severe and growing regulations on food products by the European Union, there arose an increased demand for the ultra-fast, high-sensitive and non-destructive detection of contaminants in food and feed products. Therefore, we have investigated fluorescence spectroscopy for the characterization of carcinogenic aflatoxins. With the use of a tunable titanium-sapphire laser in combination with second and third harmonic wavelength generation, both one- and two-photon induced fluorescence excitation wavelengths could be generated using the same setup. We characterized and compared the one- and two-photon induced fluorescence spectra of pure aflatoxin powder, after excitation with 365nm and 730nm respectively. Moreover, we investigated the absolute fluorescence intensity as function of the excitation power density. Afterwards, we applied our characterization setup to the detection of aflatoxins in maize grains. The fluorescence spectra of both healthy and contaminated maize samples were experimentally characterized. In addition to the fluorescence spectrum of the pure aflatoxin, we observed an unwanted influence of the intrinsic fluorescence of the maize. Depending on the excitation wavelength, a varying contrast between the fluorescence spectra of the healthy and contaminated samples was obtained. After a comparison of the measured fluorescence signals, a detection criterion for the optical identification of the contaminated maize samples could be defined. As a result, this illustrates the use of fluorescence spectroscopy as a valuable tool for the non-destructive, real-time and high-sensitive detection of aflatoxins in maize.

  6. Fluorescence correlation spectroscopy to measure the metabolism of high-density lipoprotein

    Science.gov (United States)

    Deitrick, Russell; Gibson, Emily; Razzaghi, Hamid

    2009-10-01

    High-density lipoprotein (HDL), referred to as the ``good cholesterol'', carries free cholesterol to the liver to be filtered from the bloodstream and is important to our understanding of atherosclerosis. HDL is metabolized in part by the enzyme Endothelial Lipase (EL). With this project we will use fluorescence correlation spectroscopy (FCS) to study the metabolism of HDL by EL comparing wild type with different genetic mutations. FCS is an advanced microscopy technique in which we record fluctuations in the fluorescence of dye-labeled molecules (in this case, HDL labeled with Nile Red) as they freely diffuse through a small focal volume. This data can be analyzed mathematically using the cross-correlation function, from which we can ultimately ascertain much information. In our case, we are interested in the diffusion coefficient which, via the Stokes-Einstein relation for a sphere, we can determine the size of HDL as it undergoes the process of metabolism. Preliminary results seem to indicate that the metabolic process occurs very quickly, that the final size of HDL depends primarily on the concentration of EL, and that the wild and mutant variants of EL have a similar effectiveness. In following experiments, we hope to investigate these relationships further.

  7. Light adaptation of the unicellular red alga, Cyanidioschyzon merolae, probed by time-resolved fluorescence spectroscopy.

    Science.gov (United States)

    Ueno, Yoshifumi; Aikawa, Shimpei; Kondo, Akihiko; Akimoto, Seiji

    2015-08-01

    Photosynthetic organisms change the quantity and/or quality of their pigment-protein complexes and the interactions among these complexes in response to light conditions. In the present study, we analyzed light adaptation of the unicellular red alga Cyanidioschyzon merolae, whose pigment composition is similar to that of cyanobacteria because its phycobilisomes (PBS) lack phycoerythrin. C. merolae were grown under different light qualities, and their responses were measured by steady-state absorption, steady-state fluorescence, and picosecond time-resolved fluorescence spectroscopies. Cells were cultivated under four monochromatic light-emitting diodes (blue, green, yellow, and red), and changes in pigment composition and energy transfer were observed. Cells grown under blue and green light increased their relative phycocyanin levels compared with cells cultured under white light. Energy-transfer processes to photosystem I (PSI) were sensitive to yellow and red light. The contribution of direct energy transfer from PBS to PSI increased only under yellow light, while red light induced a reduction in energy transfer from photosystem II to PSI and an increase in energy transfer from light-harvesting chlorophyll protein complex I to PSI. Differences in pigment composition, growth, and energy transfer under different light qualities are discussed. PMID:25577254

  8. Heterogeneity in binary mixtures of dimethyl sulfoxide and glycerol: Fluorescence correlation spectroscopy

    Science.gov (United States)

    Chattoraj, Shyamtanu; Chowdhury, Rajdeep; Ghosh, Shirsendu; Bhattacharyya, Kankan

    2013-06-01

    Diffusion of four coumarin dyes in a binary mixture of dimethyl sulfoxide (DMSO) and glycerol is studied using fluorescence correlation spectroscopy (FCS). The coumarin dyes are C151, C152, C480, and C481. In pure DMSO, all the four dyes exhibit a very narrow (almost uni-modal) distribution of diffusion coefficient (Dt). In contrast, in the binary mixtures all of them display a bimodal distribution of Dt with broadly two components. One of the components of Dt corresponds to the bulk viscosity. The other one is similar to that in pure DMSO. This clearly indicates the presence of two distinctly different nano-domains inside the binary mixture. In the first, the micro-environment of the solute consists of both DMSO and glycerol approximately at the bulk composition. The other corresponds to a situation where the first layer of the solute consists of DMSO only. The burst integrated fluorescence lifetime (BIFL) analysis also indicates presence of two micro-environments one of which resembles DMSO. The relative contribution of the DMSO-like environment obtained from the BIFL analysis is much larger than that obtained from FCS measurements. It is proposed that BIFL corresponds to an instantaneous environment in a small region (a few nm) around the probe. FCS, on the contrary, describes the long time trajectory of the probes in a region of dimension ˜200 nm. The results are explained in terms of the theory of binary mixtures and recent simulations of binary mixtures containing DMSO.

  9. Fluorescence spectroscopy for monitoring reduction of natural organic matter and halogenated furanone precursors by biofiltration.

    Science.gov (United States)

    Peleato, Nicolás M; McKie, Michael; Taylor-Edmonds, Lizbeth; Andrews, Susan A; Legge, Raymond L; Andrews, Robert C

    2016-06-01

    The application of fluorescence spectroscopy to monitor natural organic matter (NOM) reduction as a function of biofiltration performance was investigated. This study was conducted at pilot-scale where a conventional media filter was compared to six biofilters employing varying enhancement strategies. Overall reductions of NOM were identified by measuring dissolved organic carbon (DOC), and UV absorbance at 254 nm, as well as characterization of organic sub-fractions by liquid chromatography-organic carbon detection (LC-OCD) and parallel factors analysis (PARAFAC) of fluorescence excitation-emission matrices (FEEM). The biofilter using granular activated carbon media, with exhausted absorptive capacity, was found to provide the highest removal of all identified PARAFAC components. A microbial or processed humic-like component was found to be most amenable to biodegradation by biofilters and removal by conventional treatment. One refractory humic-like component, detectable only by FEEM-PARAFAC, was not well removed by biofiltration or conventional treatment. All biofilters removed protein-like material to a high degree relative to conventional treatment. The formation potential of two halogenated furanones, 3-chloro-4(dichloromethyl)-2(5H)-furanone (MX) and mucochloric acid (MCA), as well as overall treated water genotoxicity are also reported. Using the organic characterization results possible halogenated furanone and genotoxicity precursors are identified. Comparison of FEEM-PARAFAC and LC-OCD results revealed polysaccharides as potential MX/MCA precursors. PMID:27016810

  10. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    Science.gov (United States)

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  11. Comparative Studies of Interactions between Fluorodihydroquinazolin Derivatives and Human Serum Albumin with Fluorescence Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2016-10-01

    Full Text Available In the present study, 3-(fluorobenzylideneamino-6-chloro-1-(3,3-dimethylbutanoyl-phenyl-2,3-dihydroquinazolin-4(1H-one (FDQL derivatives have been designed and synthesized to study the interaction between fluorine substituted dihydroquinazoline derivatives with human serum albumin (HSA using fluorescence, circular dichroism and Fourier transform infrared spectroscopy. The results indicated that the FDQL could bind to HSA, induce conformation and the secondary structure changes of HSA, and quench the intrinsic fluorescence of HSA through a static quenching mechanism. The thermodynamic parameters, ΔH, ΔS, and ΔG, calculated at different temperatures, revealed that the binding was through spontaneous and hydrophobic forces and thus played major roles in the association. Based on the number of binding sites, it was considered that one molecule of FDQL could bind to a single site of HSA. Site marker competition experiments indicated that the reactive site of HSA to FDQL mainly located in site II (subdomain IIIA. The substitution by fluorine in the benzene ring could increase the interactions between FDQL and HSA to some extent in the proper temperature range through hydrophobic effect, and the substitution at meta-position enhanced the affinity greater than that at para- and ortho-positions.

  12. PREFACE: Heavy-Ion Spectroscopy and QED Effects in Atomic Systems

    Science.gov (United States)

    Lindgren, Ingvar; Martinson, Indrek; Schuch, Reinhold

    1993-01-01

    now essentially solved. The experimental accuracy is already so high that also higher-order QED effects become observable, and several groups are now active in trying to evaluate such effects from first principles. Another related field where substantial progress has recently been made involves precision measurements of X-ray transitions. This has created an interest in the study of deep inner holes in heavy atoms, where large relativistic and QED effects appear. These effects are as large as in corresponding highly charged ions, but the interpretation requires that the many-body effects from the surrounding electrons are accurately extracted. This is a big challenge at present. Atomic collision physics with highly charged ions has been dominated in recent years by the search for a possibility to describe electron-electron interaction within the dynamics of collisions. The experiments on multielectron transfer reactions with highly charged ions posed in this respect quite a challenge to the theory. The models developed to meet this were often based on methods and terminologies developed for describing the inter-electronic interactions in atomic structure. This caused many controversial discussions, also during this symposium. A new and fast rising field is the interaction of highly charged ions with solid surfaces. This may become an important link between atomic physics and condensed-matter physics, stimulated by the opportunity to study effects in coupled many-body systems present in the case when a large amount of electrons is transferred from the solid to each single ion. Furtheron, collision experiments with cooled ion beams in ion storage rings open new dimensions also for atomic spectroscopy. It appears possible that transition and binding energies can be measured in recombination of very heavy ions with a better quality than by conventional Auger electron or X-ray spectroscopy. Obviously, it is not possible to cover all the fields mentioned here in a single

  13. Laser-Induced Fluorescence Spectroscopy of Jet-Cooled t-Butoxy.

    Science.gov (United States)

    Liu, Jinjun; Reilly, Neil J; Mason, Amy; Miller, Terry A

    2015-12-10

    The vibrational structures of the Ã(2)A1 and X̃(2)E states of t-butoxy were obtained in jet-cooled laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectroscopic measurements. The observed transitions are assigned based on vibrational frequencies calculated using the complete active space self-consistent field (CASSCF) method and the predicted Franck-Condon factors. The spin-orbit splitting was measured to be 36(5) cm(-1) for the lowest vibrational level of the ground (X̃(2)E) state, which is significantly smaller than that of methoxy, and increases with increasing vibrational quantum number of the CO stretch mode. Vibronic analysis of the DF spectra suggests that Jahn-Teller active modes of the ground-state t-butoxy radical are similar to those of methoxy and would be the same if methyl groups were replaced by hydrogen atoms. The rotational and fine structure of the LIF transition to the first CO stretch overtone level of the Ã(2)A1 state has been simulated using a spectroscopic model first proposed for methoxy, yielding an accurate determination of the rotational constants of both à and X̃ states. PMID:26524342

  14. X-Ray Fluorescence and Laser-Induced Breakdown Spectroscopy analysis of Roman silver denarii

    Energy Technology Data Exchange (ETDEWEB)

    Pardini, L. [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); El Hassan, A. [National Institute for Laser- Enhanced Sciences (NILES), Cairo University Giza (Egypt); Ferretti, M. [Istituto per le Tecnologie Applicate ai Beni Culturali, Area della Ricerca del CNR di Montelibretti Roma (Italy); Foresta, A.; Legnaioli, S.; Lorenzetti, G. [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Nebbia, E. [Universita degli Studi di Torino (Italy); Catalli, F. [Monetiere di Firenze, Museo Archeologico Nazionale Firenze (Italy); Harith, M.A. [National Institute for Laser- Enhanced Sciences (NILES), Cairo University Giza (Egypt); Diaz Pace, D. [Institute of Physics ' Arroyo Seco' , Faculty of Science, Tandil (Argentina); Anabitarte Garcia, F. [Photonics Engineering Group, University of Cantabria, Santander (Spain); Scuotto, M. [Dipartimento di Scienze Archeologiche, Via Galvani 1, 56126 Pisa (Italy); Palleschi, V., E-mail: vincenzo.palleschi@cnr.it [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Dipartimento di Scienze Archeologiche, Via Galvani 1, 56126 Pisa (Italy)

    2012-08-15

    In this paper we present the results of a study performed on a large collection of silver Roman republican denarii, encompassing about two centuries of history. The joint use of Laser-Induced Breakdown Spectroscopy (LIBS) and X-Ray Fluorescence (XRF) spectroscopy allowed for an accurate determination of the coins' elemental composition; the measurements, performed mostly in situ at the 'Monetiere' in Florence, revealed a striking connection between the 'quality' of the silver alloy and some crucial contemporary events. This finding was used to classify a group of denarii whose dating was otherwise impossible. The comparison with other contemporary denarii disproves a recent theory on the origin of the so called 'serrated' denarii (denarii showing notched chisel marks on the edge of the coin). - Highlights: Black-Right-Pointing-Pointer We studied a large collection of Roman republican silver denarii. Black-Right-Pointing-Pointer XRF and LIBS allowed to determine the precious metal content of the coins. Black-Right-Pointing-Pointer A correlation of the 'quality' of the alloy with some contemporary events was found. Black-Right-Pointing-Pointer The study allowed to controvert a recent theory on the so called 'serrated' denarii.

  15. Laser Induced Fluorescence Spectroscopy of Neutral and Ionized Polycyclic Aromatic Hydrocarbons in a Cosmic Simulation Chamber

    Science.gov (United States)

    Bejaoui, Salma; Salama, Farid

    2015-08-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are considered the best carriers to account for the ubiquitous infrared emission bands. PAHs have also been proposed as candidates to explain the diffuse interstellar bands (DIBs), a series of absorption features seen on the interstellar extinction curve and are plausible carriers for the extended red emission (ERE), a photoluminescent process associated with a wide variety of interstellar environments. Extensive efforts have been devoted over the past two decades to characterize the physical and chemical properties of PAH molecules and ions in space. Absorption spectra of PAH molecules and ions trapped in solid matrices have been compared to the DIBs [1, 2]. Absorption spectra of several cold, isolated gas-phase PAHs have also been measured under experimental conditions that mimic the interstellar conditions [see 3 for a review]. The purpose of this study is to provide a new dimension to the existing spectroscopic database of neutral and single ionized PAHs that is largely based on absorption spectra by adding emission spectroscopy data. The measurements are based on the laser-induced fluorescence (LIF) technique [4] and are performed with the Pulsed Discharge Nozzle (PDN) of the COSmIC laboratory facility at NASA Ames laboratory. The PDN generates plasma in a free supersonic jet expansion to simulate the physical and the chemical conditions in interstellar environments. We focus, here, on the fluorescence spectra of large neutral PAHs and their cations where there is a lack of fluorescence spectroscopy data. The astronomical implications of the data (e.g., ERE) are examinedReferences[1] F. Salama, E. Bakes, L.J. Allamandola, A.G.G.M. Tielens, Astrophys. J., 458 (1996) p.621[2] F. Salama, The ISO Revolution, EDP Sciences, Les Ulis, France (1999) p.65[3] Salama F., In Organic Matter in Space, IAU Symposium 251, Kwok & Sandford Eds.Cambridge University Press,4, S251,(2008), p. 357 (2008) and references therein.[4

  16. Probing an Excited-State Atomic Transition Using Hyperfine Quantum Beat Spectroscopy

    CERN Document Server

    Wade, Christopher G; Keaveney, James; Adams, Charles S; Weatherill, Kevin J

    2014-01-01

    We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P$_{3/2}$ state to the 7S$_{1/2}$ state. We observe quantum beats in the fluorescence from the 6P$_{3/2}$ state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P$_{3/2}$, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved.

  17. Investigation on the photo-induced de-oxygenation process of myoglobin in aqueous solution by use of fluorescence spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A photo-induced de-oxygenation process of myoglobin (Mb) in aqueous solution was investigated by use of fluorescence spectroscopy. The spectra are characterized by the fluorescence intensity declining gradually after each scan,and the decay of fluorescence intensity being significant in each scan,which is assigned to the release of oxygen from the opening of the heme-pockets induced by illumination. More illumination will cause more release of oxygen; if the temperature of an Mb solution is increased when it is illuminated,the rate of de-oxygenation will be higher. It was found that ligand-oxygen in Fe-porphyrin could be removed from Mb by nitrogen. This indicates that the interac-tion between oxy-Mb and other different gases can be tested by the method of fluorescence spectros-copy. In addition,fluorescence spectroscopy can be employed to probe the energy transfer between Fe-porphyrin and tryptophan or tyrosine in Mb molecules.

  18. Organic Light Emitting Device as a fluorescence spectroscopy's light source : one step towards the lab-on-a-chip device

    Science.gov (United States)

    Camou, S.; Kitamura, M.; Gouy, Jean-Philippe; Fujita, Hiroyuki; Arakawa, Yasuhiko; Fujii, Teruo

    2003-02-01

    Many papers were recently dedicated to the lab-on-a-chip applications, where all the basic elements should be integrated directly onto the microchip. The fluorescence spectroscopy is mostly used as a detection method due to its high reliability and sensitivity, but requires light source and photo-detector. For the first time, we then propose to use Organic material Light Emitting Diode (OLED) to supply a light source for the optical detection based on fluorescence spectroscopy. By combining this OLED with micro-fluidic channels patterned in PDMS layer, the integration of light source on the chip is then achieved. First, the ability of Organic Material to excite fluorescent response from dye is demonstrated. Then, some configurations are described in order to decrease the major drawbacks that have to be solved before applying such kind of devices.

  19. Velocity selective bi-polarization spectroscopy for laser cooling of metastable Krypton atoms

    CERN Document Server

    Kale, Y B; Singh, S; Mishra, S R; Rawat, H S

    2014-01-01

    We report a velocity selective bi-polarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable Krypton (Kr*) atoms, overlaps with a pair of counter-propagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in VS-BPS signal. The spectral shifting in VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy...

  20. Non-linear Spectroscopy of Sr Atoms in an Optical Cavity for Laser Stabilization

    CERN Document Server

    Christensen, Bjarke T R; Schäffer, Stefan A; Westergaard, Philip G; Ye, Jun; Holland, Murray; Thomsen, Jan W

    2015-01-01

    We study the non-linear interaction of a cold sample of strontium-88 atoms coupled to a single mode of a low finesse optical cavity in the so-called bad cavity limit and investigate the implications for applications to laser stabilization. The atoms are probed on the weak inter-combination line $\\lvert 5s^{2} \\, ^1 \\textrm{S}_0 \\rangle \\,-\\, \\lvert 5s5p \\, ^3 \\textrm{P}_1 \\rangle$ at 689 nm in a strongly saturated regime. Our measured observables include the atomic induced phase shift and absorption of the light field transmitted through the cavity represented by the complex cavity transmission coefficient. We demonstrate high signal-to-noise-ratio measurements of both quadratures - the cavity transmitted phase and absorption - by employing FM spectroscopy (NICE-OHMS). We also show that when FM spectroscopy is employed in connection with a cavity locked to the probe light, observables are substantially modified compared to the free space situation where no cavity is present. Furthermore, the non-linear dynami...

  1. Taking nanomedicine teaching into practice with atomic force microscopy and force spectroscopy.

    Science.gov (United States)

    Carvalho, Filomena A; Freitas, Teresa; Santos, Nuno C

    2015-12-01

    Atomic force microscopy (AFM) is a useful and powerful tool to study molecular interactions applied to nanomedicine. The aim of the present study was to implement a hands-on atomic AFM course for graduated biosciences and medical students. The course comprises two distinct practical sessions, where students get in touch with the use of an atomic force microscope by performing AFM scanning images of human blood cells and force spectroscopy measurements of the fibrinogen-platelet interaction. Since the beginning of this course, in 2008, the overall rating by the students was 4.7 (out of 5), meaning a good to excellent evaluation. Students were very enthusiastic and produced high-quality AFM images and force spectroscopy data. The implementation of the hands-on AFM course was a success, giving to the students the opportunity of contact with a technique that has a wide variety of applications on the nanomedicine field. In the near future, nanomedicine will have remarkable implications in medicine regarding the definition, diagnosis, and treatment of different diseases. AFM enables students to observe single molecule interactions, enabling the understanding of molecular mechanisms of different physiological and pathological processes at the nanoscale level. Therefore, the introduction of nanomedicine courses in bioscience and medical school curricula is essential.

  2. Photo-initiated dynamics and spectroscopy of the deprotonated Green Fluorescent Protein chromophore

    DEFF Research Database (Denmark)

    Bochenkova, Anastasia; Andersen, Lars Henrik

    2013-01-01

    . Knowledge of intrinsic properties of the GFP photoabsorbing molecular unit is a prerequisite in understanding the atomic-scale interactions that play a key role for the diverse functioning of these proteins. Here, we show how recent developments in action and photoelectron spectroscopy combined with state......-of-the-art electronic structure theory provide valuable insights into photo-initiated quantum dynamics and enable to disclose mechanisms of multiple intrinsic excited-state decay channels in the bare GFP chromophore anion. When taken out of the protein, the deprotonated chromophore exhibits the ultrafast excited state...... efficiently compete with each other in spite of their inherently different intrinsic timescales. The reason behind this is an efficient coupling between the nuclear and electronic motion in the photo-initiated dynamics, where the energy may be transferred from nuclei to electrons and from electrons to nuclei...

  3. Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Mariela N.M.; Cervera, Maria L.; Guardia, Miguel de la, E-mail: m.luisa.cervera@uv.e [University of Valencia, Valencia (Spain). Dept. of Analytical Chemistry

    2011-07-01

    A non-chromatographic fast, sensitive and easy method has been developed for the determination of Sb(III), Sb(V), Te(IV) and Te(VI) in cereal samples. The procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (HG AFS). Preliminary studies were made in order to get the best extraction efficiency using 1 mol L{sup -1} phosphoric acid, 1 mol L{sup -1} nitric acid, aqua regia, 1 mol L{sup -1} sulfuric acid and 6 mol L{sup -1} hydrochloric acid. The extraction with aqua regia showed a clear interconversion of the species during the process, being H{sub 2}SO{sub 4} the best extractant with efficiencies greater than 90% from the total content of Sb and Te quantified previously and without species interconversion. This point was checked by recovery experiments at different spiked levels. The method provided limits of detection values from 0.1 to 0.5 ng g{sup -1} with relative standard deviation values from 5.4 to 9.2% of 10 independent analysis of samples containing few ng g-1 of Sb and Te species. (author)

  4. Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    A non-chromatographic fast, sensitive and easy method has been developed for the determination of Sb(III), Sb(V), Te(IV) and Te(VI) in cereal samples. The procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (HG AFS). Preliminary studies were made in order to get the best extraction efficiency using 1 mol L-1 phosphoric acid, 1 mol L-1 nitric acid, aqua regia, 1 mol L-1 sulfuric acid and 6 mol L-1 hydrochloric acid. The extraction with aqua regia showed a clear interconversion of the species during the process, being H2SO4 the best extractant with efficiencies greater than 90% from the total content of Sb and Te quantified previously and without species interconversion. This point was checked by recovery experiments at different spiked levels. The method provided limits of detection values from 0.1 to 0.5 ng g-1 with relative standard deviation values from 5.4 to 9.2% of 10 independent analysis of samples containing few ng g-1 of Sb and Te species. (author)

  5. Determination of cadmium in water samples by fast pyrolysis-chemical vapor generation atomic fluorescence spectrometry

    Science.gov (United States)

    Zhang, Jingya; Fang, Jinliang; Duan, Xuchuan

    2016-08-01

    A pyrolysis-vapor generation procedure to determine cadmium by atomic fluorescence spectrometry has been established. Under fast pyrolysis, cadmium ion can be reduced to volatile cadmium species by sodium formate. The presence of thiourea enhanced the efficiency of cadmium vapor generation and eliminated the interference of copper. The possible mechanism of vapor generation of cadmium was discussed. The optimization of the parameters for pyrolysis-chemical vapor generation, including pyrolysis temperature, amount of sodium formate, concentration of hydrochloric acid, and carrier argon flow rate were carried out. Under the optimized conditions, the absolute and concentration detection limits were 0.38 ng and 2.2 ng ml- 1, respectively, assuming that 0.17 ml of sample was injected. The generation efficiency of was 28-37%. The method was successfully applied to determine trace amounts of cadmium in two certified reference materials of Environmental Water (GSB07-1185-2000 and GSBZ 50009-88). The results were in good agreement with the certified reference values.

  6. Novel Method for Indirect Determination of Iodine in Marine Products by Atomic Fluorescence Spectrometry

    Institute of Scientific and Technical Information of China (English)

    LU Jian-ping; TAN Fang-wei; TANG Qiong; JIANG Tian-cheng

    2013-01-01

    A method for the determination of iodine based upon compound H2HgI4,formed between I-and Hg2+ in nitric acid and extracted in methyl isobutyl ketone(MIBK),was developed via atomic fluorescence spectrometry(AFS).After the compound is reduced with potassium borohydrid(KBH4),the resultant mercury vapor was injected into the instrument and iodine was,therefore,indirectly determined.Experimental parameters such as the conditions of extraction reagents,aqueous phase acidity,elemental mercury diffusion temperature in a vial and other factors were investigated and optimized.Under the optimum experimental conditions,this method shows a detection limit of 0.038 μg/L iodine and a linear relationship between 0.04-20 μg/L.The method was applied to determining the iodine content in marine duck eggs,kelps,laver and Ganoderma lucidum spirulina,showing a relative standard deviation(RSD) of 2.15% and the recoveries in the range of 98.1%-102.5%.

  7. Continuous flow hydride generation-atomic fluorescence spectrometric determination and speciation of arsenic in wine

    International Nuclear Information System (INIS)

    Methods for the atomic fluorescence spectrometric (AFS) determination of total arsenic and arsenic species in wines based on continuous flow hydride generation (HG) with atomization in miniature diffusion flame (MDF) are described. For hydride-forming arsenic, L-cysteine is used as reagent for pre-reduction and complexation of arsenite, arsenate, monomethylarsonate and dimethylarsinate. Concentrations of hydrochloric acid and tetrahydroborate are optimized in order to minimize interference by ethanol. Procedure permits determination of the sum of these four species in 5-10-fold diluted samples with limit of detection (LOD) 0.3 and 0.6 μg l-1 As in white and red wines, respectively, with precision between 2% and 8% RSD at As levels within 0.5-10 μg l-1. Selective arsine generation from different reaction media is used for non-chromatographic determination of arsenic species in wines: citrate buffer at pH 5.1 for As(III); 0.2 mol l-1 acetic acid for arsenite + dimethylarsinate (DMA); 8 mol l-1 HCl for total inorganic arsenic [As(III) + As(V)]; and monomethylarsonate (MMA) calculated by difference. Calibration with aqueous and ethanol-matched standard solutions of As(III) is used for 10- and 5-fold diluted samples, respectively. The LODs are 0.4 μg l-1 for As(III) and 0.3 μg l-1 for the other three As species and precision is within 4-8% RSDs. Arsenic species in wine were also determined by coupling of ion chromatographic separation on an anion exchange column and HG-flame AFS detection. Methods were validated by means of recovery studies and comparative analyses by HG-AFS and electrothermal atomic absorption spectrometry after microwave digestion. The LODs were 0.12, 0.27, 0.15 and 0.13 μg l-1 (as As) and RSDs were 2-6%, 5-9%, 3-7% and 2-5% for As(III), As(V), MMA and DMA arsenic species, respectively. Bottled red and white wines from Bulgaria, Republic of Macedonia and Italy were analyzed by non-chromatographic and chromatographic procedures and the As

  8. Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

    Science.gov (United States)

    Conway, J.; Gogna, G. S.; Gaman, C.; Turner, M. M.; Daniels, S.

    2016-08-01

    Atomic oxygen number density [O] is measured in an air atmospheric pressure plasma jet (APPJ) using two-photon absorption laser induced fluorescence (TALIF). Gas flow is fixed at 8 slpm, the RF power coupled into the plasma jet varied between 5 W and 20 W, and the resulting changes in atomic oxygen density measured. Photolysis of molecular oxygen is employed to allow in situ calibration of the TALIF system. During calibration, O2 photo-dissociation and two-photon excitation of the resulting oxygen atoms are achieved within the same laser pulse. The atomic oxygen density produced by photolysis is time varying and spatially non-uniform which needs to be corrected for to calibrate the TALIF system for measurement of atomic oxygen density in plasma. Knowledge of the laser pulse intensity I 0(t), wavelength, and focal spot size allows correction factors to be determined using a rate equation model. Atomic oxygen is used for calibration and measurement, so the laser intensity can be increased outside the TALIF quadratic laser power dependence region without affecting the calibration reliability as the laser power dependence will still be the same for both. The atomic O density results obtained are not directly benchmarked against other known density measurement techniques. The results show that the plasma jet atomic oxygen content increases as the RF power coupled into the plasma increases.

  9. A Proposed Method for Measurement of Absolute Air Fluorescence Yield based on High Resolution Optical Emission Spectroscopy

    CERN Document Server

    Gika, V; Maltezos, S

    2016-01-01

    In this work, we present a method for absolute measurement of air fluorescence yield based on high resolution optical emission spectroscopy. The absolute measurement of the air fluorescence yield is feasible using the Cherenkov light, emitted by an electron beam simultaneously with the fluorescence light, as a "standard candle". The separation of these two radiations can be accomplished exploiting the "dark" spectral regions of the emission band systems of the molecular spectrum of nitrogen. In these "dark" regions the net Cherenkov light can be recorded experimentally and be compared with the calculated one. The instrumentation for obtaining the nitrogen molecular spectra in high resolution and the noninvasive method for monitoring the rotational temperature of the emission process are also described. For the experimental evaluation of the molecular spectra analysis we used DC normal glow discharges in air performed in an appropriate spectral lamp considered as an air-fluorescence light emulator. The propose...

  10. Comparison of field portable measurements of ultrafine TiO2: X-ray fluorescence, laser-induced breakdown spectroscopy, and Fourier-transform infrared spectroscopy

    OpenAIRE

    LeBouf, Ryan F; Miller, Arthur L.; Stipe, Christopher; Brown, Jonathan; Murphy, Nate; Stefaniak, Aleksandr B

    2013-01-01

    Laboratory measurements of ultrafin0e titanium dioxide (TiO2) particulate matter loaded on filters were made using three field portable methods (X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS), and Fourier-transform infrared (FTIR) spectroscopy) to assess their potential for determining end-of-shift exposure. Ultrafine TiO2 particles were aerosolized and collected onto 37 mm polycarbonate track-etched (PCTE) filters in the range of 3 to 578 µg titanium (Ti). Limit of det...

  11. Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy

    Science.gov (United States)

    Stadnik, Y. V.; Flambaum, V. V.

    2016-08-01

    Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field ϕ =ϕ0cos(mϕt ) , can induce oscillating variations in the fundamental constants through their interactions with the standard model sector. We calculate the effects of such possible interactions, which may include the linear interaction of ϕ with the Higgs boson, on atomic and molecular transitions. Using recent atomic clock spectroscopy measurements, we derive limits on the linear interaction of ϕ with the Higgs boson, as well as its quadratic interactions with the photon and light quarks. For the linear interaction of ϕ with the Higgs boson, our derived limits improve on existing constraints by up to 2-3 orders of magnitude.

  12. Atomic-scale chemical quantification of oxide interfaces using energy-dispersive X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ping; Van Benthem, Mark [Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185-1411 (United States); Xiong, Jie; Jia, Quanxi [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2013-04-29

    Atomic-scale quantification of chemical composition across oxide interfaces is important for understanding physical properties of epitaxial oxide nanostructures. Energy-dispersive X-ray spectroscopy (EDS) in an aberration-corrected scanning transmission electron microscope was used to quantify chemical composition across the interface of ferromagnetic La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and antiferromagnetic BiFeO{sub 3} quantum structure. This research demonstrates that chemical composition at atomic columns can be quantified by Gaussian peak-fitting of EDS compositional profiles across the interface. Cation diffusion was observed at both A- and B-sublattice sites; and asymmetric chemical profiles exist across the interface, consistent with the previous studies.

  13. In-situ measurement of vacuum window birefringence by atomic spectroscopy

    CERN Document Server

    Steffen, Andreas; Genske, Maximilian; Meschede, Dieter; Robens, Carsten; Alberti, Andrea

    2013-01-01

    We present an in-situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly-polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence $\\Delta n$ at the level of $10^{-8}$ and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses.

  14. Atomic physics studies of highly charged ions on tokamaks using x-ray spectroscopy

    International Nuclear Information System (INIS)

    An overview is given of atomic physics issues which have been studied on tokamaks with the help resolution x-ray spectroscopy. The issues include the testing of model calculations predicting the excitation of line radiation, the determination of rate coefficients, and accurate atomic structure measurements. Recent research has focussed primarily on highly charged heliumlike (22 ≤ Z ≤ 28) and neonlike (34 ≤ Z ≤ 63) ions, and results are presented from measurements on the PLT and TFTR tokamaks. Many of the measurements have been aided by improved instrumental design and new measuring techniques. Remarkable agreement has been found between measurements and theory in most cases. However, in this review those areas are stressed where agreement is worst and where further investigations are needed. 19 refs., 13 figs., 2 tabs

  15. Resonant two-photon ionization spectroscopy of Al atoms and dimers solvated in helium nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Krasnokutski, Serge A.; Huisken, Friedrich [Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, D-07743 Jena (Germany)

    2015-02-28

    Resonant two-photon ionization (R2PI) spectroscopy has been applied to investigate the solvation of Al atoms in helium droplets. The R2PI spectra reveal vibrational progressions that can be attributed to Al–He{sub n} vibrations. It is found that small helium droplets have very little chance to pick up an aluminum atom after collision. However, the pick-up probability increases with the size of the helium droplets. The absorption band that is measured by monitoring the ions on the mass of the Al dimer is found to be very little shifted with respect to the Al monomer band (∼400 cm{sup −1}). However, using the same laser wavelength, we were unable to detect any Al{sub n} photoion with n larger than two.

  16. Determination of heavy metals in solid emission and immission samples using atomic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fara, M.; Novak, F. [EGU Prague, PLC, Bichovice, Prague (Czechoslovakia)

    1995-12-01

    Both flame and electrothermal methods of atomic absorption spectroscopy (AAS) have been applied to the determination of Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, TI, Se, V and Zn in emission and emission (deposition) samples decomposed in open PTFE test-tubes by individual fuming-off hydrofluoric, perchloroic and nitric acid. An alternative hydride technique was also used for As and Se determination and Hg was determined using a self-contained AAS analyzer. A graphite platform proved good to overcome non-spectral interferences in AAS-ETA. Methods developed were verified by reference materials (inc. NBS 1633a).

  17. Rotational spectra of N$_2^+$: An advanced undergraduate laboratory in atomic and molecular spectroscopy

    CERN Document Server

    Bayram, S B; Arndt, P T

    2015-01-01

    We describe an inexpensive instructional experiment that demonstrates the rotational energy levels of diatomic nitrogen, using the emission band spectrum of molecular nitrogen ionized by various processes in a commercial AC capillary discharge tube. The simple setup and analytical procedure is introduced as part of a sequence of educational experiments employed by a course of advanced atomic and molecular spectroscopy, where the study of rotational spectra is combined with the analysis of vibrational characteristics for a multifaceted picture of the quantum states of diatomic molecules.

  18. Spectroscopy of cesium Rydberg atoms in strong radio-frequency fields

    CERN Document Server

    Jiao, Yuechun; Li, Jingkui; Raithel, Georg; Zhao, Jianming; Jia, Suotang

    2016-01-01

    We study Rydberg atoms modulated by strong radio-frequency (RF) fields with a frequency of 70 MHz. The Rydberg atoms are prepared in a room temperature cesium cell, and their level structure is probed using electromagnetically induced transparency (EIT). As the RF field increases from the weak- into the strong-field regime, the range of observed RF-induced phenomena progresses from AC level shifts through increasingly pronounced and numerous RF-modulation sidebands to complex state-mixing and level-crossings with high-l hydrogen-like states. Weak anharmonic admixtures in the RF field generate clearly visible modifications in the Rydberg-EIT spectra. A Floquet analysis is employed to model the Rydberg spectra, and good agreement with the experimental observations is found. Our results show that all-optical spectroscopy of Rydberg atoms in vapor cells can serve as an antenna-free, atom-based and calibration-free technique to measure and map RF electric fields and to analyze their higher-harmonic contents.

  19. Light-induced atom desorption from glass surfaces characterized by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Kumagai, Ryo; Hatakeyama, Atsushi

    2016-07-01

    We analyzed the surfaces of vitreous silica (quartz) and borosilicate glass (Pyrex) substrates exposed to rubidium (Rb) vapor by X-ray photoelectron spectroscopy (XPS) to understand the surface conditions of alkali metal vapor cells. XPS spectra indicated that Rb atoms adopted different bonding states in quartz and Pyrex. Furthermore, Rb atoms in quartz remained in the near-surface region, while they diffused into the bulk in Pyrex. For these characterized surfaces, we measured light-induced atom desorption (LIAD) of Rb atoms. Clear differences in time evolution, photon energy dependence, and substrate temperature dependence were found; the decay of LIAD by continuous ultraviolet irradiation for quartz was faster than that for Pyrex, a monotonic increase in LIAD with increasing photon energy from 1.8 to 4.3 eV was more prominent for quartz, and LIAD from quartz was more efficient at higher temperatures in the range from 300 to 580 K, while that from Pyrex was almost independent of temperature.

  20. Quantitative Determination of Arsenic in Bottled Drinking Water Using Atomic Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Maria Guţu Claudia

    2013-10-01

    Full Text Available Background: Many studies have been performed in the past few years, to determine arsenic speciation in drinking water, food chain and environment, arsenic being a well-recognized carcinogenic and toxic agent mainly in its inorganic species. The instrumental techniques used for arsenic determination, such as hydride generation atomic absorption spectrometry (HGAAS, graphite furnace atomic absorption spectrometry (GFAAS and inductively coupled plasma mass spectrometry (ICP-MS, can provide a great sensitivity only on the total amount. Objective: The aim of this study was to develop a simple and rapid method and to analyze the concentration of total inorganic arsenic in bottled drinking water. Methods: Total arsenic was determined in samples from six different types of commercially available bottled drinking water using atomic absorption spectrometry with electrothermal or hydride generation vaporisation. All drinking water samples were acidified with 0.1M nitric acid to match the acidity of the standards. Results: The method was linear within the studied range (1-5 μg/L, R = 0.9943. The quantification limits for arsenic determination were 0.48 μg/L (HGAAS and 0.03 μg/L (GFAAS. The evaluated arsenic content in drinking water was within the accepted limits provided by law. Conclusions: A simple and sensitive method for the quantification of arsenic in drinking water using atomic absorbtion spectroscopy was described, which can be further used in toxicological studies. As an additional advantage, the system is very fast, efficient and environmental friendly

  1. Fluorescence correlation spectroscopy, a tool to investigate supramolecular dynamics: inclusion complexes of pyronines with cyclodextrin.

    Science.gov (United States)

    Al-Soufi, Wajih; Reija, Belén; Novo, Mercedes; Felekyan, Suren; Kühnemuth, Ralf; Seidel, Claus A M

    2005-06-22

    The control of supramolecular systems requires a thorough understanding of their dynamics on a molecular level. We present fluorescence correlation spectroscopy (FCS) as a powerful spectroscopic tool to study supramolecular dynamics with single molecule sensitivity. The formation of a supramolecular complex between beta-cyclodextrin (beta-CD) as host and pyronines Y (PY) and B (PB) as guests is studied by FCS. Global target analysis of full correlation curves with a newly derived theoretical model yields in a single experiment the fluorescence lifetimes and the diffusion coefficients of free and complexed guests and the rate constants describing the complexation dynamics. These data give insight into the recently published surprising fact that the association equilibrium constant of beta-CD with PY is much lower than that with the much bulkier guest PB. FCS shows that the stability of the complexes is dictated by the dissociation and not by the association process. The association rate constants are very similar for both guests and among the highest reported for this type of systems, although much lower than the diffusion-controlled collision rate constant. A two-step model including the formation of an encounter complex allows one to identify the unimolecular inclusion reaction as the rate-limiting step. Simulations indicate that this step may be controlled by geometrical and orientational requirements. These depend on critical molecular dimensions which are only weakly affected by the different alkyl substituents of PY and PB. Diffusion coefficients of PY and PB, of their complexes, and of rhodamine 110 are given and compared to those of similar molecules.

  2. Dopamine Receptor Signaling in MIN6 β-Cells Revealed by Fluorescence Fluctuation Spectroscopy.

    Science.gov (United States)

    Caldwell, Brittany; Ustione, Alessandro; Piston, David W

    2016-08-01

    Insulin secretion defects are central to the development of type II diabetes mellitus. Glucose stimulation of insulin secretion has been extensively studied, but its regulation by other stimuli such as incretins and neurotransmitters is not as well understood. We investigated the mechanisms underlying the inhibition of insulin secretion by dopamine, which is synthesized in pancreatic β-cells from circulating L-dopa. Previous research has shown that this inhibition is mediated primarily by activation of the dopamine receptor D3 subtype (DRD3), even though both DRD2 and DRD3 are expressed in β-cells. To understand this dichotomy, we investigated the dynamic interactions between the dopamine receptor subtypes and their G-proteins using two-color fluorescence fluctuation spectroscopy (FFS) of mouse MIN6 β-cells. We show that proper membrane localization of exogenous G-proteins depends on both the Gβ and Gγ subunits being overexpressed in the cell. Triple transfections of the dopamine receptor subtype and Gβ and Gγ subunits, each labeled with a different-colored fluorescent protein (FP), yielded plasma membrane expression of all three FPs and permitted an FFS evaluation of interactions between the dopamine receptors and the Gβγ complex. Upon dopamine stimulation, we measured a significant decrease in interactions between DRD3 and the Gβγ complex, which is consistent with receptor activation. In contrast, dopamine stimulation did not cause significant changes in the interactions between DRD2 and the Gβγ complex. These results demonstrate that two-color FFS is a powerful tool for measuring dynamic protein interactions in living cells, and show that preferential DRD3 signaling in β-cells occurs at the level of G-protein release. PMID:27508444

  3. Noninvasive fluorescence excitation spectroscopy for the diagnosis of oral neoplasia in vivo

    Science.gov (United States)

    Ebenezar, Jeyasingh; Ganesan, Singaravelu; Aruna, Prakasarao; Muralinaidu, Radhakrishnan; Renganathan, Kannan; Saraswathy, Thillai Rajasekaran

    2012-09-01

    Fluorescence excitation spectroscopy (FES) is an emerging approach to cancer detection. The goal of this pilot study is to evaluate the diagnostic potential of FES technique for the detection and characterization of normal and cancerous oral lesions in vivo. Fluorescence excitation (FE) spectra from oral mucosa were recorded in the spectral range of 340 to 600 nm at 635 nm emission using a fiberoptic probe spectrofluorometer to obtain spectra from the buccal mucosa of 30 sites of 15 healthy volunteers and 15 sites of 10 cancerous patients. Significant FE spectral differences were observed between normal and well differentiated squamous cell carcinoma (WDSCC) oral lesions. The FE spectra of healthy volunteers consists of a broad emission band around 440 to 470 nm, whereas in WDSCC lesions, a new primary peak was seen at 410 nm with secondary peaks observed at 505, 540, and 580 nm due to the accumulation of porphyrins in oral lesions. The FE spectral bands of the WDSCC lesions resemble the typical absorption spectra of a porphyrin. Three potential ratios (I410/I505, I410/I540, and I410/I580) were calculated from the FE spectra and used as input variables for a stepwise linear discriminant analysis (SLDA) for normal and WDSCC groups. Leave-one-out (LOO) method of cross-validation was performed to check the reliability on spectral data for tissue characterization. The diagnostic sensitivity and specificity were determined for normal and WDSCC lesions from the scatter plot of the discriminant function scores. It was observed that diagnostic algorithm based on discriminant function scores obtained by SLDA-LOO method was able to distinguish WDSCC from normal lesions with a sensitivity of 100% and specificity of 100%. Results of the pilot study demonstrate that the FE spectral changes due to porphyrin have a good diagnostic potential; therefore, porphyrin can be used as a native tumor marker.

  4. Spectroscopy of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) attached to rare gas samples: Clusters vs. bulk matrices. II. Fluorescence emission spectroscopy

    OpenAIRE

    Dvorak, Matthieu; Mueller, Markus; Knoblauch, Tobias; Buenermann, Oliver; Rydlo, Alexandre; Minniberger, Stefan; Harbich, Wolfgang; Stienkemeier, Frank

    2012-01-01

    The interaction between 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. Laser-excited PTCDA-doped large argon, neon, and para-hydrogen clusters along with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground state takes place. In co...

  5. Removal of Chromophore-proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor

    Directory of Open Access Journals (Sweden)

    Heli eLehtivuori

    2015-11-01

    Full Text Available Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in native phytochromes, presumably due to the proximity of its backbone carbonyl to the pyrrole ring nitrogens of the biliverdin (BV chromophore as well as the size and charge of the side chain. We hypothesized that the polar interaction network formed by the charged side chain may contribute to the decay of the excited state via proton transfer. Thus, we chose to further probe the role of this amino acid by removing all possibility for polar interactions with its carboxylate side chain by incorporating leucine instead. The resultant fluorescent protein, WiPhy2, maintains BV binding, monomeric status, and long maximum excitation wavelength while minimizing undesirable protoporphyrin IXα binding in cells. A crystal structure and time-resolved fluorescence spectroscopy reveal that water near the BV chromophore is excluded and thus validate our hypothesis that removal of polar interactions leads to enhanced fluorescence by increasing the lifetime of the excited state. This new phytofluor maintains its fluorescent properties over a broad pH range and does not suffer from photobleaching. WiPhy2 achieves the best compromise to date between high fluorescence quantum yield and long illumination wavelength in this class of fluorescent proteins.

  6. Potential of two-line atomic fluorescence for temperature imaging in turbulent indium-oxide-producing flames

    International Nuclear Information System (INIS)

    The applicability of two-line atomic fluorescence (TLAF) for temperature imaging in an indium-based flame spray pyrolysis (FSP) process is demonstrated using a single tunable optical parametric oscillator (OPO) to generate the required excitation wavelengths consecutively. Single-shot images of the detected fluorescence signals demonstrate that the signal levels in the flame are suitable for evaluation of temperature and verify the capability and potential of the measurement technique directly during particle formation without additional indium seeding. Qualitative averaged two-dimensional temperature distributions in the FSP flame are presented, showing the influence of varying sheath gas flow rates on the resulting temperature distribution. With the addition of a second OPO and detection system, the two fluorescence signals acquired consecutively in this work could be obtained simultaneously and enable spatio-temporally resolved single-shot temperature measurements in flame synthesis processes of indium-containing nanoparticles

  7. Potential of two-line atomic fluorescence for temperature imaging in turbulent indium-oxide-producing flames

    Energy Technology Data Exchange (ETDEWEB)

    Münsterjohann, Bettina; Huber, Franz J. T.; Klima, Tobias C.; Holfelder, Sandra; Engel, Sascha R. [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany); Miller, Joseph D. [Aerospace Systems Directorate, Air Force Research Laboratory (United States); Meyer, Terrence R. [Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen Graduate School in Advanced Optical Technologies (SAOT) (Germany); Will, Stefan, E-mail: stefan.will@fau.de [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany)

    2015-11-15

    The applicability of two-line atomic fluorescence (TLAF) for temperature imaging in an indium-based flame spray pyrolysis (FSP) process is demonstrated using a single tunable optical parametric oscillator (OPO) to generate the required excitation wavelengths consecutively. Single-shot images of the detected fluorescence signals demonstrate that the signal levels in the flame are suitable for evaluation of temperature and verify the capability and potential of the measurement technique directly during particle formation without additional indium seeding. Qualitative averaged two-dimensional temperature distributions in the FSP flame are presented, showing the influence of varying sheath gas flow rates on the resulting temperature distribution. With the addition of a second OPO and detection system, the two fluorescence signals acquired consecutively in this work could be obtained simultaneously and enable spatio-temporally resolved single-shot temperature measurements in flame synthesis processes of indium-containing nanoparticles.

  8. Genetic algorithms optimization approach supported by the first-order derivative and Newton-Raphson methods: Application to fluorescence spectroscopy

    Science.gov (United States)

    Fisz, J. J.; Buczkowski, M.; Budziński, M. P.; Kolenderski, P.

    2005-05-01

    The application of genetic algorithms (GA) optimization approach supported by the first-order derivative (FOD) and Newton-Raphson (NR) methods to time-resolved polarized fluorescence spectroscopy, is discussed. It is demonstrated that the application of both methods to χ2 function reduces the number of adjustable model parameters. The combination of GA-optimizer with the FOD and NR methods improves considerably the efficiency of global analysis of kinetic and polarized fluorescence decays for solutions and organized media, including the case of excited-state processes.

  9. Combining atomic force-fluorescence microscopy with a stretching device for analyzing mechanotransduction processes in living cells.

    Science.gov (United States)

    Hecht, E; Knittel, P; Felder, E; Dietl, P; Mizaikoff, B; Kranz, C

    2012-11-21

    Mechanical forces affect biological systems in their natural environment in a widespread manner. Mechanical stress may either stimulate cells or even induce pathological processes. Cells sensing mechanical stress usually respond to such stressors with proliferation or differentiation. Hence, for in vitro studies, the ability to impose a controlled mechanical stress on cells combined with appropriate analytical tools providing an immediate answer is essential to understand such fundamental processes. Here, we present a novel uniaxial motorized cell stretching device that has been integrated into a combined fluorescence microscope (FM)-atomic force microscope (AFM) system, thereby enabling high-resolution topographic and fluorescent live cell imaging. This unique tool allows the investigation of mechanotransduction processes, as the cells may be exposed to deliberately controlled mechanical stress while simultaneously facilitating fluorescence imaging and AFM studies. The developed stretching device allows applying reproducible uniaxial strain from physiologically relevant to hyperphysiological levels to cultured cells grown on elastic polydimethylsiloxane (PDMS) membranes. Exemplarily, stretching experiments are shown for transfected squamous cell carcinoma cells (SCC-25) expressing fluorescent labeled cytokeratin, whereby fluorescence imaging and simultaneously performed AFM measurements reveal the cytokeratin (CSK) network. Topographical changes and mechanical characteristics such as elasticity changes were determined via AFM while the cells were exposed to mechanical stress. By applying a cell deformation of approx. 20%, changes in the Young's modulus of the cytoskeletal network due to stretching of the cells were observed. Consequently, integrating a stretching device into the combined atomic force-fluorescence microscope provides a unique tool for dynamically analyzing structural remodeling and mechanical properties in mechanically stressed cells. PMID:22977882

  10. Atomic force spectroscopy and density-functional study of graphene corrugation on Ru(0001)

    Science.gov (United States)

    Voloshina, Elena; Dedkov, Yuriy

    2016-06-01

    Graphene, the thinnest material in the world, can form moiré structures on different substrates, including graphite, h -BN, or metal surfaces. In such systems, the structure of graphene, i.e., its corrugation, as well as its electronic and elastic properties, are defined by the combination of the system geometry and local interaction strength at the interface. The corrugation in such structures on metals is heavily extracted from diffraction or local probe microscopy experiments, and it can be obtained only via comparison with theoretical data, which usually simulate the experimental findings. Here we show that graphene corrugation on metals can be measured directly employing atomic force spectroscopy, and the obtained value coincides with state-of-the-art theoretical results. The presented results demonstrate an unexpected space selectivity for the Δ f (z ) signal in the atomic force spectroscopy in the moiré graphene lattice on Ru(0001), which is explained by the different response of the graphene layer on the indentation process. We also address the elastic reaction of the formed graphene nanodoms on the indentation process by the scanning tip that is important for the modeling and fabrication of graphene-based nanoresonators on the nanoscale.

  11. Tracking transcription factor mobility and interaction in Arabidopsis roots with fluorescence correlation spectroscopy.

    Science.gov (United States)

    Clark, Natalie M; Hinde, Elizabeth; Winter, Cara M; Fisher, Adam P; Crosti, Giuseppe; Blilou, Ikram; Gratton, Enrico; Benfey, Philip N; Sozzani, Rosangela

    2016-06-11

    To understand complex regulatory processes in multicellular organisms, it is critical to be able to quantitatively analyze protein movement and protein-protein interactions in time and space. During Arabidopsis development, the intercellular movement of SHORTROOT (SHR) and subsequent interaction with its downstream target SCARECROW (SCR) control root patterning and cell fate specification. However, quantitative information about the spatio-temporal dynamics of SHR movement and SHR-SCR interaction is currently unavailable. Here, we quantify parameters including SHR mobility, oligomeric state, and association with SCR using a combination of Fluorescent Correlation Spectroscopy (FCS) techniques. We then incorporate these parameters into a mathematical model of SHR and SCR, which shows that SHR reaches a steady state in minutes, while SCR and the SHR-SCR complex reach a steady-state between 18 and 24 hr. Our model reveals the timing of SHR and SCR dynamics and allows us to understand how protein movement and protein-protein stoichiometry contribute to development.

  12. Effects of multiple scattering on fluorescence correlation spectroscopy measurements of particles moving within optically dense media.

    Science.gov (United States)

    Zustiak, Silviya; Riley, Jason; Boukari, Hacène; Gandjbakhche, Amir; Nossal, Ralph

    2012-12-01

    Fluorescence correlation spectroscopy (FCS) is increasingly being used to assess the movement of particles diffusing in complex, optically dense surroundings, in which case measurement conditions may complicate data interpretation. It is considered how a single-photon FCS measurement can be affected if the sample properties result in scattering of the incident light. FCS autocorrelation functions of Atto 488 dye molecules diffusing in solutions of polystyrene beads are measured, which acted as scatterers. Data indicated that a scattering-linked increase in the illuminated volume, as much as two fold, resulted in minimal increase in diffusivity. To analyze the illuminated beam profile, Monte-Carlo simulations were employed, which indicated a larger broadening of the beam along the axial than the radial directions, and a reduction of the incident intensity at the focal point. The broadening of the volume in the axial direction has only negligible effect on the measured diffusion time, since intensity fluctuations due to diffusion events in the radial direction are dominant in FCS measurements. Collectively, results indicate that multiple scattering does not result in FCS measurement artifacts and thus, when sufficient signal intensity is attainable, single-photon FCS can be a useful technique for measuring probe diffusivity in optically dense media. PMID:23208294

  13. Heat shock-induced interactions among nuclear HSFs detected by fluorescence cross-correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pack, Chan-Gi, E-mail: changipack@amc.seoul.kr [Asan Institute for Life Sciences, University of Ulsan, College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Ahn, Sang-Gun [Dept. of Pathology, College of Dentistry, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of)

    2015-07-31

    The cellular response to stress is primarily controlled in cells via transcriptional activation by heat shock factor 1 (HSF1). HSF1 is well-known to form homotrimers for activation upon heat shock and subsequently bind to target DNAs, such as heat-shock elements, by forming stress granules. A previous study demonstrated that nuclear HSF1 and HSF2 molecules in live cells interacted with target DNAs on the stress granules. However, the process underlying the binding interactions of HSF family in cells upon heat shock remains unclear. This study demonstrate for the first time that the interaction kinetics among nuclear HSF1, HSF2, and HSF4 upon heat shock can be detected directly in live cells using dual color fluorescence cross-correlation spectroscopy (FCCS). FCCS analyses indicated that the binding between HSFs was dramatically changed by heat shock. Interestingly, the recovery kinetics of interaction between HSF1 molecules after heat shock could be represented by changes in the relative interaction amplitude and mobility. - Highlights: • The binding interactions among nuclear HSFs were successfully detected. • The binding kinetics between HSF1s during recovery was quantified. • HSF2 and HSF4 strongly formed hetero-complex, even before heat shock. • Nuclear HSF2 and HSF4 bound to HSF1 only after heat shock.

  14. Cell cycle-dependent mobility of Cdc45 determined in vivo by fluorescence correlation spectroscopy.

    Directory of Open Access Journals (Sweden)

    Ronan Broderick

    Full Text Available Eukaryotic DNA replication is a dynamic process requiring the co-operation of specific replication proteins. We measured the mobility of eGFP-Cdc45 by Fluorescence Correlation Spectroscopy (FCS in vivo in asynchronous cells and in cells synchronized at the G1/S transition and during S phase. Our data show that eGFP-Cdc45 mobility is faster in G1/S transition compared to S phase suggesting that Cdc45 is part of larger protein complex formed in S phase. Furthermore, the size of complexes containing Cdc45 was estimated in asynchronous, G1/S and S phase-synchronized cells using gel filtration chromatography; these findings complemented the in vivo FCS data. Analysis of the mobility of eGFP-Cdc45 and the size of complexes containing Cdc45 and eGFP-Cdc45 after UVC-mediated DNA damage revealed no significant changes in diffusion rates and complex sizes using FCS and gel filtration chromatography analyses. This suggests that after UV-damage, Cdc45 is still present in a large multi-protein complex and that its mobility within living cells is consistently similar following UVC-mediated DNA damage.

  15. X-ray fluorescence spectroscopy and Monte Carlo characterization of a unique nuragic artifact (Sardinia, Italy)

    Science.gov (United States)

    Brunetti, Antonio; Depalmas, Anna; di Gennaro, Francesco; Serges, Alessandra; Schiavon, Nicola

    2016-07-01

    The chemical composition of a unique bronze artifact known as the "Cesta" ("Basket") belonging to the ancient Nuragic civilization of the Island of Sardinia, Italy has been analyzed by combining X-ray Fluorescence Spectroscopy (XRF) with Monte Carlo simulations using the XRMC code. The "Cesta" had been discovered probably in the XVIII century with the first graphic representation reported around 1761. In a later draft (dated 1764), the basket has been depicted as being carried upside-down on the shoulder of a large bronze warrior Barthélemy (1761), Pinza (1901), Winckelmann (1776) . The two pictorial representations differed only by the presence of handles in the most recent one. XRF measurements revealed that the handles of the object are composed by brass while the other parts are composed by bronze suggesting the handles as being a later addition to the original object. The artifact is covered at its surface by a fairly thick corrosion patina. In order to determine the bronze bulk composition without the need for removing the outer patina, the artifact has been modeled as a two layer object in Monte Carlo simulations.

  16. Using fluorescence correlation spectroscopy to study diffusion in the presence of a hierarchy of membrane domains

    Science.gov (United States)

    Kalay, Ziya

    2014-03-01

    Fluorescence correlation spectroscopy (FCS) is a commonly used experimental technique to study molecular transport, especially in biological systems. FCS is particularly useful in two-dimensional systems such as the cell membrane, where molecules approximately move in a plane over several hundreds of nanometers, and the signal to noise ratio is high. Recent observations showed that proteins and lipids in the plasma membrane (the outermost membrane of a cell) can become temporarily confined in a hierarchy of membrane domains, induced by actin filaments and dynamic clusters formed by lipids and proteins (rafts). There has been considerable interest in measuring the characteristic size and lifetime of these domains via microscopy techniques, including FCS. Even though FCS is widely applicable, interpretation of the results is often indirect, as data has to be fit to model predictions in order to extract transport coefficients. In this talk, I will present our recent theoretical and computational findings on how FCS measurements would reflect diffusion in the simultaneous presence of cytoskeleton induced membrane compartments, and raft-like domains.

  17. X-ray Fluorescence Spectroscopy Study of Coating Thickness and Base Metal Composition

    Science.gov (United States)

    Rolin, T. D.; Leszczuk, Y.

    2008-01-01

    For electrical, electronic, and electromechanical (EEE) parts to be approved for space use, they must be able to meet safety standards approved by NASA. A fast, reliable, and precise method is needed to make sure these standards are met. Many EEE parts are coated in gold (Au) and nickel (Ni), and the thickness coating is crucial to a part s performance. A nondestructive method that is efficient in measuring coating thickness is x-ray fluorescence (XRF) spectroscopy. The XRF spectrometer is a machine designed to measure layer thickness and composition of single or multilayered samples. By understanding the limitations in the collection of the data by this method, accurate composition and thickness measurements can be obtained for samples with Au and Ni coatings. To understand the limitations of data found, measurements were taken with the XRF spectrometer and compared to true values of standard reference materials (SRM) that were National Institute of Standards and Technology (NIST) traceable. For every sample, six different parameters were varied to understand measurement error: coating/substrate combination, number of layers, counting interval, collimator size, coating thickness, and test area location. Each measurement was taken in accordance with standards set by the American Society for Testing and Materials (ASTM) International Standard B 568.

  18. Tracking transcription factor mobility and interaction in Arabidopsis roots with fluorescence correlation spectroscopy.

    Science.gov (United States)

    Clark, Natalie M; Hinde, Elizabeth; Winter, Cara M; Fisher, Adam P; Crosti, Giuseppe; Blilou, Ikram; Gratton, Enrico; Benfey, Philip N; Sozzani, Rosangela

    2016-01-01

    To understand complex regulatory processes in multicellular organisms, it is critical to be able to quantitatively analyze protein movement and protein-protein interactions in time and space. During Arabidopsis development, the intercellular movement of SHORTROOT (SHR) and subsequent interaction with its downstream target SCARECROW (SCR) control root patterning and cell fate specification. However, quantitative information about the spatio-temporal dynamics of SHR movement and SHR-SCR interaction is currently unavailable. Here, we quantify parameters including SHR mobility, oligomeric state, and association with SCR using a combination of Fluorescent Correlation Spectroscopy (FCS) techniques. We then incorporate these parameters into a mathematical model of SHR and SCR, which shows that SHR reaches a steady state in minutes, while SCR and the SHR-SCR complex reach a steady-state between 18 and 24 hr. Our model reveals the timing of SHR and SCR dynamics and allows us to understand how protein movement and protein-protein stoichiometry contribute to development. PMID:27288545

  19. Lasing dynamics study by femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy

    Science.gov (United States)

    Wei, Dang; Qing, Liao; Peng-Cheng, Mao; Hong-Bing, Fu; Yu-Xiang, Weng

    2016-05-01

    Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy (FNOPAS) is a versatile technique with advantages of high sensitivity, broad detection bandwidth, and intrinsic spectrum correction function. These advantages should benefit the study of coherent emission, such as measurement of lasing dynamics. In this letter, the FNOPAS was used to trace the lasing process in Rhodamine 6G (R6G) solution and organic semiconductor nano-wires. High-quality transient emission spectra and lasing dynamic traces were acquired, which demonstrates the applicability of FNOPAS in the study of lasing dynamics. Our work extends the application scope of the FNOPAS technique. Project supported by the National Natural Science Foundation of China (Grant Nos. 20925313 and 21503066), the Innovation Program of Chinese Academy of Sciences (Grant No. KJCX2-YW-W25), the Postdoctoral Project of Hebei University, China, and the Project of Science and Technology Bureau of Baoding City, China (Grant No. 15ZG029).

  20. Mapping Liquid-liquid protein phase separation using ultra-fast-scanning fluorescence correlation spectroscopy

    Science.gov (United States)

    Wei, Ming-Tzo; Elbaum-Garfinkle, Shana; Arnold, Craig B.; Priestley, Rodney D.; Brangwynne, Clifford P.

    Intrinsically disordered proteins (IDPs) are an understudied class of proteins that play important roles in a wide variety of biological processes in cells. We've previously shown that the C. elegans IDP LAF-1 phase separates into P granule-like droplets in vitro. However, the physics of the condensed phase remains poorly understood. Here, we use a novel technique, ultra-fast-scanning fluorescence correlation spectroscopy, to study the nano-scale rheological properties of LAF-1 droplets. Ultra-fast-scanning FCS uses a tunable acoustic gradient index of refraction (TAG) lens with an oil immersion objective to control axial movement of the focal point over a length of several micrometers at frequencies of 70kHz. Using ultra-fast-scanning FCS allows for the accurate determination of molecular concentrations and their diffusion coefficient, when the particle is passing through an excitation volume. Our work reveals an asymmetric LAF-1 phase diagram, and demonstrates that LAF-1 droplets are purely viscous phases which are highly tunable by salt concentration.

  1. Tar analysis from biomass gasification by means of online fluorescence spectroscopy

    Science.gov (United States)

    Baumhakl, Christoph; Karellas, Sotirios

    2011-07-01

    Optical methods in gas analysis are very valuable mainly due to their non-intrusive character. That gives the possibility to use them for in-situ or online measurements with only optical intervention in the measurement volume. In processes like the gasification of biomass, it is of high importance to monitor the gas quality in order to use the product gas in proper machines for energy production following the restrictions in the gas composition but also improving its quality, which leads to high efficient systems. One of the main problems in the biomass gasification process is the formation of tars. These higher hydrocarbons can lead to problems in the operation of the energy system. Up to date, the state of the art method used widely for the determination of tars is a standardized offline measurement system, the so-called "Tar Protocol". The aim of this work is to describe an innovative, online, optical method for determining the tar content of the product gas by means of fluorescence spectroscopy. This method uses optical sources and detectors that can be found in the market at low cost and therefore it is very attractive, especially for industrial applications where cost efficiency followed by medium to high precision are of high importance.

  2. Characterization of the Ã(1A″) state of HCF by laser induced fluorescence spectroscopy

    Science.gov (United States)

    Schmidt, Timothy W.; Bacskay, George B.; Kable, Scott H.

    1999-06-01

    An extensive experimental exploration of the Ã(1A″)←X˜(1A') transition of supersonically cooled fluoromethylene has been performed using laser induced fluorescence spectroscopy. Several new bending vibrational bands are reported, which provide the harmonic frequency and anharmonicity constant for this vibration and lead to an estimate of the height of the barrier to linearity as 6400±500 cm-1. Assignment of the vibrational hot-band structure leads to the first measurement of the à state CF stretching frequency as ν3'=1260 cm-1 and tentatively the CH stretching frequency as ν1'=2852 cm-1. The A' rotational constant increases strongly with increasing quanta of bending vibration, which indicates that the molecular structure is becoming more linear. Consideration of only the average bond angle, calculated from ab initio data for this state, is insufficient to account for the change in A'. The coupling of a-axis rotation with bending vibration must be included. A number of other dynamical effects were observed in the spectra, including lifetime shortening and disappearance of rotational transitions with K'⩾1. These were explained in terms of the Renner-Teller interaction between the X˜ and à states.

  3. Kinetic theory and atomic physics corrections for determination of ion velocities from charge-exchange spectroscopy

    Science.gov (United States)

    Muñoz Burgos, J. M.; Burrell, K. H.; Solomon, W. M.; Grierson, B. A.; Loch, S. D.; Ballance, C. P.; Chrystal, C.

    2013-09-01

    Charge-exchange spectroscopy is a powerful diagnostic tool for determining ion temperatures, densities and rotational velocities in tokamak plasmas. This technique depends on detailed understanding of the atomic physics processes that affect the measured apparent velocities with respect to the true ion rotational velocities. These atomic effects are mainly due to energy dependence of the charge-exchange cross-sections, and in the case of poloidal velocities, due to gyro-motion of the ion during the finite lifetime of the excited states. Accurate lifetimes are necessary for correct interpretation of measured poloidal velocities, specially for high density plasma regimes on machines such as ITER, where l-mixing effects must be taken into account. In this work, a full nl-resolved atomic collisional radiative model coupled with a full kinetic calculation that includes the effects of electric and magnetic fields on the ion gyro-motion is presented for the first time. The model directly calculates from atomic physics first principles the excited state lifetimes that are necessary to evaluate the gyro-orbit effects. It is shown that even for low density plasmas where l-mixing effects are unimportant and coronal conditions can be assumed, the nl-resolved model is necessary for an accurate description of the gyro-motion effects to determine poloidal velocities. This solution shows good agreement when compared to three QH-mode shots on DIII-D, which contain a wide range of toroidal velocities and high ion temperatures where greater atomic corrections are needed. The velocities obtained from the model are compared to experimental velocities determined from co- and counter-injection of neutral beams on DIII-D.

  4. Atom location using scanning transmission electron microscopy based on electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Full text: The technique of atom location by channelling enhanced microanalysis (ALCHEMI) using cross section data, measured as a function of electron beam orientation, has been widely implemented by many researchers. The accurate application of ALCHEMI, usually based on energy dispersive x-ray analysis (EDX), requires knowledge, from first principles, of the relative delocalization of the inner-shell ionization interaction (see for example Oxley and Allen, 1998; Oxley et al., 1999). Scanning transmission electron microscopy (STEM) based on electron energy loss spectroscopy (EELS) also provides information about the location of atoms of different types within the crystal lattice. Unlike high angle annular dark field (HAADF), EELS provides a unique signal for each atom type. In conjunction with highly focused probes, allowing near atomic resolution, this makes possible, in principle, the application of ALCHEMI like techniques to STEM images to determine the distribution of impurities within the unit cell. The accurate interpretation of STEM results requires that both the inner-shell ionization interaction and resulting ionization cross section or image be correctly modelled. We present model calculations demonstrating the in principle application of ALCHEMI type techniques to STEM images pertinent to EELS. The inner-shell ionisation interaction is modelled using Hartree-Fock wave functions to describe the atomic bound states and Hartree-Slater wave functions to describe the continuum states. The wave function within the crystal is calculated using boundary conditions appropriate for a highly focussed probe (Rossouw and Allen, 2001) and STEM images or ionisation cross sections are simulated using an inelastic cross section formulation that correctly accounts for the contribution from both dynamical electrons and those dechannelled by absorptive scattering processes such as thermal diffuse scattering (TDS). Copyright (2002) Australian Society for Electron Microscopy

  5. Study of the Neutron Deficient Pb and Bi Isotopes by Simultaneous Atomic- and Nuclear-Spectroscopy

    CERN Multimedia

    Kessler, T

    2002-01-01

    We propose to study systematically nuclear properties of the neutron deficient lead $^{183-189}$Pb, $^{191g}$Pb, $^{193g}$Pb and bismuth isotopes $^{188-200}$Bi by atomic spectroscopy with the ISOLDE resonance ionisation laser ion source (RILIS) combined with simultaneous nuclear spectroscopy at the detection set-up. The main focus is the determination of the mean square charge radii of $^{183-190}$Pb and $^{188-193}$Bi from which the influence of low-lying intruder states should become obvious. Also the nuclear spin and magnetic moments of ground-states and long-lived isomers will be determined unambiguously through evaluation of the hyperfine structure, and new isomers could be discovered. The decay properties of these nuclei can be measured by $\\alpha$-$\\gamma$ and $\\beta$-$\\gamma$ spectroscopy. With this data at hand, possible shape transitions around mid-shell at N$\\sim$104 will be studied. This data is crucial for the direct test of nuclear theory in the context of intruder state influence (e.g. energy ...

  6. Precision X-ray spectroscopy of kaonic atoms as a probe of low-energy kaon-nucleus interaction

    CERN Document Server

    Shi, H; Beer, G; Bellotti, G; Berucci, C; Bragadireanu, A M; Bosnar, D; Cargnelli, M; Curceanu, C; Butt, A D; d'Uffizi, A; Fiorini, C; Ghio, F; Guaraldo, C; Hayano, R S; Iliescu, M; Ishiwatari, T; Iwasaki, M; Sandri, P Levi; Marton, J; Okada, S; Pietreanu, D; Piscicchia, K; Vidal, A Romero; Sbardella, E; Scordo, A; Sirghi, D L; Sirghi, F; Tatsuno, H; Doce, O Vazquez; Widmann, E; Zmeskal, J

    2016-01-01

    In the exotic atoms where one atomic $1s$ electron is replaced by a $K^{-}$, the strong interaction between the $K^{-}$ and the nucleus introduces an energy shift and broadening of the low-lying kaonic atomic levels which are determined by only the electromagnetic interaction. By performing X-ray spectroscopy for Z=1,2 kaonic atoms, the SIDDHARTA experiment determined with high precision the shift and width for the $1s$ state of $K^{-}p$ and the $2p$ state of kaonic helium-3 and kaonic helium-4. These results provided unique information of the kaon-nucleus interaction in the low energy limit.

  7. Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy.

    Science.gov (United States)

    Haruta, Mitsutaka; Hosaka, Yoshiteru; Ichikawa, Noriya; Saito, Takashi; Shimakawa, Yuichi; Kurata, Hiroki

    2016-07-26

    Atomic-resolution quantification of the elemental ratio of Fe to Mn at the octahedral and tetrahedral sites in brownmillerite Ca2Fe1.07Mn0.93O5 was determined using electron energy-loss spectroscopy combined with aberration-corrected scanning transmission electron microscopy. The combined techniques revealed that oversampling of the spectral imaging data yielded a spatially resolved area that very nearly reflects atomic resolution (∼1.2 Å radius). The average experimental ratios of Fe to Mn within this region were 17.5:82.5 for the octahedral sites and 81.6:18.4 for the tetrahedral sites. The elemental ratio in an octahedral atomic column was successfully extracted by estimating the mixing of signals from nearest neighbor columns. The results indicated that the ratio of Fe to Mn was 13:87 at the octahedral site, which is in good agreement with the results of neutron diffraction analysis. In addition, the uncertainty of experimental results obtained by using an average 1.2 Å radius was less than 10% at octahedral sites, depending on the sample thickness. In contrast, the experimental error due to dechanneling of incident electrons was larger at the tetrahedral sites. This experimental procedure has wide application for determining the spatially resolved composition ratio of elements in perovskite-like compounds. PMID:27341006

  8. Evaluation on corrosively dissolved gold induced by alkanethiol monolayer with atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    We have monitored a gold corrosive dissolution behavior accompanied in n-alkanethiol like n-dodecanethiol assembled process with in situ quartz crystal microbalance (QCM), and then observed it with atomic force microscopy (AFM) which showed an evident image of corrosive defects or holes produced on gold substrate, corresponding to gold dissolution induced by the alkanethiol molecules in the presence of oxygen. For detection of the dissolved gold defects during alkanethiol assembled process, an atomic absorption spectroscopy (AAS) has been carried out in this paper, and the detection limit for the dissolved gold could be evaluated to be 15.4 ng/mL. The amount of dissolved gold from the substrates of gold plates as functions of immersion time, acid media, solvents and thiol concentration has been examined in the oxygen saturated solutions. In comparison with in situ QCM method, the kinetics behavior of the long-term gold corrosion on the gold plates in 1.0 mmol/L of n-dodecanethiol solution determined with AAS method was a slow process, and its corrosion rate on gold dissolution could be evaluated to be about 4.4 x 10-5 ng.cm-2.s-1, corresponding to 1.3 x 108 Au atoms.cm-2.s-1, that was much smaller than that of initial rate monitored with in situ QCM. Both kinetics equations obtained with QCM and AAS showed a consistent corrosion behavior on gold surfaces.

  9. Effect of ethanol-water mixture on the structure and dynamics of lysozyme: A fluorescence correlation spectroscopy study

    Science.gov (United States)

    Chattoraj, Shyamtanu; Mandal, Amit Kumar; Bhattacharyya, Kankan

    2014-03-01

    Effect of ethanol-water mixture on the hydrodynamic radius (rH) and conformational dynamics of lysozyme has been studied by circular dichroism, emission spectra, and fluorescence correlation spectroscopy. For this purpose, the protein lysozyme is covalently labeled near the active site with a fluorescent probe, alexa 488. The ethanol molecules are sequestered near the hydrophobic tryptophan residues as indicated by the blue shift of the emission maximum of tryptophan. It is observed that both size (rH) and time constant of conformational relaxation (τR) of lysozyme oscillate with increase in ethanol concentration. The rH of the protein fluctuates from 19 Å in the native state, to a minimum of 13 Å, and a maximum of 29 Å. It is proposed that the oscillating behavior arises from competition between mutual interaction among protein, ethanol, and water. The fluorescence intensity fluctuates because of quenching of the fluorescence of the probe (alexa) by the free amino group of certain residues (e.g., tryptophan). Rate of inter-conversion (folding dynamics) between the open (fluorescent) and closed (non-fluorescent) form has been determined and is found to exhibit similar oscillation with variation in ethanol content.

  10. A Nanoplasmonic Strategy for Precision in-situ Measurements of Tip-enhanced Raman and Fluorescence Spectroscopy

    Science.gov (United States)

    Meng, Lingyan; Sun, Mengtao; Chen, Jianing; Yang, Zhilin

    2016-01-01

    We theoretically investigate an optimized tip-film system that supports in-situ measurement of tip-enhanced Raman spectroscopy (TERS) and tip-enhanced fluorescence (TEF) of dye molecules. A scanning tunneling microscope (STM) is proposed to precisely control the tip-film distance, and thus in-situ measurement of TERS and TEF can be realized utilizing the specific surface plasmon resonance (SPR) properties of the tip-film system. Our calculations show that the optimized tip-film distance of 2 nm suggests a possibility of efficient acquisition of TERS and TEF in-situ. The calculated spatial resolution of TERS and spectral resolution of TEF can be down to 6.5 nm and 10 nm, respectively. Our theoretical results may find promising application in developing multiple functional nano-spectroscopy through which Raman and fluorescence can be measured in-situ at the nanoscale level.

  11. Mechanisms of ultrafast fluorescence depletion spectroscopy and applications to measure slovation dynamics of coummarin 153 in methanol

    Energy Technology Data Exchange (ETDEWEB)

    Yang Songqiu, E-mail: sqyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Liu Jianyong, E-mail: beam@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Zhou Panwang, E-mail: pwzhou@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Chen Junsheng, E-mail: junshengchen@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Han Keli, E-mail: klhan@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); He Guozhong, E-mail: gzhe@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2012-09-15

    Subpicosecond fluorescence depletion spectroscopy (FDS) was used to measure the solvation dynamics of coumarin 153 (C153) in methanol. The FDS mechanisms were discussed. A quasi-continuous model was used to describe the solvational relaxation of excited states. The perturbations of the probe pulse on the excited sample system, including up-conversion and stimulated emission, were sufficiently discussed. For a probe molecule used in the FDS experiment, ensuring that the up-conversion perturbation can be negligible is important. FDS was found to be a good technique for measuring the solvation dynamics of C153 in methanol. - Highlights: Black-Right-Pointing-Pointer Mechanisms of subpicosecond fluorescence depletion spectroscopy. Black-Right-Pointing-Pointer Quasi-continuous model was used to describe the solvational relaxation. Black-Right-Pointing-Pointer The solvation dynamics of coumarin 153 in methanol has been measured.

  12. Interaction of fisetin with human serum albumin by fluorescence, circular dichroism spectroscopy and DFT calculations: binding parameters and conformational changes

    Energy Technology Data Exchange (ETDEWEB)

    Matei, Iulia; Ionescu, Sorana [Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest (Romania); Hillebrand, Mihaela, E-mail: mihh@gw-chimie.math.unibuc.ro [Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest (Romania)

    2011-08-15

    The interaction between fisetin, an antioxidant and neuroprotective flavonoid, and human serum albumin (HSA) is investigated by means of fluorescence (steady-state, synchronous, time-resolved) and circular dichroism (CD) spectroscopy. The formation of a 1:1 complex with a constant of about 10{sup 5} M{sup -1} was evidenced. Foerster's resonance energy transfer and competitive binding with site markers warfarin and ibuprofen were considered and discussed. Changes in the CD band of HSA indicate a decrease in the {alpha}-helix content upon binding. An induced CD signal for bound fisetin was observed and rationalized in terms of density functional theory calculations. - Highlights: > Fisetin-BSA system was studied by fluorescence spectroscopy. > Binding parameters, association constant and number of sites were estimated. > Binding site of fisetin was identified by competitive experiments. > Conformational changes in HSA and fisetin were evidenced by circular dichroism. > TDDFT calculated CD spectra supported the experimental data.

  13. Highly uniform holographic microtrap arrays for single atom trapping using a feedback optimization of in-trap fluorescence measurements.

    Science.gov (United States)

    Tamura, Hikaru; Unakami, Tomoyuki; He, Jun; Miyamoto, Yoko; Nakagawa, Ken'ichi

    2016-04-18

    We report on the novel optimization method to realize highly uniform microtrap arrays for single atom trapping with a spatial light modulator (SLM). This method consists of two iterative feedback loops with the measurements of both diffracted light intensities and in-trap fluorescence intensities from each microtrap. By applying this method to the single 87Rb atom trapping, we can reduce the variance of trap depths from 20.8% to 1.7% for 4 × 4 square arrays and less than 4% for various arrays with up to 62 sites. The detection error of individual single atoms is also reduced from 1.7% to 0.0054% on average. PMID:27137252

  14. Collective resonance fluorescence in small and dense atom clouds: Comparison between theory and experiment

    CERN Document Server

    Jenkins, S D; Javanainen, J; Jennewein, S; Bourgain, R; Pellegrino, J; Sortais, Y R P; Browaeys, A

    2016-01-01

    We study the emergence of a collective optical response of a cold and dense $^{87}$Rb atomic cloud to a near-resonant low-intensity light when the atom number is gradually increased. Experimental observations are compared with microscopic stochastic simulations of recurrent scattering processes between the atoms that incorporate the atomic multilevel structure and the optical measurement setup. We analyze the optical response of an inhomogeneously-broadened gas and find that the experimental observations of the resonance line shifts and the total collected scattered light intensity in cold atom clouds substantially deviate from those of thermal atomic ensembles, indicating strong light-induced resonant dipole-dipole interactions between the atoms. At high densities, the simulations also predict a significantly slower decay of light-induced excitations in cold than in thermal atom clouds. The role of dipole-dipole interactions is discussed in terms of resonant coupling examples and the collective radiative exc...

  15. Development of fiber optic spectroscopy for in-vitro and in-planta detection of fluorescent proteins

    Science.gov (United States)

    Liew, Oi Wah; Chen, Jun-Wei; Asundi, Anand K.

    2001-10-01

    The objective of this project is to apply photonics technology to bio-safety management of genetically modified (GM) plants. The conventional method for screening GM plants is through selection using antibiotic resistance markers. There is public concern with such approaches and these are associated with food safety issues, escape of antibiotic resistance genes to pathogenic microorganisms and interference with antibiotic therapy. Thus, the strategy taken in this project is to replace antibiotic resistance markers with fluorescent protein markers that allow for rapid and non-invasive optical screening of genetically modified plants. In this paper, fibre optic spectroscopy was developed to detect and quantify recombinant green (EGFP) and red (DsRED) fluorescent proteins in vitro and in planta. In vitro detection was first carried out to optimize the sensitivity of the optical system. The bacterial expression vectors carrying the coding regions of EGFP and DsRED were introduced into Escherichia coli host cells and fluorescent proteins were produced following induction with IPTG. Soluble EGFP and DsRED proteins were isolated from lysed bacterial cells and serially diluted for quantitative analysis by fibre optic spectroscopy using different light sources, namely, blue LED (475 nm), tungsten halogen (350 - 1000 nm) and double frequency Nd:YAG green laser (532 nm). Fluorescence near the expected emission wavelengths could be detected up to 320X dilution for EGFP and DsRED with blue LED and 532 nm green laser, respectively, as the excitation source. Tungsten halogen was found to be unsuitable for excitation of both EGFP and DsRED. EGFP was successfully purified by size separation under non-denaturing electrophoretic conditions and quantified. The minimum concentration of EGFP detectable with blue LED excitation was 5 mg/ml. To determine the capability of spectroscopy detection in planta, transgenic potato hairy roots and whole modified plant lines expressing the

  16. Temporal changes of lysosome and phagosome pH during phagolysosome formation in macrophages: studies by fluorescence spectroscopy

    OpenAIRE

    1981-01-01

    Intravascular pH was measured within the lysosomes and newly formed phagosomes in cultured mouse peritoneal macrophages. The kinetics of pH change in both vacuolar systems was quantitatively determined within a large cell population by fluorescence spectroscopy. Additionally, pH changes within individual phagosomes were followed semiquantitatively using indicator dyes. Two novel findings were made. Firstly, the pH in new phagosomes was transiently driven alkaline (higher than physiological) e...

  17. A versatile dual spot laser scanning confocal microscopy system for advanced fluorescence correlation spectroscopy analysis in living cell

    CERN Document Server

    Ferrand, P; Kress, A; Aillaud, A; Rigneault, H; Marguet, D

    2009-01-01

    A fluorescence correlation spectroscopy (FCS) system based on two independent measurement volumes is presented. The optical setup and data acquisition hardware are detailed, as well as a complete protocol to control the location, size and shape of the measurement volumes. A method that allows to monitor independently the excitation and collection efficiency distribution is proposed. Finally, a few examples of measurements that exploit the two spots in static and/or scanning schemes, are reported.

  18. Speciation of bioaccumulated uranium(VI) by Euglena mutabilis cells obtained by laser fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Brockmann, Sina; Bernhard, Gert [Technical Univ. Dresden (Germany). Radiochemistry; Helmholtz-Zentrum Dresden-Rossendorf (HZDR) e.V., Dresden (Germany). Inst. of Resource Ecology; Arnold, Thuro [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) e.V., Dresden (Germany). Inst. of Resource Ecology

    2014-07-01

    The ability of Euglena mutabilis cells - a unicellular protozoan with a flexible pellicle, which is typically found in acid mine drainage (AMD) environments - to bioaccumulate uranium under acid conditions was studied in batch sorption experiments at pH 3 and 4 using Na{sub 2}SO{sub 4} and NaClO{sub 4} as background media. It was found that axenic cultures of Euglena mutabilis Schmitz were able to bioaccumulate in 5 days 94.9 to 99.2% of uranium from a 1 x 10{sup -5} mol/L uranium solution in perchlorate medium and 95.1 to 95.9% in sodium sulfate medium, respectively. The speciation of uranium in solution and uranium bioaccumulated by Euglena mutabilis cells, were studied by laser induced fluorescence spectroscopy (LIFS). The LIFS investigations showed that the uranium speciation in the NaClO{sub 4} systems was dominated by free uranyl(VI) species and that the UO{sub 2}SO{sub 4} species was dominating in the Na{sub 2}SO{sub 4} medium. Fluorescence spectra of the bioaccumulated uranium revealed that aqueous uranium binds to carboxylic and/or (organo)phosphate groups located on the euglenid pellicle or inside the Euglena mutabilis cells. Reduced uranium immobilization rates of 0.93-1.43 mg uranium per g Euglena mutabilis biomass were observed in similar experiments, using sterile filtrated AMD waters containing, 4.4 x 10{sup -5} mol/L uranium. These lower rates were attributed to competition with other cations for available sorption sites. Additional LIFS measurements, however, showed that the speciation of the bioaccumulated uranium by the Euglena mutabilis cells was found to be identical with the uranium speciation found in the bioaccumulation experiments carried out in Na{sub 2}SO{sub 4} and NaClO{sub 4} media. The results indicate that Euglena mutabilis has the potential to immobilize aqueous uranium under acid condition and thus may be used in future as promising agent for immobilizing uranium in low pH waste water environments. (orig.)

  19. Delta-ALA-mediated fluorescence spectroscopy of gastrointestinal tumors: comparison of in vivo and in vitro results

    Science.gov (United States)

    Vladimirov, B.; Borisova, E.; Avramov, L.

    2007-06-01

    The limitations of standard endoscopy for detection of dysplastic changes of mucosa are significant challenge and initiate development of new photodiagnostic techniques, additional to diagnostic possibilities of standard endoscopic equipment. One of the most widely examined optical modalities is the laser- or light-induced fluorescence spectroscopy (LIFS), because of its rapid and highly sensitive response to early biochemical and morphological changes in biological tissues. In the recent study delta-aminolevulinic acid/protoporphyrin IX is used as fluorescent marker for dysplasia and tumor detection in esophagus and stomach. The δ -ALA is administered per os six hours before measurements at dose 20mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built to use the light guide of standard video-endoscopic system. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. The fluorescence detected from in vivo tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Mucosa autofluorescence lies at 450-600 nm region. The fluorescence of PpIX is clearly pronounced at the 630-710 nm region. Deep minima in the tumor fluorescence signals are observed in the region 540-575 nm, related to hemoglobin re-absorption. Such high hemoglobin content is an indication of the tumors vascularization and it is clearly pronounced in all dysplastic and tumor sites investigated. After formalin conservation for in vitro samples hemoglobin absorption is strongly reduced that increases mucous fluorescence signal in green-yellow spectral region. Simultaneously the maxima at 635 nm and 720 nm are reduced.

  20. Measurements of IO in the Tropical Marine Boundary Layer using Laser-Induced Fluorescence Spectroscopy

    Science.gov (United States)

    Walker, H.; Ingham, T.; Heard, D. E.

    2012-12-01

    Halogenated short-lived substances (VSLS) are emitted from the oceans by marine species such as macroalgae and phytoplankton and contribute to halogen loading in the troposphere and lower stratosphere. Transport of halogenated VSLS into the stratosphere occurs mainly in the tropics, where ascending warm air carries them aloft, and leads to catalytic depletion of stratospheric ozone on a global scale and formation of the Antarctic ozone hole. The tropical marine environment is therefore an important region in which to study the effects of these short-lived halogen species on ozone depletion. The SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project combines ship-borne, aircraft-based and ground-based measurements in and over the South China Sea and the Sulu Sea, and around the coast of Malaysian Borneo, to reduce uncertainties in the amount of halogenated VSLS reaching the stratosphere, the associated ozone depletion, and the effects of a changing climate on these processes. In this work we present measurements of IO radicals made onboard the German research vessel Sonne during SHIVA, between Singapore and Manila. IO is formed via photolysis of iodine-containing source gases (e.g. I2, CH3I) to produce I atoms, which react with ozone. It is therefore an important species to consider when assessing the impacts of halogen chemistry on ozone depletion. Measurements of IO were made over a two-week period by the University of Leeds Laser-Induced Fluorescence (LIF) instrument, which excites IO radicals at λ ~ 445 nm and detects the resultant fluorescence at λ ~ 512 nm. A suite of supporting gas- and aqueous-phase measurements were also made, including concentrations of halocarbons (e.g. CHBr3, CH3I), trace pollutant gases (e.g. CO, O3, NOx), and biological parameters (e.g. abundance and speciation of phytoplankton). Preliminary data analysis indicates that IO was detected above the instrumental limit of detection (0.3 pptv for a 30 minute averaging

  1. Nuclear structure of light thallium isotopes as deduced from laser spectroscopy on a fast atom beam

    International Nuclear Information System (INIS)

    After optimizing the system by experiments on /sup 201,203,205/Tl, the neutron-deficient isotopes 189-193Tl have been studied using the collinear fast atom beam laser spectroscopy system at UNISOR on-line to the Holifield Heavy Ion Research Facility. A sensitive system for the measurements was developed since the light isotopes were available in mass-separated beams of only 7 x 104 to 4 x 105 atoms per second. By laser excitation of the 535 nm atomic transitions of atoms in the beam, the 6s27s 2S/sub 1/2/ and 6s26s 2P/sub 3/2/ hyperfine structures were measured, as were the isotope shifts of the 535 nm transitions. From these, the magnetic dipole moments, spectroscopic quadrupole moments and isotopic changes in mean-square charge radius were deduced. The magnetic dipole moments are consistent with previous data. The /sup 190,192/Tl isotopes show a considerable difference in quadrupole deformations as well as an anomalous isotope shift with respect to 194Tl. A large isomer shift in 193Tl is observed implying a larger deformation in the 9/2- isomer than in the 1/2+ ground state. The /sup 189,191,193/Tl isomers show increasing deformation away from stability. A deformed shell model calculation indicates that this increase in deformation can account for the dropping of the 9/2- band in these isotopes while an increase in neutron pairing correlations, having opposite and compensating effects on the rotational moment of inertia, maintains the 9/2- strong-coupled band structure. 105 refs., 27 figs

  2. Multimodal Raman-fluorescence spectroscopy of formalin fixed samples is able to discriminate brain tumors from dysplastic tissue

    Science.gov (United States)

    Anand, Suresh; Cicchi, Riccardo; Giordano, Flavio; Buccoliero, Anna Maria; Pavone, Francesco Saverio

    2014-05-01

    In the recent years, there has been a considerable surge in the application of spectroscopy for disease diagnosis. Raman and fluorescence spectra provide characteristic spectral profile related to biochemical and morphological changes when tissues progress from normal state towards malignancy. Spectroscopic techniques offer the advantage of being minimally invasive compared to traditional histopathology, real time and quantitative. In biomedical optical diagnostics, freshly excised specimens are preferred for making ex-vivo spectroscopic measurements. With regard to fresh tissues, if the lab is located far away from the clinic it could pose a problem as spectral measurements have to be performed immediately after dissection. Tissue samples are usually placed in a fixative agent such as 4% formaldehyde to preserve the samples before processing them for routine histopathological studies. Fixation prevents the tissues from decomposition by arresting autolysis. In the present study, we intend to investigate the possibility of using formalin fixed samples for discrimination of brain tumours from dysplastic tissue using Raman and fluorescence spectroscopy. Formalin fixed samples were washed with phosphate buffered saline for about 5 minutes in order to remove the effects of formalin during spectroscopic measurements. In case of fluorescence spectroscopy, changes in spectral profile have been observed in the region between 550-670 nm between dysplastic and tumor samples. For Raman measurements, we found significant differences in the spectral profiles between dysplasia and tumor. In conclusion, formalin fixed samples can be potentially used for the spectroscopic discrimination of tumor against dysplastic tissue in brain samples.

  3. In situ preparation and fluorescence quenching properties of polythiophene/ZnO nanocrystals hybrids through atom-transfer radical polymerization and hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Peng Xiaoming; Zhang Lin [Department of Chemistry, Nanchang University, Xuefu Road 999, Nanchang 330031 (China); Institute of Polymers/Institute for Advanced study, Nanchang University, Xuefu Road 999, Nanchang 330031 (China); Chen Yiwang, E-mail: ywchen@ncu.edu.cn [Department of Chemistry, Nanchang University, Xuefu Road 999, Nanchang 330031 (China); Institute of Polymers/Institute for Advanced study, Nanchang University, Xuefu Road 999, Nanchang 330031 (China); Li Fan, E-mail: lfan@ncu.edu.cn [Institute of Polymers/Institute for Advanced study, Nanchang University, Xuefu Road 999, Nanchang 330031 (China); Zhou Weihua [Institute of Polymers/Institute for Advanced study, Nanchang University, Xuefu Road 999, Nanchang 330031 (China)

    2010-02-15

    In this paper, a new approach for in situ preparing nanocomposites of conjugated polymers (CPs) and semiconductor nanocrystals was developed. Polythiophene grafted poly(zinc methacrylate) (PTh-g-PZMA) copolymer was synthesized by atom-transfer radical polymerization (ATRP) of zinc methacrylate (ZMA) initiated from the macroinitiator poly(2,5-(3-(bromoisopropyl-carbonyl-oxymethylene) thiophene)) (PTh-Br) with pendant initiator groups. Subsequently, the polythiophene grafted poly(methacrylate)/ZnO (PTh-g-PMA/ZnO) hybrid heterojunction nanocomposites were successfully prepared by in situ hydrolysis of PTh-g-PZMA casting films in alkaline aqueous solution. The structures of PTh-Br, PTh-g-PZMA and PTh-g-PMA/ZnO were confirmed by the proton nuclear magnetic resonance ({sup 1}H NMR) spectra, Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS). The morphologies of PTh-g-PMA/ZnO films prepared for different hydrolysis time were observed in the cross-sections by scanning electron microscope (SEM). The SEM images revealed that ZnO nanocrystals were uniformly dispersed in polymers without any aggregation and the appearances of ZnO nanocrystals changed from nanoparticles to nanorods with the hydrolysis treatment time increasing. The optical properties of these nanocomposites were studied by ultraviolet-visible (UV-vis) absorption and fluorescence spectroscopy. UV-vis absorption spectroscopy showed that the adsorption band of PTh-g-PMA/ZnO hybrids was broader than that of PTh-Br, implying that the existence of ZnO nanocrystals increased the optical absorption region of hybrids. The photoluminescence (PL) spectra of the hybrids showed that fluorescence quenching occurred in PTh-g-PMA/ZnO blends and a maximum of 85% of the fluorescence intensity quenched in the PTh-g-PMA/ZnO obtained from treatment in NaOH aqueous solution for 2 h, which revealed the existence of photo-induced charge transfer between the polythiophene chains and ZnO. These results

  4. Detection and characterization of chemical-induced abnormal tissue and rat tumors at different stages using fluorescence spectroscopy

    Science.gov (United States)

    Chen, Wei R.; Jassemnejad, Baha; Crull, Jason; Knobbe, Edward T.; Nordquist, Robert E.

    1996-04-01

    Fluorescence spectroscopy of diseased tissues, including chemical-induced rat liver, kidney and testis lesions, as well as murine mammary tumor, was studied. The rat liver, kidney and testis tissues were excited by radiation of 350 and 366 nm, which appeared to provide the optimal differentiation between normal and lesion tissues; the tumor tissues were excited by both 350 nm and 775 nm wavelengths. In comparison with normal liver tissue, at (lambda) ex equals 366 nm, the fluorescent spectrum of liver lesion showed a clear red shift around the emission peak of 470 nm, the major native fluorescent peak of organized tissue. When excited by 350 nm wavelength, all the chemically induced lesion tissues (liver, kidney and testis) appeared to cause a significant reduction of emission intensity at the 470 nm peak. While the 775 nm excitation did not reveal any significant difference among tumor, muscle and skin tissues, the 350 nm excitation did provide some interesting features among the tumor tissues at different stages. Compared with muscle tissue, the viable tumor showed an overall reduction of emission intensity around 470 nm. In addition, the viable tumor tissue showed a secondary emission peak at 390 nm with necrotic tumor tissue having a reduced intensity. The histology of both viable and necrotic tumor tissue was examined and appeared to correlate with the results of the fluorescent spectroscopy observation.

  5. Study of Organic Matter in Soils of the Amazon Region Employing Laser Induced Fluorescence Spectroscopy

    Science.gov (United States)

    Tadini, Amanda Maria; Nicolodelli, Gustavo; Mounier, Stéphane; Montes, Célia Regina; Marcondes Bastos Pereira Milori, Débora

    2014-05-01

    In the face of climate change and increasing CO2 levels in the atmosphere, the global carbon cycle, soil organic carbon (SOC) sequestration, and the role of different world biomes as potential sources and sinks of carbon are receiving increasing attention. Carbon quantification is an important environmental indicator, but the structure of organic matter is also important because is related to carbon stability. The synthesis of soil organic matter (SOM), as presented in soils of forest vegetation, can be originated from condensation polymeric polyphenols and quinones that are responsible for controlling the main physical-chemical properties of soils. These systems are present in humic substances, representing the major fluorophore of SOM[1-3]. Abiotic factors, such as soil texture, use and occupation of soil, can influence on the process of SOM formation, molecular structure and in its humification index[4]. Laser Induced Fluorescence Spectroscopy (LIFS) have become a promising technique for assessing humification index of SOM (HLIFS). In this context, the aim of this study was to analyze the humification index of the SOM in the region of Barcelos (Amazon) employing LIFS. The study area was the region of Barcelos, close the river Demeni. The whose vegetation distribution in this area, is two biomes the Dense Ombrophylous Forest (DPQD) and Campinarana (DPQT), with areas of edaphic contacts between these two phytophysiognomies, which ranged from Open field (FDE) to closed Depression (DPQ). Preliminary results showed that the area closed Depression (DPQ) there was a continuous gradient of humification with increasing soil depth. A similar behavior was verified for area Forest (DPQD), where the highest values of HLIFS were obtained between the four points analyzed, indicating the magnitude of the molecular recalcitrance this organic matter in this area. The results obtained for area Campinarana (DPQT) and Open field (FDE) showed an opposite behavior. These points there

  6. High-speed low-cost correlator for single molecule fluorescence correlation spectroscopy

    Science.gov (United States)

    Lee, Hsu-Yang; Lin, Hsin-Yu; White, Jonathon D.; Fann, Wunshain

    2009-02-01

    Fluorescence correlation spectroscopy (FCS) has been extensively applied to study the kinetics and photophysics of molecules as well as interactions between molecules by extracting information from the fluctuation of signals. In particular, single molecule applications of FCS promise the greatest amounts of information. Ideally, one would like to carry out FCS in real-time; however, due to the time-consuming nature of the correlation process, performing the correlation in real-time is totally nontrivial. Generally an expensive hardware correlator or a TCSPC board is required for this purpose. Recently highly-efficient algorithms based on multi-tau method have been proposed to build up a software correlator. In this work, we set forth an innovative algorithm capable of realizing the real-time correlation, without turning to the multi-tau method. This algorithm takes advantage of the low count rate generally existing in the FCS experiments, directly using the time interval between each photon its adjacent photon to efficiently update the correlation function. Based on this efficiency, it is possible to build a low-cost software correlator with just an ordinary counter board. We practically demonstrate the feasibility by setting up this correlator to measure the diffusion motion of rhodamine 6G in water using FCS. The algorithm was validated by duplicating the signal from the photon detector and sending it to both the ordinary counter board with our software correlator and a commercial correlator simultaneously. The perfect coincidence of the correlation curves from these two correlators and the real-time display of the correlation function indicate the validity and practicability of our approach.

  7. Fluorescence correlation spectroscopy diffusion laws in the presence of moving nanodomains

    Science.gov (United States)

    Šachl, Radek; Bergstrand, Jan; Widengren, Jerker; Hof, Martin

    2016-03-01

    It has been shown by means of simulations that spot variation fluorescence correlation spectroscopy (sv-FCS) can be used for the identification and, to some extent, also characterization of immobile lipid nanodomains in model as well as cellular plasma membranes. However, in these simulations, the nanodomains were assumed to be stationary, whereas they actually tend to move like the surrounding lipids. In the present study, we investigated how such domain movement influences the diffusion time/spot-size dependence observed in FCS experiments, usually referred to as ‘diffusion law’ analysis. We show that domain movement might mask the effects of the ‘anomalous’ diffusion characteristics of membrane lipids or proteins predicted for stationary domains, making it difficult to identify such moving nanodomains by sv-FCS. More specifically, our simulations indicate that (i) for domains moving up to a factor of 2.25 slower than the surrounding lipids, such impeded diffusion cannot be observed and the diffusion behaviour of the proteins or lipids is indistinguishable from that of freely diffusing molecules, i.e. nanodomains are not detected; (ii) impeded protein/lipid diffusion behaviour can be observed in experiments where the radii of the detection volume are similar in size to the domain radii, the domain diffusion is about 10 times slower than that of the lipids, and the probes show a high affinity to the domains; and (iii) presence of nanodomains can only be reliably detected by diffraction limited sv-FCS when the domains move very slowly (about 200 times slower than the lipid diffusion). As nanodomains are expected to be in the range of tens of nanometres and most probes show low affinities to such domains, sv-FCS is limited to stationary domains and/or STED-FCS. However, even for that latter technique, diffusing domains smaller than 50 nm in radius are hardly detectable by FCS diffusion time/spot-size dependencies.

  8. Measurement of OH reactivity by laser flash photolysis coupled with laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Stone, Daniel; Whalley, Lisa K.; Ingham, Trevor; Edwards, Peter M.; Cryer, Danny R.; Brumby, Charlotte A.; Seakins, Paul W.; Heard, Dwayne E.

    2016-07-01

    OH reactivity (k'OH) is the total pseudo-first-order loss rate coefficient describing the removal of OH radicals to all sinks in the atmosphere, and is the inverse of the chemical lifetime of OH. Measurements of ambient OH reactivity can be used to discover the extent to which measured OH sinks contribute to the total OH loss rate. Thus, OH reactivity measurements enable determination of the comprehensiveness of measurements used in models to predict air quality and ozone production, and, in conjunction with measurements of OH radical concentrations, to assess our understanding of OH production rates. In this work, we describe the design and characterisation of an instrument to measure OH reactivity using laser flash photolysis coupled to laser-induced fluorescence (LFP-LIF) spectroscopy. The LFP-LIF technique produces OH radicals in isolation, and thus minimises potential interferences in OH reactivity measurements owing to the reaction of HO2 with NO which can occur if HO2 is co-produced with OH in the instrument. Capabilities of the instrument for ambient OH reactivity measurements are illustrated by data collected during field campaigns in London, UK, and York, UK. The instrumental limit of detection for k'OH was determined to be 1.0 s-1 for the campaign in London and 0.4 s-1 for the campaign in York. The precision, determined by laboratory experiment, is typically atmospheric chamber for measurements of OH reactivity during simulated experiments, and provide suggestions for future improvements to OH reactivity LFP-LIF instruments.

  9. Direct observation of T4 lysozyme hinge-bending motion by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Yirdaw, Robel B; McHaourab, Hassane S

    2012-10-01

    Bacteriophage T4 Lysozyme (T4L) catalyzes the hydrolysis of the peptidoglycan layer of the bacterial cell wall late in the infection cycle. It has long been postulated that equilibrium dynamics enable substrate access to the active site located at the interface between the N- and C-terminal domains. Crystal structures of WT-T4L and point mutants captured a range of conformations that differ by the hinge-bending angle between the two domains. Evidence of equilibrium between open and closed conformations in solution was gleaned from distance measurements between the two domains but the nature of the equilibrium and the timescale of the underlying motion have not been investigated. Here, we used fluorescence fluctuation spectroscopy to directly detect T4L equilibrium conformational fluctuations in solution. For this purpose, Tetramethylrhodamine probes were introduced at pairs of cysteines in regions of the molecule that undergo relative displacement upon transition from open to closed conformations. Correlation analysis of Tetramethylrhodamine intensity fluctuations reveals hinge-bending motion that changes the relative distance and orientation of the N- and C-terminal domains with ≅ 15 μs relaxation time. That this motion involves interconversion between open and closed conformations was further confirmed by the dampening of its amplitude upon covalent substrate trapping. In contrast to the prevalent two-state model of T4L equilibrium, molecular brightness and number of particles obtained from cumulant analysis suggest that T4L populates multiple intermediate states, consistent with the wide range of hinge-bending angles trapped in the crystal structure of T4L mutants.

  10. Resonant inelastic scattering in dilute magnetic semiconductors by x-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lawniczak-Jablonska, K. [Lawrence Berkeley National Lab., CA (United States)]|[Institute of Physics, Warsaw (Poland); Jia, J.J.; Underwood, J.H. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    As modern, technologically important materials have become more complex, element specific techniques have become invaluable in studying the electronic structure of individual components from the system. Soft x-ray fluorescence (SXF) and absorption (SXA) spectroscopies provide a unique means of measuring element and angular momentum density of electron states, respectively, for the valence and conducting bands in complex materials. X-ray absorption and the decay through x-ray emission are generally assumed to be two independent one-photon processes. Recent studies, however have demonstrated that SXF excited near the absorption threshold generate an array of spectral features that depend on nature of materials, particularly on the localization of excited states in s and d-band solids and that these two processes can no be longer treated as independent. Resonant SXF offers thus the new way to study the dynamics of the distribution of electronic valence states in the presence of a hole which is bound to the electron low lying in the conduction band. This process can simulate the interaction between hole-electron pair in wide gap semiconductors. Therefore such studies can help in understanding of transport and optics phenomena in the wide gap semiconductors. The authors report the result of Mn and S L-resonant emission in Zn{sub 1{minus}x}Mn{sub x}S (with x=0.2 and 0.3) and MnS as the energy of exciting radiation is tuned across the Mn and S L{sub 3,2} absorption edge, along with the resonant excited spectra from elemental Mn as a reference.

  11. Ex vivo optical coherence tomography and laser induced fluorescence spectroscopy imaging of murine gastrointestinal tract

    Science.gov (United States)

    Hariri, Lida; Tumlinson, Alexandre R.; Wade, Norman; Besselsen, David; Utzinger, Urs; Gerner, Eugene; Barton, Jennifer

    2005-04-01

    Optical Coherence Tomography (OCT) and Laser Induced Fluorescence Spectroscopy (LIF) have separately been found to have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models of human disease is unknown. We combine the two modalities to survey the GI tract of a variety of mouse strains and sample dysplasias and inflammatory bowel disease (IBD) of the small and large intestine. Segments of duodenum and lower colon 2.5 cm in length and the entire esophagus from 10 mice each of two colon cancer models (ApcMin and AOM treated A/J) and two IBD models (Il-2 and Il-10) and 5 mice each of their respective controls were excised. OCT images and LIF spectra were obtained simultaneously from each tissue sample within 1 hour of extraction. Histology was used to classify tissue regions as normal, Peyer"s patch, dysplasia, adenoma, or IBD. Features in corresponding regions of OCT images were analyzed. Spectra from each of these categories were averaged and compared via the student's t-test. Features in OCT images correlated to histology in both normal and diseased tissue samples. In the diseased samples, OCT was able to identify early stages of mild colitis and dysplasia. In the sample of IBD, the LIF spectra displayed unique peaks at 635nm and 670nm, which were attributed to increased porphyrin production in the proliferating bacteria of the disease. These peaks have the potential to act as a diagnostic for IBD. OCT and LIF appear to be useful and complementary modalities for imaging mouse models.

  12. Laser absorption spectroscopy diagnostics of helium metastable atoms generated in dielectric barrier discharge cryoplasmas

    Science.gov (United States)

    Urabe, Keiichiro; Muneoka, Hitoshi; Stauss, Sven; Sakai, Osamu; Terashima, Kazuo

    2015-10-01

    Cryoplasmas, which are plasmas whose gas temperatures are below room temperature (RT), have shown dynamic changes in their physical and chemical characteristics when the gas temperature in the plasmas (Tgp) was decreased from RT. In this study, we measured the temporal behavior of helium metastable (Hem) atoms generated in a parallel-plate dielectric barrier discharge at ambient gas temperatures (Tga) of 300, 100, and 14 K and with a gas density similar to atmospheric conditions by laser absorption spectroscopy. The increments of Tgp to Tga were less than 20 K. We found from the results that the Hem lifetime and maximum density become longer and larger over one order of magnitude for lower Tga. The reasons for the long Hem lifetime at low Tga are decreases in the rate coefficients of three-body Hem quenching reactions and in the amounts of molecular impurities with boiling points higher than that of He.

  13. Atoms, molecules and optical physics 2. Molecules and photons - Spectroscopy and collisions

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, Ingolf V.; Schulz, Claus-Peter [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie im Forschungsverbund Berlin e.V. (Germany)

    2015-09-01

    This is the second volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 2 introduces lasers and quantum optics, while the main focus is on the structure of molecules and their spectroscopy, as well as on collision physics as the continuum counterpart to bound molecular states. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

  14. The in-gas-jet laser ion source: resonance ionization spectroscopy of radioactive atoms in supersonic gas jets

    OpenAIRE

    Kudryavtsev, Yu; Ferrer, R; Huyse, M.; Van den Bergh, P.; Van Duppen, P.(KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, Leuven, 3001, Belgium)

    2012-01-01

    New approaches to perform efficient and selective step-wise Resonance Ionization Spectroscopy (RIS) of radioactive atoms in different types of supersonic gas jets are proposed. This novel application results in a major expansion of the In-Gas Laser Ionization and Spectroscopy (IGLIS) method developed at KU Leuven. Implementation of resonance ionization in the supersonic gas jet allows to increase the spectral resolution by one order of magnitude in comparison with the currently performed in-g...

  15. Atom-specific look at the surface chemical bond using x-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, A.; Wassdahl, N.; Weinelt, M. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    CO and N{sub 2} adsorbed on the late transition metals have become prototype systems regarding the general understanding of molecular adsorption. It is in general assumed that the bonding of molecules to transition metals can be explained in terms of the interaction of the frontier HOMO and LUMO molecular orbitals with the d-orbitals. In such a picture the other molecular orbitals should remain essentially the same as in the free molecule. For the adsorption of the isoelectronic molecules CO and N{sub 2} this has led to the so called Blyholder model i.e., a synergetic {sigma} (HOMO) donor and {pi} (LUMO) backdonation bond. The authors results at the ALS show that such a picture is oversimplified. The direct observation and identification of the states related to the surface chemical bond is an experimental challenge. For noble and transition metal surfaces, the adsorption induced states overlap with the metal d valence band. Their signature is therefore often obscured by bulk substrate states. This complication has made it difficult for techniques such as photoemission and inverse photoemission to provide reliable information on the energy of chemisorption induced states and has left questions unanswered regarding the validity of the frontier orbitals concept. Here the authors show how x-ray emission spectroscopy (XES), in spite of its inherent bulk sensitivity, can be used to investigate adsorbed molecules. Due to the localization of the core-excited intermediate state, XE spectroscopy allows an atomic specific separation of the valence electronic states. Thus the molecular contributions to the surface measurements make it possible to determine the symmetry of the molecular states, i.e., the separation of {pi} and {sigma} type states. In all the authors can obtain an atomic view of the electronic states involved in the formation of the chemical bond to the surface.

  16. Fluorescence spectroscopy as a means of distinguishing fulvic and humic acids from dissolved and sedimentary aquatic sources and terrestrial sources

    Science.gov (United States)

    Senesi, Nicola; Miano, Teodoro M.; Provenzano, Maria Rosaria

    Thirteen fulvic acids (FA) and humic acids (HA) isolated from river waters and sediment, marine sediments, leonardite, soils, and paleosol, have been investigated by fluorescence spectroscopy in the emission, excitation and, partly, synchronous scan excitation modes. Emission spectra are generally characterized by a unique broad band, whereas excitation spectra exhibit a variable number of peaks or shoulders of various intensity; these peaks are particularly well-resolved for sedimentary HA samples. A decrease in the relative intensity of fluorescence, which is associated with a red-shift (longer wavelengths) of both the emission maximum and the main excitation peaks, is observed when passing from dissolved aquatic and soil FA to river and marine sedimentary HA, to leonardite and soil HA, and, finally, to paleosol HA. Evident differences are shown in the relative intensity and wavelength maxima, measured in any mode, between soil FA and HA from the same source. For FA and HA of various nature and origin, the fluorescence is suggested to be caused by chemically different structural units. These units fluoresce from the blue-violet to the green and consist of variously extended, condensed, aromatic and/or heterocyclic ring systems, with a high degree of electronic conjugation and bearing suitable hydroxyl, alkoxyl and carbonyl groups (e.g. salicyl, cinnamic and hydroxybenzoic derivatives, naphtols, naphtoquinones, coumarin), and quinoline-derivatives, flavonoids and Schiffbase derivatives. Fluorescence properties of humic substances may represent an additional diagnostic criterium useful in distinguishing between FA and HA from the same or various natural sources.

  17. Spectroscopy of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) attached to rare gas samples: Clusters vs. bulk matrices. II. Fluorescence emission spectroscopy

    Science.gov (United States)

    Dvorak, Matthieu; Müller, Markus; Knoblauch, Tobias; Bünermann, Oliver; Rydlo, Alexandre; Minniberger, Stefan; Harbich, Wolfgang; Stienkemeier, Frank

    2012-10-01

    The interaction between 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. Laser-excited PTCDA-doped large argon, neon, and para-hydrogen clusters along with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground state takes place. In comparison, fluorescence emission studies of PTCDA embedded in bulk neon and argon matrices result in much more complex spectral signatures characterized by a splitting of the different emission lines. These can be assigned to the appearance of site isomers of the surrounding matrix lattice structure.

  18. Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

    Science.gov (United States)

    Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

    2006-08-01

    A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light. PMID:16925920

  19. Photolytic-interference-free, femtosecond, two-photon laser-induced fluorescence imaging of atomic oxygen in flames

    Science.gov (United States)

    Kulatilaka, Waruna D.; Roy, Sukesh; Jiang, Naibo; Gord, James R.

    2016-02-01

    Ultrashort-pulse lasers are well suited for nonlinear diagnostic techniques such as two-photon laser-induced fluorescence (TPLIF) because the signals generated scale as the laser intensity squared. Furthermore, the broad spectral bandwidths associated with nearly Fourier-transform-limited ultrashort pulses effectively contribute to efficient nonlinear excitation by coupling through a large number of in-phase photon pairs, thereby producing strong fluorescence signals. Additionally, femtosecond (fs)-duration amplified laser systems typically operate at 1-10 kHz repetition rates, enabling high-repetition-rate imaging in dynamic environments. In previous experiments, we have demonstrated utilization of fs pulses for kilohertz (kHz)-rate, interference-free imaging of atomic hydrogen (H) in flames. In the present study, we investigate the utilization of fs-duration pulses to photolytic-interference-free TPLIF imaging of atomic oxygen (O). In TPLIF of O, photodissociation of vibrationally excited carbon dioxide (CO2) is known to be the prominent interference that produces additional O atoms in the medium. We have found that through the use of fs excitation, such interferences can be virtually eliminated in premixed laminar methane flames, which paves the way for two-dimensional imaging of O at kHz data rates. Such measurements can provide critical data for validating complex, multidimensional turbulent-combustion models as well as for investigating flame dynamics in practical combustion devices.

  20. Direct determination of mercury in white vinegar by matrix assisted photochemical vapor generation atomic fluorescence spectrometry detection

    Energy Technology Data Exchange (ETDEWEB)

    Liu Qingyang, E-mail: liuqingyang0807@yahoo.com.c [Beijing Center for Physical and Chemical Analysis, Beijing 100089 (China)

    2010-07-15

    This paper proposes the use of photochemical vapor generation with acetic acid as sample introduction for the direct determination of ultra-trace mercury in white vinegars by atomic fluorescence spectrometry. Under ultraviolet irradiation, the sample matrix (acetic acid) can reduce mercury ion to atomic mercury Hg{sup 0}, which is swept by argon gas into an atomic fluorescence spectrometer for subsequent analytical measurements. The effects of several factors such as the concentration of acetic acid, irradiation time, the flow rate of the carrier gas and matrix effects were discussed and optimized to give detection limits of 0.08 ng mL{sup -1} for mercury. Using the experimental conditions established during the optimization (3% v/v acetic acid, 30 s irradiation time and 20 W mercury lamp), the precision levels, expressed as relative standard deviation, were 4.6% (one day) and 7.8% (inter-day) for mercury (n = 9). Addition/recovery tests for evaluation of the accuracy were in the range of 92-98% for mercury. The method was also validated by analysis of vinegar samples without detectable amount of Hg spiked with aqueous standard reference materials (GBW(E) 080392 and GBW(E) 080393). The results were also compared with those obtained by acid digestion procedure and determination of mercury by ICP-MS. There was no significant difference between the results obtained by the two methods based on a t-test (at 95% confidence level).