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Sample records for infrared multiphoton excitation

  1. Multiphoton microscopy with near infrared contrast agents

    PubMed Central

    Yazdanfar, Siavash; Joo, Chulmin; Zhan, Chun; Berezin, Mikhail Y.; Akers, Walter J.; Achilefu, Samuel

    2010-01-01

    While multiphoton microscopy (MPM) has been performed with a wide range of excitation wavelengths, fluorescence emission has been limited to the visible spectrum. We introduce a paradigm for MPM of near-infrared (NIR) fluorescent molecular probes via nonlinear excitation at 1550 nm. This all-NIR system expands the range of available MPM fluorophores, virtually eliminates background autofluorescence, and allows for use of fiber-based, turnkey ultrafast lasers developed for telecommunications. PMID:20614991

  2. Relaxation channels of multi-photon excited xenon clusters.

    PubMed

    Serdobintsev, P Yu; Rakcheeva, L P; Murashov, S V; Melnikov, A S; Lyubchik, S; Timofeev, N A; Pastor, A A; Khodorkovskii, M A

    2015-09-21

    The relaxation processes of the xenon clusters subjected to multi-photon excitation by laser radiation with quantum energies significantly lower than the thresholds of excitation of atoms and ionization of clusters were studied. Results obtained by means of the photoelectron spectroscopy method showed that desorption processes of excited atoms play a significant role in the decay of two-photon excited xenon clusters. A number of excited states of xenon atoms formed during this process were discovered and identified. PMID:26395700

  3. Multiphoton interband excitations of quantum gases in driven optical lattices

    NASA Astrophysics Data System (ADS)

    Weinberg, M.; Ölschläger, C.; Sträter, C.; Prelle, S.; Eckardt, A.; Sengstock, K.; Simonet, J.

    2015-10-01

    We report on the observation of multiphoton interband absorption processes for quantum gases in shaken light crystals. Periodic inertial forcing, induced by a spatial motion of the lattice potential, drives multiphoton interband excitations of up to the ninth order. The occurrence of such excitation features is systematically investigated with respect to the potential depth and the driving amplitude. Ab initio calculations of resonance positions as well as numerical evaluation of their strengths exhibit good agreement with experimental data. In addition our findings could make it possible to reach novel phases of quantum matter by tailoring appropriate driving schemes.

  4. Multiphoton electron detachment studies of C 7H 7- using a low-power infrared laser. Competition of radiative and collisional relaxation with vibrational excitation

    NASA Astrophysics Data System (ADS)

    Wight, Charles A.; Beauchamp, J. L.

    1989-07-01

    Infrared laser-induced electron detachment from C 6H 5CH 2-, C 6D 5CH 2- and cyclo-C 7H 7- has been investigated by ion cyclotron resonance spectroscopy. Anions are trapped at low pressure for up to several seconds and are uniformly irradiated with the unfocused output of a cw CO 2 laser. Electron detachment is monitored as a function of irradiation period, laser intensity, wave-length and neutral gas pressure. Infrared photodetachment spectra of C 6H 5CH 2- and C 6D 5CH 2- exhibit bands at 945 and 932 cm -1, respectively, while the spectrum of cyclo-C 7H 7- shows only slight dependence on laser frequency between 920 and 1080 cm -1. Modeling of the C 6H 5CH 2- photodetachment kinetics suggests that one step in the laser excitation process is rate limiting. Radiative relaxation does not appear to be significant at laser intensities greater than 10 W cm -2 and collisions with neutral molecules are only moderately effective in deactivating vibrationally excited anions.

  5. Multiphoton ionization and excitation spectroscopy of molecules in liquids. [Fluoranthene

    SciTech Connect

    Siomos, K.; Faidas, H.; Christophorou, L.G.

    1984-01-01

    The two-photon ionization and excitation spectra of fluoranthene in liquid n-pentane have been measured and together with laser power versus signal intensity measurements have been utilized to elucidate the multiphoton ionization mechanism for this and other molecules in liquids.

  6. Multiphoton excitation in spin split two-dimensional electron gas

    NASA Astrophysics Data System (ADS)

    Gumber, Sukirti; Kumar, Manoj; Jha, Pradip Kumar; Mohan, Man

    2015-12-01

    The terahertz radiation induced multiphoton excitation processes have been studied in a two dimensional electron gas where the mixing of spin-up and spin-down states of neighbouring Landau levels by Rashba spin orbit interaction results in two new, unequally spaced energy branches. The multiphoton transitions between different quasi-spin branches of electron gas are found to be dominant over transitions involving the states from the same branch. It has been observed that enhancement and power-broadening of absorption spectrum can be effectively tuned by strength and frequency of the laser field as well as the spin-orbit coupling.

  7. Individual bioaerosol particle discrimination by multi-photon excited fluorescence.

    PubMed

    Kiselev, Denis; Bonacina, Luigi; Wolf, Jean-Pierre

    2011-11-21

    Femtosecond laser induced multi-photon excited fluorescence (MPEF) from individual airborne particles is tested for the first time for discriminating bioaerosols. The fluorescence spectra, analysed in 32 channels, exhibit a composite character originating from simultaneous two-photon and three-photon excitation at 790 nm. Simulants of bacteria aggregates (clusters of dyed polystyrene microspheres) and different pollen particles (Ragweed, Pecan, Mulberry) are clearly discriminated by their MPEF spectra. This demonstration experiment opens the way to more sophisticated spectroscopic schemes like pump-probe and coherent control. PMID:22109478

  8. vuv fluorescence from selective high-order multiphoton excitation of N{sub 2}

    SciTech Connect

    Coffee, Ryan N.; Gibson, George N.

    2004-05-01

    Recent fluorescence studies suggest that ultrashort pulse laser excitation may be highly selective. Selective high-intensity laser excitation holds important consequences for the physics of multiphoton processes. To establish the extent of this selectivity, we performed a detailed comparative study of the vacuum ultraviolet fluorescence resulting from the interaction of N{sub 2} and Ar with high-intensity infrared ultrashort laser pulses. Both N{sub 2} and Ar reveal two classes of transitions, inner-valence ns <- np and Rydberg np <- n{sup '}l{sup '}. From their pressure dependence, we associate each transition with either plasma or direct laser excitation. Furthermore, we qualitatively confirm such associations with the time dependence of the fluorescence signal. Remarkably, only N{sub 2} presents evidence of direct laser excitation. This direct excitation produces ionic nitrogen fragments with inner-valence (2s) holes, two unidentified transitions, and one molecular transition, the N{sub 2}{sup +}:X {sup 2}{sigma}{sub g}{sup +} <- C {sup 2}{sigma}{sub u}{sup +}. We discuss these results in the light of a recently proposed model for multiphoton excitation.

  9. Infrared multiphoton resummation in quantum electrodynamics

    E-print Network

    Mati, P

    2015-01-01

    Infrared singularities in massless gauge theories are known since the foundation of quantum field theories. The root of this problem can be tracked back to the very definition of these long-range interacting theories such as QED. It can be shown that singularities are caused by the massless degrees of freedom (i.e. the photons in the case of QED). In the Bloch-Nordsieck model the absence of the infrared catastrophe can be shown exactly by the complete summation of the radiative corrections. In this paper we will give the idea of the derivation of the Bloch-Nordsieck propagator, that describes the infrared structure of the electron propagation, at zero and finite temperatures. Some ideas of the possible applications are also mentioned.

  10. Multiphoton dissociation and thermal unimolecular reactions induced by infrared lasers. [REAMPA code

    SciTech Connect

    Dai, H.L.

    1981-04-01

    Multiphoton dissociation (MPD) of ethyl chloride was studied using a tunable 3.3 ..mu..m laser to excite CH stretches. The absorbed energy increases almost linearly with fluence, while for 10 ..mu..m excitation there is substantial saturation. Much higher dissociation yields were observed for 3.3 ..mu..m excitation than for 10 ..mu..m excitation, reflecting bottlenecking in the discrete region of 10 ..mu..m excitation. The resonant nature of the excitation allows the rate equations description for transitions in the quasicontinuum and continuum to be extended to the discrete levels. Absorption cross sections are estimated from ordinary ir spectra. A set of cross sections which is constant or slowly decreasing with increasing vibrational excitation gives good fits to both absorption and dissociation yield data. The rate equations model was also used to quantitatively calculate the pressure dependence of the MPD yield of SF/sub 6/ caused by vibrational self-quenching. Between 1000-3000 cm/sup -1/ of energy is removed from SF/sub 6/ excited to approx. > 60 kcal/mole by collision with a cold SF/sub 6/ molecule at gas kinetic rate. Calculation showed the fluence dependence of dissociation varies strongly with the gas pressure. Infrared multiphoton excitation was applied to study thermal unimolecular reactions. With SiF/sub 4/ as absorbing gas for the CO/sub 2/ laser pulse, transient high temperature pulses were generated in a gas mixture. IR fluorescence from the medium reflected the decay of the temperature. The activation energy and the preexponential factor of the reactant dissociation were obtained from a phenomenological model calculation. Results are presented in detail. (WHK)

  11. Nonadiabatic approach for resonant molecular multiphoton absorption processes in intense infrared laser fields

    E-print Network

    Ho, Tak-San; Chu, Shih-I

    1983-07-14

    A nonperturbative approach for efficient and accurate treatment of the molecular multiphoton absorption (MPA) quantum dynamics in intense infrared (IR) laser fields is presented. The approach is based on the adiabatic separation of the fast...

  12. Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy.

    PubMed Central

    Xu, C; Zipfel, W; Shear, J B; Williams, R M; Webb, W W

    1996-01-01

    Intrinsic, three-dimensionally resolved, microscopic imaging of dynamical structures and biochemical processes in living preparations has been realized by nonlinear laser scanning fluorescence microscopy. The search for useful two-photon and three-photon excitation spectra, motivated by the emergence of nonlinear microscopy as a powerful biophysical instrument, has now discovered a virtual artist's palette of chemical indicators, fluorescent markers, and native biological fluorophores, including NADH, flavins, and green fluorescent proteins, that are applicable to living biological preparations. More than 25 two-photon excitation spectra of ultraviolet and visible absorbing molecules reveal useful cross sections, some conveniently blue-shifted, for near-infrared absorption. Measurements of three-photon fluorophore excitation spectra now define alternative windows at relatively benign wavelengths to excite deeper ultraviolet fluorophores. The inherent optical sectioning capability of nonlinear excitation provides three-dimensional resolution for imaging and avoids out-of-focus background and photodamage. Here, the measured nonlinear excitation spectra and their photophysical characteristics that empower nonlinear laser microscopy for biological imaging are described. Images Fig. 1 Fig. 5 Fig. 7 PMID:8855254

  13. ELECTRON DETACHMENT DISSOCIATION AND INFRARED MULTIPHOTON DISSOCIATION OF HEPARIN TETRASACCHARIDES

    PubMed Central

    Leach, Franklin E.; Xiao, Zhongping; Laremore, Tatiana N.; Linhardt, Robert J.; Amster, I. Jonathan

    2011-01-01

    Heparin glycosaminoglycans (GAGs) present the most difficult glycoform for analytical characterization due to high levels of sulfation and structural heterogeneity. Recent contamination of the clinical heparin supply and subsequent fatalities has highlighted the need for sensitive methodologies of analysis. In the last decade, tandem mass spectrometry has been increasingly applied for the analysis of GAGs, but developments in the characterization of highly sulfated compounds have been minimal due to the low number of cross-ring cleavages generated by threshold ion activation by collisional induced dissociation (CID). In the current work, electron detachment dissociation (EDD) and infrared multiphoton dissociation (IRMPD) are applied to a series of heparin tetrasaccharides. With both activation methods, abundant glycosidic and cross-ring cleavages are observed. The concept of Ionized Sulfate Criteria (ISC) is presented as a succinct method for describing the charge state, degree of ionization and sodium/proton exchange in the precursor ion. These factors contribute to the propensity for useful fragmentation during MS/MS measurements. Precursors with ISC values of 0 are studied here, and shown to yield adequate structural information from ion activation by EDD or IRMPD. PMID:22247649

  14. The effects of refractive index heterogeneity within kidney tissue on multiphoton fluorescence excitation microscopy.

    PubMed

    Young, P A; Clendenon, S G; Byars, J M; Dunn, K W

    2011-05-01

    Although multiphoton fluorescence excitation microscopy has improved the depth at which useful fluorescence images can be collected in biological tissues, the reach of multiphoton fluorescence excitation microscopy is nonetheless limited by tissue scattering and spherical aberration. Scattering can be reduced in fixed samples by mounting in a medium whose refractive index closely matches that of the fixed material. Using optical 'clearing', the effects of refractive index heterogeneity on signal attenuation with depth are investigated. Quantitative measurements show that by mounting kidney tissue in a high refractive index medium, less than 50% of signal attenuates in 100 ?m of depth. PMID:21118239

  15. Energetics from Slow Infrared Multiphoton Dissociation of Biomolecules

    PubMed Central

    Jockusch, Rebecca A.; Paech, Kolja

    2005-01-01

    Photodissociation kinetics of the protonated pentapeptide leucine enkephalin measured using a cw CO2 laser and a Fourier-transform mass spectrometer are reported. A short induction period, corresponding to the time required to raise the internal energy of the ion population to a (dissociating) steady state, is observed. After this induction period, the dissociation data are accurately fit by first-order kinetics. A plot of the log of the unimolecular dissociation rate constant, kuni, as a function of the log of laser power is linear at low laser powers (<9 W, kuni <0.05 s?1), but tapers off at high laser power (9–33 W, kuni = 0.05–7 s?1). The entire measured dissociation curve can be accurately fit by an exponential function plus a constant. The experiment is simulated using a master equation formalism. In the model, the laser radiation is described as an energetically flat-topped distribution which is spatially uniform. This description is consistent with experimental results which indicate that ion motion within the cell averages out spatial inhomogeneities in the laser light. The model has several adjustable parameters. The effect of varying these parameters on the calculated kinetics and power dependence curves is discussed. A procedure for determining a limited range of threshold dissociation energy, Eo, which fits both the measured induction period and power dependence curves, is presented. Using this procedure, Eo of leucine enkephalin is determined to be 1.12–1.46 eV. This result is consistent with, although less precise than, values measured previously using blackbody infrared radiative dissociation. Although the blackbody dissociation results were used as a starting point to search for fits of the master equation model to experiment, these results demonstrate that it is, in principle, possible to determine a limited range of Eo from slow infrared multiphoton dissociation data alone. PMID:16467893

  16. Photodynamic therapy and knocking out of single tumor cells by multiphoton excitation processes

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Fischer, Peter; Koenig, Karsten

    2004-09-01

    Near infrared (NIR) ultrashort laser pulses of 780 nm have been used to induce intracellular photodynamic reactions by nonlinear excitation of porphyrin photosensitizers. Intracellular accumulation and photobleaching of the fluorescent photosensitizers protoporphyrin IX and Photofrin (PF) have been studied by non-resonant two-photon fluorescence excitation of PF and aminolevulinic acid (ALA)-labeled Chinese hamster ovary (CHO) cells. To testify the efficacy of both substrates to induce irreversible destructive effects, the cloning efficiency (CE) of cells exposed to femtosecond pulses of a multiphoton laser scanning microscope (40x/1.3) was determined. In the case of Photofrin accumulation, CEs of 50% and 0% were obtained after 17 laserscans (2 mW?, 16 s/ frame) and 50 scans, respectively. All cells exposed to 50 scans died within 48h after laser exposure. 100 scans were required to induce lethal effects in ALA labeled cells. Sensitizer-free control cells could be scanned 250 times (1.1 h) and more without impact on the reproduction behavior, morphology, and vitality. In addition to the slow phototoxic effect by photooxidation processes, another destructive but immediate effect based on optical breakdown was induced when employing high intense NIR femtosecond laser beams. This was used to optically knock out single tumor cells in living mice (solid Ehrlich-Carcinoma) in a depth of 10 to 100 ?m.

  17. Investigations of multiphoton excitation and ionization in a short range potential

    SciTech Connect

    Susskind, S.M.; Cowley, S.C.; Valeo, E.J.

    1989-02-01

    We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a delta-function potential. 9 refs., 3 figs.

  18. Confocal microscopy and multi-photon excitation microscopy of human skin in vivo

    E-print Network

    So, Peter

    , MA 02139 USA ptso@mit.edu Abstract: This paper compares tandem scanning reflected light confocal-dimensional microscopic biopsy of in vivo human skin: a new technique based on a flexible confocal microscope." J. MicrosConfocal microscopy and multi-photon excitation microscopy of human skin in vivo Barry R. Masters

  19. Dissociation of benzylamine ions following infrared multiple photon absorption, electron impact ionization, and UV multiphoton ionization

    SciTech Connect

    Catanzarite, J.H.; Haas, Y.; Reisler, H.; Wittig, C.

    1983-05-01

    The dissociation of benzylamine ions following (i) electron impact (EI) ionization, (ii) multiphoton ionization (MPI) at 266 nm, and (iii) infrared multiple photon absorption (IRMPA) at 9.26 ..mu..m is reported. In the EI and MPI experiments, three competitive dissociation pathways are observed. In the IRMPA experiments, benzylamine ions prepared by MPI at low fluences are fragmented very efficiently following irradiation with the focused output from a pulsed CO/sub 2/ laser. However, in contrast to the EI and MPI results, the IRMPD experiments reveal only a single, lowest energy, dissociation pathway and the fragmentation pattern is consistent with a sequential mechanism in which daughter ions continue to absorb the IR radiation and dissociate. The differences are explained by the different natures of the excitation processes: in IRMPA, the relatively slow up-pumping rate and the long rise time of the CO/sub 2/ laser pulse restrict the levels of excitation in the dissociating parent ions and favor sequential processes along the lowest energy decomposition pathways.

  20. Dissociation of benzylamine ions following infrared multiple photon absorption, electron impact ionization, and UV multiphoton ionizationa)

    NASA Astrophysics Data System (ADS)

    Catanzarite, J. H.; Haas, Y.; Reisler, H.; Wittig, C.

    1983-05-01

    The dissociation of benzylamine ions following (i) electron impact (EI) ionization, (ii) multiphoton ionization (MPI) at 266 nm, and (iii) infrared multiple photon absorption (IRMPA) at 9.26 ?m is reported. In the EI and MPI experiments, three competitive dissociation pathways are observed. In the IRMPA experiments, benzylamine ions prepared by MPI at low fluences are fragmented very efficiently following irradiation with the focused output from a pulsed CO2 laser. However, in contrast to the EI and MPI results, the IRMPD experiments reveal only a single, lowest energy, dissociation pathway and the fragmentation pattern is consistent with a sequential mechanism in which daughter ions continue to absorb the IR radiation and dissociate. The differences are explained by the different natures of the excitation processes: in IRMPA, the relatively slow up-pumping rate and the long rise time of the CO2 laser pulse restrict the levels of excitation in the dissociating parent ions and favor sequential processes along the lowest energy decomposition pathways.

  1. Multiphoton excitation fluorescence microscopy and spectroscopy of in vivo human skin.

    PubMed Central

    Masters, B R; So, P T; Gratton, E

    1997-01-01

    Multiphoton excitation microscopy at 730 nm and 960 nm was used to image in vivo human skin autofluorescence from the surface to a depth of approximately 200 microm. The emission spectra and fluorescence lifetime images were obtained at selected locations near the surface (0-50 microm) and at deeper depths (100-150 microm) for both excitation wavelengths. Cell borders and cell nuclei were the prominent structures observed. The spectroscopic data suggest that reduced pyridine nucleotides, NAD(P)H, are the primary source of the skin autofluorescence at 730 nm excitation. With 960 nm excitation, a two-photon fluorescence emission at 520 nm indicates the presence of a variable, position-dependent intensity component of flavoprotein. A second fluorescence emission component, which starts at 425 nm, is observed with 960-nm excitation. Such fluorescence emission at wavelengths less than half the excitation wavelength suggests an excitation process involving three or more photons. This conjecture is further confirmed by the observation of the super-quadratic dependence of the fluorescence intensity on the excitation power. Further work is required to spectroscopically identify these emitting species. This study demonstrates the use of multiphoton excitation microscopy for functional imaging of the metabolic states of in vivo human skin cells. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 PMID:9168018

  2. Effect of pulse intensity distributions on fragment internal energy in the infrared multiphoton dissociation of vinyl

    E-print Network

    dissociation of vinyl cyanide John S. McKillop, Robert J. Gordon,a) and Richard N. Zare Department of the rovibra- tional energy distributions of fragmentsl formed in the infrared multiphoton dissociation (IRMPD rotational temperatures on the laser intensity and (2) a statistical distribution in dissociation lifetimes

  3. Near-infrared femtosecond laser machining initiated by ultraviolet multiphoton ionization

    E-print Network

    Van Stryland, Eric

    wave ultraviolet-laser sintering of ZnO and TiO2 nanoparticle thin films at low laser powers J. Appl. Phys. 113, 044310 (2013) Controlling laser emission by selecting crystal orientation Appl. Phys. LettNear-infrared femtosecond laser machining initiated by ultraviolet multiphoton ionization X. Yu, Q

  4. Dynamics of multiphoton excitation and quantum diffusion in Rydberg atoms

    E-print Network

    Chu, Shih-I; Wang, Kwanghsi

    1989-02-15

    and ?q the quantum delocalization threshold), large discrepancies exist between 1D and 2D results. It is found that the 1D model seriously underestimates the ionization probabilities and, more importantly, the dominant channels for Rydberg atom excitation...

  5. 3D super-resolved in vitro multiphoton microscopy by saturation of excitation

    E-print Network

    Nguyen, Anh Dung; Bouwens, Arno; Vanholsbeeck, Frédérique; Egrise, Dominique; Van Simayes, Gaetan; Emplit, Philippe; Goldman, Serge; Gorza, Simon-Pierre

    2015-01-01

    We demonstrate a significant resolution enhancement beyond the conventional limit in multiphoton microscopy (MPM) using saturated excitation of fluorescence. Our technique achieves super-resolved imaging by temporally modulating the excitation laser-intensity and demodulating the higher harmonics from the saturated fluorescence signal. The improvement of the lateral and axial resolutions is measured on a sample of fluorescent microspheres. While the third harmonic already provides an enhanced resolution, we show that a further improvement can be obtained with an appropriate linear combination of the demodulated harmonics. Finally, we present in vitro imaging of fluorescent microspheres incorporated in HeLa cells to show that this technique performs well in biological samples.

  6. Multiphoton imaging of quantum dot bioconjugates in cultured cells following Nd:YLF laser excitation

    NASA Astrophysics Data System (ADS)

    Serrano, Elba E.; Knight, V. B.

    2005-04-01

    Quantum dot bioconjugates offer unprecedented opportunities for monitoring biological processes and molecular interactions in cells, tissues, and organs. We are interested in developing applications that permit investigation of physiological processes and cytoskeletal organization in live cells, and allow imaging of complex organs, such as the auditory and vestibular sensory structures of the inner ear. Multiphoton microscopy is a powerful technique for acquiring images from deep within a sample while reducing phototoxic effects of laser light exposure on cells. Previous studies have established that a solid-state Nd:YLF laser can be used to acquire two-photon and three-photon images from live cells while minimizing phototoxic side effects (Wokosin et al., 1996, Bioimaging, 4:208-214; Squirrell et al., 1999, Nature Biotechnology, 8:763-767). We present here the results of experiments using an all-solid-state Nd:YLF 1047 nm femtosecond laser (Microlase DPM1000) source to excite quantum dot bioconjugates. Cells were labeled with Qdot (Quantum Dot Corporation) bioconjugates or with Alexa Fluor (Molecular Probes) bioconjugates and then imaged with a BioRad 1024 confocal microscope configured for multiphoton imaging using internal or external (non-descanned) detectors. Results demonstrate that the Nd:YLF laser can be used to stimulate fluorescence emission of quantum dots and Alexa Fluor bioconjugates in cultured amphibian (Xenopus) and mammalian (rat, chinese hamster) cells. We conclude that the Nd:YLF laser is a viable excitation source that extends the applicability of quantum dots for investigation of biological processes using multiphoton microscopy.

  7. Nonlinear structured-illumination enhanced temporal focusing multiphoton excitation microscopy with a digital micromirror device

    PubMed Central

    Cheng, Li-Chung; Lien, Chi-Hsiang; Da Sie, Yong; Hu, Yvonne Yuling; Lin, Chun-Yu; Chien, Fan-Ching; Xu, Chris; Dong, Chen Yuan; Chen, Shean-Jen

    2014-01-01

    In this study, the light diffraction of temporal focusing multiphoton excitation microscopy (TFMPEM) and the excitation patterning of nonlinear structured-illumination microscopy (NSIM) can be simultaneously and accurately implemented via a single high-resolution digital micromirror device. The lateral and axial spatial resolutions of the TFMPEM are remarkably improved through the second-order NSIM and projected structured light, respectively. The experimental results demonstrate that the lateral and axial resolutions are enhanced from 397 nm to 168 nm (2.4-fold) and from 2.33 ?m to 1.22 ?m (1.9-fold), respectively, in full width at the half maximum. Furthermore, a three-dimensionally rendered image of a cytoskeleton cell featuring ~25 nm microtubules is improved, with other microtubules at a distance near the lateral resolution of 168 nm also able to be distinguished. PMID:25136483

  8. Multi-photon excitation and ionization cross sections in atomic oxygen

    SciTech Connect

    McGuire, E.J.

    1985-01-01

    Calculations are presented on a variety of multi-photon excitation and ionization cross sections in oxygen. The regimes of cross sections discussed are: (1) 2-photon excitation to the bound (2p)/sup 3/ /sup 4/S (nl) levels; (2) 2-photon excitation to the autoionizing (2p)/sup 3/ /sup 2/D (3p) and (2p)/sup 3/ /sup 2/P (3p) levels; (3) excitation of the (2p)/sup 4/ /sup 1/D and /sup 1/S levels by both 1-photon excitation on forbidden transitions and 2-photon excitations; (4) 1-photon photoionization of the (2p)/sup 3/ /sup 4/S (3s) /sup 3/S and (2p)/sup 3/ /sup 4/S (3p) /sup 3/P levels; and (5) 3-photon nonresonant ionization with the (2p)/sup 3/ /sup 4/S (3p) /sup 3/P level as an intermediate resonance. 5 refs., 3 figs., 2 tabs.

  9. THE INTRAMOLECULAR VIBRATIONAL ENERGY DISTRIBUTION OF INFRARED MULTIPHOTON EXCITED MOLECULES

    E-print Network

    Mazur, Eric

    taught me not only how to work, but also how to play. His insistence on quality and efficiency has shaped in the work presented in this thesis. They have helped me not only in achieving academic goals, but also my work style, as well as my ideas on being a scientist. I cherish the days I worked with him. It has

  10. Influence of multi-photon excitation on the atomic above-threshold ionization

    NASA Astrophysics Data System (ADS)

    Tian, Yuan-Ye; Wang, Chun-Cheng; Li, Su-Yu; Guo, Fu-Ming; Ding, Da-Jun; Wim-G, Roeterdink; Chen, Ji-Gen; Zeng, Si-Liang; Liu, Xue-Shen; Yang, Yu-Jun

    2015-04-01

    Using the time-dependent pseudo-spectral scheme, we solve the time-dependent Schrödinger equation of a hydrogen-like atom in a strong laser field in momentum space. The intensity-resolved photoelectron energy spectrum in above-threshold ionization is obtained and further analyzed. We find that with the increase of the laser intensity, the above-threshold ionization emission spectrum exhibits periodic resonance structure. By analyzing the population of atomic bound states, we find that it is the multi-photon excitation of bound state that leads to the occurrence of this phenomenon, which is in fairly good agreement with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2013CB922200), the National Natural Science Foundation of China (Grants Nos. 11274141, 11034003, 11304116, 11274001, and 11247024), and the Jilin Provincial Research Foundation for Basic Research, China (Grant No. 20140101168JC).

  11. Nonperturbative analysis of the two-level atom: Applications to multiphoton excitation

    SciTech Connect

    Duvall, R.E.; Valeo, E.J.; Oberman, C.R.

    1987-08-01

    Selective excitation in an atomic system subjected to a slowly varying external electromagnetic field is studied using a two-level model. Time evolution of the system is found using an approach which is nonperturbative in the field strength. There is no constraint to small values of the applied field, that is, the field (in appropriate energy units) need not be small compared to the difference in energies of the two levels. Rather, we prey upon the fact that the situation of interest to us is where the frequency of the exciting field is small compared to the frequency associated with the level difference. Transition probabilities and resonance conditions are found which circumscribe both the large and small field limits. In the weak field limit the previous results of high-order perturbation theory are readily recovered. For a monochromatic field the characteristic features of resonance excitation at high harmonic number of the applied field are (a) extremely narrow resonance widths and (b) shifts in resonance positions which are strong functions of field intensity. Because of this sensitivity, we are able to demonstrate that when slow temporal evolution of the field amplitude is taken into account (e.g., due to finite pulse duration) the appropriate mean excitation rate is that due to the uncorrelated contribution of many resonances. The results of this analysis are used to estimate excitation rates in a specific atomic system, Cd/sup 12 +/, which are then compared to multiphoton ionization rates. Our calculations suggest that the ionization rate exceeds the excitation rate by several orders of magnitude. 15 refs., 3 figs.

  12. Specific local induction of DNA strand breaks by infrared multi-photon absorption

    PubMed Central

    Träutlein, D.; Deibler, M.; Leitenstorfer, A.; Ferrando-May, E.

    2010-01-01

    Highly confined DNA damage by femtosecond laser irradiation currently arises as a powerful tool to understand DNA repair in live cells as a function of space and time. However, the specificity with respect to damage type is limited. Here, we present an irradiation procedure based on a widely tunable Er/Yb : fiber femtosecond laser source that favors the formation of DNA strand breaks over that of UV photoproducts by more than one order of magnitude. We explain this selectivity with the different power dependence of the reactions generating strand breaks, mainly involving reactive radical intermediates, and the direct photochemical process leading to UV-photoproducts. Thus, localized multi-photon excitation with a wavelength longer than 1 µm allows for the selective production of DNA strand breaks at sub-micrometer spatial resolution in the absence of photosensitizers. PMID:19906733

  13. Ultrafast multiphoton pump-probe photoemission excitation pathways in rutile TiO2(110 )

    NASA Astrophysics Data System (ADS)

    Argondizzo, Adam; Cui, Xuefeng; Wang, Cong; Sun, Huijuan; Shang, Honghui; Zhao, Jin; Petek, Hrvoje

    2015-04-01

    We investigate the spectroscopy and photoinduced electron dynamics within the conduction band of reduced rutile Ti O2(110 ) surface by multiphoton photoemission (mPP ) spectroscopy with wavelength tunable ultrafast (˜20 fs ) laser pulse excitation. Tuning the mPP photon excitation energy between 2.9 and 4.6 eV reveals a nearly degenerate pair of new unoccupied states located at 2.73 ±0.05 and 2.85 ±0.05 eV above the Fermi level, which can be analyzed through the polarization and sample azimuthal orientation dependence of the mPP spectra. Based on the calculated electronic structure and optical transition moments, as well as related spectroscopic evidence, we assign these resonances to transitions between Ti 3 d bands of nominally t2 g and eg symmetry, which are split by crystal field. The initial states for the optical transition are the reduced T i3 + states of t2 g symmetry populated by formation oxygen vacancy defects, which exist within the band gap of Ti O2 . Furthermore, we studied the electron dynamics within the conduction band of Ti O2 by three-dimensional time-resolved pump-probe interferometric mPP measurements. The spectroscopic and time-resolved studies reveal competition between 2PP and 3PP processes where the t2 g-eg transitions in the 2PP process saturate, and are overtaken by the 3PP process initiated by the band-gap excitation from the valence band of Ti O2 .

  14. Cell Adhesion on Micro-Structured Fibronectin Gradients Fabricated by Multiphoton Excited Photochemistry

    PubMed Central

    Chen, Xiyi; Su, Yuan-Deng; Ajeti, Visar; Chen, Shean-Jen; Campagnola, Paul J.

    2013-01-01

    Concentration gradients of ECM proteins play active roles in many areas of cell biology including wound healing and metastasis. They may also form the basis of tissue engineering scaffolds, as these can direct cell adhesion and migration and promote new matrix synthesis. To better understand cell–matrix interactions on attractive gradients, we have used multiphoton excited (MPE) photochemistry to fabricate covalently linked micro-structured gradients from fibronectin (FN). The gradient design is comprised of a parallel series of individual linear gradients with overall dimensions of approximately 800 × 800 ?m, where a linear dynamic range of nearly 10-fold in concentration was achieved. The adhesion dynamics of 3T3 fibroblasts were investigated, where the cell morphology and actin cytoskeleton became increasingly elongated and aligned with the direction of the gradient at increasing protein concentration. Moreover, the cell morphologies are distinct when adhered to regions of differing FN concentration but with similar topography. These results show that the fabrication approach allows investigating the roles of contact guidance and ECM cues on the cell–matrix interactions. We suggest this design overcomes some of the limitations with other fabrication methods, especially in terms of 3D patterning capabilities, and will serve as a new tool to study cell–matrix interactions. PMID:23710258

  15. Laser-driven nonlinear cluster dynamics: from single- and multiphoton excitations to the strong-field domain

    E-print Network

    Fennel, Th; Tiggesbaumker, J; Reinhard, P -G; Dinh, P M; Suraud, E

    2009-01-01

    Laser excitation of nanometer-sized atomic and molecular clusters offers insight into complex many-particle dynamics from several perspectives. Whereas weak laser fields allow the analysis of photoionization, excited-state relaxation, and structural modifications on these finite quantum systems, violent collective electron motion and Coulomb explosion can be explored with intense laser pulses. This review provides an overview of key phenomena arising from laser-cluster interactions with focus on nonlinear optical excitations and discusses underlying processes according to the current understanding. A brief general survey covers basic cluster properties and excitation mechanisms relevant for laser-driven cluster dynamics. Then, after an excursion in theoretical and experimental methods, results for single- and multiphoton excitations are reviewed with emphasis on signatures from time- and angular-resolved photoemission. The broad spectrum of phenomena arising from clusters in strong fields is closely related t...

  16. Nonperturbative methods in the problem of multiphoton excitation of atom by squeezed light

    NASA Technical Reports Server (NTRS)

    Belousov, A. V.; Kovarsky, V. A.

    1993-01-01

    Multiphoton detectors for the strong squeezed light vacuum are considered. The result is compared with the perturbation theory. It is shown that as the degree of squeezing is increased the statistical factor decreases.

  17. Multiphoton tomography for tissue engineering

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2008-02-01

    Femtosecond laser multiphoton tomography has been employed in the field of tissue engineering to perform 3D high-resolution imaging of the extracellular matrix proteins elastin and collagen as well as of living cells without any fixation, slicing, and staining. Near infrared 80 MHz picojoule femtosecond laser pulses are able to excite the endogenous fluorophores NAD(P)H, flavoproteins, melanin, and elastin via a non-resonant two-photon excitation process. In addition, collagen can be imaged by second harmonic generation. Using a two-PMT detection system, the ratio of elastin to collagen was determined during optical sectioning. A high submicron spatial resolution and 50 picosecond temporal resolution was achieved using galvoscan mirrors and piezodriven focusing optics as well as a time-correlated single photon counting module with a fast microchannel plate detector and fast photomultipliers. Multiphoton tomography has been used to optimize the tissue engineering of heart valves and vessels in bioincubators as well as to characterize artificial skin. Stem cell characterization and manipulation are of major interest for the field of tissue engineering. Using the novel sub-20 femtosecond multiphoton nanoprocessing laser microscope FemtOgene, the differentiation of human stem cells within spheroids has been in vivo monitored with submicron resolution. In addition, the efficient targeted transfection has been demonstrated. Clinical studies on the interaction of tissue-engineered products with the natural tissue environment can be performed with in vivo multiphoton tomograph DermaInspect.

  18. Multiphoton imaging of cardiovascular structures

    NASA Astrophysics Data System (ADS)

    Schenke-Layland, Katja; Opitz, Florian; Riemann, Iris; Stock, Ulrich A.; Konig, Karsten

    2004-09-01

    Near infrared (NIR) femtosecond laser imaging systems represent a novel and very promising diagnostic technology for non-invasive cross-sectional analysis of living biological tissues. In this study 3D multiphoton imaging with submicron resolution has been performed for non-invasive analysis of living native and tissue-engineered (TE) heart valves and blood vessels. High-resolution autofluorescence and second harmonic generation (SHG) images of collagenous structures and elastic fibers were demonstrated using multiphoton excitation at two different wavelengths. Non-invasive optical sections have been obtained without the need of staining or embedding. The quality of the resulting three-dimensional images allowed exact differentiation between collagenous structures and elastic fibers. These experimental results are very encouraging for NIR femtosecond laser scanning microscopy as a useful tool for future non-destructive monitoring and characterization of vital and intact TE cardiovascular structures.

  19. Carcinogenic damage to deoxyribonucleic acid is induced by near-infrared laser pulses in multiphoton microscopy via combination of two- and three-photon absorption

    NASA Astrophysics Data System (ADS)

    Nadiarnykh, Oleg; Thomas, Giju; Van Voskuilen, Johan; Sterenborg, Henricus J. C. M.; Gerritsen, Hans C.

    2012-11-01

    Nonlinear optical imaging modalities (multiphoton excited fluorescence, second and third harmonic generation) applied in vivo are increasingly promising for clinical diagnostics and the monitoring of cancer and other disorders, as they can probe tissue with high diffraction-limited resolution at near-infrared (IR) wavelengths. However, high peak intensity of femtosecond laser pulses required for two-photon processes causes formation of cyclobutane-pyrimidine-dimers (CPDs) in cellular deoxyribonucleic acid (DNA) similar to damage from exposure to solar ultraviolet (UV) light. Inaccurate repair of subsequent mutations increases the risk of carcinogenesis. In this study, we investigate CPD damage that results in Chinese hamster ovary cells in vitro from imaging them with two-photon excited autofluorescence. The CPD levels are quantified by immunofluorescent staining. We further evaluate the extent of CPD damage with respect to varied wavelength, pulse width at focal plane, and pixel dwell time as compared with more pronounced damage from UV sources. While CPD damage has been expected to result from three-photon absorption, our results reveal that CPDs are induced by competing two- and three-photon absorption processes, where the former accesses UVA absorption band. This finding is independently confirmed by nonlinear dependencies of damage on laser power, wavelength, and pulse width.

  20. COMPACT NON-CONTACT TOTAL EMISSION DETECTION FOR IN-VIVO MULTI-PHOTON EXCITATION MICROSCOPY

    PubMed Central

    Glancy, Brian; Karamzadeh, Nader S.; Gandjbakhche, Amir H.; Redford, Glen; Kilborn, Karl; Knutson, Jay R.; Balaban, Robert S.

    2014-01-01

    Summary We describe a compact, non-contact design for a Total Emission Detection (c-TED) system for intra-vital multi-photon imaging. To conform to a standard upright two-photon microscope design, this system uses a parabolic mirror surrounding a standard microscope objective in concert with an optical path that does not interfere with normal microscope operation. The non-contact design of this device allows for maximal light collection without disrupting the physiology of the specimen being examined. Tests were conducted on exposed tissues in live animals to examine the emission collection enhancement of the c-TED device compared to heavily optimized objective-based emission collection. The best light collection enhancement was seen from murine fat (5×-2× gains as a function of depth), while murine skeletal muscle and rat kidney showed gains of over two and just under two-fold near the surface, respectively. Gains decreased with imaging depth (particularly in the kidney). Zebrafish imaging on a reflective substrate showed close to a two-fold gain throughout the entire volume of an intact embryo (approximately 150 ?m deep). Direct measurement of bleaching rates confirmed that the lower laser powers (enabled by greater light collection efficiency) yielded reduced photobleaching in vivo. The potential benefits of increased light collection in terms of speed of imaging and reduced photo-damage, as well as the applicability of this device to other multi-photon imaging methods is discussed. PMID:24251437

  1. Simulation-based investigation of the three-dimensional distribution of fluorescence and photobleaching in multi-photon excited samples

    NASA Astrophysics Data System (ADS)

    Juhász, Imre B.; Csurgay, Árpád. I.

    2014-05-01

    We present a numerical study on the spatial distribution of fluorescence and photobleaching occurring in samples subject to multi-photon excitation. We developed a simulation model and implemented a simulator program. Its quantitative predictions can help to find the optimal operating parameters (such as laser power, pulse length, pulse repetition rate) of the two-photon microscope to reach higher image quality, to reduce undesired photobleaching, and to pave the way for optimized photoswitching-based super-resolution imaging. Conversely, the simulator might also be useful when photodynamic parameters are searched for. Furthermore, such simulations can promote the evaluation of the results of other fluorescence-based techniques [e.g. fluorescence recovery after photobleaching (FRAP) measurements]. The photodynamic model of the fluorophore contains a ground state, an excited state, a triplet state, and several photobleached states; the state transitions are characterized by absorption cross sections and lifetimes. The sample is modeled as a fluorophore solution divided into cubic cells among which diffusion takes place. The illumination is simulated as a focused laser pulse train described by a pulsed Gaussian beam. As a demonstration of the capabilities of the simulator, an example is presented that reveals the spatial distribution of photon emission in the sample investigated by a two-photon microscope in the case of different laser and photobleaching parameters, assuming one-photon absorption induced photobleaching. The simulation demonstrates quantitatively how photobleaching affects the spatial distribution of fluorescence and the resolution of the microscope.

  2. Multi-photon ionization and fragmentation of uracil: Neutral excited-state ring opening and hydration effects

    SciTech Connect

    Barc, B.; Ryszka, M.; Spurrell, J.; Dampc, M.; Limão-Vieira, P.; Parajuli, R.; Mason, N. J.; Eden, S.

    2013-12-28

    Multi-photon ionization (MPI) of the RNA base uracil has been studied in the wavelength range 220–270 nm, coinciding with excitation to the S{sub 2}(??*) state. A fragment ion at m/z = 84 was produced by 2-photon absorption at wavelengths ?232 nm and assigned to C{sub 3}H{sub 4}N{sub 2}O{sup +} following CO abstraction. This ion has not been observed in alternative dissociative ionization processes (notably electron impact) and its threshold is close to recent calculations of the minimum activation energy for a ring opening conical intersection to a ?(n-?)?* closed shell state. Moreover, the predicted ring opening transition leaves a CO group at one end of the isomer, apparently vulnerable to abstraction. An MPI mass spectrum of uracil-water clusters is presented for the first time and compared with an equivalent dry measurement. Hydration enhances certain fragment ion pathways (particularly C{sub 3}H{sub 3}NO{sup +}) but represses C{sub 3}H{sub 4}N{sub 2}O{sup +} production. This indicates that hydrogen bonding to water stabilizes uracil with respect to neutral excited-state ring opening.

  3. Multi-photon ionization and fragmentation of uracil: Neutral excited-state ring opening and hydration effects

    NASA Astrophysics Data System (ADS)

    Barc, B.; Ryszka, M.; Spurrell, J.; Dampc, M.; Limão-Vieira, P.; Parajuli, R.; Mason, N. J.; Eden, S.

    2013-12-01

    Multi-photon ionization (MPI) of the RNA base uracil has been studied in the wavelength range 220-270 nm, coinciding with excitation to the S2(??*) state. A fragment ion at m/z = 84 was produced by 2-photon absorption at wavelengths ?232 nm and assigned to C3H4N2O+ following CO abstraction. This ion has not been observed in alternative dissociative ionization processes (notably electron impact) and its threshold is close to recent calculations of the minimum activation energy for a ring opening conical intersection to a ?(n-?)?* closed shell state. Moreover, the predicted ring opening transition leaves a CO group at one end of the isomer, apparently vulnerable to abstraction. An MPI mass spectrum of uracil-water clusters is presented for the first time and compared with an equivalent dry measurement. Hydration enhances certain fragment ion pathways (particularly C3H3NO+) but represses C3H4N2O+ production. This indicates that hydrogen bonding to water stabilizes uracil with respect to neutral excited-state ring opening.

  4. Cascade Dissociations of Peptide Cation-Radicals. Part2. Infrared Multiphoton Dissociation and Mechanistic Studies of z-Ions from Pentapeptides

    PubMed Central

    Ledvina, Aaron R.; Chung, Thomas W.; Hui, Renjie; Coon, Joshua J.

    2013-01-01

    Dissociations of z4 ions from pentapeptides AAXAR, where X = H, Y, F, W, and V, produce dominant z2 ions that account for >50% of the fragment ion intensity. The dissociation has been studied in detail by experiment and theory and found to involve several isomerization and bond-breaking steps. Isomerizations in z4 ions proceed by amide transcis rotations followed by radical-induced transfer of a ?-hydrogen atom from the side chain, forming stable C? radical intermediates. These undergo rate-determining cleavage of the C?—CO bond at the X residue followed by loss of the neutral AX fragment, forming x2 intermediates. The latter were detected by energy-resolved resonant excitation collision-activated dissociation (CAD) and infrared multiphoton dissociation (IRMPD) experiments. The x2 intermediates undergo facile loss of HNCO to form z2 fragment ions, as also confirmed by energy-resolved CAD and IRMPD MS4 experiments. The loss of HNCO from the x2 ion from AAHWR is kinetically hampered by the Trp residue that traps the OCNH radical group in a cyclic intermediate. PMID:22669762

  5. Multi-photon excited coherent random laser emission in ZnO powders

    NASA Astrophysics Data System (ADS)

    Tolentino Dominguez, Christian; Gomes, Maria De A.; Macedo, Zélia S.; de Araújo, Cid B.; Gomes, Anderson S. L.

    2014-11-01

    We report the observation and analysis of anti-Stokes coherent random laser (RL) emission from zinc oxide (ZnO) powders excited by one-, two- or three-photon femtosecond laser radiation. The ZnO powders were produced via a novel proteic sol-gel, low-cost and environmentally friendly route using coconut water in the polymerization step of the metal precursor. One- and two-photon excitation at 354 nm and 710 nm, respectively, generated single-band emissions centred at about 387 nm. For three-photon excitation, the emission spectra showed a strong ultraviolet (UV) band (380-396 nm) attributed to direct three-photon absorption from the valence band to the conduction band. The presence of an intensity threshold and a bandwidth narrowing of the UV band from about 20 to 4 nm are clear evidence of RL action. The observation of multiple sub-nanometre narrow peaks in the emission spectra for excitation above the RL threshold is consistent with random lasing by coherent feedback.

  6. Infrared multiphoton dissociation in two-channel systems. Pulse-duration effects

    SciTech Connect

    Brenner, D.M.

    1982-01-07

    Both ethyl vinyl ether (EVE) and dihydrofuran (DHF) dissociate by two reaction channels which differ by approx.25 kcal mol/sup -1/ in activation energies. In DHF, the branching ratio between these channels produced by IR-multiphoton-induced dissociation shows no power dependence, by contrast to previous work with EVE. In view of the similarity of the Arrhenius activation parameters in the two systems, this is surprising. Therefore, a comparison of the peak-power dependence of the branching ratio in the two systems has been studied at h..nu..CO/sub 2/ = 1076 cm/sup -1/ where the average energy absorbed is the same in both molecules. Results on the power dependence of branching ratio and yield suggest that differences in absorption coefficients (pumping rates) in the quasicontinuum may account for the differences in power dependence.

  7. VIBRATIONALLY EXCITED HCN IN THE LUMINOUS INFRARED GALAXY NGC 4418

    SciTech Connect

    Sakamoto, Kazushi; Aalto, Susanne; Evans, Aaron S.; Wiedner, Martina C.; Wilner, David J.

    2010-12-20

    Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of T{sub vib} {approx} 230 K between the vibrational ground and excited (v{sub 2} = 1) states. This excitation is most likely due to infrared radiation. At this high vibrational temperature the path through the v{sub 2} = 1 state must have a strong impact on the rotational excitation in the vibrational ground level, although it may not be dominant for all rotational levels. Our observations also revealed nearly confusion-limited lines of CO, HCN, HCO{sup +}, H{sup 13}CN, HC{sup 15}N, CS, N{sub 2}H{sup +}, and HC{sub 3}N at {lambda} {approx} 1 mm. Their relative intensities may also be affected by the infrared pumping.

  8. Chaos in a semiclassical model of multiphoton excitation of spherical top molecules

    SciTech Connect

    Galbraith, H.W.; Ackerhalt, J.R.; Milonni, P.W.

    1983-01-01

    We study the dynamical effects of vibration-rotation coupling in multiple photon excitation at lowest order. Our molecular model is the simplest possible: that of an oscillator (triply degenerate) and uncoupled rigid rotor. The molecule-field interactions introduce a vibration-rotation nonlinearity which gives rise to nonconservation of the molecular angular momentum and in some instances consequent chaotic dynamics. The chaos leads to incoherence (widely seen in experiments) in the time dependence of the photon absorption and is not treatable in an additive way as inhomogeneous broadening. The nonconservation of the molecular angular momentum is due to the development with time of the molecular vibrational angular momentum. The degree of chaotic behavior is found to depend upon the relative size of the vibrational to pure rotational angular momenta as the excitation progresses, i.e., when vibrational angular momentum exceeds the pure rotational angular momentum we find chaos, conversely when J/sub 0/ is quite large the motion is gyroscopically stabilized and quasiperiodic. Therefore the suggested cold experiments are perhaps not so desirable.

  9. Infrared imaging results of an excited planar jet

    SciTech Connect

    Farrington, R.B.

    1991-12-01

    Planar jets are used for many applications including heating, cooling, and ventilation. Generally such a jet is designed to provide good mixing within an enclosure. In building applications, the jet provides both thermal comfort and adequate indoor air quality. Increased mixing rates may lead to lower short-circuiting of conditioned air, elimination of dead zones within the occupied zone, reduced energy costs, increased occupant comfort, and higher indoor air quality. This paper discusses using an infrared imaging system to show the effect of excitation of a jet on the spread angle and on the jet mixing efficiency. Infrared imaging captures a large number of data points in real time (over 50,000 data points per image) providing significant advantages over single-point measurements. We used a screen mesh with a time constant of approximately 0.3 seconds as a target for the infrared camera to detect temperature variations in the jet. The infrared images show increased jet spread due to excitation of the jet. Digital data reduction and analysis show change in jet isotherms and quantify the increased mixing caused by excitation. 17 refs., 20 figs.

  10. Water splitting by infrared femtosecond laser excitation of surface plasmon

    NASA Astrophysics Data System (ADS)

    Klett, Charles; Mirica, Jean-Philippe; Hergott, Jean-François; Lepetit, Fabien; Renault, Jean-Philippe

    2013-02-01

    Gold nanoparticles supported on soda-lime glass exhibit a photochemical water splitting activity under infrared femtosecond laser excitation. Both H2 and hydroxyl radicals productions were characterized. The hydroxyl radicals production mechanism was identified by comparison with three prototypal mechanisms, photoionization of organic compound in the UV, VUV dissociation of water and water gamma radiolysis. The mechanisms involved in the case of laser femtosecond seem to be water ionization events occurring at distance from the gold particles.

  11. Multiphoton excitation evoked chromophore-

    E-print Network

    Cai, Long

    in conjunction with EGFP. Experiments were performed on HeLa cells stably transfected with cDNA encoding Cx431 Noninvasive, straightforward methods to inactivate selected proteins in living cells with high photodamage in living mammalian cells. Now that human genome data have become available, it is increasingly

  12. SPONTANEOUS RAMAN AND COHERENT ANTI-STOKES RAMAN SPECTROSCOPY OF INFRARED MULTIPHOTON EXCITED MOLECULES

    E-print Network

    Mazur, Eric

    and rigorousness in scientific research. It has been a pleasure to collaborate with Professor Mary Shultz. Her Street, Somerville was indispensable during the past five years. My landlady Margaret Waller taught me

  13. Formation of infrared solitons in graphene ensemble under Raman excitation

    NASA Astrophysics Data System (ADS)

    Ding, Chunling; Yu, Rong; Yang, Xiaoxue; Zhang, Duo; Huang, Mingju

    2015-11-01

    The formation of infrared solitons in graphene under Raman excitation is investigated using density-matrix approach. We find that the unique band structure and selection rules for the optical transitions near the Dirac point can result in extremely strong optical nonlinearity. Theoretical investigations with the aid of slowly varying envelope approximation and perturbation theory clearly indicate the existence of bright and dark solitons in Landau-quantized graphene. Actually, the formation of spatial soliton in such a material is the consequence of the balance between nonlinear effects and the dispersion properties. Also, the corresponding carrier frequency is tunable in the infrared range. These results can make us know better the crossover between optical solitons and graphene metamaterials. The predicted nonlinear optical effect in graphene may provide a new possibility for designing high-fidelity graphene-based information processing device.

  14. Electrically excited, localized infrared emission from single carbon nanotubes.

    PubMed

    Freitag, Marcus; Tsang, James C; Kirtley, John; Carlsen, Autumn; Chen, Jia; Troeman, Aico; Hilgenkamp, Hans; Avouris, Phaedon

    2006-07-01

    Carbon nanotube field-effect transistors (CNTFETs) produce band gap derived infrared emission under both ambipolar and unipolar transport conditions. We demonstrate here that heterogeneities/defects in the local environment of a CNTFET perturb the local potentials and, as a result, the characteristic bias dependent motion of the ambipolar light emission. Such defects can also introduce localized infrared emission due to impact excitation by carriers accelerated by a voltage drop at the defect. The correlation of the change in the motion of the ambipolarlight emission and of the stationary electroluminescence with the electrical characteristics of the CNTFETs shows that stationaryelectroluminescence can identify "environmental defects" in carbon nanotubes and help evaluate their influence on electrical transport and device operation. A number of different defects are studied involving local dielectric environment changes (partially polymer-covered nanotubes), nanotube-nanotube contacts in looped nanotubes, and nanotube segments close to the electronic contacts. Random defects due to local charging are also observed. PMID:16834423

  15. Infrared multiphoton induced isomerization and dissociation of FCN, ClCN, and BrCN in liquid Ar: A classical simulation study

    SciTech Connect

    Zhang Ming; Gong Jiangbin; Ma Ao; Rice, Stuart A.

    2007-10-14

    We report the results of classical mechanics simulations of infrared multiphoton induced control of isomerization of FCN, ClCN, and BrCN in liquid Ar, using ab initio potential energy and dipole moment surfaces for the XCN molecules. The field induced isomerization and fragmentation dynamics of these molecules are found to be different from that of HCN in liquid Ar. In particular, the scheme that provides complete controlled conversion of HCN to CNH in liquid Ar fails to generate complete conversion of XCN to CNX in liquid Ar for X=F,Cl,Br. It is suggested that the sources of the differences in behavior arise from differences in the spectra of vibrational nonlinear resonances in HCN and XCN and to the occurrence of monodromy in the dynamics of the XCN molecules.

  16. Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide

    E-print Network

    Julian Juhi-Lian Ting

    1998-07-15

    Within a one-dimensional semi-classical model with a Morse potential the possibility of infrared multi-photon dissociation of vibrationally excited nitrogen oxide was studied. The dissociation thresholds of typical driving forces and couplings were found to be similar, which indicates that the results were robust to variations of the potential and of the definition of dissociation rate. PACS: 42.50.Hz, 33.80.Wz

  17. Quantum dot infrared photodetector enhanced by surface plasma wave excitation.

    PubMed

    Lee, S C; Krishna, S; Brueck, S R J

    2009-12-01

    Up to a thirty-fold detectivity enhancement is achieved for an InAs quantum dot infrared photodetector (QDIP) by the excitation of surface plasma waves (SPWs) using a metal photonic crystal (MPC) integrated on top of the detector absorption region. The MPC is a 100 nm-thick gold film perforated with a 3.6 microm period square array of circular holes. A bare QDIP shows a bias-tunable broadband response from approximately 6 to 10 microm associated with the quantum confined Stark (QCS) effect. On the other hand, an MPC-integrated QDIP exhibits a dominant peak at 11.3 microm with a approximately 1 microm full width at half maximum and the highly enhanced detectivity at the bias polarity optimized for long wavelength. This is very different from the photoresponse of the bare QDIP but fully consistent with the direct coupling of the QDs in the detector absorption region to the SPWs excited at the MPC/detector interface by incident photons. The SPW resonance wavelength, lambda, for the smallest coupling wavevector of the array in the MPC is close to 11.3 microm. The response also shows other SPW-coupled peaks: a significant peak at 8.1 microm (approximately lambda/radical2) and noticeable peaks at 5.8 microm (approximately lambda/2) and 5.4 microm (approximately lambda/ radical5) which correspond to higher-order coupling wavevectors. For the opposite bias, the MPC-integrated QDIP shows the highest response at 8.1 microm, providing a dramatic voltage tunability that is associated with QCS effect. SPWs propagate with TM (x, z) polarization along the MPC/detector interface. The enhanced detectivity is explained by these characteristics which increase both the effective absorption cross section with propagation and the interaction strength with TM polarization in the coupling to the QDs. Simulations show good qualitative agreement with the observed spectral behavior. PMID:20052244

  18. Clinical multiphoton FLIM tomography

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2012-03-01

    This paper gives an overview on current clinical high resolution multiphoton fluorescence lifetime imaging in volunteers and patients. Fluorescence lifetime imaging (FLIM) in Life Sciences was introduced in Jena/Germany in 1988/89 based on a ZEISS confocal picosecond dye laser scanning microscope equipped with a single photon counting unit. The porphyrin distribution in living cells and living tumor-bearing mice was studied with high spatial, temporal, and spectral resolution. Ten years later, time-gated cameras were employed to detect dental caries in volunteers based on one-photon excitation of autofluorescent bacteria with long fluorescence lifetimes. Nowadays, one-photon FLIM based on picosecond VIS laser diodes are used to study ocular diseases in humans. Already one decade ago, first clinical twophoton FLIM images in humans were taken with the certified clinical multiphoton femtosecond laser tomograph DermaInspectTM. Multiphoton tomographs with FLIM modules are now operating in hospitals at Brisbane, Tokyo, Berlin, Paris, London, Modena and other European cities. Multiple FLIM detectors allow spectral FLIM with a temporal resolution down to 20 ps (MCP) / 250 ps (PMT) and a spectral resolution of 10 nm. Major FLIM applications include the detection of intradermal sunscreen and tattoo nanoparticles, the detection of different melanin types, the early diagnosis of dermatitis and malignant melanoma, as well as the measurement of therapeutic effects in pateints suffering from dermatitis. So far, more than 1,000 patients and volunteers have been investigated with the clinical multiphoton FLIM tomographs DermaInspectTM and MPTflexTM.

  19. Time-Resolved Resonance Raman Spectroscopy of Vibrational Populations Monitored after Electronic and Infrared Excitation

    SciTech Connect

    Werncke, W.; Kozich, V.; Dreyer, J.

    2008-11-14

    Pathways of vibrational energy flow in molecules with an intramolecular hydrogen bond are studied after intramolecular proton transfer reactions as well as after infrared excitation of the O-H stretching vibration which is coupled to this hydrogen bond.

  20. Structural characterization of arginine-vasopressin and lysine-vasopressin by Fourier- transform ion cyclotron resonance mass spectrometry and infrared multiphoton dissociation.

    PubMed

    Bianco, Giuliana; Battista, Fabio; Buchicchio, Alessandro; Amarena, Concetta G; Schmitt-Kopplin, Philippe; Guerrieri, Antonio

    2015-01-01

    Arginine-vasopressin (AVP) and lysine-vasopressin (LVP) were analyzed by reversed-phase liquid chromatography/mass spectrometry (LC-MS) using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) electrospray ionization (ESI) in the positive ion mode. LVP and AVP exhibited the protonated adduct [M+H](+) as the predominant ion at m/z 1056.43965 and at m/z 1084.44561, respectively. Infrared multiphoton dissociation (IRMPD), using a CO(2) laser source at a wavelength of 10.6 ?m, was applied to protonated vasopressin molecules. The IRMPD mass spectra presented abundant mass fragments essential for a complete structural information. Several fragment ions, shared between two target molecules, are discussed in detail. Some previously unpublished fragments were identified unambiguously utilizing the high resolution and accurate mass information provided by the FT-ICR mass spectrometer. The opening of the disulfide loop and the cleavage of the peptide bonds within the ring were observed even under low-energy fragmentation conditions. Coupling the high-performance FT-ICR mass spectrometer with IRMPD as a contemporary fragmentation technique proved to be very promising for the structural characterization of vasopressin. PMID:26307701

  1. Infrared emission from photo-excited gaseous benzene: detection with a new home-made spectrometer

    NASA Astrophysics Data System (ADS)

    Féraud, G.; Carpentier, Y.; Pino, T.; Longval, Y.; Dartois, E.; Chamaillé, T.; Vasquez, R.; Vincent, J.; Parneix, P.; Falvo, C.; Bréchignac, Ph.

    2012-02-01

    The infrared fluorescence decay and the dispersed emission spectrum are presented for gaseous benzene following 193 nm laser excitation. They were measured with FIREFLY (Fluorescence in the InfraRed from Excited FLYing molecules), a new home-made spectrometer. Redshift and redtail in the CH stretch emission spectra (3.3 ?m region) demonstrate that anharmonicity plays a key role when dealing with high internal energies, as it is the case in the interstellar medium.

  2. Three-dimensional imaging and uptake of the anticancer drug combretastatin in cell spheroids and photoisomerization in gels with multiphoton excitation

    NASA Astrophysics Data System (ADS)

    Scherer, Kathrin M.; Bisby, Roger H.; Botchway, Stanley W.; Hadfield, John A.; Haycock, John W.; Parker, Anthony W.

    2015-07-01

    The uptake of E-combretastatins, potential prodrugs of the anticancer Z-isomers, into multicellular spheroids has been imaged by intrinsic fluorescence in three dimensions using two-photon excited fluorescence lifetime imaging with 625-nm ultrafast femtosecond laser pulses. Uptake is initially observed at the spheroid periphery but extends to the spheroid core within 30 min. Using agarose gels as a three-dimensional model, the conversion of Z(trans)?E(cis) via two-photon photoisomerization is demonstrated and the location of this photochemical process may be precisely selected within the micron scale in all three dimensions at depths up to almost 2 mm. We discuss these results for enhanced tissue penetration at longer near-infrared wavelengths for cancer therapy and up to three-photon excitation and imaging using 930-nm laser pulses with suitable combretastatin analogs.

  3. Optical biopsy of liver fibrosis by use of multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Hsuan-Shu; Liu, Yuan; Chen, Hsiao-Ching; Chiou, Ling-Ling; Huang, Guan-Tarn; Lo, Wen; Dong, Chen-Yuan

    2004-11-01

    We demonstrate the application of multiphoton microscopy in diagnosing toxin- CCl4 - induced liver fibrosis in mice. Although hepatocyte autofluorescence does not vary significantly, different degrees of necrosis and stellate cell proliferation at necrotic sites in livers with fibrosis (ex vivo) can be detected easily from multiphoton-induced autofluorescence images by use of 780-nm excitation. Our result suggests that multiphoton microscopy can be developed into an effective technique for the detection and diagnosis of liver fibrosis in vivo.

  4. Multiphoton fluorescence and second harmonic generation microscopy for imaging keratoconus

    NASA Astrophysics Data System (ADS)

    Sun, Yen; Lo, Wen; Lin, Sung-Jan; Lin, Wei-Chou; Jee, Shiou-Hwa; Tan, Hsin-Yuan; Dong, Chen-Yuan

    2006-02-01

    The purpose of this study is to assess the possible application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for imaging the structural features of keratoconus cornea and to evaluate its potential as being a clinical in vivo monitoring technique. Using the near-infrared excitation source from a titanium-sapphire laser pumped by a diode-pumped, solid state (DPSS) laser system, we can induce and simultaneously acquire multiphoton autofluorescence and SHG signals from the cornea specimens with keratoconus. A home-modified commercial microscope system with specified optical components is used for optimal signal detection. Keratoconus cornea button from patient with typical clinical presentation of keratoconus was obtained at the time of penetrating keratoplasty. The specimen was also sent for the histological examination as comparison. In all samples of keratoconus, destruction of lamellar structure with altered collagen fiber orientation was observed within whole layer of the diseased stromal area. In addition, the orientation of the altered collagen fibers within the cone area shows a trend directing toward the apex of the cone, which might implicate the biomechanical response of the keratoconus stroma to the intraocular pressure. Moreover, increased autofluorescent cells were also found in the cone area, with increased density as one approaches the apical area. In conclusion, multiphoton autofluorescence and SHG microscopy non-invasively demonstrated the morphological features of keratoconus cornea, especially the structural alternations of the stromal lamellae. We believe that in the future the multiphoton microscopy can be applied in vivo as an effective, non-invasive diagnostic and monitoring technique for keratoconus.

  5. Investigating the 3.3 micron infrared fluorescence from naphthalene following ultraviolet excitation

    NASA Technical Reports Server (NTRS)

    Williams, Richard M.; Leone, Stephen R.

    1994-01-01

    Polycyclic aromatic hydrocarbon (PAH) type molecules are proposed as the carriers of the unidentified infrared (UIR) bands. Detailed studies of the 3.3 micrometer infrared emission features from naphthalene, the simplest PAH, following ultraviolet laser excitation are used in the interpretation of the 3.29 micrometer (3040 cm(sup -1)) UIR band. A time-resolved Fourier transform spectrometer is used to record the infrared emission spectrum of gas-phase naphthalene subsequent to ultraviolet excitation facilitated by an excimer laser operated at either 193 nm or 248 nm. The emission spectra differ significantly from the absorption spectrum in the same spectral region. Following 193 nm excitation the maximum in the emission profile is red-shifted 45 cm(sup -1) relative to the absorption maximum; a 25 cm(sup -1) red-shift is observed after 248 nm excitation. The red-shifting of the emission spectrum is reduced as collisional and radiative relaxation removes energy from the highly vibrationally excited molecules. Coupling between the various vibrational modes is thought to account for the differences between absorption and emission spectra. Strong visible emission is also observed following ultraviolet excitation. Visible emission may play an important role in the rate of radiative relaxation, which according to the interstellar PAH hypothesis occurs only by the slow emission of infrared photons. Studying the visible emission properties of PAH type molecules may be useful in the interpretation of the DIB's observed in absorption.

  6. High multi-photon visible upconversion emissions of Er{sup 3+} singly doped BiOCl microcrystals: A photon avalanche of Er{sup 3+} induced by 980?nm excitation

    SciTech Connect

    Li, Yongjin; Song, Zhiguo Li, Chen; Wan, Ronghua; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Yang, Yong; Zhou, Dacheng; Wang, Qi

    2013-12-02

    Under 980?nm excitation, high multi-photon upconversion (UC) emission from the {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} (green) and {sup 4}F{sub 9/2} (red) levels of Er{sup 3+} ions were observed from Er{sup 3+} singly doped BiOCl microcrystals. These high-energy excited states were populated by a three to ten photon UC process conditionally, which depended on the pump power density and the Er{sup 3+} ion doping concentration, characterizing as a hetero-looping enhanced energy transfer avalanche UC process. UC emission lifetime and Raman analysis suggest that the unusual UC phenomena are initiated by the new and intense phonon vibration modes of BiOCl lattices due to Er{sup 3+} ions doping.

  7. Stepwise multi-photon activation fluorescence reveals a new method of melanoma imaging for dermatologists

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Lian, Christine; Ma, Jie; Yu, Jingyi; Gu, Zetong; Rajadhyaksha, Milind; DiMarzio, Charles A.

    2014-02-01

    Previous research has shown that the stepwise multi-photon activated fluorescence (SMPAF) of melanin, activated by a continuous-wave (CW) mode near infrared (NIR) laser, is a low cost and reliable method of detecting melanin. SMPAF images of melanin in a mouse hair and a formalin fixed mouse melanoma were compared with conventional multiphoton fluorescence microscopy (MPFM) images and confocal reflectance microscopy (CRM) images, all of which were acquired at an excitation wavelength of 920 nm, to further prove the effectiveness of SMPAF in detecting melanin. SMPAF images add specificity for melanin detection to MPFM images and CRM images. Melanin SMPAF can be a promising technology to enable melanoma imaging for dermatologists.

  8. Noninvasive multiphoton imaging of cardiovascular structures using NIR femtosecond laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Schenke-Layland, Katja; Riemann, Iris; Stock, Ulrich A.; Konig, Karsten

    2004-07-01

    Near infrared (NIR) femtosecond laser scanning microscopy represents a novel and very promising medical diagnostic imaging technology for non-invasive cross-sectional analysis of living biological tissues. In this study multiphoton imaging has been performed to analyze the structural features of extracellular matrix (ECM) components, e.g. collagen and elastin, of living pulmonary and aortic heart valves. High-resolution autofluorescence and second harmonic generation (SHG) images of collagenous and elastic fibers were demonstrated using multifluorophore, multiphoton excitation at two different wavelengths and non-invasive optical sectioning, without the need of embedding or staining. The quality of the resulting three-dimensional images allowed exact differentiation of the ECM components. These experimental results indicated that NIR femtosecond laser scanning microscopy may prove to be a useful tool for the non-destructive monitoring and characterization of cardiovascular structures.

  9. Multiphoton Ion Imaging: A Study of Chlorine Oxide 

    E-print Network

    Freeman, Christian

    2012-04-24

    We present an analysis of the multiphoton excitation and ionization of chlorine oxide in the range 265-275nm. In particular, we identify and characterize different intermediate states, as well as product states. Additionally, the nature...

  10. Multiphoton processes: conference proceedings

    SciTech Connect

    Lambropoulos, P.; Smith, S.J.

    1984-01-01

    The chapters of this volume represent the invited papers delivered at the conference. They are arranged according to thermatic proximity beginning with atoms and continuing with molecules and surfaces. Section headings include multiphoton processes in atoms, field fluctuations and collisions in multiphoton process, and multiphoton processes in molecules and surfaces. Abstracts of individual items from the conference were prepared separately for the data base. (GHT)

  11. In vivo stepwise multi-photon activation fluorescence imaging of melanin in human skin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Gu, Zetong; Abbas, Saleh; Lowe, Jared; Sierra, Heidy; Rajadhyaksha, Milind; DiMarzio, Charles

    2014-03-01

    The stepwise multi-photon activated fluorescence (SMPAF) of melanin is a low cost and reliable method of detecting melanin because the activation and excitation can be a continuous-wave (CW) mode near infrared (NIR) laser. Our previous work has demonstrated the melanin SMPAF images in sepia melanin, mouse hair, and mouse skin. In this study, we show the feasibility of using SMPAF to detect melanin in vivo. in vivo melanin SMPAF images of normal skin and benign nevus are demonstrated. SMPAF images add specificity for melanin detection than MPFM images and CRM images. Melanin SMPAF is a promising technology to enable early detection of melanoma for dermatologists.

  12. Thermal imaging method to visualize a hidden painting thermally excited by far infrared radiations

    NASA Astrophysics Data System (ADS)

    Davin, T.; Wang, X.; Chabane, A.; Pawelko, R.; Guida, G.; Serio, B.; Hervé, P.

    2015-06-01

    The diagnosis of hidden painting is a major issue for cultural heritage. In this paper, a non-destructive active infrared thermographic technique was considered to reveal paintings covered by a lime layer. An extended infrared spectral range radiation was used as the excitation source. The external long wave infrared energy source delivered to the surface is then propagated through the material until it encounters a painting zone. Due to several thermal effects, the sample surface then presents non-uniformity patterns. Using a high sensitive infrared camera, the presence of covered pigments can thus be highlighted by the analysis of the non-stationary phenomena. Reconstituted thermal contrast images of mural samples covered by a lime layer are shown.

  13. Pulse shaping multiphoton FRET microscopy

    NASA Astrophysics Data System (ADS)

    Brenner, Meredith H.; Cai, Dawen; Nichols, Sarah R.; Straight, Samuel W.; Hoppe, Adam D.; Swanson, Joel A.; Ogilvie, Jennifer P.

    2012-03-01

    Fluorescence Resonance Energy Transfer (FRET) microscopy is a commonly-used technique to study problems in biophysics that range from uncovering cellular signaling pathways to detecting conformational changes in single biomolecules. Unfortunately, excitation and emission spectral overlap between the fluorophores create challenges in quantitative FRET studies. It has been shown previously that quantitative FRET stoichiometry can be performed by selective excitation of donor and acceptor fluorophores. Extending this approach to two-photon FRET applications is difficult when conventional femtosecond laser sources are used due to their limited bandwidth and slow tuning response time. Extremely broadband titanium:sapphire lasers enable the simultaneous excitation of both donor and acceptor for two-photon FRET, but do so without selectivity. Here we present a novel two-photon FRET microscopy technique that employs pulse-shaping to perform selective excitation of fluorophores in live cells and detect FRET between them. Pulse-shaping via multiphoton intrapulse interference can tailor the excitation pulses to achieve selective excitation. This technique overcomes the limitation of conventional femtosecond lasers to allow rapid switching between selective excitation of the donor and acceptor fluorophores. We apply the method to live cells expressing the fluorescent proteins mCerulean and mCherry, demonstrating selective excitation of fluorophores via pulse-shaping and the detection of twophoton FRET. This work paves the way for two-photon FRET stoichiometry.

  14. Controlling electron transfer in condensed phase with bond-specific infrared excitation

    NASA Astrophysics Data System (ADS)

    Delor, Milan; Scattergood, Paul A.; Sazanovich, Igor V.; Keane, Theo; Greetham, Gregory M.; Meijer, Anthony J. H. M.; Towrie, Michael; Parker, Anthony W.; Weinstein, Julia A.

    2015-08-01

    Using an ultrafast electronic-vibrational pulse-sequence, we show that the outcome of light-induced ET can be radically altered by mode-specific infrared (IR) excitation of vibrations which are coupled to the ET-pathway. IR-control is particularly challenging in condensed phase systems due to the ultrafast timescales involved, in particular rapid intramolecular vibrational redistribution. We demonstrate how an IR-pulse following UV-excitation perturbs nuclear-electronic (vibronic) interactions within a donor-bridge-acceptor system similar in design to those utilized in (bio)chemical light-harvesting, and alters charge-transport pathways and product state yields.

  15. Multiphoton absorption in amyloid protein fibres

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

    2013-12-01

    Fibrillization of peptides leads to the formation of amyloid fibres, which, when in large aggregates, are responsible for diseases such as Alzheimer's and Parkinson's. Here, we show that amyloids have strong nonlinear optical absorption, which is not present in native non-fibrillized protein. Z-scan and pump-probe experiments indicate that insulin and lysozyme ?-amyloids, as well as ?-synuclein fibres, exhibit either two-photon, three-photon or higher multiphoton absorption processes, depending on the wavelength of light. We propose that the enhanced multiphoton absorption is due to a cooperative mechanism involving through-space dipolar coupling between excited states of aromatic amino acids densely packed in the fibrous structures. This finding will provide the opportunity to develop nonlinear optical techniques to detect and study amyloid structures and also suggests that new protein-based materials with sizable multiphoton absorption could be designed for specific applications in nanotechnology, photonics and optoelectronics.

  16. Gas phase collisional excitation of infrared emissions in the vicinity of the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Torr, Marsha R.; Torr, Douglas G.

    1988-01-01

    The implications of gas buildups around space vehicles are investigated in terms of induced photon emissions. Results indicate that significant effects arise from gas collisions between the relatively energetic ambient atoms and molecules and the atoms and molecules in the shuttle environment. It is suggested that such collision may transfer considerable energy to the gases in the shuttle environment, with the most likely emissions being vibrational and rotational radiation losses in the infrared due to direct collisional excitation.

  17. Mid-infrared ultrafast laser pulses induced third harmonic generation in nitrogen molecules on an excited state.

    PubMed

    Xie, Hongqiang; Li, Guihua; Yao, Jinping; Chu, Wei; Li, Ziting; Zeng, Bin; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We report on generation of third harmonic from nitrogen molecules on the excited state with a weak driver laser pulse at a mid-infrared wavelength. The excited nitrogen molecules are generated using a circularly polarized intense femtosecond pulse which produces energetic electrons by photoionization to realize collisional excitation of nitrogen molecules. Furthermore, since the third harmonic is generated using a pump-probe scheme, it enables investigation of the excited-state dynamics of nitrogen molecules produced under different conditions. We also perform a comparative investigation in excited argon atoms, revealing different decay dynamics of the molecules and atoms from the excited states in femtosecond laser induced filaments. PMID:26522886

  18. Mid-infrared ultrafast laser pulses induced third harmonic generation in nitrogen molecules on an excited state

    PubMed Central

    Xie, Hongqiang; Li, Guihua; Yao, Jinping; Chu, Wei; Li, Ziting; Zeng, Bin; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We report on generation of third harmonic from nitrogen molecules on the excited state with a weak driver laser pulse at a mid-infrared wavelength. The excited nitrogen molecules are generated using a circularly polarized intense femtosecond pulse which produces energetic electrons by photoionization to realize collisional excitation of nitrogen molecules. Furthermore, since the third harmonic is generated using a pump-probe scheme, it enables investigation of the excited-state dynamics of nitrogen molecules produced under different conditions. We also perform a comparative investigation in excited argon atoms, revealing different decay dynamics of the molecules and atoms from the excited states in femtosecond laser induced filaments. PMID:26522886

  19. Mid-infrared ultrafast laser pulses induced third harmonic generation in nitrogen molecules on an excited state

    NASA Astrophysics Data System (ADS)

    Xie, Hongqiang; Li, Guihua; Yao, Jinping; Chu, Wei; Li, Ziting; Zeng, Bin; Wang, Zhanshan; Cheng, Ya

    2015-11-01

    We report on generation of third harmonic from nitrogen molecules on the excited state with a weak driver laser pulse at a mid-infrared wavelength. The excited nitrogen molecules are generated using a circularly polarized intense femtosecond pulse which produces energetic electrons by photoionization to realize collisional excitation of nitrogen molecules. Furthermore, since the third harmonic is generated using a pump-probe scheme, it enables investigation of the excited-state dynamics of nitrogen molecules produced under different conditions. We also perform a comparative investigation in excited argon atoms, revealing different decay dynamics of the molecules and atoms from the excited states in femtosecond laser induced filaments.

  20. Multiphoton microscopy for blood vessel imaging: new non-invasive tools (Spectral, SHG, FLIM).

    PubMed

    Werkmeister, E; Kerdjoudj, H; Marchal, L; Stoltz, J F; Dumas, D

    2007-01-01

    Imaging thick and opaque tissue, like blood vessel, in a noninvasive mode with high resolution, is nowadays possible with multiphoton technology. A near-infrared excitation presents the advantage to be compatible with living specimens and allows a deep penetration into tissues. The nonlinear excitation process is followed by several deactivation ways, among which fluorescence emission can be represented with Spectral or Lifetime imaging. Applied to ex vivo blood vessel imaging, these techniques enabled us to discriminate cell structures (nucleus, cytoskeleton) by fluorescent labelling (Hoechst, QDots). Another method, based on 2-photon excitation and which doesn't need any exogenous dye has also been experimented on arteries: SHG (Second Harmonic Generation) is a diffusion process generated from organized structures. Collagen molecules give rise to a strong SHG signal, enabling us to image the arterial wall (3-dimensional extracellular matrix). PMID:17641398

  1. Clinical multiphoton and CARS microscopy

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; Weinigel, M.; Darvin, M. E.; Lademann, J.; König, K.

    2012-03-01

    We report on clinical CARS imaging of human skin in vivo with the certified hybrid multiphoton tomograph CARSDermaInspect. The CARS-DermaInspect provides simultaneous imaging of non-fluorescent intradermal lipid and water as well as imaging of two-photon excited fluorescence from intrinsic molecules. Two different excitation schemes for CARS imaging have been realized: In the first setup, a combination of fs oscillator and optical parametric oscillator provided fs-CARS pump and Stokes pulses, respectively. In the second setup a fs oscillator was combined with a photonic crystal fiber which provided a broadband spectrum. A spectral range out of the broadband-spectrum was selected and used for CARS excitation in combination with the residual fs-oscillator output. In both setups, in addition to CARS, single-beam excitation was used for imaging of two-photon excited fluorescence and second harmonic generation signals. Both CARS-excitation systems were successfully used for imaging of lipids inside the skin in vivo.

  2. Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab geometry

    E-print Network

    Vellekoop, Michel

    Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab excited by a radio frequency rf discharge in a slab geometry. A maximum continuous wave cw output power­7 Until now the research in this wave- length region was concentrated mainly on the improvement of solid

  3. Determining two-photon absorption cross sections via nonresonant multiphoton photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Kiser, John B.; Chandrasekharan, Nirmala; Cullum, Brian M.

    2007-09-01

    Multiphoton excitation of exogenous dyes and endogenous biochemical species has been used extensively for tissue diagnosis by fluorescence spectroscopy. Unfortunately, the majority of endogenous biochemical chromophores have low quantum yields, less than 0.2, therefore determining two-photon cross sections of weakly luminescencing molecules is difficult using two-photon fluorescence spectroscopy. Accurate determination of two-photon cross sections of these biochemicals could provide insight into fluorescence signal reduction caused by the absorption of excitation energy by non-target intracellular species. Non-resonant multiphoton photoacoustic spectroscopy (NMPPAS) is a novel technique we have developed for condensed matter measurements that has the potential for accurately determining two-photon absorption cross-sections of chemicals with small or non-existant fluorescence quantum yields. In this technique, near infrared light is used to generate an ultrasonic signal following a non-resonant two-photon excitation process. This ultrasonic wave is directly related to the non-radative relaxation of the chromophore of interest and is measured using a contact piezoelectric ultrasonic transducer. The signal from the ultrasonic transducer can then be used to calculate two-photon absorption cross sections. This paper will describe the validation of this technique by measuring the two-photon absorption cross- sections of well characterized chromophores such as rhodamine B and coumarin 1 in solution as well as riboflavin in a gelatin tissue phantom.

  4. Surface plasmon excitation at near-infrared wavelengths in polymer optical fibers.

    PubMed

    Hu, Xuehao; Mégret, Patrice; Caucheteur, Christophe

    2015-09-01

    We report the first excitation of surface plasmon waves at near-infrared telecommunication wavelengths using polymer optical fibers (POFs) made of poly(methyl methacrylate) (PMMA). For this, weakly tilted fiber-Bragg gratings (TFBGs) have been photo-inscribed in the core of step-index POFs and the fiber coated with a thin gold layer. Surface plasmon resonance is excited with radially polarized modes and is spectrally observed as a singular extinction of some cladding-mode resonances in the transmitted amplitude spectrum of gold-coated TFBGs. The refractometric sensitivity can reach ?550??nm/RIU (refractive index unit) with a figure of merit of more than 2000 and intrinsic temperature self-compensation. This kind of sensor is particularly relevant to in situ operation. PMID:26368696

  5. Laser action in chromium-activated forsterite for near-infrared excitation

    SciTech Connect

    Petricevic, V.; Gayen, S.K.; Alfano, R.R.

    1988-10-15

    Recently, the authors reported room-temperature pulsed-laser action in chromium-activated forsterite (Cr:Mg/sub 2/SiO/sub 4/). The free-running laser output was centered at 1235 nm with a spectral bandwidth (full width at half-maximum,FWHM) of 22 nm. The laser emission was stimulated by the 532-nm excitation of the green-red absorption band of the system. The crystal is characterized by a shallow absorption band spanning the 850-1200-nm wavelength range, which overlaps a significant portion of the emission spectrum and was previously thought to inhibit laser action in that region. In this communication, laser action in chromium-doped forsterite for 1064-nm excitation of this band is reported. The near infrared absorption thus turns out to be effective in populating the initial level of the lasing transition.

  6. Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C60 vs Xe

    NASA Astrophysics Data System (ADS)

    Shchatsinin, I.; Ritze, H.-H.; Schulz, C. P.; Hertel, I. V.

    2009-05-01

    Ionization and fragmentation of C60 fullerenes are studied by time-of-flight mass spectrometry, in elliptically polarized femtosecond laser fields at 797 nm of intensities I0=(0.5-4.3)×1014Wcm-2 . Xe atoms serve as a test case. We derive a qualitative theory describing such polarization studies. It turns out that polarization dependence can very sensitively distinguish single active electron (SAE) and multiple active electrons dynamics. In the case of Xe a clear signature of SAE dynamics is observed, with very pronounced changes in the ion yield as a function of ellipticity, indicative of N=5-8 and 18-22 photon processes for Xe+ and Xe2+ , respectively. In contrast, only a moderate polarization dependence is observed in the C60 case, although at least 5 h? photons at 797 nm are needed to generate C60+ and additional 11 for C602+ . At lower intensities, a moderate reduction in the ion yield for circular polarization establishes a two-photon SAE absorption process, connected with the key role of the lowest unoccupied molecular orbital (LUMO)+1(t1g) as “doorway state.” The absence of any polarization effect at 399 nm corroborates this finding. At high intensities enhanced fragmentation is observed, which is tentatively attributed to returning loops of electron trajectories by the combined action of the C60+ field and the circularly polarized laser field—in contrast to conventional wisdom that linear polarization should lead to an enhanced recolliding electron yield. No sign of a pronounced multiphoton polarization signature with five and more photons is seen for C60 which would be predicted by the SAE picture—although the slopes of the ion yield as a function of intensity are given by the corresponding power laws ?I0N . This is taken as clear evidence of multielectron dynamics after reaching the doorway state.

  7. Excited-state dynamics of protochlorophyllide revealed by subpicosecond infrared spectroscopy.

    PubMed

    Colindres-Rojas, Miriam; Wolf, Matthias M N; Gross, Ruth; Seidel, Sonja; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen; Hermann, Gudrun; Diller, Rolf

    2011-01-01

    To gain a better understanding of the light-induced reduction of protochlorophyllide (PChlide) to chlorophyllide as a key regulatory step in chlorophyll synthesis, we performed transient infrared absorption measurements on PChlide in d4-methanol. Excitation in the Q-band at 630 nm initiates dynamics characterized by three time constants: ?? = 3.6 ± 0.2, ?? = 38 ± 2, and ?? = 215 ± 8 ps. As indicated by the C13'=O carbonyl stretching mode in the electronic ground state at 1686 cm?¹, showing partial ground-state recovery, and in the excited electronic state at 1625 cm?¹, showing excited-state decay, ?? describes the formation of a state with a strong change in electronic structure, and ?? represents the partial recovery of the PChlide electronic ground state. Furthermore, ?? corresponds with vibrational energy relaxation. The observed kinetics strongly suggest a branched reaction scheme with a branching ratio of 0.5 for the path leading to the PChlide ground state on the 200 ps timescale and the path leading to a long-lived state (>700 ps). The results clearly support a branched reaction scheme, as proposed previously, featuring the formation of an intramolecular charge transfer state with ?25 ps, its decay into the PChlide ground state with 200 ps, and a parallel reaction path to the long-lived PChlide triplet state. PMID:21190679

  8. Excited-State Dynamics of Protochlorophyllide Revealed by Subpicosecond Infrared Spectroscopy

    PubMed Central

    Colindres-Rojas, Miriam; Wolf, Matthias M.N.; Groß, Ruth; Seidel, Sonja; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen; Hermann, Gudrun; Diller, Rolf

    2011-01-01

    To gain a better understanding of the light-induced reduction of protochlorophyllide (PChlide) to chlorophyllide as a key regulatory step in chlorophyll synthesis, we performed transient infrared absorption measurements on PChlide in d4-methanol. Excitation in the Q-band at 630 nm initiates dynamics characterized by three time constants: ?1 = 3.6 ± 0.2, ?2 = 38 ± 2, and ?3 = 215 ± 8 ps. As indicated by the C13?=O carbonyl stretching mode in the electronic ground state at 1686 cm?1, showing partial ground-state recovery, and in the excited electronic state at 1625 cm?1, showing excited-state decay, ?2 describes the formation of a state with a strong change in electronic structure, and ?3 represents the partial recovery of the PChlide electronic ground state. Furthermore, ?1 corresponds with vibrational energy relaxation. The observed kinetics strongly suggest a branched reaction scheme with a branching ratio of 0.5 for the path leading to the PChlide ground state on the 200 ps timescale and the path leading to a long-lived state (>>700 ps). The results clearly support a branched reaction scheme, as proposed previously, featuring the formation of an intramolecular charge transfer state with ?25 ps, its decay into the PChlide ground state with 200 ps, and a parallel reaction path to the long-lived PChlide triplet state. PMID:21190679

  9. High contrast in vivo bioimaging using multiphoton upconversion in novel rare-earth-doped fluoride upconversion nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Guanying; Yang, Chunhui; Prasad, Paras N.

    2013-02-01

    Upconversion in rare-earth ions is a sequential multiphoton process that efficiently converts two or more low-energy photons, which are generally near infrared (NIR) light, to produce anti-Stokes emission of a higher energy photon (e.g., NIR, visible, ultraviolet) using continuous-wave (cw) diode laser excitation. Here, we show the engineering of novel, efficient, and biocompatible NIRin-to-NIRout upconversion nanoparticles for biomedical imaging with both excitation and emission being within the "optical transparency window" of tissues. The small animal whole-body imaging with exceptional contrast (signal-to-noise ratio of 310) was shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles. An imaging depth as deep as 3.2-cm was successfully demonstrated using thick animal tissue (pork) under cw laser excitation at 980 nm.

  10. In vivo multiphoton tomography of skin cancer

    NASA Astrophysics Data System (ADS)

    König, Karsten; Riemann, Iris; Ehlers, Alexander; Buckle, Rainer; Dimitrow, Enrico; Kaatz, Martin; Fluhr, Joachim; Elsner, Peter

    2006-02-01

    The multiphoton tomograph DermaInspect was used to perform first clinical studies on the early non-invasive detection of skin cancer based on non-invasive optical sectioning of skin by two-photon autofluorescence and second harmonic generation. In particular, deep-tissue pigmented lesions -nevi- have been imaged with intracellular resolution using near infrared (NIR) femtosecond laser radiation. So far, more than 250 patients have been investigated. Cancerous tissues showed significant morphological differences compared to normal skin layers. In the case of malignant melanoma, the occurrence of luminescent melanocytes has been detected. Multiphoton tomography will become a novel non-invasive method to obtain high-resolution 3D optical biopsies for early cancer detection, treatment control, and in situ drug screening.

  11. Multiphoton tomography to detect chemo- and biohazards

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2015-03-01

    In vivo high-resolution multiphoton/CARS tomography provides optical biopsies with 300 nm lateral resolution with chemical fingerprints. Thousands of volunteers and patients have been investigated for early cancer diagnosis, evaluation of anti-ageing cosmetic products, and changes of cellular metabolism by UV exposure and decreased oxygen supply. The skin as the outermost and largest organ is also the major target of CB agents. Current UV-based sensors are useful for bio-aerosol sensing but not for evaluating exposed in vivo skin. Here we evaluate the use of 4D multiphoton/CARS tomographs based on near infrared femtosecond laser radiation, time-correlated single photon counting (FLIM) and white light generation by photonic crystal fibers to detect bio- and chemohazards in human in vivo skin using twophoton fluorescence, SHG, and Raman signals.

  12. Carrier Lifetime Measurements in Long-Wave Infrared InAs/GaSb Superlattices Under Low Excitation Conditions

    NASA Astrophysics Data System (ADS)

    Wang, Ding; Donetsky, Dmitri; Jung, Seungyong; Belenky, Gregory

    2012-11-01

    Minority carrier lifetime in long-wave infrared (LWIR) type II InAs/GaSb superlattices was studied using the optical modulation response (OMR) technique in wide ranges of excitation and temperature. The measured carrier lifetime was found to increase superexponentially with decreasing excitation power density below the level of 1 mW/cm2 to 2 mW/cm2. The phenomenon was qualitatively explained by the presence of shallow trapping centers.

  13. Identification of glucosinolates in capers by LC-ESI-hybrid linear ion trap with Fourier transform ion cyclotron resonance mass spectrometry (LC-ESI-LTQ-FTICR MS) and infrared multiphoton dissociation.

    PubMed

    Bianco, Giuliana; Lelario, Filomena; Battista, Fabio Giuseppe; Bufo, Sabino A; Cataldi, Tommaso R I

    2012-09-01

    An liquid chromatography-mass spectrometry method using electrospray ionization in negative ion mode coupled with a hybrid quadrupole linear ion trap and Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was applied to characterize of intact glucosinolates (GLSs) in crude sample extracts of wild bud flowers of Capparis spinosa (Capparis species, family Capparaceae). Structural information of GLSs was obtained upon precursor ions' isolation within the FTICR trapping cell and subsequent fragmentation induced by infrared multiphoton dissociation (IRMPD). Such a fragmentation was found very useful in terms of chemical identification of all precursor ions [M-H](-) including sulfur-rich GLSs reported here for the first time. Along with most common GLSs already found in capers such as glucocapparin, isopropyl/n-propyl-GLS, mercapto-glucocapparin, and two indolic GLS, i.e., 4-hydroxyglucobrassicin and glucobrassicin, the occurrence of the uncommon glycinyl-glucocapparin as well as two sulfur-rich GLSs is reported. IRMPD showed an increased selectivity towards disulfide bond cleavages with thiol migration, suggesting the side chain structure of non-targeted compounds, i.e., disulfanyl-glucocapparin and trisulfanyl-glucocapparin. Glucocapparin [2.05?±?0.25?mg/g, dry weight (dw)] was the most abundant GLS, followed by glucobrassicin (232?±?18?µg/g, dw) and 4-hydroxyglucobrassicin (89?±?12?µg/g, dw). All other compounds were present at very low content ranging from 0.5 to 1.5?µg/g dw. PMID:22972784

  14. Compact fixed wavelength femtosecond oscillators for multi-photon imaging

    NASA Astrophysics Data System (ADS)

    Hakulinen, T.; Klein, J.; Zadoyan, R.; Baldacchini, T.; Franke, T.

    2015-03-01

    In recent years two-photon microscopy with fixed-wavelength has raised increasing interest in life-sciences: Two-photon (2P) absorption spectra of common dyes are broader than single-photon ones. Therefore, excitation of several dyes simultaneously with a single IR laser wavelength is feasible and could be seen as an advantage in 2P microscopy. We used pulsed fixed-wavelength infrared lasers with center wavelength at 1040 nm, for two-photon microscopy in a variety of biologically relevant samples, among these a mouse brain sample, a mouse artery (within the animal, acute preparation), and a preparation of mouse bladder. The 1040 nm laser proved to be efficient not only in exciting fluorescence from yellow fluorescent protein (YFP) and red fluorescent dyes, but also for second harmonic generation (SHG) signals from muscle tissue and collagen. With this work we demonstrate that economical, small-footprint fixedwavelength lasers can present an interesting alternative to tunable lasers that are commonly used in multiphoton microscopy.

  15. Multiphoton tomography of intratissue tattoo nanoparticles

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2012-02-01

    Most of today's intratissue tattoo pigments are unknown nanoparticles. So far, there was no real control of their use due to the absence of regulations. Some of the tattoo pigments contain carcinogenic amines e.g. azo pigment Red 22. Nowadays, the European Union starts to control the administration of tattoo pigments. There is an interest to obtain information on the intratissue distribution, their interaction with living cells and the extracellular matrix, and the mechanisms behind laser tattoo removal. Multiphoton tomographs are novel biosafety and imaging tools that can provide such information non-invasively and without further labeling. When using the spectral FLIM module, spatially-resolved emission spectra, excitation spectra, and fluorescence lifetimes can pr provided. Multiphoton tomographs are used by all major cosmetic comapanies to test the biosafety of sunscreen nanoparticles.

  16. Characterizing lamina propria of human gastric mucosa by multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Y. C.; Yang, H. Q.; Chen, G.; Zhuo, S. M.; Chen, J. X.; Yan, J.

    2011-01-01

    Lamina propria (LP) of gastric mucosa plays an important role in progression of gastric cancer because of the site at where inflammatory reactions occur. Multiphoton imaging has been recently employed for microscopic examination of intact tissue. In this paper, using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), high resolution multiphoton microscopic images of lamina propria (LP) are obtained in normal human gastric mucosa at excitation wavelength ?ex = 800 nm. The main source of tissue TPEF originated from the cells of gastric glands, and loose connective tissue, collagen, produced SHG signals. Our results demonstrated that MPM can be effective for characterizing the microstructure of LP in human gastric mucosa. The findings will be helpful for diagnosing and staging early gastric cancer in the clinics.

  17. Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube

    E-print Network

    Cha, Jae Won

    Multifocal multiphoton microscopy (MMM) improves imaging speed over a point scanning approach by parallelizing the excitation process. Early versions of MMM relied on imaging detectors to record emission signals from ...

  18. Cutaneous melanin exhibiting fluorescence emission under near-infrared light excitation.

    PubMed

    Huang, Zhiwei; Zeng, Haishan; Hamzavi, Iltefat; Alajlan, Abdulmajeed; Tan, Eileen; McLean, David I; Lui, Harvey

    2006-01-01

    Under ultraviolet and visible light excitation, melanin is essentially a nonfluorescent substance. This work reports our study on near-infrared (NIR) fluorescence properties of melanins, and explores potential applications of NIR fluorescence techniques for evaluating skin disorders involving melanin. The NIR fluorescence spectrum is obtained using a fiber optic NIR spectrometer under 785-nm laser excitation. In vitro measurements are performed on synthetic dihydroxyphenylalanine (DOPA) melanin, melanin extracted from Sepia ink sacs, human hair, animal fur, and bird feathers. Paired spectral comparisons of white and black skin appendages show that melanization of hair, fur, or feathers more than doubles the NIR fluorescence. In vivo NIR autofluorescence of normal dorsal and volar forearm skin of 52 volunteers is measured. Dorsal forearm skin, which is darker than volar skin, exhibits significantly greater NIR fluorescence. Patients with vitiligo (n=4), compound nevus (n=3), nevus of Ota (n=1), superficial spreading melanoma (n=3), and postinflammatory hyperpigmentation (n=1) are also evaluated. NIR fluorescence is greater within the lesion than the surrounding normal skin for all these conditions except vitiligo, where the converse was true. The observed melanin NIR fluorescence provides a new approach to in vitro and in vivo melanin detection and quantification that may be particularly useful for evaluating pigmented skin lesions. PMID:16822060

  19. Highly Emitting Near-Infrared Lanthanide “Encapsulated Sandwich” Metallacrown Complexes with Excitation Shifted Toward Lower Energy

    PubMed Central

    2015-01-01

    Near-infrared (NIR) luminescent lanthanide complexes hold great promise for practical applications, as their optical properties have several complementary advantages over organic fluorophores and semiconductor nanoparticles. The fundamental challenge for lanthanide luminescence is their sensitization through suitable chromophores. The use of the metallacrown (MC) motif is an innovative strategy to arrange several organic sensitizers at a well-controlled distance from a lanthanide cation. Herein we report a series of lanthanide “encapsulated sandwich” MC complexes of the form Ln3+[12-MCZn(II),quinHA-4]2[24-MCZn(II),quinHA-8] (Ln3+[Zn(II)MCquinHA]) in which the MC framework is formed by the self-assembly of Zn2+ ions and tetradentate chromophoric ligands based on quinaldichydroxamic acid (quinHA). A first-generation of luminescent MCs was presented previously but was limited due to excitation wavelengths in the UV. We report here that through the design of the chromophore of the MC assembly, we have significantly shifted the absorption wavelength toward lower energy (450 nm). In addition to this near-visible inter- and/or intraligand charge transfer absorption, Ln3+[Zn(II)MCquinHA] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLnL = 2.88(2)%, ?obs = 150.7(2) ?s; Nd3+, QLnL = 1.35(1)%, ?obs = 4.11(3) ?s; Er3+, QLnL = 3.60(6)·10–2%, ?obs = 11.40(3) ?s), and excellent photostability. Quantum yields of Nd3+ and Er3+ MCs in the solid state and in deuterated solvents, upon excitation at low energy, are the highest values among NIR-emitting lanthanide complexes containing C–H bonds. The versatility of the MC strategy allows modifications in the excitation wavelength and absorptivity through the appropriate design of the ligand sensitizer, providing a highly efficient platform with tunable properties. PMID:24432702

  20. Highly emitting near-infrared lanthanide "encapsulated sandwich" metallacrown complexes with excitation shifted toward lower energy.

    PubMed

    Trivedi, Evan R; Eliseeva, Svetlana V; Jankolovits, Joseph; Olmstead, Marilyn M; Petoud, Stéphane; Pecoraro, Vincent L

    2014-01-29

    Near-infrared (NIR) luminescent lanthanide complexes hold great promise for practical applications, as their optical properties have several complementary advantages over organic fluorophores and semiconductor nanoparticles. The fundamental challenge for lanthanide luminescence is their sensitization through suitable chromophores. The use of the metallacrown (MC) motif is an innovative strategy to arrange several organic sensitizers at a well-controlled distance from a lanthanide cation. Herein we report a series of lanthanide “encapsulated sandwich” MC complexes of the form Ln3+ [12-MC(Zn(II),quinHA)-4]2[24-MC(Zn(II),quinHA)-8] (Ln3+ [Zn(II)MC(quinHA)]) in which the MC framework is formed by the self-assembly of Zn2+ ions and tetradentate chromophoric ligands based on quinaldichydroxamic acid (quinHA). A first-generation of luminescent MCs was presented previously but was limited due to excitation wavelengths in the UV. We report here that through the design of the chromophore of the MC assembly, we have significantly shifted the absorption wavelength toward lower energy (450 nm). In addition to this near-visible inter- and/or intraligand charge transfer absorption, Ln3+ [Zn(II)MC(quinHA)] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLn(L) = 2.88(2)%, ?obs = 150.7(2) ?s; Nd3+, QLn(L) = 1.35(1)%, ?obs = 4.11(3) ?s; Er3+, QLn(L) = 3.60(6)·10–2%, ?obs = 11.40(3) ?s), and excellent photostability. Quantum yields of Nd3+ and Er3+ MCs in the solid state and in deuterated solvents, upon excitation at low energy, are the highest values among NIR-emitting lanthanide complexes containing C–H bonds. The versatility of the MC strategy allows modifications in the excitation wavelength and absorptivity through the appropriate design of the ligand sensitizer, providing a highly efficient platform with tunable properties. PMID:24432702

  1. Femtosecond transient infrared and stimulated Raman spectroscopy shed light on the relaxation mechanisms of photo-excited peridinin

    NASA Astrophysics Data System (ADS)

    Di Donato, Mariangela; Ragnoni, Elena; Lapini, Andrea; Foggi, Paolo; Hiller, Roger G.; Righini, Roberto

    2015-06-01

    By means of one- and two-dimensional transient infrared spectroscopy and femtosecond stimulated Raman spectroscopy, we investigated the excited state dynamics of peridinin, a carbonyl carotenoid occurring in natural light harvesting complexes. The presence of singly and doubly excited states, as well as of an intramolecular charge transfer (ICT) state, makes the behavior of carbonyl carotenoids in the excited state very complex. In this work, we investigated by time resolved spectroscopy the relaxation of photo-excited peridinin in solvents of different polarities and as a function of the excitation wavelength. Our experimental results show that a characteristic pattern of one- and two-dimensional infrared bands in the C=C stretching region allows monitoring the relaxation pathway. In polar solvents, moderate distortions of the molecular geometry cause a variation of the single/double carbon bond character, so that the partially ionic ICT state is largely stabilized by the solvent reorganization. After vertical photoexcitation at 400 nm of the S2 state, the off-equilibrium population moves to the S1 state with ca. 175 fs time constant; from there, in less than 5 ps, the non-Franck Condon ICT state is reached, and finally, the ground state is recovered in 70 ps. That the relevant excited state dynamics takes place far from the Franck Condon region is demonstrated by its noticeable dependence on the excitation wavelength.

  2. Multiphoton Biomedical Imaging and Photodynamic Therapy: Agents & Applications

    E-print Network

    Van Stryland, Eric

    -reactive model Hydrophobic and hydrophilic dyes Two-Photon Photodynamic Therapy #12;"Two-photon laser scanning at the focus of the scanning pulsed-infrared laser beam, resulting in a much less harmful light dose duringMultiphoton Biomedical Imaging and Photodynamic Therapy: Agents & Applications Kevin D. Belfield

  3. Non Destructive Testing by active infrared thermography coupled with shearography under same optical heat excitation

    NASA Astrophysics Data System (ADS)

    Theroux, Louis-Daniel; Dumoulin, Jean; Maldague, Xavier

    2014-05-01

    As infrastructures are aging, the evaluation of their health is becoming crucial. To do so, numerous Non Destructive Testing (NDT) methods are available. Among them, thermal shearography and active infrared thermography represent two full field and contactless methods for surface inspection. The synchronized use of both methods presents multiples advantages. Most importantly, both NDT are based on different material properties. Thermography depend on the thermal properties and shearography on the mechanical properties. The cross-correlation of both methods result in a more accurate and exact detection of the defects. For real site application, the simultaneous use of both methods is simplified due to the fact that the excitation method (thermal) is the same. Active infrared thermography is the measure of the temperature by an infrared camera of a surface subjected to heat flux. Observation of the variation of temperature in function of time reveal the presence of defects. On the other hand, shearography is a measure of out-of-plane surface displacement. This displacement is caused by the application of a strain on the surface which (in our case) take the form of a temperature gradient inducing a thermal stress To measure the resulting out-of-plane displacement, shearography exploit the relation between the phase difference and the optical path length. The phase difference is measured by the observation of the interference between two coherent light beam projected on the surface. This interference is due to change in optical path length as the surface is deformed [1]. A series of experimentation have been conducted in laboratory with various sample of concrete reinforced with CFRP materials. Results obtained reveal that with both methods it was possible to detect defects in the gluing. An infrared lamp radiating was used as the active heat source. This is necessary if measurements with shearography are to be made during the heating process. A heating lamp in the visible spectrum would hinder the projected light beam since a laser with wavelength of 532 nm was used as the coherent light source. Experimentations were successful, but only with mitigated efficiency for shearography [2]. The thermal response was the fastest and it was possible to fully locate all defects. For shearography, the available equipment forced us to restrict the area of observation to only one defect at a time (roughly 100 cm²). Numerical models were designed based on the multiple sample tested in the experimental step of the study. Using the COMSOL© finite elements modeling software, numerous simulations yielded results in accordance with experimental data. Different types of defect could be modeled and showed that both shearography and thermography have different sensibility in function of the nature of the defect. Furthermore, analysis of the simulated results demonstrated a relation between the contrast evolution of the temperature and displacement field. In the near future, we expect to make several improvement to our experimental setup. As for the numerical model, some small disparities between the theoretical and experimental results still remain to be addressed. The numerical model could be improved but to do so it requires to raise the shearographic measurements sampling rate close to the one used for infrared thermography. Once this issue will be resolved, it will be possible to use experimental data to refine the numerical model. So, accurate models will be helpful to optimize the overall efficiency of the coupling of thermal shearography and active infrared thermography for in situ NDT application. References [1] Y.Y. Hung, C.Y. Liand, Image-shearing camera for direct measurement of surface strains, Applied Optics, Vol. 18, n°7, pages 1046-1051, 1979 [2] L-D. Théroux, J. Dumoulin, X. Maldague, Square heating applied to shearography and active infrared thermography measurements coupling: form feasibility test in laboratory to numerical study of pultruded CFRP plates glued on concrete specimen, STRAIN journal, in press

  4. Multispot multiphoton Ca²? imaging in acute myocardial slices.

    PubMed

    Borile, Giulia; de Mauro, Claudio; Urbani, Andrea; Alfieri, Domenico; Pavone, Francesco S; Mongillo, Marco

    2015-05-01

    Multiphoton microscopy has become essential for dynamic imaging in thick living tissues. High-rate, full-field image acquisition in multiphoton microscopy is achievable by parallelization of the excitation and detection pathways. We developed our approach via a diffractive optical element which splits a pulsed laser into 16 beamlets and exploits a descanned detection system consisting of an array of beamlet-associated photomultiplier tubes. The optical performance of the multiphoton multispot system (MCube) has been characterized in cardiac tissue sections and subsequently used for the first time for fluorescence imaging of cardiomyocyte Ca²? dynamics in viable acute cardiac slices. Multispot multiphoton microscopy (MMM) has never been used before to monitor Ca²? dynamics in thick, viable tissue samples. Acute heart slices are a powerful close-to-in vivo model of Ca²? imaging allowing the simultaneous observation of several cells in their own tissue environment, exploiting the multiphoton excitation ability to penetrate scattering tissues. Moreover, we show that the concurrent high spatial and temporal resolutions afforded by the parallel scanning in MMM can be exploited to simultaneously assess subcellular Ca²? dynamics in different cells in the tissue. We recorded local Ca²? release events including macrosparks, travelling waves, and rotors. PMID:25517401

  5. Multispot multiphoton Ca2+ imaging in acute myocardial slices

    NASA Astrophysics Data System (ADS)

    Borile, Giulia; de Mauro, Claudio; Urbani, Andrea; Alfieri, Domenico; Pavone, Francesco S.; Mongillo, Marco

    2015-05-01

    Multiphoton microscopy has become essential for dynamic imaging in thick living tissues. High-rate, full-field image acquisition in multiphoton microscopy is achievable by parallelization of the excitation and detection pathways. We developed our approach via a diffractive optical element which splits a pulsed laser into 16 beamlets and exploits a descanned detection system consisting of an array of beamlet-associated photomultiplier tubes. The optical performance of the multiphoton multispot system (MCube) has been characterized in cardiac tissue sections and subsequently used for the first time for fluorescence imaging of cardiomyocyte Ca2+ dynamics in viable acute cardiac slices. Multispot multiphoton microscopy (MMM) has never been used before to monitor Ca2+ dynamics in thick, viable tissue samples. Acute heart slices are a powerful close-to-in vivo model of Ca2+ imaging allowing the simultaneous observation of several cells in their own tissue environment, exploiting the multiphoton excitation ability to penetrate scattering tissues. Moreover, we show that the concurrent high spatial and temporal resolutions afforded by the parallel scanning in MMM can be exploited to simultaneously assess subcellular Ca2+ dynamics in different cells in the tissue. We recorded local Ca2+ release events including macrosparks, travelling waves, and rotors.

  6. Free electron laser-Fourier transform ion cyclotron resonance mass spectrometry facility for obtaining infrared multiphoton dissociation spectra of gaseous ions

    SciTech Connect

    Valle, Jose J.; Eyler, John R.; Oomens, Jos; Moore, David T.; Meer, A.F.G. van der; Helden, Gert von; Meijer, Gerard; Hendrickson, Christopher L.; Marshall, Alan G.; Blakney, Gregory T.

    2005-02-01

    A Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer has been installed at a free electron laser (FEL) facility to obtain infrared absorption spectra of gas phase ions by infrared multiple photon dissociation (IRMPD). The FEL provides continuously tunable infrared radiation over a broad range of the infrared spectrum, and the FT-ICR mass spectrometer, utilizing a 4.7 Tesla superconducting magnet, permits facile formation, isolation, trapping, and high-mass resolution detection of a wide range of ion classes. A description of the instrumentation and experimental parameters for these experiments is presented along with preliminary IRMPD spectra of the singly-charged chromium-bound dimer of diethyl ether (Cr(C{sub 4}H{sub 10}O){sub 2}{sup +}) and the fluorene molecular ion (C{sub 13}H{sub 10}{sup +}). Also presented is a brief comparison of the fluorene cation spectrum obtained by the FT-ICR-FEL with an earlier spectrum recorded using a quadrupole ion trap (QIT)

  7. Performances of high numerical aperture water and oil immersion objective in deep-tissue, multi-photon microscopic imaging of excised human skin.

    PubMed

    Dong, Chen-Yuan; Yu, Betty; Kaplan, Peter D; So, Peter T C

    2004-01-01

    Multi-photon fluorescence microscopy (MPFM) is a powerful technique for imaging scattering, biological specimens in depth. In addition to the sectioning effect generated by the point-like excitation volume, the near-infrared wavelengths used for multi-photon excitation allow deeper penetration into optically turbid specimens. In physiological specimens, the optical properties such as the scattering coefficients and refractive indices are often heterogeneous. In these specimens, it is not clear which type of immersion objective can provide optimized images in-depth. In particular, in-depth dermatological imaging applications using MPFM requires such optimization to obtain qualitative and quantitative information from the skin specimens. In this work, we address this issue by comparing the performances of two common types of high numerical aperture (NA) objectives: water-immersion and oil-immersion. A high-quality water-immersion objective (Zeiss, 40 x C-Apochromat, NA 1.2) and a comparable oil-immersion objective (Zeiss, 40 x Fluar, NA 1.25) were used for in-depth imaging of autofuorescent excised human skin and sulforhodamine B treated human skin specimens. Our results show that in the epidermal layers, the two types of immersion objectives perform comparably. However, in the dermis, multi-photon imaging using the oil immersion objective results in stronger fluorescence detection. These observations are most likely due to the degraded point-spread-function (PSF) caused by refractive index mismatch between the epidermis and the dermis. PMID:14677137

  8. A novel flexible clinical multiphoton tomograph for early melanoma detection, skin analysis, testing of anti-age products, and in situ nanoparticle tracking

    NASA Astrophysics Data System (ADS)

    Weinigel, Martin; Breunig, Hans Georg; Gregory, Axel; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer; König, Karsten

    2010-02-01

    High-resolution 3D microscopy based on multiphoton induced autofluorescence and second harmonic generation have been introduced in 1990. 13 years later, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have first been launched by JenLab company with the tomography DermaInspect®. This year, the second generation of clinical multiphoton tomographs was introduced. The novel multiphoton tomograph MPTflex, equipped with a flexible articulated optical arm, provides an increased flexibility and accessibility especially for clinical and cosmetical examinations. Improved image quality and signal to noise ratio (SNR) are achieved by a very short source-drain spacing, by larger active areas of the detectors and by single photon counting (SPC) technology. Shorter image acquisition time due to improved image quality reduces artifacts and simplifies the operation of the system. The compact folded optical design and the light-weight structure of the optical head eases the handling. Dual channel detectors enable to distinguish between intratissue elastic fibers and collagenous structures simultaneously. Through the use of piezo-driven optics a stack of optical cross-sections (optical sectioning) can be acquired and 3D imaging can be performed. The multiphoton excitation of biomolecules like NAD(P)H, flavins, porphyrins, elastin, and melanin is done by picojoule femtosecond laser pulses from an tunable turn-key femtosescond near infrared laser system. The ability for rapid high-quality image acquisition, the user-friendly operation of the system and the compact and flexible design qualifies this system to be used for melanoma detection, diagnostics of dermatological disorders, cosmetic research and skin aging measurements as well as in situ drug monitoring and animal research.

  9. Fibre-coupled multiphoton microscope with adaptive motion compensation

    PubMed Central

    Sherlock, Ben; Warren, Sean; Stone, James; Neil, Mark; Paterson, Carl; Knight, Jonathan; French, Paul; Dunsby, Chris

    2015-01-01

    To address the challenge of sample motion during in vivo imaging, we present a fibre-coupled multiphoton microscope with active axial motion compensation. The position of the sample surface is measured using optical coherence tomography and fed back to a piezo actuator that adjusts the axial location of the objective to compensate for sample motion. We characterise the system’s performance and demonstrate that it can compensate for axial sample velocities up to 700 µm/s. Finally we illustrate the impact of motion compensation when imaging multiphoton excited autofluorescence in ex vivo mouse skin. PMID:26137387

  10. Fibre-coupled multiphoton microscope with adaptive motion compensation.

    PubMed

    Sherlock, Ben; Warren, Sean; Stone, James; Neil, Mark; Paterson, Carl; Knight, Jonathan; French, Paul; Dunsby, Chris

    2015-05-01

    To address the challenge of sample motion during in vivo imaging, we present a fibre-coupled multiphoton microscope with active axial motion compensation. The position of the sample surface is measured using optical coherence tomography and fed back to a piezo actuator that adjusts the axial location of the objective to compensate for sample motion. We characterise the system's performance and demonstrate that it can compensate for axial sample velocities up to 700 µm/s. Finally we illustrate the impact of motion compensation when imaging multiphoton excited autofluorescence in ex vivo mouse skin. PMID:26137387

  11. Multi-photon quantum communication in quantum networks

    E-print Network

    Wei Qin; Chuan Wang; Ye Cao; Gui Lu Long

    2015-03-17

    We propose and analyze a multiphoton-state coherent transport protocol in a coupled-resonator quantum network. A multiphoton swap gate between two antipodes can be achieved with neither external modulation nor coupling strength engineering. Moreover, we extend this result to a coupled-resonator chain of arbitrary length with different coupling strengths. Effects of decoherence via quantum nondemolition interaction are studied with sources including vacuum quantum fluctuation and bath thermal excitations when the bath is in the thermal equilibrium state. These observations are helpful to understand the decoherence effects on quantum communication in quantum coupled-resonator systems.

  12. Infrared Multiphoton Dissociation Spectroscopy of a Gas-Phase Complex of Uranyl and 3-Oxa-Glutaramide: An Extreme Red-Shift of the [O=U=O]²? Asymmetric Stretch

    SciTech Connect

    Gibson, John K.; Hu, Hanshi; Van Stipdonk, Michael J.; Berden, Giel; Oomens, Jos; Li, Jun

    2015-04-09

    The gas-phase complex UO?(TMOGA)?²? (TMOGA = tetramethyl-3-oxa-glutaramide) prepared by electrospray ionization was characterized by infrared multiphoton dissociation (IRMPD) spectroscopy. The IRMPD spectrum from 700–1800 cm?¹ was interpreted using a computational study based on density functional theory. The predicted vibrational frequencies are in good agreement with the measured values, with an average deviation of only 8 cm?¹ (<1%) and a maximum deviation of 21 cm?¹ (<2%). The only IR peak assigned to the linear uranyl moiety was the asymmetric ?? mode, which appeared at 965 cm?¹ and was predicted by DFT as 953 cm?¹. This ?? frequency is red-shifted relative to bare uranyl, UO?²?, by ca. 150 cm?¹ due to electron donation from the TMOGA ligands. Based on the degree of red-shifting, it is inferred that two TMOGA oxygen-donor ligands have a greater effective gas basicity than the four monodentate acetone ligands in UO?(acetone)?²?. The uranyl ?? frequency was also computed for uranyl coordinated by two TMGA ligands, in which the central Oether of TMOGA has been replaced by CH?. The computed ?? for UO?(TMGA)?²?, 950 cm?¹, is essentially the same as that for UO?(TMOGA)?²?, suggesting that electron donation to uranyl from the Oether of TMOGA is minor. The computed ?? asymmetric stretching frequencies for the three actinyl complexes, UO?(TMOGA)?²?, NpO?(TMOGA)?²? and PuO?(TMOGA)?²?, are comparable. This similarity is discussed in the context of the relationship between ?? and intrinsic actinide-oxygen bond energies in actinyl complexes.

  13. Visible-near-infrared luminescent lanthanide ternary complexes based on beta-diketonate using visible-light excitation.

    PubMed

    Sun, Lining; Qiu, Yannan; Liu, Tao; Feng, Jing; Deng, Wei; Shi, Liyi

    2015-11-01

    We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible-light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3 phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401-460 nm), the complexes show characteristic visible (Sm(3+) ) as well as near-infrared (Sm(3+) , Nd(3+) , Yb(3+) , Er(3+) , Tm(3+) , Pr(3+) ) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near-infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25691149

  14. The stepwise multi-photon activation fluorescence guided ablation of melanin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Gu, Zetong; DiMarzio, Charles

    2015-02-01

    Previous research has shown that the stepwise multi-photon activation fluorescence (SMPAF) of melanin, activated and excited by a continuous-wave (CW) mode near infrared (NIR) laser, is a low-cost and reliable method for detecting melanin. We have developed a device utilizing the melanin SMPAF to guide the ablation of melanin with a 975 nm CW laser. This method provides the ability of targeting individual melanin particles with micrometer resolution, and enables localized melanin ablation to be performed without collateral damage. Compared to the traditional selective photothermolysis, which uses pulsed lasers for melanin ablation, this method demonstrates higher precision and lower cost. Therefore, the SMPAF guided selective ablation of melanin is a promising tool of melanin ablation for both medical and cosmetic purposes.

  15. Red-emitting upconverting nanoparticles for photodynamic therapy in cancer cells under near-infrared excitation.

    PubMed

    Tian, Gan; Ren, Wenlu; Yan, Liang; Jian, Shan; Gu, Zhanjun; Zhou, Liangjun; Jin, Shan; Yin, Wenyan; Li, Shoujian; Zhao, Yuliang

    2013-06-10

    Upconverting nanoparticles (UCNPs) have attracted considerable attention as potential photosensitizer carriers for photodynamic therapy (PDT) in deep tissues. In this work, a new and efficient NIR photosensitizing nanoplatform for PDT based on red-emitting UCNPs is designed. The red emission band matches well with the efficient absorption bands of the widely used commercially available photosensitizers (Ps), benefiting the fluorescence resonance energy transfer (FRET) from UCNPs to the attached photosensitizers and thus efficiently activating them to generate cytotoxic singlet oxygen. Three commonly used photosensitizers, including chlorine e6 (Ce6), zinc phthalocyanine (ZnPc) and methylene blue (MB), are loaded onto the alpha-cyclodextrin-modified UCNPs to form Ps@UCNPs complexes that efficiently produce singlet oxygen to kill cancer cells under 980 nm near-infrared excitation. Moreover, two different kinds of drugs are co-loaded onto these nanoparticles: chemotherapy drug doxorubicin and PDT agent Ce6. The combinational therapy based on doxorubicin (DOX)-induced chemotherapy and Ce6-triggered PDT exhibits higher therapeutic efficacy relative to the individual means for cancer therapy in vitro. PMID:23239556

  16. IR multiphoton dissociation dynamics of 2,5-dihydrofuran. Time-resolved observation of concerted furan formation

    NASA Astrophysics Data System (ADS)

    Chowdhury, P. K.; Mittal, J. P.

    1995-08-01

    On infrared multiphoton excitation by a pulsed CO 2 laser, vibrationally excited 2,5-dihydrofuran (DHF) undergoes concerted dissociation generating hydrogen and furan as products. The real time evolution of nascent furan as a photoproduct is monitored. The formation rate of transient vibrationally hot furan, which has an absorption at 245 nm, fits a single exponential with a rate constant (1.8 ± 0.1) × 10 6 s -1. An RRKM calculation for the unimolecular dissociation of DHF gives an average energy of DHF as 70.1 ± 2 kcal/mol corresponding to the experimental rates. The nascent hot furan, with a vibrational temperature of 1816 ± 50 K, exibits a red-shift of 30 nm in the transient absorption spectrum.

  17. Selective enhancement of resonant multiphoton ionization with strong laser fields

    E-print Network

    Li, Min; Luo, Siqiang; Zhou, Yueming; Zhang, Qingbin; Lan, Pengfei; Lu, Peixiang

    2015-01-01

    High-resolution photoelectron momentum distributions of Xe atom ionized by 800-nm linearly polarized laser fields have been traced at intensities from 1.1*1013 W/cm2 to 3.5*1013 W/cm2 using velocity-map imaging techniques. At certain laser intensities, the momentum spectrum exhibits a distinct double-ring structure for low-order above-threshold ionization, which appears to be absent at lower or higher laser intensities. By investigating intensity-resolved photoelectron energy spectrum, we find that this double-ring structure originates from resonant multiphoton ionization involving multiple Rydberg states of atoms. Varying the laser intensity, we can selectively enhance multiphoton excitation of atomic Rydberg populations. The photoelectron angular distributions of multiphoton resonance are also investigated for the low-order above threshold ionization.

  18. High-resolution multimodal clinical multiphoton tomography of skin

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2011-03-01

    This review focuses on multimodal multiphoton tomography based on near infrared femtosecond lasers. Clinical multiphoton tomographs for 3D high-resolution in vivo imaging have been placed into the market several years ago. The second generation of this Prism-Award winning High-Tech skin imaging tool (MPTflex) was introduced in 2010. The same year, the world's first clinical CARS studies have been performed with a hybrid multimodal multiphoton tomograph. In particular, non-fluorescent lipids and water as well as mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen has been imaged with submicron resolution in patients suffering from psoriasis. Further multimodal approaches include the combination of multiphoton tomographs with low-resolution wide-field systems such as ultrasound, optoacoustical, OCT, and dermoscopy systems. Multiphoton tomographs are currently employed in Australia, Japan, the US, and in several European countries for early diagnosis of skin cancer, optimization of treatment strategies, and cosmetic research including long-term testing of sunscreen nanoparticles as well as anti-aging products.

  19. Enhanced thermal radiation in terahertz and far-infrared regime by hot phonon excitation in a field effect transistor

    SciTech Connect

    Chung, Pei-Kang; Yen, Shun-Tung

    2014-11-14

    We demonstrate the hot phonon effect on thermal radiation in the terahertz and far-infrared regime. A pseudomorphic high electron mobility transistor is used for efficiently exciting hot phonons. Boosting the hot phonon population can enhance the efficiency of thermal radiation. The transistor can yield at least a radiation power of 13??W and a power conversion efficiency higher than a resistor by more than 20%.

  20. Generalized Multiphoton Quantum Interference

    NASA Astrophysics Data System (ADS)

    Tillmann, Max; Tan, Si-Hui; Stoeckl, Sarah E.; Sanders, Barry C.; de Guise, Hubert; Heilmann, René; Nolte, Stefan; Szameit, Alexander; Walther, Philip

    2015-10-01

    Nonclassical interference of photons lies at the heart of optical quantum information processing. Here, we exploit tunable distinguishability to reveal the full spectrum of multiphoton nonclassical interference. We investigate this in theory and experiment by controlling the delay times of three photons injected into an integrated interferometric network. We derive the entire coincidence landscape and identify transition matrix immanants as ideally suited functions to describe the generalized case of input photons with arbitrary distinguishability. We introduce a compact description by utilizing a natural basis that decouples the input state from the interferometric network, thereby providing a useful tool for even larger photon numbers.

  1. Pulsed infrared radiation excites cultured neonatal spiral and vestibular ganglion neurons by modulating mitochondrial calcium cycling

    PubMed Central

    Lumbreras, Vicente; Bas, Esperanza; Gupta, Chhavi

    2014-01-01

    Cochlear implants are currently the most effective solution for profound sensorineural hearing loss, and vestibular prostheses are under development to treat bilateral vestibulopathies. Electrical current spread in these neuroprostheses limits channel independence and, in some cases, may impair their performance. In comparison, optical stimuli that are spatially confined may result in a significant functional improvement. Pulsed infrared radiation (IR) has previously been shown to elicit responses in neurons. This study analyzes the response of neonatal rat spiral and vestibular ganglion neurons in vitro to IR (wavelength = 1,863 nm) using Ca2+ imaging. Both types of neurons responded consistently with robust intracellular Ca2+ ([Ca2+]i) transients that matched the low-frequency IR pulses applied (4 ms, 0.25–1 pps). Radiant exposures of ?637 mJ/cm2 resulted in continual neuronal activation. Temperature or [Ca2+] variations in the media did not alter the IR-evoked transients, ruling out extracellular Ca2+ involvement or primary mediation by thermal effects on the plasma membrane. While blockage of Na+, K+, and Ca2+ plasma membrane channels did not alter the IR-evoked response, blocking of mitochondrial Ca2+ cycling with CGP-37157 or ruthenium red reversibly inhibited the IR-evoked [Ca2+]i transients. Additionally, the magnitude of the IR-evoked transients was dependent on ryanodine and cyclopiazonic acid-dependent Ca2+ release. These results suggest that IR modulation of intracellular calcium cycling contributes to stimulation of spiral and vestibular ganglion neurons. As a whole, the results suggest selective excitation of neurons in the IR beam path and the potential of IR stimulation in future auditory and vestibular prostheses. PMID:24920028

  2. Maintaining polarization in polarimetric multiphoton microscopy.

    PubMed

    Bélanger, Erik; Turcotte, Raphaël; Daradich, Amy; Sadetsky, Grégory; Gravel, Pierre; Bachand, Karine; De Koninck, Yves; Côté, Daniel C

    2015-11-01

    Polarimetric measurements in multiphoton microscopy can reveal information about the local molecular order of a sample. However, the presence of a dichroic through which the excitation beam propagates will generally scramble its polarization. We propose a simple scheme whereby a second properly-oriented compensation dichroic is used to negate any alteration regardless of the wavelength and the initial polarization. We demonstrate how this robust and rapid approach simplifies polarimetric measurements in second-harmonic generation, two-photon excited fluorescence and coherent anti-Stokes Raman scattering. Illustration of the polarization maintaining strategy with the compensating dichroic oriented such that its s- and p-axes are interchanged with these of the primary dichroic. PMID:25691172

  3. Acousto-optic multiphoton laser scanning microscopy and multiphoton photon counting spectroscopy: Applications and implications for optical neurobiology

    NASA Astrophysics Data System (ADS)

    Iyer, Vijay

    Multiphoton excitation of molecular probes has become an important tool in experimental neurobiology owing to the intrinsic optical sectioning and low light scattering it affords. Using molecular functional indicators, multiphoton excitation allows physiological signals within single neurons to be observed from within living brain tissue. Ideally, it would be possible to record from multiple sites located throughout the elaborately branching dendritic arbors, in order to study the correlations of structure and function both within and across experiments. However, existing multiphoton microscope systems based on scanning mirrors do not allow optical recordings to be obtained from more than a handful of sites simultaneously at the high rates required to capture the fast physiological signals of interest (>100Hz for Ca2+ signals, >1kHz for membrane potential transients). In order to overcome this limitation, two-dimensional acousto-optic deflection was employed, to allow an ultrafast laser beam suited for multiphoton excitation to be rapidly repositioned with low latency (˜15mus). This supports a random-access scanning mode in which the beam can repeatedly visit a succession of user-selected sites of interest within the microscope's field-of-view at high rates, with minimal sacrifice of pixel dwell time. This technique of acousto-optic multiphoton laser scanning microscope (AO-MPLSM) was demonstrated to allow the spatial profile of signals arising in response to physiological stimulation to be rapidly mapped. Means to compensate or avoid problems of dispersion which have hampered AO-MPLSM in the past are presented, with the latter being implemented. Separately, the combination of photon counting detection with multiphoton excitation, termed generally multiphoton photon counting spectroscopy (MP-PCS), was also considered, with particular emphasis on the technique of fluorescence correlation spectroscopy (FCS). MP-PCS was shown to allow information about molecular numbers and mobility, as well as the focal volume itself, to be obtained. This capability may in the future be employed to study the number and transport of native neuronal signaling molecules. MP-PCS was also found to be a promising off-line tool which can allow the performance of AO-MPLSM to be optimized, with respect to both the instrument and the indicators employed.

  4. Ultrafast excited-state dynamics and fluorescence deactivation of near-infrared fluorescent proteins engineered from bacteriophytochromes

    NASA Astrophysics Data System (ADS)

    Zhu, Jingyi; Shcherbakova, Daria M.; Hontani, Yusaku; Verkhusha, Vladislav V.; Kennis, John T. M.

    2015-08-01

    Near-infrared fluorescent proteins, iRFPs, are recently developed genetically encoded fluorescent probes for deep-tissue in vivo imaging. Their functions depend on the corresponding fluorescence efficiencies and electronic excited state properties. Here we report the electronic excited state deactivation dynamics of the most red-shifted iRFPs: iRFP702, iRFP713 and iRFP720. Complementary measurements by ultrafast broadband fluorescence and absorption spectroscopy show that single exponential decays of the excited state with 600?~?700?ps dominate in all three iRFPs, while photoinduced isomerization was completely inhibited. Significant kinetic isotope effects (KIE) were observed with a factor of ~1.8 in D2O, and are interpreted in terms of an excited-state proton transfer (ESPT) process that deactivates the excited state in competition with fluorescence and chromophore mobility. On this basis, new approaches for rational molecular engineering may be applied to iRFPs to improve their fluorescence.

  5. Ultrafast excited-state dynamics and fluorescence deactivation of near-infrared fluorescent proteins engineered from bacteriophytochromes

    PubMed Central

    Zhu, Jingyi; Shcherbakova, Daria M.; Hontani, Yusaku; Verkhusha, Vladislav V.; Kennis, John T. M.

    2015-01-01

    Near-infrared fluorescent proteins, iRFPs, are recently developed genetically encoded fluorescent probes for deep-tissue in vivo imaging. Their functions depend on the corresponding fluorescence efficiencies and electronic excited state properties. Here we report the electronic excited state deactivation dynamics of the most red-shifted iRFPs: iRFP702, iRFP713 and iRFP720. Complementary measurements by ultrafast broadband fluorescence and absorption spectroscopy show that single exponential decays of the excited state with 600?~?700?ps dominate in all three iRFPs, while photoinduced isomerization was completely inhibited. Significant kinetic isotope effects (KIE) were observed with a factor of ~1.8 in D2O, and are interpreted in terms of an excited-state proton transfer (ESPT) process that deactivates the excited state in competition with fluorescence and chromophore mobility. On this basis, new approaches for rational molecular engineering may be applied to iRFPs to improve their fluorescence. PMID:26246319

  6. Ultrafast excited-state dynamics and fluorescence deactivation of near-infrared fluorescent proteins engineered from bacteriophytochromes.

    PubMed

    Zhu, Jingyi; Shcherbakova, Daria M; Hontani, Yusaku; Verkhusha, Vladislav V; Kennis, John T M

    2015-01-01

    Near-infrared fluorescent proteins, iRFPs, are recently developed genetically encoded fluorescent probes for deep-tissue in vivo imaging. Their functions depend on the corresponding fluorescence efficiencies and electronic excited state properties. Here we report the electronic excited state deactivation dynamics of the most red-shifted iRFPs: iRFP702, iRFP713 and iRFP720. Complementary measurements by ultrafast broadband fluorescence and absorption spectroscopy show that single exponential decays of the excited state with 600~700 ps dominate in all three iRFPs, while photoinduced isomerization was completely inhibited. Significant kinetic isotope effects (KIE) were observed with a factor of ~1.8 in D2O, and are interpreted in terms of an excited-state proton transfer (ESPT) process that deactivates the excited state in competition with fluorescence and chromophore mobility. On this basis, new approaches for rational molecular engineering may be applied to iRFPs to improve their fluorescence. PMID:26246319

  7. Biomedical applications involving multiphoton probes

    NASA Astrophysics Data System (ADS)

    Potasek, M.; Beeson, K.; Parilov, E.

    2015-03-01

    Many techniques in biological and clinical science use multiphoton absorbers for fluorescence. The applications include medical imaging for living cells, diagnostic techniques for disease and spectroscopy. The intrinsic value of the multiphoton absorber coefficients is therefore of the utmost importance. Additionally, the laser intensity at which the absorber saturates can determine which absorber, dye or protein is useful for a particular application. Yet, experimental methods for determining the optical coefficients often yield different results. We describe several common methods of 2PA measurements and describe their features. As an example of the importance of applying the correct analysis to measurements, we fit experimental data and obtain values for multiphoton absorbers and accurately obtain their intrinsic values. Finally, we present the optical properties of several multiphoton materials used in biology.

  8. Development and characterization of non-resonant multiphoton photoacoustic spectroscopy (NMPPAS) for brain tumor margining

    NASA Astrophysics Data System (ADS)

    Dahal, Sudhir

    During tumor removal surgery, due to the problems associated with obtaining high-resolution, real-time chemical images of where exactly the tumor ends and healthy tissue begins (tumor margining), it is often necessary to remove a much larger volume of tissue than the tumor itself. In the case of brain tumor surgery, however, it is extremely unsafe to remove excess tissue. Therefore, without an accurate image of the tumor margins, some of the tumor's finger-like projections are inevitably left behind in the surrounding parenchyma to grow again. For this reason, the development of techniques capable of providing high-resolution real-time images of tumor margins up to centimeters below the surface of a tissue is ideal for the diagnosis and treatment of tumors, as well as surgical guidance during brain tumor excision. A novel spectroscopic technique, non-resonant multiphoton photoacoustic spectroscopy (NMPPAS), is being developed with the capabilities of obtaining high-resolution subsurface chemical-based images of underlying tumors. This novel technique combines the strengths of multiphoton tissue spectroscopy and photoacoustic spectroscopy into a diagnostic methodology that will, ultimately, provide unparalleled chemical information and images to provide the state of sub-surface tissues. The NMPPAS technique employs near-infrared light (in the diagnostic window) to excite ultraviolet and/or visible light absorbing species deep below the tissue's surface. Once a multiphoton absorption event occurs, non-radiative relaxation processes generates a localized thermal expansion and subsequent acoustic wave that can be detected using a piezoelectric transducer. Since NMPPAS employs an acoustic detection modality, much deeper diagnoses can be performed than that is possible using current state of the art high-resolution chemical imaging techniques such as multiphoton fluorescence spectroscopy. NMPPAS was employed to differentiate between excised brain tumors (astrocytoma III) and healthy tissue with over 99% accuracy. NMPPAS spectral features showed evident differences between tumor and healthy tissues, and ratiometric analysis ensured that only a few wavelengths could be used for excitation instead of using numerous wavelength excitations to create spectra. This process would significantly reduce the analysis time while maintaining the same degree of accuracy. Tissue phantoms were fabricated in order to characterize the properties of NMPPAS. Scattering particles were doped into the phantoms to simulate their light scattering properties to real tissues. This allowed for better control over shape, size, reproducibility and doping in the sample while maintaining the light-tissue interaction properties of real tissue. To make NMPPAS viable for clinical applications, the technique was characterized to determine the spatial (lateral and longitudinal) resolution, depth of penetration and its ability to image in three-dimension through layers of tissue. Both resolutions were determined to be near-cellular level resolution (50-70 microm), obtained initially with the aid of the technique of multiphoton fluorescence, and later verified using NMPPAS imaging. Additionally, the maximum depth of penetration and detection was determined to be about 1.4cm, making the technique extremely suitable to margin tumors from underlying tissues in the brain. The capability of NMPPAS to detect and image layers that lie beneath other structures and blood vessels was also investigated. Three-dimensional images were obtained for the first time using NMPPAS. The images were obtained from different depths and structures were imaged through other layers of existing structures in the sample. This verified that NMPPAS was capable of detecting and imaging structures that lie embedded within the tissues. NMPPAS images of embedded structures were also obtained with the presence of hemoglobin, which is potentially the largest source of background in blood-perfused tissues, thus showing that the technique is capable of detecting and differentiating in blood-perfused sam

  9. Terahertz-to-infrared emission through laser excitation of surface plasmons in metal films with porous nanostructures.

    PubMed

    Zhang, Liangliang; Zhao, Ji; Wu, Tong; Zhang, Cunlin; Zhang, X-C

    2015-06-29

    We report on the investigation of terahertz-to-infrared (THz-to-IR) thermal emission that relies on the excitation of surface plasmons in metal films deposited on a substrate with randomly ordered nanoscale pore arrays. The THz-to-IR radiation was observed both in the direction of laser beam propagation and the reverse direction. The intensity ratio between backward and forward radiation is exponentially dependent on the nominal thickness of the porous metal films. The findings are discussed in view of the proposed generation mechanism based on propagating surface plasmon polaritons on both air/metal and metal/substrate interfaces. PMID:26191727

  10. Laser action in chromium-activated forsterite for near-infrared excitation: Is Cr/sup 4 +/ the lasing ion

    SciTech Connect

    Petricevic, V.; Gayen, S.K.; Alfano, R.R.

    1988-12-26

    Room-temperature pulsed laser action has been obtained in chromium-activated forsterite (Cr:Mg/sub 2/SiO/sub 4/) for excitation of the near-infrared absorption band of the system by the 1064 nm radiation from a Nd:YAG laser. The characteristics of laser emission are similar to those observed for 532 nm pumping. It is suggested that the laser action is due to a ''center'' other than the trivalent chromium (Cr/sup 3 +/), presumably the tetravalent chromium (Cr/sup 4 +/).

  11. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the underlying physics. There are now at least six different disciplines that deal with infrared radiation in one form or another, and in one or several different spectral portions of the whole IR range. These are spectroscopy, astronomy, thermal imaging, detector and source development and metrology, as well the field of optical data transmission. Scientists working in these fields range from chemists and astronomers through to physicists and even photographers. This issue presents examples from some of these fields. All the papers—though some of them deal with fundamental or applied research—include interesting elements that make them directly applicable to university-level teaching at the graduate or postgraduate level. Source (e.g. quantum cascade lasers) and detector development (e.g. multispectral sensors), as well as metrology issues and optical data transmission, are omitted since they belong to fundamental research journals. Using a more-or-less arbitrary order according to wavelength range, the issue starts with a paper on the physics of near-infrared photography using consumer product cameras in the spectral range from 800 nm to 1.1 µm [1]. It is followed by a series of three papers dealing with IR imaging in spectral ranges from 3 to 14 µm [2-4]. One of them deals with laboratory courses that may help to characterize the IR camera response [2], the second discusses potential applications for nondestructive testing techniques [3] and the third gives an example of how IR thermal imaging may be used to understand cloud cover of the Earth [4], which is the prerequisite for successful climate modelling. The next two papers cover the vast field of IR spectroscopy [5, 6]. The first of these deals with Fourier transform infrared spectroscopy in the spectral range from 2.5 to 25 µm, studying e.g. ro-vibrational excitations in gases or optical phonon interactions within solids [5]. The second deals mostly with the spectroscopy of liquids such as biofuels and special techniques such as attenuated total reflectance [6]. The two final papers deal with what se

  12. Optical and Near Infrared Study of the Cepheus E Outflow, a Very Low Excitation Object

    NASA Technical Reports Server (NTRS)

    Noreiga-Crespo, A.; Ayala, S.; Garnavich, P.; Curiel, S.; Raga, A.; Bohm, K.; Raymond, J.

    2000-01-01

    In this study, we explore the link between the physical properties of the outflow as determined from optical imaging and spectroscopy, and compare these results with those obtained from observations in the near infrared.

  13. Comparison of objective lenses for multiphoton microscopy in turbid samples

    PubMed Central

    Singh, Avtar; McMullen, Jesse D.; Doris, Eli A.; Zipfel, Warren R.

    2015-01-01

    Optimization of illumination and detection optics is pivotal for multiphoton imaging in highly scattering tissue and the objective lens is the central component in both of these pathways. To better understand how basic lens parameters (NA, magnification, field number) affect fluorescence collection and image quality, a two-detector setup was used with a specialized sample cell to separate measurement of total excitation from epifluorescence collection. Our data corroborate earlier findings that low-mag lenses can be superior at collecting scattered photons, and we compare a set of commonly used multiphoton objective lenses in terms of their ability to collect scattered fluorescence, providing guidance for the design of multiphoton imaging systems. For example, our measurements of epi-fluorescence beam divergence in the presence of scattering reveal minimal beam broadening, indicating that often-advocated over-sized collection optics are not as advantageous as previously thought. These experiments also provide a framework for choosing objective lenses for multiphoton imaging by relating the results of our measurements to various design parameters of the objectives lenses used. PMID:26309771

  14. Infrared multiphoton dissociation of two perfluorobutenes

    E-print Network

    Longfellow, Cheryl A.; Berrie, Cindy L.; Suits, Arthur G.; Lee, Yuan T.

    1997-08-04

    Measurements were taken at detector to source angles of 15°, 20°, 30°, 40°, and 50°. Dissociation signal was observed at a large number of m/e ratios. The fragmentation of fluo- rocarbon species in the electron impact ionizer was signifi- cant. In a typical.... This assignment be- comes more difficult if each m/e ratio contains contributions from the dissociative ionization of numerous products. In addition, there are fluorocarbons that fragment so extensively in the electron impact ionization that no parent survives. CF...

  15. Laser action in chromium-activated forsterite for near infrared excitation

    NASA Technical Reports Server (NTRS)

    Petricevic, V.; Gayen, S. K.; Alfano, R. R.

    1988-01-01

    This paper reports on laser action in chromium-doped forsterite (Cr:Mg2SiO4) for 1064-nm excitation of the crystal's double-hump absorption band spanning the 850-1200-nm wavelength range. The cavity arrangement used for obtaining laser action in Cr:Mg2SiO2 was similar to that described by Petricevic et al. (1988). The fundamental and second harmonic emissions from a Q-switched Nd:YAG laser operating at a 10-Hz repetition rate were used for excitation of the NIR and visible bands, respectively. Pulsed laser action was readily observed for both the 1064-nm and 532-nm pumping at or above the respective thresholds. The laser parameters of the 532-nm and 1064-nm excitations were similar, indicating that the IR band is responsible for laser action for both excitations.

  16. High-throughput multiphoton-induced three-dimensional ablation and imaging for biotissues

    PubMed Central

    Lin, Chun-Yu; Li, Pei-Kao; Cheng, Li-Chung; Li, Yi-Cheng; Chang, Chia-Yuan; Chiang, Ann-Shyn; Dong, Chen Yuan; Chen, Shean-Jen

    2015-01-01

    In this study, a temporal focusing-based high-throughput multiphoton-induced ablation system with axially-resolved widefield multiphoton excitation has been successfully applied to rapidly disrupt biotissues. Experimental results demonstrate that this technique features high efficiency for achieving large-area laser ablation without causing serious photothermal damage in non-ablated regions. Furthermore, the rate of tissue processing can reach around 1.6 × 106 ?m3/s in chicken tendon. Moreover, the temporal focusing-based multiphoton system can be efficiently utilized in optical imaging through iterating high-throughput multiphoton-induced ablation machining followed by widefield optical sectioning; hence, it has the potential to obtain molecular images for a whole bio-specimen. PMID:25780739

  17. Multiphoton nanosurgery in cells and tissues

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Anhut, Tiemo; Stracke, Frank; Le Harzic, Ronan; Koenig, Karsten

    2005-04-01

    Multiphoton Microscopy with a femtosecond pulsed Ti:sapphire laser in the near infrared (NIR) enables the user not only to image cells and tissues with a subcellular resolution but also to perform highly precise nanosurgery. Intratissue compartments, single cells and even cell organelles like mitochondria, membranes or chromosomes can be manipulated and optically knocked out. Working at transient TW/cm2 laser intensities, single cells of tumor-sphaeroids were eliminated efficiently inside the sphaeroid without damaging the neighbour cells. Also single organelles of cells inside tissues could be optically knocked out with the nanoscalpel without collateral damage. Tissue structures inside a human tooth have been ablated with sizes below 1 ?m. This method may become a useful instrument for nano-manipulating and surgery in several fields of science, including targeted transfection.

  18. Attosecond x-ray sources generation from pre-excited He+ ions using mid-infrared homogeneous and inhomogeneous fields

    NASA Astrophysics Data System (ADS)

    Feng, Liqiang; Liu, Hang

    2015-10-01

    A promising method is proposed to generate the intense ultrabroadband supercontinuum spectra and the ultrashort attosecond x-ray pulses from pre-excited He+ ion with the homogeneous and inhomogeneous two-color mid-infrared laser field combined with a unipolar pulse. For the homogeneous case, by optimizing the two mid-infrared pulses and the unipolar pulse, not only the harmonic cutoff has been extended, but also the harmonic modulation has been remarkably reduced. Moreover, we found the above harmonic extension scheme can be achieved in the multi-cycle pulse region and by preparing the initial state of He+ ion as the coherent superposition of the ground and the first excited states, the harmonic yield can be enhanced by 4-6 orders of magnitude compared with the case of the single ground initial state. Furthermore, with the introduction of the inhomogeneous of the combined field, the harmonic cutoff can be further enhanced, resulting in a supercontinuum with the bandwidth of 1648?eV. As a result, a series of intense 32as x-ray pulses can be obtained, which are 4-6 orders of magnitude improvement in comparison with the single initial state case.

  19. Quantitative multiphoton imaging

    NASA Astrophysics Data System (ADS)

    König, Karsten; Weinigel, Martin; Breunig, Hans Georg; Uchugonova, Aisada

    2014-02-01

    Certified clinical multiphoton tomographs for label-free multidimensional high-resolution in vivo imaging have been introduced to the market several years ago. Novel tomographs include a flexible 360° scan head attached to a mechanooptical arm for autofluorescence and SHG imaging as well as a CARS module. Non-fluorescent lipids and water, mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged in vivo with submicron resolution in human skin. Sensitive and rapid detectors allow single photon counting and the construction of 3D maps where the number of detected photons per voxel is depicted. Intratissue concentration profiles from endogenous as well exogenous substances can be generated when the number of detected photons can be correlated with the number of molecules with respect to binding and scattering behavior. Furthermore, the skin ageing index SAAID based on the ratio elastin/collagen as well as the epidermis depth based on the onset of SHG generation can be determined.

  20. Multiphoton tomography of astronauts

    NASA Astrophysics Data System (ADS)

    König, Karsten; Weinigel, Martin; Pietruszka, Anna; Bückle, Rainer; Gerlach, Nicole; Heinrich, Ulrike

    2015-03-01

    Weightlessness may impair the astronaut's health conditions. Skin impairments belong to the most frequent health problems during space missions. Within the Skin B project, skin physiological changes during long duration space flights are currently investigated on three European astronauts that work for nearly half a year at the ISS. Measurements on the hydration, the transepidermal water loss, the surface structure, elasticity and the tissue density by ultrasound are conducted. Furthermore, high-resolution in vivo histology is performed by multiphoton tomography with 300 nm spatial and 200 ps temporal resolution. The mobile certified medical tomograph with a flexible 360° scan head attached to a mechano-optical arm is employed to measure two-photon autofluorescence and SHG in the volar forearm of the astronauts. Modification of the tissue architecture and of the fluorescent biomolecules NAD(P)H, keratin, melanin and elastin are detected as well as of SHG-active collagen. Thinning of the vital epidermis, a decrease of the autofluoresence intensity, an increase in the long fluorescence lifetime, and a reduced skin ageing index SAAID based on an increased collagen level in the upper dermis have been found. Current studies focus on recovery effects.

  1. Mitigating Phototoxicity during Multiphoton Microscopy of Live Drosophila Embryos in the 1.0–1.2 µm Wavelength Range

    PubMed Central

    Débarre, Delphine; Olivier, Nicolas; Supatto, Willy; Beaurepaire, Emmanuel

    2014-01-01

    Light-induced toxicity is a fundamental bottleneck in microscopic imaging of live embryos. In this article, after a review of photodamage mechanisms in cells and tissues, we assess photo-perturbation under illumination conditions relevant for point-scanning multiphoton imaging of live Drosophila embryos. We use third-harmonic generation (THG) imaging of developmental processes in embryos excited by pulsed near-infrared light in the 1.0–1.2 µm range. We study the influence of imaging rate, wavelength, and pulse duration on the short-term and long-term perturbation of development and define criteria for safe imaging. We show that under illumination conditions typical for multiphoton imaging, photodamage in this system arises through 2- and/or 3-photon absorption processes and in a cumulative manner. Based on this analysis, we derive general guidelines for improving the signal-to-damage ratio in two-photon (2PEF/SHG) or THG imaging by adjusting the pulse duration and/or the imaging rate. Finally, we report label-free time-lapse 3D THG imaging of gastrulating Drosophila embryos with sampling appropriate for the visualisation of morphogenetic movements in wild-type and mutant embryos, and long-term multiharmonic (THG-SHG) imaging of development until hatching. PMID:25111506

  2. Evaluation of Barrett Esophagus by Multiphoton Microscopy

    PubMed Central

    Chen, Jianxin; Wong, Serena; Nathanson, Michael H.; Jain, Dhanpat

    2014-01-01

    Context Multiphoton microscopy (MPM) based on 2-photon excitation fluorescence and second-harmonic generation allows simultaneous visualization of cellular details and extracellular matrix components of fresh, unfixed, and unstained tissue. Portable multiphoton microscopes, which could be placed in endoscopy suites, and multiphoton endomicroscopes are in development, but their clinical utility is unknown. Objectives To examine fresh, unfixed endoscopic biopsies obtained from the distal esophagus and gastroesophageal junction to (1) define the MPM characteristics of normal esophageal squamous mucosa and gastric columnar mucosa, and (2) evaluate whether diagnosis of intestinal metaplasia/Barrett esophagus (BE) could be made reliably with MPM. Design The study examined 35 untreated, fresh biopsy specimens from 25 patients who underwent routine upper endoscopy. A Zeiss LSM 710 Duo microscope (Carl Zeiss, Thornwood, New York) coupled to a Spectra-Physics (Mountain View, California) Tsunami Ti:sapphire laser was used to obtain a MPM image within 4 hours of fresh specimen collection. After obtaining MPM images, the biopsy specimens were placed in 10% buffered formalin and submitted for routine histopathologic examination. Then, the MPM images were compared with the findings in the hematoxylin-eosin–stained, formalin-fixed, paraffin-embedded sections. The MPM characteristics of the squamous, gastric-type columnar and intestinal-type columnar epithelium were analyzed. In biopsies with discrepancy between MPM imaging and hematoxylin-eosin–stained sections, the entire tissue block was serially sectioned and reevaluated. A diagnosis of BE was made when endoscopic and histologic criteria were satisfied. Results Based on effective 2-photon excitation fluorescence of cellular reduced pyridine nucleotides and flavin adenine dinucleotide and lack of 2-photon excitation fluorescence of mucin and cellular nuclei, MPM could readily identify and distinguish among squamous epithelial cells, goblet cells, gastric foveolar-type mucous cells, and parietal cells in the area of gastroesophageal junction. Based on the cell types identified, the mucosa was defined as squamous, columnar gastric type (cardia/fundic-type), and metaplastic columnar intestinal-type/BE. Various types of mucosa seen in the study of 35 biopsies included normal squamous mucosa only (n = 14; 40%), gastric cardia-type mucosa only (n = 2; 6%), gastric fundic mucosa (n = 6; 17%), and both squamous and gastric mucosa (n = 13; 37%). Intestinal metaplasia was identified by the presence of goblet cells in 10 of 25 cases (40%) leading to a diagnosis of BE on MPM imaging and only in 7 cases (28%) by histopathology. In 3 of 35 biopsies (9%), clear-cut goblet cells were seen by MPM imaging but not by histopathology, even after the entire tissue block was sectioned. Based on effective 2-photon excitation fluorescence of elastin and second-harmonic generation of collagen, connective tissue in the lamina propria and the basement membrane was also visualized with MPM. Conclusions Multiphoton microscopy has the ability to accurately distinguish squamous epithelium and different cellular elements of the columnar mucosa obtained from biopsies around the gastroesophageal junction, including goblet cells that are important for the diagnosis of BE. Thus, use of MPM in the endoscopy suite might provide immediate microscopic images during endoscopy, improving screening and surveillance of patients with BE. PMID:24476518

  3. Multiphoton microscopic imaging of rabbit dorsal skin.

    PubMed

    Zhu, Xiaoqin; Xu, Yahao; Hong, Zhipeng; Chen, Jing; Zhuo, Shuangmu; Chen, Jianxin

    2015-01-01

    Rabbits are often preferred to be experimental animals during the skin research. The visualizing and understanding the full-thickness structure of rabbit skin has significance in biology, medicine, and animal husbandry. In this study, multiphoton microscopy (MPM) was employed to examine the rabbit skin on the back, which was based on second harmonic generation and two-photon excited fluorescence. High-resolution images were achieved from the fresh, unfixed, and unstained tissues, showing detailed microstructure of the skin without the administration of exogenous contrast agents. The morphology and distribution of the main components of epidermis and dermis, such as keratin, collagen fibers, elastic fibers, and hair follicles, can be distinctly identified in MPM images. Since the changes in these components are tightly related to skin diseases and wound healing, the noninvasive nature of MPM enables it become a valuable tool in skin research for detecting and monitoring. PMID:25521496

  4. Spin state transitions upon visible and infrared excitation of ferric MbN3

    NASA Astrophysics Data System (ADS)

    Helbing, Jan

    2012-03-01

    When azide binds to ferric Myoglobin it forms either a low-spin or a high-spin complex, which give rise to two well-separated asymmetric stretch bands of the ligand. Both electronic excitation of the Q-band and vibrational excitation of N3- in the mid-IR lead to a similar ultrafast population redistribution in favor of the high spin configuration, which is characterized by a 8° reorientation of the ligand transition dipole moment. The more stable low spin complex subsequently re-emerges with a 18 ps time-constant. It is argued that the observed spin state changes are caused by the participation of low-lying electronic excitations in the cooling process of heme.

  5. R-matrix Floquet theory of multiphoton processes: XIII. Resonances in ? multiphoton detachment

    NASA Astrophysics Data System (ADS)

    van der Hart, H. W.; Fearnside, A. S.

    1997-12-01

    The results of calculations investigating the effects of autodetaching resonances on the multiphoton detachment spectra of 0953-4075/30/24/007/img6 are presented. The R-matrix Floquet method is used, in which the coupling of the ion with the laser field is described non-perturbatively. The laser field is fixed at an intensity of 0953-4075/30/24/007/img7, while frequency ranges are chosen such that the lowest autodetaching states of the ion are excited through a two- or three-photon transition from the ground state. Detachment rates are compared, where possible, to previous results obtained using perturbation theory. An illustration of how non-lowest-order processes, involving autodetaching states, can lead to light-induced continuum structures is also presented. Finally, it is demonstrated that by using a frequency connecting the 1s and 2s states, the probability of exciting the residual hydrogen atom is significantly enhanced.

  6. Photoacoustic imaging of a near-infrared fluorescent marker based on dual wavelength pump-probe excitation

    NASA Astrophysics Data System (ADS)

    Märk, Julia; Theiss, Christoph; Schmitt, Franz-Josef; Laufer, Jan

    2014-03-01

    Photoacoustic imaging has been used to determine the spatial distribution of fluorophores, such as exogenous dyes and genetically expressed proteins, from images acquired in phantoms and in vivo. Most methods involve the acquisition of multiwavelength images and rely on differences in the absorption spectra of the tissue chromophores to estimate the spatial distribution and abundance of the latter using spectral decomposition techniques, such as model based inversion schemes. However, the inversion of 3-D images can be computationally expensive. Experimental approaches to localising contrast agents may therefore be useful, especially if quantification is not essential. This work aims to develop a method for determining the spatial distribution of a near-infrared fluorescent cell marker from images acquired using dual wavelength excitation. The excitation wavelengths coincided with the absorption and emission spectrum of the fluorophore. The contrast mechanism relies on reducing the excited state lifetime of the fluorophore by inducing stimulated emission. This changes the amount of energy thermalized by the fluorophore, and hence the photoacoustic signal amplitude. Since this is not observed in endogenous chromophores, the background may be removed by subtracting two images acquired with and without pulse delay between the pump and probe pulses. To characterise the fluorophore, the signal amplitude is measured in a cuvette as a function of pulse delay, concentration, and fluence. The spatial distribution of the fluorophore is determined from images acquired in realistic tissue phantoms. This method may be suitable for in vivo applications, such as imaging of exogenous or genetically expressed fluorescent cell markers.

  7. Advances in multiphoton microscopy technology

    PubMed Central

    Hoover, Erich E.; Squier, Jeff A.

    2013-01-01

    Multiphoton microscopy has enabled unprecedented dynamic exploration in living organisms. A significant challenge in biological research is the dynamic imaging of features deep within living organisms, which permits the real-time analysis of cellular structure and function. To make progress in our understanding of biological machinery, optical microscopes must be capable of rapid, targeted access deep within samples at high resolution. In this Review, we discuss the basic architecture of a multiphoton microscope capable of such analysis and summarize the state-of-the-art technologies for the quantitative imaging of biological phenomena. PMID:24307915

  8. Infrared/ultraviolet quadruple resonance spectroscopy to investigate structures of electronically excited states

    SciTech Connect

    Weiler, M.; Bartl, K.; Gerhards, M.

    2012-03-21

    Molecular beam investigations in combination with IR/UV spectroscopy offer the possibility to obtain structural information on isolated molecules and clusters. One of the demanding tasks is the discrimination of different isomers, e.g., by the use of isomer specific UV excitations. If this discrimination fails due to overlaying UV spectra of different isomers, IR/IR methods offer another possibility. Here, we present a new IR/UV/IR/UV quadruple resonance technique to distinguish between different isomers especially in the electronically excited state. Due to the IR spectra, structural changes and photochemical pathways in excited states can be assigned and identified. The method is applied to the dihydrated cluster of 3-hydroxyflavone which has been investigated as photochemically relevant system and proton wire model in the S{sub 1} state. By applying the new IR/UV/IR/UV technique, we are able to show experimentally that both in the electronic ground (S{sub 0}) and the electronically excited state (S{sub 1}) two isomers have to be assigned.

  9. Controlled Au-Polymer Nanostructures for Multiphoton Imaging, Prodrug Delivery, and Chemo-Photothermal Therapy Platforms.

    PubMed

    Huang, Chih-Chia; Liu, Tzu-Ming

    2015-11-18

    We have successfully introduced a proton-induced controlled reaction of HAuCl4 and poly(styrene-alt-maleic acid) (PSMA) sodium salt to prepare triangular and multicore Au@polymer nanoparticles (NPs). The interparticle interactions in the core gave rise to an absorption band at the near-infrared wavelength. The near-infrared optical properties of the resulting Au-polymer nanostructures are highly stable in a physiological environment, which offered strong photo-to-thermal conversion by a moderate continuous-wave 808 nm laser and exhibited multiphoton fluorescence for imaging using a 1230 nm light excitation (femtosecond laser). Exposure of the carboxylate groups at the polymer shell made the surface structure of the Au multicore @polymer NPs directly conjugate Pt(II)-/Pt(IV)-based drugs, which possessed the elimination of the immediate toxicity over the short time and resulted in an anticancer effect after 3 days. A synergistic effect of the chemo-photothermal therapy showed a moderate hyperthermia assistance (<1 W/cm(2)) and better anticancer performance over time compared with the individual treatments. We demonstrated that such PSMA-based methodology not only enables a broad range of chemical material synthesis in the kinetic control to form Au nano-octahedrons and nanotriangles using Br(-)/I(-) ions additives but also could be extended to form Au/Fe3O4@polymer nanocomposites via proton-assisted PSMA self-assembly. PMID:26501876

  10. Differentiation of normal and cancerous lung tissues by multiphoton imaging

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Chin; Li, Feng-Chieh; Wu, Ruei-Jhih; Hovhannisyan, Vladimir A.; Lin, Wei-Chou; Lin, Sung-Jan; So, Peter T. C.; Dong, Chen-Yuan

    2009-07-01

    We utilize multiphoton microscopy for the label-free diagnosis of noncancerous, lung adenocarcinoma (LAC), and lung squamous cell carcinoma (SCC) tissues from humans. Our results show that the combination of second-harmonic generation (SHG) and multiphoton excited autofluorescence (MAF) signals may be used to acquire morphological and quantitative information in discriminating cancerous from noncancerous lung tissues. Specifically, noncancerous lung tissues are largely fibrotic in structure, while cancerous specimens are composed primarily of tumor masses. Quantitative ratiometric analysis using MAF to SHG index (MAFSI) shows that the average MAFSI for noncancerous and LAC lung tissue pairs are 0.55+/-0.23 and 0.87+/-0.15, respectively. In comparison, the MAFSIs for the noncancerous and SCC tissue pairs are 0.50+/-0.12 and 0.72+/-0.13, respectively. Our study shows that nonlinear optical microscopy can assist in differentiating and diagnosing pulmonary cancer from noncancerous tissues.

  11. Multiphoton microscopy based cryo-imaging of inflated frozen human lung sections at -60°C in healthy and COPD lungs

    NASA Astrophysics Data System (ADS)

    Abraham, Thomas; Kayra, Damian; Zhang, Angela; Suzuki, Masaru; McDonough, John; Elliott, W. M.; Cooper, Joel D.; Hogg, James C.

    2013-02-01

    Lung is a complex gas exchanger with interfacial area (where the gas exchange takes place) is about the size of a tennis court. Respiratory function is linked to the biomechanical stability of the gas exchange or alveolar regions which directly depends on the spatial distributions of the extracellular matrix fibers such fibrillar collagens and elastin fibers. It is very important to visualize and quantify these fibers at their native and inflated conditions to have correct morphometric information on differences between control and diseased states. This can be only achieved in the ex vivo states by imaging directly frozen lung specimens inflated to total lung capacity. Multiphoton microscopy, which uses ultra-short infrared laser pulses as the excitation source, produces multiphoton excitation fluorescence (MPEF) signals from endogenously fluorescent proteins (e.g. elastin) and induces specific second harmonic generation (SHG) signals from non-centrosymmetric proteins such as fibrillar collagens in fresh human lung tissues [J. Struct. Biol. (2010)171,189-196]. Here we report for the first time 3D image data obtained directly from thick frozen inflated lung specimens (~0.7- 1.0 millimeter thick) visualized at -60°C without prior fixation or staining in healthy and diseased states. Lung specimens donated for transplantation and released for research when no appropriate recipient was identified served as controls, and diseased lung specimens donated for research by patients receiving lung transplantation for very severe COPD (n=4) were prepared as previously described [N. Engl. J. Med. (2011) 201, 1567]. Lung slices evenly spaced between apex and base were examined using multiphoton microscopy while maintained at -60°C using a temperature controlled cold stage with a temperature resolution of 0.1°C. Infrared femto-second laser pulses tuned to 880nm, dry microscopic objectives, and non-de-scanned detectors/spectrophotometer located in the reflection geometry were used for generating the 3D images/spectral information. We found that this novel imaging approach can provide spatially resolved 3D images with spectral specificities from frozen inflated lungs that are sensitive enough to identity the micro-structural details of fibrillar collagens and elastin fibers in alveolar walls in both healthy and diseased tissues.

  12. Multiphoton Quantum Optics and Quantum State Engineering

    E-print Network

    F. Dell'Anno; S. De Siena; F. Illuminati

    2007-01-09

    We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states, macroscopic superposition states, and multiphoton generalized coherent states. We introduce and discuss the structure of canonical multiphoton quantum optics and the associated one- and two-mode canonical multiphoton squeezed states. This framework provides a consistent multiphoton generalization of two-photon quantum optics and a consistent Hamiltonian description of multiphoton processes associated to higher-order nonlinearities. Finally, we discuss very recent advances that by combining linear and nonlinear optical devices allow to realize multiphoton entangled states of the electromnagnetic field, that are relevant for applications to efficient quantum computation, quantum teleportation, and related problems in quantum communication and information.

  13. Luminescence quenching of conductive Si nanocrystals via “Linkage emission”: Hopping-like propagation of infrared-excited Auger electrons

    SciTech Connect

    Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce; Knights, Andrew P.; Gwilliam, Russell M.

    2014-08-14

    Phosphorus (P) is an n-type dopant for conductive silicon nanocrystals (Si-nc's), the electrical activation of which may be monitored through a non-radiative Auger recombination process that quenches the Si-nc luminescence. We investigated this quenching mechanism through electrical measurements of Si-nc's. Infrared-excited Auger electron emission as the non-radiative process was directly probed and the dynamics of the process are determined from a frequency response analysis. To explain the dynamics, we propose a model in which Auger electrons with a low kinetic energy establish a local inter-nanocrystal conductance and the repetition of this local conductance results in a constant photocurrent (“linkage emission”). This emission becomes significant by electron filling in the Si-nc's owing to the electrical activation of P, which is consistent with observed luminescence quenching behavior. We found that the IR photo-excited emission is distinct from the thermally induced hopping conduction and show that confined, rather than trapped, charges are the source of the Auger electrons. Thus, the process consumes both confined charges and the recombination energy for Auger emission, which explains the luminescence quenching mechanism of Si-nc:P.

  14. Non-perturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

    E-print Network

    Li, Guihua; Li, Ziting; Yao, Jingpin; Zeng, Bin; Chu, Wei; Cheng, Ya

    2015-01-01

    We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the driver laser pulses indicate its non-perturbative characteristic.

  15. Multiphoton Magnetooptical Trap

    SciTech Connect

    Wu Saijun; Plisson, Thomas; Brown, Roger C.; Phillips, William D.; Porto, J. V.

    2009-10-23

    We demonstrate a magnetooptical trap (MOT) configuration which employs optical forces due to light scattering between electronically excited states of the atom. With the standard MOT laser beams propagating along the x and y directions, the laser beams along the z direction are at a different wavelength that couples two sets of excited states. We demonstrate efficient cooling and trapping of cesium atoms in a vapor cell and sub-Doppler cooling on both the red and blue sides of the two-photon resonance. The technique demonstrated in this work may have applications in background-free detection of trapped atoms, and in assisting laser cooling and trapping of certain atomic species that require cooling lasers at inconvenient wavelengths.

  16. Development of infrared sensors using energy transfer/energy upconversion processes: Study of laser excited fluorescence in rare Earth ion doped crystals

    NASA Technical Reports Server (NTRS)

    Nash-Stevenson, S. K.; Reddy, B. R.; Venkateswarlu, P.

    1994-01-01

    A summary is presented of the spectroscopic study of three systems: LaF3:Ho(3+), LaF3:Er(3+) and CaF2:Nd(3+). When the D levels of Ho(3+) in LaF3 were resonantly excited with a laser beam of 640 nm, upconverted emissions were detected from J (416 nm), F (485 nm), and E (546 nm) levels. Energy upconverted emissions were also observed from F and E levels of Ho(3+) when the material was excited with an 800 nm near infrared laser. When the D levels of Er(3+) in LaF3 were resonantly excited with a laser beam of 637 nm, upconverted emissions were detected from the E (540 nm) and P (320, 400, and 468 nm) levels. Energy upconverted emissions were also observed from F, E, and D levels of Er(3+) when the material was resonantly excited with an 804 nm near infrared laser. When the D levels of Nd(3+) in CaF2 were resonantly excited with a laser beam of 577 nm, upconverted emissions were detected from the L (360 and 382 nm), K (418 nm), and I (432 nm) levels. Very weak upconverted emissions were detected when this system was irradiated with a near infrared laser. The numbers in parentheses are the wavelengths of the emissions.

  17. Interpretation of rotationally excited far-infrared OH emission in Orion-KL

    NASA Technical Reports Server (NTRS)

    Melnick, G. J.; Genzel, R.; Lugten, J. B.

    1987-01-01

    The 2Pi(1/2) OH 163-micron J = 3/2-1/2 rotational transitions in Orion-KL were observed and an upper limit was set to the line strength of the 2II(1/2) OH 56-micron J = 9/2-7/2 doublet in this source. The 163-micron line intensities were modeled, along with the previously measured 2II(3/2) 119 and 84-micron rotational line emission and it is found that the gas in the Orion-KL postshocked region can produce OH 119-micron line emission of the same strength as measured; however, the resultant 84 and 163-micron line intensities would be weaker than observed. Shocked gas plus a second component which experiences strong radiative excitation can reproduce the observations.

  18. Population transfer by multiphoton adiabatic rapid passage

    SciTech Connect

    Maeda, H.; Gurian, J. H.; Gallagher, T. F.

    2011-03-15

    The population of atoms in Rydberg states is efficiently transferred with a change in principal quantum number n of up to ten via multiphoton adiabatic rapid passage through a single multiphoton resonance using a frequency-chirped microwave pulse. A quantum-mechanical picture of multiphoton adiabatic rapid passage in a one-dimensional atom using a Floquet approach provides a good description of most, but not all, of the observed phenomena.

  19. Measurement of molecular diffusion in solution by multiphoton fluorescence photobleaching recovery

    PubMed Central

    Brown, EB; Wu, ES; Zipfel, W; Webb, WW

    1999-01-01

    Multiphoton fluorescence photobleaching recovery (MP-FPR) is a technique for measuring the three-dimensional (3D) mobility of fluorescent molecules with 3D spatial resolution of a few microns. A brief, intense flash of mode-locked laser light pulses excites fluorescent molecules via multiphoton excitation in an ellipsoidal focal volume and photobleaches a fraction. Because multiphoton excitation of fluorophores is intrinsically confined to the high-intensity focal volume of the illuminating beam, the bleached region is restricted to a known, three-dimensionally defined volume. Fluorescence in this focal volume is measured with multiphoton excitation, using the attenuated laser beam to measure fluorescence recovery as fresh unbleached dye diffuses in. The time course of the fluorescence recovery signal after photobleaching can be analyzed to determine the diffusion coefficient of the fluorescent species. The mathematical formulas used to fit MP-FPR recovery curves and the techniques needed to properly utilize them to acquire the diffusion coefficients of fluorescently labeled molecules within cells are presented here. MP-FPR is demonstrated on calcein in RBL-2H3 cells, using an anomalous subdiffusion model, as well as in aqueous solutions of wild-type green fluorescent protein, yielding a diffusion coefficient of 8.7 x 10(-7) cm(2)s(-1) in excellent agreement with the results of other techniques. PMID:10545381

  20. Femtosecond laser pulse optimization for multiphoton cytometry and control of fluorescence

    NASA Astrophysics Data System (ADS)

    Tkaczyk, Eric Robert

    This body of work encompasses optimization of near infrared femtosecond laser pulses both for enhancement of flow cytometry as well as adaptive pulse shaping to control fluorescence. A two-photon system for in vivo flow cytometry is demonstrated, which allows noninvasive quantification of circulating cell populations in a single live mouse. We monitor fluorescently-labeled red blood cells for more than two weeks, and are also able to noninvasively measure circulation times of two distinct populations of breast cancer cells simultaneously in a single mouse. We build a custom laser excitation source in the form of an extended cavity mode-locked oscillator, which enables superior detection in whole blood or saline of cell lines expressing fluorescent proteins including the green fluorescent protein (GFP), tdTomato and mPlum. A mathematical model explains unique features of the signals. The ability to distinguish different fluorescent species is central to simultaneous measurement of multiple molecular targets in high throughput applications including the multiphoton flow cytometer. We demonstrate that two dyes which are not distinguishable to one-photon measurements can be differentiated and in fact quantified in mixture via phase-shaped two-photon excitation pulses found by a genetic algorithm. We also selectively enhance or suppress two-photon fluorescence of numerous common dyes with tailored pulse shapes. Using a multiplicative (rather than ratiometric) fitness parameter, we are able to control the fluorescence while maintaining a strong signal. With this method, we control the two-photon fluorescence of the blue fluorescent protein (BFP), which is of particular interest in investigations of protein-protein interactions, and has frustrated previous attempts of control. Implementing an acousto-optic interferometer, we use the same experimental setup to measure two-photon excitation cross-sections of dyes and prove that photon-photon interferences are the predominant mechanism of control. This research establishes the basis for molecularly tailored pulse shaping in multiphoton flow cytometry, which will advance our ability to probe the biology of circulating cells during disease progression and response to therapy.

  1. Stochastic scanning multiphoton multifocal microscopy.

    PubMed

    Jureller, Justin E; Kim, Hee Y; Scherer, Norbert F

    2006-04-17

    Multiparticle tracking with scanning confocal and multiphoton fluorescence imaging is increasingly important for elucidating biological function, as in the transport of intracellular cargo-carrying vesicles. We demonstrate a simple rapid-sampling stochastic scanning multifocal multiphoton microscopy (SS-MMM) fluorescence imaging technique that enables multiparticle tracking without specialized hardware at rates 1,000 times greater than conventional single point raster scanning. Stochastic scanning of a diffractive optic generated 10x10 hexagonal array of foci with a white noise driven galvanometer yields a scan pattern that is random yet space-filling. SS-MMM creates a more uniformly sampled image with fewer spatio-temporal artifacts than obtained by conventional or multibeam raster scanning. SS-MMM is verified by simulation and experimentally demonstrated by tracking microsphere diffusion in solution. PMID:19516485

  2. Zero kinetic energy photoelectron spectroscopy of jet cooled benzo[a]pyrene from resonantly enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Harthcock, Colin; Han, Fangyuan; Kong, Wei

    2011-12-01

    We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[a]pyrene (BaP) via resonantly enhanced multiphoton ionization (REMPI). Our analysis concentrates on the vibrational modes of the first excited state (S1) and those of the ground cationic state (D0). Similar to pyrene, another peri-condensed polycyclic aromatic hydrocarbon we have investigated, the first two electronically excited states of BaP exhibit extensive configuration interactions. However, the two electronic states are of the same symmetry, hence vibronic coupling does not introduce any out-of-plane modes in the REMPI spectrum, and Franck-Condon analysis is qualitatively satisfactory. The ZEKE spectra from the in-plane modes observed in the REMPI spectrum demonstrate strong propensity in preserving the vibrational excitation of the intermediate state. Although several additional bands in combination with the vibrational mode of the intermediate state are identifiable, they are much lower in intensity. This observation implies that the molecular structure of BaP has a tremendous capability to accommodate changes in charge density. All observed bands of the cation are IR active, establishing the role of ZEKE spectroscopy in mapping out far infrared bands for astrophysical applications.

  3. Differentiation of normal and cancerous lung tissues by multiphoton imaging

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Chin; Li, Feng-Chieh; Wu, Ruei-Jr; Hovhannisyan, Vladimir A.; Lin, Wei-Chou; Lin, Sung-Jan; So, Peter T. C.; Dong, Chen-Yuan

    2010-02-01

    In this work, we utilized multiphoton microscopy for the label-free diagnosis of non-cancerous, lung adenocarcinoma (LAC), and lung squamous cell carcinoma (SCC) tissues from human. Our results show that the combination of second harmonic generation (SHG) and multiphoton excited autofluorescence (MAF) signals may be used to acquire morphological and quantitative information in discriminating cancerous from non-cancerous lung tissues. Specifically, non-cancerous lung tissues are largely fibrotic in structure while cancerous specimens are composed primarily of tumor masses. Quantitative ratiometric analysis using MAF to SHG index (MAFSI or SAAID) shows that the average MAFSI for noncancerous and LAC lung tissue pairs are 0.55 +/-0.23 and 0.87+/-0.15 respectively. In comparison, the MAFSIs for the noncancerous and SCC tissue pairs are 0.50+/-0.12 and 0.72+/-0.13 respectively. Intrinsic fluorescence ratio (FAD/NADH) of SCC and non-cancerous tissues are 0.40+/-0.05 and 0.53+/-0.05 respectively, the redox ratio of SCC diminishes significantly, indicating that increased cellular metabolic activity. Our study shows that nonlinear optical microscopy can assist in differentiating and diagnosing pulmonary cancer from non-cancerous tissues. With additional development, multiphoton microscopy may be used for the clinical diagnosis of lung cancers.

  4. Multiphoton ionization of uranium hexafluoride

    SciTech Connect

    Armstrong, D.P.; Harkins, D.A. ); Compton, R.N.; Ding, D. )

    1994-01-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy (TOFMS) and photoelectron spectroscopy (PES) studies of UF[sub 6] are reported using focused light from the Nd:YAG laser fundamental ([lambda]=1064 nm) and its harmonics ([lambda]=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF[sup +][sub [ital x

  5. Spread of cochlear excitation during stimulation with pulsed infrared radiation: inferior colliculus measurements

    NASA Astrophysics Data System (ADS)

    Richter, C.-P.; Rajguru, S. M.; Matic, A. I.; Moreno, E. L.; Fishman, A. J.; Robinson, A. M.; Suh, E.; Walsh, J. T., Jr.

    2011-10-01

    Infrared neural stimulation (INS) has received considerable attention over the last few years. It provides an alternative method to artificially stimulate neurons without electrical current or the introduction of exogenous chromophores. One of the primary benefits of INS could be the improved spatial selectivity when compared with electrical stimulation. In the present study, we have evaluated the spatial selectivity of INS in the acutely damaged cochlea of guinea pigs and compared it to stimulation with acoustic tone pips in normal-hearing animals. The radiation was delivered via a 200 µm diameter optical fiber, which was inserted through a cochleostomy into the scala tympani of the basal cochlear turn. The stimulated section along the cochlear spiral ganglion was estimated from the neural responses recorded from the central nucleus of the inferior colliculus (ICC). ICC responses were recorded in response to cochlear INS using a multichannel penetrating electrode array. Spatial tuning curves (STCs) were constructed from the responses. For INS, approximately 55% of the activation profiles showed a single maximum, ~22% had two maxima and ~13% had multiple maxima. The remaining 10% of the profiles occurred at the limits of the electrode array and could not be classified. The majority of ICC STCs indicated that the spread of activation evoked by optical stimuli is comparable to that produced by acoustic tone pips.

  6. Plasma membrane nanoporation as a possible mechanism behind infrared excitation of cells

    NASA Astrophysics Data System (ADS)

    Beier, Hope T.; Tolstykh, Gleb P.; Musick, Joshua D.; Thomas, Robert J.; Ibey, Bennett L.

    2014-12-01

    Objective. Short infrared (IR) laser pulses have been used to stimulate action potentials in neurons both in vivo and in vitro. However, the mechanism(s) underlying this phenomenon has remained elusive. In vitro studies have found that pulsed IR exposure generates a nearly instant change in capacitance in the plasma membrane, characterized by inward rectification, a common feature in pore-forming exposures, such as electrical pulses and acoustic shock waves. Based on this similarity, we hypothesize that the mechanism of IR stimulation is the formation of short-lived nanopores in the plasma membrane. These transient, small-diameter pores allow the influx of extracellular ions that lead to action potential generation, possibly through activation of secondary messenger pathways or depolarization of the cell membrane resulting in activation of voltage-gated ion channels. Approach. A variety of fluorescent markers are used to observe the cell response to IR stimulation to monitor for effects indicative of nanoporation in other modalities. Main results. We observe rapid, transient rises in intracellular Ca2+, influx of YO-PRO-1 and propidium iodide into the cell signifying membrane permeabilization, cellular blebbing and swelling, and activation of the intracellular phosphoinositides lipid signaling pathway. Significance. This conclusion better explains the experimental observations and limitations of IR-induced neurological stimulation and represents a distinct theoretical shift in the understanding of the mechanism of IR-induced stimulation.

  7. Near-infrared-excited confocal Raman spectroscopy advances in vivo diagnosis of cervical precancer

    NASA Astrophysics Data System (ADS)

    Duraipandian, Shiyamala; Zheng, Wei; Ng, Joseph; Low, Jeffrey J. H.; Ilancheran, Arunachalam; Huang, Zhiwei

    2013-06-01

    Raman spectroscopy is a unique optical technique that can probe the changes of vibrational modes of biomolecules associated with tissue premalignant transformation. This study evaluates the clinical utility of confocal Raman spectroscopy over near-infrared (NIR) autofluorescence (AF) spectroscopy and composite NIR AF/Raman spectroscopy for improving early diagnosis of cervical precancer in vivo at colposcopy. A rapid NIR Raman system coupled with a ball-lens fiber-optic confocal Raman probe was utilized for in vivo NIR AF/Raman spectral measurements of the cervix. A total of 1240 in vivo Raman spectra [normal (n=993), dysplasia (n=247)] were acquired from 84 cervical patients. Principal components analysis (PCA) and linear discriminant analysis (LDA) together with a leave-one-patient-out, cross-validation method were used to extract the diagnostic information associated with distinctive spectroscopic modalities. The diagnostic ability of confocal Raman spectroscopy was evaluated using the PCA-LDA model developed from the significant principal components (PCs) [i.e., PC4, 0.0023% PC5, 0.00095% PC8, 0.00022%, (p<0.05)], representing the primary tissue Raman features (e.g., 854, 937, 1095, 1253, 1311, 1445, and 1654 cm-1). Confocal Raman spectroscopy coupled with PCA-LDA modeling yielded the diagnostic accuracy of 84.1% (a sensitivity of 81.0% and a specificity of 87.1%) for in vivo discrimination of dysplastic cervix. The receiver operating characteristic curves further confirmed that the best classification was achieved using confocal Raman spectroscopy compared to the composite NIR AF/Raman spectroscopy or NIR AF spectroscopy alone. This study illustrates that confocal Raman spectroscopy has great potential to improve early diagnosis of cervical precancer in vivo during clinical colposcopy.

  8. Autofluorescence Imaging With Near-Infrared Excitation:Normalization by Reflectance to Reduce Signal From Choroidal Fluorophores

    PubMed Central

    Cideciyan, Artur V.; Swider, Malgorzata; Jacobson, Samuel G.

    2015-01-01

    Purpose. We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. Methods. Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. Results. Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizing NIR-RAFI reduced the choroidal component of the signal in regions of atrophy. Quantitative evaluation of RPE atrophy area showed no significant differences between SW-RAFI and normalized NIR-RAFI. Conclusions. Imaging of RPE atrophy using lipofuscin-based AF imaging has become the gold standard. However, this technique involves bright SW lights that are uncomfortable and may accelerate the rate of disease progression in vulnerable retinas. The NIR-RAFI method developed here is a melanin-based alternative that is not absorbed by opsins and bisretinoid moieties, and is comfortable to view. Further development of this method may result in a nonmydriatic and comfortable imaging method to quantify RPE atrophy extent and its expansion rate. PMID:26024124

  9. Resonance-enhanced multiphoton ionization spectra of jet-cooled methanol and ethanol

    NASA Astrophysics Data System (ADS)

    Philis, John G.

    2007-12-01

    The first spectroscopic study of the 3p ? nO multiphoton excitation of jet-cooled methanol and ethanol is presented. The mass-resolved resonance-enhanced multiphoton ionization (REMPI) spectra of CH 3OH and CD 3OD are compared to the VUV absorption spectra. The 2 + 1 REMPI spectra of CH 3CH 2OH and CH 3CH 2OD have a well-resolved vibrational structure and are attribute to trans ethanol. The production of the methyl radical (from methanol and ethanol) is revealed by its 3pz2A2??XA2?2+1 REMPI spectrum.

  10. Line broadening in multiphoton processes with a resonant intermediate transition

    NASA Technical Reports Server (NTRS)

    Wang, C. C.; James, J. V.; Xia, J.-F.

    1983-01-01

    It is found that the line width of the excitation spectrum for multiphoton ionization is broadened much more severely than the cascade fluorescence originating from the resonant intermediate level. These results derive from the mutual effects of the ionizing and resonating transitions, which are not properly accounted for in perturbative treatments. In general, the ionization line shape can be expressed as the sum of two Lorentzian components, each with different degrees of broadening. This line shape reduces to that of the resonating transition in the limit of vanishing intensities. Moreover, the fluorescence line shape may also exhibit a second component whose amplitude may become important under certain conditions.

  11. Multi-photon photoelectron spectromicroscopy of supported polystyrene spheres

    NASA Astrophysics Data System (ADS)

    Lilienkamp, Gerhard; Lindla, Florian; Senft, Christoph; Daum, Winfried

    2008-08-01

    Multi-photon photoemission excited by 100 fs, 400 nm laser pulses leads to an unexpected high contrast in photoelectron images of polystyrene spheres on a platinum substrate. The total, energy-integrated photoelectron yield shows clear signatures of two-photon photoemission from the substrate while photoemission from polystyrene is dominated by one-photon processes for low laser power and multi-photon processes for higher laser power. For excitation with UV light from a conventional Hg arc lamp, we observe a marked energy shift of the photoelectron spectrum of polystyrene with respect to that of the substrate. This shift is related to the different surface potentials of the conductive substrate and the dielectric spheres in the strong electric field of the objective lens of the microscope. Laser illumination causes photoconductivity in polystyrene by efficient two-photon excitation of long-lived states and induces a shifting of the surface potential of the polystyrene spheres. Pump-probe experiments support our conclusion that photoemission from polystyrene takes place from these long-lived intermediate states via a one-photon process for sufficiently low laser power. We suggest that photoelectron spectromicroscopy might be useful as a non-scanning method for fast height profiling of supported dielectric structures.

  12. Three-dimensional tooth imaging using multiphoton and second harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Min-Huey; Chen, Wei-Liang; Sun, Yen; Fwu, Peter Tramyeon; Lin, Ming-Gu; Dong, Chen-Yuan

    2007-02-01

    Detailed morphological and cellular information relating to the human tooth have traditionally been obtained through histological studies that required decalcification, staining, and fixation. With the recent invention of multiphoton microscopy, it has become possible to acquire high resolution images without histological procedures. Using an epiilluminated multiphoton microscope, we obtained two-photon excited autofluorescence and second harmonic generation (SHG) images of ex vivo human tooth. By combining these two imaging modalities we obtained submicron resolution images of the enamel, dentin, and the periodontal ligaments. The enamel emits endogenous two-photon autofluorescence. The structure of the dentin is visible from both the autofluorescence and second harmonic generation signals. The periodontal ligament composed mostly of collagen can be visualized by SHG imaging. We also constructed three dimensional images of the enamel, dentin, and periodontal ligament. The effectiveness of using multiphoton and second harmonic generation microscopy to obtain structural information of teeth suggest its potential use in dental diagnostics.

  13. In Vivo Microscopy of the Mouse Brain Using Multiphoton Laser Scanning Techniques

    PubMed Central

    Yoder, Elizabeth J.

    2008-01-01

    The use of multiphoton microscopy for imaging mouse brain in vivo offers several advantages and poses several challenges. This tutorial begins by briefly comparing multiphoton microscopy with other imaging modalities used to visualize the brain and its activity. Next, an overview of the techniques for introducing fluorescence into whole animals to generate contrast for in vivo microscopy using two-photon excitation is presented. Two different schemes of surgically preparing mice for brain imaging with multiphoton microscopy are reviewed. Then, several issues and problems with in vivo microscopy - including motion artifact, respiratory and cardiac rhythms, maintenance of animal health, anesthesia, and the use of fiducial markers – are discussed. Finally, examples of how these techniques have been applied to visualize the cerebral vasculature and its response to hypercapnic stimulation are provided. PMID:20975841

  14. Application of Multiphoton Microscopy in Dermatological Studies: a Mini-Review

    PubMed Central

    Yew, Elijah; Rowlands, Christopher

    2014-01-01

    This review summarizes the historical and more recent developments of multiphoton microscopy, as applied to dermatology. Multiphoton microscopy offers several advantages over competing microscopy techniques: there is an inherent axial sectioning, penetration depths that compete well with confocal microscopy on account of the use of near-infrared light, and many two-photon contrast mechanisms, such as second-harmonic generation, have no analogue in one-photon microscopy. While the penetration depths of photons into tissue are typically limited on the order of hundreds of microns, this is of less concern in dermatology, as the skin is thin and readily accessible. As a result, multiphoton microscopy in dermatology has generated a great deal of interest, much of which is summarized here. The review covers the interaction of light and tissue, as well as the various considerations that must be made when designing an instrument. The state of multiphoton microscopy in imaging skin cancer and various other diseases is also discussed, along with the investigation of aging and regeneration phenomena, and finally, the use of multiphoton microscopy to analyze the transdermal transport of drugs, cosmetics and other agents is summarized. The review concludes with a look at potential future research directions, especially those that are necessary to push these techniques into widespread clinical acceptance. PMID:25075226

  15. Experimental demonstration of mode-selective phonon excitation of 6H-SiC by a mid-infrared laser with anti-Stokes Raman scattering spectroscopy

    SciTech Connect

    Yoshida, Kyohei; Hachiya, Kan; Okumura, Kensuke; Mishima, Kenta; Inukai, Motoharu; Torgasin, Konstantin; Omer, Mohamed; Sonobe, Taro; Zen, Heishun; Negm, Hani; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki

    2013-10-28

    Mode-selective phonon excitation by a mid-infrared laser (MIR-FEL) is demonstrated via anti-Stokes Raman scattering measurements of 6H-silicon carbide (SiC). Irradiation of SiC with MIR-FEL and a Nd-YAG laser at 14 K produced a peak where the Raman shift corresponds to a photon energy of 119 meV (10.4 ?m). This phenomenon is induced by mode-selective phonon excitation through the irradiation of MIR-FEL, whose photon energy corresponds to the photon-absorption of a particular phonon mode.

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

    NASA Astrophysics Data System (ADS)

    Skala, Melissa Caroline

    2007-12-01

    Cancer morbidity and mortality is greatly reduced when the disease is diagnosed and treated early in its development. Tissue biopsies are the gold standard for cancer diagnosis, and an accurate diagnosis requires a biopsy from the malignant portion of an organ. Light, guided through a fiber optic probe, could be used to inspect regions of interest and provide real-time feedback to determine the optimal tissue site for biopsy. This approach could increase the diagnostic accuracy of current biopsy procedures. The studies in this thesis have characterized changes in tissue optical signals with carcinogenesis, increasing our understanding of the sensitivity of optical techniques for cancer detection. All in vivo studies were conducted on the dimethylbenz[alpha]anthracene treated hamster cheek pouch model of epithelial carcinogenesis. Multiphoton microscopy studies in the near infrared wavelength region quantified changes in tissue morphology and fluorescence with carcinogenesis in vivo. Statistically significant morphological changes with precancer included increased epithelial thickness, loss of stratification in the epithelium, and increased nuclear diameter. Fluorescence changes included a statistically significant decrease in the epithelial fluorescence intensity per voxel at 780 nm excitation, a decrease in the fluorescence lifetime of protein-bound nicotinamide adenine dinucleotide (NADH, an electron donor in oxidative phosphorylation), and an increase in the fluorescence lifetime of protein-bound flavin adenine dinucleotide (FAD, an electron acceptor in oxidative phosphorylation) with precancer. The redox ratio (fluorescence intensity of FAD/NADH, a measure of the cellular oxidation-reduction state) did not significantly change with precancer. Cell culture experiments (MCF10A cells) indicated that the decrease in protein-bound NADH with precancer could be due to increased levels of glycolysis. Point measurements of diffuse reflectance and fluorescence spectra in 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.

  17. Infrared study on room-temperature atomic layer deposition of HfO{sub 2} using tetrakis(ethylmethylamino)hafnium and remote plasma-excited oxidizing agents

    SciTech Connect

    Kanomata, Kensaku; Ohba, Hisashi; Pungboon Pansila, P.; Ahmmad, Bashir; Kubota, Shigeru; Hirahara, Kazuhiro; Hirose, Fumihiko

    2015-01-01

    Room-temperature atomic layer deposition (ALD) of HfO{sub 2} was examined using tetrakis (ethylmethylamino)hafnium (TEMAH) and remote plasma-excited water and oxygen. A growth rate of 0.26?nm/cycle at room temperature was achieved, and the TEMAH adsorption and its oxidization on HfO{sub 2} were investigated by multiple internal reflection infrared absorption spectroscopy. It was observed that saturated adsorption of TEMAH occurs at exposures of ?1?×?10{sup 5}?L (1 L?=?1?×?10{sup ?6} Torr s) at room temperature, and the use of remote plasma-excited water and oxygen vapor is effective in oxidizing the TEMAH molecules on the HfO{sub 2} surface, to produce OH sites. The infrared study suggested that Hf–OH plays a role as an adsorption site for TEMAH. The reaction mechanism of room temperature HfO{sub 2} ALD is discussed in this paper.

  18. The multiphoton ionization of uranium hexafluoride

    SciTech Connect

    Armstrong, D.P. . UEO Enrichment Technical Operations Div.)

    1992-05-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF{sub 6} have been conducted using focused light from the Nd:YAG laser fundamental ({lambda}=1064 nm) and its harmonics ({lambda}=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF{sub x}{sup +} fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U{sup n+} ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U{sup 2+}) intensity is much greater than that of the singly-charged uranium ion (U{sup +}). For the case of the tunable dye laser experiments, the U{sup n+} (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U{sup 2+} ion and the absence or very small intensities of UF{sub x}{sup +} fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule.

  19. Cell-based and in vivo spectral analysis of fluorescent proteins for multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Salomonnson, Emma; Mihalko, Laura Anne; Verkhusha, Vladislav V.; Luker, Kathryn E.; Luker, Gary D.

    2012-09-01

    Multiphoton microscopy of cells and subcellular structures labeled with fluorescent proteins is the state-of-the-art technology for longitudinal imaging studies in tissues and living animals. Successful analysis of separate cell populations or signaling events by intravital microscopy requires optimal pairing of multiphoton excitation wavelengths with spectrally distinct fluorescent proteins. While prior studies have analyzed two photon absorption properties of isolated fluorescent proteins, there is limited information about two photon excitation and fluorescence emission profiles of fluorescent proteins expressed in living cells and intact tissues. Multiphoton microscopy was used to analyze fluorescence outputs of multiple blue, green, and red fluorescent proteins in cultured cells and orthotopic tumor xenografts of human breast cancer cells. It is shown that commonly used orange and red fluorescent proteins are excited efficiently by 750 to 760 nm laser light in living cells, enabling dual color imaging studies with blue or cyan proteins without changing excitation wavelength. It is also shown that small incremental changes in excitation wavelength significantly affect emission intensities from fluorescent proteins, which can be used to optimize multi-color imaging using a single laser wavelength. These data will direct optimal selection of fluorescent proteins for multispectral two photon microscopy.

  20. Resonant enhanced multiphoton ionization studies of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Dixit, S. N.; Levin, D.; Mckoy, V.

    1987-01-01

    In resonant enhanced multiphoton ionization (REMPI), an atom absorbs several photons making a transition to a resonant intermediate state and subsequently ionizing out of it. With currently available tunable narrow-band lasers, the extreme sensitivity of REMPI to the specific arrangement of levels can be used to selectively probe minute amounts of a single species (atom) in a host of background material. Determination of the number density of atoms from the observed REMPI signal requires a knowledge of the multiphoton ionization cross sections. The REMPI of atomic oxygen was investigated through various excitation schemes that are feasible with available light sources. Using quantum defect theory (QDT) to estimate the various atomic parameters, the REMPI dynamics in atomic oxygen were studied incorporating the effects of saturation and a.c. Stark shifts. Results are presented for REMPI probabilities for excitation through various 2p(3) (4S sup o) np(3)P and 2p(3) (4S sup o) nf(3)F levels.

  1. Origin of near to middle infrared luminescence and energy transfer process of Er3+/Yb3+co-doped fluorotellurite glasses under different excitations

    NASA Astrophysics Data System (ADS)

    Huang, Feifei; Liu, Xueqiang; Ma, Yaoyao; Kang, Shuai; Hu, Lili; Chen, Danping

    2015-02-01

    We report the near to middle infrared luminescence and energy transfer process of Er3+/Yb3+ co-doped fluorotellurite glasses under 980, 1550 and 800 nm excitations, respectively. Using a 980 nm laser diode pump, enhanced 1.5 and 2.7 ?m emissions from Er3+:I13/2-->4I15/2 and I11/2-->4I13/2 transitions are observed, in which Yb3+ ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb3+ can also be used as an acceptor and intensive upconversion luminescence of around 1000 nm is achieved from Er3+:I11/2-->4I15/2 and Yb3+: F5/2-->4F7/2 transitions using 1550 nm excitation. In addition, the luminescence properties and variation trendency by 800 nm excitation is similar to that using 1550 nm excitation. The optimum Er3+ and Yb3+ ion ratio is 1:1.5 and excess Yb3+ ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er3+/Yb3+ co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells.

  2. Highly-reproducible Raman scattering of NaYF4:Yb,Er@SiO2@Ag for methylamphetamine detection under near-infrared laser excitation.

    PubMed

    Ma, Yongmei; Liu, Honglin; Han, Zhenzhen; Yang, Liangbao; Liu, Jinhuai

    2015-08-01

    This study reported the significantly improved Raman enhancement ability of silver nanoparticles (Ag NPs) by decorating them on single NaYF4:Yb,Er@SiO2 core-shell particles (UC@SiO2@Ag) under a 785 nm excitation. The optimal thickness of the silica shell can be easily obtained by adjusting the amounts of TEOS, which is the crucial element to balance the upconversion and the formation of a hot spot by Ag NP aggregation. This substrate revealed highly reproducible properties, which is crucial to the practical application of SERS technology. This substrate exhibited an excellent sensitivity for methylamphetamine detection under near-infrared excitation. The advantages of NIR excitation in our SERS sensing open up a new application field of UC-noble metal composites, and also promise a new research direction for the synthesis and applications of SERS-active nanostructures. PMID:26090604

  3. Multiphoton cryo microscope with sample temperature control

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; Uchugonova, A.; König, K.

    2013-02-01

    We present a multiphoton microscope system which combines the advantages of multiphoton imaging with precise control of the sample temperature. The microscope provides online insight in temperature-induced changes and effects in plant tissue and animal cells with subcellular resolution during cooling and thawing processes. Image contrast is based on multiphoton fluorescence intensity or fluorescence lifetime in the range from liquid nitrogen temperature up to +600°C. In addition, micro spectra from the imaged regions can be recorded. We present measurement results from plant leaf samples as well as Chinese hamster ovary cells.

  4. Multiphoton Quantum Optics and Quantum State Engineering

    E-print Network

    Dell'Anno, F; Illuminati, F; 10.1016/j.physrep.2006.01.004

    2009-01-01

    We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states...

  5. Promising new wavelengths for multi-photon microscopy: thinking outside the Ti:Sapphire box

    NASA Astrophysics Data System (ADS)

    Norris, Greg; Amor, Rumelo; Dempster, John; Amos, William B.; McConnell, Gail

    2013-02-01

    Multi-photon excitation (MPE) imaging is dominated by the Ti:Sapphire laser as the source for excitation. However, it is limited when considering 3PE of common fluorophores and efficient 2PE of UV dyes which require wavelengths beyond the range of the Ti:Sapphire. Two ultra-short pulsed sources are presented as alternatives: a novel optical parametric oscillator (OPO) geometry (1400-1600nm) and the sum-frequency mixing of an OPO and Yb-doped fibre laser, providing a tunable output (626-635nm). For long wavelengths, we report three-photon laser scanning microscopy (3PLSM) using a bi-directional pumped optical parametric oscillator (OPO) with signal wavelength output at 1500 nm. This novel laser was used to overcome the high optical loss in the infrared spectral region observed in laser scanning microscopes and objective lenses that renders them otherwise difficult to use for imaging. To test our system, we performed 3PLSM auto-fluorescence imaging of live plant cells at 1500 nm, specifically Spirogyra, and compared performance with two-photon excitation (2PLSM) imaging using a femtosecond pulsed Ti:Sapphire laser at 780 nm. Analysis of cell viability based on cytoplasmic organelle streaming and structural changes of cells revealed that at similar peak powers, 2PLSM caused gross cell damage after 5 minutes but 3PLSM showed little or no interference with cell function after 15 minutes. The 1500 nm OPO was thus shown to be a practical laser source for live cell imaging. For short wavelengths, we report the use of an all-solid-state ultra-short pulsed source specifically for two-photon microscopy at wavelengths shorter than those of the conventional Ti:Sapphire laser. Our approach involved sumfrequency mixing of the output from the long-wavelength OPO described above with residual pump radiation to generate fs-pulsed output in the red spectral region. We demonstrated the performance of our ultra-short pulsed system using fluorescently labelled and autofluorescent tissue, and compared with conventional Ti:Sapphire excitation. We observed a more than 3-fold increase in fluorescence signal intensity using our visible laser source in comparison with the Ti:Sapphire laser for two-photon excitation at equal illumination powers of 22 mW or less.

  6. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    SciTech Connect

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi-photon transitions are needed to help guide the experimental material selection. This report provides the theoretical basis for leading knowledgeable researchers along the path to develop multi-photon phosphor systems. The ultimate goal, a doubling of fluorescent lamp efficacy, is not going to be easily obtained. This report begins the process and should be followed with detailed experimental and theoretical research to continue the development process.

  7. How periodic orbit bifurcations drive multiphoton ionization

    E-print Network

    S. Huang; C. Chandre; T. Uzer

    2006-12-26

    The multiphoton ionization of hydrogen by a strong bichromatic microwave field is a complex process prototypical for atomic control research. Periodic orbit analysis captures this complexity: Through the stability of periodic orbits we can match qualitatively the variation of experimental ionization rates with a control parameter, the relative phase between the two modes of the field. Moreover, an empirical formula reproduces quantum simulations to a high degree of accuracy. This quantitative agreement shows how short periodic orbits organize the dynamics in multiphoton ionization.

  8. Multiphoton microscopy in brain imaging

    NASA Astrophysics Data System (ADS)

    Allegra Mascaro, A. L.; Silvestri, L.; Costantini, I.; Sacconi, L.; Maco, B.; Knott, G. W.; Pavone, F. S.

    2015-03-01

    Brain imaging is becoming an important field in the frame of the neurophotonics in correlations with other medical ones in neuroscience studying functional and morphological aspects. In this presentation an overview on multi photon imaging of the brain will be presented, together with innovative aspects related to big area imaging and correlative microscopy approaches. Multiphoton imaging applications will be described together with methods to improve the penetration depth and obtain large area detection, or correlating functional aspects in vivo on single neuron with large area, even on whole brain, morphological aspects. Connecting super resolution features at the nanometer level with micro, meso and macroscopic architectures is in fact one of the challenging aspects to understand brain functioning.

  9. 355 nm Multiphoton Dissociation and Ionization of 2, 5-Dihydroxyacetophenone

    NASA Astrophysics Data System (ADS)

    Dyakov, Yuri A.; Tsai, Shang-Ting; Bagchi, Arnab; Tseng, Chien-Ming; Lee, Yuan T.; Ni, Chi-Kung

    2009-09-01

    Multiphoton dissociation and ionization of 2,5-dihydroxyacetophenone (DHAP), an important matrix compound in UV matrix-assisted laser desorption/ionization (MALDI), is studied in a molecular beam at 355 nm using multimass ion imaging mass spectrometer and time-of-flight mass spectrometry. For laser fluence larger than 130 mJ/cm2, nearly all of the irradiated molecules absorb at least one photon. The absorption cross section was found to be ? = 1.3(±0.2) × 10-17cm2. Molecules excited by two photons quickly dissociate into fragments. The major channels are (1) C6H3(OH)2COCH3 ? C6H3(OH)2CO + CH3 and (2) C6H3(OH)2COCH3 ? C6H3(OH)2 + COCH3. Molecules absorbing three or more photons become parent ions or crack into smaller ionic fragments. The concentration ratio of ions (parent ions and ionic fragments) to neutral fragments is about 10-6:1. Changing the molecular beam carrier gas from He at 250 Torr to Ar at 300 Torr results in molecular beam clustering (dimers and trimers). Multiphoton ionization of clusters by a 355 nm laser beam produces only dimer cations, (C6H3(OH)2COCH3)2+. Protonated clusters or negatively charged ions, observed from a solid sample of DHAP using 355 nm multiphoton ionization, were not found in the molecular beam. The experimental results indicate that the photoionization occurs in the gas phase after DHAP vaporizes from the solid phase may not play an important role in the MALDI process.

  10. Infrared vibrational spectroscopy of [Ru(bpy)2(bpm)]2+ and [Ru(bpy)3]2+ in the excited triplet state.

    PubMed

    Mukuta, Tatsuhiko; Fukazawa, Naoto; Murata, Kei; Inagaki, Akiko; Akita, Munetaka; Tanaka, Sei'ichi; Koshihara, Shin-ya; Onda, Ken

    2014-03-01

    This work involved a detailed investigation into the infrared vibrational spectra of ruthenium polypyridyl complexes, specifically heteroleptic [Ru(bpy)2(bpm)](2+) (bpy = 2,2'-bipyridine and bpm = 2,2'-bipyrimidine) and homoleptic [Ru(bpy)3](2+), in the excited triplet state. Transient spectra were acquired 500 ps after photoexcitation, corresponding to the vibrational ground state of the excited triplet state, using time-resolved infrared spectroscopy. We assigned the observed bands to specific ligands in [Ru(bpy)2(bpm)](2+) based on the results of deuterium substitution and identified the corresponding normal vibrational modes using quantum-chemical calculations. Through this process, the more complex vibrational bands of [Ru(bpy)3](2+) were assigned to normal vibrational modes. The results are in good agreement with the model in which excited electrons are localized on a single ligand. We also found that the vibrational bands of both complexes associated with the ligands on which electrons are little localized appear at approximately 1317 and 1608 cm(-1). These assignments should allow the study of the reaction dynamics of various photofunctional systems including ruthenium polypyridyl complexes. PMID:24528148

  11. Multimodal microscopy and the stepwise multi-photon activation fluorescence of melanin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua

    The author's work is divided into three aspects: multimodal microscopy, stepwise multi-photon activation fluorescence (SMPAF) of melanin, and customized-profile lenses (CPL) for on-axis laser scanners, which will be introduced respectively. A multimodal microscope provides the ability to image samples with multiple modalities on the same stage, which incorporates the benefits of all modalities. The multimodal microscopes developed in this dissertation are the Keck 3D fusion multimodal microscope 2.0 (3DFM 2.0), upgraded from the old 3DFM with improved performance and flexibility, and the multimodal microscope for targeting small particles (the "Target" system). The control systems developed for both microscopes are low-cost and easy-to-build, with all components off-the-shelf. The control system have not only significantly decreased the complexity and size of the microscope, but also increased the pixel resolution and flexibility. The SMPAF of melanin, activated by a continuous-wave (CW) mode near-infrared (NIR) laser, has potential applications for a low-cost and reliable method of detecting melanin. The photophysics of melanin SMPAF has been studied by theoretical analysis of the excitation process and investigation of the spectra, activation threshold, and photon number absorption of melanin SMPAF. SMPAF images of melanin in mouse hair and skin, mouse melanoma, and human black and white hairs are compared with images taken by conventional multi-photon fluorescence microscopy (MPFM) and confocal reflectance microscopy (CRM). SMPAF images significantly increase specificity and demonstrate the potential to increase sensitivity for melanin detection compared to MPFM images and CRM images. Employing melanin SMPAF imaging to detect melanin inside human skin in vivo has been demonstrated, which proves the effectiveness of melanin detection using SMPAF for medical purposes. Selective melanin ablation with micrometer resolution has been presented using the Target system. Compared to the traditional selective photothermolysis, this method demonstrates higher precision, higher specificity and deeper penetration. Therefore, the SMPAF guided selective ablation of melanin is a promising tool of removing melanin for both medical and cosmetic purposes. Three CPLs have been designed for low-cost linear-motion scanners, low-cost fast spinning scanners and high-precision fast spinning scanners. Each design has been tailored to the industrial manufacturing ability and market demands.

  12. DNA Multiphoton Absorption Generates Localized Damage for Studying Repair Dynamics in Live Cells

    PubMed Central

    Daddysman, Matthew K.; Fecko, Christopher J.

    2011-01-01

    Investigations into the spatiotemporal dynamics of DNA repair using live-cell imaging are aided by the ability to generate well defined regions of ultravioletlike photolesions in an optical microscope. We demonstrate that multiphoton excitation of DNA in live cells with visible femtosecond pulses produces thymine cyclopyrimidine dimers (CPDs), the primary ultraviolet DNA photoproduct. The CPDs are produced with a cubic to supercubic power dependence using pulses in the wavelength range from at least 400 to 525 nm. We show that the CPDs are confined in all three spatial dimensions, making multiphoton excitation of DNA with visible light an ideal technique for generating localized DNA photolesions in a wide variety of samples, from cultured cells to thicker tissues. We demonstrate the utility of this method by applying it to investigate the spatiotemporal recruitment of GFP-tagged topoisomerase I (TopI) to sites of localized DNA damage in polytene chromosomes within live cells of optically thick Drosophila salivary glands. PMID:22067170

  13. Multiphoton Rabi oscillations of a ringlike three-level system

    NASA Astrophysics Data System (ADS)

    He, Yong Lin; Han, Jiu Ning

    2012-04-01

    We propose a ringlike three-level model and show that it can be realized using Stark states of highly excited potassium interacting with two-mode microwave fields. We demonstrate this by using both analytical model and numerical simulations to study the problems of multiphoton Rabi oscillations. The results show that the Rabi oscillation patterns of the ringlike three-level system exhibit additional envelope and nodes compared to the oscillatory behavior of a three-level cascade system; in other words, there exist collapse and revival phenomena for Rabi oscillation patterns. The origin of the collapse and revival of the population oscillations is the multiphoton two-color resonances at frequency ?=n?1+m?2. Our analytic results are in good agreement with numerical simulations. In addition, all the analytical solutions for the three basic configurations of the three-level system classified as the ?, vee, and cascade systems can be deduced from our analytical solution for the ringlike three-level configuration by setting one of the three coupling strengths equal to 0.

  14. Resonantly enhanced vacuum-ultraviolet generation and multiphoton ionization in carbon monoxide gas

    SciTech Connect

    Glownia, J.H.; Sander, R.K.

    1982-01-01

    Competition between three-photon resonantly enhanced vacuum ultraviolet third-harmonic generation and six-photon multiphoton ionization using the A state in gaseous carbon monoxide is observed. Excitation spectra of the third-harmonic emission exhibit increasing blue shifts and broadening with increasing pressure due to the phase matching requirements. Estimates for the efficiency and tunability show that third-harmonic generation in carbon monoxide molecules is a promising source for coherent vacuum ultraviolet light.

  15. Infrared phonon anomaly and magnetic excitations in single-crystal Cu3Bi(SeO3)2O2Cl

    NASA Astrophysics Data System (ADS)

    Miller, Kevin H.; Martin, C.; Xi, X.; Berger, H.; Carr, G. L.; Tanner, D. B.

    2012-02-01

    Infrared reflection as a function of temperature has been measured on the anisotropic single-crystal Cu3Bi(SeO3)2O2Cl. The complex dielectric function and optical properties along all three crystal axes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Below 110 K drastic anomalies in the phonon spectrum (e.g., new modes and splitting of existing modes) are observed along all three crystal axes. Transmission in the terahertz region as a function of temperature has revealed magnetic excitations originating below the ferromagnetic ordering temperature, Tc=24 K. The origin of the excitations in the magnetic state will be discussed in terms of their polarization and externally-applied magnetic field dependence.

  16. Resonance Enhanced Multi-photon Spectroscopy of DNA

    NASA Astrophysics Data System (ADS)

    Ligare, Marshall Robert

    For over 50 years DNA has been studied to better understand its connection to life and evolution. These past experiments have led to our understanding of its structure and function in the biological environment but the interaction of DNA with UV radiation at the molecular level is still not very well understood. Unique mechanisms in nucleobase chromaphores protect us from adverse chemical reactions after UV absorption. Studying these processes can help develop theories for prebiotic chemistry and the possibility of alternative forms of DNA. Using resonance enhanced multi-photon spectroscopic techniques in the gas phase allow for the structure and dynamics of individual nucleobases to be studied in detail. Experiments studying different levels of structure/complexity with relation to their biological function are presented. Resonant IR multiphoton dissociation spectroscopy in conjunction with molecular mechanics and DFT calculations are used to determine gas phase structures of anionic nucleotide clusters. A comparison of the identified structures with known biological function shows how the hydrogen bonding of the nucleotides and their clusters free of solvent create favorable structures for quick incorporation into enzymes such as DNA polymerase. Resonance enhanced multi-photon ionization (REMPI) spectroscopy techniques such as resonant two photon ionization (R2PI) and IR-UV double resonance are used to further elucidate the structure and excited state dynamics of the bare nucleobases thymine and uracil. Both exhibit long lived excited electronic states that have been implicated in DNA photolesions which can ultimately lead to melanoma and carcinoma. Our experimental data in comparison with many quantum chemical calculations suggest a new picture for the dynamics of thymine and uracil in the gas phase. A high probability of UV absorption from a vibrationally hot ground state to the excited electronic state shows that the stability of thymine and uracil comes from its intrinsic molecular properties and possibly a hydrogen bonding solvent capable of dissipating excess vibrational energy. Due to the high specificity and sensitivity of resonant two photon ionization coupled with molecular beam mass spectrometry a new analytical technique for identifying molecular markers in archaeological vessels is presented. The xanthine alkaloids theobromine, theophylline and caffeine are identified in Central American and North American pottery sherds by direct desorption/resonant laser ionization mass spectrometry.

  17. Coherent multi-photon interference and compensation of polarization dispersion

    E-print Network

    Fini, John Michael

    2001-01-01

    This thesis will explore strategies for coherent manipulation of multi-photon packets. Correlated multi-photon states can arise in nonlinear optical devices. A nonlinear quantum interferometer which includes these states ...

  18. Multi-photon laser scanning microscopy using an acoustic optical deflector.

    PubMed Central

    Lechleiter, James D; Lin, Da-Ting; Sieneart, Ilse

    2002-01-01

    Multi-photon laser scanning microscopes have many advantages over single-photon systems. However, the speed and flexibility of currently available multi-photon microscopes are limited by the use of mechanical mirrors to steer pulsed radiation for fluorophore excitation. Here, we describe the multi-photon adaptation of a confocal microscope that uses an acoustic optical deflector (AOD) for beam steering. AODs are capable of very rapid scanning and, in addition, offer the flexibility of zooming, panning, and being adjustable for slow image acquisition. Because of the highly dispersive nature of AODs, pulsed radiation must be temporally compressed by introducing negative dispersion into the beam path. More critically, pulsed radiation must also be spatially compressed by introducing lateral dispersion into the beam path. This was accomplished by using two prisms in the external beam path and by introducing a third prism element subsequent to the AOD. The end result is an AOD-based multi-photon microscope that is capable of rapid imaging of physiological events as well as slow detection of weakly fluorescent biological samples. PMID:12324446

  19. Live-cell multiphoton fluorescence correlation spectroscopy with an improved large Stokes shift fluorescent protein

    PubMed Central

    Guan, Yinghua; Meurer, Matthias; Raghavan, Sarada; Rebane, Aleksander; Lindquist, Jake R.; Santos, Sofia; Kats, Ilia; Davidson, Michael W.; Mazitschek, Ralph; Hughes, Thomas E.; Drobizhev, Mikhail; Knop, Michael; Shah, Jagesh V.

    2015-01-01

    We report an improved variant of mKeima, a monomeric long Stokes shift red fluorescent protein, hmKeima8.5. The increased intracellular brightness and large Stokes shift (?180 nm) make it an excellent partner with teal fluorescent protein (mTFP1) for multiphoton, multicolor applications. Excitation of this pair by a single multiphoton excitation wavelength (MPE, 850 nm) yields well-separable emission peaks (?120-nm separation). Using this pair, we measure homo- and hetero-oligomerization interactions in living cells via multiphoton excitation fluorescence correlation spectroscopy (MPE-FCS). Using tandem dimer proteins and small-molecule inducible dimerization domains, we demonstrate robust and quantitative detection of intracellular protein–protein interactions. We also use MPE-FCCS to detect drug–protein interactions in the intracellular environment using a Coumarin 343 (C343)-conjugated drug and hmKeima8.5 as a fluorescence pair. The mTFP1/hmKeima8.5 and C343/hmKeima8.5 combinations, together with our calibration constructs, provide a practical and broadly applicable toolbox for the investigation of molecular interactions in the cytoplasm of living cells. PMID:25877871

  20. Label-free multi-photon imaging using a compact femtosecond fiber laser mode-locked by carbon nanotube saturable absorber

    PubMed Central

    Kieu, K.; Mehravar, S.; Gowda, R.; Norwood, R. A.; Peyghambarian, N.

    2013-01-01

    We demonstrate label-free multi-photon imaging of biological samples using a compact Er3+-doped femtosecond fiber laser mode-locked by a single-walled carbon nanotube (CNT). These compact and low cost lasers have been developed by various groups but they have not been exploited for multiphoton microscopy. Here, it is shown that various multiphoton imaging modalities (e.g. second harmonic generation (SHG), third harmonic generation (THG), two-photon excitation fluorescence (TPEF), and three-photon excitation fluorescence (3PEF)) can be effectively performed on various biological samples using a compact handheld CNT mode-locked femtosecond fiber laser operating in the telecommunication window near 1560nm. We also show for the first time that chlorophyll fluorescence in plant leaves and diatoms can be observed using 1560nm laser excitation via three-photon absorption. PMID:24156074

  1. Measurements of multiphoton action cross sections for multiphoton microscopy

    PubMed Central

    Cheng, Li-Chung; Horton, Nicholas G.; Wang, Ke; Chen, Shean-Jen; Xu, Chris

    2014-01-01

    We report quantitative measurements of two-, three-, and four-photon excitation action cross sections of several commonly used fluorophores and fluorescent proteins at three different excitation wavelengths of 800 nm, 1300 nm, and 1680 nm. The measured cross section values are consistent with simple quantum mechanic estimations. These values indicate that the optimum repetition rate for deep tissue 3-photon microscopy is approximately 1 to 2 MHz. We further demonstrate that it is feasible to perform 4-photon fluorescence microscopy of GFP labeled microglia in mouse brain in vivo at 1700 nm. 4-photon excitation increases the accessibility of fluorophores at the long wavelength spectral window of 1700 nm. PMID:25360361

  2. Diffraction can mimic saturation in multiphoton absorbers

    NASA Astrophysics Data System (ADS)

    Potasek, M.; Parilov, E.; Walker, M.

    2014-03-01

    Many traditional investigations of saturation in multiphoton absorbers with the z-scan method use an approximate analytical formula that assumes a steady-state approximation. Using a numerical simulation for Maxwell's equations for laser propagation including diffraction and coupled electron population dynamics, we show that the commonly used analytical formula for determining saturation in multiphoton absorbers is often incorrect, even when the sample thickness is only one diffraction length. Using published experimental data on an organic chromophore, we show that saturation, in fact, does not occur at the laser intensity values predicted for these two and three photon absorbers. We numerically fit the published experimental z-scan data and obtain new absorption coefficients for multiphoton absorbers that accurately reflect their intrinsic values. The new values are from three to ten times larger than the published values. Because multiphoton absorbers are being used more extensively in many applications such as optical limiter, medical diagnostics and two photon microscopy, it is important to have accurate values for the two and three-photon absorption coefficients. Knowing the real value of the multiphoton absorber coefficients, even for a single diffraction length, is therefore of the utmost importance. In particular, the laser intensity at which the absorber saturates can determine which absorber is useful for a particular application.

  3. Continuous-mode multi-photon filtering

    E-print Network

    Hongting Song; Guofeng Zhang; Zairong Xi

    2015-12-04

    The purpose of this paper is to derive filters for an arbitrary open quantum system driven by a light wavepacket prepared in a continuous-mode multi-photon state. A continuous-mode multi-photon state is a state of a travelling light wavepacket that contains a definite number of photons and is characterised by a temporal (or equivalently spectral) profile. After the interaction with the system, the outgoing light can be monitored by means of homodyne detection or photodetection. Filters for both measurement schemes are derived in this paper. Unlike the vacuum or the coherent state case, the annihilation operator of the light field acting on a multi-photon state changes the state by annihilating a photon, and this makes the traditional filtering techniques inapplicable. To circumvent this difficulty, we adopt a non-Markovian embedding technique proposed in \\cite{gough:2013} for the study of the single-photon filtering problem. However, the multi-photon nature of the problem addressed in this paper makes the study much more mathematically involved. Moreover, as demonstrated by an example --- a two-level system driven by a continuous-mode two-photon state, multi-photon filters can reveal interesting strong nonlinear optical phenomena absent in both the single-photon state case and the continuous-mode Fock state case.

  4. Multi-focal multiphoton lithography.

    PubMed

    Ritschdorff, Eric T; Nielson, Rex; Shear, Jason B

    2012-03-01

    Multiphoton lithography (MPL) provides unparalleled capabilities for creating high-resolution, three-dimensional (3D) materials from a broad spectrum of building blocks and with few limitations on geometry, qualities that have been key to the design of chemically, mechanically, and biologically functional microforms. Unfortunately, the reliance of MPL on laser scanning limits the speed at which fabrication can be performed, making it impractical in many instances to produce large-scale, high-resolution objects such as complex micromachines, 3D microfluidics, etc. Previously, others have demonstrated the possibility of using multiple laser foci to simultaneously perform MPL at numerous sites in parallel, but use of a stage-scanning system to specify fabrication coordinates resulted in the production of identical features at each focal position. As a more general solution to the bottleneck problem, we demonstrate here the feasibility for performing multi-focal MPL using a dynamic mask to differentially modulate foci, an approach that enables each fabrication site to create independent (uncorrelated) features within a larger, integrated microform. In this proof-of-concept study, two simultaneously scanned foci produced the expected two-fold decrease in fabrication time, and this approach could be readily extended to many scanning foci by using a more powerful laser. Finally, we show that use of multiple foci in MPL can be exploited to assign heterogeneous properties (such as differential swelling) to micromaterials at distinct positions within a fabrication zone. PMID:22282105

  5. Infrared phonon anomaly and magnetic excitations in single-crystal Cu3Bi(SeO3)2O2Cl

    NASA Astrophysics Data System (ADS)

    Miller, K. H.; Stephens, P. W.; Martin, C.; Constable, E.; Lewis, R. A.; Berger, H.; Carr, G. L.; Tanner, D. B.

    2012-11-01

    Infrared reflection and transmission as a function of temperature have been measured on single crystals of Cu3Bi(SeO3)2O2Cl. The complex dielectric function and optical properties along all three principal axes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Below 115 K, 16 additional modes [8(E?â)+6(E?b?)+2(E??)] appear in the phonon spectra; however, powder x-ray diffraction measurements do not detect a new structure at 85 K. Potential explanations for the new phonon modes are discussed. Transmission in the far infrared as a function of temperature has revealed magnetic excitations originating below the magnetic ordering temperature (Tc˜24 K). The origin of the excitations in the magnetically ordered state will be discussed in terms of their response to different polarizations of incident light, behavior in externally applied magnetic fields, and the anisotropic magnetic properties of Cu3Bi(SeO3)2O2Cl as determined by dc susceptibility measurements.

  6. Suitable microscope objectives for multiphoton digital imaging

    NASA Astrophysics Data System (ADS)

    Benham, Gerald S.; Schwartz, Stanley

    2002-06-01

    The proper choice of an objective lens can have a profound effect on multiphoton microscopy. Multiphoton requires that the objective have adequate transmission in the IR range. This technology has a requisite to image the specimen near the slide surface next to the cover glass and to of 200 microns or more. Fluor and Plan Apochromat objectives. All lenses suffer from aberrations, which can prevent imaging an exact replica of the object. Most objectives could be used for multiphoton imaging;; however lenses should be selected from Plan Fluors, Plan Apochromats, and Super (S) Fluors. Highly corrected water immersion objectives (WI) permit deep penetration within aqueous environments and living tissues, beyond that of oil immersion objectives. Spectral transmission data is presented for Nikon CFI60 various objective lenses with high Nas, long working distances, and maximum aberration correction.

  7. Multiphoton microscopy in defining liver function

    NASA Astrophysics Data System (ADS)

    Thorling, Camilla A.; Crawford, Darrell; Burczynski, Frank J.; Liu, Xin; Liau, Ian; Roberts, Michael S.

    2014-09-01

    Multiphoton microscopy is the preferred method when in vivo deep-tissue imaging is required. This review presents the application of multiphoton microscopy in defining liver function. In particular, multiphoton microscopy is useful in imaging intracellular events, such as mitochondrial depolarization and cellular metabolism in terms of NAD(P)H changes with fluorescence lifetime imaging microscopy. The morphology of hepatocytes can be visualized without exogenously administered fluorescent dyes by utilizing their autofluorescence and second harmonic generation signal of collagen, which is useful in diagnosing liver disease. More specific imaging, such as studying drug transport in normal and diseased livers are achievable, but require exogenously administered fluorescent dyes. If these techniques can be translated into clinical use to assess liver function, it would greatly improve early diagnosis of organ viability, fibrosis, and cancer.

  8. New developments in multimodal clinical multiphoton tomography

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2011-03-01

    80 years ago, the PhD student Maria Goeppert predicted in her thesis in Goettingen, Germany, two-photon effects. It took 30 years to prove her theory, and another three decades to realize the first two-photon microscope. With the beginning of this millennium, first clinical multiphoton tomographs started operation in research institutions, hospitals, and in the cosmetic industry. The multiphoton tomograph MPTflexTM with its miniaturized flexible scan head became the Prism-Award 2010 winner in the category Life Sciences. Multiphoton tomographs with its superior submicron spatial resolution can be upgraded to 5D imaging tools by adding spectral time-correlated single photon counting units. Furthermore, multimodal hybrid tomographs provide chemical fingerprinting and fast wide-field imaging. The world's first clinical CARS studies have been performed with a hybrid multimodal multiphoton tomograph in spring 2010. In particular, nonfluorescent lipids and water as well as mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen have been imaged in patients with dermatological disorders. Further multimodal approaches include the combination of multiphoton tomographs with low-resolution imaging tools such as ultrasound, optoacoustic, OCT, and dermoscopy systems. Multiphoton tomographs are currently employed in Australia, Japan, the US, and in several European countries for early diagnosis of skin cancer (malignant melanoma), optimization of treatment strategies (wound healing, dermatitis), and cosmetic research including long-term biosafety tests of ZnO sunscreen nanoparticles and the measurement of the stimulated biosynthesis of collagen by anti-ageing products.

  9. Human bladder cancer diagnosis using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sushmita; Wysock, James S.; Ng, Casey K.; Akhtar, Mohammed; Perner, Sven; Lee, Ming-Ming; Rubin, Mark A.; Maxfield, Frederick R.; Webb, Watt W.; Scherr, Douglas S.

    2009-02-01

    At the time of diagnosis, approximately 75% of bladder cancers are non-muscle invasive. Appropriate diagnosis and surgical resection at this stage improves prognosis dramatically. However, these lesions, being small and/or flat, are often missed by conventional white-light cystoscopes. Furthermore, it is difficult to assess the surgical margin for negativity using conventional cystoscopes. Resultantly, the recurrence rates in patients with early bladder cancer are very high. This is currently addressed by repeat cystoscopies and biopsies, which can last throughout the life of a patient, increasing cost and patient morbidity. Multiphoton endoscopes offer a potential solution, allowing real time, noninvasive biopsies of the human bladder, as well as an up-close assessment of the resection margin. While miniaturization of the Multiphoton microscope into an endoscopic format is currently in progress, we present results here indicating that Multiphoton imaging (using a bench-top Multiphoton microscope) can indeed identify cancers in fresh, unfixed human bladder biopsies. Multiphoton images are acquired in two channels: (1) broadband autofluorescence from cells, and (2) second harmonic generation (SHG), mostly by tissue collagen. These images are then compared with gold standard hematoxylin/eosin (H&E) stained histopathology slides from the same specimen. Based on a "training set" and a very small "blinded set" of samples, we have found excellent correlation between the Multiphoton and histopathological diagnoses. A larger blinded analysis by two independent uropathologists is currently in progress. We expect that the conclusion of this phase will provide us with diagnostic accuracy estimates, as well as the degree of inter-observer heterogeneity.

  10. Exploring the molecular chemistry and excitation in obscured luminous infrared galaxies. An ALMA mm-wave spectral scan of NGC 4418

    NASA Astrophysics Data System (ADS)

    Costagliola, F.; Sakamoto, K.; Muller, S.; Martín, S.; Aalto, S.; Harada, N.; van der Werf, P.; Viti, S.; Garcia-Burillo, S.; Spaans, M.

    2015-10-01

    Context. Extragalactic observations allow the study of molecular chemistry and excitation under physical conditions which may differ greatly from those found in the Milky Way. The compact, obscured nuclei (CON) of luminous infrared galaxies (LIRG) combine large molecular columns with intense infrared (IR), ultra-violet (UV), and X- radiation and represent ideal laboratories for the study of the chemistry of the interstellar medium (ISM) under extreme conditions. Aims: Our aim was to obtain for the first time a multi-band spectral scan of a LIRG, and to derive molecular abundances and excitation to be compared to other Galactic and extragalactic environments. Methods: We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418, spanning a total of 70.7 GHz in bands 3, 6, and 7. We use a combined local thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to identify the molecular species and to derive column densities and excitation temperatures. We derive molecular abundances and compare them with other Galactic and extragalactic sources by means of a principal component analysis. Results: We detect 317 emission lines from a total of 45 molecular species, including 15 isotopic substitutions and 6 vibrationally excited variants. Our LTE/NLTE fit find kinetic temperatures from 20 to 350 K, and densities between 105 and 107 cm-3. The spectrum is dominated by vibrationally excited HC3N, HCN, and HNC, with vibrational temperatures from 300 to 450 K. We find that the chemistry of NCG 4418 is characterized by high abundances of HC3N, SiO, H2S, and c-HCCCH but a low CH3OH abundance. A principal component analysis shows that NGC 4418 and Arp 220 share very similar molecular abundances and excitation, which clearly set them apart from other Galactic and extragalactic environments. Conclusions: Our spectral scan confirms that the chemical complexity in the nucleus of NGC 4418 is one of the highest ever observed outside our Galaxy. The similar molecular abundances observed toward NCG 4418 and Arp 220 are consistent with a hot gas-phase chemistry, with the relative abundances of SiO and CH3OH being regulated by shocks and X-ray driven dissociation. The bright emission from vibrationally excited species confirms the presence of a compact IR source, with an effective diameter smaller than 5 pc and brightness temperatures higher than 350 K. The molecular abundances and the vibrationally excited spectrum are consistent with a young AGN/starburst system. We suggest that NGC 4418 may be a template for a new kind of chemistry and excitation, typical of CON. Because of the narrow line widths and bright molecular emission, NGC 4418 is the ideal target for further studies of the chemistry in CONs. The spectrum in Fig. 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/582/A91Appendices are available in electronic form at http://www.aanda.org

  11. Near-infrared excited ultraviolet emitting upconverting phosphors as an internal light source in dry chemistry test strips for glucose sensing.

    PubMed

    Valta, T; Kale, V; Soukka, T; Horn, C

    2015-04-21

    Upconverting phosphors are inorganic crystals with interesting optical properties, including the ability to convert infrared radiation to emission at shorter wavelengths. In this paper we present the utilization of nanosized ?-NaYF4:Yb(3+),Tm(3+), synthesized in the presence of K(+), emitting at 365 nm under 980 nm excitation as an internal light source in glucose sensing dry chemistry test strips. The feasibility of the nanoparticles as an internal UV light source was compared to the use of an external broadband lamp. The results obtained from glucose measurements using UCNPs were in agreement with the traditional method based on measuring reflectance using an external UV light source. In addition the multiple emission peaks of UCNPs offered the possibility of using them as a control signal to account for various sources of error arising in the assay. The high penetration depth of the NIR-excitation made it also possible to excite the UCNPs through a layer of whole blood, giving more freedom to the design of the optical setup. PMID:25619498

  12. Near infrared excited micro-Raman spectra of 4:1 methanol-ethanol mixture and ruby fluorescence at high pressure

    NASA Astrophysics Data System (ADS)

    Wang, X. B.; Shen, Z. X.; Tang, S. H.; Kuok, M. H.

    1999-06-01

    Near infrared (NIR) lasers, as a new excitation source for Raman spectroscopy, has shown its unique advantages and is being increasingly used for some special samples, such as those emitting strong fluorescence in the visible region. This article focuses on some issues related to high-pressure micro-Raman spectroscopy using NIR excitation source. The Raman spectra of 4:1 methanol-ethanol mixture (4:1 M-E) show a linear variation in both Raman shifts and linewidths under pressure up to 18 GPa. This result is useful in distinguishing Raman scattering of samples from that of the alcohol mixture, an extensively used pressure-transmitting medium. The R1 fluorescence in the red region induced by two-photon absorption of the NIR laser is strong enough to be used as pressure scale. The frequency and line width of the R1 lines are very sensitive to pressure change and the glass transition of the pressure medium. Our results manifest that it is reliable and convenient to use NIR induced two-photon excited fluorescence of ruby for both pressure calibration and distribution of pressure in the 4:1 M-E pressure transmitting medium.

  13. Conjugated Polymer-Based Hybrid Nanoparticles with Two-Photon Excitation and Near-Infrared Emission Features for Fluorescence Bioimaging within the Biological Window.

    PubMed

    Lv, Yanlin; Liu, Peng; Ding, Hui; Wu, Yishi; Yan, Yongli; Liu, Heng; Wang, Xuefei; Huang, Fei; Zhao, Yongsheng; Tian, Zhiyuan

    2015-09-23

    Hybrid fluorescent nanoparticles (NPs) capable of fluorescing near-infrared (NIR) light (centered ?730 nm) upon excitation of 800 nm laser light were constructed. A new type of conjugated polymer with two-photon excited fluorescence (TPEF) feature, P-F8-DPSB, was used as the NIR-light harvesting component and the energy donor while a NIR fluorescent dye, DPA-PR-PDI, was used as the energy acceptor and the NIR-light emitting component for the construction of the fluorescent NPs. The hybrid NPs possess ? value up to 2.3 × 10(6) GM per particle upon excitation of 800 nm pulse laser. The excellent two-photon absorption (TPA) property of the conjugated polymer component, together with its high fluorescence quantum yield (?) up to 45% and the efficient energy transfer from the conjugated polymer to NIR-emitting fluorophore with efficiency up to 90%, imparted the hybrid NPs with TPEF-based NIR-input-NIR-output fluorescence imaging ability with penetration depth up to 1200 ?m. The practicability of the hybrid NPs for fluorescence imaging in Hela cells was validated. PMID:26340609

  14. Multiphoton polymerization using optical trap assisted nanopatterning

    NASA Astrophysics Data System (ADS)

    Leitz, Karl-Heinz; Tsai, Yu-Cheng; Flad, Florian; Schäffer, Eike; Quentin, Ulf; Alexeev, Ilya; Fardel, Romain; Arnold, Craig B.; Schmidt, Michael

    2013-06-01

    In this letter, we show the combination of multiphoton polymerization and optical trap assisted nanopatterning (OTAN) for the additive manufacturing of structures with nanometer resolution. User-defined patterns of polymer nanostructures are deposited on a glass substrate by a 3.5 ?m polystyrene sphere focusing IR femtosecond laser pulses, showing minimum feature sizes of ?/10. Feature size depends on the applied laser fluence and the bead surface spacing. A finite element model describes the intensity enhancement in the microbead focus. The results presented suggest that OTAN in combination with multiphoton processing is a viable technique for additive nanomanufacturing with sub-diffraction-limited resolution.

  15. DO THE INFRARED EMISSION FEATURES NEED ULTRAVIOLET EXCITATION? THE POLYCYCLIC AROMATIC HYDROCARBON MODEL IN UV-POOR REFLECTION NEBULAE

    E-print Network

    Draine, Bruce T.

    '' PAHs in reflection nebulae near stars as cool as Teff ¼ 3000 K can result in observable emis- sion at 6 illuminated by cool stars with Teff ¼ 3500, 4500, and 5000 K. These will allow comparison with future Space Infrared Telescope Facility observations of vdB 135 (Teff ¼ 3600 K), vdB 47 (Teff ¼ 4500 K), and vdB 101

  16. Studies on wide-field-of-view multiphoton imaging using the flexible clinical multiphoton tomograph MPTflex

    NASA Astrophysics Data System (ADS)

    Weinigel, Martin; Breunig, Hans Georg; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer; König, Karsten

    2012-03-01

    Multiphoton imaging systems are capable of high-resolution 3-D image acquisition of deep tissue. A first commercially available CE-certified biomedical system for subcelluar resolution of human skin has been launched by JenLab company with the DermaInspectR in 2002. The demand for more flexibility caused the development of the MPTflexR, which provides an increased flexibility and accessibility especially for clinical and cosmetic examinations. However the high resolution of clinical multiphoton tomographs are adherent with a small field-of-view (FOV) of about 360×360?m2. Especially time-consuming is the relocation of areas of interest (AOI) like lesions, sweat glands or hair shafts during a multiphoton examination. This limitation can be be overcome by macroscopic large-area (wide-field-ofview) multiphoton tomography, which is tested first within this work.

  17. Characterization of human normal and cancerous gastric submucosa based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Zhong, Jiazhao; Chen, G.; Liu, Y. C.; Zhuo, S. M.; Chen, J. X.; Yan, J.

    2012-03-01

    Gastric cancer is one of the most frequent cancers in the world; almost two-thirds of gastric cancer cases and deaths occur in less developed regions. The initial diagnosis of gastric cancer often is delayed because up to 80 percent of patients are asymptomatic during the early stages of stomach cancer. So the ability to perform real-time in vivo histological diagnosis for early gastric cancer at the cellular level during ongoing endoscopy is a long-standing goal of endoscopists. In this paper, using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), MPM images of human normal and cancerous gastric submucosa were obtained at excitation wavelength of 800 nm. The features such as the appearance of abnormal cells and the large loss of collagen in cancerous gastric submucosa were extracted to be as significant indicators to distinguish cancerous submucosa from normal submucosa. With the implementation of multiphoton microscopy concept in endoscopy applications, multiphoton endoscopy might realize in vivo histological diagnosis goal of endoscopists.

  18. Characterization of human normal and cancerous gastric submucosa based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Zhong, Jiazhao; Chen, G.; Liu, Y. C.; Zhuo, S. M.; Chen, J. X.; Yan, J.

    2011-11-01

    Gastric cancer is one of the most frequent cancers in the world; almost two-thirds of gastric cancer cases and deaths occur in less developed regions. The initial diagnosis of gastric cancer often is delayed because up to 80 percent of patients are asymptomatic during the early stages of stomach cancer. So the ability to perform real-time in vivo histological diagnosis for early gastric cancer at the cellular level during ongoing endoscopy is a long-standing goal of endoscopists. In this paper, using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), MPM images of human normal and cancerous gastric submucosa were obtained at excitation wavelength of 800 nm. The features such as the appearance of abnormal cells and the large loss of collagen in cancerous gastric submucosa were extracted to be as significant indicators to distinguish cancerous submucosa from normal submucosa. With the implementation of multiphoton microscopy concept in endoscopy applications, multiphoton endoscopy might realize in vivo histological diagnosis goal of endoscopists.

  19. Multiphoton blockades in pulsed regimes beyond the stationary limits

    E-print Network

    Hovsepyan, G H; Kryuchkyan, G Yu

    2014-01-01

    We demonstrate multiphoton blockades (PB) in the pulsed regime by using Kerr nonlinear dissipative resonator driven by a sequence of Gaussian pulses. It is shown that the results obtained for single-photon, two-photon and three-photon blockades in the pulsed excitation regime differ considerably from analogous results obtained for the case of continuous-wave (cw) driving. We strongly demonstrate that for the case of cw pumping of the Kerr-nonlinear resonator there are fundamental limits on populations of lower photonic number-states (with n = 0, 1, 2, 3). Thus, such detailed comparison demonstrates that PB due to excitation with a suitable photon pulses is realized beyond the fundamental limits established for cw excitations. We analyze photon-number effects and investigate phase-space properties of PB on the base of photon number populations, the second-order correlation functions and the Wigner functions in phase space. Generation of Fock states due to PB in the pulsed regime is analysed in details.

  20. Multiphoton ionization in ultrahigh optical fields: a statistical description

    SciTech Connect

    Egger, H.; Johann, U.; Luk, T.S.; Rhodes, C.K.

    1986-06-01

    The potential role of multiply excited states in multiphoton ionization of atoms under high-intensity ultraviolet laser radiation in the range of 10/sup 15/--10/sup 17/ W/cm/sup 2/ is discussed. Since the density of multiply excited states is sufficiently great to form a quasi-continuum, the coupling can be described by an average one-photon absorption cross section. A numerical flt with experimental data from xenon, produced by 193-nm radiation, assuming an autoionization rate of 10/sup 13/ sec/sup -1/, yields a cross section of 4.5 x 10/sup -19/ cm/sup 2/. The resulting transition rates indicate that the motion of the electrons is highly coherent, with a ratio of dephasing rate to excitation rate of --10/sup -2/. At 10/sup 17/ W/cm/sup 2/, the transition rate exceeds the optical frequency for 193-nm radiation by a factor of 30. This indicates that even for the shortest optical pulses, atoms start to interact violently with the optical field long before the peak intensity is reached and that unconventional theories will have to be developed if the observed phenomena are to be understood fully.

  1. Vibrational predesorption of carbon monoxide from sodium chloride at 20 K induced by resonant infrared laser excitation

    NASA Astrophysics Data System (ADS)

    Heidberg, Joachim; Stein, Helmust; Weiss, Helmut

    1987-06-01

    The linear vibrational absorption spectrum, the laser infrared absorption spectrum and the laser-induced desorption spectrum of carbon monoxide 13C 16O adsorbed on sodium chloride at 20 K were observed and found to coincide, the linewidth being 11±3 cm -1 the peak wavenumber 2107±2 cm -1. The energy of the fundamental internal vibration of adsorbed CO is greater than the adsorption energy. The resonant laser-induced process detected is described as a vibrational predesorption.

  2. Vibrational predesorption of carbon monoxide from sodium chloride at 20 K induced by resonant infrared laser excitation

    NASA Astrophysics Data System (ADS)

    Heidberg, Joachim; Stein, Helmut; Weiss, Helmut

    The linear vibrational absorption spectrum, the laser infrared absorption spectrum and the laser-induced desorption spectrum of carbon monoxide 13C 16O adsorbed on sodium chloride at 20 K were observed and found to coincide, the linewidth being 11±3 cm -1, the peak wavenumber 2107±2 cm -1. The energy of the fundamental internal vibration of adsorbed CO is greater than the adsorption energy. The resonant laser-induced process detected is described as a vibrational predesorption.

  3. Polymer microcantilevers fabricated via multiphoton absorption polymerization

    E-print Network

    Teich, Malvin C.

    Polymer microcantilevers fabricated via multiphoton absorption polymerization Z. Bayindir, Y. Sun polymer cantilevers. Atomic force microscopy has been used to characterize the mechanical properties orders of magnitude smaller than would be predicted from the properties of the bulk polymer.6 If correct

  4. The 3.1 ?m Infrared Spectra of Vibrationally Excited C_3 in a Supersonic Plasma Jet

    NASA Astrophysics Data System (ADS)

    Zhao, Dongfeng; Doney, Kirstin D.; Linnartz, Harold

    2014-06-01

    The linear triatomic carbon (C_3), one of the most important molecules that have been identified in both dense and diffuse interstellar environments, has attracted great interest to astronomers and astrochemists. It is also of fundamental interest as it serves as a benchmark system for quantum chemistry. In this presentation, we report the high-resolution infrared spectra of C_3 in the 3.1 ?m region. The C_3 molecules are produced in a supersonic pulsed planar plasma by discharging a propyne/helium/argon gas mixture. Continuous-wave cavity ringdown spectroscopy is used to record the infrared absorption spectra of C_3. In total, eighteen vibrational bands are observed in the 3110 - 3290 wn range, and sixteen of them are reported for the first time. It is found that, the vibrational temperatures for the two CC stretch modes of C_3 are up to 8000 K in our plasma source, allowing to experimentally determine the ro-vibrational levels of C_3 to the 10 000 wn region. Accurate spectroscopic parameters are obtained from the detailed analysis of our spectra. The molecular data reported here are used to test the very recent theoretical work beyond the 'gold standard' P. Botschiwina, private communication.} for a comprehensive understanding of the ground-state potential energy surface of C_3.

  5. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    SciTech Connect

    Chu, P.M.Y.

    1991-10-01

    The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V{yields}T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH{sub 3} production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  6. http://biotech.nature.com JULY 2001 VOLUME 19 nature biotechnology Multiphoton-evoked color change of DsRed as an

    E-print Network

    Parker, Ian

    transfer (FRET). The "greening" effect occurs in live mammalian cells at the cellular and subcellular Multiphoton imaging of DsRed. We used a femtosecond infrared laser and a video-rate scanning confocal microscope for multipho- ton imaging of mammalian cell lines transiently transfected with DsRed 24­72 h

  7. Discrimination of zeolites and beryllium containing silicates using portable Raman spectroscometric equipment with near-infrared excitation.

    PubMed

    Jehli?ka, J; Vandenabeele, P; Edwards, H G M

    2012-02-01

    In this paper Raman spectra were obtained for a series of zeolites (thomsonite, stilbite, natrolite) and beryllium containing silicates (beryl, chrysoberyl, euclase, phenacite, bavenite, milarite) using a portable Raman specrometer with a 785 nm laser excitation to show the possibility to apply this setting for unambiguous detection and discrimination of these silicate minerals. Obtained spectra contain the most intense Raman bands at the same positions ±2-4 cm(-1) as reported in the literature. The use of these bands permits the unambiguous identification of these phases. Data show the possibility to discriminate individual species of similar whitish color and aspect. Measurements showed an excellent correspondence of Raman bands obtained using the portable system and a laboratory Raman microspectrometer (with the same excitation laser wavelenght). However, for several minerals of these groups (chrysoberyl, bertrandite, chiavennite) Raman spectra were not of sufficient quality to permit unambiguous identification. The reasons are discussed. Raman spectrum of chiavennite CaMnBe(2)Si(5)O(13)(OH)(2)·2(H(2)O) - a transformation product occurring together with bavenite on the surface of beryl crystals was obtained for the first time using the laboratory Raman spectrometer. PMID:22099060

  8. Multi-Photon Interference and Temporal Distinguishability of Photons

    E-print Network

    Z. Y. Ou

    2007-08-24

    A number of recent interference experiments involving multiple photons are reviewed. These experiments include generalized photon bunching effects, generalized Hong-Ou-Mandel interference effects and multi-photon interferometry for demonstrations of multi-photon de Broglie wavelength. The multi-photon states used in these experiments are from two pairs of photons in parametric down-conversion. We find that the size of the interference effect in these experiments, characterized by the visibility of interference pattern, is governed by the degree of distinguishability among different pairs of photons. Based on this discovery, we generalize the concept of multi-photon temporal distinguishability and relate it to a number of multi-photon interference effects. Finally, we make an attempt to interpret the coherence theory by the multi-photon interference via the concept of temporal distinguishability of photons.

  9. Simulated infrared emission spectra of highly excited polyatomic molecules: a detailed model of the PAH-UIR hypothesis

    NASA Technical Reports Server (NTRS)

    Cook, D. J.; Saykally, R. J.

    1998-01-01

    A detailed description of the polycyclic aromatic hydrocarbon (PAH)/unidentified infrared band (UIR) mechanism is presented in which experimental spectral bandshape functions are used to simulate IR emission spectra for individual molecules. These spectra are additively superimposed to produce a conglomerate spectrum representative of a family of PAH molecules. Ab initio vibrational frequencies and intensities for nine PAHs (neutral and cationic) as large as ovalene are used in conjunction with measured bandshape and temperature-dependent redshift data to simulate the UIR bands. The calculated spectra of cations provide a closer match to the UIRs than do those of the neutrals. However, the PAH cations used in the simulations fail to reproduce the details of the UIR emission spectra. The discrepancies are potentially alleviated if both larger PAHs and a greater number of PAHs were included in the simulation.

  10. Generation of multi-photon entanglement

    E-print Network

    Dong Xie; An Min Wang

    2013-12-27

    We propose a new scheme to generate the multi-photon entanglement via two steps, that is, first to utilize the superconductor to create the multi-quantum-dot entanglement, and then to use the input photon to transfer it into the multi-photon entanglement. Moreover, the maximum probability for the swap of photon and quantum-dot qubits is close to unit for a single input Gaussian photon. More importantly, by mapping the multi-quantum-dot state into the coherent states of oscillators, such as cavity modes, the multi-quantum-dot entanglement in our scheme can be protected from the decoherence induced by the noise. Thus, it is possible to generate more than eight spatially separated entangled photons in the realistic experimental conditions.

  11. Multi-photon optical rotation by molecules

    NASA Astrophysics Data System (ADS)

    Cameron, R.; Tabisz, G. C.

    2001-05-01

    Forward scattering of polarized light by a chiral molecule results in optical rotation. Ordinary optical rotation, a single-photon effect, is independent of intensity, I. Multi-photon optical rotation is proportional to I^N-1, where N is the number of photons involved the scattering event. The ordinary optical rotation changes with temperature, and so the absorption of light can also cause an intensity-dependent change in optical rotation. We used a polarimeter to measure the change in optical rotation with light intensity for several molecules in solution: sucrose, borneol, uridine and phenylalanine. Making use of Faraday rotation, we added a time-dependent rotation of the light to our apparatus. This allowed us to use Fourier analysis to separate the multi-photon optical rotation from the temperature change in ordinary optical rotation and improved the signal-to-noise.

  12. Clinical optical coherence tomography combined with multiphoton tomography for evaluation of several skin disorders

    NASA Astrophysics Data System (ADS)

    König, Karsten; Speicher, Marco; Bückle, Rainer; Reckfort, Julia; McKenzie, Gordon; Welzel, Julia; Koehler, Martin J.; Elsner, Peter; Kaatz, Martin

    2010-02-01

    The first clinical trial of optical coherence tomography (OCT) combined with multiphoton tomography (MPT) and dermoscopy is reported. State-of-the-art (i) OCT systems for dermatology (e.g. multibeam swept source OCT), (ii) the femtosecond laser multiphoton tomograph DermaInspectTM, and (iii) digital dermoscopes were applied to 47 patients with a diversity of skin diseases and disorders such as skin cancer, psoriasis, hemangioma, connective tissue diseases, pigmented lesions, and autoimmune bullous skin diseases. Dermoscopy, also called 'epiluminescent microscopy', provides two-dimensional color images of the skin surface. OCT imaging is based on the detection of optical reflections within the tissue measured interferometrically whereas nonlinear excitation of endogenous fluorophores and the second harmonic generation are the bases of MPT images. OCT cross sectional "wide field" image provides a typical field of view of 5 x 2 mm2 and offers fast information on the depth and the volume of the investigated lesion. In comparison, multiphoton tomography presents 0.36 x 0.36 mm2 horizontal or diagonal sections of the region of interest within seconds with submicron resolution and down to a tissue depth of 200 ?m. The combination of OCT and MPT provides a synergistic optical imaging modality for early detection of skin cancer and other skin diseases.

  13. Ultralow-threshold multiphoton-pumped lasing from colloidal nanoplatelets in solution

    NASA Astrophysics Data System (ADS)

    Li, Mingjie; Zhi, Min; Zhu, Hai; Wu, Wen-Ya; Xu, Qing-Hua; Jhon, Mark Hyunpong; Chan, Yinthai

    2015-09-01

    Although multiphoton-pumped lasing from a solution of chromophores is important in the emerging fields of nonlinear optofluidics and bio-photonics, conventionally used organic dyes are often rendered unsuitable because of relatively small multiphoton absorption cross-sections and low photostability. Here, we demonstrate highly photostable, ultralow-threshold multiphoton-pumped biexcitonic lasing from a solution of colloidal CdSe/CdS nanoplatelets within a cuvette-based Fabry-Pérot optical resonator. We find that colloidal nanoplatelets surprisingly exhibit an optimal lateral size that minimizes lasing threshold. These nanoplatelets possess very large gain cross-sections of 7.3 × 10-14 cm2 and ultralow lasing thresholds of 1.2 and 4.3 mJ cm-2 under two-photon (?exc=800 nm) and three-photon (?exc=1.3 ?m) excitation, respectively. The highly polarized emission from the nanoplatelet laser shows no significant photodegradation over 107 laser shots. These findings constitute a more comprehensive understanding of the utility of colloidal semiconductor nanoparticles as the gain medium in high-performance frequency-upconversion liquid lasers.

  14. Ultralow-threshold multiphoton-pumped lasing from colloidal nanoplatelets in solution.

    PubMed

    Li, Mingjie; Zhi, Min; Zhu, Hai; Wu, Wen-Ya; Xu, Qing-Hua; Jhon, Mark Hyunpong; Chan, Yinthai

    2015-01-01

    Although multiphoton-pumped lasing from a solution of chromophores is important in the emerging fields of nonlinear optofluidics and bio-photonics, conventionally used organic dyes are often rendered unsuitable because of relatively small multiphoton absorption cross-sections and low photostability. Here, we demonstrate highly photostable, ultralow-threshold multiphoton-pumped biexcitonic lasing from a solution of colloidal CdSe/CdS nanoplatelets within a cuvette-based Fabry-Pérot optical resonator. We find that colloidal nanoplatelets surprisingly exhibit an optimal lateral size that minimizes lasing threshold. These nanoplatelets possess very large gain cross-sections of 7.3 × 10(-14)?cm(2) and ultralow lasing thresholds of 1.2 and 4.3?mJ?cm(-2) under two-photon (?exc=800?nm) and three-photon (?exc=1.3??m) excitation, respectively. The highly polarized emission from the nanoplatelet laser shows no significant photodegradation over 10(7) laser shots. These findings constitute a more comprehensive understanding of the utility of colloidal semiconductor nanoparticles as the gain medium in high-performance frequency-upconversion liquid lasers. PMID:26419950

  15. Ultralow-threshold multiphoton-pumped lasing from colloidal nanoplatelets in solution

    PubMed Central

    Li, Mingjie; Zhi, Min; Zhu, Hai; Wu, Wen-Ya; Xu, Qing-Hua; Jhon, Mark Hyunpong; Chan, Yinthai

    2015-01-01

    Although multiphoton-pumped lasing from a solution of chromophores is important in the emerging fields of nonlinear optofluidics and bio-photonics, conventionally used organic dyes are often rendered unsuitable because of relatively small multiphoton absorption cross-sections and low photostability. Here, we demonstrate highly photostable, ultralow-threshold multiphoton-pumped biexcitonic lasing from a solution of colloidal CdSe/CdS nanoplatelets within a cuvette-based Fabry–Pérot optical resonator. We find that colloidal nanoplatelets surprisingly exhibit an optimal lateral size that minimizes lasing threshold. These nanoplatelets possess very large gain cross-sections of 7.3 × 10?14?cm2 and ultralow lasing thresholds of 1.2 and 4.3?mJ?cm?2 under two-photon (?exc=800?nm) and three-photon (?exc=1.3??m) excitation, respectively. The highly polarized emission from the nanoplatelet laser shows no significant photodegradation over 107 laser shots. These findings constitute a more comprehensive understanding of the utility of colloidal semiconductor nanoparticles as the gain medium in high-performance frequency-upconversion liquid lasers. PMID:26419950

  16. Medium-induced multi-photon radiation

    E-print Network

    Hao Ma; Carlos A. Salgado; Konrad Tywoniuk

    2011-05-29

    We study the spectrum of multi-photon radiation off a fast quark in medium in the BDMPS/ASW approach. We reproduce the medium-induced one-photon radiation spectrum in dipole approximation, and go on to calculate the two-photon radiation in the Moli\\`{e}re limit. We find that in this limit the LPM effect holds for medium-induced two-photon ladder emission.

  17. In vivo confocal and multiphoton microendoscopy

    PubMed Central

    Kim, Pilhan; Puoris’haag, Mehron; Côté, Daniel; Lin, Charles P.; Yun, Seok H.

    2009-01-01

    The ability to conduct high-resolution fluorescence imaging in internal organs of small animal models in situ and over time can make a significant impact in biomedical research. Toward this goal, we developed a real-time confocal and multiphoton endoscopic imaging system. Using 1-mm-diameter endoscopes based on gradient index lenses, we demonstrate video-rate multicolor multimodal imaging with cellular resolution in live mice. PMID:18315346

  18. Multiphoton ghost imaging with classical light

    E-print Network

    I. N. Agafonov; M. V. Chekhova; A. N. Penin

    2009-12-02

    One of the possible types of n-th order ghost imaging is experimentally performed using multi-photon (higher-order) intensity correlations of pseudothermal light. It is shown that although increasing the order of intensity correlations leads to the growth of ghost imaging visibility, it at the same time reduces the signal-to-noise ratio. Therefore, ghost imaging with thermal light is optimal in the second order in the intensity.

  19. Video-rate resonant scanning multiphoton microscopy

    PubMed Central

    Kirkpatrick, Nathaniel D.; Chung, Euiheon; Cook, Daniel C.; Han, Xiaoxing; Gruionu, Gabriel; Liao, Shan; Munn, Lance L.; Padera, Timothy P.; Fukumura, Dai; Jain, Rakesh K.

    2013-01-01

    The abnormal tumor microenvironment fuels tumor progression, metastasis, immune suppression, and treatment resistance. Over last several decades, developments in and applications of intravital microscopy have provided unprecedented insights into the dynamics of the tumor microenvironment. In particular, intravital multiphoton microscopy has revealed the abnormal structure and function of tumor-associated blood and lymphatic vessels, the role of aberrant tumor matrix in drug delivery, invasion and metastasis of tumor cells, the dynamics of immune cell trafficking to and within tumors, and gene expression in tumors. However, traditional multiphoton microscopy suffers from inherently slow imaging rates—only a few frames per second, thus unable to capture more rapid events such as blood flow, lymphatic flow, and cell movement within vessels. Here, we report the development and implementation of a video-rate multiphoton microscope (VR-MPLSM) based on resonant galvanometer mirror scanning that is capable of recording at 30 frames per second and acquiring intravital multispectral images. We show that the design of the system can be readily implemented and is adaptable to various experimental models. As examples, we demonstrate the utility of the system to directly measure flow within tumors, capture metastatic cancer cells moving within the brain vasculature and cells in lymphatic vessels, and image acute responses to changes in a vascular network. VR-MPLSM thus has the potential to further advance intravital imaging and provide new insight into the biology of the tumor microenvironment. PMID:24353926

  20. Collective excitation of Rydberg-atom ensembles beyond the superatom model.

    PubMed

    Gärttner, Martin; Whitlock, Shannon; Schönleber, David W; Evers, Jörg

    2014-12-01

    In an ensemble of laser-driven atoms involving strongly interacting Rydberg states, the steady-state excitation probability is usually substantially suppressed. In contrast, here we identify a regime in which the Rydberg excited fraction is enhanced by the interaction. This effect is associated with the buildup of many-body coherences induced by coherent multiphoton excitations between collective states. The excitation enhancement should be observable under currently existing experimental conditions and may serve as a direct probe for the presence of coherent multiphoton dynamics involving collective quantum states. PMID:25526126

  1. Identification of dirty necrosis in colorectal carcinoma based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Li, Lianhuang; Jiang, Weizhong; Yang, Yinghong; Chen, Zhifen; Feng, Changyin; Li, Hongsheng; Guan, Guoxian; Chen, Jianxin

    2014-06-01

    Dirty necrosis within glandular lumina is often considered as a characteristic of colorectal carcinomas (CRCs) that is a diagnostically useful feature of CRCs with DNA microsatellite instability (MSI). Multiphoton microscopy (MPM), which is based on the second-harmonic generation and two-photon excited fluorescence signals, was used to identify dirty necrosis. Our results demonstrated that MPM has the ability to exhibit the microstructure of dirty necrosis and the signal intensity as well as an emission spectrum that can help to differentiate dirty necrosis from cancer cells. These findings indicate that MPM may be helpful in distinguishing MSI colorectal carcinoma via the identification of dirty necrosis.

  2. Optimal spectral filtering in soliton self-frequency shift for deep-tissue multiphoton microscopy.

    PubMed

    Wang, Ke; Qiu, Ping

    2015-05-01

    Tunable optical solitons generated by soliton self-frequency shift (SSFS) have become valuable tools for multiphoton microscopy (MPM). Recent progress in MPM using 1700 nm excitation enabled visualizing subcortical structures in mouse brain in vivo for the first time. Such an excitation source can be readily obtained by SSFS in a large effective-mode-area photonic crystal rod with a 1550-nm fiber femtosecond laser. A longpass filter was typically used to isolate the soliton from the residual in order to avoid excessive energy deposit on the sample, which ultimately leads to optical damage. However, since the soliton was not cleanly separated from the residual, the criterion for choosing the optimal filtering wavelength is lacking. Here, we propose maximizing the ratio between the multiphoton signal and the n'th power of the excitation pulse energy as a criterion for optimal spectral filtering in SSFS when the soliton shows dramatic overlapping with the residual. This optimization is based on the most efficient signal generation and entirely depends on physical quantities that can be easily measured experimentally. Its application to MPM may reduce tissue damage, while maintaining high signal levels for efficient deep penetration. PMID:25950644

  3. Optimal spectral filtering in soliton self-frequency shift for deep-tissue multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Ke; Qiu, Ping

    2015-05-01

    Tunable optical solitons generated by soliton self-frequency shift (SSFS) have become valuable tools for multiphoton microscopy (MPM). Recent progress in MPM using 1700 nm excitation enabled visualizing subcortical structures in mouse brain in vivo for the first time. Such an excitation source can be readily obtained by SSFS in a large effective-mode-area photonic crystal rod with a 1550-nm fiber femtosecond laser. A longpass filter was typically used to isolate the soliton from the residual in order to avoid excessive energy deposit on the sample, which ultimately leads to optical damage. However, since the soliton was not cleanly separated from the residual, the criterion for choosing the optimal filtering wavelength is lacking. Here, we propose maximizing the ratio between the multiphoton signal and the n'th power of the excitation pulse energy as a criterion for optimal spectral filtering in SSFS when the soliton shows dramatic overlapping with the residual. This optimization is based on the most efficient signal generation and entirely depends on physical quantities that can be easily measured experimentally. Its application to MPM may reduce tissue damage, while maintaining high signal levels for efficient deep penetration.

  4. Experimental multi-photon entanglement and quantum enhanced

    E-print Network

    Weinfurter, Harald

    Experimental multi-photon entanglement and quantum enhanced metrology Roland Patrik Krischek M¨unchen 2011 #12;#12;Experimental multi-photon entanglement and quantum enhanced metrology Roland Patrik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4 Optical quantum enhanced metrology 77 4.1 Useful multi-particle entanglement and sub shot noise

  5. Infrared-active optical phonons and magnetic excitations in the hexagonal manganites RMnO3 (R =Ho, Er, Tm, Yb, and Lu)

    NASA Astrophysics Data System (ADS)

    Basistyy, R.; Stanislavchuk, T. N.; Sirenko, A. A.; Litvinchuk, A. P.; Kotelyanskii, M.; Carr, G. L.; Lee, N.; Wang, X.; Cheong, S.-W.

    2014-07-01

    Optical properties of hexagonal multiferroic oxides RMnO3, where R=Ho, Er, Tm, Yb, and Lu, have been studied in the far-infrared spectral range between 100 and 2000 cm-1 and temperatures between 1.5 and 300 K by means of several experimental techniques: Mueller matrix spectroscopic ellipsometry, rotating analyzer ellipsometry, and optical transmission spectroscopy. Spectra of the optical phonons are described in terms of the temperature dependencies of their frequency, damping, and oscillator strength. For all studies, oxide materials' clear signatures of the spin-phonon interaction have been found below the temperature of the antiferromagnetic phase transition TN due to magnetic ordering of Mn3+ spins. A decrease of the ionic radius for R3+ ions between Ho3+ and Lu3+ in the corresponding RMnO3 compounds resulted in systematic variation of the frequency for several optical phonons. A magnetic excitation at ˜190 cm-1 was observed at low temperatures below TN and interpreted as resulting from two-magnon absorption.

  6. Organic matter humification in vermifiltration process for domestic sewage sludge treatment by excitation-emission matrix fluorescence and Fourier transform infrared spectroscopy.

    PubMed

    Li, Xiaowei; Xing, Meiyan; Yang, Jian; Zhao, Limin; Dai, Xiaohu

    2013-10-15

    Performance of a conventional biofilter (BF) and two vermifilters (VFs, different heights) containing earthworms was investigated for domestic sewage sludge (DWS) treatment. Humic-acid like (HAL) fraction isolated from the influent sludge (IS) and effluent sludge of BF (ESBF) and VFs (ESVFs) were determined the elemental and functional composition, and structural characteristics using various analytical approaches. Results showed that performance of DWS treatment in the VFs was preferable to that in the BF. With respect to IS-HAL and ESBF-HAL, ESVFs-HAL had low C, H and N contents and C/O ratio, and high O, carboxyl and phenolic OH group contents, and C/N, C/H and E4/E6 ratios, and large molecular weight. The excitation-emission (Ex/Em) matrix spectra revealed that an additional peak was found at Ex/Em wavelength pairs of 345/435 nm in ESVFs-HAL. Further, Fourier transform infrared spectra showed that vermifiltration led to the loss of aliphatic materials and carbohydrates, and the enrichment of carbonyl and phenolic OH groups in HAL fractions. Additionally, the increase in VF height seemed to accelerate humification degree of organic matter in the effluent sludge. In summary, vermifiltration is alternate technology for transformation of organic matter into humic substances, and thus improves quality of DWS as soil organic fertilizer. PMID:23981770

  7. Infrared photodissociation of a water molecule from a flexible molecule-H{sub 2}O complex: Rates and conformational product yields following XH stretch excitation

    SciTech Connect

    Clarkson, Jasper R.; Herbert, John M.; Zwier, Timothy S.

    2007-04-07

    Infrared-ultraviolet hole-burning and hole-filling spectroscopies have been used to study IR-induced dissociation of the tryptamine{center_dot}H{sub 2}O and tryptamine{center_dot}D{sub 2}O complexes. Upon complexation of a single water molecule, the seven conformational isomers of tryptamine collapse to a single structure that retains the same ethylamine side chain conformation present in the most highly populated conformer of tryptamine monomer. Infrared excitation of the tryptamine{center_dot}H{sub 2}O complex was carried out using a series of infrared absorptions spanning the range of 2470-3715 cm{sup -1}. The authors have determined the conformational product yield over this range and the dissociation rate near threshold, where it is slow enough to be measured by our methods. The observed threshold for dissociation occurred at 2872 cm{sup -1} in tryptamine{center_dot}H{sub 2}O and at 2869 cm{sup -1} in tryptamine{center_dot}D{sub 2}O, with no dissociation occurring on the time scale of the experiment ({approx}2 {mu}s) at 2745 cm{sup -1}. The dissociation time constants varied from {approx}200 ns for the 2869 cm{sup -1} band of tryptamine{center_dot}D{sub 2}O to {approx}25 ns for the 2872 cm{sup -1} band of tryptamine{center_dot}H{sub 2}O. This large isotope dependence is associated with a zero-point energy effect that increases the binding energy of the deuterated complex by {approx}190 cm{sup -1}, thereby reducing the excess energy available at the same excitation energy. At all higher energies, the dissociation lifetime was shorter than the pulse duration of our lasers (8 ns). At all wavelengths, the observed products in the presence of collisions are dominated by conformers A and B of tryptamine monomer, with small contributions from the other minor conformers. In addition, right at threshold (2869 cm{sup -1}), tryptamine{center_dot}D{sub 2}O dissociates exclusively to conformer A in the absence of collisions with helium, while both A and B conformational products are observed in the presence of collisions with helium. Using resolution-of-identity approximation to second-order Moeller-Plesset binding energies extrapolated to the complete basis set limit and harmonic vibrational frequencies and transition states calculated at the density functional limit B3LYP/6-31+G{sup *} level of theory, Rice-Ramsperger-Kassel-Marcus (RRKM) predictions for the dissociation, isomerization, and water shuttling rates as a function of energy are made. At threshold, the experimental dissociation rate is almost 10{sup 3} faster than RRKM predictions. Reasons for this apparent non-RRKM behavior will be discussed.

  8. Achieving molecular selectivity in imaging using multiphoton Raman spectroscopy techniques

    SciTech Connect

    Holtom, Gary R. ); Thrall, Brian D. ); Chin, Beek Yoke ); Wiley, H Steven ); Colson, Steven D. )

    2000-12-01

    In the case of most imaging methods, contrast is generated either by physical properties of the sample (Differential Image Contrast, Phase Contrast), or by fluorescent labels that are localized to a particular protein or organelle. Standard Raman and infrared methods for obtaining images are based upon the intrinsic vibrational properties of molecules, and thus obviate the need for attached flurophores. Unfortunately, they have significant limitations for live-cell imaging. However, an active Raman method, called Coherent Anti-Stokes Raman Scattering (CARS), is well suited for microscopy, and provides a new means for imaging specific molecules. Vibrational imaging techniques, such as CARS, avoid problems associated with photobleaching and photo-induced toxicity often associated with the use of fluorescent labels with live cells. Because the laser configuration needed to implement CARS technology is similar to that used in other multiphoton microscopy methods, such as two -photon fluorescence and harmonic generation, it is possible to combine imaging modalities, thus generating simultaneous CARS and fluorescence images. A particularly powerful aspect of CARS microscopy is its ability to selectively image deuterated compounds, thus allowing the visualization of molecules, such as lipids, that are chemically indistinguishable from the native species.

  9. The multiphoton ionization of uranium hexafluoride. Revision 1

    SciTech Connect

    Armstrong, D.P.

    1992-05-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF{sub 6} have been conducted using focused light from the Nd:YAG laser fundamental ({lambda}=1064 nm) and its harmonics ({lambda}=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF{sub x}{sup +} fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U{sup n+} ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U{sup 2+}) intensity is much greater than that of the singly-charged uranium ion (U{sup +}). For the case of the tunable dye laser experiments, the U{sup n+} (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U{sup 2+} ion and the absence or very small intensities of UF{sub x}{sup +} fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule.

  10. Multiphoton absorption of HF laser photons by molecules containing a hydroxyl group

    NASA Astrophysics Data System (ADS)

    McAlpine, Robert D.; Evans, D. K.; McClusky, F. K.

    1980-08-01

    Multiphoton absorption (MPA) of HF laser radiation has been studied, as a function of pressure (15 Pa to 1.3 kPa) and fluence (2 mJ/cm2 to 75 J/cm2) for the series: water, methanol, methan-d3-ol, ethanol, and 2,2,2-trifluoroethanol. As the group attached to the -OH is made more complex, the quasicontinuum occurs after fewer excitation steps, and under ''collisionless'' conditions, the same degree of multiphoton excitation is found to require a lower fluence. For water, at pressures between 73 Pa and 1.3 kPa, the cross sections are considerably lower than those for the other molecules, and MPA requires fluences in excess of ˜75 J/cm2. The remaining molecules divide into two groups, the ''small'' molecules (CH3OH and CD3OH) and the ''large'' molecules (C2H5OH and CF3CH2OH). For the small molecules at low pressures, the cross sections decrease with increasing fluence, an effect which is thought to be due to anharmonic bottlenecking. As pressure increases, the fluence dependence of the cross sections disappear. For the large molecules, anharmonic bottlenecking appears to be reduced, due to the greater density of states, and cross sections increase with increasing fluence according to the empirical form: ?(E, P)=K'Eb'Pa (where P is pressure, E is fluence and b', a, and K' are constants). The facility of HF laser-induced collisionless multiphoton dissociation of the -OH containing molecules is discussed in light of these results.

  11. In vivo non-invasive multiphoton tomography of human skin

    NASA Astrophysics Data System (ADS)

    König, Karsten; Riemann, Iris; Ehlers, Alexander; Le Harzic, Ronan

    2005-10-01

    High resolution non-invasive 3D imaging devices are required to detect pathogenic microorganisms such as Anthrax spores, bacteria, viruses, fungi and chemical agents entering biological tissues such as the epidermis. Due to the low light penetration depth and the biodamage potential, ultraviolet light sources can not be employed to realize intratissue imaging of bio- and chemohazards. We report on the novel near infrared laser technology multiphoton tomography and the high resolution 4D imaging tool DermaInspect for non-invasive detection of intratissue agents and their influence on cellular metabolism based on multiphoton autofluorescence imaging (MAI) and second harmonic generation (SHG). Femtosecond laser pulses in the spectral range of 750 nm to 850 nm have been used to image in vivo human skin with subcellular spatial and picosecond temporal resolution. The non-linear induced autofluorescence of both, skin tissues and microorganisms, originates mainly from naturally endogenous fluorophores/protein structures like NAD(P)H, flavins, keratin, collagen, elastin, porphyrins and melanin. Bacteria emit in the blue/green spectral range due to NAD(P)H and flavoproteins and, in certain cases, in the red spectral range due to the biosynthesis of Zn-porphyrins, coproporphyrin and protoporphyrin. Collagen and exogenous non-centrosymmetric molecules can be detected by SHG signals. The system DermaInspect consists of a wavelength-tunable compact 80/90 MHz Ti:sapphire laser, a scan module with galvo scan mirrors, piezo-driven objective, fast photon detector and time-resolved single photon counting unit. It can be used to perform optical sectioning and 3D autofluorescence lifetime imaging (?-mapping) with 1 ?m spatial resolution and 270 ps temporal resolution. The parameter fluorescence lifetime depends on the type of fluorophore and its microenvironment and can be used to distinguish bio- and chemohazards from cellular background and to gain information for pathogen identification. The novel in vivo non-invasive imaging system offers the possibility to detect and to localize CB agents in tissues and to gain information on their impact on respiratory chain activity, cell division and metabolism. The system DermaInspect can also be used to detect food and water contamination.

  12. Molecular photoelectron angular distribution rotations in multi-photon resonant ionization of H{sub 2}{sup +} by circularly polarized ultraviolet laser pulses

    SciTech Connect

    Yuan, Kai-Jun Chelkowski, Szczepan; Bandrauk, André D.

    2015-04-14

    We study effects of pulse durations on molecular photoelectron angular distributions (MPADs) in ultrafast circular polarization ultraviolet resonant ionization processes. Simulations performed on aligned H{sub 2}{sup +} by numerically solving time dependent Schrödinger equations show rotations of MPADs with respect to the molecular symmetry axes. It is found that in multi-photon resonant ionization processes, rotation angles are sensitive to pulse durations, which we attribute to the coherent resonant excitation between the ground state and the intermediate excited electronic state induced by Rabi oscillations. Multi-photon nonresonant and single photon ionization processes are simulated and compared which exhibit a constant rotation angle. An asymmetry parameter is introduced to describe the pulse duration sensitivity by perturbation theory models. Influence of pulse frequency detunings on MPADs is also investigated where oscillations of rotations are absent at long pulse durations due to nonresonance excitation.

  13. Minimally invasive multiphoton and harmonic generation imaging of extracellular matrix structures in lung airway and related diseases.

    PubMed

    Abraham, Thomas; Hirota, Jeremy A; Wadsworth, Samuel; Knight, Darryl A

    2011-10-01

    Multiphoton microscopy has become a powerful imaging method for minimally invasive evaluation of extracellular matrix (ECM) and cellular structures deep within tissues in their native environments. This technology, which uses ultra-short femto-second laser pulses as the excitation source, is efficient in multiphoton excitation fluorescence (MPEF) of endogenously fluorescent macromolecular systems and induction of highly specific second harmonic generation (SHG) signals from non-centrosymmetric macromolecules such as fibrillar collagens. Both these signals can be captured simultaneously to provide spatially resolved 3D structural organization of ECM as well as cellular morphologies in lung or airway tissue with spectral specificity and sensitivity. These imaging modalities are minimally invasive since structures deep within tissues can be visualized without the need for tissue fixation and/or sectioning. Much of the traditional histological and chemical procedures associated with conventional microscopy methods, which may alter native structure of lung tissue samples, can be circumvented to generate more accurate 3D morphological and fine structural information. In addition to outlining basic principles associated with MPEF and SHG microscopy methods, this review reports potential uses of these high resolution imaging modalities in lung structural imaging. We place special emphasis on imaging 3D structural features of airways, visualizing and quantifying ECM remodeling associated with mouse asthma model as well as the potential uses for multiphoton microscopy in in vitro airway applications. PMID:21497667

  14. Multiphoton ionization of large water clusters

    SciTech Connect

    Apicella, B.; Li, X.; Passaro, M.; Spinelli, N.; Wang, X.

    2014-05-28

    Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.

  15. Nonperturbative multiphoton processes and electron-positron pair production

    SciTech Connect

    Hatsagortsyan, K. Z.; Mueller, C.; Keitel, C. H.

    2006-04-07

    Various regimes of pair production in laser fields are analyzed. Particularly, the question of the observability of pair production in a nonperturbative multiphoton regime is discussed. A simple heuristic method is employed which gives order-of-magnitude estimates for probabilities of multiphoton processes and allows to describe its main features. The method is initially probed upon the known process of pair production in a Coulomb and a strong laser field. Then it is applied to the nonperturbative multiphoton regime of the pair production process in a standing laser wave.

  16. Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and handheld probe.

    PubMed

    Liu, Gangjun; Kieu, Khanh; Wise, Frank W; Chen, Zhongping

    2011-01-01

    We report on the development of a compact multiphoton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature probe. The all normal dispersion fiber femtosecond laser has a central wavelength of 1.06 ?m, pulse width of 125 fs and average power of more than 1 W. A double cladding photonic crystal fiber was used to deliver the excitation beam and to collect the two-photon signal. The hand-held probe included galvanometer-based mirror scanners, relay lenses and a focusing lens. The packaged probe had a diameter of 16 mm. Second harmonic generation (SHG) images and two-photon excited fluorescence (TPEF) images of biological tissues were demonstrated using the system. PMID:20635426

  17. Photophysical characterization of sickle cell disease hemoglobin by multi-photon microscopy.

    PubMed

    Vigil, Genevieve D; Howard, Scott S

    2015-10-01

    The photophysical properties of human sickle cell disease (SCD) Hemoglobin (Hb) is characterized by multi-photon microscopy (MPM). The intrinsic two-photon excited fluorescence (TPEF) signal associated with extracted hemoglobin was investigated and the solidified SCD variant (HbS) was found to demonstrate broad emission peaking around 510 nm when excited at 800 nm. MPM is used to dynamically induce and image HbS gelling by photolysis of deoxygenated HbS. For comparison, photolysis conditions were applied to a healthy variant of human hemoglobin (HbA) and found to remain in solution not forming fibers. The use of this signal to study the mechanism of HbS polymerization associated with the sickling of SCD erythrocytes is discussed. PMID:26504657

  18. Photophysical characterization of sickle cell disease hemoglobin by multi-photon microscopy

    PubMed Central

    Vigil, Genevieve D.; Howard, Scott S.

    2015-01-01

    The photophysical properties of human sickle cell disease (SCD) Hemoglobin (Hb) is characterized by multi-photon microscopy (MPM). The intrinsic two-photon excited fluorescence (TPEF) signal associated with extracted hemoglobin was investigated and the solidified SCD variant (HbS) was found to demonstrate broad emission peaking around 510 nm when excited at 800 nm. MPM is used to dynamically induce and image HbS gelling by photolysis of deoxygenated HbS. For comparison, photolysis conditions were applied to a healthy variant of human hemoglobin (HbA) and found to remain in solution not forming fibers. The use of this signal to study the mechanism of HbS polymerization associated with the sickling of SCD erythrocytes is discussed. PMID:26504657

  19. Differentiation of normal and cancerous lung tissues by multiphoton imaging

    E-print Network

    Wang, Chun-Chin

    We utilize multiphoton microscopy for the label-free diagnosis of noncancerous, lung adenocarcinoma (LAC), and lung squamous cell carcinoma (SCC) tissues from humans. Our results show that the combination of second-harmonic ...

  20. Reassignment of Scattered Emission Photons in Multifocal Multiphoton Microscopy

    E-print Network

    Cha, Jae Won

    Multifocal multiphoton microscopy (MMM) achieves fast imaging by simultaneously scanning multiple foci across different regions of specimen. The use of imaging detectors in MMM, such as CCD or CMOS, results in degradation ...

  1. Extending imaging depth of multiphoton microscopy

    E-print Network

    Cha, Jae Won

    2007-01-01

    Two-photon excitation fluorescence microscopy has capability of deep tissue imaging with biological samples. However, because of the inhomogeneity of the refractive index in biological samples, the wavefront of the excitation ...

  2. Characterizing germania concentration and structure in fiber soot using multiphoton microscopy and spectroscopy technology

    NASA Astrophysics Data System (ADS)

    Chen, Minghan; Li, Ming-Jun; Liu, Anping

    2015-02-01

    Germania doping is commonly used in the core of optical fiber due to its advantages compared to other materials such as superior transparency in near-infrared telecommunication wavelength region. During fiber preform manufacturing using the outside vapor deposition (OVD) process, Ge is doped into a silica soot preform by chemical vapor deposition. Since the Ge doping concentration profile is directly correlated with the fiber refractive index profile, its characterization is critical for the fiber industry. Electron probe micro-analyzer (EPMA) is a conventional analysis method for characterizing the Ge concentration profile. However, it requires extensive sample preparation and lengthy measurement. In this paper, a multiphoton microscopy technique is utilized to measure the Ge doping profile based on the multiphoton fluorescence intensity of the soot layers. Two samples, one with ramped and another with stepped Ge doping profiles were prepared for measurements. Measured results show that the technique is capable of distinguishing ramped and stepped Ge doping profiles with good accuracy. In the ramped soot sample, a sharp increment of doping level was observed in about 2 mm range from soot edge followed by a relative slow gradient doping accretion. As for the stepped doping sample, step sizes ranging from around 1 mm (at soot edge) to 3 mm (at soot center) were observed. All the measured profiles are in close agreement with that of the EPMA measurements. In addition, both multiphoton fluorescence (around 420 nm) and sharp second harmonic generations (at 532 nm) were observed, which indicates the co-existence of crystal and amorphous GeO2.

  3. Generation of High-Order Squeezing in Multiphoton Micromaser

    NASA Technical Reports Server (NTRS)

    Li, Fu-Li; Huang, Qing

    1996-01-01

    The generation of steady state higher-order squeezing in the sense of Hong and Mandel and also of Hillery in a multiphoton micromaser is studied. The results show that the cotangent state which is generated by the coherent trapping scheme in a multiphoton micromaser can exhibit not only second-order squeezing but also fourth-order and squared field amplitude squeezings. The influence of the cavity loss on the squeezings is investigated.

  4. Photon statistics of atomic fluorescence after {pi}-pulse excitation

    SciTech Connect

    Yoshimi, Kazuyoshi; Koshino, Kazuki

    2010-09-15

    The photon statistics of atomic fluorescence after {pi}-pulse excitation is investigated in a system in which the input and output ports are connected to an atom. Since spontaneous decay during input pulse excitation occurs, the output pulse generally contains a multiphoton component with a certain probability. We quantitatively evaluate the probability of the output pulse containing multiple photons and determine the conditions for ideal single-photon generation.

  5. REVIEW ARTICLE Multiphoton polymerization of hybrid materials

    NASA Astrophysics Data System (ADS)

    Farsari, Maria; Vamvakaki, Maria; Chichkov, Boris N.

    2010-12-01

    Multiphoton polymerization has been developed as a direct laser writing technique for the preparation of complex 3D structures with resolution beyond the diffraction limit of light. The combination of two or more hybrid materials with different functionalities in the same system has allowed the preparation of structures with advanced properties and functions. Furthermore, the surface functionalization of the 3D structures opens new avenues for their applications in a variety of nanobiotechnological fields. This paper describes the principles of 2PP and the experimental set-up used for 3D structure fabrication. It also gives an overview of the materials that have been employed in 2PP so far and depicts the perspectives of this technique in the development of new active components.

  6. Intravital multiphoton microscopy for imaging hepatobiliary function

    NASA Astrophysics Data System (ADS)

    Li, Feng-Chieh; Sun, Tzu-Lin; Lee, Hsuan-Shu; Yang, Shu-Mei; Dong, Chen-Yuan

    2007-07-01

    Liver is the chemical factory in body responsible for important functions such as metabolism and detoxification. When liver can not be regenerated in time to amend damages that has occurred, failure of hepatic functions can result. Traditionally, the study of liver pathology has depended on histological techniques, but such methods are limited to ex-vivo observation. In order to study hepatic metabolism in vivo, we have designed a hepatic imaging chamber made of biocompatible titanium alloy (6V4Al-Ti, ELI grade). In combination with multiphoton and second harmonic generation microscopy, our approach allows the intravital observation of hepatic intravital activities to be achieved. Processes such as hepatic metabolism and disease progression can be studied using this methodology.

  7. Generalized multi-photon quantum interference

    E-print Network

    Max Tillmann; Si-Hui Tan; Sarah E. Stoeckl; Barry C. Sanders; Hubert de Guise; René Heilmann; Stefan Nolte; Alexander Szameit; Philip Walther

    2015-02-12

    Non-classical interference of photons lies at the heart of optical quantum information processing. This effect is exploited in universal quantum gates as well as in purpose-built quantum computers that solve the BosonSampling problem. Although non-classical interference is often associated with perfectly indistinguishable photons this only represents the degenerate case, hard to achieve under realistic experimental conditions. Here we exploit tunable distinguishability to reveal the full spectrum of multi-photon non-classical interference. This we investigate in theory and experiment by controlling the delay times of three photons injected into an integrated interferometric network. We derive the entire coincidence landscape and identify transition matrix immanants as ideally suited functions to describe the generalized case of input photons with arbitrary distinguishability. We introduce a compact description by utilizing a natural basis which decouples the input state from the interferometric network, thereby providing a useful tool for even larger photon numbers.

  8. Engineering multiphoton states for linear optics computation

    E-print Network

    Paolo Aniello; Cosmo Lupo; Mario Napolitano; Matteo G. A. Paris

    2006-05-31

    Transformations achievable by linear optical components allow to generate the whole unitary group only when restricted to the one-photon subspace of a multimode Fock space. In this paper, we address the more general problem of encoding quantum information by multiphoton states, and elaborating it via ancillary extensions, linear optical passive devices and photodetection. Our scheme stems in a natural way from the mathematical structures underlying the physics of linear optical passive devices. In particular, we analyze an economical procedure for mapping a fiducial 2-photon 2-mode state into an arbitrary 2-photon 2-mode state using ancillary resources and linear optical passive N-ports assisted by post-selection. We found that adding a single ancilla mode is enough to generate any desired target state. The effect of imperfect photodetection in post-selection is considered and a simple trade-off between success probability and fidelity is derived.

  9. Distinguishing between benign and malignant melanocytic nevi by in vivo multiphoton microscopy

    PubMed Central

    Balu, Mihaela; Kelly, Kristen M.; Zachary, Christopher B.; Harris, Ronald M.; Krasieva, Tatiana B.; König, Karsten; Durkin, Anthony J.; Tromberg, Bruce J.

    2014-01-01

    Monitoring of atypical nevi is an important step in early detection of melanoma, a clinical imperative in preventing the disease progression. Current standard diagnosis is based on biopsy and histopathological examination, a method that is invasive and highly dependent upon the physician’s experience. In this work, we employed a clinical multiphoton microscope to image in vivo and non-invasively melanocytic nevi at three different stages: common nevi without dysplastic changes, dysplastic nevi with structural and architectural atypia, and melanoma. We analyzed multiphoton microscopy (MPM) images corresponding to 15 lesions (5 in each group) both qualitatively and quantitatively. For the qualitative analysis, we identified the morphological features characteristic of each group. MPM images corresponding to dysplastic nevi and melanoma were compared with standard histopathology in order to determine correlations between tissue constituents and morphology and to evaluate whether standard histopathology criteria can be identified in the MPM images. Prominent qualitative correlations included the morphology of epidermal keratinocytes, the appearance of nests of nevus cells surrounded by collagen fibers, and the structure of the epidermal-dermal junction. For the quantitative analysis, we defined a numerical “multiphoton melanoma index (MMI)” based on 3D in vivo image analysis that scores signals derived from two-photon excited fluorescence, second harmonic generation, and melanocyte morphology features on a continuous 9-point scale. Indices corresponding to common nevi (0–1), dysplastic nevi (1–4) and melanoma (5–8) were significantly different (p<0.05), suggesting the potential of the method to distinguish between melanocytic nevi in vivo. PMID:24686168

  10. Nonlocal thermodynamic equilibrium effects in stratospheric HF by collisional energy transfer from electronically excited O2 and implications for infrared remote sensing

    NASA Technical Reports Server (NTRS)

    Kaye, Jack A.

    1989-01-01

    A possible nonlocal thermodynamic equilibrium (non-LTE) effect involving stratospheric HF arising from the direct photochemical excitation of vibrationally excited HF by collisional energy transfer from electronically excited O2 is presented. Although this non-LTE effect is smaller that one associated with the direct solar excitation of both HF(nv = 1) and HF(nv = 2), calculations show that inclusion of the mechanism into retrieval algorithms is necessary if correct daytime upper stratosphere HF profiles are to be inferred in future IR thermal emission measurements.

  11. Cell-based and in vivo spectral analysis of fluorescent proteins for multiphoton microscopy

    E-print Network

    Verkhusha, Vladislav V.

    using excitation light from femtosecond pulsed, near-infrared lasers has become the preferred method beyond green fluorescent protein to generate molecules ranging from blue to near-infrared variants pathogenesis, and therapy.1­3 These studies continue to provide new, unexpected insights into dynamics of cell

  12. High-resolution multiphoton optical tomography of tissues: an in vitro and in vivo study

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Schenke-Layland, Katja; Ehlers, Alexander; Dimitrow, Enrico; Kaatz, Martin; Elsner, Peter; Martin, Sven; König, Karsten

    2006-03-01

    Multiphoton optical tomography based on NIR (near-infrared) femtosecond laser pulses provides non-invasive optical sectioning of skin with high spatial intracellular resolution and high tissue penetration. The imaging system DermaInspect was used to perform this technology in clinical studies in vivo on patients with suspicious melanoma. Pigmented cell clusters based on non-linear luminescence were clearly distinguished from non-pigmented cells in the epidermis using the autofluorescence of endogenous fluorophores like NAD(P)H, flavins, keratin, elastin, collagen and melanin. Some of the investigated tissues showed differences in the structure of the epidermal layers and the presence of dendritic cells compared to normal skin. Multiphoton laser microscopy was used to visualize extracellular matrix (ECM) structures of native and tissueengineered heart valves. The quality of the resulting 3-D images allowed an exact differentiation between collagenous and elastic fibers. The analysis of heart valve tissues of patients with cardiomyopathy revealed a dramatic loss of its capability to generate SH (second harmonic), indicating a structural deformation of the collagenous fibers, which was virtually impossible to obtain by routine histological or immunohistological staining. These results indicate that NIR femtosecond laser scanning systems can be employed as novel non-invasive optical technology for 3-D resolved ECM component imaging and in vitro and in vivo tissue diagnosis.

  13. Photon-momentum transfer in multiphoton ionization and in time-resolved holography with photoelectrons

    NASA Astrophysics Data System (ADS)

    Chelkowski, Szczepan; Bandrauk, André D.; Corkum, Paul B.

    2015-11-01

    In most models and theoretical calculations describing multiphoton ionization by infrared light, the dipole approximation is used. This is equivalent to setting the very small photon momentum to zero. Using numerical solutions of the two-dimensional (2-D) time-dependent Schrödinger equation for one electron (H-like) systems, we show that, for linear polarization, the radiation pressure on photoelectrons is very sensitive to the details of the ionization mechanism. The directly ionized photoelectrons, those that never recollide with the parent ion, are driven in the direction of the laser photon momentum, whereas a fraction of slower photoelectrons are pushed in the opposite direction, leading to the counterintuitive shifts observed in recent experiments [Phys. Rev. Lett. 113, 243001 (2014), 10.1103/PhysRevLett.113.243001]. This complex response is due to the interplay between the Lorentz force and the Coulomb attraction from the ion. On average, however, the photoelectron momentum is in the direction of the photon momentum as in the case of circular polarization. The influence of the photon momentum is shown to be discernible in the holographic patterns of time-resolved atomic and molecular holography with photoelectrons, thus suggesting a new research subject in multiphoton ionization.

  14. Stepwise multiphoton activation fluorescence reveals a new method of melanin detection.

    PubMed

    Lai, Zhenhua; Kerimo, Josef; Mega, Yair; Dimarzio, Charles A

    2013-06-01

    The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching. PMID:23291783

  15. Stepwise multiphoton activation fluorescence reveals a new method of melanin detection

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Kerimo, Josef; Mega, Yair; DiMarzio, Charles A.

    2013-06-01

    The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching.

  16. Simultaneous excitation of multiple fluororophores with a compact femtosecond laser

    NASA Astrophysics Data System (ADS)

    Legros, Philippe; Choquet, Daniel; Gueguen, Stéphane; Mottay, Eric; Deguil, Nelly

    2006-02-01

    We report on a flexible multiphoton imaging system, suitable for simultaneous and efficient excitation of red (DsRed), yellow (YFP), green (GFP) and blue (DAPI) fluorophores. We used a simple, compact laser system, consisting of a 1 ?m high energy diode-pumped oscillator and a tunable wavelength extension using a photonics crystal fibre. The combination of a near IR excitation wavelength, high energy per pulse for efficient three photon excitation and spectral extension for GFP excitation allows for high flexibility.We present experimental results of simultaneous and efficient imaging fluorophores couples from the UV to the red (DAPI-RFP, GFP-RFP).

  17. Deep-tissue multiphoton fluorescence lifetime microscopy for intravital imaging of protein-protein interactions

    NASA Astrophysics Data System (ADS)

    Fruhwirth, G. O.; Matthews, D. R.; Brock, A.; Keppler, M.; Vojnovic, B.; Ng, T.; Ameer-Beg, S.

    2009-02-01

    Fluorescent lifetime imaging microscopy (FLIM) has proven to be a valuable tool in beating the Rayleigh criterion for light microscopy by measuring Förster resonance energy transfer (FRET) between two fluorophores. Applying multiphoton FLIM, we previously showed in a human breast cancer cell line that recycling of a membrane receptorgreen fluorescent protein fusion is enhanced concomitantly with the formation of a receptor:protein kinase C ? complex in the endosomal compartment. We have extended this established technique to probe direct protein-protein interactions also in vivo. Therefore, we used various expressible fluorescent tags fused to membrane receptor molecules in order to generate stable two-colour breast carcinoma cell lines via controlled retroviral infection. We used these cell lines for establishing a xenograft tumour model in immune-compromised Nude mice. Using this animal model in conjunction with scanning Ti:Sapphire laser-based two-photon excitation, we established deep-tissue multiphoton FLIM in vivo. For the first time, this novel technique enables us to directly assess donor fluorescence lifetime changes in vivo and we show the application of this method for intravital imaging of direct protein-protein interactions.

  18. Single-wavelength reflected confocal and multiphoton microscopy for tissue imaging

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Liang; Chou, Chen-Kuan; Lin, Ming-Gu; Chen, Yang-Fang; Jee, Shiou-Hwa; Tan, Hsin-Yuan; Tsai, Tsung-Hua; Kim, Ki-Hean; Kim, Daekeun; So, Peter T. C.; Lin, Sung-Jan; Dong, Chen-Yuan

    2009-09-01

    Both reflected confocal and multiphoton microscopy can have clinical diagnostic applications. The successful combination of both modalities in tissue imaging enables unique image contrast to be achieved, especially if a single laser excitation wavelength is used. We apply this approach for skin and corneal imaging using the 780-nm output of a femtosecond, titanium-sapphire laser. We find that the near-IR, reflected confocal (RC) signal is useful in characterizing refractive index varying boundaries in bovine cornea and porcine skin, while the multiphoton autofluorescence (MAF) and second-harmonic generation (SHG) intensities can be used to image cytoplasm and connective tissues (collagen), respectively. In addition, quantitative analysis shows that we are able to detect MAF from greater imaging depths than with the near-IR RC signal. Furthermore, by performing RC imaging at 488, 543, and 633 nm, we find that a longer wavelength leads to better image contrast for deeper imaging of the bovine cornea and porcine skin tissue. Finally, by varying power of the 780-nm source, we find that comparable RC image quality was achieved in the 2.7 to 10.7-mW range.

  19. Combined multiphoton microscopy and optical coherence tomography using a 12-fs broadband source

    NASA Astrophysics Data System (ADS)

    Tang, Shuo; Krasieva, Tatiana B.; Chen, Zhongping; Tromberg, Bruce J.

    2006-03-01

    A 12-fs broadband (100-nm) source is used to combine multiphoton microscopy (MPM) and optical coherence tomography (OCT) in a single platform. An ultrafast Ti:sapphire laser simultaneously provides short pulses necessary for efficient MPM excitation and the broad bandwidth required for high-resolution OCT. Using 0.3-µm microspheres and a 63×, 0.95 numerical aperture objective, we demonstrate that MPM and OCT channels are coregistered with lateral resolution of approximately 0.5 µm and axial resolution of approximately 1.5 µm. Preliminary studies of a 3-D organotypic epithelial tissue model show that multiphoton images of fluorescence and second harmonic signals are derived from cellular and extracellular matrix structures, respectively, while OCT images are generated from scattering interfaces due to tissue variations in refractive index. The combined MPM/OCT microscope is capable of providing simultaneous functional and structural information from cells and extracellular matrix and is potentially a powerful tool for studying biological processes in thick tissues.

  20. In vivo multi-photon nanosurgery on cortical neurons: focusing on network organization

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; O'Connor, R. P.; Jasaitis, A.; Masi, A.; Buffelli, M.; Pavone, F. S.

    2008-02-01

    Two-photon microscopy has been used to perform high spatial resolution imaging of spine plasticity in the intact neocortex of living mice. Multi-photon absorption has also been used as a tool for the selective disruption of cellular structures in living cells and simple organisms. In this work we exploit the spatial localization of multi-photon excitation to perform selective lesions on the neuronal processes of cortical neurons in living mice expressing fluorescent proteins. This methodology was applied to dissect single dendrites with sub-micrometric precision without causing any visible collateral damage to the surrounding neuronal structures. The spatial precision of this method was demonstrated by ablating individual dendritic spines, while sparing the adjacent spines and the structural integrity of the dendrite. The morphological consequences were then characterized with time lapse 3D two-photon imaging over a period of minutes to days after the procedure. Here we present the results of our systematic study of the morphological response of cortical pyramidal neurons to nanosurgical perturbations. Dendritic branches were followed after transecting distal segments, whilst the plasticity and remodeling of individual dendritic spines on a given branch was also followed after removing of a subset of spines.

  1. Evolution of the superposition of displaced number states with the two-atom multiphoton Jaynes-Cummings model: interference and entanglement

    E-print Network

    Faisal Aly Aly El-Orany

    2005-12-14

    In this paper we study the evolution of the two two-level atoms interacting with a single-mode quantized radiation field, namely, two-atom multiphoton Jaynes-Cummings model when the radiation field and atoms are initially prepared in the superpostion of displaced number states and excited atomic states, respectively. For this system we investigate the atomic inversion, Wigner function, phase distribution and entanglement.

  2. Fine tunable red-green upconversion luminescence from glass ceramic containing 5%Er{sup 3+}:NaYF{sub 4} nanocrystals under excitation of two near infrared femtosecond lasers

    SciTech Connect

    Shang, Xiaoying; Cheng, Wenjing; Zhou, Kan; Ma, Jing; Feng, Donghai; Zhang, Shian; Sun, Zhenrong; Jia, Tianqing; Chen, Ping; Qiu, Jianrong

    2014-08-14

    In this paper, we report fine tunable red-green upconversion luminescence of glass ceramic containing 5%Er{sup 3+}: NaYF{sub 4} nanocrystals excited simultaneously by two near infrared femtosecond lasers. When the glass ceramic was irradiated by 800?nm femtosecond laser, weak red emission centered at 670?nm was detected. Bright red light was observed when the fs laser wavelength was tuned to 1490?nm. However, when excited by the two fs lasers simultaneously, the sample emitted bright green light centered at 550?nm, while the red light kept the same intensity. The dependences of the red and the green light intensities on the two pump lasers are much different, which enables us to manipulate the color emission by adjusting the two pump laser intensities, respectively. We present a theoretical model of Er{sup 3+} ions interacting with two fs laser fields, and explain well the experimental results.

  3. Control of resonance enhanced multi-photon ionization photoelectron spectroscopy by phase-shaped femtosecond laser pulse

    SciTech Connect

    Zhang Shian; Lu Chenhui; Jia Tianqing; Sun Zhenrong; Qiu Jianrong

    2012-11-07

    In this paper, we theoretically demonstrate that the (2+1+1) resonance enhanced multi-photon ionization photoelectron spectroscopy in sodium atom can be effectively controlled by shaping femtosecond laser pulse with a {pi} phase step modulation in weak laser field, involving its total photoelectron energy, maximal photoelectron intensity, and spectroscopic bandwidth. Our results show that the total photoelectron energy can be suppressed but not enhanced, the maximal photoelectron intensity can be enhanced and also suppressed, and the photoelectron spectroscopy can be tremendously narrowed. These theoretical results can provide a feasible scheme to achieve the high-resolution photoelectron spectroscopy and study the excited state structure in atomic and molecular systems.

  4. Photofragmentation, state interaction, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization of HI

    SciTech Connect

    Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst

    2014-06-28

    Mass resolved resonance enhanced multiphoton ionization data for hydrogen iodide (HI), for two-photon resonance excitation to Rydberg and ion-pair states in the 69?600–72?400 cm{sup ?1} region were recorded and analyzed. Spectral perturbations due to homogeneous and heterogeneous interactions between Rydberg and ion-pair states, showing as deformations in line-positions, line-intensities, and line-widths, were focused on. Parameters relevant to photodissociation processes, state interaction strengths and spectroscopic parameters for deperturbed states were derived. Overall interaction and dynamical schemes to describe the observations are proposed.

  5. Intense Visible and Near-Infrared Upconversion Photoluminescence in Colloidal LiYF4:Er3+ Nanocrystals under Excitation at 1490 nm

    PubMed Central

    Chen, Guanying; Ohulchanskyy, Tymish Y.; Kachynski, Aliaksandr; Ågren, Hans; Prasad, Paras N.

    2012-01-01

    We report intense upconversion photoluminescence (PL) in colloidal LiYF4:Er3+ nanocrystals under excitation with telecom-wavelength at 1490 nm. The intensities of two- and three-photon anti-Stokes upconversion PL bands are higher than or comparable to that of the Stokes emission under excitation with low power density in the range of 5–120 W/cm2. The quantum yield of the upconversion PL was measured to be as high as ~1.2±0.1%, which is almost 4 times higher than the highest upconversion PL quantum yield reported up to date for lanthanide-doped nanocrystals in 100 nm sized hexagonal NaYF4:Yb3+20%, Er3+2% using excitation at ~980 nm. Power dependence study revealed that the intensities of all PL bands have linear dependence on the excitation power density, which was explained by saturation effects in the intermediate energy states. PMID:21557587

  6. Soliton dynamics in the multiphoton plasma regime

    PubMed Central

    Husko, Chad A.; Combrié, Sylvain; Colman, Pierre; Zheng, Jiangjun; De Rossi, Alfredo; Wong, Chee Wei

    2013-01-01

    Solitary waves have consistently captured the imagination of scientists, ranging from fundamental breakthroughs in spectroscopy and metrology enabled by supercontinuum light, to gap solitons for dispersionless slow-light, and discrete spatial solitons in lattices, amongst others. Recent progress in strong-field atomic physics include impressive demonstrations of attosecond pulses and high-harmonic generation via photoionization of free-electrons in gases at extreme intensities of 1014 W/cm2. Here we report the first phase-resolved observations of femtosecond optical solitons in a semiconductor microchip, with multiphoton ionization at picojoule energies and 1010 W/cm2 intensities. The dramatic nonlinearity leads to picojoule observations of free-electron-induced blue-shift at 1016 cm?3 carrier densities and self-chirped femtosecond soliton acceleration. Furthermore, we evidence the time-gated dynamics of soliton splitting on-chip, and the suppression of soliton recurrence due to fast free-electron dynamics. These observations in the highly dispersive slow-light media reveal a rich set of physics governing ultralow-power nonlinear photon-plasma dynamics.

  7. Simultaneous measurement of neural spike recordings and multi-photon calcium imaging in neuroblastoma cells.

    PubMed

    Kim, Suhwan; Jung, Unsang; Baek, Juyeong; Kang, Shinwon; Kim, Jeehyun

    2012-01-01

    This paper proposes the design and implementation of a micro-electrode array (MEA) for neuroblastoma cell culturing. It also explains the implementation of a multi-photon microscope (MPM) customized for neuroblastoma cell excitation and imaging under ambient light. Electrical signal and fluorescence images were simultaneously acquired from the neuroblastoma cells on the MEA. MPM calcium images of the cultured neuroblastoma cell on the MEA are presented and also the neural activity was acquired through the MEA recording. A calcium green-1 (CG-1) dextran conjugate of 10,000 D molecular weight was used in this experiment for calcium imaging. This study also evaluated the calcium oscillations and neural spike recording of neuroblastoma cells in an epileptic condition. Based on our observation of neural spikes in neuroblastoma cells with our proposed imaging modality, we report that neuroblastoma cells can be an important model for epileptic activity studies. PMID:23202210

  8. Relationship between the atomic inversion and Wigner function for multiphoton multimode Jaynes-Cummings model

    E-print Network

    Faisal Aly Aly El-Orany

    2007-08-19

    In this paper we consider multimode multiphoton Jaynes-Cummings model, which consists of a two-level atom, initially prepared in an excited atomic state, interacting with $N$ modes of electromagnetic field prepared in general pure quantum states. For this system we show that under certain conditions the evolution of the Wigner function at the phase space origin provides direct information on the corresponding atomic inversion. This relation is also valid even if the system includes Kerr-like nonlinearity, Stark shift effect, different types of the initial atomic state as well as moving atom. Furthermore, based on this fact we discuss for the single-mode case the possibility of detecting the atomic inversion by means of techniques similar to those used for Wigner function.

  9. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  10. Three dimensional multiphoton imaging of fresh and whole mount developing mouse mammary glands

    PubMed Central

    2013-01-01

    Background The applications of multiphoton microscopy for deep tissue imaging in basic and clinical research are ever increasing, supplementing confocal imaging of the surface layers of cells in tissue. However, imaging living tissue is made difficult by the light scattering properties of the tissue, and this is extraordinarily apparent in the mouse mammary gland which contains a stroma filled with fat cells surrounding the ductal epithelium. Whole mount mammary glands stained with Carmine Alum are easily archived for later reference and readily viewed using bright field microscopy to observe branching architecture of the ductal network. Here, we report on the advantages of multiphoton imaging of whole mount mammary glands. Chief among them is that optical sectioning of the terminal end bud (TEB) and ductal epithelium allows the appreciation of abnormalities in structure that are very difficult to ascertain using either bright field imaging of the stained gland or the conventional approach of hematoxylin and eosin staining of fixed and paraffin-embedded sections. A second advantage is the detail afforded by second harmonic generation (SHG) in which collagen fiber orientation and abundance can be observed. Methods GFP-mouse mammary glands were imaged live or after whole mount preparation using a Zeiss LSM510/META/NLO multiphoton microscope with the purpose of obtaining high resolution images with 3D content, and evaluating any structural alterations induced by whole mount preparation. We describe a simple means for using a commercial confocal/ multiphoton microscope equipped with a Ti-Sapphire laser to simultaneously image Carmine Alum fluorescence and collagen fiber networks by SHG with laser excitation set to 860 nm. Identical terminal end buds (TEBs) were compared before and after fixation, staining, and whole mount preparation and structure of collagen networks and TEB morphologies were determined. Flexibility in excitation and emission filters was explored using the META detector for spectral emission scanning. Backward scattered or reflected SHG (SHG-B) was detected using a conventional confocal detector with maximum aperture and forward scattered or transmitted SHG (SHG-F) detected using a non-descanned detector. Results We show here that the developing mammary gland is encased in a thin but dense layer of collagen fibers. Sparse collagen layers are also interspersed between stromal layers of fat cells surrounding TEBs. At the margins, TEBs approach the outer collagen layer but do not penetrate it. Abnormal mammary glands from an HAI-1 transgenic FVB mouse model were found to contain TEBs with abnormal pockets of cells forming extra lumens and zones of continuous lateral bud formation interspersed with sparse collagen fibers. Parameters influencing live imaging and imaging of fixed unstained and Carmine Alum stained whole mounts were evaluated. Artifacts induced by light scattering of GFP and Carmine Alum signals from epithelial cells were identified in live tissue as primarily due to fat cells and in whole mount tissue as due to dense Carmine Alum staining of epithelium. Carmine Alum autofluorescence was detected at excitation wavelengths from 750 to 950 nm with a peak of emission at 623 nm (~602-656 nm). Images of Carmine Alum fluorescence differed dramatically at emission wavelengths of 565–615 nm versus 650–710 nm. In the latter, a mostly epithelial (nuclear) visualization of Carmine Alum predominates. Autofluorescence with a peak emission of 495 nm was derived from the fixed and processed tissue itself as it was present in the unstained whole mount. Contribution of autofluorescence to the image decreases with increasing laser excitation wavelengths. SHG-B versus SHG-F signals revealed collagen fibers and could be found within single fibers, or in different fibers within the same layer. These differences presumably reflected different states of collagen fiber maturation. Loss of SHG signals from layer to layer could be ascribed to artifacts rendered by light scat

  11. Hypericin-Mediated Destruction of Collagen Fibers Revealed by Multiphoton Microscopy

    NASA Astrophysics Data System (ADS)

    Hovhannisyan, Ararat Zh.; Hovhannisyan, Vladimir A.; Dong, Chen-Yuan

    Collagen is the major component of the extracellular matrix in skin, tendon, cartilage, cornea, bone, etc., and as a main structural protein is the key determinant of mechanical and functional properties of tissues and organs. Proper balance between synthesis and degradation of collagen fibers is critical for maintaining normal physiologic function; therefore, the modification of collagen fibers in a controlled manner is of high importance for biomedicine. In this work, using second harmonic generation (SHG) and two-photon excited auto-fluorescence (TPEF) microscopy, we revealed that hypericin, a natural pigment extracted from plant, induced structural modification of collagen based tissues. Dynamics of the process was monitored by time-lapse multiphoton imaging. It was demonstrated that hypericin-mediated process was considerably irreversible and has a potential to be used for destroying of abnormal tissues and treatment of some diseases.

  12. Multiphoton fluorescence spectra and lifetimes of biliverdins and their protein-associated complex

    NASA Astrophysics Data System (ADS)

    Huang, Chin-Jie; Wu, Cheng-Ham; Liu, Tzu-Ming

    2012-03-01

    To investigate whether endogenous biliverdins can serve as a fluorescence metabolic marker in cancer diagnosis, we measured their multiphoton fluorescence spectra and lifetimes with femtosecond Cr:forsterite laser. Excited at 1230nm, the two-photon fluorescence of biliverdins peaks around 670nm. The corresponding lifetime (<100ps) was much shorter than those of porphyrins (~10ns), which is another commonly present metabolites in living cells. Further mixing biliverdins with proteins like fetal bovine serum (FBS), biliverdins reductase A (BVRA), or heme oxygenase-1 (HO-1), the yields of red autofluorescences didn't change a lot, but the corresponding lifetimes with HO-1 and BSA were lengthened to 200~300ps. This indicates that biliverdin can have an association with these proteins and change its lifetime. These spectral and temporal characteristics of fluorescence make biliverdin a potential marker fluorophore for hyperspectral diagnosis on the heme catabolism in human cells or tissues.

  13. Simultaneous Measurement of Neural Spike Recordings and Multi-Photon Calcium Imaging in Neuroblastoma Cells

    PubMed Central

    Kim, Suhwan; Jung, Unsang; Baek, Juyeong; Kang, Shinwon; Kim, Jeehyun

    2012-01-01

    This paper proposes the design and implementation of a micro-electrode array (MEA) for neuroblastoma cell culturing. It also explains the implementation of a multi-photon microscope (MPM) customized for neuroblastoma cell excitation and imaging under ambient light. Electrical signal and fluorescence images were simultaneously acquired from the neuroblastoma cells on the MEA. MPM calcium images of the cultured neuroblastoma cell on the MEA are presented and also the neural activity was acquired through the MEA recording. A calcium green-1 (CG-1) dextran conjugate of 10,000 D molecular weight was used in this experiment for calcium imaging. This study also evaluated the calcium oscillations and neural spike recording of neuroblastoma cells in an epileptic condition. Based on our observation of neural spikes in neuroblastoma cells with our proposed imaging modality, we report that neuroblastoma cells can be an important model for epileptic activity studies. PMID:23202210

  14. Evaluation of multiphoton effects in down-conversion

    SciTech Connect

    Yoshimi, Kazuyoshi; Koshino, Kazuki

    2010-04-15

    Multiphoton effects in down-conversion are investigated based on the full-quantum multimode formalism by considering a three-level system as a prototype nonlinear system. We analytically derive the three-photon output wave function for two input photons, where one of the two input photons is down-converted and the other one is not. Using this output wave function, we calculate the down-conversion probability, the purity, and the fidelity to evaluate the entanglement between a down-converted photon pair and a non-down-converted photon. It is shown that the saturation effect occurs by multiphoton input and that it affects both the down-conversion probability and the quantum correlation between the down-converted photon pair and the non-down-converted photon. We also reveal the necessary conditions for multiphoton effects to be strong.

  15. Observation of detection-dependent multi-photon coherence times

    E-print Network

    Young-Sik Ra; Malte C. Tichy; Hyang-Tag Lim; Osung Kwon; Florian Mintert; Andreas Buchleitner; Yoon-Ho Kim

    2015-01-12

    The coherence time constitutes one of the most critical parameters that determines whether or not interference is observed in an experiment. For photons, it is traditionally determined by the effective spectral bandwidth of the photon. Here we report on multi-photon interference experiments in which the multi-photon coherence time, defined by the width of the interference signal, depends on the number of interfering photons and on the measurement scheme chosen to detect the particles. A theoretical analysis reveals that all multi-photon interference with more than two particles features this dependence, which can be attributed to higher-order effects in the mutual indistinguishability of the particles. As a striking consequence, a single, well-defined many-particle quantum state can exhibit qualitatively different degrees of interference, depending on the chosen observable. Therefore, optimal sensitivity in many-particle quantum interferometry can only be achieved by choosing a suitable detection scheme.

  16. Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

    NASA Astrophysics Data System (ADS)

    Lehmann, C. Stefan; Ram, N. Bhargava; Powis, Ivan; Janssen, Maurice H. M.

    2013-12-01

    Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations. Qualitative agreement is observed between the experimental results and the theoretical calculations of the Legendre moments representing the angular distribution for the two enantiomers. The electron-ion coincidence technique using multiphoton ionization opens new directions in table-top analytical mass-spectrometric applications of mixtures of chiral molecules.

  17. Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

    SciTech Connect

    Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M.; Powis, Ivan

    2013-12-21

    Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations. Qualitative agreement is observed between the experimental results and the theoretical calculations of the Legendre moments representing the angular distribution for the two enantiomers. The electron-ion coincidence technique using multiphoton ionization opens new directions in table-top analytical mass-spectrometric applications of mixtures of chiral molecules.

  18. Effect of multiphoton ionization on performance of crystalline lens.

    PubMed

    Gupta, Pradeep Kumar; Singh, Ram Kishor; Strickland, D; Campbell, M C W; Sharma, R P

    2014-12-15

    This Letter presents a model for propagation of a laser pulse in a human crystalline lens. The model contains a transverse beam diffraction effect, laser-induced optical breakdown for the creation of plasma via a multiphoton ionization process, and the gradient index (GRIN) structure. Plasma introduces the nonlinearity in the crystalline lens which affects the propagation of the beam. The multiphoton ionization process generates plasma that changes the refractive index and hence leads to the defocusing of the laser beam. The Letter also points out the relevance of the present investigation to cavitation bubble formation for restoring the elasticity of the eyes. PMID:25502994

  19. Nonlinear optical imaging characteristics of colonic adenocarcinoma using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Nenrong; Chen, Rong; Li, Hongsheng; Chen, Jianxin

    2012-12-01

    Multiphoton microscopy (MPM), a noninvasive optical method with high resolution and high sensitivity, can obtain detailed microstructures of biotissues at submolecular level. In this study, MPM is used to image microstructure varieties of human colonic mucosa and submucosa with adenocarcinoma. Some parameters, such as gland configuration, SHG/TPEF intensity ratio, and collagen orientation and so on, should serve the indicators of early colorectal cancer. The exploratory results show that it's potential for the development of multiphoton mini-endoscopy in real-time early diagnosis of colorectal cancer.

  20. Multiphoton autofluorescence spectral analysis for fungus imaging and identification

    NASA Astrophysics Data System (ADS)

    Lin, Sung-Jan; Tan, Hsin-Yuan; Kuo, Chien-Jui; Wu, Ruei-Jr; Wang, Shiou-Han; Chen, Wei-Liang; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2009-07-01

    We performed multiphoton imaging on fungi of medical significance. Fungal hyphae and spores of Aspergillus flavus, Micosporum gypseum, Micosoprum canis, Trichophyton rubrum, and Trichophyton tonsurans were found to be strongly autofluorescent but generate less prominent second harmonic signal. The cell wall and septum of fungal hyphae can be easily identified by autofluorescence imaging. We found that fungi of various species have distinct autofluorescence characteristics. Our result shows that the combination of multiphoton imaging and spectral analysis can be used to visualize and identify fungal species. This approach may be developed into an effective diagnostic tool for fungal identification.

  1. Multi-photon entanglement in high dimensions

    E-print Network

    Mehul Malik; Manuel Erhard; Marcus Huber; Mario Krenn; Robert Fickler; Anton Zeilinger

    2015-09-08

    Entanglement lies at the heart of quantum mechanics $-$ as a fundamental tool for testing its deep rift with classical physics, while also providing a key resource for quantum technologies such as quantum computation and cryptography. In 1987 Greenberger, Horne, and Zeilinger realized that the entanglement of more than two particles implies a non-statistical conflict between local realism and quantum mechanics. The resulting predictions were experimentally confirmed by entangling three photons in their polarization. Experimental efforts since have singularly focused on increasing the number of particles entangled, while remaining in a two-dimensional space for each particle. Here we show the experimental generation of the first multi-photon entangled state where both $-$ the number of particles and the number of dimensions $-$ are greater than two. Interestingly, our state exhibits an asymmetric entanglement structure that is only possible when one considers multi-particle entangled states in high dimensions. Two photons in our state reside in a three-dimensional space, while the third lives in two dimensions. Our method relies on combining two pairs of photons, high-dimensionally entangled in their orbital angular momentum, in such a way that information about their origin is erased. Additionally, we show how this state enables a new type of "layered" quantum cryptographic protocol where two parties share an additional layer of secure information over that already shared by all three parties. In addition to their application in novel quantum communication protocols, such asymmetric entangled states serve as a manifestation of the complex dance of correlations that can exist within quantum mechanics.

  2. Multiphoton Coherent Manipulation in Large Spin Qubits

    NASA Astrophysics Data System (ADS)

    Chiorescu, Irinel

    2009-03-01

    Manipulation of quantum information allows certain algorithms to be performed at unparalleled speeds. Photons are an ideal choice to manipulate qubits as they interact with quantum systems in predictable ways. They are a versatile tool for manipulating, reading/coupling qubits and for encoding/transferring quantum information over long distances. Spin-based qubits have well known behavior under photon driving and can be potentially operated up to room temperature. When diluted enough to avoid uncontrolled spin-spin interactions, a variety of spin qubits show long coherence times, e.g. the nitrogen vacancies in pure diamonds (1,2), nitrogen atoms trapped in a C60 cage (3), Ho3+ and Cr5+ ions (4,5) and molecular magnets (6,7). We have used large spin Mn2+ ions (S=5/2) to realize a six level system that can be operated by means of single as well as multi-photon coherent Rabi oscillations (8). This spin system has a very small anisotropy whose effect can be tuned in-situ to turn the system into a multi-level harmonic system. This offer new ways of manipulating, reading and resetting a spin qubit. Decoherence effects are strongly reduced by the quasi-isotropic electron interaction with the crystal field and with the 55Mn nuclear spins. [0pt] 1. R. Hanson et al., Science 320, 352 (2008). [0pt] 2. M.V. Gurudev Dutt et al., Science 316, 1312 (2007). [0pt] 3. G.W. Morley et al., Phys. Rev. Lett. 98, 220501 (2007). [0pt] 4. S. Bertaina et al., Nat. Nanotech. 2, 39 (2007). [0pt] 5. S. Nellutla et al., Phys. Rev. Lett. 99, 137601 (2007). [0pt] 6. A. Ardavan et al., Phys. Rev. Lett. 98, 057201 (2007). [0pt] 7. S. Bertaina et al., Nature 453, 203,(2008). [0pt] 8. S. Bertaina et al., submitted.

  3. Origin and effect of high-order dispersion in ultrashort pulse multiphoton microscopy in the 10 fs regime.

    PubMed

    Wang, Weichao; Liu, Yujia; Xi, Peng; Ren, Qiushi

    2010-12-10

    Short pulses can induce high nonlinear excitation, and thus they should be favorable for use in multiphoton microscopy. However, the large spectral dispersion can easily destroy the advantages of the ultrashort pulse if there is no compensation. The group delay dispersion (GDD), third-order dispersion, and their effects on the intensity and bandwidth of second-harmonic generation (SHG) signal were analyzed. We found that the prism pair used for compensating the GDD of the two-photon microscope actually introduces significant negative high-order dispersion (HOD), which dramatically narrowed down the two-photon absorption probability for ultrashort pulses. We also investigated the SHG signal after GDD and HOD compensation for different pulse durations. Without HOD compensation, the SHG efficiency dropped significantly for a pulse duration below 20 fs. We experimentally compared the SHG and two-photon excited fluorescence (TPEF) signal intensity for 11 fs versus 50 fs pulses, a pulse duration close to that commonly used in conventional multiphoton microscopy. The result suggested that after adaptive phase compensation, the 11fs pulse can yield a 3.2- to 6.0-fold TPEF intensity and a 5.1-fold SHG intensity, compared to 50 fs pulses. PMID:21151226

  4. Optical depletion mechanism of upconverting luminescence and its potential for multi-photon STED-like microscopy.

    PubMed

    Wu, Ruitao; Zhan, Qiuqiang; Liu, Haichun; Wen, Xuanyuan; Wang, Baoju; He, Sailing

    2015-12-14

    Simulated emission depletion (STED) microscopy is very powerful, but still suffers from small tissue penetration depth, photobleaching of fluorescent probes and complicated imaging systems. Here, we propose an optical luminescence depletion mechanism employing upconverting nanoparticles (UCNPs) and explore its potential for multi-photon STED-like microscopy. With the addition of Yb3+ ions in NaYF4:Er3+ UCNPs, the two-photon green emission of Er3+ under 795-nm excitation was successfully depleted by 1140-nm laser through the synergetic effect of the excited state absorption and the interionic energy transfer. This STED-like depletion mechanism was systematically investigated using steady-state rate equations, evidenced by the surprising emerging of 478-nm emission. The green emission depletion efficiency was about 30%, limited by the current laser source. Our work indicates that NaYF4:Yb3+/Er3+ UCNPs will be potential probes for multi-photon super-resolution microscopy with many advantages, including long-wavelength-induced large penetration, non-photobleaching and non-photoblinking properties, cost-effective and simplified imaging systems. PMID:26699029

  5. Isomerization and dissociation dynamics of HCN in a picosecond infrared laser field: A full-dimensional classical study

    SciTech Connect

    Gong Jiangbin; Ma Ao; Rice, Stuart A.

    2005-04-08

    We report a full-dimensional study of the classical dynamics of HCN{yields}HNC isomerization and of HCN rovibrational dissociation driven by a strong but nonionizing picosecond infrared laser field. The dynamics of the isolated molecule and of the molecule in liquid Ar have both been studied. Our theoretical and numerical results show that when all degrees of freedom are accounted for the field induced molecular dynamics can be totally different from what was found in previous studies, where the HCN molecule is restricted to a plane containing the external field. It is shown that as HCN is driven by an infrared laser field, the rotation of the H atom around the C-N bond provides an important and highly efficient energy absorption mechanism. In the presence of a monochromatic picosecond infrared laser field with an intensity of 10{sup 13} W/cm{sup 2}, this energy absorption mechanism generates considerable HCN{yields}HNC isomerization yield or high rovibrational dissociation yield without molecular preorientation or prealignment. Our study of the field induced isomerization and dissociation dynamics of the same system in liquid Ar shows that the picosecond isomerization dynamics is insignificantly affected by the surrounding atomic liquid whereas the dissociation yield may be greatly suppressed in a high density liquid. The implications of this study for full-dimensional quantum dynamics of multiphoton rovibrational excitation and dissociation of triatomics are briefly discussed.

  6. Multi-photon Absorption in Optical Pumping of Rubidium

    E-print Network

    Xu, Xinyi

    2015-01-01

    In optical pumping of rubidium, a new kind of absorption occurs with a higher amplitude of radio frequency current. From measurement of the corresponding magnetic field value where this absorption occurs, there is a conclusion that it is multi-photon absorption. Both the degeneracy and energy of photons contribute to the intensity.

  7. Generalized parity in multi-photon Rabi model

    E-print Network

    Bart?omiej Gardas; Jerzy Dajka

    2013-01-16

    Quantum multi--photon spin--boson model is considered. We solve an operator Riccati equation associated with that model and present a candidate for a generalized parity operator allowing to transform spin--boson Hamiltonian to a block diagonal form what indicates an existence of the related symmetry of the model.

  8. Single-beam homodyne SPIDER for multiphoton microscopy

    E-print Network

    Lim, Sang-Hyun

    Single-beam homodyne SPIDER for multiphoton microscopy Jiha Sung, Bi-Chang Chen, and Sang-Hyun Lim a new version of spectral phase interferometry for direct electric field reconstruction (SPIDER for SPIDER (HOT SPIDER). An arbitrary spectral phase at the sample position of a microscope can

  9. Exploring the molecular chemistry and excitation in obscured luminous infrared galaxies: An ALMA mm-wave spectral scan of NGC 4418

    E-print Network

    Costagliola, F; Muller, S; Martín, S; Aalto, S; Harada, N; van der Werf, P; Viti, S; Garcia-Burillo, S; Spaans, M

    2015-01-01

    We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418, spanning a total of 70.7 GHz in bands 3, 6, and 7. We use a combined local thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to identify the molecular species and derive column densities and excitation temperatures. We derive molecular abundances and compare them with other Galactic and extragalactic sources by means of a principal component analysis. We detect 317 emission lines from a total of 45 molecular species, including 15 isotopic substitutions and six vibrationally excited variants. Our LTE/NLTE fit find kinetic temperatures from 20 to 350 K, and densities between 10$^5$ and 10$^7$ cm$^{-3}$. The spectrum is dominated by vibrationally excited HC$_3$N, HCN, and HNC, with vibrational temperatures from 300 to 450 K. We find high abundances of HC$_3$N, SiO, H$_2$S, and c-HCCCH and a low CH$_3$OH abundance. A principal component analysis shows that NGC 4418 and Arp 220 share very similar molecular abundances and ...

  10. Multi-photon ionization of atoms in intense short-wavelength radiation fields

    NASA Astrophysics Data System (ADS)

    Meyer, Michael

    2015-05-01

    The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing the intensity dependent variation of the angular distribution patterns for the sequential ionization process.

  11. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    SciTech Connect

    Marcos Dantus

    2008-09-23

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10^16 W/cm^2. In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  12. Multiphoton microscopy of endogenous fluorescence differentiates normal, precancerous, and cancerous squamous epithelial tissues.

    PubMed

    Skala, Melissa C; Squirrell, Jayne M; Vrotsos, Kristin M; Eickhoff, Jens C; Gendron-Fitzpatrick, Annette; Eliceiri, Kevin W; Ramanujam, Nirmala

    2005-02-15

    This study characterizes the morphologic features and the endogenous fluorescence in the stratified squamous epithelia of the 7,12-dimethylbenz(a)anthracene-treated hamster cheek pouch model of carcinogenesis using multiphoton laser scanning microscopy (MPLSM). MPLSM allows high-resolution, three-dimensional image data to be collected deeper within thick tissue samples with reduced phototoxicity compared with single-photon imaging. Three-dimensional image stacks of normal (n = 13), precancerous (dysplasia, n = 12; carcinoma in situ, n = 9) and cancerous tissue [nonpapillary squamous cell carcinoma (SCC), n = 10, and papillary SCC, n = 7] sites in the hamster cheek pouch were collected in viable, unsectioned tissue biopsies at a two-photon excitation wavelength of 780 nm. Five features were quantified from the MPLSM images. These included nuclear density versus depth, keratin layer thickness, epithelial thickness, and the fluorescence per voxel in the keratin and epithelial layers. Statistically significant differences in all five features were found between normal and both precancerous and cancerous tissues. The only exception to this was a lack of statistically significant differences in the keratin fluorescence between normal tissues and papillary SCCs. Statistically significant differences were also observed in the epithelial thickness of dysplasia and carcinoma in situ, and in the keratin layer thickness of dysplasia and SCCs (both nonpapillary and papillary). This work clearly shows that three-dimensional images from MPLSM of endogenous tissue fluorescence can effectively distinguish between normal, precancerous, and cancerous epithelial tissues. This study provides the groundwork for further exploration into the application of multiphoton fluorescence endoscopy in a clinical setting. PMID:15735001

  13. The near-infrared structure and spectra of the bipolar nebulae M2-9 and AFGL 2688: The role of ultraviolet pumping and shocks in molecular hydrogen excitation

    NASA Technical Reports Server (NTRS)

    Hora, Joseph L.; Latter, William B.

    1994-01-01

    High-resolution near-infrared images and moderate resolution spectra were obtained of the bipolar nebulae M2-9 and AFGL 2688. The ability to spatially and spectrally resolve the various components of the nebulae has proved to be important in determining their physical structure and characteristics. In M2-9, the lobes are found to have a double-shell structure. The inner shell is dominated by emission from hydrogen recombination lines, and the outer shell is primarily emission from H2 lines in teh 2-2.5 micron region. Analysis of H2 line ratios indicates that the H2 emission is radiatively excited. A well-resolved photodissociation region is observed in the lobes. The spectrum of the central source is dominated by H recombination lines and a strong continuum rising toward longer wavelengths consistent with a T = 795 K blackbody. Also present are lines of He I and Fe II. In contrast, the N knot and E lobe of M2-9 show little continuum emission. The N knot spectrum consists of lines of (Fe II) and hydrogen recombination lines. In AGFL 2688, the emission from the bright lobes is mainly continuum reflected from the central star. Several molecular features from C2 and CN are present. In the extreme end of the N lobe and in the E equatorial region, the emission is dominated by lines of H2 in the 2-2.5 region. The observed H2 line ratios indicate that the emission is collisionally excited, with an excitation temperature T(sub ex) approixmately = 1600 +/- 100 K.

  14. Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube

    PubMed Central

    Cha, Jae Won; Yew, Elijah Y. S.; Kim, Daekeun; Subramanian, Jaichandar; Nedivi, Elly; So, Peter T. C.

    2015-01-01

    Multifocal multiphoton microscopy (MMM) improves imaging speed over a point scanning approach by parallelizing the excitation process. Early versions of MMM relied on imaging detectors to record emission signals from multiple foci simultaneously. For many turbid biological specimens, the scattering of emission photons results in blurred images and degrades the signal-to-noise ratio (SNR). We have recently demonstrated that a multianode photomultiplier tube (MAPMT) placed in a descanned configuration can effectively collect scattered emission photons from each focus into their corresponding anodes significantly improving image SNR for highly scattering specimens. Unfortunately, a descanned MMM has a longer detection path resulting in substantial emission photon loss. Optical design constraints in a descanned geometry further results in significant optical aberrations especially for large field-of-view (FOV), high NA objectives. Here, we introduce a non-descanned MMM based on MAPMT that substantially overcomes most of these drawbacks. We show that we improve signal efficiency up to fourfold with limited image SNR degradation due to scattered emission photons. The excitation foci can also be spaced wider to cover the full FOV of the objective with minimal aberrations. The performance of this system is demonstrated by imaging interneuron morphological structures deep in the brains of living mice. PMID:25874160

  15. Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube

    NASA Astrophysics Data System (ADS)

    Cha, Jae Won; Yew, Elijah Y. S.; Kim, Daekeun; Subramanian, Jaichandar; Nedivi, Elly; So, Peter T. C.

    2015-08-01

    Multifocal multiphoton microscopy (MMM) improves imaging speed over a point scanning approach by parallelizing the excitation process. Early versions of MMM relied on imaging detectors to record emission signals from multiple foci simultaneously. For many turbid biological specimens, the scattering of emission photons results in blurred images and degrades the signal-to-noise ratio (SNR). We have recently demonstrated that a multianode photomultiplier tube (MAPMT) placed in a descanned configuration can effectively collect scattered emission photons from each focus into their corresponding anodes significantly improving image SNR for highly scattering specimens. Unfortunately, a descanned MMM has a longer detection path resulting in substantial emission photon loss. Optical design constraints in a descanned geometry further results in significant optical aberrations especially for large field-of-view (FOV), high NA objectives. Here, we introduce a non-descanned MMM based on MAPMT that substantially overcomes most of these drawbacks. We show that we improve signal efficiency up to fourfold with limited image SNR degradation due to scattered emission photons. The excitation foci can also be spaced wider to cover the full FOV of the objective with minimal aberrations. The performance of this system is demonstrated by imaging interneuron morphological structures deep in the brains of living mice.

  16. Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

    NASA Astrophysics Data System (ADS)

    Huang, H.; Shi, H.; Feng, S.; Lin, J.; Chen, W.; Huang, Z.; Li, Y.; Yu, Y.; Lin, D.; Xu, Q.; Chen, R.

    2013-04-01

    This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites.

  17. Further observations of rotationally excited far infrared OH16 and OH18 emission in Orion-KL: Tighter constraints on the nature of the emitting region

    NASA Technical Reports Server (NTRS)

    Melnick, G. J.; Stacey, G. J.; Genzel, R.; Lugten, J. B.; Poglitsch, A.

    1989-01-01

    The Orion-KL region, within 1 arc minute, is observed. The rotational cross ladder (53.351 microns) and rotational ground state (120.1719 microns) transitions are studied. It is shown that these lines exhibit a P-Cygni profile and unambiguously show that the OH gas is expanding out from the central BN-KL infrared cluster. The OH-16 rotational ground state transition (119.234 microns) is velocity resolved and it is found that its intrinsic full width at half maximum is 75 km/s. The line fluxes and line profiles are modeled and it is shown that no single temperature and density component can reproduce the data. Rather, the best fit to the data requires emission from three main components of the gas: post shocked gas with the profiles of temperature, density, and OH abundance; a high density component to the cool post shocked region; and the plateau region.

  18. Herschel Far-infrared Spectral-mapping of Orion BN/KL Outflows: Spatial Distribution of Excited CO, H2O, OH, O, and C+ in Shocked Gas

    NASA Astrophysics Data System (ADS)

    Goicoechea, Javier R.; Chavarría, Luis; Cernicharo, José; Neufeld, David A.; Vavrek, Roland; Bergin, Edwin A.; Cuadrado, Sara; Encrenaz, Pierre; Etxaluze, Mireya; Melnick, Gary J.; Polehampton, Edward

    2015-01-01

    We present ~2' × 2' spectral-maps of Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) outflows taken with Herschel at ~12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H2 shocked regions "Peak 1" and "Peak 2" from that of the hot core and ambient cloud. We analyze the ~54-310 ?m spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of 12CO (up to J = 48-47), H2O, OH, 13CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L FIR ? 5 × 10-3 ratio and a plethora of far-IR H2O emission lines. The high-J CO and OH lines are a factor of ?2 brighter toward Peak 1 whereas several excited H2O lines are lsim50% brighter toward Peak 2. Most of the CO column density arises from T k ~ 200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H2O/CO lsim 10-2 abundance ratio. In addition, the very excited CO (J > 35) and H2O lines reveal a hotter gas component (T k ~ 2500 K) from faster (v S > 25 km s-1) shocks that are able to sputter the frozen-out H2O and lead to high H2O/CO gsim 1 abundance ratios. The H2O and OH luminosities cannot be reproduced by shock models that assume high (undepleted) abundances of atomic oxygen in the preshock gas and/or neglect the presence of UV radiation in the postshock gas. Although massive outflows are a common feature in other massive star-forming cores, Orion BN/KL seems more peculiar because of its higher molecular luminosities and strong outflows caused by a recent explosive event. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  19. Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Tung, Oi-Hong; Lee, Shyh-Yuan; Lai, Yu-Lin; Chen, How-Foo

    2011-06-01

    Subgingival calculus has been recognized as a major cause of periodontitis, which is one of the main chronic infectious diseases of oral cavities and a principal cause of tooth loss in humans. Bacteria deposited in subgingival calculus or plaque cause gingival inflammation, function deterioration, and then periodontitis. However, subgingival calculus within the periodontal pocket is a complicated and potentially delicate structure to be detected with current dental armamentaria, namely dental x-rays and dental probes. Consequently, complete removal of subgingival calculus remains a challenge to periodontal therapies. In this study, the detection of subgingival calculus employing a multiphoton autofluorescence imaging method was characterized in comparison with a one-photon confocal fluorescence imaging technique. Feasibility of such a system was studied based on fluorescence response of gingiva, healthy teeth, and calculus with and without gingiva covered. The multiphoton fluorescence technology perceived the tissue-covered subgingival calculus that cannot be observed by the one-photon confocal fluorescence method.

  20. Hybrid label-free multiphoton and optoacoustic microscopy (MPOM)

    NASA Astrophysics Data System (ADS)

    Soliman, Dominik; Tserevelakis, George J.; Omar, Murad; Ntziachristos, Vasilis

    2015-07-01

    Many biological applications require a simultaneous observation of different anatomical features. However, unless potentially harmful staining of the specimens is employed, individual microscopy techniques do generally not provide multi-contrast capabilities. We present a hybrid microscope integrating optoacoustic microscopy and multiphoton microscopy, including second-harmonic generation, into a single device. This combined multiphoton and optoacoustic microscope (MPOM) offers visualization of a broad range of structures by employing different contrast mechanisms and at the same time enables pure label-free imaging of biological systems. We investigate the relative performance of the two microscopy modalities and demonstrate their multi-contrast abilities through the label-free imaging of a zebrafish larva ex vivo, simultaneously visualizing muscles and pigments. This hybrid microscopy application bears great potential for developmental biology studies, enabling more comprehensive information to be obtained from biological specimens without the necessity of staining.

  1. Cryogenic exciter

    SciTech Connect

    Bray, James William; Garces, Luis Jose

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  2. Dark gamma-ray bursts: possible role of multiphoton processes

    E-print Network

    Mark E. Perel'man

    2009-07-27

    The absence of optical afterglow at some gamma-ray bursts (so called dark bursts) requires analyses of physical features of this phenomenon. It is shown that such singularity can be connected with multiphoton processes of frequencies summation in the Rayleigh- Jeans part of spectra, their pumping into higher frequencies. It can be registered most probably on young objects with still thin plasma coating, without further thermalization, i.e. soon after a prompt beginning of the explosive activity.

  3. Vectorizable wave propagation FORTRANcode for calculations of multiphoton dissociation

    NASA Astrophysics Data System (ADS)

    Ting, Julian J.-L.; Yuan, J. M.; Jiang, T.-F.

    1992-06-01

    A vectorizable FORTRAN code for the ETA10 or other vector machines for numerical calculation of the time-dependent Schrödinger equation is presented. Preliminary results for the multiphoton dissociation of nitrogen oxide are shown. The applied electric field was approximated by a classical sinusoidal wave; both sinusoidal and cosinusoidal wave forms were tested, and the internuclear potential was taken to be a Morse function. Dissociation histories of three types were found.

  4. Human hepatocellular carcinoma diagnosis by multiphoton autofluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Sun, Tzu-Lin; Liu, Yuan; Sung, Ming-Chin; Chen, Hsiao-Ching; Yang, Chuen-Huei; Hovhannisyan, Vladimir; Chiou, Ling-Ling; Lin, Wei-Chou; Huang, Guan-Tarn; Kim, Ki-Hean; So, Peter T. C.; Lin, Chih-Ju; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2010-02-01

    Conventionally, the diagnosis of hepatocellular carcinoma (HCC) is performed by qualitative examination of histopathological specimens, which takes times for sample preparation in fixation, section and stain. Our objective is to demonstrate an effective and efficient approach to apply multiphoton microscopy imaging the HCC specimens, with the advantages of being optical section, label-free, subcellular resolution, minimal invasiveness, and the acquisition of quantitative information at the same time. The imaging modality of multiphoton autofluorescence (MAF) was used for the qualitative imaging and quantitative analysis of HCC of different grades under ex-vivo, label-free conditions. We found that while MAF is effective in identifying cellular architecture in the liver specimens, and obtained quantitative parameters in characterizing the disease. Our results demonstrates the capability of using tissue quantitative parameters of multiphoton autofluorescence (MAF), the nuclear number density (NND), and nuclear-cytoplasmic ratio (NCR) for tumor discrimination and that this technology has the potential in clinical diagnosis of HCC and the in-vivo investigation of liver tumor development in animal models.

  5. Multiphoton ionization mass spectrometry of nitrated polycyclic aromatic hydrocarbons.

    PubMed

    Tang, Yuanyuan; Imasaka, Tomoko; Yamamoto, Shigekazu; Imasaka, Totaro

    2015-08-01

    In order to suppress the fragmentation and improve the sensitivity for determination of nitrated polycyclic aromatic hydrocarbons (NPAHs), the mechanism of multiphoton ionization was studied for the following representative NPAHs, 9-nitroanthracene, 3-nitrofluoranthene, and 1-nitropyrene. The analytes were extracted from the PM2.5 on the sampling filter ultrasonically, and were measured using gas chromatography/multiphoton ionization/time-of-flight mass spectrometry with a femtosecond tunable laser in the range from 267 to 405 nm. As a result, a molecular ion was observed as the major ion and fragmentation was suppressed at wavelengths longer than 345 nm. Furthermore, the detection limit measured at 345 nm was measured to be the subpicogram level. The organic compounds were extracted from a 2.19 mg sample of particulate matter 2.5 (PM2.5), and the extract was subjected to multiphoton ionization mass spectrometry after gas chromatograph separation. The background signals were drastically suppressed at 345 nm, and the target NPAHs, including 9-nitroanthracene and 1-nitropyrene, were detected, and their concentrations were determined to be 5 and 3 pg/m(3), respectively. PMID:26048831

  6. Multiphoton microscopy of engineered dermal substitutes: assessment of 3-D collagen matrix remodeling induced by fibroblast contraction.

    PubMed

    Pena, Ana-Maria; Fagot, Dominique; Olive, Christian; Michelet, Jean-François; Galey, Jean-Baptiste; Leroy, Frédéric; Beaurepaire, Emmanuel; Martin, Jean-Louis; Colonna, Anne; Schanne-Klein, Marie-Claire

    2010-01-01

    Dermal fibroblasts are responsible for the generation of mechanical forces within their surrounding extracellular matrix and can be potentially targeted by anti-aging ingredients. Investigation of the modulation of fibroblast contraction by these ingredients requires the implementation of three-dimensional in situ imaging methodologies. We use multiphoton microscopy to visualize unstained engineered dermal tissue by combining second-harmonic generation that reveals specifically fibrillar collagen and two-photon excited fluorescence from endogenous cellular chromophores. We study the fibroblast-induced reorganization of the collagen matrix and quantitatively evaluate the effect of Y-27632, a RhoA-kinase inhibitor, on dermal substitute contraction. We observe that collagen fibrils rearrange around fibroblasts with increasing density in control samples, whereas collagen fibrils show no remodeling in the samples containing the RhoA-kinase inhibitor. Moreover, we show that the inhibitory effects are reversible. Our study demonstrates the relevance of multiphoton microscopy to visualize three-dimensional remodeling of the extracellular matrix induced by fibroblast contraction or other processes. PMID:21054112

  7. Multiphoton and magnetic resonance imaging of Barley embryos: comparing micro-imaging techniques across scale and parameter barriers

    NASA Astrophysics Data System (ADS)

    Stark, Martin; Manz, Bertram; Riemann, Iris; Volke, Frank; Weschke, Winfriede; König, Karsten

    2007-02-01

    Multiphoton stimulated autofluorescence microscopy and Magnetic resonance imaging (MRI) address different molecular properties of the sample and reach to a different length scale. MRI maps density or mobility of nuclei (here: hydrogen), and targets at whole objects from the scale of sub-millimetres to meters. Multiphoton imaging profits from the nonlinear absorption of light in the focus of a femtosecond laser source stimulating the autofluorescence of biomolecules. As this effect relies on a high light intensity the accessible field of view is limited, but the resolution is very high. Studying a plant embryo (barley) we compare the two techniques. At 770 nm excitation the cell walls of the embryo exhibited significant autofluorescence, allowing for a subcellular resolution. While details where imaged with an objective of N.A. 1.3, an overview was generated with a N.A. as low as 0.25. The overview image as well as merged images and tomographical data were used to link the high-resolution optical data with the three-dimensional highresolution MR images. There, images of the proton density were acquired using a standard 3D spin-echo imaging pulse sequence. While the optical high-resolution data provides a field of view restricted to only a small part of the embryo, the MR image contains the whole grain. Bridging the scales it might be possible to trace transport of e.g. nutrients from large structure of the plant to the cellular level.

  8. Custom-made multiphoton microscope for long-term imaging of neuronal cultures to explore structural and functional plasticity

    NASA Astrophysics Data System (ADS)

    Rambani, Komal; Booth, Mark C.; Brown, Edgar A.; Raikov, Ivan; Potter, Steve M.

    2005-03-01

    We use dissociated cultures of E-18 rat cortical neurons to study how they process the information. To correlate electrophysiological data with corresponding network structure, we observe effects of the stimuli on structural changes in this culture using multiphoton microscopy. To keep our 2D and 3D cultures alive for long-term studies, it is necessary to protect them against photodamage. At the same time, we need a flexible microscope design to accommodate our multielectrode array (MEA) electrophysiological station. We have constructed a custom-designed multiphoton microscope based on design of Tsai et al. The microscope is optimized for two-photon imaging to collect maximum possible fluorescent signal using minimum excitation laser intensity. Special attention is paid to get uniformly illuminated images and the ability to use the entire bandwidth of the pulsed laser (700-1000 nm) with the same set of optical components. Flexibility of the design will allow us to easily change or incorporate other optical components suitable for different experimental needs. This microscope will allow us to do electrophysiology and imaging concurrently while maintaining the optimum temperature and CO2 levels.

  9. Near-Infrared Excited State Dynamics of Melanins: The Effects of Iron Content, Photo-Damage, Chemical Oxidation, and Aggregate Size

    PubMed Central

    2015-01-01

    Ultrafast pump–probe measurements can discriminate the two forms of melanin found in biological tissue (eumelanin and pheomelanin), which may be useful for diagnosing and grading melanoma. However, recent work has shown that bound iron content changes eumelanin’s pump–probe response, making it more similar to that of pheomelanin. Here we record the pump–probe response of these melanins at a wider range of wavelengths than previous work and show that with shorter pump wavelengths the response crosses over from being dominated by ground-state bleaching to being dominated by excited-state absorption. The crossover wavelength is different for each type of melanin. In our analysis, we found that the mechanism by which iron modifies eumelanin’s pump–probe response cannot be attributed to Raman resonances or differences in melanin aggregation and is more likely caused by iron acting to broaden the unit spectra of individual chromophores in the heterogeneous melanin aggregate. We analyze the dependence on optical intensity, finding that iron-loaded eumelanin undergoes irreversible changes to the pump–probe response after intense laser exposure. Simultaneously acquired fluorescence data suggest that the previously reported “activation” of eumelanin fluorescence may be caused in part by the dissociation of metal ions or the selective degradation of iron-containing melanin. PMID:24446774

  10. Corneal imaging and refractive index measurement using a combined multiphoton microscopy and optical coherence tomography system

    NASA Astrophysics Data System (ADS)

    Lai, Tom; Chong, Shau Poh; Zhou, Yifeng; Moloney, Gregory; Tang, Shuo

    2013-02-01

    Refractive index (RI) is the optical property of a medium that describes its ability to bend incident light. The corneal refractive index is an especially important measurement in corneal and intraocular refractive surgery where its precise estimation is necessary to obtain accurate surgical outcomes. In this study, we calculated the corneal RI using a combined multiphoton microscopy (MPM) and optical coherence tomography (OCT) system. MPM excites and detects nonlinear signals including two photon excitation fluorescence (TPEF) and second harmonic generation (SHG). TPEF signals are observed from NADH in the cytoplasm, allowing MPM to image the cellular structures in the corneal epithelium and endothelium. SHG signals are observed from collagen, an abundant connective tissue found in the stroma. Optical coherence tomography (OCT) produces cross-sectional, structural images based on the interference fringes created by the reflected light from the sample and reference arms. Our system uses a single sub-10 fs Ti: sapphire laser source which is good for both MPM excitation and OCT resolution. The MPM and OCT images are coregistered when they are taken successively because their axial resolutions are similar and the system shares the laser source and the scanning unit. We can calculate the RI by measuring the optical thickness and the optical path length of the cornea from the MPM and OCT images respectively. We have imaged and calculated the RI of murine and piscine corneas. We were able to see the epithelial, stromal, and endothelial layers and compare their relative thicknesses and the organization of the stromal collagen lamellae. Our results showed that our system can provide both functional and structural information about the cornea and measure the RI of multi-layered tissues.

  11. Effect of laser spectral bandwidth on coherent control of resonance-enhanced multiphoton-ionization photoelectron spectroscopy

    SciTech Connect

    Xu, Shuwu; School of Science, Nantong University, Nantong 226007 ; Ding, Jingxin Lu, Chenhui; Jia, Tianqing; Zhang, Shian Sun, Zhenrong

    2014-02-28

    The high-resolution (2 + 1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy (REMPI-PS) can be obtained by measuring the photoelectron intensity at a given kinetic energy and scanning the single ? phase step position. In this paper, we further demonstrate that the high-resolution (2 + 1) REMPI-PS cannot be achieved at any measured position of the kinetic energy by this measurement method, which is affected by the laser spectral bandwidth. We propose a double ? phase step modulation to eliminate the effect of the laser spectral bandwidth, and show the advantage of the double ? phase step modulation on achieving the high-resolution (2 + 1) REMPI-PS by considering the contributions involving on- and near-resonant three-photon excitation pathways.

  12. Label-free imaging and quantitative chemical analysis of Alzheimer's disease brain samples with multimodal multiphoton nonlinear optical microspectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jang Hyuk; Kim, Dae Hwan; Song, Woo Keun; Oh, Myoung-Kyu; Ko, Do-Kyeong

    2015-05-01

    We developed multimodal multiphoton microspectroscopy using a small-diameter probe with gradient-index lenses and applied it to unstained Alzheimer's disease (AD) brain samples. Our system maintained the image quality and spatial resolution of images obtained using an objective lens of similar numerical aperture. Multicolor images of AD brain samples were obtained simultaneously by integrating two-photon excited fluorescence and second-harmonic generation on a coherent anti-Stokes Raman scattering (CARS) microendoscope platform. Measurements of two hippocampal regions, the cornus ammonis-1 and dentate gyrus, revealed more lipids, amyloid fibers, and collagen in the AD samples than in the normal samples. Normal and AD brains were clearly distinguished by a large spectral difference and quantitative analysis of the CH mode using CARS microendoscope spectroscopy. We expect this system to be an important diagnosis tool in AD research.

  13. Multiphoton microscopic imaging of histological sections without hematoxylin and eosin staining differentiates carcinoma in situ lesion from normal oesophagus

    NASA Astrophysics Data System (ADS)

    Chen, Jianxin; Xu, Jian; Kang, Deyong; Xu, Meifang; Zhuo, Shuangmu; Zhu, Xiaoqin; Jiang, Xingshan

    2013-10-01

    Multiphoton microscopy (MPM) has become a powerful, important tool for tissues imaging at the molecular level. In this paper, this technique was extended to histological investigations, differentiating carcinoma in situ (CIS) lesion from normal oesophagus by imaging histological sections without hematoxylin and eosin (H&E) staining. The results show that the histology procedures of dehydration, paraffin embedding, and de-paraffinizing highlighted two photon excited fluorescence of cytoplasm and nucleolus of epithelial cell and collagen in stroma. MPM has the ability to identify the characteristics of CIS lesion including changes of squamous cells and full epithelium, identification of basement membrane, especially prominent nucleolus. The studies described here show that MPM has the potential for future retrospective studies of tumor staging by employing on histological section specimens without H&E staining.

  14. Signal enhancement in multiphoton imaging by the use of coated glass substrates.

    PubMed

    Lee, Sheng-Lin; Guo, Han-Wen; Chen, Yang-Fan; Dong, Chen-Yuan

    2015-09-01

    In nonlinear optical imaging of biological specimens, more than half of the generated luminescence signal is lost, when signal collection is performed in the epi-illuminated geometry. In this study, we enhanced the collected luminescence signal by the use of alternating multiply-coated layers of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) on standard microscope cover glasses that has high transmission in the near-infrared wavelength region and high reflection of the visible, luminescence signal. Our coating is biocompatible, allows visual examination of the specimens and optimize collection of the luminescence signal. We demonstrated this approach on a number of specimens including sulforhodamine solution, fluorescence microspheres, and labeled 3T3 cells. In all cases, the use of coated cover glass enhanced signal, optimally by a factor of about 2. Image analysis of labeled 3T3 cells also shows signal enhancement did not contribute to additional photobleaching. Our results show that properly designed coated cover glass can enhance detected signal in multiphoton microscopy and result in improved image quality. PMID:26417521

  15. Signal enhancement in multiphoton imaging by the use of coated glass substrates

    PubMed Central

    Lee, Sheng-Lin; Guo, Han-Wen; Chen, Yang-Fan; Dong, Chen-Yuan

    2015-01-01

    In nonlinear optical imaging of biological specimens, more than half of the generated luminescence signal is lost, when signal collection is performed in the epi-illuminated geometry. In this study, we enhanced the collected luminescence signal by the use of alternating multiply-coated layers of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) on standard microscope cover glasses that has high transmission in the near-infrared wavelength region and high reflection of the visible, luminescence signal. Our coating is biocompatible, allows visual examination of the specimens and optimize collection of the luminescence signal. We demonstrated this approach on a number of specimens including sulforhodamine solution, fluorescence microspheres, and labeled 3T3 cells. In all cases, the use of coated cover glass enhanced signal, optimally by a factor of about 2. Image analysis of labeled 3T3 cells also shows signal enhancement did not contribute to additional photobleaching. Our results show that properly designed coated cover glass can enhance detected signal in multiphoton microscopy and result in improved image quality. PMID:26417521

  16. Identification of non-neoplastic and neoplastic gastric polyps using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Shanghai; Kang, Deyong; Xu, Meifang; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

    2012-12-01

    Gastric polyps can be broadly defined as luminal lesions projecting above the plane of the mucosal surface. They are generally divided into non-neoplastic and neoplastic polyps. Accurate diagnosis of neoplastic polyps is important because of their well-known relationship with gastric cancer. Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) is one of the most important recent inventions in biological imaging. In this study, we used MPM to image the microstructure of gastric polyps, including fundic gland polyps, hyperplastic polyps, inflammatory fibroid polyps and adenomas, then compared with gold-standard hematoxylin- eosin(H-E)-stained histopathology. MPM images showed that different gastric polyps have different gland architecture and cell morphology. Dilated, elongated or branch-like hyperplastic polyps are arranged by columnar epithelial cells. Inflammatory fibroid polyps are composed of small, thin-walled blood vessels surrounded by short spindle cells. Fundic glands polyps are lined by parietal cells and chief cells, admixed with normal glands. Gastric adenomas are generally composed of tubules or villi of dysplastic epithelium, which usually show some degree of intestinal-type differentiation toward absorptive cells, goblet cells, endocrine cells. Our results demonstrated that MPM can be used to identify non- neoplastic and neoplastic gastric polyps without the need of any staining procedure.

  17. Clinical studies of pigmented lesions in human skin by using a multiphoton tomograph

    NASA Astrophysics Data System (ADS)

    Balu, Mihaela; Kelly, Kristen M.; Zachary, Christopher B.; Harris, Ronald M.; Krasieva, Tatiana B.; König, Karsten; Tromberg, Bruce J.

    2013-02-01

    In vivo imaging of pigmented lesions in human skin was performed with a clinical multiphoton microscopy (MPM)-based tomograph (MPTflex, JenLab, Germany). Two-photon excited fluorescence was used for visualizing endogenous fluorophores such as NADH/FAD, keratin, melanin in the epidermal cells and elastin fibers in the dermis. Collagen fibers were imaged by second harmonic generation. Our study involved in vivo imaging of benign melanocytic nevi, atypical nevi and melanoma. The goal of this preliminary study was to identify in vivo the characteristic features and their frequency in pigmented lesions at different stages (benign, atypical and malignant) and to evaluate the ability of in vivo MPM to distinguish atypical nevi from melanoma. Comparison with histopathology was performed for the biopsied lesions. Benign melanocytic nevi were characterized by the presence of nevus cell nests at the epidermal-dermal junction. In atypical nevi, features such as lentiginous hyperplasia, acanthosis and architectural disorder were imaged. Cytological atypia was present in all the melanoma lesions imaged, showing the strongest correlation with malignancy. The MPM images demonstrated very good correlation with corresponding histological images, suggesting that MPM could be a promising tool for in vivo non-invasive pigmented lesion diagnosis, particularly distinguishing atypical nevi from melanoma.

  18. Atomic force microscopy based, multiphoton, photoelectron emission imaging

    SciTech Connect

    Spanakis, E.; Chimmalgi, A.; Stratakis, E.; Grigoropoulos, C. P.; Fotakis, C.; Tzanetakis, P.

    2006-07-03

    Images of photoelectron emission from metallic surfaces were obtained with a modified atomic force microscope operating in air. Illumination of the samples was achieved in the near field of a metal-coated microcantilever tip, placed in the beam of a femtosecond pulsed laser that is incident at a grazing angle with respect to the sample surface. Photoelectron currents were measured through the tip with a prototype amplifier. The power law dependence of average photocurrent on light intensity is compatible with multiphoton photoelectric effect and the work function of the metal covering a particular area on the two-metal patterned samples used.

  19. Dynamic Multiphoton Microscopy: Focusing Light on Acute Kidney Injury

    PubMed Central

    Molitoris, Bruce A.

    2014-01-01

    Acute kidney injury (AKI) is a major global health problem; much research has been conducted on AKI, and numerous agents have shown benefit in animal studies, but none have translated into treatments. There is, therefore, a pressing unmet need to increase knowledge of the pathophysiology of AKI. Multiphoton microscopy (MPM) provides a tool to non-invasively visualize dynamic events in real time and at high resolution in rodent kidneys, and in this article we review its application to study novel mechanisms and treatments in different forms of AKI. PMID:25180263

  20. High-Visibility Multi-Photon Interference of Classical Light

    E-print Network

    I. N. Agafonov; M. V. Chekhova; T. Sh. Iskhakov; A. N. Penin

    2007-05-07

    It is shown that the visibility of multi-photon interference for classical sources grows rapidly with the order of interference. For three-photon and four-photon interference of two coherent sources, the visibility can be as high as 81.9% and 94.4%, respectively, - much higher than the 'classical limit' of two-photon interference (50%). High-visibility three-photon and four-photon interference has been observed in experiment, for both coherent and pseudo-thermal light.

  1. Multifocal multiphoton microscopy based on a spatial light modulator

    PubMed Central

    Shao, Y.; Qin, W.; Liu, H.; Peng, X.; Niu, H.

    2013-01-01

    We present a new multifocal multiphoton microscope that employs a programmable spatial light modulator to generate dynamic multifocus arrays which can be rapidly scanned by changing the incident angle of the laser beam using a pair of galvo scanners. Using this microscope, we can rapidly select the number and the spatial density of focal points in a multifocus array, as well as the locations and shapes of arrays according to the features of the areas of interest in the field of view without any change to the hardware. PMID:23894222

  2. Microstructure imaging of human rectal mucosa using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liu, N. R.; Chen, G.; Chen, J. X.; Yan, J.; Zhuo, S. M.; Zheng, L. Q.; Jiang, X. S.

    2011-01-01

    Multiphoton microscopy (MPM) has high resolution and sensitivity. In this study, MPM was used to image microstructure of human rectal mucosa. The morphology and distribution of the main components in mucosa layer, absorptive cells and goblet cells in the epithelium, abundant intestinal glands in the lamina propria and smooth muscle fibers in the muscularis mucosa were clearly monitored. The variations of these components were tightly relevant to the pathology in gastrointestine system, especially early rectal cancer. The obtained images will be helpful for the diagnosis of early colorectal cancer.

  3. Vacuum ultraviolet and near-infrared excited luminescence properties of Ca{sub 3}(PO{sub 4}){sub 2}:RE{sup 3+}, Na{sup +} (RE=Tb, Yb, Er, Tm, and Ho)

    SciTech Connect

    Zhang Jia; Wang Yuhua; Guo Linna; Zhang Feng; Wen Yan; Liu Bitao; Huang Yan

    2011-08-15

    Tb{sup 3+}, Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2} were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb{sup 3+}-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb{sup 3+} content is comparable with that of the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb{sup 3+}-Ho{sup 3+}, Yb{sup 3+}-Er{sup 3+}, and Yb{sup 3+}-Tm{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, in which the cross-relaxation process between Er{sup 3+} and Tm{sup 3+}, producing the {sup 1}D{sub 2}-{sup 3}F{sub 4} transition of Tm{sup 3+}, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams. - Graphical abstract: The CPO:0.25Tb{sup 3+}, 0.25Na{sup +} exhibits a comparable brightness to the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} upon 147 nm excitation. Good white light color is achieved in CPO:Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} under 980 nm excitation. Highlights: > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+},Na{sup +} exhibits a comparable brightness with commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+}. > Red, green and blue colors are achieved in Yb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2}. > Good white emission is obtained in Yb{sup 3+}-Ho{sup 3+}-Er{sup 3+}-Tm{sup 3+} quadri-doped Ca{sub 3}(PO{sub 4}){sub 2}. > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+}, Yb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+} could be potential phosphors.

  4. Modulation of the pupil function of microscope objective lens for multifocal multi-photon microscopy using a spatial light modulator

    NASA Astrophysics Data System (ADS)

    Matsumoto, Naoya; Okazaki, Shigetoshi; Takamoto, Hisayoshi; Inoue, Takashi; Terakawa, Susumu

    2014-02-01

    We propose a method for high precision modulation of the pupil function of a microscope objective lens to improve the performance of multifocal multi-photon microscopy (MMM). To modulate the pupil function, we adopt a spatial light modulator (SLM) and place it at the conjugate position of the objective lens. The SLM can generate an arbitrary number of spots to excite the multiple fluorescence spots (MFS) at the desired positions and intensities by applying an appropriate computer-generated hologram (CGH). This flexibility allows us to control the MFS according to the photobleaching level of a fluorescent protein and phototoxicity of a specimen. However, when a large number of excitation spots are generated, the intensity distribution of the MFS is significantly different from the one originally designed due to misalignment of the optical setup and characteristics of the SLM. As a result, the image of a specimen obtained using laser scanning for the MFS has block noise segments because the SLM could not generate a uniform MFS. To improve the intensity distribution of the MFS, we adaptively redesigned the CGH based on the observed MFS. We experimentally demonstrate an improvement in the uniformity of a 10 × 10 MFS grid using a dye solution. The simplicity of the proposed method will allow it to be applied for calibration of MMM before observing living tissue. After the MMM calibration, we performed laser scanning with two-photon excitation to observe a real specimen without detecting block noise segments.

  5. Efficient three-photon excited deep blue photoluminescence and lasing of diphenylamino and 1,2,4-triazole endcapped oligofluorenes.

    PubMed

    Wu, Po Lam; Feng, Xin Jiang; Tam, Hoi Lam; Wong, Man Shing; Cheah, Kok Wai

    2009-01-28

    A novel homologues series of diphenylamino and 1,2,4-triazole endcapped pi-conjugated oligofluorenes has been synthesized using palladium-catalyzed Suzuki cross-coupling of 9,9-dibutyl-7-(diphenylamino)-2-fluorenylboronic acid, and 1,2,4,-triazole-substituted oligofluorenyl halide was used as a key step. Efficient two- and three-photon excited photoluminescence and lasing were obtained by pumping with near-infrared femto-second lasers. The three-photon absorption cross-section enhances significantly up to 2.48 x 10(-78) cm(6) s(2) in the femtosecond regime with the length of the conjugation system. The emission is in the deep blue region and the best full width half-maximum (fwhm) of the three-photon lasing is narrower than 6 nm which is the narrowest ever reported. It was also shown that the nonlinear optics (NLO) effect increased parabolically with the conjugation length but without changing the emission wavelength. This demonstrates that varying the conjugation length is a very effective way to tailor an OF-based NLO device for deep blue application. Our findings open a new avenue to design highly efficient multiphoton absorption molecules for photoluminescence and lasing as well as provide a novel series of organic molecules that can be used in NLO applications and fundamental study. PMID:19154170

  6. Using adaptive optics for deep in-vivo multiphoton FLIM

    NASA Astrophysics Data System (ADS)

    Poland, Simon; Fruhwirth, Gilbert; Ng, Tony; Ameer-beg, Simon

    2011-03-01

    Multiphoton microscopy (MPM) is a high resolution (sub-?m) 3D optical imaging technique that has seen widespread use for microscopy at moderate depth within biological tissue (~1 mm). MPM combined with Fluorescence lifetime imaging (FLIM) and Fluorescent resonant energy transfer (FRET) provides the ability to image protein-protein interactions. When applied in-vivo at depth, it will be a key component to identifying and evaluating drug interaction in tumours. Unfortunately as one images more deeply into biological tissue, depth is restricted due to the specimen induced aberrations, which result in deterioration in both the image quality and resolution. Adaptive optics (AO), a technique first developed for astronomy, has been shown to be successful in overcoming problems associated with imaging in depth in confocal, multiphoton, CARS and SHG microscopy. The principle relies on shaping the wavefront with a wavefront modulator to compensate for the distortions introduced by the biological tissue sample. The success of such a technique relies on being able to correctly determine the mirror shape required In this paper we will discuss the development a dedicated MPM FLIM-FRET microscope incorporating an AO for use in-vivo applications. Using a deformable membrane mirror as a wavefront modulator, a strategy for implementation will be discussed.

  7. The effect of radial polarization in multiphoton lithography

    NASA Astrophysics Data System (ADS)

    Lin, Le; Zheng, Mei-Ling; Dong, Xian-Zi; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2015-10-01

    Considering the axially symmetric polarization and intensity distribution, radially polarized (RP) laser beam has comparatively higher axial component of electric field and smaller size of focal spot compared to linearly polarized (LP) laser. In this study, the effect of radial polarization on multiphoton fabrication has been studied, and polymer spots and lines are chosen as the study objects of 2D micro/nano structures of multiphoton lithography. These structures were fabricated with IP-L, a commercial negative photoresist, by RP fs-pulse laser beam which was tightly focused by an objective lens with high numerical aperture. Multiple experimental conditions, such as fabrication power, exposure time and scanning velocity, were verified in order to observe the structural variation of these polymer structures. On the basis of measurement from images of the scanning electron microscope, the transverse and longitudinal sizes of polymer spots and lines could be analyzed, and the relationship between the aspect ratio (AR) and the above experimental conditions could be acquired. The statistical results agree with our predictions that the RP laser beam can significantly reduce the AR, and the AR in RP laser fabrication has little correlation with conditions besides fabrication power, such as exposure time and scanning velocity.

  8. Rigid and high NA multiphoton fluorescence GRIN-endoscopes

    NASA Astrophysics Data System (ADS)

    Schenkl, Selma; Ehlers, Alexander; Le Harzic, Ronan; Stark, Martin; Riemann, Iris; Messerschmidt, Bernhard; Kaatz, Martin; König, Karsten

    2007-07-01

    Multiphoton autofluorescence imaging offers minimal-invasive examination of cells without the need of staining and complicated confocal detection systems. Therefore, it is especially interesting for non-invasive clinical diagnostics. To extend this sophisticated technique from superficial regions to deep lying cell layers, internal body parts and specimens difficult of access, the bulky optics need to be reduced in diameter. This is done by tiny GRIN-optics, based on a radial gradient in the reflective index. Of especial interest for multi-photon applications is the newly developed GRIN-lens assembly with increased numerical aperture. High resolution images of plant tissue, hair and cells show the improved image quality,compared to classical GRIN-lenses. The rigid GRIN-endoscopes are already applied in wound healing studies. Here, the GRIN-lenses with diameters smaller than 3 mm enter small skin depressions. They reproduce the focus of a conventional laser scanning tomograph tens of mm apart in the specimen under study. We present first clinical measurements of elastin and SHG of collagen of in-vivo human skin of venous ulcers (ulcer curis).

  9. Simultaneous multiple-excitation multiphoton microscopy yields increased imaging sensitivity and specificity

    E-print Network

    Butko, Margaret T; Drobizhev, Mikhail; Makarov, Nikolay S; Rebane, Aleksander; Brinkman, Brendan C; Gleeson, Joseph G

    2011-01-01

    Note that cell movement was robust for green and red neuronsNote that cell movement was robust for green and red neuronsgreen- and red-fluorescing cells in the imaging plane were traced over a 12-hour imaging window (white and grey arrows, respectively), and movement

  10. Fringe-free, Background-free, Collinear Third Harmonic Generation FROG Measurements for Multiphoton Microscopy

    SciTech Connect

    Chadwick, R; Spahr, E; Squier, J A; Durfee, C G; Walker, B C; Fittinghoff, D N

    2006-07-21

    Collinear pulse measurement tools useful at the full numerical aperture (NA) of multiphoton microscope objectives are a necessity for a quantitative characterization of the femtosecond pulses focused by these systems. In this letter, we demonstrate a simple new technique, for characterizing the pulse at the focus in a multiphoton microscope. This technique, a background-free, fringe-free, form of frequency-resolved optical gating, uses the third harmonic signal generated from a glass coverslip. Here it is used to characterize 100 fs pulses (typical values for a multiphoton microscope) at the focus of a 0.65 NA objective.

  11. Ultratrace detection of chemical warfare agent simulants using supersonic-molecular-beam, resonance-enhanced multiphoton-ionization, time-of-flight mass spectroscopy. Final report

    SciTech Connect

    Syage, J.A.; Pollard, J.E.; Cohen, R.B.

    1988-02-15

    An ultratrace detection method that offers exceptional selectivity has been developed based on the technique of supersonic molecular beam, resonance enhanced multiphoton ionization, time-of-flight mass spectroscopy (MB/REMPI/TOFMS). Single ion detection capability has given detection limits as low as 300 ppt (dimethyl sulfide). Single vibronic level REMPI of the supercooled molecules in conjunction with TOFMS provides selectivity of 10,000 against chemically similar compounds. Studies were carried out using moist air expansions for a variety of organophosphonate and sulfide chemical warfare agent (CWA) simulant molecules. The preparation of molecules in single vibronic levels by laser excitation in supersonic molecular beams has enabled us to record high resolution spectra of higher excited electronic states showing fully resolved vibrational structure for diisopropyl methylphosphonate (DIMP) and dimethyl sulfide (DMS). VUV absorption spectra have also been recorded for several CWA molecules at ambient temperature, revealing several new electronic states extending up to the ionization threshold.

  12. Simultaneous imaging of GFP, CFP and collagen in tumors in vivousing multiphoton microscopy

    E-print Network

    Sahai, Erik

    Background: The development of multiphoton laser scanning microscopy has greatly facilitated the imaging of living tissues. However, the use of genetically encoded fluorescent proteins to distinguish different cell types ...

  13. Single-wavelength reflected confocal and multiphoton microscopy for tissue imaging

    E-print Network

    So, Peter T. C.

    Both reflected confocal and multiphoton microscopy can have clinical diagnostic applications. The successful combination of both modalities in tissue imaging enables unique image contrast to be achieved, especially if a ...

  14. New Development of Theoretical and Computational Methods for Probing Strong-Field Multiphoton Processes

    E-print Network

    Son, Sang-Kil

    2009-12-02

    The study of the strong-field multiphoton processes is a subject of much current significance in physics and chemistry. Recent progress of laser technology has triggered a burst of attosecond science where the electron dynamics plays a vital role...

  15. Application of state-multipole Heisenberg equations to Raman excitation dynamics

    SciTech Connect

    Shore, B.W.; Sacks, R.; Dixit, S.N.

    1987-09-10

    Description of detailed temporal excitation dyanmics for coherent excitation, such as is produced by idealized laser radiation, contrasts with evaluation of rate coefficients by means of generalized Golden Rule procedures; it requires an appropriate time-dependent Schroedinger equation. When the atom undergoing excitation is also affected by incoherent processes, such as collisions, this equation no longer suffices. The Heisenberg equations, or equivalent density-matrix equations, permit treatment in which coherence and incoherence play comparable roles in the excitation dynamics. Unlike rate equations, such equations must incorporate complexities that originate in the orientation degeneracy expressed by magnetic quantum numbers. In simple cases of coherent excitation, both for single-photon and multiphoton excitation, the sublevels merely require an average of 2J+1 independent Schroedinger equations. Relaxation couples the independent equations. It has been known for some time that appropriate state-multipole operators can simplify the description of many phenomena connected with optical pumping. This memo discusses application of these multipole operators to the description of Raman (or more general multiphoton) coherent excitation. In some simple limiting cases the equations simplify, but in general one has a hierarchy of coupled multipole polarizations and coherences in place of the populations and coherences that occur as variables in nondegenerate systems. 28 refs., 4 figs.

  16. Infrared Investigations.

    ERIC Educational Resources Information Center

    Lascours, Jean; Albe, Virginie

    2001-01-01

    Describes a series of simple and nontraditional experiments that enable students to discover the properties of infrared radiation by studying the propagation, reflection, diffusion, and refraction of infrared. The experiments rely on two modules, an infrared transmitter and an infrared receiver. (SAH)

  17. Multi-photon absorption limits to heralded single photon sources

    PubMed Central

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

    2013-01-01

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

  18. Molecule-specific darkfield and multiphoton imaging using gold nanocages

    NASA Astrophysics Data System (ADS)

    Powless, Amy J.; Jenkins, Samir V.; McKay, Mary Lee; Chen, Jingyi; Muldoon, Timothy J.

    2015-03-01

    Due to their robust optical properties, biological inertness, and readily adjustable surface chemistry, gold nanostructures have been demonstrated as contrast agents in a variety of biomedical imaging applications. One application is dynamic imaging of live cells using bioconjugated gold nanoparticles to monitor molecule trafficking mechanisms within cells; for instance, the regulatory pathway of epidermal growth factor receptor (EGFR) undergoing endocytosis. In this paper, we have demonstrated a method to track endocytosis of EGFR in MDA-MB-468 breast adenocarcinoma cells using bioconjugated gold nanocages (AuNCs) and multiphoton microscopy. Dynamic imaging was performed using a time series capture of 4 images every minute for one hour. Specific binding and internalization of the bioconjugated AuNCs was observed while the two control groups showed non-specific binding at fewer surface sites, leading to fewer bound AuNCs and no internalization.

  19. Multiphoton intravital microscopy setup to visualize the mouse mammary gland

    NASA Astrophysics Data System (ADS)

    Adur, Javier; Herrera Torres, Ana M.; Masedunskas, Andrius; Baratti, Mariana O.; de Thomaz, Andre A.; Pelegati, Vitor B.; Carvalho, Hernandes F.; Cesar, Carlos L.

    2013-06-01

    Recently, light microscopy-based techniques have been extended to live mammalian models leading to the development of a new imaging approach called intravital microscopy (IVM). Although IVM has been introduced at the beginning of the last century, its major advancements have occurred in the last twenty years with the development of non-linear microscopy that has enabled performing deep tissue imaging. IVM has been utilized to address many biological questions in basic research and is now a fundamental tool that provide information on tissues such as morphology, cellular architecture, and metabolic status. IVM has become an indispensable tool in numerous areas. This study presents and describes the practical aspects of IVM necessary to visualize epithelial cells of live mouse mammary gland with multiphoton techniques.

  20. Multiphoton Microscopy and Interaction of Intense Light Pulses with Polymers

    NASA Astrophysics Data System (ADS)

    Guay, Jean-Michel

    2011-07-01

    The nanoscale manipulation of soft-matter, such as biological tissues, in its native environment has promising applications in medicine to correct for defects (eg. eye cataracts) or to destroy malignant regions (eg. cancerous tumours). To achieve this we need the ability to first image and then do precise ablation with sub-micron resolution with the same setup. For this purpose, we designed and built a multiphoton microscope and tested it on goldfish gills and bovine cells. We then studied light-matter interaction on a hard polymer (PMMA) because the nature of ablation of soft-matter in its native environment is complex and not well understood. Ablation and modification thresholds for successive laser shots were obtained. The ablation craters revealed 3D nanostructures and polarization dependent orientation. The interaction also induced localized porosity in PMMA that can be controlled.

  1. Monitoring wound healing by multiphoton tomography/endoscopy

    NASA Astrophysics Data System (ADS)

    König, Karsten; Weinigel, Martin; Bückle, Rainer; Kaatz, Martin; Hipler, Christina; Zens, Katharina; Schneider, Stefan W.; Huck, Volker

    2015-02-01

    Certified clinical multiphoton tomographs are employed to perform rapid label-free high-resolution in vivo histology. Novel tomographs include a flexible 360° scan head attached to a mechano-optical arm for autofluorescence and SHG imaging as well as rigid two-photon GRIN microendoscope. Mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged with submicron resolution in human skin. The system was employed to study the healing of chronic wounds (venous leg ulcer) and acute wounds (curettage of actinic or seborrheic keratosis) on a subcellular level. Furthermore, a flexible sterile foil as interface between wound and focusing optic was tested.

  2. In vivo multiphoton tomography in skin aging studies

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    High-resolution clinical multiphoton tomography based on the femtosecond laser system DermaInspect has been performed on hundreds of patients and volunteers in Australia, Asia, and Europe. The system enables the in vivo detection of the elastin and the collagen network as well as the imaging of melanin clusters in aging spots. The epidermis-dermis junction can be detected with submicron resolution. One major applications of this novel HighTech imaging tool is the determination of the skin aging index SAAID as well as the study of the effects of anti-aging products. In particular, the stimulated biosynthesis of collagen can be investigated over long periods of time. The system with its sub-500 nm lateral resolution is able to image age-related modifications of the extracellular matrix on the level of a single elastin fiber.

  3. Multiphoton Quantum Rabi Oscillations in Ultrastrong Cavity QED

    E-print Network

    Luigi Garziano; Roberto Stassi; Vincenzo Macrì; Anton Frisk Kockum; Salvatore Savasta; Franco Nori

    2015-09-21

    When an atom is strongly coupled to a cavity, the two systems can exchange a single photon through a coherent Rabi oscillation. This process enables precise quantum-state engineering and manipulation of atoms and photons in a cavity, which play a central role in quantum information and measurement. Recently, a new regime of cavity QED has been reached experimentally where the strength of the interaction between light and artificial atoms (qubits) becomes comparable to the atomic transition frequency or the resonance frequency of the cavity mode. Here we show that this regime can strongly modify the concept of vacuum Rabi oscillations, enabling multiphoton exchanges between the qubit and the resonator. We find that experimental state-of-the-art circuit- QED systems can undergo two- and three-photon vacuum Rabi oscillations. These anomalous Rabi oscillations can be exploited for the realization of efficient Fock-state sources of light and complex entangled states of qubits.

  4. Clinical multiphoton tomography and clinical two-photon microendoscopy

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  5. Imaging-guided two-photon excitation-emission-matrix measurements of human skin tissues

    NASA Astrophysics Data System (ADS)

    Yu, Yingqiu; Lee, Anthony M. D.; Wang, Hequn; Tang, Shuo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

    2012-07-01

    There are increased interests on using multiphoton imaging and spectroscopy for skin tissue characterization and diagnosis. However, most studies have been done with just a few excitation wavelengths. Our objective is to perform a systematic study of the two-photon fluorescence (TPF) properties of skin fluorophores, normal skin, and diseased skin tissues. A nonlinear excitation-emission-matrix (EEM) spectroscopy system with multiphoton imaging guidance was constructed. A tunable femtosecond laser was used to vary excitation wavelengths from 730 to 920 nm for EEM data acquisition. EEM measurements were performed on excised fresh normal skin tissues, seborrheic keratosis tissue samples, and skin fluorophores including: NADH, FAD, keratin, melanin, collagen, and elastin. We found that in the stratum corneum and upper epidermis of normal skin, the cells have large sizes and the TPF originates from keratin. In the lower epidermis, cells are smaller and TPF is dominated by NADH contributions. In the dermis, TPF is dominated by elastin components. The depth resolved EEM measurements also demonstrated that keratin structure has intruded into the middle sublayers of the epidermal part of the seborrheic keratosis lesion. These results suggest that the imaging guided TPF EEM spectroscopy provides useful information for the development of multiphoton clinical devices for skin disease diagnosis.

  6. Evaluating thermal damage induced by pulsed light with multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Gong, Wei; Xie, Shusen; Huang, Yimei

    2009-02-01

    Nonablative skin remodeling is a new light treatment approach for photodamaged skin. Compared to ablative CO2 or Er:YAG laser resurfacing, dermabrasion, and chemical peels, the clinical objective of nonablative skin remodeling is to maximize thermal damage to upper dermis while minimizing injury to the epidermis and surrounding tissue, consequently decreasing potential complications and shortening long recuperation periods. Histological analysis of preoperative and postoperative biopsies using H&E or special stains has indicated the dermal thermal injury, which resulting in collagen denaturation, is the most important mechanism of nonablative skin remodeling for improving skin situation. And the extent of improvement of skin situation corresponded to the formation of a new band of dense, compact collagen bundles in the papillary dermis. The diversity of individual skin condition influences the choice of pulsed light treatment parameters, and further influences the degree of dermal thermal damage, thus the efficacy of nonablative skin remodeling remains unstable. Recently, multiphoton microscopy has show a promising application for monitoring skin thermal damage, because collagen could produce strong second harmonic generation (SHG). And SHG intensity is presumably proportional to the percentage of collagen in dermis. In this paper, the auto-fluorescence (AF) intensity and SHG intensity of mice skin irradiated by pulsed Nd:YAG laser were measured and imaged with multiphoton microscope, and the results show the ratio of SHG to AF decreases with the increase of irradiation exposure dose, and could be a quantitative technique to assess dermal thermal damage, and could further benefit the choice of light treatment parameters.

  7. Recoil effects in multiphoton electron-positron pair creation

    SciTech Connect

    Krajewska, K.; Kaminski, J. Z.

    2010-07-15

    Triply differential probability rates for electron-positron pair creation in laser-nucleus collisions, calculated within the S-matrix approach, are investigated as functions of the nuclear recoil. Pronounced enhancements of differential probability rates of multiphoton pair production are found for a nonzero momentum transfer from the colliding nucleus. The corresponding rates show a very dramatic dependence on the polarization of the laser field impinging on the nucleus; only for a linearly polarized light are the multiphoton rates for electron-positron pair production considerably large. We focus therefore on this case. Our numerical results for different geometries of the reaction particles demonstrate that, for the linearly polarized laser field of an infinite extent (which is a good approximation for femtosecond laser pulses), the pair creation is far more efficient if the nucleus is detected in the direction of the laser-field propagation. The corresponding angular distributions of the created particles show that the high-energy pairs are predominantly produced in the plane spanned by the polarization vector and the laser-field propagation direction, while the low-energy pairs are rather spread around the latter of the two directions. The enhancement of differential probability rates at each energy sector, defined by the four-momentum conservation relation, is observed with varying the energy of the produced particles. The total probability rates of pair production are also evaluated and compared with the corresponding results for the case when one disregards the recoil effect. A tremendous enhancement of the total probability rates of the electron-positron pair creation is observed if one takes into account the nuclear recoil.

  8. Multiphoton gradient index endoscopy for evaluation of diseased human prostatic tissue ex vivo

    PubMed Central

    Huland, David M.; Jain, Manu; Ouzounov, Dimitre G.; Robinson, Brian D.; Harya, Diana S.; Shevchuk, Maria M.; Singhal, Paras; Xu, Chris; Tewari, Ashutosh K.

    2014-01-01

    Abstract. Multiphoton microscopy can instantly visualize cellular details in unstained tissues. Multiphoton probes with clinical potential have been developed. This study evaluates the suitability of multiphoton gradient index (GRIN) endoscopy as a diagnostic tool for prostatic tissue. A portable and compact multiphoton endoscope based on a 1-mm diameter, 8-cm length GRIN lens system probe was used. Fresh ex vivo samples were obtained from 14 radical prostatectomy patients and benign and malignant areas were imaged and correlated with subsequent H&E sections. Multiphoton GRIN endoscopy images of unfixed and unprocessed prostate tissue at a subcellular resolution are presented. We note several differences and identifying features of benign versus low-grade versus high-grade tumors and are able to identify periprostatic tissues such as adipocytes, periprostatic nerves, and blood vessels. Multiphoton GRIN endoscopy can be used to identify both benign and malignant lesions in ex vivo human prostate tissue and may be a valuable diagnostic tool for real-time visualization of suspicious areas of the prostate. PMID:25415446

  9. Infrared planar laser-induced fluorescence imaging and applications to imaging of carbon monoxide and carbon dioxide

    NASA Astrophysics Data System (ADS)

    Kirby, Brian James

    This dissertation introduces infrared planar laser- induced fluorescence (IR PLIF) techniques for visualization of species that lack convenient electronic transitions and are therefore unsuitable for more traditional electronic PLIF measurements. IR PLIF measurements can generate high signal levels that scale linearly with both laser energy and species concentration, thereby demonstrating advantages over Raman and multiphoton PLIF techniques. IR PLIF is shown to be a straightforward and effective tool for visualization of CO and CO2 in reactive flows. The slow characteristic times of vibrational relaxation and the large mole fractions of CO and CO2 in typical flows lead to high IR PLIF signal levels, despite the low emission rates typical of vibrational transitions. Analyses of rotational energy transfer (RET) and vibrational energy transfer (VET) show that excitation schemes in either linear (weak) or saturated (strong) limits may be developed, with the fluorescence collected directly from the laser-excited species or indirectly from bath gases in vibrational resonance with the laser-excited species. Use of short (~1 ?s) exposures (for CO) or short exposures combined with long-pulse, high-pulse-energy excitation (for CO2) minimizes unwanted signal variation due to spatially-dependent VET rates. Results are presented for flows ranging from room- temperature mixing to a benchmark CH4 laminar diffusion flame. Linear excitation is appropriate for CO due to its slow vibrational relaxation. However, linear excitation is not well-suited for CO2 imaging due to fast H 2O-enhanced VET processes and the attendant difficulty in interpreting the resulting signal. Saturated excitation using a CO2 laser (or combined CO2 laser-OPO) technique is most appropriate for CO 2, as it generates high signal and minimizes spatial variations in fluorescence quantum yield. Since IR PLIF is applicable to most IR-active species, it has a high potential for expanding the diagnostic possibilities available to combustion researchers. Such diagnostics might include visualization of the fuel region of lifted flames, CO-formation regions in flames, or exhaust mixing processes in internal combustion engines as applied to residual-induced autoignition.

  10. Microvascular geometry and differential permeability in the eye during inflammation revealed with dual channel multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Bateman, Ryon M.; Hodgson, Kevin; Van Breemen, Casey; Walley, Keith R.

    2006-02-01

    Microvascular permeability is a serious complication of systemic inflammation in critically ill patients; yet, no direct techniques exist to quantify this in vivo. To overcome this limitation, we investigated the use of multiphoton microscopy to evaluate fluorescent macromolecular gradients in the eye. Following the induction of systemic inflammation in a CD1 mouse, a bolus of high (250 KD FITC-dextran) and low (70 KD rhodamine-dextran) molecular weight fluorescent macromolecules was injected via the tail vein. The anesthetized mouse was positioned in such a way that different microvessels in the eye could be imaged directly using an upright microscope. The fluorophores were simultaneously excited at 840nm and a series of images including a spectral scan (480 to 680nm), an xt line scan (96 lines) and an x,y,z image stack were collected from the iris, cornea and limbal plexus at one hour intervals for four hours. A simple fluorescent gradient across the vessel wall was used as an index of microvascular permeability. In all microvessels, the LMW dye was more permeable. We found that the fluorescent gradient increased dramatically in the limbal plexus up to three hours then declined. This may indicate that circulating fluid pooled near the limbal plexus. Consistent with the thick walls and tight junctions of the iris microvessels, no significant fluorescent gradients were detected in this area. The cornea, containing a collagen filled stroma layer, was found to have both lateral and perpendicular fluorescent gradients. This work demonstrates that inflammation causes differential microvascular permeability in the mouse eye.

  11. Tunable Fabrication of Molybdenum Disulfide Quantum Dots for Intracellular MicroRNA Detection and Multiphoton Bioimaging.

    PubMed

    Dai, Wenhao; Dong, Haifeng; Fugetsu, Bunshi; Cao, Yu; Lu, Huiting; Ma, Xinlei; Zhang, Xueji

    2015-09-01

    Molybdenum disulfide (MoS2 ) quantum dots (QDs) (size <10 nm) possess attractive new properties due to the quantum confinement and edge effects as graphene QDs. However, the synthesis and application of MoS2 QDs has not been investigated in great detail. Here, a facile and efficient approach for synthesis of controllable-size MoS2 QDs with excellent photoluminescence (PL) by using a sulfuric acid-assisted ultrasonic route is developed for this investigation. Various MoS2 structures including monolayer MoS2 flake, nanoporous MoS2 , and MoS2 QDs can be yielded by simply controlling the ultrasonic durations. Comprehensive microscopic and spectroscopic tools demonstrate that the MoS2 QDs have uniform lateral size and possess excellent excitation-independent blue PL. The as-generated MoS2 QDs show high quantum yield of 9.65%, long fluorescence lifetime of 4.66 ns, and good fluorescent stability over broad pH values from 4 to 10. Given the good intrinsic optical properties and large surface area combined with excellent physiological stability and biocompatibility, a MoS2 QDs-based intracellular microRNA imaging analysis system is successfully constructed. Importantly, the MoS2 QDs show good performance as multiphoton bioimaging labeling. The proposed synthesis strategy paves a new way for facile and efficient preparing MoS2 QDs with tunable-size for biomedical imaging and optoelectronic devices application. PMID:26033986

  12. Excited Insects

    E-print Network

    Hacker, Randi

    2011-04-06

    but not killing them doesn't actually count as true celebration. Now, China. There's a country that knows how to make a bug feel good. Bugs have their very own holiday in the Chinese calendar. It's called the Feast of the Excited Insects and it falls on March 5th...

  13. Mid-infrared soliton and Raman frequency comb generation in silicon microrings.

    PubMed

    Hansson, Tobias; Modotto, Daniele; Wabnitz, Stefan

    2014-12-01

    We numerically study the mechanisms of frequency comb generation in the mid-infrared spectral region from cw-pumped silicon microring resonators. Coherent soliton comb generation may be obtained even for a pump with zero linear cavity detuning, through suitable control of the effective lifetime of free carriers from multiphoton absorption, which introduces a nonlinear cavity detuning via free-carrier dispersion. Conditions for optimal octave spanning Raman comb generation are also described. PMID:25490668

  14. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  15. Excited baryons

    SciTech Connect

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  16. Simultaneous two-photon excitation of photodynamic therapy agents

    SciTech Connect

    Wachter, E.A.; Fisher, W.G. |; Partridge, W.P.; Dees, H.C.; Petersen, M.G.

    1998-01-01

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

  17. Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

    NASA Astrophysics Data System (ADS)

    dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n -mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [

    F. Dell’Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)
    ], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.

  18. Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n-mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [F. Dell'Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.

  19. Particle Beam Excitation Electron Beam Excitation

    E-print Network

    Schroder, Dieter K.

    Particle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAM Backscattering Spectrometry (RBS) X-ray Excitation X-ray Fluorescence (XRF) X-ray Photoelectron Spectroscopy (XPS

  20. Multiphoton absorption in polydiacetylenes adsorbed on metal nanostructures

    NASA Astrophysics Data System (ADS)

    Pilot, R.; Bozio, R.; Demartini, A.; Alloisio, M.; Dellepiane, G.; Giorgetti, E.

    2010-05-01

    We report on the measurement of the multi-photon absorption dispersion of polydiacetylene-decorated silver nanoparticles in water solution. They were prepared by self assembly of the monomer 10,12-pentacosadiynoic acid (PCDA) onto pre-formed chitosan-stabilized Ag nanoparticles (Chit-AgNps) followed by photopolymerization of the diacetylenic outer shell. Z-Scan technique with fs pulses in open aperture configuration was employed: the spectral range covered the region between 1150 and 1350 nm. We tentatively attribute our results to a two photon state (2Ag) which peaks at 600 nm. This result is consistent with the fluorescence spectrum that shows an emitting state lying at about 650 nm, in addition to a peak at 568 nm which is attributed to the emission of an orange form of the polymer. However we cannot rule out the possibility that we are also dealing with higher order absorption processes and further studies are needed to clarify this point and to provide a deeper insight into the origin of the emission spectrum.

  1. Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy

    NASA Astrophysics Data System (ADS)

    Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

    2013-03-01

    The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

  2. Intravital Multiphoton Imaging of the Kidney: Tubular Structure and Metabolism.

    PubMed

    Small, David M; Sanchez, Washington Y; Gobe, Glenda C

    2016-01-01

    Multiphoton microscopy (MPM) allows the visualization of dynamic pathophysiological events in real time in live animals. Intravital imaging can be applied to investigate novel mechanisms and treatments of different forms of kidney disease as well as improve our understanding of normal kidney physiology. Using rodent models, in conjunction with endogenous fluorescence and infused exogenous fluorescent dyes, measurement can be made of renal processes such as glomerular permeability, juxtaglomerular apparatus function, interactions of the tubulointerstitium, tubulovascular interactions, vascular flow rate, and the renin-angiotensin-aldosterone system. Subcellular processes including mitochondrial dynamics, reactive oxygen species production, cytosolic ion concentrations, and death processes of apoptosis and necrosis can also be seen and measured by MPM. The current methods chapter presents an overview of MPM with a focus on techniques for intravital kidney imaging and gives examples of instances where intravital MPM has been utilized to study renal pathophysiology. Suggestions are provided for MPM methods within the confines of intravital microscopy and selected kidney structure. MPM is undoubtedly a powerful new technique for application in experimental nephrology, and we believe it will continue to create new paradigms for understanding and treating kidney disease. PMID:26676133

  3. Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes

    NASA Astrophysics Data System (ADS)

    Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

    2013-03-01

    The aqueous outflow system (AOS), including the trabecular meshwork (TM), the collector channels (CC) and the Schlemm's canal (SC), regulates intraocular pressure (IOP) through the drainage of the aqueous humor (AH). Abnormal IOP elevation leads to increased pressure stress to retinal ganglion cells, resulting in cell loss that can ultimately lead to complete loss of eyesight. Therefore, development of imaging tools to detect abnormal structural and functional changes of the AOS is important in early diagnosis and prevention of glaucoma. Multiphoton microscopy (MPM), including twophoton autofluorescence (TPAF) and second harmonic generation (SHG), is a label-free microscopic technique that allows molecular specific imaging of biological tissues like the TM. Since the TM and other AOS structures are located behind the highly scattering scleral tissue, transscleral imaging of the TM does not provide enough optical resolution. In this work, a gonioscopic lens is used to allow direct optical access of the TM through the cornea for MPM imaging. Compared to transscleral imaging, the acquired MPM images show improved resolution as individual collagen fiber bundles of the TM can be observed. MPM gonioscopy may have the potential to be developed as a future clinical imaging tool for glaucoma diagnostics.

  4. Label-free and depth resolved optical sectioning of iron-complex deposits in sickle cell disease splenic tissue by multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Vigil, Genevieve D.; Adami, Alexander J.; Ahmed, Tahsin; Khan, Aamir; Chapman, Sarah; Andemariam, Biree; Thrall, Roger S.; Howard, Scott S.

    2015-06-01

    Multiphoton microscopy (MPM) imaging of intrinsic two-photon excited fluorescence (TPEF) is performed on humanized sickle cell disease (SCD) mouse model splenic tissue. Distinct morphological and spectral features associated with SCD are identified and discussed in terms of diagnostic relevance. Specifically, spectrally unique splenic iron-complex deposits are identified by MPM; this finding is supported by TPEF spectroscopy and object size to standard histopathological methods. Further, iron deposits are found at higher concentrations in diseased tissue than in healthy tissue by all imaging methods employed here including MPM, and therefore, may provide a useful biomarker related to the disease state. These newly characterized biomarkers allow for further investigations of SCD in live animals as a means to gain insight into the mechanisms impacting immune dysregulation and organ malfunction, which are currently not well understood.

  5. Tri-modal microscopy with multiphoton and optical coherence microscopy/tomography for multi-scale and multi-contrast imaging

    PubMed Central

    Chong, Shau Poh; Lai, Tom; Zhou, Yifeng; Tang, Shuo

    2013-01-01

    Multi-scale multimodal microscopy is a very useful technique by providing multiple imaging contrasts with adjustable field of views and spatial resolutions. Here, we present a tri-modal microscope combining multiphoton microscopy (MPM), optical coherence microscopy (OCM) and optical coherence tomography (OCT) for subsurface visualization of biological tissues. The advantages of the tri-modal system are demonstrated on various biological samples. It enables the visualization of multiple intrinsic contrasts including scattering, two-photon excitation fluorescence (TPEF), and second harmonic generation (SHG). It also enables a rapid scanning over a large tissue area and a high resolution zoom-in for cellular-level structures on regions of interest. The tri-modal microscope can be important for label-free imaging to obtain a sufficient set of parameters for reliable sample analysis. PMID:24049679

  6. Label-free and depth resolved optical sectioning of iron-complex deposits in sickle cell disease splenic tissue by multiphoton microscopy.

    PubMed

    Vigil, Genevieve D; Adami, Alexander J; Ahmed, Tahsin; Khan, Aamir; Chapman, Sarah; Andemariam, Biree; Thrall, Roger S; Howard, Scott S

    2015-06-01

    Multiphoton microscopy (MPM) imaging of intrinsic two-photon excited fluorescence (TPEF) is performed on humanized sickle cell disease (SCD) mouse model splenic tissue. Distinct morphological and spectral features associated with SCD are identified and discussed in terms of diagnostic relevance. Specifically, spectrally unique splenic iron-complex deposits are identified by MPM; this finding is supported by TPEF spectroscopy and object size to standard histopathological methods. Further, iron deposits are found at higher concentrations in diseased tissue than in healthy tissue by all imaging methods employed here including MPM, and therefore, may provide a useful biomarker related to the disease state. These newly characterized biomarkers allow for further investigations of SCD in live animals as a means to gain insight into the mechanisms impacting immune dysregulation and organ malfunction, which are currently not well understood. PMID:26042382

  7. Flexible digital signal processing architecture for narrowband and spread-spectrum lock-in detection in multiphoton microscopy and time-resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Wilson, Jesse W.; Park, Jong Kang; Warren, Warren S.; Fischer, Martin C.

    2015-03-01

    The lock-in amplifier is a critical component in many different types of experiments, because of its ability to reduce spurious or environmental noise components by restricting detection to a single frequency and phase. One example application is pump-probe microscopy, a multiphoton technique that leverages excited-state dynamics for imaging contrast. With this application in mind, we present here the design and implementation of a high-speed lock-in amplifier on the field-programmable gate array (FPGA) coprocessor of a data acquisition board. The most important advantage is the inherent ability to filter signals based on more complex modulation patterns. As an example, we use the flexibility of the FPGA approach to enable a novel pump-probe detection scheme based on spread-spectrum communications techniques.

  8. induced by 1,540-nm laser excitation

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Wang, X. F.; He, W. Y.; Bu, Y. Y.; Yan, X. H.

    2014-06-01

    The multi-photon ultraviolet upconversion emission properties and synergistic effect are investigated in BaSr2Y6O12:Er3+ phosphor. The deep-ultraviolet emissions centered at 274, 297 and 324-nm are observed under the 1,540-nm excitation, which results from a seven-, six- and six-photon upconversion process, respectively. A synergistic effect is found, which shows that the red emission intensity under 351- and 1,540-nm dual excitation is 4.7 % time stronger than the sum of red emission intensities under the 351 and 1,540-nm single excitation. This phenomenon is attributed to the 4I13/2 and 4I11/2 levels of Er3+ from non-radiative transition process under the 351-nm excitation are excited again to 4F9/2 level by absorbing 1,540-nm photon in the 351- and 1,540-nm dual-excitation process.

  9. Label-free multiphoton imaging and photoablation of preinvasive cancer cells

    NASA Astrophysics Data System (ADS)

    Zhuo, Shuangmu; Chen, Jianxin; Wu, Guizhu; Zhu, Xiaoqin; Jiang, Xingshan; Xie, Shusen

    2012-01-01

    Detection and treatment of early lesions in epithelial tissue offer several possibilities for curing cancer, but it is challenging. Here, we present an optical technique, the combination of multiphoton imaging and absorption, to label-freely detect and ablate preinvasive cancer cells in epithelial tissue. We find that multiphoton imaging can label-freely visualize the principal features of nuclear atypia associated with epithelial precancerous lesions, and the spatial localization of multiphoton absorption can perform targeted ablation of preinvasive cancer cells with micrometer-sized volume precision. These results indicate that this optical technique has the capability to label-freely visualize and remove preinvasive cancer cells in epithelial tissue. This study highlights the potential of this technique as a "seek-and-treat" tool for early lesions in epithelial tissue.

  10. Cellular organization and spectral diversity of GFP-like proteins in live coral cells studied by single and multiphoton imaging and microspectroscopy

    NASA Astrophysics Data System (ADS)

    Salih, Anya; Cox, Guy C.; Larkum, Anthony W.

    2003-07-01

    Tissues of many marine invertebrates of class Anthozoa contain intensely fluorescent or brightly coloured pigments. These pigments belong to a family of photoactive proteins closely related to Green Fluorescent Protein (GFP), and their emissions range from blue to red wavelengths. The great diversity of these pigments has only recently been realised. To investigate the role of these proteins in corals, we have performed an in vivo fluorescent pigment (FP) spectral and cellular distribution analyses in live coral cells using single and multi-photon laser scanning imaging and microspectroscopy. These analyses revealed that even single colour corals contain spectroscopically heterogeneous pigment mixtures, with 2-5 major colour types in the same area of tissue. They were typically arranged in step-wise light emission energy gradients (e.g. blue, green, yellow, red). The successive overlapping emission-excitation spectral profiles of differently coloured FPs suggested that they were suited for sequential energy coupling. Traces of red FPs (emission = 570-660 nm) were present, even in non-red corals. We confirmed that radiative energy transfer could occur between separate granules of blue and green FPs and that energy transfer was inversely proportional to the square of the distance between them. Multi-photon micro-spectrofluorometric analysis gave significantly improved spectral resolution by restricting FP excitation to a single point in the focal plane of the sample. Pigment heterogeneity at small scales within granules suggested that fluorescence resonance energy transfer (FRET) might be occurring, and we confirmed that this was the case. Thus, energy transfer can take place both radiatively and by FRET, probably functioning in photoprotection by dissipation of excessive solar radiation.

  11. Multiphoton microscopy for the in-situ investigation of cellular processes and integrity in cryopreservation.

    PubMed

    Doerr, Daniel; Stark, Martin; Ehrhart, Friederike; Zimmermann, Heiko; Stracke, Frank

    2009-08-01

    In this study we demonstrate a new noninvasive imaging method to monitor freezing processes in biological samples and to investigate life in the frozen state. It combines a laser scanning microscope with a computer-controlled cryostage. Nearinfrared (NIR) femtosecond laser pulses evoke the fluorescence of endogenous fluorophores and fluorescent labels due to multiphoton absorption.The inherent optical nonlinearity of multiphoton absorption allows 3D fluorescence imaging for optical tomography of frozen biological material in-situ. As an example for functional imaging we use fluorescence lifetime imaging (FLIM) to create images with chemical and physical contrast. PMID:19360710

  12. Label-free diagnosis of human hepatocellular carcinoma by multiphoton autofluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Sun, Tzu-Lin; Liu, Yuan; Sung, Ming-Chin; Chen, Hsiao-Ching; Yang, Chun-Hui; Hovhannisyan, Vladimir; Lin, Wei-Chou; Chen, Wei-Liang; Chiou, Ling-Ling; Huang, Guan-Tarn; Kim, Ki Hean; So, Peter T. C.; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2009-11-01

    Conventional diagnosis for hepatocellular carcinoma (HCC) is time consuming in sample preparation and deficient in quantitative examination. In this work, we developed multiphoton autofluorescence (MAF) microscopy as an effective and efficient tool in HCC diagnosis with qualitative imaging and quantitative measurement. We found that MAF imaging effectively identifies cellular architecture in the liver specimens. Our results also demonstrate the capability of using tissue quantitative parameters of multiphoton autofluorescence intensity ratio, the nuclear number density, and nuclear-cytoplasmic ratio for tumor discrimination. This approach has the potential in clinical diagnosis of HCC and the in vivo investigation of liver tumor development in animal models.

  13. Diagrammatic analysis of multiphoton processes in a ladder-type three-level atomic system

    SciTech Connect

    Noh, Heung-Ryoul; Moon, Han Seb

    2011-11-15

    We present a diagrammatic method for complete characterization of multiphoton processes in three-level atomic systems. By considering the interaction routes of the coupling and probe photons for a ladder-type, three-level, noncycling (or cycling) atomic system, we are able to completely discriminate between the pure one-photon and the pure two-photon resonance effects, and the effect of their combination in electromagnetically induced transparency (EIT) using our diagrammatic method. We show that the proposed diagrammatic method is very useful for the analysis of multiphoton processes in ladder-type EIT.

  14. The revival-collapse phenomenon in the quadrature field components of the two-mode multiphoton Jaynes-Cummings model

    E-print Network

    Faisal A A El-Orany

    2009-08-13

    In this paper we consider a system consisting of a two-level atom in an excited state interacting with two modes of a radiation field prepared initially in $l$-photon coherent states. This system is described by two-mode multiphoton (, i.e., $k_1, k_2$) Jaynes-Cummings model (JCM). For this system we investigate the occurrence of the revival-collapse phenomenon (RCP) in the evolution of the single-mode, two-mode, sum and difference quadrature squeezing. We show that there is a class of states for which all these types of squeezing exhibit RCP similar to that involved in the corresponding atomic inversion. Also we show numerically that the single-mode squeezing of the first mode for $(k_1,k_2)=(3,1)$ provides RCP similar to that of the atomic inversion of the case $(k_1,k_2)=(1,1)$, however, sum and difference squeezing give partial information on that case. Moreover, we show that single-mode, two-mode and sum squeezing for the case $(k_1,k_2)=(2,2)$ provide information on the atomic inversion of the single-mode two-photon JCM. We derive the rescaled squeezing factors giving accurate information on the atomic inversion for all cases. The consequences of these results are that the homodyne and heterodyne detectors can be used to detect the RCP for the two-mode JCM.

  15. Assessment of liver steatosis and fibrosis in rats using integrated coherent anti-Stokes Raman scattering and multiphoton imaging technique

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Lu, Fake; Zheng, Wei; Xu, Shuoyu; Tai, Dean; Yu, Hanry; Huang, Zhiwei

    2011-11-01

    We report the implementation of a unique integrated coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and two-photon excitation fluorescence (TPEF) microscopy imaging technique developed for label-free monitoring of the progression of liver steatosis and fibrosis generated in a bile duct ligation (BDL) rat model. Among the 21 adult rats used in this study, 18 rats were performed with BDL surgery and sacrificed each week from weeks 1 to 6 (n = 3 per week), respectively; whereas 3 rats as control were sacrificed at week 0. Colocalized imaging of the aggregated hepatic fats, collagen fibrils, and hepatocyte morphologies in liver tissue is realized by using the integrated CARS, SHG, and TPEF technique. The results show that there are significant accumulations of hepatic lipid droplets and collagen fibrils associated with severe hepatocyte necrosis in BDL rat liver as compared to a normal liver tissue. The volume of normal hepatocytes keeps decreasing and the fiber collagen content in BDL rat liver follows a growing trend until week 6; whereas the hepatic fat content reaches a maximum in week 4 and then appears to stop growing in week 6, indicating that liver steatosis and fibrosis induced in a BDL rat liver model may develop at different rates. This work demonstrates that the integrated CARS and multiphoton microscopy imaging technique has the potential to provide an effective means for early diagnosis and detection of liver steatosis and fibrosis without labeling.

  16. Kinetic modeling of evolution of 3?+?1:Resonance enhanced multiphoton ionization plasma in argon at low pressures

    SciTech Connect

    Tholeti, Siva Sashank; Alexeenko, Alina A.; Shneider, Mikhail N.

    2014-06-15

    We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5?Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10?s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

  17. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments

    SciTech Connect

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo E-mail: xfzheng@mail.ahnu.edu.cn; Zheng, Xianfeng E-mail: xfzheng@mail.ahnu.edu.cn; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-15

    Compared to single ion/electron-optics for velocity-map imaging, a double-focusing lens assembly designed not only allows for mapping velocity imaging of photoelectrons but also allows for investigating the vibrational structure of the intermediate states of neutral species in resonance enhanced multiphoton ionization (REMPI) spectra. In this presentation, in order to record REMPI and photoelectron spectra separately, we have constructed a compact photoelectron velocity-map imaging (VMI) apparatus combined with an opposite linear Wiley-Mclaren time-of-flight mass spectrometer (TOFMS). A mass resolution (m/?m) of ?1300 for TOFMS and electron energy resolution (?E/E) of 2.4% for VMI have been achieved upon three-photon ionization of Xe atom at 258.00 nm laser wavelength. As a benchmark, in combination of one-color (1 + 1) REMPI and photoelectron imaging of benzene via 6{sup 1} and 6{sup 1}1{sup 1} vibronic levels in the S{sub 1} state, the vibrational structures of the cation and photoelectron angular anisotropy are unraveled. In addition, two-color (1 + 1?) REMPI and photoelectron imaging of aniline was used to complete the accurate measurement of ionization potential (62 271 ± 3 cm{sup ?1}). The results suggest that the apparatus is a powerful tool for studying photoionization dynamics in the photoelectron imaging using vibrational-state selected excitation to the intermediate states of neutrals based on REMPI technique.

  18. Multimodal imaging of living cells with multiplex coherent anti-stokes raman scattering (CARS), third-order sum frequency generation (TSFG) and two-photon excitation fluorescence (TPEF) using a nanosecond white-light laser source.

    PubMed

    Segawa, Hiroki; Okuno, Masanari; Leproux, Philippe; Couderc, Vincent; Ozawa, Takeaki; Kano, Hideaki

    2015-01-01

    The subnanosecond "white-light laser" source has been applied to multimodal, multiphoton, and multiplex spectroscopic imaging (M(3) spectroscopic imaging) with coherent anti-Stokes Raman scattering (CARS), third-order sum frequency generation (TSFG), and two-photon excitation fluorescence (TPEF). As the proof-of-principle experiment, we performed simultaneous imaging of polystyrene beads with TSFG and TPEF. This technique is then applied to live cell imaging. Mouse L929 fibroblastic cells are clearly visualized by CARS, TSFG, and TPEF processes. M(3) spectroscopic imaging provides various and unique cellular information with different image contrast based on each multiphoton process. PMID:25864673

  19. Multiphoton-scattering theory and generalized master equations

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Chang, Darrick E.; Cirac, J. Ignacio

    2015-11-01

    We develop a scattering theory to investigate the multiphoton transmission in a one-dimensional waveguide in the presence of quantum emitters. It is based on a path integral formalism, uses displacement transformations, and does not require the Markov approximation. We obtain the full time evolution of the global system, including the emitters and the photonic field. Our theory allows us to compute the transition amplitude between arbitrary initial and final states, as well as the S matrix of the asymptotic in and out states. For the case of few incident photons in the waveguide, we also rederive a generalized master equation in the Markov limit. We compare the predictions of the developed scattering theory and that with the Markov approximation. We illustrate our methods with five examples of few-photon scattering: (i) by a two-level emitter, (ii) in the Jaynes-Cummings model; (iii) by an array of two-level emitters; (iv) by a two-level emitter in the half-end waveguide; and (v) by an array of atoms coupled to Rydberg levels. In the first two, we show the application of the scattering theory in the photon scattering by a single emitter, and examine the correctness of our theory with the well-known results. In the third example, we analyze the condition of the Markov approximation for the photon scattering in the array of emitters. In the fourth one, we show how a quantum emitter can generate entanglement of outgoing photons. Finally, we highlight the interplay between the phenomenon of electromagnetic-induced transparency and the Rydberg interaction, and show how this results in a rich variety of possibilities in the quantum statistics of the scattering photons.

  20. Multi-photon Scattering Theory and Generalized Master Equations

    E-print Network

    Tao Shi; Darrick E. Chang; J. Ignacio Cirac

    2015-07-30

    We develop a scattering theory to investigate the multi-photon transmission in a one-dimensional waveguide in the presence of quantum emitters. It is based on a path integral formalism, uses displacement transformations, and does not require the Markov approximation. We obtain the full time-evolution of the global system, including the emitters and the photonic field. Our theory allows us to compute the transition amplitude between arbitrary initial and final states, as well as the S-matrix of the asymptotic in- and out- states. For the case of few incident photons in the waveguide, we also re-derive a generalized master equation in the Markov limit. We compare the predictions of the developed scattering theory and that with the Markov approximation. We illustrate our methods with five examples of few-photon scattering: (i) by a two-level emitter, (ii) in the Jaynes-Cummings model; (iii) by an array of two-level emitters; (iv) by a two-level emitter in the half-end waveguide; (v) by an array of atoms coupled to Rydberg levels. In the first two, we show the application of the scattering theory in the photon scattering by a single emitter, and examine the correctness of our theory with the well-known results. In the third example, we analyze the condition of the Markov approximation for the photon scattering in the array of emitters. In the forth one, we show how a quantum emitter can generate entanglement of out-going photons. Finally, we highlight the interplay between the phenomenon of electromagnetic-induced transparency and the Rydberg interaction, and show how this results in a rich variety of possibilities in the quantum statistics of the scattering photons.

  1. Infrared spectroscopy to probe structure and dynamics in metal ion-molecule complexes

    NASA Astrophysics Data System (ADS)

    Duncan, Michael A.

    Vibrational spectroscopy measurements are described for mass-selected metal cation-molecular complexes using the technique of infrared resonance-enhanced photodissociation (REPD) spectroscopy. We discuss the mechanism of the REPD process in the infrared and how multiphoton techniques or rare gas tagging can be employed to facilitate dissociation processes in strongly bound complexes. Spectra are reported for Fe+(CO2)n complexes that demonstrate the formation of coordination spheres around the metal cation and for Mg+(CO2)n complexes, where the interaction with theory makes it possible to obtain structures for small clusters. Both of these studies investigate the asymmetric stretch region of CO2. Ni+(C

  2. An infrared journey

    NASA Astrophysics Data System (ADS)

    Kinch, Michael A.

    2015-06-01

    Infrared focal plane array technology has evolved dramatically over the last 50 years. The author has been privileged to participate in this remarkable evolution, working totally within the confines of one of the most significant and remaining US players in the focal plane game, namely Texas Instruments, later to become DRS Technologies. This presentation describes a journey from the Common Module through second and third generation infrared systems in the USA up to the exciting developments of the present day ultra-small pixel technology. It represents an attempt to detail both the technology development of the time together with some of its associated drama as viewed from the author's particular perspective. Thoughts on the lessons learned from this journey and their possible impact on future technology development will be discussed.

  3. Nonlinear effects in infrared action spectroscopy of silicon and vanadium oxide clusters: experiment and kinetic modeling.

    PubMed

    Calvo, Florent; Li, Yejun; Kiawi, Denis M; Bakker, Joost M; Parneix, Pascal; Janssens, Ewald

    2015-10-21

    For structural assignment of gas phase compounds, infrared action spectra are usually compared to computed linear absorption spectra. However, action spectroscopy is highly nonlinear owing to the necessary transfer of the excitation energy and its subsequent redistribution leading to statistical ionization or dissociation. Here, we examine by joint experiment and dedicated modeling how such nonlinear effects affect the spectroscopic features in the case of selected inorganic clusters. Vibrational spectra of neutral silicon clusters are recorded by tunable IR-UV two-color ionization while IR spectra for cationic vanadium oxide clusters are obtained by IR multiphoton absorption followed by dissociation of the bare cluster or of its complex with Xe. Our kinetic modeling accounts for vibrational anharmonicities, for the laser interaction through photon absorption and stimulated emission rates, as well as for the relevant ionization or dissociation rates, all based on input parameters from quantum chemical calculations. Comparison of the measured and calculated spectra indicates an overall agreement as far as trends are concerned, except for the photodissociation of the V3O7(+)-Xe messenger complex, for which anharmonicities are too large and poorly captured by the perturbative anharmonic model. In all systems studied, nonlinear effects are essentially manifested by variations in the intensities as well as spectral broadenings. Differences in some band positions originate from inaccuracies of the quantum chemical data rather than specific nonlinear effects. The simulations further yield information on the average number of photons absorbed, which is otherwise unaccessible information: several to several tens of photons need to be absorbed to observe a band through dissociation, while three to five photons can be sufficient for detection of a band via IR-UV ionization. PMID:26208251

  4. MULTI-PHOTON POLYMERIZATION OF WAVEGUIDE STRUCTURES WITHIN 3D PHOTONIC CRYSTALS

    E-print Network

    Braun, Paul

    demonstrate the use of a laser scanning confocal microscope (LSCM) for direct pattern generation multi-photon polymerization systems, and selected two of which appear to have great promise for defined was obtained. The colloidal crystal was then slightly sintered at 300o C to increase the mechanical stability

  5. Multi-photon transitions and Rabi resonance in continuous wave EPR.

    PubMed

    Saiko, Alexander P; Fedaruk, Ryhor; Markevich, Siarhei A

    2015-10-01

    The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines. PMID:26295168

  6. Multi-photon transitions and Rabi resonance in continuous wave EPR

    NASA Astrophysics Data System (ADS)

    Saiko, Alexander P.; Fedaruk, Ryhor; Markevich, Siarhei A.

    2015-10-01

    The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines.

  7. Multiphoton autofluorescence and second-harmonic generation diagnosis of hepatocellular carcinoma

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Sun, Tzu-Lin; Yang, Chuen-Huei; Hovhannisyan, Vladimir A.; Lin, Wei-Chou; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2008-02-01

    By using two-photon autofluorescence (TPAF) and second harmonics generation (SHG), we imaged hepatocellular carcinoma (HCC) biopsies from the human patients and compared them with the conventional histological biopsies. We found that multiphoton microscopy may be used to obtain label-free images of liver tissues and may be developed into an effective diagnostic tool for liver diseases.

  8. MULTIPHOTON ENTANGLEMENT Mohamed Bourennane1, Manfred Eibl1, Sascha Gaertner1,

    E-print Network

    Weinfurter, Harald

    Multiphoton entanglement is the basis of many quantum communication schemes, quantum cryptographic protocols for implementations of quantum communication schemes, quantum cryptographic protocols, and for fundamental tests, and fundamental tests of quantum theory. Spontaneous parametric down-conversion is the most effective source

  9. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    NASA Astrophysics Data System (ADS)

    dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [

    F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)
    ], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  10. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell'Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  11. Multiphoton Lithography of Nanocrystalline Platinum and Palladium for Site-Specific Catalysis in 3D Microenvironments

    E-print Network

    Brinker, C. Jeffrey

    Multiphoton Lithography of Nanocrystalline Platinum and Palladium for Site-Specific Catalysis in 3D nanostructured platinum and palladium within 3D microscale structures or fluidic environments is important a straightforward procedure to fabricate microscale patterns of nanocrystalline platinum and palladium using

  12. Multiphoton amplification processes and quantum-path interferences in a coherently driven atomic vapor

    SciTech Connect

    Fernandez-Soler, J.J.; Font, J.L.; Vilaseca, R.; Gauthier, Daniel J.; Kul'minskii, A.

    2003-10-01

    We develop a theoretical model of two-photon amplification in laser-driven potassium atoms and use it to analyze the recent experiments reported by Pfister et al. [Phys. Rev. A 60, R4249 (1999)]. The model takes into account most of the essential factors influencing the amplification process, including the atomic hyperfine structure (which makes multiphoton emission possible) and the simultaneous interaction with intense drive and probe beams with arbitrary detunings. We determine the origin and analyze the properties of different multiphoton gain resonances that appear in the light-matter interaction. In particular, the influence of the drive and probe field amplitudes and detunings on the strength and frequency of the two-photon amplification resonance is studied in detail, showing clearly the differences with respect to the behavior of single-photon or other multiphoton amplification processes. In addition, we investigate interferences between different quantum pathways originating from the hyperfine structure and determine the conditions under which they can enhance or suppress multiphoton resonances. The predictions of the model are in good agreement with the observations, indicating that it can be used to understand recent experiments on two-photon lasing reported by Pfister et al. [Phys. Rev. Lett. 86, 4512 (2001)].

  13. Multiphoton ionization photoelectron spectroscopy of phenol: Vibrational frequencies and harmonic force field for the 281 cation

    E-print Network

    Multiphoton ionization photoelectron spectroscopy of phenol: Vibrational frequencies and harmonic 94305 (Recieved 1 February 1985; accepted 14 March 1985) A molecular beam of phenol, cooled vibrational frequencies for the 2BI phenol-h6cation and ten vibrational frequencies for phenol-d5. Of these

  14. Remote sensing by infrared heterodyne spectroscopy

    NASA Technical Reports Server (NTRS)

    Kostiuk, T.; Mumma, M. J.

    1983-01-01

    The use of infrared heterodyne spectrocopy for the study of planetary atmospheres is discussed. Infrared heterodyne spectroscopy provides a convenient and sensitive method for measuring the true intensity profiles of atmospheric spectral lines. Application of radiative transfer theory to measured lineshapes can then permit the study of molecular abundances, temperatures, total pressures, excitation conditions, and dynamics of the regions of line formation. The theory of formation of atmospheric spectral lines and the retrieval of the information contained in these molecular lines is illustrated. Notable successes of such retrievals from infrared heterodyne measurements on Venus, Mars, Jupiter and the Earth are given. A discussion of developments in infrared heterodyne technology is also presented.

  15. Infrared Measurement

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A Jet Propulsion Laboratory Technical Support Package (TSP) describing a technique for processing data from an infrared radiometer assisted a manufacturer of laminates for printed circuit boards. To reduce emissions and lower the cost of producing prepreg (a continuous glass cloth, or web, impregnated with epoxy resin and partially cured by applying heat), Norplex Oak switched to infrared treating towers. The TSP confirmed the company's computer prediction of heat flux patterns, provided information that allowed the company to modify infrared treaters for consistency, and furnished a basis for development of optimal heater placements. The treaters are now successfully operating at increased speeds with improved product consistency.

  16. Excited baryons as experimental probes of the quark mass

    E-print Network

    Felipe J. Llanes-Estrada; Pedro Bicudo; Marco Cardoso; Tim Van Cauteren

    2009-05-26

    We observe that excited hadrons provide an opportunity to probe from experiment the power-law running of the quark mass in the mid infrared, while the condition m(k)excitations of the Delta baryons, analogous to the yrast states in nuclei. Such states are accessible at current experimental facilities such as ELSA and Jlab.

  17. Infrared monitoring of the Space Station environment

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor; Jennings, Donald E.; Mumma, Michael J.

    1988-01-01

    The measurement and monitoring of infrared emission in the environment of the Space Station has a twofold importance - for the study of the phenomena itself and as an aid in planning and interpreting Station based infrared experiments. Spectral measurements of the infrared component of the spacecraft glow will, along with measurements in other spectral regions, provide data necessary to fully understand and model the physical and chemical processes producing these emissions. The monitoring of the intensity of these emissions will provide background limits for Space Station based infrared experiments and permit the determination of optimum instrument placement and pointing direction. Continuous monitoring of temporal changes in the background radiation (glow) will also permit better interpretation of Station-based infrared earth sensing and astronomical observations. The primary processes producing infrared emissions in the Space Station environment are: (1) Gas phase excitations of Station generated molecules ( e.g., CO2, H2O, organics...) by collisions with the ambient flux of mainly O and N2. Molecular excitations and generation of new species by collisions of ambient molecules with Station surfaces. They provide a list of resulting species, transition energies, excitation cross sections and relevant time constants. The modeled spectrum of the excited species occurs primarily at wavelengths shorter than 8 micrometer. Emissions at longer wavelengths may become important during rocket firing or in the presence of dust.

  18. Why Infrared?

    ERIC Educational Resources Information Center

    Harris, J. R.

    1973-01-01

    Discusses applications of techniques developed for the remote sensing of infrared radiation. In addition to military applications, remote sensing has become important in collecting environmental data and detecting ecological problems. (JR)

  19. Seeing Infrared.

    ERIC Educational Resources Information Center

    Mooney, Donald

    1992-01-01

    Provides directions for building a comparatively inexpensive device that detects and displays images of infrared light sources. Includes typical costs for the components, an artist's sketch of the finished product, and suggestions for adjustments and image recordings. (JJK)

  20. Infrared Imaging

    NASA Astrophysics Data System (ADS)

    Danchi, W.; Lawson, P.; Absil, O.; Akeson, R.; Bally, J.; Barry, R.; Beichman, C.; Belu, A.; Boyce, M.; Breckinridge, J.; Burrows, A.; Chen, C.; Cole, D.; Crisp, D.; Danner, R.; Deroo, P.; Coudé du Foresto, V.; Defrère, D.; Ebbets, D.; Falkowski, P.; Gappinger, R.; Haugabook, I.; Hanot, C.; Henning, T.; Hinz, P.; Hollis, J.; Hunyadi, S.; Hyland, D.; Johnston, K.; Kaltenegger, L.; Kasting, J.; Kenworthy, M.; Ksendzov, A.; Lane, B.; Laughlin, G.; Lay, O.; Liseau, R.; Lopez, B.; Millan-Gabet, R.; Martin, S.; Mawet, D.; Mennesson, B.; Monnier, J.; Murakami, N.; Noecker, C.; Nishikawa, J.; Pesesen, M.; Peters, R.; Quillen, A.; Ragland, S.; Rinehart, S.; Rottgering, H.; Scharf, D.; Serabyn, G.; Tamura, M.; Tehrani, M.; Traub, W.; Unwin, S.; Wilner, D.; Woilliez, J.; Woolf, N.; Zhao, M.

    2009-03-01

    A mid-infrared mission would enable the detection of biosignatures of Earth-like exoplanets around more than 150 nearby stars. The mid-infrared spectral region is attractive for characterizing exoplanets because contrast with the parent star brightness is more favorable than in the visible (10 million vs. 10 billion), and because mid-infrared light probes deep into a planet's troposphere. Furthermore, the mid-infrared offers access to several strong molecular features that are key signs of life, and also provides a measure of the effective temperature and size of a planet. Taken together, an infrared mission plus a visible one would provide a nearly full picture of a planet, including signs of life; with a measure of mass from an astrometric mission, we would have a virtually complete picture. A small infrared mission would have several telescopes that are rigidly connected, with a science return from the detection and characterization of super-Earth sized to larger planets near the HZ, plus a direct measure of the exozodi brightness in the HZ. In a large infrared mission, with formation-flying telescopes, planets from an Earth-twin and upwards in mass could be detected and characterized, as well as the exozodi. If proceeded by an astrometric mission, the detection phase could be skipped and the mission devoted to characterization, as in the visible case; lacking an astrometric mission, an infrared one could proceed alone, as was discussed for a visible coronograph, and with similar caveats. The technology needed for a large formation-flying mission is similar to that for a small connected-element one (e.g., cryogenics and detectors), with the addition of formationflying technology. The technology is now in hand to implement a probe-scale mission; starlight suppression has even been demonstrated to meet the requirements of a flagship mission. However, additional development of formation-flying technology is needed, particularly in-space testing of sensors and guidance, navigation, and control algorithms.

  1. Light emission of very low density hydrogen excited by an extremely hot light source; applications in astrophysics

    E-print Network

    Jacques Moret-Bailly

    2008-07-19

    Stromgren studied the action of an extremely hot source on a diluted pure hydrogen cloud; a very ionized, spherical hydrogen plasma surrounded by neutral atomic hydrogen is formed. A relatively thin intermediate, partially ionized, hydrogen shell, is cooled by the radiation of the atoms. Stromgren was unaware of that this plasma, similar to the plasma of a gas laser, can be superradiant at several eigen frequencies of atomic hydrogen; the superradiant rays emitted tangentially with the sphere appear resulting from a discontinuous ring because of the competition of optical modes. The superradiance intensely depopulates the excited levels, including the continuum of proton-electron collisions, by cascades of transitions combined into resonant multiphotonic transitions so that the gas is cooled brutally beyond the radius of the Stromgren sphere. The extreme brightness of the rays emitted by the source allows a multiphotonic non-resonant absorption leading in stationary states or the ionization continuum. This absorption combines with the superradiant emissions in a multiphotonic diffusion induced by the superradiant rays. Although its brightness remains higher than that of the superradiant rays, the source becomes invisible if it is observed through a small solid angle. The lines emitted inside the sphere are all the more weak as they arrive of an internal area, lower in atoms, and more reddened also by a parametric transfer of energy towards the thermal radiation catalyzed by excited atomic hydrogen present in the sphere only. The Stromgren sphere appears to help to simply explain the appearance and the spectrum of supernova 1987A.

  2. Floquet formulation for the investigation of multiphoton quantum interference in a superconducting qubit driven by a strong ac field

    E-print Network

    Son, Sang-Kil; Han, Siyuan; Chu, Shih-I

    2009-03-03

    We present a Floquet treatment of multiphoton quantum interference in a strongly driven superconducting flux qubit. The periodically time-dependent Schrödinger equation can be reduced to an equivalent time-independent infinite-dimensional Floquet...

  3. Infrared up-converting phosphors for bioassays.

    PubMed

    Corstjens, P L A M; Li, S; Zuiderwijk, M; Kardos, K; Abrams, W R; Niedbala, R S; Tanke, H J

    2005-04-01

    The development of up-converting phosphor reporter particles has added a powerful tool to modern detection technologies. Carefully constructed phosphor reporters have core-shell structures with surface functional groups suitable for standard bio-conjugations. These reporters are chemically stable, possess the unique property of infrared up-conversion, and are readily detected. In contrast to conventional fluorescent reporters, up-converting phosphor particles do not bleach and allow permanent excitation with simultaneous signal integration. A large anti-Stokes shift (up to 500 nm) separates discrete emission peaks from the infrared excitation source. Along with the unmatched contrast in biological specimens due to the absence of autofluorescence upon infrared excitation, up-converting phosphor technology (UPT) has unique properties for highly-sensitive particle-based assays. The production and characteristics of UPT reporter particles as well as their application in various bioassays is reviewed. PMID:16441160

  4. Coherent control of multiphoton resonance dynamics in high-order-harmonic generation driven by two frequency-comb fields

    NASA Astrophysics Data System (ADS)

    Zhao, Di; Jiang, Chen-Wei; Li, Fu-li

    2015-10-01

    We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation (HHG) process driven by two frequency-comb fields with the carrier frequencies of fundamental and second harmonics, respectively. The many-mode Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and frequency-comb laser fields. The coupling of the weak second-harmonic control frequency-comb laser field promises more routes to coherently optimize the multiphoton resonance dynamics and HHG power spectra. First, even-order harmonics are generated due to the coupling of the second-harmonic frequency-comb field. Second, the HHG power spectra can be greatly enhanced via multiphoton resonance, which can be achieved by tuning the carrier-envelope-phase (CEP) shifts and the peak intensities of both frequency-comb fields. Furthermore, besides the multiphoton transitions involving only fundamental-harmonic photons, additional multiphoton transitions involving both fundamental- and second-harmonic photons occur, resulting in the generation of combs with frequencies dependent on CEP shifts of both fields. Different multiphoton transition paths can interfere with each other when the two CEP shifts are matching, and the interference of paths allows one to coherently control the HHG power spectra by varying the relative phase between the fields.

  5. Resonance enhanced multiphoton and single-photon ionization of molecules and molecular fragments. Final report, May 1993--April 1997

    SciTech Connect

    McKoy, V.

    1998-09-01

    Resonance enhanced multiphoton ionization (REMPI) utilizes pulsed laser radiation to prepare a molecule in an excited state via absorption of one or more photons and to subsequently ionize that level before it decays. A remarkable feature of REMPI is that the very narrow bandwidth of laser radiation makes it possible to select a specific rotational level in the initial (ground) state and to prepare the excited state of interest in a single rotational level. Thus, by suitable choice of the excitation step, it is possible to selectively ionize a species that may be present. The key objective of the effort is to carry out quantitative studies of REMPI of molecules and molecular fragments, as well as of single-photon ionization of these species by coherent VUV radiation, in order to provide a robust description of significant spectral features of interest in related experiments and needed insight into the underlying dynamics of these spectra. A major focus of the effort is joint theoretical and experimental studies of these ion rotational distributions which are being widely studied by the zero-kinetic-energy (ZEKE) technique. This technique, which is based on the detection of photoelectrons resulting from pulsed-field ionization of very high Rydberg states lying just below an ion threshold, makes it possible to obtain cation distributions with subwavenumber resolution. The unprecedented resolution of this ZEKE technique is opening up entirely new vistas in studies of photoionization dynamics, ion spectroscopy, and state-selected ion-molecule reactions. Emerging applications built on the ultra-high resolution of this technique include its use for accurate determination of thermochemically important ionization energies, for characterization of ion rovibrational level structure of large organic molecules, of elemental clusters, and of weakly bound molecular complexes, for probing reactive fragments, and for pump-probe photoelectron studies of wavepacket dynamics. This surge of experimental activity in ultra-high resolution studies of molecular photoelectron spectra continues to raise new theoretical challenges and has provided the stimulus for several of the collaborations with experimental groups in North America and Europe.

  6. FAR-INFRARED SPECTROSCOPY OF CATIONIC POLYCYCLIC AROMATIC HYDROCARBONS: ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY OF PENTACENE VAPORIZED FROM LASER DESORPTION

    SciTech Connect

    Zhang Jie; Han Fangyuan; Pei Linsen; Kong Wei; Li Aigen

    2010-05-20

    The distinctive set of infrared (IR) emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are ubiquitously seen in a wide variety of astrophysical environments. They are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. However, not a single PAH species has yet been identified in space, as the mid-IR vibrational bands are mostly representative of functional groups and thus do not allow one to fingerprint individual PAH molecules. In contrast, the far-IR (FIR) bands are sensitive to the skeletal characteristics of a molecule, hence they are important for chemical identification of unknown species. With an aim to offer laboratory astrophysical data for the Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and similar future space missions, in this work we report neutral and cation FIR spectroscopy of pentacene (C{sub 22}H{sub 14}), a five-ring PAH molecule. We report three IR active modes of cationic pentacene at 53.3, 84.8, and 266 {mu}m that may be detectable by space missions such as the SAFARI instrument on board SPICA. In the experiment, pentacene is vaporized from a laser desorption source and cooled by a supersonic argon beam. We have obtained results from two-color resonantly enhanced multiphoton ionization and two-color zero kinetic energy photoelectron (ZEKE) spectroscopy. Several skeletal vibrational modes of the first electronically excited state of the neutral species and those of the cation are assigned, with the aid of ab initio and density functional calculations. Although ZEKE is governed by the Franck-Condon principle different from direct IR absorption or emission, vibronic coupling in the long ribbon-like molecule results in the observation of a few IR active modes. Within the experimental resolution of {approx}7 cm{sup -1}, the frequency values from our calculation agree with the experiment for the cation, but differ for the electronically excited intermediate state. Consequently, modeling of the intensity distribution is difficult and may require explicit inclusion of vibronic interactions.

  7. Examination of diagnostic features in multiphoton microscopy and optical coherence tomography images of ovarian tumorigenesis in a mouse model

    NASA Astrophysics Data System (ADS)

    Watson, Jennifer M.

    Ovarian cancer is a deadly disease owing to the non-specific symptoms and suspected rapid progression, leading to frequent late stage detection and poor prognosis. Medical imaging methods such as CT, MRI and ultrasound as well as serum testing for cancer markers have had extremely poor performance for early disease detection. Due to the poor performance of available screening methods, and the impracticality and ineffectiveness of taking tissue biopsies from the ovary, women at high risk for developing ovarian cancer are often advised to undergo prophylactic salpingo-oophorectomy. This surgery results in many side effects and is most often unnecessary since only a fraction of high risk women go on to develop ovarian cancer. Better understanding of the early development of ovarian cancer and characterization of morphological changes associated with early disease could lead to the development of an effective screening test for women at high risk. Optical imaging methods including optical coherence tomography (OCT) and multiphoton microscopy (MPM) are excellent tools for studying disease progression owing to the high resolution and depth sectioning capabilities. Further, these techniques are excellent for optical biopsy because they can image in situ non-destructively. In the studies described in this dissertation OCT and MPM are used to identify cellular and tissue morphological changes associated with early tumor development in a mouse model of ovarian cancer. This work is organized into three specific aims. The first aim is to use the images from the MPM phenomenon of second harmonic generation to quantitatively examine the morphological differences in collagen structure in normal mouse ovarian tissue and mouse ovarian tumors. The second aim is to examine the differences in endogenous two-photon excited fluorescence in normal mouse ovarian tissue and mouse ovarian tumors. The third and final aim is to identify changes in ovarian microstructure resulting from early disease development by imaging animals in vivo at three time points during a long-term survival study.

  8. Multiphoton Microscopy of Prostate and Periprostatic Neural Tissue: A Promising Imaging Technique for Improving Nerve-Sparing Prostatectomy

    PubMed Central

    Yadav, Rajiv; Mukherjee, Sushmita; Hermen, Michael; Tan, Gerald; Maxfield, Frederick R.; Webb, Watt W.

    2009-01-01

    Abstract Background and Purpose Various imaging modalities are under investigation for real-time tissue imaging of periprostatic nerves with the idea of improving the results of nerve-sparing radical prostatectomy. We explored multiphoton microscopy (MPM) for real-time tissue imaging of the prostate and periprostatic neural tissue in a male Sprague-Dawley rat model. The unique advantage of this technique is the acquisition of high-resolution images without necessitating any extrinsic labeling agent and with minimal phototoxic effect on tissue. Materials and Methods The prostate and cavernous nerves were surgically excised from male Sprague-Dawley rats. The imaging was carried out using intrinsic fluorescence and scattering properties of the tissues without any exogenous dye or contrast agent. A custom-built MPM, consisting of an Olympus BX61WI upright frame and a modified MRC 1024 scanhead, was used. A femtosecond pulsed titanium/sapphire laser at 780-nm wavelength was used to excite the tissue; laser power under the objective was modulated via a Pockels cell. Second harmonic generation (SHG) signals were collected at 390 (±35?nm), and broadband autofluorescence was collected at 380 to 530?nm. The images obtained from SHG and from tissue fluorescence were then merged and color coded during postprocessing for better appreciation of details. The corresponding tissues were subjected to hematoxylin and eosin staining for histologic confirmation of the structures. Results High-resolution images of the prostate capsule, underlying acini, and individual cells outlining the glands were obtained at varying magnifications. MPM images of adipose tissue and the neural tissues were also obtained. Histologic confirmation and correlation of the prostate gland, fat, cavernous nerve, and major pelvic ganglion validated the findings of MPM. Conclusion Real-time imaging and microscopic resolution of prostate and periprostatic neural tissue using MPM is feasible without the need for any extrinsic labeling agents. Integration of this imaging modality with operative technique has the potential to improve the precision of nerve-sparing prostatectomy. PMID:19425823

  9. Infrared astronomy

    NASA Technical Reports Server (NTRS)

    Gillett, Frederick; Houck, James; Bally, John; Becklin, Eric; Brown, Robert Hamilton; Draine, Bruce; Frogel, Jay; Gatley, Ian; Gehrz, Robert; Hildebrand, Roger

    1991-01-01

    The decade of 1990's presents an opportunity to address fundamental astrophysical issues through observations at IR wavelengths made possible by technological and scientific advances during the last decade. The major elements of recommended program are: the Space Infrared Telescope Facility (SIRTF), the Stratospheric Observatory For Infrared Astronomy (SOFIA) and the IR Optimized 8-m Telescope (IRO), a detector and instrumentation program, the SubMilliMeter Mission (SMMM), the 2 Microns All Sky Survey (2MASS), a sound infrastructure, and technology development programs. Also presented are: perspective, science opportunities, technical overview, project recommendations, future directions, and infrastructure.

  10. Infrared Thermometer

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Diatek Corporation, San Diego, CA and the Jet Propulsion Lab developed the Diatek Model 7000 aural thermometer which weighs only eight ounces, and measures temperature in less than two seconds using infrared astronomy technology to measure the amount of infrared energy emitted by the eardrum (the same way temperature of stars and planets is measured). This method avoids contact with mucous membranes, virtually eliminating the possibility of cross infection, and permits temperature measurement of newborn, critically ill, or incapacitated patients. Diatek Corporation was purchased by Welch Allyn Inc. The Diatek Model 7000 is now marketed as SureTemp.

  11. Infrared QCD

    NASA Astrophysics Data System (ADS)

    Frasca, Marco

    We prove that Nambu-Jona-Lasinio model is an exact description of infrared Quantum ChromoDynamics (QCD) deriving it from QCD Lagrangian. The model we obtain is renormalizable and confining but, taking very small momenta fixes completely all the parameters of the Nambu-Jona-Lasinio model through those of QCD. The choice of the infrared propagator is done consistently with recent numerical results from lattice and Dyson-Schwinger equations for Yang-Mills theory. The model we get coincides, once the ultraviolet contribution is removed, with the one proposed by Langfeld, Kettner and Reinhardt [Nucl. Phys. A 608 (1996) 331].

  12. Infrared QCD

    E-print Network

    Marco Frasca

    2008-08-29

    We prove that Nambu-Jona-Lasinio model is an exact description of infrared QCD deriving it from QCD Lagrangian. The model we obtain is renormalizable and confining but, taking very small momenta fixes completely all the parameters of the Nambu-Jona-Lasinio model through those of QCD. The choice of the infrared propagator is done consistently with recent numerical results from lattice and Dyson-Schwinger equations for Yang-Mills theory. The model we get coincides, once the ultraviolet contribution is removed, with the one proposed by Langfeld, Kettner and Reinhardt [Nucl. Phys. A {\\bf 608}, 331 (1996)].

  13. High-fidelity spatially resolved multiphoton counting for quantum imaging applications

    E-print Network

    Radoslaw Chrapkiewicz; Wojciech Wasilewski; Konrad Banaszek

    2014-05-17

    We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for non-linearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of Mandel and Fano parameters in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one photon per an event area, substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution.

  14. High-fidelity spatially resolved multiphoton counting for quantum imaging applications

    E-print Network

    Chrapkiewicz, Radoslaw; Banaszek, Konrad

    2015-01-01

    We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for non-linearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of Mandel and Fano parameters in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one photon per an event area, substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution.

  15. Label-free identification of intestinal metaplasia in the stomach using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Wu, G.; Wei, J.; Zheng, Z.; Ye, J.; Zeng, S.

    2014-06-01

    The early diagnosis of intestinal metaplasia (IM) in the stomach together with effective therapeutic interventions is crucial to reducing the mortality-rates of the patients associated with gastric cancer. However, it is challenging during conventional white-light endoscopy, and histological analysis remains the ‘gold standard’ for the final diagnosis. Here, we describe a label-free imaging method, multiphoton microscopy (MPM), for the identification of IM in the stomach. It was found that multiphoton imaging provides cellular and subcellular details to the identification of IM from normal gastric tissues. In particular, there is significant difference in the population density of goblet cells between normal and IM gastric tissues, providing substantial potential to become a quantitative intrinsic marker for in vivo clinical diagnosis of early gastric lesions. To our knowledge, this is the first demonstration of the potential of MPM for the identification of IM.

  16. Quantum teleportation and entanglement swapping of matter qubits with coherent multiphoton states

    E-print Network

    J. M. Torres; J. Z. Bernád; G. Alber

    2014-07-03

    Protocols for probabilistic entanglement-assisted quantum teleportation and for entanglement swapping of material qubits are presented. They are based on a protocol for postselective Bell-state projection which is capable of projecting two material qubits onto a Bell state with the help of ancillary coherent multiphoton states and postselection by balanced homodyne photodetection. Provided this photonic postselection is successful we explore the theoretical possibilities of realizing unit fidelity quantum teleportation and entanglement swapping with $25\\%$ success probability. This photon-assisted Bell projection is generated by coupling almost resonantly the two material qubits to single modes of the radiation field in two separate cavities in a Ramsey-type interaction sequence and by measuring the emerged field states in a balanced homodyne detection scenario. As these quantum protocols require basic tools of quantum state engineering of coherent multiphoton states and balanced homodyne photodetection they may offer interesting perspectives in particular for current quantum optical applications in quantum information processing.

  17. Multiphoton single ionization of two-electron systems in intense laser fields

    SciTech Connect

    Bhattacharyya, S.; Mukherjee, Mahua; Mazumder, Mina; Chakrabarti, J.; Faisal, F. H. M.

    2009-07-15

    Multiphoton single-ionization of a two-electron system (He and He-like ions) in intense circularly polarized laser field is reported in a relativistic field theoretic method. Coulomb-correction factor is introduced to estimate the effect of the Coulomb field of the residual ion on the rate. Antisymmetric wave function is considered both in the initial and in the final state. The spin-specific currents are calculated. Angular asymmetry in current generation is noted with the change in the spin direction of the ionized electron. Coulomb-corrected relativistic-result for total rate is compared with the Coulomb-corrected nonrelativistic KFR rate. At the high-intensity regime nonrelativistic rate overestimates the relativistic rate. Formation of orthopositronium and parapositronium from positronium negative ion by multiphoton ionization is discussed.

  18. In vitro imaging of embryonic stem cells using multiphoton luminescence of gold nanoparticles.

    PubMed

    Nagesha, D; Laevsky, G S; Lampton, P; Banyal, R; Warner, C; DiMarzio, C; Sridhar, S

    2007-01-01

    Recent advances in nonlinear optical techniques and materials such as quantum wells, nanowires and noble-metal nanoparticles have led to advances in cellular imaging wherein various nanoparticles have been shown to improve both in vitro and in vivo visualization. In this paper, we demonstrate in vitro imaging using multi-photon photoluminescence of gold nanoparticles from two different cell types Dictyostelium discoideum and mouse embryonic stem cells. By observing nanoparticles we show that embryonic stem cells maintained their ability to proliferate for several passages while grown in the presence of gold nanoparticles. The advantages of multi-photon luminescence using gold nanoparticles have important implications for use in stem cell proliferation experiments and in vitro experiments to monitor differentiation. PMID:18203448

  19. In vitro imaging of embryonic stem cells using multiphoton luminescence of gold nanoparticles

    PubMed Central

    Nagesha, D; Laevsky, GS; Lampton, P; Banyal, R; Warner, C; DiMarzio, C; Sridhar, S

    2007-01-01

    Recent advances in nonlinear optical techniques and materials such as quantum wells, nanowires and noble-metal nanoparticles have led to advances in cellular imaging wherein various nanoparticles have been shown to improve both in vitro and in vivo visualization. In this paper, we demonstrate in vitro imaging using multi-photon photoluminescence of gold nanoparticles from two different cell types – Dictyostelium discoideum and mouse embryonic stem cells. By observing nanoparticles we show that embryonic stem cells maintained their ability to proliferate for several passages while grown in the presence of gold nanoparticles. The advantages of multi-photon luminescence using gold nanoparticles have important implications for use in stem cell proliferation experiments and in vitro experiments to monitor differentiation. PMID:18203448

  20. Laser-assisted ion-atom collisions: Plateau, cutoff, and multiphoton peaks

    SciTech Connect

    Ciappina, Marcelo F.; Madsen, Lars Bojer

    2008-02-15

    We study ionization in laser-assisted high-energy nonrelativistic ion-atom collisions and show that the low-energy angular differential electron spectrum may be enhanced by five orders of magnitude by an external field of strength less than 1/100 of the atomic field. With increasing strength of the assisting field, the energy spectrum develops a plateau with a characteristic cutoff. In the plateau region we predict distinct multiphoton peaks separated by the photon energy of the assisting field. In the present laser-assisted continuum-distorted-wave eikonal-initial-state theory, this effect may be related to the dynamics in the two-body electron-projectile subsystem. The laser-assisted distorted wave Born and first Born approximation do not account for the phase-distortion of the target electron by the incoming projectile and consequently the associated plateau, cutoff, and multiphoton features are not predicted by these latter theories.

  1. Vibrational noise removal method for the multi-photon interferometer of an optical loop system

    NASA Astrophysics Data System (ADS)

    Kim, Bongjune; Kang, Hoonsoo

    2015-04-01

    Multi-photon interference effects of the optical loop in a double-?/V system aid coherent photon control, especially all-optical switching between single photons. In the multi-photon interference, phase fluctuations induced by the mechanical vibration of the optical components should be removed to observe the high fidelity of photon controls. We solved this problem by overlapping coupling and probe beams that have opposite phase shifts in the optical loop system to cancel out phase fluctuation induced by mechanical vibration. We used two independent laser sources to generate two pairs of coupling-probe fields that are resonant on a double-? system. The removal of vibrational phase fluctuation was confirmed by comparison with a normal phase-dependent light-switching experiment.

  2. Multiphoton cascade absorption in single molecule fluorescence saturation spectroscopy.

    PubMed

    Winckler, Pascale; Jaffiol, Rodolphe

    2013-05-01

    Saturation spectroscopy is a relevant method to investigate photophysical parameters of single fluorescent molecules. Nevertheless, the impact of a gradual increase, over a broad range, of the laser excitation on the intramolecular dynamics is not completely understood, particularly concerning their fluorescence emission (the so-called brightness). Thus, we propose a comprehensive theoretical and experimental study to interpret the unexpected evolution of the brightness with the laser power taking into account the cascade absorption of two and three photons. Furthermore, we highlight the key role played by the confocal observation volume in fluorescence saturation spectroscopy of single molecules in solution. PMID:23521543

  3. REMOTE SENSING OF OZONE USING AN INFRARED DIFFERENTIAL ABSORPTION SYSTEM

    EPA Science Inventory

    A prototype airborne downlooking infrared differential absorption system using CO2 TEA (transverse excited atmospheric) lasers is described. The system uses two wavelengths and topographic reflection to measure the integrated column concentration of ozone between the laser source...

  4. Stimulated emission of two photons in parametric amplification and its interpretation as multi-photon interference

    E-print Network

    F. W. Sun; B. H. Liu; Y. X. Gong; Y. F. Huang; Z. Y. Ou; G. C. Guo

    2007-02-06

    Stimulated emission of two photons is observed experimentally in the parametric amplification process and is compared to a three-photon interference scheme. We find that the underlying physics of stimulated emission is simply the constructive interference due to photon indistinguishability. So the observed signal enhancement upon the input of photons is a result of multi-photon interference of the input photons and the otherwise spontaneously emitted photon from the amplifier.

  5. Atomic dynamics in single and multi-photon double ionization: An experimental comparison.

    PubMed

    Weber, T; Weckenbrock, M; Staudte, A; Hattass, M; Spielberger, L; Jagutzki, O; Mergel, V; Bocking, H; Urbasch, G; Giessen, H; Brauning, H; Cocke, C; Prior, M; Doerner, R

    2001-03-26

    We have used a multi-particle imaging technique (COLTRIMS) to observe the double ionization of rare gas atoms by multi-photon absorption of 800 nm (1.5 eV) femto-second laser pulses and by single photon absorption (synchrotron radiation). Both processes are mediated by electron correlation. We discuss similarities and differences in the three-body final state momentum distributions. PMID:19417829

  6. Multiphoton lasing in atomic potassium: Steady-state and dynamic behavior

    SciTech Connect

    Font, J. L.; Fernandez-Soler, J. J.; Vilaseca, R.; Gauthier, Daniel J.

    2005-12-15

    We show theoretically that it is possible to generate laser light based on two-photon and other high-order multiphoton processes when an atomic beam of optically driven potassium atoms crosses a high-finesse optical cavity. We use a rigorous model that takes into account all the atomic substates involved in the optical interactions and is valid for any drive and lasing field intensities. The polarizations of the drive and lasing fields are assumed to be fixed. Stable and unstable laser emission branches are obtained, which are represented as a function of cavity detuning and are analyzed in terms of the fundamental quantum processes yielding them. Closed-curve laser-emission profiles are obtained for multiphoton lasing based on processes involving more than one lasing photon. Two-photon laser emission branches show relatively long segments of stationary emission, combined in general with some segments of nonstationary emission, or with segments of mixture with three-photon emission processes. Rayleigh and hyper-Rayleigh processes can become simultaneously resonant, entailing in such case a large and fast transfer of population from the atomic initial ground sublevel to other ground sublevels with different z components of the total angular momentum. They could be useful in generating multiphoton correlated field states. In all cases the largest laser emission intensities are obtained from the highest-order processes, rather than the lowest. These results open the way to the understanding of experiments performed in the past years and suggest possibilities for more efficient and varied types of multiphoton laser operation.

  7. Multiphoton Process and Anomalous Potential of Cell Membrane by Laser Radiation

    NASA Technical Reports Server (NTRS)

    Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhar, Ping; Dong, Lifang

    1996-01-01

    In this paper, by the use of quantum biology and quantum optics, the laser induced potential variation of cell membrane has been studied. Theoretically, we have found a method of calculating the monophoton and multiphoton processes in the formation of the anomalous potential of cell membrane. In contrast with the experimental results, our numerical result is in the same order. Therefore, we have found the possibility of cancer caused by the laser induced anomalous cell potential.

  8. In vivo imaging of unstained tissues using a compact and flexible multiphoton microendoscope

    NASA Astrophysics Data System (ADS)

    Brown, Christopher M.; Rivera, David R.; Pavlova, Ina; Ouzounov, Dimitre G.; Williams, Wendy O.; Mohanan, Sunish; Webb, Watt W.; Xu, Chris

    2012-04-01

    We use a compact and flexible multiphoton microendoscope (MPME) to acquire in vivo images of unstained liver, kidney, and colon from an anesthetized rat. The device delivers femtosecond pulsed 800 nm light from the core of a raster-scanned dual-clad fiber (DCF), which is focused by a miniaturized gradient-index lens assembly into tissue. Intrinsic fluorescence and second-harmonic generation signal from the tissue is epi-collected through the core and inner clad of the same DCF. The MPME has a rigid distal tip of 3 mm in outer diameter and 4 cm in length. The image field-of-view measures 115 ?m by 115 ?m and was acquired at 4.1 frames/s with 75 mW illumination power at the sample. Organs were imaged after anesthetizing Sprague-Dawley rats with isofluorane gas, accessing tissues via a ventral-midline abdominal incision, and isolating the organs with tongue depressors. In vivo multiphoton images acquired from liver, kidney, and colon using this device show features similar to that of conventional histology slides, without motion artifact, in ~75% of imaged frames. To the best of our knowledge, this is the first demonstration of multiphoton imaging of unstained tissue from a live subject using a compact and flexible MPME device.

  9. Infrared telescope

    NASA Technical Reports Server (NTRS)

    Karr, G. R.; Hendricks, J. B.

    1985-01-01

    The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

  10. Infrared Thermometers

    ERIC Educational Resources Information Center

    Schaefers, John

    2006-01-01

    An infrared (IR) thermometer lab offers the opportunity to give science students a chance to measure surface temperatures, utilizing off-the-shelf technology. Potential areas of study include astronomy (exoplanets), electromagnetic spectrum, chemistry, evaporation rates, anatomy, crystal formation, and water or liquids. This article presents one…

  11. Time-Resolved Fluorescence Spectroscopy and Imaging of DNA Labeled with DAPI and Hoechst 33342 Using Three-Photon Excitation

    PubMed Central

    Lakowicz, Joseph R.; Gryczynski, Ignacy; Malak, Henryk; Schrader, Martin; Engelhardt, Peter; Kano, Hiroski; Hell, Stefan W.

    1997-01-01

    We examined the fluorescence spectral properties of the DNA stains DAPI (4?,6-diamidino-2-phenylindole, hydrochloride) and Hoechst 33342 (bis-benzimide, or 2,5?-bi-1H-benzimidazole2?-(4-ethoxyphenyl)-5-(4-methyl-1-piperazinyl)) with two-photon (2h?) and three-photon (3h?) excitation using femtosecond pulses from a Ti:sapphire laser from 830 to 885 nm. The mode of excitation of DAPI bound to DNA changed from two-photon at 830 nm to three-photon at 885 nm. In contrast, Hoechst 33342 displayed only two-photon excitation from 830 to 885 nm. DAPI-DNA displayed the same emission spectra and decay times for 2h? and 3h? excitation. Hoechst 33342-DNA displayed the same intensity decay for excitation at 830 and 885 nm. Both probes displayed higher anisotropies for multiphoton excitation as compared to one-photon excitation with ultraviolet wavelengths, and DAPI-DNA displays a higher anisotropy for 3h? at 885 nm than for 2h? at 830 nm. We used 970-nm excitation of DAPI-stained chromosomes to obtain the first three-dimensional images with three-photon excitation. Three-photon excitation of DAPI-stained chromosomes at 970 nm was demonstrated by the power dependence in the fluorescence microscope. ImagesFIGURE 10FIGURE 11FIGURE 12 PMID:9017187

  12. The Infrared Helix

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Helix nebula exhibits complex structure on the smallest visible scales. It is composed of gaseous shells and disks puffed out by a dying sun-like star.

    In this new image from NASA's Spitzer Space Telescope, 'cometary knots' show blue-green heads caused by excitation of their molecular material from shocks or ultraviolet radiation. The tails of the cometary knots appear redder due to being shielded from the central star's ultraviolet radiation and wind by the heads of the knots.

    This image was captured by the telescope's infrared array camera. The false color composite depicts wavelengths of 3.6 microns (blue), 4.5 microns (green), and 8.0 microns (red). The color saturation has been increased to intensify hues.

  13. Infrared laser system

    DOEpatents

    Cantrell, Cyrus D. (Richardson, TX); Carbone, Robert J. (Johnson City, TN); Cooper, Ralph (Hayward, CA)

    1982-01-01

    An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.

  14. Infrared floodlight

    DOEpatents

    Levin, Robert E. (S. Hamilton, MA); English, George J. (Reading, MA)

    1986-08-05

    An infrared floodlight assembly designed particularly for security purposes and including a heat-conducting housing, a lens secured to the housing to provide a closure therefor, and a floodlight located within (and surrounded by) the housing. The floodlight combines the use of a tungsten halogen light source and dichroic hot and cold mirrors for directing substantially only infrared radiation toward the assembly's forward lens. Visible radiation is absorbed by the housing's interior wall(s) and, optionally, by a filter located between the floodlight and lens. An optional means may be used within the floodlight to reflect all forward radiation back toward the paraboloidal hot mirror or, alternatively, to reflect only visible radiation in this direction. The dichroic hot and cold mirrors preferably each comprise a glass substrate having multiple layers of titanium dioxide and silicon dioxide thereon.

  15. In vivo multiphoton imaging of human skin: assessment of topical corticosteroid-induced epidermis atrophy and depigmentation

    NASA Astrophysics Data System (ADS)

    Ait El Madani, Hassan; Tancrède-Bohin, Emmanuelle; Bensussan, Armand; Colonna, Anne; Dupuy, Alain; Bagot, Martine; Pena, Ana-Maria

    2012-02-01

    Multiphoton microscopy has emerged in the past decade as a promising tool for noninvasive skin imaging. Our aim was to evaluate the potential of multiphoton microscopy to detect topical corticosteroids side effects within the epidermis and to provide new insights into their dynamics. Healthy volunteers were topically treated with clobetasol propionate on a small region of their forearms under overnight occlusion for three weeks. The treated region of each patient was investigated at D0, D7, D15, D22 (end of the treatment), and D60. Our study shows that multiphoton microscopy allows for the detection of corticoid-induced epidermis modifications: thinning of stratum corneum compactum and epidermis, decrease of keratinocytes size, and changes in their morphology from D7 to D22. We also show that multiphoton microscopy enables in vivo three-dimensional (3-D) quantitative assessment of melanin content. We observe that melanin density decreases during treatment and almost completely disappears at D22. Moreover, these alterations are reversible as they are no longer present at D60. Our study demonstrates that multiphoton microscopy is a convenient and powerful tool for noninvasive 3-D dynamical studies of skin integrity and pigmentation.

  16. Infrared retina

    DOEpatents

    Krishna, Sanjay (Albuquerque, NM); Hayat, Majeed M. (Albuquerque, NM); Tyo, J. Scott (Tucson, AZ); Jang, Woo-Yong (Albuquerque, NM)

    2011-12-06

    Exemplary embodiments provide an infrared (IR) retinal system and method for making and using the IR retinal system. The IR retinal system can include adaptive sensor elements, whose properties including, e.g., spectral response, signal-to-noise ratio, polarization, or amplitude can be tailored at pixel level by changing the applied bias voltage across the detector. "Color" imagery can be obtained from the IR retinal system by using a single focal plane array. The IR sensor elements can be spectrally, spatially and temporally adaptive using quantum-confined transitions in nanoscale quantum dots. The IR sensor elements can be used as building blocks of an infrared retina, similar to cones of human retina, and can be designed to work in the long-wave infrared portion of the electromagnetic spectrum ranging from about 8 .mu.m to about 12 .mu.m as well as the mid-wave portion ranging from about 3 .mu.m to about 5 .mu.m.

  17. Multiphoton Ionization and Dissociation of Diazirine: A Theoretical and Experimental Igor Fedorov, Lucas Koziol, Andrew K. Mollner, Anna I. Krylov,* and Hanna Reisler*

    E-print Network

    Reisler, Hanna

    Multiphoton Ionization and Dissociation of Diazirine: A Theoretical and Experimental Study IgorVed: February 26, 2009 Multiphoton ionization and dissociation processes in diazirine have been studied-lying 11 B2 (* r n) valence state, from which the strongest absorption is to the dissociative valence 11 A2

  18. Non-invasive manipulation of Drosophila behavior by two-photon excited red-activatable channelrhodopsin

    PubMed Central

    Hsiao, Po-Yen; Tsai, Chia-Lun; Chen, Ming-Chang; Lin, Yen-Yin; Yang, Shang-Da; Chiang, Ann-Shyn

    2015-01-01

    Scattering and absorption limit light penetration through inhomogeneous tissue. To reduce scattering, biochemists have shifted the wavelengths of excitation light for optogenetic actuators and fluorescent proteins to the orange-red range, while physicists have developed multiphoton technologies for deep tissue stimulation. We have built a rapid multiphoton spectroscopic screening system of genetically encoded red-activatable channelrhodopsin (ReaChR), and considered specific behaviors in transgenic Drosophila melanogaster as readouts to optimize the laser parameters for two-photon optogenetic activation. A wavelength-tunable optical parametric amplifier was adopted as the major light source for widefield two-photon excitation (TPE) of ReaChR. Our assays suggest that the optimized TPE wavelength of ReaChR is 1250 nm. Exploiting its capacity for optogenetic manipulation to induce macroscopic behavioral change, we realized rapid spectroscopic screening of genetically encoded effectors or indicators in vivo, and used modulation of ReaChR in the fly as a successful demonstration of such a system. PMID:26601000

  19. Non-invasive manipulation of Drosophila behavior by two-photon excited red-activatable channelrhodopsin.

    PubMed

    Hsiao, Po-Yen; Tsai, Chia-Lun; Chen, Ming-Chang; Lin, Yen-Yin; Yang, Shang-Da; Chiang, Ann-Shyn

    2015-11-01

    Scattering and absorption limit light penetration through inhomogeneous tissue. To reduce scattering, biochemists have shifted the wavelengths of excitation light for optogenetic actuators and fluorescent proteins to the orange-red range, while physicists have developed multiphoton technologies for deep tissue stimulation. We have built a rapid multiphoton spectroscopic screening system of genetically encoded red-activatable channelrhodopsin (ReaChR), and considered specific behaviors in transgenic Drosophila melanogaster as readouts to optimize the laser parameters for two-photon optogenetic activation. A wavelength-tunable optical parametric amplifier was adopted as the major light source for widefield two-photon excitation (TPE) of ReaChR. Our assays suggest that the optimized TPE wavelength of ReaChR is 1250 nm. Exploiting its capacity for optogenetic manipulation to induce macroscopic behavioral change, we realized rapid spectroscopic screening of genetically encoded effectors or indicators in vivo, and used modulation of ReaChR in the fly as a successful demonstration of such a system. PMID:26601000

  20. Far infrared supplement: Catalog of infrared observations

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1984-01-01

    The Far Infrared Supplement: catalog of infrared observations summarizes all infrared astronomical observations at far infrared wavelengths published in the scientific literature between 1965 and 1982. The Supplement list contains 25% of the observations in the full catalog of infrared observations (C10), and essentially eliminates most visible stars from the listings. The Supplement is more compact than the main Catalog (it does not contain the bibliography and position index of the C10), and is intended for easy reference during astronomical observations.

  1. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  2. Organic Peroxyl Radical Photolysis in the Near-Infrared: Effects on Tropospheric Gregory J. Frost*

    E-print Network

    Ellison, Barney

    of an RO2 to its lowest excited electronic state with near-infrared (near-IR) light is followedOrganic Peroxyl Radical Photolysis in the Near-Infrared: Effects on Tropospheric Chemistry Gregory, Colorado ReceiVed: May 27, 1999; In Final Form: July 30, 1999 We investigate the effects of near-infrared

  3. Fast three-dimensional random access multi-photon microscopy for functional recording of neuronal activity

    NASA Astrophysics Data System (ADS)

    Reddy, Duemani; Saggau, Peter

    2007-07-01

    The dendritic processes of neurons have been shown to possess active and dynamic properties that give them the ability to modulate synaptic integration and shape individual synaptic responses. Effectively studying these properties at multiple locations on a live neuron in highly light scattering brain tissue requires an imaging/recording mechanism with high spatio-temporal resolution as well as optical sectioning and random access site selection capabilities. Our lab has made significant steps in developing such a system by combining the spatial resolution and optical sectioning ability of advanced imaging techniques such as confocal and multi-photon microscopy with the temporal resolution and random access capability provided by acousto-optic laser scanning. However, all systems that have been developed to date restrict fast imaging to two-dimensional (2D) scan patterns. This severely limits the extent to which many neurons can be studied since they represent complex three-dimensional (3D) structures. We have previously demonstrated a scheme for fast 3D scanning which utilizes a unique arrangement of acoustooptic deflectors and does not require axial movements of the objective lens. We have also shown how, when used with the ultra-fast laser pulses needed in multi-photon microscopy, this scheme inherently compensates for the spatial dispersion which would otherwise significantly reduce the resolution of acousto-optic based multi-photon microscopy. We have now coupled this scanning scheme to a modified commercial research microscope and use the combined system to effectively image user-defined sites of interest on fluorescent 3D structures with positioning times that are in the low microsecond (?s) range. The resulting random-access scanning mechanism allows for functional imaging of complex 3D structures such as neuronal dendrites at several thousand volumes per second.

  4. Calculation of the characteristics of radiative multiphoton absorption and emission lines when an atom interacts with pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Glushkov, A. V.; Loboda, A. V.

    2007-03-01

    We have used the quantum electrodynamic theory of moments and the S-matrix formalism of Gell-Mann and Low to carry out numerical modeling of the characteristics (shift, width) of radiative multiphoton absorption lines for an atom in the field of a multimodal laser pulse with gaussian and soliton-like shapes. We have studied the effect of multimode character on the characteristics of multiphoton resonances, using as an example the 6S-6F transition in the cesium atom at the wavelength 1059 nm.

  5. Probing the spatiotemporal relationship between intracellular Ca2+ release and action potential propagation in cardiomyocytes by ultrafast multi-photon random access microscopy

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; Crocini, C.; Coppini, R.; Ferrantini, C.; Tesi, C.; Yan, P.; Loew, L.; Cerbai, E.; Poggesi, C.; Pavone, F. S.

    2013-02-01

    Action potential, via the transverse axial tubular system (TATS), synchronously triggers uniform Ca2+ release throughout the cardiomyocyte. Cardiac diseases associated with TATS structural remodeling preclude a uniform Ca2+ release across the myocyte, contributing to contractile dysfunction. A simultaneous recording of intracellular local Ca2+ release and action potential in tubular network can be useful to unravel the link between TATS abnormality and dysfunctional EC coupling. Here we combine the advantage of an ultrafast random access multi-photon (RAMP) microscope with a double staining approach to optically record AP in several TATS elements and, simultaneously, the corresponding local Ca2+ transient. Isolated rat cardiomyocytes were labeled with a novel voltage sensitive dye (VSD) and a calcium indicator. RAMP microscope rapidly scans between lines drawn across the TATS of the cardiomyocyte to perform a multiplexed measurement of the two fluorescence signals. Although the calcium and voltage indicators can be excited at the same wavelength, the large Stokes shift of the VSD emission allows us to use spectral unmixing to resolve the voltage and calcium responses. In healthy cardiomyocytes, we found uniform AP propagation within the TATS and homogeneous Ca2+ release throughout the whole cell. The capability of our technique in probing spatiotemporal relationship between Ca2+ and electrical activity was then explored in a model of acute detubulation in which failure to conduct AP in disconnected TATS may cause local delay of Ca2+ transient rise leading to non-homogenous Ca2+ release.

  6. Infrared Heaters

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The heating units shown in the accompanying photos are Panelbloc infrared heaters, energy savers which burn little fuel in relation to their effective heat output. Produced by Bettcher Manufacturing Corporation, Cleveland, Ohio, Panelblocs are applicable to industrial or other facilities which have ceilings more than 12 feet high, such as those pictured: at left the Bare Hills Tennis Club, Baltimore, Maryland and at right, CVA Lincoln- Mercury, Gaithersburg, Maryland. The heaters are mounted high above the floor and they radiate infrared energy downward. Panelblocs do not waste energy by warming the surrounding air. Instead, they beam invisible heat rays directly to objects which absorb the radiation- people, floors, machinery and other plant equipment. All these objects in turn re-radiate the energy to the air. A key element in the Panelbloc design is a coating applied to the aluminized steel outer surface of the heater. This coating must be corrosion resistant at high temperatures and it must have high "emissivity"-the ability of a surface to emit radiant energy. The Bettcher company formerly used a porcelain coating, but it caused a production problem. Bettcher did not have the capability to apply the material in its own plant, so the heaters had to be shipped out of state for porcelainizing, which entailed extra cost. Bettcher sought a coating which could meet the specifications yet be applied in its own facilities. The company asked The Knowledge Availability Systems Center, Pittsburgh, Pennsylvania, a NASA Industrial Applications Center (IAC), for a search of NASA's files

  7. In-vivo imaging of psoriatic lesions with polarization multispectral dermoscopy and multiphoton microscopy.

    PubMed

    Kapsokalyvas, Dimitrios; Cicchi, Riccardo; Bruscino, Nicola; Alfieri, Domenico; Prignano, Francesca; Massi, Daniela; Lotti, Torello; Pavone, Francesco S

    2014-07-01

    Psoriasis is a skin autoimmune disease characterized by hyperkeratosis, hyperproliferation of the epidermis and dilatation of dermal papillary blood vessels. Healthy skin (5 volunteers) and psoriatic lesions (3 patients) were visualized in vivo, with high contrast and resolution, with a Polarization Multispectral Dermoscope and a Multiphoton Microscope. Psoriatic features were identified and quantified. The effective diameter of the superficial blood vessels was measured at 35.2 ± 7.2 ?m and the elongated dermal papillae had an effective diameter of 64.2 ± 22.6 ?m. The methodologies developed could be employed for quantitative diagnostic purposes and furthermore serve as a monitoring method of the effect of personalized treatments. PMID:25071974

  8. Experimental Quantum Teleportation and Multi-Photon Entanglement via Interfering Narrowband Photon Sources

    E-print Network

    Jian Yang; Xiao-Hui Bao; Han Zhang; Shuai Chen; Cheng-Zhi Peng; Zeng-Bing Chen; Jian-Wei Pan

    2009-09-06

    In this letter, we report a realization of synchronization-free quantum teleportation and narrowband three-photon entanglement through interfering narrowband photon sources. Since both the single-photon and the entangled photon pair utilized are completely autonomous, it removes the requirement of high demanding synchronization technique in long-distance quantum communication with pulsed spontaneous parametric down-conversion sources. The frequency linewidth of the three-photon entanglement realized is on the order of several MHz, which matches the requirement of atomic ensemble based quantum memories. Such a narrowband multi-photon source will have applications in some advanced quantum communication protocols and linear optical quantum computation.

  9. Histology in vivo: chemical contrast combined with clinical multimodal multiphoton tomography

    NASA Astrophysics Data System (ADS)

    Weinigel, Martin; Breunig, Hans Georg; Koenig, Karsten

    2015-03-01

    Label-free multiphoton tomography based on two-photon autofluorescence, fluorescence lifetime, and second harmonic generation imaging can be supplemented by coherent anti-Stokes Raman scattering. We present a compact, mobile and flexible clinical tomograph equipped with a novel detector design with multiple miniaturized detectors for individual acquisition of all four contrast mechanisms. Imaging of endogenous fluorophores, SHG-active collagen as well as nonfluorescent lipids in human skin in vivo is possible with this clinical tomograph paving the way towards in vivo histology.

  10. Characterization of corneal damage from Pseudomonas aeruginosa infection by the use of multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Lin; Chen, Wei-Liang; Lo, Wen; Chen, Shean-Jen; Tan, Hsin-Yuan; Dong, Chen-Yuan

    2010-11-01

    Using multiphoton autofluorescence (MAF) and second harmonic generation (SHG) microscopy, we investigate the morphology and the structure of the corneal epithelium and stroma collagen of bovine cornea following injection of Pseudomonas aeruginosa. We found that corneal epithelial cells are damaged and stromal collagen becoming increasingly autofluorescent with time. We also characterized infected cornea cultured for 0, 6, 12, and 24 h by quantitative ratiometric MAF to SHG index (MAFSI) analysis. MAFSI results show that the destruction of the stromal collagen corresponds to a decrease in SHG intensity and increase of MAF signal with time.

  11. Direct detection of atomic ions from molecular photofragmentation during nonresonant multiphoton ionization of sputtered species

    SciTech Connect

    Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Burnett, J.W.; White, J.M.

    1993-09-01

    The photoionization of sputtered Cu, Al, and Ru atoms and dimers was investigated by measuring velocity distributions using both resonant and nonresonant photoionization. Nonresonant ionization produced an atomic distribution that peaked at the same velocity as the respective dimer distribution, indicating that virtually all the nonresonant atomic ion signal is from photofragmented dimers. Various mechanisms of dimer photofragmentation are discussed. Domination of the atomic photoion channel by molecule fragmentation appears to be a general phenomenon that must be accounted for in all gas-phase multiphoton nonresonant ionization experiments at easily achievable laser power densities ({le} 10{sup 9} W/cm{sup 2}).

  12. Multiphoton resonances for all-optical quantum logic with multiple cavities

    NASA Astrophysics Data System (ADS)

    Everitt, Mark S.; Garraway, Barry M.

    2014-07-01

    We develop a theory for the interaction of multilevel atoms with multimode cavities yielding cavity-enhanced multiphoton resonances. The locations of the resonances are predicted from the use of effective two- and three-level Hamiltonians. As an application we show that quantum gates can be realized when photonic qubits are encoded on the cavity modes in arrangements where ancilla atoms transit the cavity. The fidelity of operations is increased by conditional measurements on the atom and by the use of a selected, dual-rail, Hilbert space. A universal set of gates is proposed, including the Fredkin gate and iswap operation; the system seems promising for scalability.

  13. Coherent control of radiation patterns of nonlinear multiphoton processes in nanoparticles

    PubMed Central

    Papoff, Francesco; McArthur, Duncan; Hourahine, Ben

    2015-01-01

    We propose a scheme for the coherent control of light waves and currents in metallic nanospheres which applies independently of the nonlinear multiphoton processes at the origin of waves and currents. We derive conditions on the external control field which enable us to change the radiation pattern and suppress radiative losses or to reduce absorption, enabling the particle to behave as a perfect scatterer or as a perfect absorber. The control introduces narrow features in the response of the particles that result in high sensitivity to small variations in the local environment, including subwavelength spatial shifts. PMID:26155833

  14. Electroluminescence and multiphoton effects in a resonator driven by a tunnel junction

    NASA Astrophysics Data System (ADS)

    Jin, Jinshuang; Marthaler, Michael; Schön, Gerd

    2015-02-01

    We study a transmission line resonator which is driven by electrons tunneling through a voltage-biased tunnel junction. Using the Born-Markovian quantum master equation in the polaron basis we investigate the nonequilibrium photon state and emission spectrum of the resonator as well as properties of the transport current across the tunnel junction and its noise spectrum. The electroluminescence is optimized, with maximum peak height and narrow linewidth, when the back-action of the tunnel junction on the resonator and the damping of the resonator are similar in strength. For strong coupling between the resonator and tunnel junction, multiphoton effects create signatures in the transport current and current noise spectrum.

  15. In-vivo imaging of psoriatic lesions with polarization multispectral dermoscopy and multiphoton microscopy

    PubMed Central

    Kapsokalyvas, Dimitrios; Cicchi, Riccardo; Bruscino, Nicola; Alfieri, Domenico; Prignano, Francesca; Massi, Daniela; Lotti, Torello; Pavone, Francesco S.

    2014-01-01

    Psoriasis is a skin autoimmune disease characterized by hyperkeratosis, hyperproliferation of the epidermis and dilatation of dermal papillary blood vessels. Healthy skin (5 volunteers) and psoriatic lesions (3 patients) were visualized in vivo, with high contrast and resolution, with a Polarization Multispectral Dermoscope and a Multiphoton Microscope. Psoriatic features were identified and quantified. The effective diameter of the superficial blood vessels was measured at 35.2 ± 7.2 ?m and the elongated dermal papillae had an effective diameter of 64.2 ± 22.6 ?m. The methodologies developed could be employed for quantitative diagnostic purposes and furthermore serve as a monitoring method of the effect of personalized treatments. PMID:25071974

  16. Single- and multi-photon ionization studies of organosulfur species

    SciTech Connect

    Cheung, Y.S.

    1999-02-12

    Accurate ionization energies (IE`s) for molecular species are used for prediction of chemical reactivity and are of fundamental importance to chemists. The IE of a gaseous molecule can be determined routinely in a photoionization or a photoelectron experiment. IE determinations made in conventional photoionization and photoelectron studies have uncertainties in the range of 3--100 meV (25--250 cm{sup {minus}1}). In the past decade, the most exciting development in the field of photoionization and photoelectron spectroscopy has been the availability of high resolution, tunable ultraviolet (UV) and vacuum ultraviolet (VUV) laser sources. The laser pulsed field ionization photoelectron (PFI-PE) scheme is currently the state-of-the-art photoelectron spectroscopic technique and is capable of providing photoelectron energy resolution close to the optical resolution. The author has focused attention on the photoionization processes of some sulfur-containing species. The studies of the photoionization and photodissociation on sulfur-containing compounds [such as CS{sub 2}, CH{sub 3}SH, CH{sub 3}SSCH{sub 3}, CH{sub 3}CH{sub 2}SCH{sub 2}CH{sub 3}, HSCH{sub 2}CH{sub 2}SH and C{sub 4}H{sub 4}S (thiophene) and sulfur-containing radicals, such as HS, CS, CH{sub 3}S, CH{sub 3}CH{sub 2}S and CH{sub 3}SS], have been the major subjects in the group because sulfur is an important species contributing to air pollution in the atmosphere. The modeling of the combustion and oxidation of sulfur compounds represents important steps for the control of both the production and the elimination of sulfur-containing pollutants. Chapter 1 is a general introduction of the thesis. Chapters 2 and 6 contain five papers published in, or accepted for publication in, academic periodicals. In Chapter 7, the progress of the construction in the laboratory of a new vacuum ultraviolet laser system equipped with a reflectron mass spectrometer is presented. Chapters 2 through 7 have been removed for separate processing. A general conclusion of these studies are given in Chapter 8 followed by an appendix.

  17. Far infrared supplement: Catalog of infrared observations

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1982-01-01

    The development of a new generation of orbital, airborne and ground-based infrared astronomical observatory facilities, including the infrared astronomical satellite (IRAS), the cosmic background explorer (COBE), the NASA Kuiper airborne observatory, and the NASA infrared telescope facility, intensified the need for a comprehensive, machine-readable data base and catalog of current infrared astronomical observations. The Infrared Astronomical Data Base and its principal data product, this catalog, comprise a machine-readable library of infrared (1 micrometer to 1000 micrometers) astronomical observations published in the scientific literature since 1965.

  18. Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wehling, Randy L.

    Infrared (IR) spectroscopy refers to measurement of the absorption of different frequencies of IR radiation by foods or other solids, liquids, or gases. IR spectroscopy began in 1800 with an experiment by Herschel. When he used a prism to create a spectrum from white light and placed a thermometer at a point just beyond the red region of the spectrum, he noted an increase in temperature. This was the first observation of the effects of IR radiation. By the 1940s, IR spectroscopy had become an important tool used by chemists to identify functional groups in organic compounds. In the 1970s, commercial near-IR reflectance instruments were introduced that provided rapid quantitative determinations of moisture, protein, and fat in cereal grains and other foods. Today, IR spectroscopy is used widely in the food industry for both qualitative and quantitative analysis of ingredients and finished foods.

  19. Infrared technology 26

    SciTech Connect

    Spiro, I.J. )

    1990-01-01

    This conference is organized under the following sessions: Military and scientific applications; Thermal imaging and simulation; Infrared in France I: Atmospherics and astrophysics; Infrared in France II: Spectroscopy and applications; Infrared in France III: Thermography and scientific applications; Scientific applications.

  20. Spectroscopic investigations of the vibrational potential energy surfaces in electronic ground and excited states 

    E-print Network

    Yang, Juan

    2007-09-17

    The vibrational potential energy surfaces in electronic ground and excited states of several ring molecules were investigated using several different spectroscopic methods, including far-infrared (IR), Raman, ultraviolet ...

  1. Thermal Infrared Remote Sensing

    E-print Network

    Imagery of NewImagery of New York CityYork City Thermal InfraredThermal InfraredAerial PhotographThermal Infrared Remote Sensing #12;0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 violet limit blue green limit near-infrared far infrared ultraviolet Thermal Infrared refers to region o EM spectrum from ~3 - 14 µm

  2. A high speed multifocal multiphoton fluorescence lifetime imaging microscope for live-cell FRET imaging

    PubMed Central

    Poland, Simon P.; Krstaji?, Nikola; Monypenny, James; Coelho, Simao; Tyndall, David; Walker, Richard J.; Devauges, Viviane; Richardson, Justin; Dutton, Neale; Barber, Paul; Li, David Day-Uei; Suhling, Klaus; Ng, Tony; Henderson, Robert K.; Ameer-Beg, Simon M.

    2015-01-01

    We demonstrate diffraction limited multiphoton imaging in a massively parallel, fully addressable time-resolved multi-beam multiphoton microscope capable of producing fluorescence lifetime images with sub-50ps temporal resolution. This imaging platform offers a significant improvement in acquisition speed over single-beam laser scanning FLIM by a factor of 64 without compromising in either the temporal or spatial resolutions of the system. We demonstrate FLIM acquisition at 500 ms with live cells expressing green fluorescent protein. The applicability of the technique to imaging protein-protein interactions in live cells is exemplified by observation of time-dependent FRET between the epidermal growth factor receptor (EGFR) and the adapter protein Grb2 following stimulation with the receptor ligand. Furthermore, ligand-dependent association of HER2-HER3 receptor tyrosine kinases was observed on a similar timescale and involved the internalisation and accumulation or receptor heterodimers within endosomes. These data demonstrate the broad applicability of this novel FLIM technique to the spatio-temporal dynamics of protein-protein interaction. PMID:25780724

  3. Characterizing liver capsule microstructure via in situ bulge test coupled with multiphoton imaging.

    PubMed

    Jayyosi, C; Coret, M; Bruyère-Garnier, K

    2016-02-01

    The characterization of biological tissue at the microscopic scale is the starting point of many applications in tissue engineering and especially in the development of structurally based constitutive models. In the present study, focus is made on the liver capsule, the membrane encompassing hepatic parenchyma, which takes a huge part in liver mechanical properties. An in situ bulge test experiment under a multiphoton microscope has been developed to assess the microstructure changes that arise with biaxial loading. Multiphoton microscopy allows to observe the elastin and collagen fiber networks simultaneously. Thus a description of the microstructure organization of the capsule is given, characterizing the shapes, geometry and arrangement of fibers. The orientation of fibers is calculated and orientation distribution evolution with loading is given, in the case of an equibiaxial and two non equibiaxial loadings, thanks to a circular and elliptic set up of the bulge test. The local strain fields have also been computed, by the mean of a photobleaching grid, to get an idea of what the liver capsule might experience when subjected to internal pressure. Results show that strain fields present some heterogeneity due to anisotropy. Reorientation occurs in non equibiaxial loadings and involves fibers layers from the inner to the outer surface as expected. Although there is a fiber network rearrangement to accommodate with loading in the case of equibiaxial loading, there is no significant reorientation of the main fibers direction of the different layers. PMID:26476966

  4. Multiphoton Ionization of Atoms and Molecules with Soft and Hard X-rays

    NASA Astrophysics Data System (ADS)

    Rolles, Daniel

    2015-05-01

    We have recently extended our previous investigations of the multiphoton ionization of heavy atoms, such as Kr and Xe, and of high-Z atom containing molecules from the soft into the hard X-ray range as well as into the XUV regime. Using the 100-nm focus environment at LCLS, we were able to reach peak intensities up to 1019W/cm2 at photon energies between 5 to 9 keV. This allows studying atomic and molecular ionization processes under unprecedented X-ray intensities and, in particular, under the identical conditions where typical coherent diffractive imaging experiments are performed. Our results are thus important benchmarks for calculating radiation damage effects in FEL-based X-ray imaging experiments. Using new micro-focusing capabilities at FLASH, we also extended our studies into the XUV range between 70 and 200 eV photon energy and observed significantly higher charge states than previously reported. I will present the results from our recent measurements at LCLS and FLASH and discuss the different multiphoton ionization mechanisms that play a role in the XUV, soft, and hard X-ray range.

  5. A high speed multifocal multiphoton fluorescence lifetime imaging microscope for live-cell FRET imaging.

    PubMed

    Poland, Simon P; Krstaji?, Nikola; Monypenny, James; Coelho, Simao; Tyndall, David; Walker, Richard J; Devauges, Viviane; Richardson, Justin; Dutton, Neale; Barber, Paul; Li, David Day-Uei; Suhling, Klaus; Ng, Tony; Henderson, Robert K; Ameer-Beg, Simon M

    2015-02-01

    We demonstrate diffraction limited multiphoton imaging in a massively parallel, fully addressable time-resolved multi-beam multiphoton microscope capable of producing fluorescence lifetime images with sub-50ps temporal resolution. This imaging platform offers a significant improvement in acquisition speed over single-beam laser scanning FLIM by a factor of 64 without compromising in either the temporal or spatial resolutions of the system. We demonstrate FLIM acquisition at 500 ms with live cells expressing green fluorescent protein. The applicability of the technique to imaging protein-protein interactions in live cells is exemplified by observation of time-dependent FRET between the epidermal growth factor receptor (EGFR) and the adapter protein Grb2 following stimulation with the receptor ligand. Furthermore, ligand-dependent association of HER2-HER3 receptor tyrosine kinases was observed on a similar timescale and involved the internalisation and accumulation or receptor heterodimers within endosomes. These data demonstrate the broad applicability of this novel FLIM technique to the spatio-temporal dynamics of protein-protein interaction. PMID:25780724

  6. Hybrid multiphoton volumetric functional imaging of large-scale bioengineered neuronal networks

    NASA Astrophysics Data System (ADS)

    Dana, Hod; Marom, Anat; Paluch, Shir; Dvorkin, Roman; Brosh, Inbar; Shoham, Shy

    2014-06-01

    Planar neural networks and interfaces serve as versatile in vitro models of central nervous system physiology, but adaptations of related methods to three dimensions (3D) have met with limited success. Here, we demonstrate for the first time volumetric functional imaging in a bioengineered neural tissue growing in a transparent hydrogel with cortical cellular and synaptic densities, by introducing complementary new developments in nonlinear microscopy and neural tissue engineering. Our system uses a novel hybrid multiphoton microscope design combining a 3D scanning-line temporal-focusing subsystem and a conventional laser-scanning multiphoton microscope to provide functional and structural volumetric imaging capabilities: dense microscopic 3D sampling at tens of volumes per second of structures with mm-scale dimensions containing a network of over 1,000 developing cells with complex spontaneous activity patterns. These developments open new opportunities for large-scale neuronal interfacing and for applications of 3D engineered networks ranging from basic neuroscience to the screening of neuroactive substances.

  7. In vivo imaging of spinal cord in contusion injury model mice by multi-photon microscopy

    NASA Astrophysics Data System (ADS)

    Oshima, Y.; Horiuchi, H.; Ogata, T.; Hikita, A.; Miura, H.; Imamura, T.

    2014-03-01

    Fluorescent imaging technique is a promising method and has been developed for in vivo applications in cellular biology. In particular, nonlinear optical imaging technique, multi-photon microscopy has make it possible to analyze deep portion of tissues in living animals such as axons of spinal code. Traumatic spinal cord injuries (SCIs) are usually caused by contusion damages. Therefore, observation of spinal cord tissue after the contusion injury is necessary for understanding cellular dynamics in response to traumatic SCI and development of the treatment for traumatic SCI. Our goal is elucidation of mechanism for degeneration of axons after contusion injuries by establishing SCI model and chronic observation of injured axons in the living animals. Firstly we generated and observed acute SCI model by contusion injury. By using a multi-photon microscope, axons in dorsal cord were visualized approximately 140 micron in depth from the surface. Immediately after injury, minimal morphological change of spinal cord was observed. At 3 days after injury, spinal cord was swelling and the axons seem to be fragmented. At 7 days after injury, increased degradation of axons could be observed, although the image was blurred due to accumulation of the connective tissue. In the present study, we successfully observed axon degeneration after the contusion SCI in a living animal in vivo. Our final goal is to understand molecular mechanisms and cellular dynamics in response to traumatic SCIs in acute and chronic stage.

  8. Multiphoton crosslinking for biocompatible 3D printing of type I collagen.

    PubMed

    Bell, Alex; Kofron, Matthew; Nistor, Vasile

    2015-01-01

    Multiphoton fabrication is a powerful technique for three-dimensional (3D) printing of structures at the microscale. Many polymers and proteins have been successfully structured and patterned using this method. Type I collagen comprises a large part of the extracellular matrix for most tissue types and is a widely used cellular scaffold material for tissue engineering. Current methods for creating collagen tissue scaffolds do not allow control of local geometry on a cellular scale. This means the environment experienced by cells may be made up of the native material but unrelated to native cellular-scale structure. In this study, we present a novel method to allow multiphoton crosslinking of type I collagen with flavin mononucleotide photosensitizer. The method detailed allows full 3D printing of crosslinked structures made from unmodified type I collagen and uses only demonstrated biocompatible materials. Resolution of 1 ?m for both standing lines and high-aspect ratio gaps between structures is demonstrated and complex 3D structures are fabricated. This study demonstrates a means for 3D printing with one of the most widely used tissue scaffold materials. High-resolution, 3D control of the fabrication of collagen scaffolds will facilitate higher fidelity recreation of the native extracellular environment for engineered tissues. PMID:26335389

  9. Multiphoton microscopy as a diagnostic tool for pathological analysis of sentinel lymph nodes

    NASA Astrophysics Data System (ADS)

    Lemiere, J.; Douady, J.; Estève, F.; Salameire, D.; Lantuejoul, S.; Lorimier, P.; Ricard, C.; van der Sanden, B.; Vial, J.-C.

    2009-02-01

    Multiphoton microscopy has shown a powerful potential for biomedical in vivo and ex vivo analysis of tissue sections and explants. Studies were carried out on several animal organs such as brain, arteries, lungs, and kidneys. One of the current challenges is to transfer to the clinic the knowledge and the methods previously developed in the labs at the preclinical level. For tumour staging, physicians often remove the lymph nodes that are localized at the proximity of the lesion. In case of breast cancer or melanoma, sentinel lymph node protocol is performed: pathologists randomly realize an extensive sampling of formol fixed nodes. However, the duration of this protocol is important and its reliability is not always satisfactory. The aim of our study was to determine if multiphoton microscopy would enable the fast imaging of lymph nodes on important depths, with or without exogenous staining. Experiments were first conducted on pig lymph nodes in order to test various dyes and to determine an appropriate protocol. The same experiments were then performed on thin slices of human lymph nodes bearing metastatic melanoma cells. We obtained relevant images with both endofluorescence plus second-harmonic generation and xanthene dyes. They show a good contrast between tumour and healthy cells. Furthermore, images of pig lymph nodes were recorded up to 120?m below the surface. This new method could then enable a faster diagnosis with higher efficiency for the patient. Experiments on thicker human lymph nodes are currently underway in order to validate these preliminary results.

  10. Second harmonic generation in surface periodically-poled lithium niobate waveguides: on the role of multiphoton absorption

    E-print Network

    Cherchi, M; Pasquazi, A; Busacca, A C; Sanseverino, S Riva; Cino, A C; Colace, L; Assanto, G; 10.1007/s00340-008-3219-8

    2009-01-01

    Second harmonic generation is investigated in lithium niobate channels realized by proton exchange and quasi-phase-matched by surface periodic-poling. The reduction in conversion efficiency at high powers is interpreted in terms of multi-photon absorption via two-color terms, yielding an estimate of the dominating three-photon process.

  11. Continuous-wave cascaded-harmonic generation and multi-photon Raman lasing in lithium niobate whispering-gallery resonators

    E-print Network

    Carmon, Tal

    Continuous-wave cascaded-harmonic generation and multi-photon Raman lasing in lithium niobate lasing in lithium niobate whispering-gallery resonators Jeremy Moore, Matthew Tomes, Tal Carmon, and Mona lasing in a millimeter-scale lithium niobate whispering-gallery resonator pumped at a telecommunication

  12. Verification Results of Jet Resonance-enhanced Multiphoton Ionization as a Real-time PCDD/F Emission Monitor

    EPA Science Inventory

    The Jet REMPI (Resonance Enhanced Multiphoton Ionization) monitor was tested on a hazardous waste firing boiler for its ability to determine concentrations of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/Fs). Jet REMPI is a real time instrument capable of highly selec...

  13. Statistical analysis on activation and photo-bleaching of step-wise multi-photon activation fluorescence of melanin

    NASA Astrophysics Data System (ADS)

    Gu, Zetong; Lai, Zhenhua; Zhang, Xi; Yin, Jihao; DiMarzio, Charles A.

    2015-03-01

    Melanin is regarded as the most enigmatic pigments/biopolymers found in most organisms. We have shown previously that melanin goes through a step-wise multi-photon absorption process after the fluorescence has been activated with high laser intensity. No melanin step-wise multi-photon activation fluorescence (SMPAF) can be obtained without the activation process. The step-wise multi-photon activation fluorescence has been observed to require less laser power than what would be expected from a non-linear optical process. In this paper, we examined the power dependence of the activation process of melanin SMPAF at 830nm and 920nm wavelengths. We have conducted research using varying the laser power to activate the melanin in a point-scanning mode for multi-photon microscopy. We recorded the fluorescence signals and position. A sequence of experiments indicates the relationship of activation to power, energy and time so that we can optimize the power level. Also we explored regional analysis of melanin to study the spatial relationship in SMPAF and define three types of regions which exhibit differences in the activation process.

  14. Preclinical study of using multiphoton microscopy to diagnose liver cancer and differentiate benign and malignant liver lesions

    NASA Astrophysics Data System (ADS)

    Yan, Jun; Zhuo, Shuangmu; Chen, Gang; Wu, Xiufeng; Zhou, Dong; Xie, Shusen; Jiang, Jiahao; Ying, Mingang; Jia, Fan; Chen, Jianxin; Zhou, Jian

    2012-02-01

    Recently, the miniaturized multiphoton microscopy (MPM) and multiphoton probe allow the clinical use of multiphoton endoscopy for diagnosing cancer via ``optical biopsy''. The purpose of this study was to establish MPM optical diagnostic features for liver cancer and evaluate the sensitivity, specificity, and accuracy of MPM optical diagnosis. Firstly, we performed a pilot study to establish the MPM diagnostic features by investigating 60 surgical specimens, and found that high-resolution MPM images clearly demonstrated apparent differences between benign and malignant liver lesions in terms of their tissue architecture and cell morphology. Cancer cells, characterized by irregular size and shape, enlarged nuclei, and increased nuclear-cytoplasmic ratio, were identified by MPM images, which were comparable to hematoxylin-eosin staining images. Secondly, we performed a blinded study to evaluate the sensitivity, specificity, and accuracy of MPM optical diagnosis by investigating another 164 specimens, and found that the sensitivity, specificity, and accuracy of MPM diagnosis was 96.32%, 96.43%, and 96.34%, respectively. In conclusion, it is feasible to use MPM to diagnose liver cancer and differentiate benign and malignant liver lesions. This preclinical study provides the groundwork for further using multiphoton endoscopy to perform real-time noninvasive ``optical biopsy'' for liver lesions in the near future.

  15. USE OF MULTIPHOTON LASER SCANNING MICROSCOPY TO IMAGE BENZO[A]PYRENE AND METABOLITES IN FISH EARLY LIFE STAGES

    EPA Science Inventory

    Multiphoton laser scanning micrsocopy holds promise as a tool to study the tissue distribution of environmental chemical contaminants during fish early life stage development. One such chemical for which this is possible is benzo[a]pyrene (BaP), a polyaromatic hydrocarbon that a...

  16. USE OF MULTIPHOTON LASER SCANNING MICROSCOPY TO IMAGE BENZO[A]PYRENE AND METABOLITES IN FISH EGGS

    EPA Science Inventory

    Multiphoton laser scanning microscopy (MPLSM) is a promising tool to study the tissue distribution of environmental chemical contaminants during fish early life stages. One such chemical for which this is possible is benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon that a...

  17. Multiphoton microscopy can visualize zonal damage and decreased cellular metabolic activity in hepatic ischemia-reperfusion injury in rats

    NASA Astrophysics Data System (ADS)

    Thorling, Camilla A.; Liu, Xin; Burczynski, Frank J.; Fletcher, Linda M.; Gobe, Glenda C.; Roberts, Michael S.

    2011-11-01

    Ischemia-reperfusion (I/R) injury is a common occurrence in liver surgery. In orthotopic transplantation, the donor liver is exposed to periods of ischemia and when oxygenated blood is reintroduced to the liver, oxidative stress may develop and lead to graft failure. The aim of this project was to investigate whether noninvasive multiphoton and fluorescence lifetime imaging microscopy, without external markers, were useful in detecting early liver damage caused by I/R injury. Localized hepatic ischemia was induced in rats for 1 h followed by 4 h reperfusion. Multiphoton and fluorescence lifetime imaging microscopy was conducted prior to ischemia and up to 4 h of reperfusion and compared to morphological and biochemical assessment of liver damage. Liver function was significantly impaired at 2 and 4 h of reperfusion. Multiphoton microscopy detected liver damage at 1 h of reperfusion, manifested by vacuolated cells and heterogeneous spread of damage over the liver. The damage was mainly localized in the midzonal region of the liver acinus. In addition, fluorescence lifetime imaging showed a decrease in cellular metabolic activity. Multiphoton and fluorescence lifetime imaging microscopy detected evidence of early I/R injury both structurally and functionally. This provides a simple noninvasive technique useful for following progressive liver injury without external markers.

  18. Observation of interference effects via four photon excitation of highly excited Rydberg states in thermal cesium vapor

    E-print Network

    Kondo, Jorge M; Guttridge, Alex; Wade, Christopher G; De Melo, Natalia R; Adams, Charles S; Weatherill, Kevin J

    2015-01-01

    We report on the observation of Electromagnetically Induced Transparency (EIT) and Absorption (EIA) of highly-excited Rydberg states in thermal Cs vapor using a 4-step excitation scheme. The advantage of this 4-step scheme is that the final transition to the Rydberg state has a large dipole moment and one can achieve similar Rabi frequencies to 2 or 3 step excitation schemes using two orders of magnitude less laser power. Consequently each step is driven by a relatively low power infra-red diode laser opening up the prospect for new applications. The observed lineshapes are in good agreement with simulations based on multilevel optical Bloch equations.

  19. 8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  20. Enhanced melanin fluorescence by stepwise three-photon excitation.

    PubMed

    Kerimo, Josef; Rajadhyaksha, Milind; DiMarzio, Charles A

    2011-01-01

    The fluorescence of eumelanin (from Sepia officinalis and black human hair) was activated and enhanced by almost three orders of magnitude by exposure to near-infrared radiation. No activation or enhanced emission was observed when the samples were heated up to 100°C. The near-infrared irradiation caused obvious changes to the eumelanin and could be seen by fluorescence and bright field imaging. The area of enhanced emission appeared to originate from a region with changes in the morphology of the eumelanin's granule and increased with exposure time. At least two different components with enhanced fluorescence were activated and could be distinguished by their excitation properties. One component could be excited efficiently with wavelengths in the visible region and exhibited linear absorption dependence with respect to the laser power level. The second component could be excited efficiently using near-infrared wavelengths by a nonlinear process and exhibited a third-order dependence on the excitation. The third-order dependence is explained by a step-wise excited-state absorption process since the same third-order dependence was present when either continuous wave or femtosecond pulsed laser, with similar average-power levels, was used. PMID:21668873