Sample records for infrared multiphoton excitation

  1. Photophysics of infrared multiphoton excitation in thiophosgene

    SciTech Connect

    Brenner, D.M.; Spencer, M.N.; Steinfeld, J.I.

    1983-01-01

    IR multiphoton absorption (IRMPA) in thiophosgene has been studied by IR-visible double resonance. In particular, the probability of absorption has been measured in both collision-free (molecular beam) and collision-perturbed environments by monitoring the depopulation of the ground state level (000000). Although no evidence for true multiphoton absorption is found, a number of important observations have been made. (1) No correlation exists between the IRMPA spectrum under collision-free conditions and the low energy IR absorption spectrum. (2) Homogeneous depletion of rotational populations occurs at all CO/sub 2/-laser frequencies. (3) Bottlenecks to absorption do not occur in the pumped-mode ladder. (4) The probability of absorption depends inversely on pressure and is affected dramatically by long-range collisions. These results are interpreted in the framework of an optical Bloch equation model.

  2. All-near-infrared multiphoton microscopy interrogates intact tissues at deeper imaging depths than conventional single- and two-photon near-infrared excitation microscopes

    PubMed Central

    Sarder, Pinaki; Yazdanfar, Siavash; Akers, Walter J.; Tang, Rui; Sudlow, Gail P.; Egbulefu, Christopher; Achilefu, Samuel

    2013-01-01

    Abstract. The era of molecular medicine has ushered in the development of microscopic methods that can report molecular processes in thick tissues with high spatial resolution. A commonality in deep-tissue microscopy is the use of near-infrared (NIR) lasers with single- or multiphoton excitations. However, the relationship between different NIR excitation microscopic techniques and the imaging depths in tissue has not been established. We compared such depth limits for three NIR excitation techniques: NIR single-photon confocal microscopy (NIR SPCM), NIR multiphoton excitation with visible detection (NIR/VIS MPM), and all-NIR multiphoton excitation with NIR detection (NIR/NIR MPM). Homologous cyanine dyes provided the fluorescence. Intact kidneys were harvested after administration of kidney-clearing cyanine dyes in mice. NIR SPCM and NIR/VIS MPM achieved similar maximum imaging depth of ?100???m. The NIR/NIR MPM enabled greater than fivefold imaging depth (>500???m) using the harvested kidneys. Although the NIR/NIR MPM used 1550-nm excitation where water absorption is relatively high, cell viability and histology studies demonstrate that the laser did not induce photothermal damage at the low laser powers used for the kidney imaging. This study provides guidance on the imaging depth capabilities of NIR excitation-based microscopic techniques and reveals the potential to multiplex information using these platforms. PMID:24150231

  3. Multi-photon excitation microscopy

    Microsoft Academic Search

    Alberto Diaspro; Paolo Bianchini; Giuseppe Vicidomini; Mario Faretta; Paola Ramoino; Cesare Usai

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase

  4. Multi-photon excitation microscopy.

    PubMed

    Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

  5. Multi-photon excitation microscopy

    PubMed Central

    Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

  6. vuv fluorescence from selective high-order multiphoton excitation of Nâ

    Microsoft Academic Search

    George N. Gibson

    2004-01-01

    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 Nâ and Ar with high-intensity infrared ultrashort laser pulses. Both Nâ

  7. Photoionization of excited molecular states using multiphoton excitation techniques

    NASA Astrophysics Data System (ADS)

    Dehmer, P. M.; Pratt, S. T.; Dehmer, J. L.

    Resonantly enhanced multiphoton ionization (REMPI) affords the opportunity to select a specific ionization pathway in order to produce a particular ionic state for further study or to investigate detailed aspects of excited state photoionization dynamics. The production of electronic or vibrational state-selected ions using REMPI is achieved by first preparing an intermediate Rydberg state that has a potential energy curve similar to that of the final desired ionic state, and then ionizing the Rydberg state with a single additional photon. Under these circumstances, the Franck-Condon factors governing the final ionization step strongly favor the preservation of the Rydberg state core.

  8. Photoionization of excited molecular states using multiphoton excitation techniques

    NASA Astrophysics Data System (ADS)

    Dehmer, P. M.; Pratt, S. T.; Dehmer, J. L.

    1984-09-01

    Photoelectron spectra are reported for three photon resonant, four photon ionization of H2 via the B 1?+u, v=7 (J=2,4) and C 1?u, v=0-4 (J=1) levels and of N2 via the o3 1?u, v=1,2, b 1?u, v=3-5, and c 1?u, v=0 levels. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon factors are observed, which reflect the more subtle dynamics of excited state photoionization.

  9. vuv fluorescence from selective high-order multiphoton excitation of N2

    Microsoft Academic Search

    George N. Gibson

    2004-01-01

    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 N2 and Ar with high-intensity infrared ultrashort laser pulses. Both N2

  10. Two-color multiphoton resonant excitation of three-level atoms

    SciTech Connect

    Avetissian, H. K.; Avchyan, B. R.; Mkrtchian, G. F. [Department of Quantum Electronics, Yerevan State University, 1 A. Manukian, Yerevan 375025 (Armenia)

    2006-12-15

    The multiphoton resonant excitation of three-level atoms by the two laser fields of different frequencies is investigated. The time evolution of the system and analytical solutions expressing Rabi oscillations of the probability amplitudes at the two-color multiphoton resonant excitation are found using a nonperturbative resonant approach. The specific examples for experimental implementation of two-color multiphoton resonant excitation of hydrogen atoms are considered.

  11. Multi-photon excited luminescence of magnetic FePt core-shell nanoparticles

    PubMed Central

    Seemann, K.M.; Kuhn, B.

    2014-01-01

    We present magnetic FePt nanoparticles with a hydrophilic, inert, and biocompatible silico-tungsten oxide shell. The particles can be functionalized, optically detected, and optically manipulated. To show the functionalization the fluorescent dye NOPS was bound to the FePt core-shell nanoparticles with propyl-triethoxy-silane linkers and fluorescence of the labeled particles were observed in ethanol (EtOH). In aqueous dispersion the NOPS fluorescence is quenched making them invisible using 1-photon excitation. However, we observe bright luminescence of labeled and even unlabeled magnetic core-shell nanoparticles with multi-photon excitation. Luminescence can be detected in the near ultraviolet and the full visible spectral range by near infrared multi-photon excitation. For optical manipulation, we were able to drag clusters of particles, and maybe also single particles, by a focused laser beam that acts as optical tweezers by inducing an electric dipole in the insulated metal nanoparticles. In a first application, we show that the luminescence of the core-shell nanoparticles is bright enough for in vivo multi-photon imaging in the mouse neocortex down to cortical layer 5. PMID:25071977

  12. Control of multiphoton molecular excitation with shaped femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Xu, Bingwei

    The work presented in this dissertation describes the use of shaped femtosecond laser pulses to control the outcome of nonlinear optical process and thus to achieve the selectivity for multiphoton molecular transitions. This research could lead to applications in various fields including nonlinear optical spectroscopy, chemical identification, biological imaging, communications, photodynamic therapy, etc. In order to realize accurate pulse shaping of the femtosecond laser pulses, it is essential to measure and correct the spectral phase distortion of such pulses. A method called multiphoton intrapulse interference phase scan is used to do so throughout this dissertation. This method is highly accurate and reproducible, and has been proved in this work to be compatible with any femtosecond pulses regardless of bandwidth, intensity and repetition rate of the laser. The phase control of several quasi-octave laser sources is demonstrated in this dissertation, with the generation of 4.3 fs and 5.9 fs pulses that reach the theoretically predicted transform-limited pulse duration. The excellent phase control achieved also guarantees the reproducibility for selective multiphoton excitations by accurate phase and/or amplitude shaping. Selective two-photon excitation, stimulated Raman scattering and coherent anti-Stokes Raman scattering with a single broadband laser source are demonstrated in this dissertation. Pulse shaping is used to achieve a fast and robust approach to measure the two-photon excitation spectrum from fluorescent molecules, which provide important information for two-photon biological imaging. The selective excitation concept is also applied in the field of remote chemical identification. Detection of characteristic Raman lines for several chemicals using a single beam coherent anti-Stokes Raman scattering spectroscopy from a 12 meter standoff distance is shown, providing a promising approach to standoff detection of chemicals, hazardous contaminations, and explosives.

  13. Controlled damage in thick specimens by multiphoton excitation.

    PubMed

    Galbraith, James A; Terasaki, Mark

    2003-05-01

    Controlled damage by light energy has been a valuable tool in studies of cell function. Here, we show that the Ti:Sapphire laser in a multiphoton microscope can be used to cause localized damage within unlabeled cells or tissues at greater depths than previously possible. We show that the damage is due to a multiphoton process and made wounds as small as 1 microm in diameter 20 microm from the surface. A characteristic fluorescent scar allows monitoring of the damage and identifies the wound site in later observations. We were able to lesion a single axon within a bundle of nerves, locally interrupt organelle transport within one axon, cut dendrites in a zebrafish embryo, ablate a mitotic pole in a sea urchin egg, and wound the plasma membrane and nuclear envelope in starfish oocytes. The starfish nucleus collapsed approximately 1 h after wounding, indicating that loss of compartmentation barrier makes the structure unstable; surprisingly, the oocyte still completed meiotic divisions when exposed to maturation hormone, indicating that the compartmentalization and translocation of cdk1 and its regulators is not required for this process. Multiphoton excitation provides a new means for producing controlled damage deep within tissues or living organisms. PMID:12802057

  14. Controlled Damage in Thick Specimens by Multiphoton ExcitationV?

    PubMed Central

    Galbraith, James A.; Terasaki, Mark

    2003-01-01

    Controlled damage by light energy has been a valuable tool in studies of cell function. Here, we show that the Ti:Sapphire laser in a multiphoton microscope can be used to cause localized damage within unlabeled cells or tissues at greater depths than previously possible. We show that the damage is due to a multiphoton process and made wounds as small as 1 ?m in diameter 20 ?m from the surface. A characteristic fluorescent scar allows monitoring of the damage and identifies the wound site in later observations. We were able to lesion a single axon within a bundle of nerves, locally interrupt organelle transport within one axon, cut dendrites in a zebrafish embryo, ablate a mitotic pole in a sea urchin egg, and wound the plasma membrane and nuclear envelope in starfish oocytes. The starfish nucleus collapsed ?1 h after wounding, indicating that loss of compartmentation barrier makes the structure unstable; surprisingly, the oocyte still completed meiotic divisions when exposed to maturation hormone, indicating that the compartmentalization and translocation of cdk1 and its regulators is not required for this process. Multiphoton excitation provides a new means for producing controlled damage deep within tissues or living organisms. PMID:12802057

  15. Creation of particle-hole superposition states in graphene at multiphoton resonant excitation by laser radiation

    E-print Network

    H. K. Avetissian; A. K. Avetissian; G. F. Mkrtchian; Kh. V. Sedrakian

    2011-12-07

    Nonlinear dynamics of establishment of electron-hole coherent superpositions states in graphene by multiphoton resonant excitation of interband transitions in laser fields is considered. The single-particle time dependent density matrix for such a quantized system is calculated in the multiphoton resonant approximation. The dependence of Rabi oscillations of Fermi-Dirac sea in graphene on the time, momentum, and photon number at multiphoton laser-excitation is analyzed.

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

    NASA Astrophysics Data System (ADS)

    Wang, Kwanghsi; Chu, Shih-I.

    1989-02-01

    We present a detailed two-dimensional (2D) quantal study of the dynamical evolution of microwave-driven Rydberg H atoms. We examine the range of validity of the conventional one-dimensional (1D) models and explore the frequency- and intensity-dependent excitation and ionization mechanisms. The main findings of this paper can be summarized as follows: (i) The excitation spectra of Rydberg H atoms are strongly frequency dependent and can be roughly grouped into three characteristically different regions, each with a different excitation mechanism. In this paper, we emphasize the study of the two major excitation mechanisms: quantum diffusion and multiphoton resonant excitation. The region dominated by quantum diffusion lies in the frequency range ?cexcitation is efficient, leading to the so-called underthreshold photoelectric ionization phenomenon. On the other hand, we found a series of frequency regions (in ?0>?d) where the ionization is mainly due to multiphoton resonant excitation through the more isolated quasienergy avoided crossing points. (ii) The excitation pathways (1D versus 2D) are strongly intensity dependent. For microwave (rescaled) field strength ?0 (??n40) in the range ?cexcitation and ionization proceed through n2>0 ladders rather than the n2=0 ladder, as often assumed in the 1D model. As field strength increases above ?q, however, the 1D model improves significantly. (iii) The quantum localization phenomenon is observed in the classically chaotic region (?c?q. (iv) The stability of quantum diffusive motion is analyzed in terms of the quantal phase-space diagram and the autocorrelation function. The results lend support to the view that quantum mechanics can impose limitations on classical chaotic motion. (v) The way of turning on the field (sin?t or cos?t) does not affect significantly the dynamical evolution of the system. (vi) Finally, a computationally powerful new technique, invoking the use of artificial intelligence algorithms as well as the generalized Van Vleck perturbation theory for effectively reducing the dimensionality of the Floquet matrix, is introduced to facilitate the study of multiphoton resonant excitation of Rydberg atoms.

  17. 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)

  18. All-solid-state ultrafast lasers facilitate multiphoton excitation fluorescence imaging

    Microsoft Academic Search

    David L. Wokosin; Victoria Centonze; John G. White; David Armstrong; Gordon Robertson; Allister I. Ferguson

    1996-01-01

    Improvements in ultrafast laser technology have enabled a new excitation mode for optical sectioning fluorescence microscopy: multiphoton excitation fluorescence imaging. The primary advantages of this technique over laser scanning confocal imaging derive from the localized excitation volume; additional advantages accrue from the longer wavelength of the excitation source. Recent advances in all-solid-state, ultrafast (subpicosecond) laser technology should allow the technique

  19. Multiphoton excitation provides optical sections from deeper within scattering specimens than confocal imaging.

    PubMed Central

    Centonze, V E; White, J G

    1998-01-01

    Multiphoton excitation fluorescence imaging generates an optical section of sample by restricting fluorophore excitation to the plane of focus. High photon densities, achieved only in the focal volume of the objective, are sufficient to excite the fluorescent probe molecules by density-dependent, multiphoton excitation processes. We present comparisons of confocal with multiphoton excitation imaging of identical optical sections within a sample. These side-by-side comparisons of imaging modes demonstrate a significant advantage of multiphoton imaging; data can be obtained from deeper within biological specimens. Observations on a variety of biological samples showed that in all cases there was at least a twofold improvement in the imaging penetration depth obtained with multiphoton excitation relative to confocal imaging. The more pronounced degradation in image contrast deep within a confocally imaged sample is primarily due to scattered emission photons, which reduce the signal and increase the local background as measurements of point spread functions indicated that resolution does not significantly change with increasing depth for either mode of microscopy. Multiphoton imaging does not suffer from degradation of signal-to-background to nearly the same extent as confocal imaging because this method is insensitive to scatter of the emitted signal. Direct detection of emitted photons using an external photodetector mounted close to the objective (possible only in a multiphoton imaging system) improves system sensitivity and the utilization of scattered emission photons for imaging. We demonstrate that this technique provides yet further improvements in the capability of multiphoton excitation imaging to produce good quality images from deeper within tissue relative to confocal imaging. PMID:9746543

  20. Detection sensitivity enhancements for fluorescence imaging with multi-photon excitation microscopy

    Microsoft Academic Search

    David L. Wokosin; W. Brad Amos; John G. White

    1998-01-01

    Multiphoton excitation microscopy (MPEM) offers several distinct advantages over laser scanning confocal microscopy (LSCM). One is that the resolution and the thickness of the optical section are determined by the excitation beam; a confocal detection aperture is therefore unnecessary. This feature allows the photodetector to be relocated from its usual location in the descanned emission beam within a confocal scan

  1. Infrared multiphoton dissociation with a hollow fiber waveguide.

    PubMed

    Drader, Jared J; Hannis, James C; Hofstadler, Steven A

    2003-08-01

    A novel scheme for performing infrared multiphoton dissociation (IRMPD) is presented in which a hollow fiber waveguide (HFWG) is used to transmit IR radiation into the ion storage region of a mass spectrometer. Efficient dissociation of oligonucleotide and protein ions is demonstrated on an ESI-FTICR instrument in which IRMPD is performed in the external ion reservoir and on a quadrupole ion trap. Using a simple optical scheme consisting of a single focusing lens and an x, y translator, the 10.6-microm IR laser beam, initially 3.5 mm in diameter, is focused into the vacuum-sealed HFWG. The small internal diameter and the high transfer efficiency of the waveguide allow IR radiation of high power density to be employed for IRMPD. In studies performed on a quadrupole ion trap, a 500-microm-i.d. waveguide was used as a medium to transmit IR radiation directly through a 700-microm orifice in the ring electrode. Efficient IRMPD of both a 12-mer oligonucleotide and the protein melittin were performed at laser powers of 0.5 and 3.2 W, respectively. PMID:14572028

  2. Efficient generation of moderately high harmonics by multiphoton resonant excitation of atoms

    SciTech Connect

    Avetissian, H. K.; Avchyan, B. R.; Mkrtchian, G. F. [Department of Quantum Electronics, Yerevan State University, 1 A Manukian, Yerevan 375025 (Armenia)

    2008-02-15

    The coherent scattering spectrum of a three-level atom driven by an intense laser field with multiphoton resonant excitation is considered. The spectrum corresponding to harmonic generation is investigated both analytically and numerically for different initial atomic states. The analytical calculations are based on the generalized rotating wave approximation, which allows one to explain obtained spectra containing in general both even and odd harmonics. The results applied to the hydrogen atom show that one can achieve efficient generation of moderately high harmonics using multiphoton resonant excitation by appropriate laser pulses.

  3. Creation of coherent superposition states in hydrogenlike ions via multiphoton resonant excitation

    SciTech Connect

    Avetissian, H. K.; Mkrtchian, G. F.; Poghosyan, M. G. [Department of Quantum Electronics, Yerevan State University, 1 A. Manukian St., Yerevan 375025 (Armenia)

    2006-06-15

    On the basis of the analytical solution of the Dirac equation the resonant multiphoton excitation of highly charged hydrogenlike ions in a strong high-frequency laser field is investigated. It is shown that the dynamics of the relativistic system is equivalent to two independent four-level systems (in the electrical-dipole approximation). The time evolution of the system is found using the nonperturbative resonant approach. We predict that due to multiphoton excitation by an appropriate laser pulse one can achieve various coherent superposition states in atomic or ionic systems with a high nuclear charge.

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

    PubMed Central

    YOUNG, P.A.; CLENDENON, S.G.; BYARS, J.M.; DUNN, K.W.

    2015-01-01

    Summary 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 µm of depth. PMID:21118239

  5. 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.

  6. Multifocal multiphoton excitation and time correlated single photon counting detection for 3-D fluorescence lifetime imaging.

    PubMed

    Kumar, S; Dunsby, C; De Beule, P A A; Owen, D M; Anand, U; Lanigan, P M P; Benninger, R K P; Davis, D M; Neil, M A A; Anand, P; Benham, C; Naylor, A; French, P M W

    2007-10-01

    We report a multifocal multiphoton time-correlated single photon counting (TCSPC) fluorescence lifetime imaging (FLIM) microscope system that uses a 16 channel multi-anode PMT detector. Multiphoton excitation minimizes out-of-focus photobleaching, multifocal excitation reduces non-linear in-plane photobleaching effects and TCSPC electronics provide photon-efficient detection of the fluorescence decay profile. TCSPC detection is less prone to bleaching- and movement-induced artefacts compared to wide-field time-gated or frequency-domain FLIM. This microscope is therefore capable of acquiring 3-D FLIM images at significantly increased speeds compared to single beam multiphoton microscopy and we demonstrate this with live cells expressing a GFP tagged protein. We also apply this system to time-lapse FLIM of NAD(P)H autofluorescence in single live cells and report measurements on the change in the fluorescence decay profile following the application of a known metabolic inhibitor. PMID:19550524

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

    E-print Network

    So, Peter

    -dimensional microscopic biopsy of in vivo human skin: a new technique based on a flexible confocal microscope." J. Micros train of femtosecond laser pulses at 780 nm wavelength. This nonlinear microscopic technique, and E. Gratton, "Optical biopsy of in vivo human skin: multiphoton excitation microscopy," Lasers Med

  8. Arbitrary two-dimensional multiphoton excitation patterns with temporally focused digital holograms

    NASA Astrophysics Data System (ADS)

    Oron, Dan; Papagiakoumou, Eirini; de-Sars, Vincent; Emiliani, Valentina

    2009-02-01

    Multiphoton excitation has recently found application in the fields of bioimaging, uncaging and lithography. In order to fully exploit the advantages of nonlinear excitation, in particular the axial resolution due to nonlinearity, most systems to date operate with point or multipoint excitation, while scanning either the laser beam or the sample to generate the illumination pattern. Here we combine the recently introduced technique of scanningless multiphoton excitation by temporal focusing with recent advances in digital holography to generate arbitrarily shaped, depth resolved, two-dimensional excitation patterns completely without scanning. This is of particular importance in applications requiring uniform excitation of large areas over short time scales, such as neuronal activation by multiphoton uncaging of neurotransmitters. We present an experimental and theoretical analysis of the effect of spatial patterning on the depth resolution achieved in temporal focusing microscopy. It is shown that the depth resolution for holographic excitation is somewhat worse than that achieved for uniform illumination. This is also accompanied by the appearance of a speckle pattern at the temporal focal plane. The origin of the two effects, as well as means to overcome them, are discussed.

  9. 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.

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

    E-print Network

    Van Stryland, Eric

    can be achieved by pulse energy control,6 use of near-field scan- ning microscopes,7 self-focusing,8Near-infrared femtosecond laser machining initiated by ultraviolet multiphoton ionization X. Yu, Q on four-beam laser interference lithography Appl. Phys. Lett. 102, 081903 (2013) Enhanced depth of field

  11. Investigation of the Protonation Site in the Dialanine Peptide by Infrared Multiphoton Dissociation Spectroscopy

    E-print Network

    Paris-Sud XI, Université de

    ) is a very efficient process for deposition of energy in an isolated peptide cation leading to its1 Investigation of the Protonation Site in the Dialanine Peptide by Infrared Multiphoton is routinely performed by means of mass-spectrometry. Following proteolysis, a tryptic digest peptide fragment

  12. 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.

  13. Two-color multiphoton excitation of autoionizing states of atomic iodine

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.

    1986-04-01

    Two-color multiphoton excitation spectra of autoionizing ( 1D 2) ns and nd Rydberg series in atomic iodine are presented in the region of the I +1D 2 ionization threshold. The first laser is used to produce atomic iodine by photodissociation of methyl iodide and to pump the iodine atoms to low-lying ( 1D 2) 6p states via a two-photon transition. The second laser excites single photon transitions from these states to autoionizing Rydberg series, resolved to n ? 35. Extension of this technique for other open shell atoms is discussed.

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

    E-print Network

    Chu, Shih-I; Wang, Kwanghsi

    1989-02-15

    through the more isolated quasienergy avoided crossing points. (ii) The excitation pathways (1D versus 2D) are strongly intensity dependent. For microwave (rescaled) field strength ?0 (??n40) in the range ?c

  15. Population transfer in the multiphoton excitation of molecules

    SciTech Connect

    Graefe, S.; Erdmann, M.; Engel, V. [Institut fuer Physikalische Chemie, Universitaet Wuerzburg, Am Hubland, D-97074 Wuerzburg (Germany)

    2005-07-15

    The laser induced selective preparation of electronically excited molecules is investigated. Therefore, the control fields are determined from the dynamics of the system. By construction, the obtained pulses carry the signature of the electronic and nuclear motion. It is shown that an effective population transfer to different target states is possible. Time-dependent photoelectron spectra are calculated to illustrate that the achieved control yields can be measured directly.

  16. Multiphoton Fluorescence Excitation: New Spectral Windows for Biological Nonlinear Microscopy

    Microsoft Academic Search

    Chris Xu; Warren Zipfel; Jason B. Shear; Rebecca M. Williams; Watt W. Webb

    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,

  17. Multiphoton fluorescence lifetime imaging of human hair.

    PubMed

    Ehlers, Alexander; Riemann, Iris; Stark, Martin; König, Karsten

    2007-02-01

    In vivo and in vitro multiphoton imaging was used to perform high resolution optical sectioning of human hair by nonlinear excitation of endogenous as well as exogenous fluorophores. Multiphoton fluorescence lifetime imaging (FLIM) based on time-resolved single photon counting and near-infrared femtosecond laser pulse excitation was employed to analyze the various fluorescent hair components. Time-resolved multiphoton imaging of intratissue pigments has the potential (i) to identify endogenous keratin and melanin, (ii) to obtain information on intrahair dye accumulation, (iii) to study bleaching effects, and (iv) to monitor the intratissue diffusion of pharmaceutical and cosmetical components along hair shafts. PMID:17152070

  18. Studies of strong-field effects in multiphoton subpicosecond excited plasmas: Soft X-ray fluorescence and propagation

    Microsoft Academic Search

    A. McPherson; T. S. Luk; G. Gibson; J. C. Solem; K. Boyer; C. K. Rhodes

    1989-01-01

    Studies concerning two aspects of the strong-field multiphoton response of matter are discussed, namely, (1) the generation of excited states and (2) the propagation of extremely intense radiation in plasmas. Fluorescence in the 7 – 79 nm region arising from excited ionic states produced in gas targets composed of the rare gases and N2 is examined. Emissions from complex transition

  19. Nonperturbative quantum and classical calculations of multiphoton vibrational excitation and dissociation of Morse molecules^1

    NASA Astrophysics Data System (ADS)

    Dimitriou, K. I.; Mercouris, Th.; Constantoudis, V.; Komninos, Y.; Nicolaides, C. A.

    2006-05-01

    The multiphoton vibrational excitation and dissociation of Morse molecules have been computed nonperturbatively using Hamilton's and Schr?dinger's time-dependent equations, for a range of laser pulse parameters. The time-dependent Schr?dinger equation is solved by the state-specific expansion approach [e.g.,1]. For its solution, emphasis has been given on the inclusion of the continuous spectrum, whose contribution to the multiphoton probabilities for resonance excitation to a number of excited discrete states as well as to dissociation has been examined as a function of laser intensity, frequency and pulse duration. An analysis of possible quantal-classical correspondences for this system is being carried out. We note that distinct features exist from previous classical calculations [2]. For example, the dependence on the laser frequency gives rise to an asymmetry around the red-shifted frequency corresponding to the maximum probability. [1] Th. Mercouris, I. D. Petsalakis and C. A. Nicolaides, J. Phys. B 27, L519 (1994). [2] V. Constantoudis and C. A. Nicolaides, Phys. Rev. E 64, 562112 (2001). ^1This work was supported by the program 'Pythagoras' which is co - funded by the European Social Fund (75%) and Natl. Resources (25%). ^2Physics Department, National Technical University, Athens, Greece.^3Theoretical and Physical Chemistry Institute, Hellenic Research Foundation, Athens, Greece.

  20. Freeform multiphoton excited microfabrication for biological applications using a rapid prototyping CAD-based approach.

    PubMed

    Cunningham, Lawrence P; Veilleux, Matthew P; Campagnola, Paul J

    2006-09-18

    Multiphoton excited polymerization has attracted increasing attention as a powerful 3 dimensional nano/microfabrication tool. The nonlinear excitation confines the fabrication region to the focal volume allowing the potential to achieve freeform fabrication with submicron capabilities. We report the adaptation and use of a computer aided design (CAD) approach, based on rapid prototyping software, which exploits this potential for fabricating with protein and polymers in biologically compatible aqueous environments. 3D structures are drawn in the STL format creating a solid model that can be sliced, where the individual sections are then serially fabricated without overwriting previous layers. The method is shown for potential biological applications including microfluidics, cell entrapment, and tissue engineering. PMID:19529241

  1. 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

  2. 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).

  3. Live tissue intrinsic emission microscopy using multiphoton-excited native fluorescence and second harmonic generation

    NASA Astrophysics Data System (ADS)

    Zipfel, Warren R.; Williams, Rebecca M.; Christie, Richard; Nikitin, Alexander Yu; Hyman, Bradley T.; Webb, Watt W.

    2003-06-01

    Multicolor nonlinear microscopy of living tissue using two- and three-photon-excited intrinsic fluorescence combined with second harmonic generation by supermolecular structures produces images with the resolution and detail of standard histology without the use of exogenous stains. Imaging of intrinsic indicators within tissue, such as nicotinamide adenine dinucleotide, retinol, indoleamines, and collagen provides crucial information for physiology and pathology. The efficient application of multiphoton microscopy to intrinsic imaging requires knowledge of the nonlinear optical properties of specific cell and tissue components. Here we compile and demonstrate applications involving a range of intrinsic molecules and molecular assemblies that enable direct visualization of tissue morphology, cell metabolism, and disease states such as Alzheimer's disease and cancer.

  4. Feasibility of using multiphoton excited tissue autofluorescence for in vivo human histopathology.

    PubMed Central

    Dela Cruz, Johanna M.; McMullen, Jesse D.; Williams, Rebecca M.; Zipfel, Warren R.

    2010-01-01

    Rapid and direct imaging of microscopic tissue morphology and pathology can be achieved by multiphoton imaging of intrinsic tissue fluorophores and second harmonic signals. Engineering parameters for developing this technology for clinical applications include excitation levels and collection efficiencies required to obtain diagnostic quality images from different tissue types and whether these levels are mutagenic. Here we provide data on typical average powers required for high signal-to-noise in vivo tissue imaging and assess the risk potential of these irradiance levels using a mammalian cell gene mutation assay. Exposure times of ~16 milliseconds per cell to 760 nm, ~200 fs raster-scanned laser irradiation delivered through a 0.75 NA objective produced negligible mutagenicity at powers up to about 50 mW. PMID:21258552

  5. Energetics and spin- and ?-doublet selectivity in the infrared multiphoton dissociation HN3(X˜ 1A’)?N2(X 1?+g)+NH(X3??,a 1?): Theory

    Microsoft Academic Search

    Millard H. Alexander; Hans-Joachim Werner; Paul J. Dagdigian

    1988-01-01

    An investigation of the energetics and mechanism of the dissociation of ground state HN3(X˜ 1A’) into ground state N2(X 1?+g)+NH(X 3??) products is presented. This process, which can be induced by multiphoton infrared pumping, occurs through a crossing between the lowest-energy singlet potential energy, which correlates asymptotically with electronically excited NH products (a 1?), and the lowest triplet surface. By

  6. Predissociation and ionization of excited KrXe observed using resonantly enhanced multiphoton ionization-photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.

    1985-05-01

    The heteronuclear rare gas dimer KrXe was examined using resonantly enhanced multiphoton ionization-photoelectron spectroscopy. In addition to photoelectron peaks due to direct photoionization of the KrXe resonant intermediate state, the spectrum shows a number of peaks due to predissociation of the resonant intermediate state followed by photoionization of the excited atomic fragment. The process should be distinguished from the phenomena of hybrid resonances described in ref. [7].

  7. Biosensing and -imaging with enantiomeric luminescent conjugated polythiophenes using multiphoton excitation

    NASA Astrophysics Data System (ADS)

    Lindgren, Mikael; Stabo-Eeg, Frantz; Schnell, Edrun A.; Nilsson, K. Peter R.; Hammarstrom, Per; Inganaes, Olle

    2005-08-01

    We report on the initial time-resolved luminescense and nonlinear absorption properties of two polythiophenes 3-substituted with chiral charged amino acid-derivatized substituents, POWT and POMT. The photo-physical characterization yielded quantum efficiency typically in the range 0.01 - 0.1, however, with two-photon absorption cross-section better than or similar to a typical two-photon reference chromophore, such as fluorescein. They were tested as conformational sensitive optical probes for the recording of pH-induced conformational changes of synthetic peptides, proteins and samples of protein amyloid fibrils characteristic of amyloid related diseases. Particularly, the POMT polyelectrolyte with the L-enantiomeric side chains is shown to favor this induction of well defined structure as judged by the circular dichroic signal as well as a stronger enhancement of luminescense for the L-form over the D-form complex. Furthermore, time-resolved fluorescense and two-photon induced fluorescence both also showed a difference in the complexation with the D and L form. This shows that the multi-photon excitation path can be an efficient means for chiral recognition of biomolecular complexes. It is demonstrated how the conjugated polyelectrolyte L-POMT can be used to spectrally image the formation of amyloid fibrils of insulin using both one- and two-photon absorption based fluorescence imaging.

  8. Infrared multiphoton dissociation of acrolein. Time-resolved observation of CO ( v = 1) IR emission at 4.7 ?m

    NASA Astrophysics Data System (ADS)

    Chowdhury, P. K.; Rama Rao, K. V. S.; Mittal, J. P.

    1994-02-01

    In contrast to the photochemistry of electronically excited acrolein producing vinyl and formyl radicals via C?C bond rupture, multiphoton vibrationally excited molecules undergo concerted dissociation generating CO and ethylene. Vibrational excitation in the CO product is detected immediately following the CO 2 laser pulse by observing IR emission at 4.7 ?m. The decay of the IR emission was studied as a function of acrolein pressure. A vibrational-vibrational relaxation rate constant of CO ( v=1) by acrolein is found to be 1240 ± 200 Torr -1 s -1.

  9. Infrared multiphoton dissociation of methyl nitrite in a molecular beam: Internal states of the nitric oxide fragment

    Microsoft Academic Search

    David S. King; John C. Stephenson

    1985-01-01

    The rotational-, spin-, and lambda doublet-state distributions for nitric oxide (NO) formed in the CO2 laser multiphoton dissociation of methyl nitrite, CH3ONO, in a pulsed molecular beam are reported. Upon methyl nitrite photolysis by temporal square wave infrared laser pulses at 983 cm?1 of 50 ns duration and 800 MW\\/cm2 intensity, the low-lying rotational levels of the nitric oxide fragments

  10. 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.

  11. Design and commissioning of a directly coupled in-vivo multiphoton microscope for skin imaging in humans and large animals

    Microsoft Academic Search

    William J. Mulholland; Mark A. Kendall

    2004-01-01

    The application of near infrared multiphoton excitation to the laser-scanning microscope was first conceived by Denk, Strickler and Webb in 1990. Since then, advances in design have seen the multiphoton laser scanning microscope (MPLSM) applied to a wide range of biological research areas, including skin imaging and vaccine delivery. The technique has the attributes of low phototoxicity, high-resolution functional imaging

  12. Excited state dynamics in SO2. III. An ab initio quantum study of single- and multi-photon ionization

    NASA Astrophysics Data System (ADS)

    Lévêque, Camille; Köppel, Horst; Taïeb, Richard

    2014-05-01

    We present an ab initio quantum study of the photoelectron spectra of sulfur dioxide, based on wavepacket propagations on manifolds of ionic, and excited/Rydberg states. We obtain excellent agreement for two different cases. First, the one photon ionization case where we can reproduce all details of the experimental spectrum and demonstrate the influence of the conical intersection between two of the ionic states. Then the multiphoton ionization regime, in which the dynamics of the wave packet on the two lowest singlet states is directly mapped in the spectra via a pump-probe scheme, as proposed in the experimental companion paper [I. Wilkinson et al., J. Chem. Phys. 140, 204301 (2014)].

  13. 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

    , the intraband nonadiabatic angular couplings are the main driving mechanisms for inducing resonant vibrational–rotational multiphoton transitions. The utility of the method is illustrated by a detailed study of the sequential MPA spectra for 12C?16O molecule...

  14. Multi-photon molecular tagging velocimetry with femtosecond excitation (FemtoMTV)

    E-print Network

    Koochesfahani, Manoochehr M.

    employed for tracer concentration/mixing measurements and temperature mapping, particle image velocimetry is coherent anti-stokes Raman spectroscopy (CARS), a multi-photon process which is utilized in combustion diagnostics for temperature and species selective concen- tration measurements (Begley et al. 1974; Goss et al

  15. Acylated glucosinolates with diverse acyl groups investigated by high resolution mass spectrometry and infrared multiphoton dissociation.

    PubMed

    Bianco, Giuliana; Agerbirk, Niels; Losito, Ilario; Cataldi, Tommaso R I

    2014-04-01

    With the aim of developing a procedure for detecting and identifying intact acylated glucosinolates (a-GLSs) found in trace quantities in natural plant samples, extracts of Barbarea vulgaris seeds were analyzed by reversed-phase liquid chromatography coupled with electrospray ionization and Fourier-transform ion cyclotron resonance mass spectrometry (RPLC-ESI FTICR MS). After a preliminary optimization of fragmentation conditions, based on a non-acylated parent glucosinolate (glucobarbarin) and three previously identified a-GLSs (the 6'-isoferuloyl esters of glucobarbarin, gluconasturtiin and glucobrassicin), infrared multiphoton dissociation (IRMPD) was employed for a tandem MS-based elucidation of the molecular structures of novel a-GLSs. As a result, three acylated derivatives of glucobarbarin, esterified at the thioglucose moiety with a coumaric acid isomer, sinapic acid or an isomer and a dimethoxycinnamic acid isomer, were identified. In addition, a further acylated glucosinolate was tentatively identified as the isoferuloyl ester of an unidentified hydroxylic derivative of glucobarbarin. This is the first demonstration of diversity in the acyl moieties of thioglucose-acylated glucosinolates, which may reflect the substrate specificity of the endogenous acyl transferase. As expected, 6'-isoferuloyl-glucobarbarin was detected as the main acylated GLS in extracts of B. vulgaris seeds. A quantitative estimate suggested that non-isoferuloyl substituted glucobarbarins correspond to ca. 0.026% of the level of 6'-isoferuloyl glucobarbarin. The formation of an uncommon distonic radical anion, most likely generated in the gas phase upon methyl radical (CH3·) loss from the isoferuloyl anion, is demonstrated. PMID:24512839

  16. Excited state dynamics in SO2. III. An ab initio quantum study of single- and multi-photon ionization.

    PubMed

    Lévêque, Camille; Köppel, Horst; Taïeb, Richard

    2014-05-28

    We present an ab initio quantum study of the photoelectron spectra of sulfur dioxide, based on wavepacket propagations on manifolds of ionic, and excited/Rydberg states. We obtain excellent agreement for two different cases. First, the one photon ionization case where we can reproduce all details of the experimental spectrum and demonstrate the influence of the conical intersection between two of the ionic states. Then the multiphoton ionization regime, in which the dynamics of the wave packet on the two lowest singlet states is directly mapped in the spectra via a pump-probe scheme, as proposed in the experimental companion paper [I. Wilkinson et al., J. Chem. Phys. 140, 204301 (2014)]. PMID:24880276

  17. Lung alveolar wall disruption in three-dimensional space identified using second-harmonic generation and multiphoton excitation fluorescence

    NASA Astrophysics Data System (ADS)

    Abraham, Thomas; Hogg, James

    2010-02-01

    Second harmonic generation and multiphoton excited fluorescence microscopy methods were used to examine structural remodeling of the extracellular matrix in human lung alveolar walls undergoing emphysematous destruction. Fresh lung samples removed from a patient undergoing lung transplantation for very severe chronic obstructive pulmonary disease were compared to similar samples from an unused donor lung that served as a control. The generated spatially resolved 3D images show the spatial distribution of collagen, elastin and other endogenously fluorescent tissue components such as macrophages. In the case of control lung tissue, we found well ordered alveolar walls with composite type structure made up of collagen matrix and relatively fine elastic fibers. In contrast, lung tissue undergoing emphysematous destruction was highly disorganized with increased alveolar wall thickness compared to control lung tissue.

  18. Energetics and spin selectivity in the infrared multiphoton dissociation HN3(X˜1A')?N2(X1?g+)+NH(X3?-,a1?)

    NASA Astrophysics Data System (ADS)

    Alexander, Millard H.; Dagdigian, Paul J.

    1989-10-01

    The dissociation of HN3(X˜1A') into ground state N2(X1?+g) and the NH radical in its ground (X3?-) or first excited (a1?) electron state, studied experimentally by Stephenson, King, Cassassa and Foy at NBS using infrared multiphoton and overtone pumping, involves a crossing between the lowest energy singlet and triplet HN3 potential energy surfaces. Ab initio CASSCF and MCSCF calculations have been used to locate the transition states for both channels. The symmetry of the ground state HN3 wavefunctions as well as of the relevant spin-orbit Hamiltonian with respect to reflection of the spatial and spin components of all the electrons in the plane of the molecule implies that NH products can be formed only in states in which the wavefunction (electronic+rotational) is also symmetric with respect to this operation. This implies that for NH in the X3?- electronic state only the F1 and F3 multiplets will be populated in the dissociation process, as seen experimentally.

  19. 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. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)] [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    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.

  20. Laser-driven electron dynamics for circular dichroism in mass spectrometry: from one-photon excitations to multiphoton ionization.

    PubMed

    Kröner, Dominik

    2015-07-15

    The distinction of enantiomers is a key aspect of chemical analysis. In mass spectrometry the distinction of enantiomers has been achieved by ionizing the sample with circularly polarized laser pulses and comparing the ion yields for light of opposite handedness. While resonant excitation conditions are expected to be most efficient, they are not required for the detection of a circular dichroism (CD) in the ion yield. However, the prediction of the size and sign of the circular dichroism becomes challenging if non-resonant multiphoton excitations are used to ionize the sample. Employing femtosecond laser pulses to drive electron wavepacket dynamics based on ab initio calculations, we attempt to reveal underlying mechanisms that determine the CD under non-resonant excitation conditions. Simulations were done for (R)-1,2-propylene oxide, using time-dependent configuration interaction singles with perturbative doubles (TD-CIS(D)) and the aug-cc-pVTZ basis set. Interactions between the electric field and the electric dipole and quadrupole as well as between the magnetic field and the magnetic dipole were explicitly accounted for. The ion yield was determined by treating states above the ionization potential as either stationary or non-stationary with energy-dependent lifetimes based on an approved heuristic approach. The observed population dynamics do not allow for a simple interpretation, because of highly non-linear interactions. Still, the various transition pathways are governed by resonant enantiospecific n-photon excitation, with preferably high transition dipole moments, which eventually dominate the CD in the ionized population. PMID:26151731

  1. Volume 59, number1 CHEMICAL PHYSICSLETlXRS 1 November1978 PRODUCTION OF EXCITED METAL ATOMS BY UV MULTIPHOTON DlSSOCiATION

    E-print Network

    Zare, Richard N.

    MULTIPHOTON DlSSOCiATION OF METAL ALKYL AND METAL CARBONYL COMPOUNDS 2. KARNY, R N&WAN and R.N. ZARFL atoms by irradiating the vapors of various metal alkyls and carbonyls with the output of an ArF (1930 A) or KrF (2490 A) laser. This technique has been used to form highly excited metal atoms of iron, lead

  2. Generation of electronically excited products in the multiphoton dissociation of phosgene at 193 nm

    NASA Astrophysics Data System (ADS)

    Wilson, M. W.; Rothschild, M.; Rhodes, C. K.

    1983-07-01

    Observation of electronically excited Cl2 upon dissociation of phosgene is reported. Evidence for the formation of neutral fragments arising from states embedded in the ionization continuum is discussed.

  3. In vivo multiphoton nanosurgery on cortical

    E-print Network

    Sandini, Giulio

    neurons. Multiphoton nanosurgery has been performed in worms to study axon regeneration6 and dissectIn vivo multiphoton nanosurgery on cortical neurons Leonardo Sacconi,a,b,, * Rodney P. O exploit the spatial localization of multiphoton excitation to perform selective lesions on the neuronal

  4. 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.

  5. Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

    NASA Astrophysics Data System (ADS)

    Linz, Norbert; Freidank, Sebastian; Liang, Xiao-Xuan; Vogelmann, Hannes; Trickl, Thomas; Vogel, Alfred

    2015-04-01

    Investigation of the wavelength dependence (725-1025 nm) of the threshold for nanosecond optical breakdown in water revealed steps consistent with breakdown initiation by multiphoton ionization, with an initiation energy of about 6.6 eV. This value is considerably smaller than the autoionization threshold of about 9.5 eV, which can be regarded as band gap relevant for avalanche ionization. Breakdown initiation is likely to occur via excitation of a valence band electron into a solvated state, followed by rapid excitation into the conduction band. Theoretical analysis based on these assumptions suggests that the seed electron density required for initiating avalanche ionization amounts to 2.5 ×1015c m-3 at 725 nm and drops to 1.1 ×1012c m-3 at 1025 nm. These results demand changes of future breakdown modeling for water, including the use of a larger band gap than previously employed, the introduction of an intermediate energy level for initiation, and consideration of the wavelength dependence of seed electron density.

  6. IR multiphoton excitation of SF{sub 6} molecules subliming from the surface of (CO{sub 2}){sub N} nanoparticles in a cluster beam

    SciTech Connect

    Makarov, Grigorii N; Petin, A N [Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

    2009-11-30

    This work examines IR multiphoton excitation of SF{sub 6} molecules subliming from the surface of (CO{sub 2}){sub N} van der Waals clusters (nanoparticles) in a cluster beam (the number of monomers per cluster, N{>=}10{sup 2}). The SF{sub 6} molecules are captured by clusters when a cluster beam intersects a molecular beam and sublime from the cluster surface after a certain time, carrying information about the velocity and temperature (internal energy) of the clusters. The multiphoton absorption spectra of the SF{sub 6} molecules subliming from the cluster surface are markedly narrower than those of the SF{sub 6} molecules in the parent, gas-dynamically cooled molecular beam, indicating that the vibrational temperature of the molecules subliming from the cluster surface is lower. Therefore, the proposed technique can be used to produce strongly vibrationally cooled molecules, which are of interest for a number of applications, in particular for achieving high-selectivity IR multiphoton excitation and isotopically selective dissociation of molecules. (nonlinear optical phenomena)

  7. Energetics and spin- and ?-doublet selectivity in the infrared multiphoton dissociation DN3?DN(X 3??, a 1?)+N2(X 1?+g): Experiment

    Microsoft Academic Search

    John C. Stephenson; Michael P. Casassa; David S. King

    1988-01-01

    Multiphoton vibrational excitation of deuterated hydrazoic acid, DN3, by a CO2 laser (I=10 GW\\/cm2) leads to dissociation forming DN in both X 3?? (spin forbidden) and a 1? (spin allowed) electronic states. Under collisionless conditions, the nascent DN fragments were probed via laser induced fluorescence, to determine initial product state distributions. The DN(X 3??) molecules are formed predominantly in the

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

    PubMed

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

    2015-01-01

    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. PMID:25407414

  9. 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.

  10. Infrared light excites cells by changing their electrical capacitance

    PubMed Central

    Shapiro, Mikhail G.; Homma, Kazuaki; Villarreal, Sebastian; Richter, Claus-Peter; Bezanilla, Francisco

    2012-01-01

    Optical stimulation has enabled important advances in the study of brain function and other biological processes, and holds promise for medical applications ranging from hearing restoration to cardiac pace making. In particular, pulsed laser stimulation using infrared wavelengths >1.5 ?m has therapeutic potential based on its ability to directly stimulate nerves and muscles without any genetic or chemical pre-treatment. However, the mechanism of infrared stimulation has been a mystery, hindering its path to the clinic. Here we show that infrared light excites cells through a novel, highly general electrostatic mechanism. Infrared pulses are absorbed by water, producing a rapid local increase in temperature. This heating reversibly alters the electrical capacitance of the plasma membrane, depolarizing the target cell. This mechanism is fully reversible and requires only the most basic properties of cell membranes. Our findings underscore the generality of pulsed infrared stimulation and its medical potential. PMID:22415827

  11. Differentiation and Distributions of DNA/Cisplatin Crosslinks by Liquid Chromatography-Electrospray Ionization-Infrared Multiphoton Dissociation Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, Zhe; Brodbelt, Jennifer S.

    2014-01-01

    Liquid chromatography-electrospray ionization-infrared multiphoton dissociation (IRMPD) mass spectrometry was developed to investigate the distributions of intrastrand crosslinks formed between cisplatin and two oligodeoxynucleotides (ODNs), d(A1T2G3G4G5T6A7C8C9C10A11T12) (G3-D) and its analog d(A1T2G3G4G5T6T7C8C9C10A11T12) (G3-H), which have been reported to adopt different secondary structures in solution. Based on the formation of site-specific fragment ions upon IRMPD, two isobaric crosslink products were differentiated for each ODN. The preferential formation of G3G4 and G4G5 crosslinks was determined as a function of reaction conditions, including incubation temperature and presence of metal ions. G3-D consistently exhibited a greater preference for formation of the G4G5 crosslink compared with the G3-H ODN. The ratio of G3G4:G4G5 crosslinks increased for both G3-D and G3-H at higher incubation temperatures or when metal salts were added. Comparison of the IRMPD fragmentation patterns of the unmodified ODNs and the intramolecular platinated crosslinks indicated that backbone cleavage was significantly suppressed near the crosslink.

  12. Differentiation and Distributions of DNA/Cisplatin Crosslinks by Liquid Chromatography-Electrospray Ionization-Infrared Multiphoton Dissociation Mass Spectrometry

    PubMed Central

    Xu, Zhe; Brodbelt, Jennifer S.

    2013-01-01

    Liquid chromatography-electrospray ionization-infrared multiphoton dissociation (IRMPD) mass spectrometry was developed to investigate the distributions of intrastrand crosslinks formed between cisplatin and two oligodeoxynucleotides (ODNs), d(A1T2G3G4G5T6A7C8C9C10A11T12) (G3-D) and its analog d(A1T2G3G4G5T6T7C8C9C10A11T12) (G3-H), that have been reported to adopt different secondary structures in solution. Based on the formation of site-specific fragment ions upon IRMPD, two isobaric crosslink products were differentiated for each ODN. The preferential formation of G3G4 and G4G5 crosslinks was determined as a function of reaction conditions, including incubation temperature and presence of metal ions. G3-D consistently exhibited a greater preference for formation of the G4G5 crosslink compared to the G3-H ODN. The ratio of G3G4:G4G5 crosslinks increased for both G3-D and G3-H at higher incubation temperatures or when metal salts were added. Comparison of the IRMPD fragmentation patterns of the unmodified ODNs and the intramolecular platinated crosslinks indicated that backbone cleavage was significantly suppressed near the crosslink. PMID:24135806

  13. 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.

  14. 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.

  15. Role of resonance-enhanced multiphoton excitation in high-harmonic generation of N2: A time-dependent density-functional-theory study

    NASA Astrophysics Data System (ADS)

    Chu, Xi; Groenenboom, Gerrit C.

    2013-01-01

    A minimum at ˜39 eV is observed in the high-harmonic-generation spectra of N2 for several laser intensities and frequencies. This minimum appears to be invariant for different molecular orientations. We reproduce this minimum for a set of laser parameters and orientations in time-dependent density-functional-theory calculations, which also render orientation-dependent maxima at 23-26 eV. Photon energies of these maxima overlap with ionization potentials of excited states observed in photoelectron spectra. Time profile analysis shows that these maxima are caused by resonance-enhanced multiphoton excitation. We propose a four-step mechanism, in which an additional excitation step is added to the well-accepted three-step model. Excitation to a linear combination of Rydberg states c4'1?u+ and c31?u gives rise to an orientation-invariant minimum analogous to the “Cooper minimum” in argon. When the molecular axis is parallel to the polarization direction of the field, a radial node goes through the atomic centers, and hence the Cooper-like minimum coincides with the minimum predicted by a modified two-center interference model that considers the de-excitation of the ion and symmetry of the Rydberg orbital.

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

    E-print Network

    Mazur, Eric

    's cheerful attitude was better that any advice when I was lost in the dark of research. Special thanks. This information is complemented by the CARS measurements which make it possible to perform state-specific studies

  17. Pressure and power dependence in the infrared laser photolysis of 1-chloro-1-fluoroethylene: experiment and modeling calculations

    SciTech Connect

    Nogar, N.S.; Jalenak, W.A.

    1981-01-01

    Dissociation of 1-chloro-1-fluoroethylene following infrared multiphoton excitation was monitored via infrared fluorescence of the products, either HCl* or HF*. Total dissociation yield and branching ratio were monitored as functions of, respectively, pressure and photolytic intensity. A rate equations model of the excitation and dissociation process is shown to be consistent with both sets of data.

  18. Shock excited far-infrared molecular emission around T Tau

    E-print Network

    L. Spinoglio; T. Giannini; B. Nisini; M. E. van den Ancker; E. Caux; A. M. Di Giorgio; D. Lorenzetti; F. Palla; S. Pezzuto; P. Saraceno; H. A. Smith; G. J. White

    1999-09-29

    The first complete far-infrared spectrum of T Tau has been obtained with the LWS spectrometer on-board the Infrared Space Observatory, which detected strong emission from high-J (J=14-25) CO, para- and ortho-H2O and OH transitions over the wavelength range from 40 to 190 micron. Most of the observed molecular emission can be explained by a single emission region at T~300-900 K and n(H_2)~10^(5-6) cm^(-3),with a diameter of about 2-3 arcsec. This corresponds to a very compact region of 300-400 AU at the distance of 140 pc. An higher temperature component seems to be needed to explain the highest excitation CO and water lines. We derive a water abundance of 1-7x10^(-5) and an OH abundance of ~3x10^(-5) with respect to molecular hydrogen, implying water and OH enhancements by more than a factor of 10 with respect to the expected ambient gas abundance. The observed cooling in the various species amounts to 0.04 L(sun),comparable to the mechanical luminosity of the outflow, indicating that the stellar winds could be responsible of the line excitation through shocks. In order to explain the observed molecular cooling in T Tau in terms of C-type shock models, we hypothesise that the strong far-ultraviolet radiation field photodissociates water in favour of OH. This would explain the large overabundance of OH observed. The estimated relatively high density and compactness of the observed emission suggest that it originates from the shocks taking place at the base of the molecular outflow emission, in the region where the action of the stellar winds from the two stars of the binary system is important.

  19. Pulse-shaping and Fourier Transform Techniques in Multiphoton Microscopy

    Microsoft Academic Search

    Jennifer Ogilvie; Delphine D'Barre; Emmanuel Beaurepaire; Antigoni Alexandrou; Manuel Joffre

    2006-01-01

    Multiphoton microscopy is an important tool that is increasingly used in biological research. The ease with which broadband femtosecond pulses can be created and manipulated has opened up new directions for enhancing multiphoton microscopy. In particular, pulse-shaping techniques can tailor broadband light to selectively excite fluorescent species.[1] Here we demonstrate the use of pulse-shaped excitation to enhance multiphoton fluorescence imaging

  20. 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

  1. A Monte Carlo wave function study of the effect of collisions on the coherent multiphoton excitation of SF6

    NASA Astrophysics Data System (ADS)

    Mitra, S. S.; Bhattacharyya, S. S.

    1994-12-01

    Collisional interruption of coherent excitation of SF6 in the lower discrete region of its laser absorbing mode (?3) have been studied using the recently developed quantum Monte Carlo wave function (QMCWF) method. The usual pure pump mode description up to 3?3 and complete mixing of all modes (QC) above it have been assumed. The rotational and anharmonic splitting of the vibrational states upto 3?3 are taken into account but splitting due to tensor interaction terms are neglected. Excitation to QC is represented by irreversible leakage from the coherent ladder modeled by an imaginary term in the Hamiltonian of the coherently excited vibrational rotational levels. QMCWF study has been carried out at the laser frequency 942.8 cm-1 for which the local time average populations in the intermediate excited vibrational states are found to be negligible. Large leakage occurs only from narrow band of ground rotational states due to 3 photon resonances but their number increases with increasing intensity. Two different collisional energy transfer models, one obeying symmetry imposed restrictions and propensity rule, and the other free from such restrictions except the fact that collisions restore the thermal distribution, have been used. Results show different pressure effects at different temperature and for different intensities. However, the two different models used for collisional rotational transition probabilities give similar enhancement of leakage at high intensities.

  2. Excited-state absorption in high-power mid-infrared quantum cascade lasers

    Microsoft Academic Search

    Y. Dikmelik; J. B. Khurgin; A. J. Hoffman; S. S. Howard; K. J. Franz; C. F. Gmachl

    2008-01-01

    The loss due to excited-state absorption into the continuum was calculated for high-power mid-infrared quantum cascade lasers. We find this loss to be a significant fraction of the gain at the laser wavelength.

  3. Control of multiphoton and avalanche ionization using an ultraviolet-infrared pulse train in femtosecond laser micro/nano-machining of fused silica

    NASA Astrophysics Data System (ADS)

    Yu, Xiaoming; Bian, Qiumei; Chang, Zenghu; Corkum, P. B.; Lei, Shuting

    2014-03-01

    We report on the experimental results of micro- and nanostructures fabricated on the surface of fused silica by a train of two femtosecond laser pulses, a tightly focused 266 nm (ultraviolet, UV) pulse followed by a loosely focused 800 nm (infrared, IR) pulse. By controlling the fluence of each pulse below the damage threshold, micro- and nanostructures are fabricated using the combined beams. The resulting damage size is defined by the UV pulse, and a reduction of UV damage threshold is observed when the two pulses are within ~ 1 ps delay. The effects of IR pulse duration on the UV damage threshold and shapes are investigated. These results suggest that the UV pulse generates seed electrons through multiphoton absorption and the IR pulse utilizes these electrons to cause damage by avalanche process. A single rate equation model based on electron density can be used to explain these results. It is further demonstrated that structures with dimensions of 124 nm can be fabricated on the surface of fused silica using 0.5 NA objective. This provides a possible route to XUV (or even shorter wavelength) laser nano-machining with reduced damage threshold.

  4. Calculating singlet excited states: Comparison with fast time-resolved infrared spectroscopy of coumarins.

    PubMed

    Hanson-Heine, Magnus W D; Wriglesworth, Alisdair; Uroos, Maliha; Calladine, James A; Murphy, Thomas S; Hamilton, Michelle; Clark, Ian P; Towrie, Michael; Dowden, James; Besley, Nicholas A; George, Michael W

    2015-04-21

    In contrast to the ground state, the calculation of the infrared (IR) spectroscopy of molecular singlet excited states represents a substantial challenge. Here, we use the structural IR fingerprint of the singlet excited states of a range of coumarin dyes to assess the accuracy of density functional theory based methods for the calculation of excited state IR spectroscopy. It is shown that excited state Kohn-Sham density functional theory provides a high level of accuracy and represents an alternative approach to time-dependent density functional theory for simulating the IR spectroscopy of singlet excited states. PMID:25903878

  5. Calculating singlet excited states: Comparison with fast time-resolved infrared spectroscopy of coumarins

    NASA Astrophysics Data System (ADS)

    Hanson-Heine, Magnus W. D.; Wriglesworth, Alisdair; Uroos, Maliha; Calladine, James A.; Murphy, Thomas S.; Hamilton, Michelle; Clark, Ian P.; Towrie, Michael; Dowden, James; Besley, Nicholas A.; George, Michael W.

    2015-04-01

    In contrast to the ground state, the calculation of the infrared (IR) spectroscopy of molecular singlet excited states represents a substantial challenge. Here, we use the structural IR fingerprint of the singlet excited states of a range of coumarin dyes to assess the accuracy of density functional theory based methods for the calculation of excited state IR spectroscopy. It is shown that excited state Kohn-Sham density functional theory provides a high level of accuracy and represents an alternative approach to time-dependent density functional theory for simulating the IR spectroscopy of singlet excited states.

  6. Multiphoton fluorescence microspectroscopy

    NASA Astrophysics Data System (ADS)

    Kao, Fu-Jen; Lin, Bai-Ling; Cheng, Ping C.

    2000-05-01

    The intrinsic confined photo-interacting volume in multi- photon fluorescence microscopy provides the possibility of obtaining fluorescence spectrum from specific cellular structure in a tissue. In this article, we demonstrated that it is feasible to obtain useful two-photon pumped fluorescence spectrum from cell wall and single chloroplast. The difference in fluorescence spectra obtained with single- and two-photon excitation indicates that a significant shift in fluorescence maximum may occur due to the non-linear nature of excitation. Therefore, in order to properly interpret two-photon fluorescence micrographs, it is important to characterize the fluorescence spectrum of the specimen and the commonly used fluorescence probes. The fluorescence spectra will in turn be useful in the selection of filter sets in multi-photon fluorescence microscopy.

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

    E-print Network

    Krishna, Sanjay

    photodetector (QDIP) by the excitation of surface plasma waves (SPWs) using a metal photonic crystal (MPC to the SPWs excited at the MPC/detector interface by incident photons. The SPW resonance wavelength, E. A. Kort, K. B. Crozier, and F. Capasso, "Plasmonic laser antenna," Appl. Phys. Lett. 89

  8. Multiphoton entanglement

    NASA Astrophysics Data System (ADS)

    Bourennane, Mohamed; Eibl, Manfred; Gaertner, Sascha; Kiesel, Nicolai; Kurtsiefer, Christian; Zukowski, Marek; Weinfurter, Harald

    2002-09-01

    Multiphoton entanglement is the basis of many quantum communication schemes, quantum cryptographic protocols, and fundamental tests of quantum theory. Spontaneous parametric down-conversion is the most effective source for polarization entangled photon pairs. Here we show, that a entangled 4-photon state can be directly created by parametric down-conversion. This state exhibit perfect quantum correlations and a high robustness of entanglement against photon loss. We have used this state for four-particle test of local realistic theories. Therefore this state can be used for new types of quantum communication. We also report on possibilities for the experimentally realization of a 3-photon entangled state, the so called W-state, and discuss some of its properties.

  9. 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.

  10. Multiphoton spectroscopy of Rydberg states of small molecules

    SciTech Connect

    Pratt, Stephen T.; McCormack, E. F.; Dehmer, Joseph L.; Dehmer, Patricia M.

    1990-09-01

    Multiphoton ionization techniques provide a versatile means for studying highly excited states of atoms and molecules and provide a valuable complement to traditional techniques based on single-photon absorption and ionization studies. In this paper we present the results of new multiphoton ionization studies of molecular nitrogen and molecular oxygen that serve to illustrate the power of these techniques. 30 refs., 3 figs.

  11. Three-dimensional multiphoton autofluorescence spectral imaging of live tissues

    NASA Astrophysics Data System (ADS)

    Palero, Jonathan A.; de Bruijn, Henriëtte S.; van der Ploeg van den Heuvel, Angélique; Sterenborg, Henricus J. C. M.; Gerritsen, Hans C.

    2006-04-01

    We combined a homebuilt multiphoton microscope and a prism-CCD based spectrograph to develop a spectral imaging system capable of imaging deep into live tissues. The spectral images originate from the two-photon autofluorescence of the tissue and second harmonic signal from the collagen fibers. A highly penetrating near-infrared light is used to excite the endogenous fluorophores via multiphoton excitation enabling us to produce high quality images deep into the tissue. We were able to produce 100-channel (330 nm to 600 nm) autofluorescence spectral images of live skin tissues in less than 2 minutes for each xy-section. The spectral images rendered in RGB (real) colors showed green hair shafts, blue cells, and purple collagen. Analysis on the optical signal degradation with increasing depth of the collagen second-harmonic signal showed 1) exponential decay behavior of the intensity and 2) linear broadening of the spectrum. This spectral imaging system is a promising tool for both in biological applications and biomedical applications such as optical biopsy.

  12. Improved multiphoton ultraviolet upconversion photoluminescence in ultrasmall core-shell nanocrystals.

    PubMed

    Tao, Lili; Zhou, Bo; Jin, Wei; Chai, Yang; Tang, Chun-Yin; Tsang, Yuen H

    2014-11-01

    Near-infrared to ultraviolet multiphoton upconversion photoluminescence in ultrasmall Tm3+/Yb3+-codoped CaF2 nanocrystals (?6.7??nm in size) was observed and further significantly enhanced by growing an active shell of NaYF4:Yb3+. Owing to the active shell, the lanthanide emitters inside the core are effectively prevented from the surface quenchers, and the excitation energy is absorbed more efficiently via the additional luminescence sensitizer Yb3+ embedded in the shell. The details of underlying physics were investigated and discussed. The results present a good ultrasmall luminescent material system for achieving efficient multiphoton upconversion, which shows great potential in versatile industrial and biological applications. PMID:25361330

  13. Multiphoton luminescence imaging of chemically functionalized multi-walled carbon nanotubes in cells and solid tumors.

    PubMed

    Rubio, N; Hirvonen, L M; Chong, E Z; Wang, J T W; Bourgognon, M; Kafa, H; Hassan, H A F M; Al-Jamal, W T; McCarthy, D; Hogstrand, C; Festy, F; Al-Jamal, K T

    2015-05-21

    The intrinsic nonlinear photoluminescence (PL) property of chemically functionalized multi-walled nanotubes MWNTs (f-MWNTs) is reported in this study. f-MWNTs are imaged in fixed lung epithelial cancer cells (A549) and Kupffer cells in vitro, and in subcutaneously implanted solid tumors in vivo, for the first time, using multiphoton PL and fluorescence lifetime imaging (FLIM). Multiphoton imaging in the near-infrared excitation region (?750-950 nm), employed in this study in a label-free manner, provides sensitivity and resolution optimal to track f-MWNTs within intra-cellular compartments and facilitates tumour imaging and sentinel lymph node tracking in vivo. Wider applications include employing this technique in live imaging of f-MWNTs in biological milieu to facilitate image-guided drug delivery. PMID:25959229

  14. Energetics and spin- and ?-doublet selectivity in the infrared multiphoton dissociation HN3(X-tilde 1Ascript) --> N2(X 1Sigma + g)+NH(X 3Sigma - ,a 1?): Theory

    NASA Astrophysics Data System (ADS)

    Alexander, Millard H.; Werner, Hans-Joachim; Dagdigian, Paul J.

    1988-08-01

    An investigation of the energetics and mechanism of the dissociation of ground state HN3(X˜ 1A') into ground state N2(X 1?+g)+NH(X 3?-) products is presented. This process, which can be induced by multiphoton infrared pumping, occurs through a crossing between the lowest-energy singlet potential energy, which correlates asymptotically with electronically excited NH products (a 1?), and the lowest triplet surface. By means of ab initio CASSCF and MCSCF-CI calculations we have determined that the geometry at the minimum singlet-triplet crossing corresponds to an approximately linear N3 backbone with a perpendicular NH bond. The interior N-N distance is ˜3.6 bohr. This transition state lies ˜12 500 cm-1 above the energy of X˜ 1A' state of HN3 at the experimental equilibrium geometry. Since the N-N and N-H bonds are perpendicular at this transition state, there will be no torques tending to twist the system out of a planar geometry. The crucial singlet-triplet coupling occurs because the HN3 wave function in the region of this transition state can be considered an equal admixture of N2(X)?NH(a 1?) and N2(X)?NH(b 1?+). Since the ground state HN3 wave function as well as the relevant spin-orbit Hamiltonian are symmetric with respect to reflection of the spatial and spin components of all the electrons in the plane of the molecule, and since the NH fragment must rotate in the plane of the initital HN3 molecule if the dissociation is planar, NH products can be formed only in states in which the wave function (electronic+rotational) is also symmetric with respect to this operation. For a molecule in a 3?- electronic state the wave functions in only the F1 and F3 multiplets will be symmetric so that one would expect population in only the F1 and F3 levels. A similar symmetry argument implies that the NH products formed in the lowest spin-allowed channel [N2(X 1?+g)+NH(a 1?)] will be found predominantly in the ?(A') ?-doublet state, which is symmetric with respect to reflection of the spatial coordinates of the electrons in the plane of rotation. This spin- and ?-doublet selectivity has been found experimentally by Stephenson, Casassa, and King (accompanying article). The implications of similar spin selectivity in other photodissociation processes leading to molecules in 3?- states, e.g., SO(X 3?-) and O2(X 3?-g), are also considered.

  15. Non-destructive Testing by Infrared Thermography Under Random Excitation and ARMA Analysis

    NASA Astrophysics Data System (ADS)

    Bodnar, J. L.; Nicolas, J. L.; Candoré, J. C.; Detalle, V.

    2012-11-01

    Photothermal thermography is a non-destructive testing (NDT) method, which has many applications in the field of control and characterization of thin materials. This technique is usually implemented under CW or flash excitation. Such excitations are not adapted for control of fragile materials or for multi-frequency analysis. To allow these analyses, in this article, the use of a new control mode is proposed: infrared thermography under random excitation and auto regressive moving average analysis. First, the principle of this NDT method is presented. Then, the method is shown to permit detection, with low energy constraints, of detachments situated in mural paintings.

  16. FDTD/TDSE study of surface-enhanced infrared absorption by metal nanoparticles.

    SciTech Connect

    Chang, S.-H.; Schatz, G. C.; Gray, S. K.; Chemistry; Northwestern Univ.; National Cheng-Kung Univ.

    2006-01-01

    We study surface-enhanced infrared absorption, including multiphoton processes, due to the excitation of surface plasmons on metal nanoparticles. The time-dependent Schroedinger equation and finite-difference time-domain method are self-consistently coupled to treat the problem.

  17. Multiphoton imaging of corneal tissue with near-infrared femtosecond laser pulses: corneal optical tomography and its use in refractive surgery

    NASA Astrophysics Data System (ADS)

    Wang, Bao-Gui; Koenig, Karsten; Riemann, Iris; Schubert, Harald; Halbhuber, Karl-Juergen

    2006-02-01

    The two-photon-mediated autofluorescence and second harmonic generation (SHG) are acting as a novel diagnostic tool to perform tissue optical tomography with submicron resolution. The three-dimensional corneal ultrastructure of whole depth can be probed without any staining or mechanical slicing. Compared with photodisruptive surgical effects occurring at TW/cm2 light intensity, multiphoton imaging can be induced at MW-GW/cm2 photon intensity. The multiphoton microscopy based on nonlinear absorption of femtosecond laser pulses at the wavelength of 715-930nm emitted from solid-state Ti: sapphire system is being used as a precise non-invasive monitoring tool to determine the interest of region, to visualize and to verify the outcomes in the invivo intrastromal laser nanosurgery. More interesting, the activated keratocytes have been also observed in-vivo 24 hours after the laser nanosurgery with this system. Overall, these data suggest that multiphoton microscopy is a highly sensitive and promising technique for studying the morphometric properties of the microstructure of the corneal tissue and for assessing the intrastromal nanosurgery. With the help of the multiphoton-mediated imaging, the next generation of laser refractive surgery approaches based on the nonamplified femtosecond lasers with higher precision and less complications are being evaluated systematically.

  18. Ultraviolet upconversion fluorescence in rare-earth-ion-doped Y2O3 induced by infrared diode laser excitation.

    PubMed

    Chen, G Y; Somesfalean, G; Zhang, Z G; Sun, Q; Wang, F P

    2007-01-01

    Room-temperature ultraviolet emission of Tm(3+) ions at 298 ((1)I(6)-->(3)H(6)), 364 ((1)D(2)-->(3)H(6)), and 391 nm ((1)I(6)-->(3)H(5)) was obtained in Y(2)O(3):Yb(3+)-Tm(3+) by continuous-wave diode laser excitation of 980 nm. Power dependence analysis demonstrates that five- and six-photon upconversion processes populate the (1)D(2) and (1)I(6) states, respectively. We believe that the (1)D(2) population originates from the cross relaxation (1)G(4)+(3)F(4)-->(3)H(4)+(1)D(2) of the Tm(3+) ions, while subsequent energy transfer from Yb(3+) to Tm(3+) excites the (1)D(2) state to the upper (1)I(6) state. High multiphoton-induced ultraviolet emission is also expected for other trivalent rare-earth ions similar to Tm(3+). PMID:17167593

  19. The spread of excitation in neocortical columns visualized with infrared-darkfield videomicroscopy.

    PubMed

    Dodt, H U; D'Arcangelo, G; Pestel, E; Zieglgänsberger, W

    1996-07-01

    A combination of darkfield techniques and infrared videomicroscopy was used to measure the intrinsic optical signal (IOS) in slices of adult rat neocortex. The IOS, which reflects changes in light transmittance and scattering, provides a means of studying the spread of neuronal excitation and its modulation with high sensitivity and spatial resolution. The column-like IOS elicited by orthodromic stimulation is in accordance with models of neocortical circuitry. Blockade of synaptic transmission by the glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D-2-amino-5-phosphovaleric acid (D-APV) reduced the IOS. The GABAA agonist muscimol and the neuroactive steroid 5 alpha-tetrahydrodeoxy-corticosterone (5 alpha-THDOC) decreased the spread of excitation, whereas the GABAA antagonist bicuculline increased it. The present data suggest that the spatial spread of excitation in different neocortical layers is delimited by GABAergic inhibition mediated by the activation of GABAA receptors. PMID:8904754

  20. Charged-particle emission from dielectric materials initiated by a tunable picosecond mid-infrared laser

    Microsoft Academic Search

    David R. Ermer; Michael R. Papantonakis; Michelle Baltz-Knorr; Richard F. Haglund

    2000-01-01

    In the ultraviolet, visible and near-infrared, single and multiphoton electronic transitions can explain the production and emission of charged atoms, molecules and photoelectrons during laser ablation and desorption. However, the process of charge transfer and ionization during ablation of dielectrics in the mid-infrared is not well understood. Even though significant electronic excitation is unlikely, copious emission of charged particles, e.g.

  1. High-resolution multimodal clinical multiphoton tomography of skin

    Microsoft Academic Search

    Karsten König

    2011-01-01

    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

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

    PubMed Central

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

    2011-01-01

    We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu3+ emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles. PMID:21833362

  3. Multiphoton versus confocal high resolution z-sectioning of enhanced green fluorescent microtubules: increased multiphoton photobleaching within the focal plane can be compensated using a Pockels cell and dual widefield detectors.

    PubMed

    Drummond, D R; Carter, N; Cross, R A

    2002-05-01

    Multiphoton excitation was originally projected to improve live cell fluorescence imaging by minimizing photobleaching effects outside the focal plane, yet reports suggest that photobleaching within the focal plane is actually worse than with one photon excitation. We confirm that when imaging enhanced green fluorescent protein, photobleaching is indeed more acute within the multiphoton excitation volume, so that whilst fluorescence increases as predicted with the square of the excitation power, photobleaching rates increase with a higher order relationship. Crucially however, multiphoton excitation also affords unique opportunities for substantial improvements to fluorescence detection. By using a Pockels cell to minimize exposure of the specimen together with multiple nondescanned detectors we show quantitatively that for any particular bleach rate multiphoton excitation produces significantly more signal than one photon excitation confocal microscopy in high resolution Z-axis sectioning of thin samples. Both modifications are readily implemented on a commercial multiphoton microscope system. PMID:12000556

  4. 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.

  5. Multi-Photon Laser Scanning Microscopy Using an Acoustic Optical Deflector

    Microsoft Academic Search

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

    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

  6. 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.

  7. New multimodal multiphoton imaging and spectroscopy apparatus for dermatology

    NASA Astrophysics Data System (ADS)

    Yu, Yingqiu; Lee, Anthony; Wang, Hequn; Zhao, Jianhua; Tang, Shuo; Lui, Harvey; McLean, David I.; Zeng, Haishan

    2010-02-01

    We present the construction of a new multimodal, multiphoton spectroscopic and imaging instrument for in vivo patient use. Utilizing a tunable femtosecond laser, we are able to simultaneously acquire two-photon excited fluorescence, second harmonic generation, and confocal reflectance images at half video rate, while concurrently acquiring two-photon excited fluorescence and second harmonic generation spectra.

  8. An atomic jet in a heat pipe for multiphoton spectroscopy.

    PubMed

    Philip, G

    2007-11-01

    A conventional heat pipe is modified to operate as a novel atomic jet setup with unprecedented advantages for multiphoton spectroscopy of alkaline-earth atoms especially to study the effect of external electric field, controlled excitation of forbidden transitions and for the study of collisional broadening and shift of excited states, and time evolution of Rydberg atoms. PMID:18052459

  9. In vivo multiphoton tomography of inflammatory tissue and melanoma

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Dimitrow, Enrico; Kaatz, Martin; Fluhr, Joachim; Elsner, Peter; Kobow, Jens; Konig, Karsten

    2005-04-01

    Multiphoton optical tomography provides the capability of non-invasive optical sectioning of skin with high spatial and intracellular resolution as well as high NIR (near infrared) light penetration into pigmented skin areas. The imaging system DermaInspect based on femtosecond laser pulses was used to perform multiphoton optical tomography in clinical studies. Patients with abnormal pigmented tissues were imaged in vivo. After the multiphoton imaging procedure, biopsies were taken, imaged again and further processed with standard histological methods. We report on preliminary results. The visualization of pigmented cell clusters based on non-linear luminescence using the novel multiphoton device was possible. These clusters could be clearly distinguished from non-pigmented cells. Cancerous tissues showed significant differences in the cell structure of the epidermal layers. The system DermaInspect might become a high resolution diagnostic tool for melanoma diagnostics.

  10. Standoff detection of highly energetic materials using laser-induced thermal excitation of infrared emission.

    PubMed

    Galán-Freyle, Nataly J; Pacheco-Londoño, Leonardo C; Figueroa-Navedo, Amanda M; Hernandez-Rivera, Samuel P

    2015-05-01

    A laser-mediated methodology for standoff infrared detection of threat chemicals is described in this article. Laser-induced thermal emissions (LITE) from vibrationally excited residue of highly energetic material (HEM) deposited on substrates were detected remotely. Telescope-based Fourier transform infrared (FT-IR) spectroscopy measurements were carried out on substrates containing small amounts of HEM at surface concentrations of 5-200 ?g/cm(2). Target substrates of various thicknesses were heated remotely using a carbon dioxide laser, and their mid-infrared (mid-IR), thermally stimulated emission spectra were recorded after heating. The telescope was configured from reflective optical elements to minimize emission losses in the mid-IR frequencies. Spectral replicas were acquired at distances from 4 to 64 m using an FT-IR interferometer at 4 cm(-1) resolution. The laser power, laser exposure times, and acquisition time of the FT-IR interferometer were adjusted to improve the detection and identification of samples. The advantages of increasing the thermal emission were easily observed in the results. The signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration) as well as the laser power and laser exposure time. The limits of detection obtained for the HEM studied were 140-21 ?g/cm(2) at 4 m. Detection was achieved at 64 m for a surface concentration of 200 ?g/cm(2). PMID:25811843

  11. 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

  12. 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.

  13. 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.

  14. Multiphoton ionization/dissociation of osmium tetroxide

    NASA Astrophysics Data System (ADS)

    Ding, D.; Puretzky, A. A.; Compton, R. N.

    1993-01-01

    The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO4) have been investigated from measurements of the kinetic energies of product ions (Os+, Os2+, OsO+, O2+, O+) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os+ ionization channel, such as OsO4?OsO4-n+nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os+ ion signal suggests that one or more of the steps leading to Os+ ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow (<0.2 eV) electrons also supports this interpretation. Os2+ is shown to result primarily from REMPI of Os+.

  15. Ultrafast Excited-State Dynamics of Nanoscale Near-Infrared Emissive Polymersomes

    PubMed Central

    Duncan, Timothy V.; Ghoroghchian, P. Peter; Rubtsov, Igor V.; Hammer, Daniel A.; Therien, Michael J.

    2009-01-01

    Formed through cooperative self-assembly of amphiphilic diblock copolymers and electronically conjugated porphyrinic near-infrared (NIR) fluorophores (NIRFs), NIR-emissive polymersomes (50 nm to 50 ?m diameter polymer vesicles) define a family of organic-based, soft-matter structures that are ideally suited for deep-tissue optical imaging and sensitive diagnostic applications. Here, we describe magic angle and polarized pump–probe spectroscopic experiments that: (i) probe polymersome structure and NIRF organization and (ii) connect emitter structural properties and NIRF loading with vesicle emissive output at the nanoscale. Within polymersome membrane environments, long polymer chains constrain ethyne-bridged oligo(porphinato)zinc(II) based supermolecular fluorophore (PZnn) conformeric populations and disperse these PZnn species within the hydrophobic bilayer. Ultrafast excited-state transient absorption and anisotropy dynamical studies of NIR-emissive polymersomes, in which the PZnn fluorophore loading per nanoscale vesicle is varied between 0.1–10 mol %, enable the exploration of concentration-dependent mechanisms for nonradiative excited-state decay. These experiments correlate fluorophore structure with its gross spatial arrangement within specific nanodomains of these nanoparticles and reveal how compartmentalization of fluorophores within reduced effective dispersion volumes impacts bulk photophysical properties. As these factors play key roles in determining the energy transfer dynamics between dispersed fluorophores, this work underscores that strategies that modulate fluorophore and polymer structure to optimize dispersion volume in bilayered nanoscale vesicular environments will further enhance the emissive properties of these sensitive nanoscale probes. PMID:18611010

  16. Pure Rotational Spectra of HNCO in the Far Infrared: Three Excited Bending States

    NASA Astrophysics Data System (ADS)

    Niedenhoff, M.; Yamada, K. M. T.; Winnewisser, G.

    1996-04-01

    Pure rotational transitions of the quasilinear molecule HNCO in the excited bending states, v4= 1, v5= 1, and v6= 1, were measured with high resolution in the far infrared employing the Giessen Fourier transform spectrometer. Besides a-type transitions with high rotational quantum numbers, b-type transitions from Ka= 1 ? 0 up to Ka= 5 ? 4 could be identified for ? 4and ? 6and from Ka= 2 ? 1 up to Ka= 7 ? 6 for ? 5. Effective molecular parameters were determined using the linear molecule Hamiltonian to reproduce the measured line positions for each subband. Several forbidden transitions between the in-planebending vibrations ? 4and ? 5and the out-of-planebending vibration ? 6could be identified, which enabled us to determine precisely the relative positions of the vibrational energy levels. The strong a-type Coriolis interaction, which causes the forbidden transitions, have been analyzed with the help of a Padé-formulation to describe the Karotational structure of the bending excited states. The considerably weaker b-type Coriolis interaction, which shifts the effective rotational parameters, has also been discussed.

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

    PubMed

    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. PMID:26049429

  18. 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.

  19. Single Photon Infrared Emission Spectroscopy: A Study of IR Emission from UV Laser Excited PAHs between 3 and 15 m

    E-print Network

    Cohen, Ronald C.

    Single Photon Infrared Emission Spectroscopy: A Study of IR Emission from UV Laser Excited PAHs (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs PAHs. Lorentzian band shapes were convoluted with the monochromator- slit function in order

  20. 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

  1. A series of flexible design adaptations to the Nikon E-C1 and E-C2 confocal microscope systems for UV, multiphoton and FLIM imaging.

    PubMed

    Botchway, Stanley W; Scherer, Kathrin M; Hook, Steve; Stubbs, Christopher D; Weston, Eleanor; Bisby, Roger H; Parker, Anthony W

    2015-04-01

    Multiphoton microscopy is widely employed in the life sciences using extrinsic fluorescence of low- and high-molecular weight labels with excitation and emission spectra in the visible and near infrared regions. For imaging of intrinsic and extrinsic fluorophores with excitation spectra in the ultraviolet region, multiphoton excitation with one- or two-colour lasers avoids the need for ultraviolet-transmitting excitation optics and has advantages in terms of optical penetration in the sample and reduced phototoxicity. Excitation and detection of ultraviolet emission around 300 nm and below in a typical inverted confocal microscope is more difficult and requires the use of expensive quartz optics including the objective. In this technical note we describe the adaptation of a commercial confocal microscope (Nikon, Japan E-C1 or E-C2) for versatile use with Ti-sapphire and OPO laser sources and the addition of a second detection channel that enables detection of ultraviolet fluorescence and increases detection sensitivity in a typical fluorescence lifetime imaging microscopy experiment. Results from some experiments with this setup illustrate the resulting capabilities. PMID:25664385

  2. Optimizing Fluorescence Collection Efficiency in Multiphoton Microscopy

    NASA Astrophysics Data System (ADS)

    Zinter, Joseph P.

    Over the past 20 years multiphoton microscopy has established itself as the premier modality for high resolution (<1um) deep tissue in vivo fluorescence imaging. The dramatic improvements in imaging performance when compared to more conventional techniques result from the use of longer wavelength excitation light (˜700--1000 nm), enabling deeper tissue penetration, and the spatially and temporally localized generation of fluorescence inherent in two-photon excitation, which virtually eliminates out-of-focus fluorescence. Imaging depths of ˜500 mum are now considered common practice, however, as the technique continues to increase in popularity and utility significant efforts are being made to maximize imaging depth. These efforts can be compartmentalized into those aimed at increasing fluorescence excitation and those attempting to maximize fluorescence collection. Progress has been made in increasing fluorescence excitation efficiency, however these approaches require costly and complicated optical instrumentation, and are often deemed impractical. Efforts targeted at increasing fluorescence collection efficiency have been limited due to the complexity of describing the ensemble of scattered fluorescent photons emerging from a sample and propagating through a microscope objective and the subsequent fluorescence collection pathway of a multiphoton microscope. Since there is no analytic solution for these fluorescent photon distributions as a function of imaging depth in the relevant, non-diffusive multiphoton imaging range, numerical techniques are required. Here is presented the first computational model of fluorescence propagation through the complete fluorescence collection pathway of a multiphoton microscope. Monte Carlo simulations were used to model the propagation of fluorescence as a function of imaging depth in a scattering sample with physiologically accurate optical properties, and to determine the collected and transmitted fluorescent fraction through the Olympus 20X 0.95NA microscope objective, one of the highest performance and most commonly used objectives for multiphoton imaging. It was determined that the complex trajectories of scattered photons entering the microscope objective emerge from the objective back aperture with a large spatio-angular distribution of fluorescence, which varies significantly with imaging depth and scattering length. Accurate determination of this distribution provided the information necessary to model, design, and fabricate a maximally efficient post-objective fluorescence collection pathway. Simulations corroborated by data from experimental tissue phantoms demonstrate collection efficiency improvements of 50--90% over conventional, non-optimized collection geometries at imaging depths of 1000 mum. Furthermore, the collection efficiency of the optimized system was found to be nearly constant over the entire imaging range (0--1000 mum), and only weakly dependent on the scattering length of the sample. In vivo imaging performance was verified by imaging YFP+ layer V neurons in mouse cortex to a depth of 850 mum. Optimizing the fluorescence collection system in multiphoton microscopy results in large gains in fluorescence collection efficiency which translate into increased imaging depth, higher resolution, and a decrease in required excitation power, thereby reducing the potential for photodamage and generation of background fluorescence. Imaging performance was found to be comparable to that of the complex techniques aimed at increasing fluorescence excitation, but far simpler to implement and at a cost roughly two orders of magnitude less.

  3. 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.

  4. Robert Feulgen Prize Lecture. Laser tweezers and multiphoton microscopes in life sciences.

    PubMed

    König, K

    2000-08-01

    Near infrared (NIR) laser microscopy enables optical micromanipulation, piconewton force determination, and sensitive fluorescence studies by laser tweezers. Otherwise, fluorescence images with high spatial and temporal resolution of living cells and tissues can be obtained via non-resonant fluorophore excitation with multiphoton NIR laser scanning microscopes. Furthermore, NIR femtosecond laser pulses at TW/cm2 intensities can be used to realize non-invasive contact-free surgery of nanometer-sized structures within living cells and tissues. Applications of these novel versatile NIR laser-based tools for the determination of motility forces, coenzyme and chlorophyll imaging, three-dimensional multigene detection, non-invasive optical sectioning of tissues ("optical biopsy"), functional protein imaging, and nanosurgery of chromosomes are described. PMID:11052257

  5. Experimental Resonance Enhanced Multiphoton Ionization (REMPI) studies of small molecules

    NASA Technical Reports Server (NTRS)

    Dehmer, J. L.; Dehmer, P. M.; Pratt, S. T.; Ohalloran, M. A.; Tomkins, F. S.

    1987-01-01

    Resonance enhanced multiphoton ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of exciting opportunities for both basic and applied science. On the applied side, REMPI has great potential as an ultrasensitive, highly selective detector for trace, reactive, or transient species. On the basic side, REMPI affords an unprecedented means of exploring excited state physics and chemistry at the quantum-state-specific level. An overview of current studies of excited molecular states is given to illustrate the principles and prospects of REMPI.

  6. 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

  7. Photoelectron angular distributions from resonant multiphoton ionization of atomic carbona)

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, J. L.; Dehmer, P. M.

    1985-01-01

    Atomic carbon in both the 3P ground state and the 1D first excited state is prepared by UV multiphoton dissociation of carbon tetrachloride. Photoelectron angular distributions were obtained following two photon resonant, three photon ionization via the 3p 1S0 ? 1D2 transition using linear polarized light and via the 3p 3D2 ? 3P0 transition using both linear and circular polarized light. The results illustrate that resonant multiphoton ionization of atomic carbon must be discussed in terms of the complex atom, and not within a single electron framework.

  8. 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.

  9. Efficiency vs. multi-photon contribution test for quantum dots

    E-print Network

    Ana Predojevic; Miroslav Jezek; Tobias Huber; Harishankar Jayakumar; Thomas Kauten; Glenn S. Solomon; Radim Filip; Gregor Weihs

    2014-03-19

    The development of linear quantum computing within integrated circuits demands high quality semiconductor single photon sources. In particular, for a reliable single photon source it is not sufficient to have a low multi-photon component, but also to possess high efficiency. We investigate the photon statistics of the emission from a single quantum dot with a method that is able to sensitively detect the trade-off between the efficiency and the multi-photon contribution. Our measurements show, that the light emitted from the quantum dot when it is resonantly excited possess a very low multi-photon content. Additionally, we demonstrated, for the first time, the non-Gaussian nature of the quantum state emitted from a single quantum dot.

  10. THz and infrared excitation spectrum below the Jahn-Teller transition in Sr3Cr2O8

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Schmidt, Michael; Günther, Axel; Schaile, Sebastian; Pascher, Nikola; Mayr, Franz; Goncharov, Yurii; Krug von Nidda, Hans-Albrecht; Loidl, Alois; Quintero-Castro, Diana; Islam, A. T. M. N.; Lake, Bella; Deisenhofer, Joachim

    2012-02-01

    We report on optical excitations observed recently in Sr3Cr2O8 by THz and infrared spectroscopy. Low-energy excitations below 3 THz are detected by THz time domain spectroscopy. These excitations can be divided into two different classes according to the temperature-dependent properties. One is emergent right below the Jahn-Teller transition temperature, which is determined by specific heat measurement to occur at 285 K [1, 2]. The other appears only below 100 K, where the fluctuations are sufficiently suppressed, consistent with the temperature dependence of low-energy Raman modes [3]. Infrared transmission measurements reveal a broad crystal-field excitation, which can be associated with an electronic transition from E to T2 orbital states. [4pt] [1] Zhe Wang et al., Phys. Rev. B 83, 201102 (2011) [0pt] [2] D. L. Quintero-Castro et al., Phys. Rev. B 81, 014415 (2010) [0pt] [3] D. Wulferding et al., Phys. Rev. B 84, 064419 (2011)

  11. PHYSICAL REVIEW A 83, 013405 (2011) Precision calculation of above-threshold multiphoton ionization in intense short-wavelength laser

    E-print Network

    Chu, Shih-I

    2011-01-01

    ) to infrared radiations (1×105 nm). With the recent development of intense and ultrashort-wavelength free-electron lasers [32­34], the study of multiphoton * zyzhou@ku.edu sichu@ku.edu processes in the high

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

    PubMed

    Lumbreras, Vicente; Bas, Esperanza; Gupta, Chhavi; Rajguru, Suhrud M

    2014-09-15

    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 Ca(2+) imaging. Both types of neurons responded consistently with robust intracellular Ca(2+) ([Ca(2+)]i) transients that matched the low-frequency IR pulses applied (4 ms, 0.25-1 pps). Radiant exposures of ?637 mJ/cm(2) resulted in continual neuronal activation. Temperature or [Ca(2+)] variations in the media did not alter the IR-evoked transients, ruling out extracellular Ca(2+) involvement or primary mediation by thermal effects on the plasma membrane. While blockage of Na(+), K(+), and Ca(2+) plasma membrane channels did not alter the IR-evoked response, blocking of mitochondrial Ca(2+) cycling with CGP-37157 or ruthenium red reversibly inhibited the IR-evoked [Ca(2+)]i transients. Additionally, the magnitude of the IR-evoked transients was dependent on ryanodine and cyclopiazonic acid-dependent Ca(2+) 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

  13. In vivo multiphoton imaging of collagen remodeling after microablative fractional rejuvenation

    Microsoft Academic Search

    Riccardo Cicchi; Dimitrios Kapsokalyvas; Michela Troiano; Piero Campolmi; Cristiano Morini; Alessandro Cosci; Daniela Massi; Torello Lotti; Francesco S. Pavone

    2011-01-01

    The potential of multiphoton microscopy in providing in-vivo early diagnosis of skin lesions has already been demonstrated, while its capability in therapy follow-up has not been deeply explored so far. Two-photon excited fluorescence and second-harmonic generation microscopy were used in combination to follow-up collagen remodeling after laser micro-ablative rejuvenation. Treated regions of volunteers were imaged with multiphoton microscopy before and

  14. 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.

  15. Attosecond XUV absorption spectroscopy of doubly excited states in helium atoms dressed by a time-delayed femtosecond infrared laser

    NASA Astrophysics Data System (ADS)

    Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.

    2015-01-01

    In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrödinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.

  16. Mid-infrared laser-driven broadband water-window supercontinuum generation from pre-excited medium.

    PubMed

    Li, Yang; Hong, Weiyi; Zhang, Qingbin; Wang, Shaoyi; Lu, Peixiang

    2011-11-21

    We theoretically investigate the broadband water-window supercontinuum generation from pre-excited medium with a mid-infrared pulse. We find that the wavelength scaling of the harmonic yield from near-visible (0.8 ?m) to mid-infrared (1.8 ?m) in single-atom level is ?(-2.7). Using an intense phase-stabilized few-cycle 1.6 ?m laser pulse, a broadband water window supercontinuum with bandwidth of approximately 140 eV is obtained. We also investigate the macroscopic effects and find that large initial population of the excited state leads to the high-density of free electrons, which shift the carrier-envelop phase of the driving pulse and further diminish the water-window supercontinuum generation. The highly-ionized medium also results in poor temporal and spatial properties of the attosecond pulse. Instead, small initial population of the excited state can produce well phase-matched xuv supercontinuum in water-window region and an 100-as pulse with central wavelength of 2.8 nm and pulse energy of 0.15 nJ can be filtered out. PMID:22109465

  17. 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.

  18. Phase modulated multiphoton microscopy

    E-print Network

    Karki, Khadga Jung; Pullerits, Tonu

    2015-01-01

    We show that the modulation of the phases of the laser beams of ultra-short pulses leads to modulation of the two photon fluorescence intensity. The phase modulation technique when used in multi-photon microscopy can improve the signal to noise ratio. The technique can also be used in multiplexing the signals in the frequency domain in multi-focal raster scanning microscopy. As the technique avoids the use of array detectors as well as elaborate spatiotemporal multiplexing schemes it provides a convenient means to multi-focal scanning in axial direction. We show examples of such uses. Similar methodology can be used in other non-linear scanning microscopies, such as second or third harmonic generation microscopy.

  19. State selection by resonant multiphoton ionization: N + 2 A 2Pi u, v +

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.

    1984-02-01

    Three photon resonant, four photon ionization of N2 via the o3 1?u, v'=1, 2 levels is shown to produce?90% N+2 A 2?u, v+=1, 2, respectively. These results suggest that resonant multiphoton ionization through Rydberg states with electronically excited ion cores may be a powerful technique for the production of electronically excited, vibrationally state-selected ions.

  20. 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

  1. 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 +/).

  2. Infrared photodissociation spectroscopy of benzene trimer ions. Switching of the dimer ion core in vibrationally excited states

    NASA Astrophysics Data System (ADS)

    Inokuchi, Yoshiya; Ohashi, Kazuhiko; Nishi, Nobuyuki

    1997-11-01

    A vibrational spectrum of benzene trimer ion, (C 6H 6) 3+, was measured in the 2900-3100 cm -1 region by infrared photodissociation spectroscopy. An intense band at 2986 cm -1 was attributed to a C?H stretching vibration of the dimer ion core in (C 6H 6) 3+. The spectra of isotopically mixed benzene trimer ions with benzene- d6 molecules were also obtained. From the analysis of asymmetric band shape, a switching of the dimer ion core is proposed to occur in the vibrationally excited state prior to the vibrational predissociation.

  3. Combining multiphoton and CARS microscopy for skin imaging

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; Weinigel, M.; Lademann, J.; Sterry, W.; Latka, I.; Dietzek, B.; Popp, J.; König, K.

    2011-03-01

    We present combined coherent anti Stokes Raman scattering and two-photon excited fluorescence microscopy, for label-free in vitro and in vivo imaging of skin with both chemical discrimination and subcellular resolution. In particular, we show how CARS microscopy is utilized to image lipid-rich structures inside the skin, preparing for a combined multiphoton and CARS imaging modality for biomedical research and skin imaging. As a further potential application the detection of topically applied oil on the skin is presented.

  4. Excite

    NSDL National Science Digital Library

    Hot on the heels of AltaVista's Raging Search (see the May 5, 2000 Scout Report) comes another returned and (somewhat) slimmed-down search engine that focuses on relevant results. Like Raging Search, Excite's new Precision Search uses Google-style link analysis technology ("Deep Analysis") to help identify the most useful sites. Test queries produced consistently relevant results among the top few returns, though an indication of the number of total returns would be helpful, with two banner ads and (in some but not all cases) a Quick Results box on the left that could be quite handy for consumer-related searching. For instance, a search for "Plymouth" yielded links to research and comparisons, blue book values, financing, and service and repair information in the Quick Results box. I was also pleased to see that clicking on one of the other search categories (category, news, photo, audio/video) instantly produces returns for the original query, though the photo databases available seem somewhat limited compared to, say, AltaVista. While users searching for "official" sites will still do best at Google, those who also search for additional resources such as news, photos, and audio/video content may wish to give Excite Precision a run-through.

  5. Ultrafast, large-field multiphoton microscopy based on an acousto-optic deflector and a spatial light modulator

    PubMed Central

    Shao, Yonghong; Qin, Wan; Liu, Honghai; Qu, Junle; Peng, Xiang; Niu, Hanben; Gao, Bruce Z.

    2013-01-01

    We present an ultrafast, large-field multiphoton excitation fluorescence microscope with high lateral and axial resolutions based on a two-dimensional (2-D) acousto-optical deflector (AOD) scanner and spatial light modulator (SLM). When a phase-only SLM is used to shape the near-infrared light from a mode-locked titanium:sapphire laser into a multifocus array including the 0-order beam, a 136 ?m × 136 ?m field of view is achieved with a 60× objective using a 2-D AOD scanner without any mechanical scan element. The two-photon fluorescence image of a neuronal network that was obtained using this system demonstrates that our microscopy permits observation of dynamic biological events in a large field with high-temporal and -spatial resolution. PMID:22743445

  6. Ultrafast, large-field multiphoton microscopy based on an acousto-optic deflector and a spatial light modulator.

    PubMed

    Shao, Yonghong; Qin, Wan; Liu, Honghai; Qu, Junle; Peng, Xiang; Niu, Hanben; Gao, Bruce Z

    2012-07-01

    We present an ultrafast, large-field multiphoton excitation fluorescence microscope with high lateral and axial resolutions based on a two-dimensional (2-D) acousto-optical deflector (AOD) scanner and spatial light modulator (SLM). When a phase-only SLM is used to shape the near-infrared light from a mode-locked titanium:sapphire laser into a multifocus array including the 0-order beam, a 136 ?m × 136 ?m field of view is achieved with a 60× objective using a 2-D AOD scanner without any mechanical scan element. The two-photon fluorescence image of a neuronal network that was obtained using this system demonstrates that our microscopy permits observation of dynamic biological events in a large field with high-temporal and -spatial resolution. PMID:22743445

  7. 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.

  8. Invited Review Article: Imaging techniques for harmonic and multiphoton absorption fluorescence microscopy

    PubMed Central

    Carriles, Ramón; Schafer, Dawn N.; Sheetz, Kraig E.; Field, Jeffrey J.; Cisek, Richard; Barzda, Virginijus; Sylvester, Anne W.; Squier, Jeffrey A.

    2009-01-01

    We review the current state of multiphoton microscopy. In particular, the requirements and limitations associated with high-speed multiphoton imaging are considered. A description of the different scanning technologies such as line scan, multifoci approaches, multidepth microscopy, and novel detection techniques is given. The main nonlinear optical contrast mechanisms employed in microscopy are reviewed, namely, multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation. Techniques for optimizing these nonlinear mechanisms through a careful measurement of the spatial and temporal characteristics of the focal volume are discussed, and a brief summary of photobleaching effects is provided. Finally, we consider three new applications of multiphoton microscopy: nonlinear imaging in microfluidics as applied to chemical analysis and the use of two-photon absorption and self-phase modulation as contrast mechanisms applied to imaging problems in the medical sciences. PMID:19725639

  9. 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.

  10. 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.

  11. Infrared-active excitations related to Ho3+ ligand-field splitting

    E-print Network

    Sirenko, Andrei

    ; published 6 November 2008 Linearly polarized spectra of far-infrared IR transmission in HoMn2O5 multiferroic and ferroelec- tric orderings has recently motivated extensive studies of rare-earth multiferroic manganites RMn and for possible device applications due to the in- triguing phase diagram and magnetic-field-induced spontane- ous

  12. 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.

  13. Reduction of excitation by interleukin-1 beta in rat neocortical slices visualized using infrared-darkfield videomicroscopy.

    PubMed

    D'Arcangelo, G; Dodt, H U; Zieglgänsberger, W

    1997-05-27

    The cytokine interleukin-1 beta (IL-1 beta) is thought to be critically involved in the neuroendocrine and behavioral changes which occur in response to systemic infection. In the present study, we have employed the novel technique of infrared-darkfield videomicroscopy to examine the effect of IL-1 beta on the intrinsic optical signal (IOS), an indicator of the spread of neuronal excitation and synaptic transmission in the mammalian central nervous system. Low doses of IL-1 beta delivered exogenously to rat neocortical slices produced a reduction of the area of the column-like IOS evoked by orthodromic stimulation. The effect of IL-1 beta was reversible on washout and not mimicked by heat-inactivated IL-1 beta. These results suggest a possible modulatory role of IL-1 beta on synaptic transmission in the rat neocortex which is probably mediated through an activation of GABAA receptors. PMID:9223105

  14. Near-infrared-excitation resonance Raman spectra of the primary electron donor in photosynthetic reaction centers from Rhodobacter sphaeroides

    SciTech Connect

    Donohoe, R.J.; Dyer, R.B.; Swanson, B.I. (Los Alamos National Lab., NM (USA)); Violette, C.A.; Frank, H.A. (Univ. of Connecticut, Storrs (USA)); Bocian, D.F. (Carnegie Mellon Univ., Pittsburgh, PA (USA))

    1990-08-29

    The x-ray crystal structures of bacterial photosynthetic reaction centers (RCs) serve as bench marks for establishing a detailed description of the light-induced electron-transfer process. Much recent work has focused on the characterization of the electronic properties of the primary electron donor state (P*), which is an excited state of the special pair dimer of bacteriochlorophyll (BChl) molecules in RCs. Thus far, most studies of P* have relied on optical spectroscopic techniques. No resonance Raman (RR) experiments have been reported that directly probe this state. The authors report the results of preliminary, low-frequency RR studies that probe the photophysically important, near-infrared absorption band of the primary electron donor in RCs from Rhodobacter sphaeroides wild-type strain 2.4.1.

  15. Two-photon fluorescence excitation in continuous-wave infrared optical tweezers

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Sonek, G. J.; Berns, M. W.; Konig, K.; Tromberg, B. J.

    1995-11-01

    We report the observation of two-photon fluorescence excitation in a continuous-wave (cw) single-beam gradient force optical trap and demonstrate its use as an in situ probe to study the physiological state of an optically confined sample. In particular, a cw Nd:YAG (1064-nm) laser is used simultaneously to confine, and excite visible fluorescence from submicrometer regions of, cell specimens. Two-photon fluorescence emission spectra are presented for motile human sperm cells and immotile Chinese hamster ovary cells that have been labeled with nucleic acid (Propidium Iodide) and pH-sensitive (Snarf) fluorescent probes. The resulting spectra are correlated to light-induced changes in the physiological state experienced by the trapped cells. This spectral technique should prove extremely useful for monitoring cellular activity and the effects of confinement by optical tweezers.

  16. Stochastic scanning multiphoton multifocal microscopy

    E-print Network

    Scherer, Norbert F.

    -2928 (2005). 2. W. Denk, J. H. Strickler, and W. W. Webb, "Two-photon laser scanning fluorescence microscopy, 2002). 5. M. A. Digman, C. M. Brown, P. Sengupta, P. W. Wiseman, A. R. Horwitz, and E. Gratton-1327 (2005). 6. J. Bewersdorf, R. Pick, and S. W. Hell, "Multifocal multiphoton microscopy," Opt. Lett. 23

  17. Development of near-infrared 35 fs laser microscope and its application to the detection of three- and four-photon fluorescence of organic microcrystals.

    PubMed

    Matsuda, Hirohisa; Fujimoto, Yousuke; Ito, Syoji; Nagasawa, Yutaka; Miyasaka, Hiroshi; Asahi, Tsuyoshi; Masuhara, Hiroshi

    2006-01-26

    Femtosecond near-infrared laser microscope was developed with a home-built cavity-dumped chromium:forsterite laser as a light source centered at 1.26 microm. Optimization of the pulse duration achieved 35 fs fwhm at the sample position of the microscope after passing through a 100x objective. This system was applied to the detection of multiphoton fluorescence of some organic microcrystals. Excitation intensity dependence and the interferometric autocorrelation detection of the fluorescence clearly demonstrated that simultaneous three- and four-photon absorption processes are responsible for the production of the excited state for perylene and anthracene microcrystals, respectively. The spatial resolution along the optical axis and its dependence on the order of the multiphoton process were also discussed. PMID:16471646

  18. Optical and Near Infrared Study of the Cepheus E outflow, a very low excitation object

    E-print Network

    S. Ayala; A. Noriega-Crespo; P. M. Garnavich; S. Curiel; A. C. Raga; K. H. Bohm; J. Raymond

    2000-04-20

    We present images and spectra of the Cepheus E (Cep E) region at both optical and infrared wavelengths. Only the brightest region of the southern lobe of the Cep E outflow reveals optical emission, suggesting that the extinction close to the outflow source plays an important r\\^ole in the observed difference between the optical and IR morphologies. Cep E is a unique object since it provides a link between the spectroscopic properties of the optical Herbig-Haro (HH) objects and those of deeply embedded outflows.

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

    SciTech Connect

    Ishii, Masashi, E-mail: ISHII.Masashi@nims.go.jp [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce [Photon Science Institute and School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Knights, Andrew P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Gwilliam, Russell M. [Advanced Technology Institute, University of Surrey, Guildford GU2 5XH (United Kingdom)

    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.

  20. Raman scattering and plasmonic photocatalysis of single particles of NaYF4:Yb,Er@Ag under near-infrared laser excitation.

    PubMed

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

    2014-11-21

    This study has investigated the plasmonic photocatalytic ability of silver nanoparticles (Ag NPs) and the significantly improved Raman achieved by decorating them on a single NaYF4:Yb,Er upconversion (UC) microcrystal under near-infrared excitation. This points to new applications for UC-noble metal composites and promises a novel method for constructing SERS-active nanostructures. PMID:25267978

  1. A Near-Infrared Transient Absorption Study of the Excited-State Dynamics of the Carotenoid Spirilloxanthin in Solution and in the LH1 Complex of Rhodospirillum rubrum

    E-print Network

    van Stokkum, Ivo

    A Near-Infrared Transient Absorption Study of the Excited-State Dynamics of the Carotenoid-state properties of carotenoids are largely deter- mined by their polyene backbone and play an important role been included in the description of this function of carotenoids: the S2 (1Bu + in C2h symmetry group

  2. Resonantly enhanced third-harmonic generation and multiphoton ionization in cesium vapor

    Microsoft Academic Search

    S. M. Hamadani; J. A. D. Stockdale; R. N. Compton

    1986-01-01

    Simultaneous third-harmonic generation and multiphoton ionization are investigated in cesium. Very large infrared to blue conversion efficiencies (approx.1%) are observed near the two-photon allowed 6D states and three-photon allowed 7P states. 1 ref., 3 figs.

  3. 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.

  4. Infrared two-photon-excited visible lasing from a DNA-surfactant-chromophore complex

    NASA Astrophysics Data System (ADS)

    He, Guang S.; Zheng, Qingdong; Prasad, Paras N.; Grote, James G.; Hopkins, Frank K.

    2006-02-01

    Infrared two-photon-pumped and cavity-enhanced frequency upconversion lasing has been achieved in a novel DNA-surfactant-chromophore complex (DSCC) gel system, which is a new step toward producing a biological laser. Once the focused intensity of the 150 fs and ˜775 nm pump laser beam is higher than a certain threshold level, highly directional stimulated emission at ˜582 nm wavelength can be observed from a 1 cm long DSCC complex gel cell. With cavity feedback provided by the two optical windows, the pump threshold can be further reduced, the highly directional output lasing can be greatly enhanced, and the output spectral linewidth can be reduced to less than 1/5 of the spontaneous fluorescence spectral bandwidth.

  5. Infrared two-photon-excited visible lasing from a DNA-surfactant-chromophore complex.

    PubMed

    He, Guang S; Zheng, Qingdong; Prasad, Paras N; Grote, James G; Hopkins, Frank K

    2006-02-01

    Infrared two-photon-pumped and cavity-enhanced frequency upconversion lasing has been achieved in a novel DNA-surfactant-chromophore complex (DSCC) gel system, which is a new step toward producing a biological laser. Once the focused intensity of the 150 fs and approximately 775 nm pump laser beam is higher than a certain threshold level, highly directional stimulated emission at approximately 582 nm wavelength can be observed from a 1 cm long DSCC complex gel cell. With cavity feedback provided by the two optical windows, the pump threshold can be further reduced, the highly directional output lasing can be greatly enhanced, and the output spectral linewidth can be reduced to less than 1/5 of the spontaneous fluorescence spectral bandwidth. PMID:16480208

  6. Multiphoton Magnetooptical Trap

    SciTech Connect

    Wu Saijun; Plisson, Thomas; Brown, Roger C.; Phillips, William D.; Porto, J. V. [Joint Quantum Institute, NIST and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    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.

  7. Infrared optical excitations in La{sub 2}NiO{sub 4}

    SciTech Connect

    Perkins, J.D.; Kleinberg, D.S.; Kastner, M.A.; Birgeneau, R.J. [Center for Material Science and Engineering and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Center for Material Science and Engineering and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Endoh, Y.; Yamada, K.; Hosoya, S. [Department of Physics, Tohoku University, Aramaki Aoba, Aoba-ku, Sendai 980 (Japan)] [Department of Physics, Tohoku University, Aramaki Aoba, Aoba-ku, Sendai 980 (Japan)

    1995-10-01

    Measurements are reported of the transmission of single crystals of La{sub 2}NiO{sub 4} containing no excess oxygen. Several weak absorption bands are observed in the range 0.15--2 eV arising from magnetic and crystal-field excitations. The lowest-energy band, at 0.25 eV, is quantitatively described by a recent theory for phonon-assisted creation of a virtual bound state of two magnons. However, unlike La{sub 2}CuO{sub 4}, no higher-energy sidebands are detected, suggesting that the broad, structured absorption seen clearly in La{sub 2}CuO{sub 4} between {similar_to}0.4 and 1 eV results from sidebands to crystal-field excitons as previously proposed.

  8. 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.

  9. Temporal coherence in multiphoton absorption. Far off-resonance intermediate states

    Microsoft Academic Search

    P. W. Milonni; J. H. Eberly

    1978-01-01

    We develop a consistent formalism for the treatment of temporal atomic or molecular coherence in multiphoton absorption. The formalism is fully quantum mechanical under the assumption that the exciting laser fields are well described by coherent states. We make use of the language and methodology of resonance physics to the extent possible, but deliberately avoid the rotating-wave approximation, and do

  10. Infrared and ultraviolet laser spectroscopy of jet-cooled substituted salicylic acids; substitution effects on the excited state intramolecular proton transfer in salicylic acid

    NASA Astrophysics Data System (ADS)

    Abd El-Hakam Abou El-Nasr, E.; Fujii, A.; Ebata, T.; Mikami, N.

    Substitution effects on the excited state intramolecular proton transfer (ESIPT) in the salicylic acid (SA) frame were studied by electronic and infrared spectroscopy of jet-cooled 5-methoxylsalicylic acid (5-MeOSA), 5-methylsalicylic acid (5-MeSA), 5-fluorosalicylic acid (5-FSA), 6-fluorosalicylic acid (6-FSA), and methyl salicylate (MS). Infrared spectra were measured in the 3 µm region for both the electronic ground (S0) and first excited (S1) states. The electronic excitation/emission spectra of 5-MeSA and 6-FSA showed the typical spectral features of ESIPT, which have been found in the spectra of SA. On the other hand, 5-MeOSA and 5-FSA exhibit a mirror-image relation between their excitation and emission spectra, which has been regarded as a result of the suppression of ESIPT. Despite such a remarkable difference among the electronic spectra, IR spectroscopy shows that a drastic change of the phenolic OH stretching vibration does occur upon electronic excitation of all substituted SAs, that is, the phenolic OH band of all the SAs disappears from the 3 µm region, indicating a large elongation of the phenolic O-H bond (over 0.1 Å) in S1. This result means that the intramolecular hydrogen bond strength is remarkably enhanced by electronic excitation in all the substituted SAs. Substitution effects on ESIPT in dimers are also discussed.

  11. Spread of cochlear excitation during stimulation with pulsed infrared radiation: Inferior colliculus measurements

    PubMed Central

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

    2012-01-01

    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 ?m-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 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 spatial tuning curves indicated that the spread of activation evoked by optical stimuli is comparable to that produced by acoustic pips. PMID:21828906

  12. 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.

  13. PROBING THE EXCITATION OF EXTREME STARBURSTS: HIGH-RESOLUTION MID-INFRARED SPECTROSCOPY OF BLUE COMPACT DWARFS

    SciTech Connect

    Hao Lei [University of Texas at Austin, McDonald Observatory, 1 University Station, C1402, Austin, TX 78712-0259 (United States); Wu Yanling [Caltech, Infrared Processing and Analysis Center, MC 314-6, Pasadena, CA 91125 (United States); Charmandaris, V. [University of Crete, Department of Physics, P.O. Box 2208, GR-71003, Heraklion (Greece); Spoon, H. W. W.; Bernard-Salas, J.; Lebouteiller, V.; Houck, J. R. [Cornell University, Astronomy Department, Ithaca, NY 14853-6801 (United States); Devost, D., E-mail: haol@astro.as.utexas.ed [CFHT: Canada France Hawaii Telescope, Kamuela, HI, 96743 (United States)

    2009-10-20

    We present an analysis of the mid-infrared emission lines for a sample of 12 low-metallicity blue compact dwarf (BCD) galaxies based on high-resolution observations obtained with Infrared Spectrograph on board the Spitzer Space Telescope. We compare our sample with a local sample of typical starburst galaxies and active galactic nuclei (AGNs) to study the ionization field of starbursts over a broad range of physical parameters and examine its difference from the one produced by the AGN. The high-ionization line [O IV]25.89 mum is detected in most of the BCDs, starbursts, and AGNs in our sample. We propose a diagnostic diagram of the line ratios [O IV]25.89 mum/[S III]33.48 mum as a function of [Ne III]15.56 mum/[Ne II]12.81 mum which can be useful in identifying the principal excitation mechanism in a galaxy. Galaxies in this diagram split naturally into two branches. Classic AGNs as well as starburst galaxies with an AGN component populate the upper branch, with stronger AGNs displaying higher [Ne III]/[Ne II] ratios. BCDs and pure starbursts are located in the lower branch. We find that overall the placement of galaxies on this diagram correlates well with their corresponding locations in the log([N II]/Halpha) versus log([O III]/Hbeta) diagnostic diagram, which has been widely used in the optical. The two diagrams provide consistent classifications of the excitation mechanism in a galaxy. On the other hand, the diagram of [Ne III]15.56 mum/[Ne II]12.81 mum versus [S IV]10.51 mum/[S III]18.71 mum is not as efficient in separating AGNs from BCDs and pure starbursts. Our analysis demonstrates that BCDs in general do display higher [Ne III]/[Ne II] and [S IV]/[S III] line ratios than starbursts, with some reaching values even higher than those found at the centers of AGNs. Despite their hard radiation field though, no [Ne V]14.32 mum emission has been detected in the BCDs of our sample.

  14. Warm Molecular Gas in M51: Mapping the Excitation Temperature and Mass of H_2 with the Spitzer Infrared Spectrograph

    E-print Network

    G. Brunner; K. Sheth; L. Armus; M. Wolfire; S. Vogel; E. Schinnerer; G. Helou; R. Dufour; J. Smith; D. Dale

    2007-11-30

    We have mapped the warm molecular gas traced by the H_2 S(0) - H_2 S(5) pure rotational mid-infrared emission lines over a radial strip across the nucleus and disk of M51 (NGC 5194) using the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The six H_2 lines have markedly different emission distributions. We obtained the H_2 temperature and surface density distributions by assuming a two temperature model: a warm (T = 100 - 300 K) phase traced by the low J (S(0) - S(2)) lines and a hot phase (T = 400 - 1000 K) traced by the high J (S(2) - S(5)) lines. The lowest molecular gas temperatures are found within the spiral arms (T ~ 155 K), while the highest temperatures are found in the inter-arm regions (T > 700 K). The warm gas surface density reaches a maximum of 11 M_sun/pc^2 in the northwestern spiral arm, whereas the hot gas surface density peaks at 0.24 M_sun/pc^2 at the nucleus. The spatial offset between the peaks in the warm and hot phases and the differences in the distributions of the H_2 line emission suggest that the warm phase is mostly produced by UV photons in star forming regions while the hot phase is mostly produced by shocks or X-rays associated with nuclear activity. The warm H_2 is found in the dust lanes of M51, spatially offset from the brightest HII regions. The warm H_2 is generally spatially coincident with the cold molecular gas traced by CO (J = 1 - 0) emission, consistent with excitation of the warm phase in dense photodissociation regions (PDRs). In contrast, the hot H_2 is most prominent in the nuclear region. Here, over a 0.5 kpc radius around the nucleus of M51, the hot H_2 coincides with [O IV](25.89 micron) and X-ray emission indicating that shocks and/or X-rays are responsible for exciting this phase.

  15. Differential Multiphoton Laser Scanning Microscopy

    Microsoft Academic Search

    Jeffrey J. Field; Kraig E. Sheetz; Eric V. Chandler; Erich E. Hoover; Michael D. Young; Shi-you Ding; Anne W. Sylvester; David Kleinfeld; Jeff A. Squier

    2012-01-01

    Multifocal multiphoton laser scanning microscopy (mfMPLSM) in the biological and medical sciences has the potential to become a ubiquitous tool for obtaining high-resolution images at video rates. While current implementations of mfMPLSM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on

  16. Model atom for multiphoton physics

    Microsoft Academic Search

    Q. Su; J. H. Eberly

    1991-01-01

    We describe in detail some properties of a one-dimensional model atom that has been used for the study of multiphoton processes. We discuss static properties of the atom such as its energy eigenvalues, dipole moment matrix elements, and dipole sum rule, and also some aspects of its time-dependent response to a weak laser field, including second-order level shifts, and exact

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

    PubMed

    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. PMID:23797897

  18. 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.

  19. Differentiating the two main histologic categories of fibroadenoma tissue from normal breast tissue by using multiphoton microscopy.

    PubMed

    Nie, Y T; Wu, Y; Fu, F M; Lian, Y E; Zhuo, S M; Wang, C; Chen, J X

    2015-04-01

    Multiphoton microscopy has become a novel biological imaging technique that allows cellular and subcellular microstructure imaging based on two-photon excited fluorescence and second harmonic generation. In this work, we used multiphoton microscopy to obtain the high-contrast images of human normal breast tissue and two main histologic types of fibroadenoma (intracanalicular, pericanalicular). Moreover, quantitative image analysis was performed to characterize the changes of collagen morphology (collagen content, collagen orientation). The results show that multiphoton microscopy combined with quantitative method has the ability to identify the characteristics of fibroadenoma including changes of the duct architecture and collagen morphology in stroma. With the advancement of multiphoton microscopy, we believe that the technique has great potential to be a real-time histopathological diagnostic tool for intraoperative detection of fibroadenoma in the future. PMID:25644822

  20. Multiphoton Quantum Optics and Quantum State Engineering

    Microsoft Academic Search

    Fabio Dell' Anno; Silvio De Siena; Fabrizio Illuminati

    We present a review of theoretical and experimental aspects of multiphoton quan- tum 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 pro- cesses, and interferometry. A single review cannot account

  1. Multiphoton quantum optics and quantum state engineering

    Microsoft Academic Search

    Fabio Dell’Anno; Silvio De Siena; Fabrizio Illuminati

    2006-01-01

    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

  2. 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.

  3. Rotation–torsion analysis of the Si2H6 infrared fundamental ?9, perturbed by excited torsional levels of the vibrational ground state

    Microsoft Academic Search

    F. Lattanzi; C. Di Lauro; V.-M. Horneman

    2004-01-01

    The lowest infrared active perpendicular fundamental ?9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430?cm, at the spectral resolution of 0.0012?cm. The rotation–torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3?4 and 4?4 in the high barrier limit.

  4. Rotation-torsion analysis of the Si2H6 infrared fundamental nu, perturbed by excited torsional levels of the vibrational ground state

    Microsoft Academic Search

    F. Lattanzi; C. di Lauro; V.-M. Horneman

    2004-01-01

    The lowest infrared active perpendicular fundamental nu9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430 cm-1, at the spectral resolution of 0.0012 cm-1. The rotation-torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3nu4 and 4nu4 in the high

  5. Photocurrent generation of a porphyrin self-assembly monolayer on a gold film electrode by surface plasmon excitation using near-infrared light

    Microsoft Academic Search

    Akito Ishida; Tetsuro Majima

    2000-01-01

    Photocurrent was generated by irradiation of a porphyrin self-assembly monolayer on a gold film electrode with near-infrared (IR) as well as visible light under the surface plasmon (SP) resonance conditions. The action spectrum by the SP excitation demonstrated existence of discrete active bands in the near-IR region together with the Soret and Q-bands. These bands may be attributable to the

  6. The multiphoton ionization of uranium hexafluoride

    SciTech Connect

    Armstrong, D.P. (Oak Ridge K-25 Site, TN (United States). 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.

  7. Multiphoton Microscopy for Ophthalmic Imaging

    PubMed Central

    Gibson, Emily A.; Masihzadeh, Omid; Lei, Tim C.; Ammar, David A.; Kahook, Malik Y.

    2011-01-01

    We review multiphoton microscopy (MPM) including two-photon autofluorescence (2PAF), second harmonic generation (SHG), third harmonic generation (THG), fluorescence lifetime (FLIM), and coherent anti-Stokes Raman Scattering (CARS) with relevance to clinical applications in ophthalmology. The different imaging modalities are discussed highlighting the particular strength that each has for functional tissue imaging. MPM is compared with current clinical ophthalmological imaging techniques such as reflectance confocal microscopy, optical coherence tomography, and fluorescence imaging. In addition, we discuss the future prospects for MPM in disease detection and clinical monitoring of disease progression, understanding fundamental disease mechanisms, and real-time monitoring of drug delivery. PMID:21274261

  8. 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

    2015-07-13

    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

  9. Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique

    PubMed Central

    Tang, Jianyong; Germain, Ronald N.; Cui, Meng

    2012-01-01

    Biological tissues are rarely transparent, presenting major challenges for deep tissue optical microscopy. The achievable imaging depth is fundamentally limited by wavefront distortions caused by aberration and random scattering. Here, we report an iterative wavefront compensation technique that takes advantage of the nonlinearity of multiphoton signals to determine and compensate for these distortions and to focus light inside deep tissues. Different from conventional adaptive optics methods, this technique can rapidly measure highly complicated wavefront distortions encountered in deep tissue imaging and provide compensations for not only aberration but random scattering. The technique is tested with a variety of highly heterogeneous biological samples including mouse brain tissue, skull, and lymph nodes. We show that high quality three-dimensional imaging can be realized at depths beyond the reach of conventional multiphoton microscopy and adaptive optics methods, albeit over restricted distances for a given correction. Moreover, the required laser excitation power can be greatly reduced in deep tissues, deviating from the power requirement of ballistic light excitation and thus significantly reducing photo damage to the biological tissue. PMID:22586078

  10. High-resolution spectroscopy and dynamics of multiphoton processes in atoms and molecules

    NASA Astrophysics Data System (ADS)

    Dehmer, P. M.; Dehmer, J. L.

    1985-06-01

    This report summarizes research on resonantly enhanced multiphoton absorption dissociation, and ionization processes in atoms and molecules. Multiphoton processes are studied using from one to three independently tunable visible and/or UV laser beams in order to establish both the underlying physics and the high degree of selectivity of multiphoton processes. Measurements are made to probe both the formation of excited molecular states and the subsequent behavior of excited states either in the presence or in the abscence of further intense laser radiation. Detection methods include laser-induced fluorescence, ion mass analysis, and electron energy analysis. During the current reporting period, we have studied resonant multiphoton ionization processes for the molecules N2, CO, O2, NO, NeXe, ArXe, KrXe, and Xe2 and for the atoms C, I, and S using both mass spectrometry and photoelectron spectroscopy to analyze the products of the ionizations. In addition, we are developing three new instruments that will provide significantly enhanced resolution, collection efficiency, and versatility in both the ion mass and the electron kinetic energy detection channels.

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. New developments in multimodal clinical multiphoton tomography

    Microsoft Academic Search

    Karsten König

    2011-01-01

    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

  16. Kinetic studies following state-selective laser excitation

    SciTech Connect

    Keto, J.W.

    1992-01-01

    We have made measurements of state-to-state deactivation cross sections and radiative lifetimes for Xe*(6p,6p{prime},7p) and Kr*(5p) states in xenon and krypton buffer gases. These results are relevant to kinetic models and both excimer lasers and the infrared xenon laser; and they are a significant improvement in the precision of the known radiative lifetimes. This type of experiment can now be compared with recent calculations of state-to-state collisional relaxation in rare-gases by Hickman, Huestis, and Saxon. We have also made significant progress in the study of the electronic spectra of small molecules of the rare gases. Spectra have been obtained for Xe{sub 2}, Xe{sub 3}, Xe{sub 4}, and larger clusters. As guidance for the larger clusters of the rare gases we have obtained the first multiphoton spectra for excitons in condensed xenon. In collaboration with research on the multiphoton spectra of the rare gases, we have continued experiments using synchrotron radiation in collaboration with the University of Hamburg. In experiments there we have observed excitation and fluorescence spectra for single xenon atoms at the surface, within the second layer, and within the bulk of large argon clusters.

  17. 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.

  18. 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.

  19. Picosecond 266-nm multiphoton laser photolysis studies on liquid alkane solution of aromatic hydrocarbons: Ultrafast solute triplet formation

    Microsoft Academic Search

    Hiroshi. Miyasaka; Hiroshi. Masuhara; Noboru. Mataga

    1990-01-01

    Triplet formation of aromatic hydrocarbon solute in aliphatic hydrocarbon solution in the picosecond to a few nanosecond time region induced by multiphoton excitation with 266-nm picosecond laser pulse is demonstrated. Mechanisms of the rapid triplet state formation, especially the contribution of the ionized state of solvent molecule to it, are discussed by comparing the results of picosecond laser photolysis studies

  20. 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

  1. Nanoparticle-assisted-multiphoton microscopy for in vivo brain imaging of mice

    NASA Astrophysics Data System (ADS)

    Qian, Jun

    2015-03-01

    Neuro/brain study has attracted much attention during past few years, and many optical methods have been utilized in order to obtain accurate and complete neural information inside the brain. Relying on simultaneous absorption of two or more near-infrared photons by a fluorophore, multiphoton microscopy can achieve deep tissue penetration and efficient light detection noninvasively, which makes it very suitable for thick-tissue and in vivo bioimaging. Nanoparticles possess many unique optical and chemical properties, such as anti-photobleaching, large multiphoton absorption cross-section, and high stability in biological environment, which facilitates their applications in long-term multiphoton microscopy as contrast agents. In this paper, we will introduce several typical nanoparticles (e.g. organic dye doped polymer nanoparticles and gold nanorods) with high multiphoton fluorescence efficiency. We further applied them in two- and three-photon in vivo functional brain imaging of mice, such as brain-microglia imaging, 3D architecture reconstruction of brain blood vessel, and blood velocity measurement.

  2. Multiphoton-induced X-ray emission and amplification from clusters

    Microsoft Academic Search

    A. McPherson; T. S. Luk; B. D. Thompson; K. Boyer; C. K. Rhodes

    1993-01-01

    The development of a unified picture of short-pulse high-intensity multiphoton processes, embracing atoms, molecules, and solids, appears possible through the study of clusters. Of particular significance are possible intra-cluster processes that can influence the mechanism of ionization and lead to the production of inner-shell vacancies. Inner-shell excitation leading to prompt X-ray emission is specifically considered and the treatment leads to

  3. Multiphoton microscopy as a diagnostic imaging modality for lung cancer

    NASA Astrophysics Data System (ADS)

    Pavlova, Ina; Hume, Kelly R.; Yazinski, Stephanie A.; Peters, Rachel M.; Weiss, Robert S.; Webb, Watt W.

    2010-02-01

    Lung cancer is the leading killer among all cancers for both men and women in the US, and is associated with one of the lowest 5-year survival rates. Current diagnostic techniques, such as histopathological assessment of tissue obtained by computed tomography guided biopsies, have limited accuracy, especially for small lesions. Early diagnosis of lung cancer can be improved by introducing a real-time, optical guidance method based on the in vivo application of multiphoton microscopy (MPM). In particular, we hypothesize that MPM imaging of living lung tissue based on twophoton excited intrinsic fluorescence and second harmonic generation can provide sufficient morphologic and spectroscopic information to distinguish between normal and diseased lung tissue. Here, we used an experimental approach based on MPM with multichannel fluorescence detection for initial discovery that MPM spectral imaging could differentiate between normal and neoplastic lung in ex vivo samples from a murine model of lung cancer. Current results indicate that MPM imaging can directly distinguish normal and neoplastic lung tissues based on their distinct morphologies and fluorescence emission properties in non-processed lung tissue. Moreover, we found initial indication that MPM imaging differentiates between normal alveolar tissue, inflammatory foci, and lung neoplasms. Our long-term goal is to apply results from ex vivo lung specimens to aid in the development of multiphoton endoscopy for in vivo imaging of lung abnormalities in various animal models, and ultimately for the diagnosis of human lung cancer.

  4. 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

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

    PubMed

    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

    2015-06-01

    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

  6. A single-photon fluorescence and multi-photon spectroscopic study of atherosclerotic lesions

    NASA Astrophysics Data System (ADS)

    Smith, Michael S. D.; Ko, Alex C. T.; Ridsdale, Andrew; Schattka, Bernie; Pegoraro, Adrian; Hewko, Mark D.; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

    2009-06-01

    In this study we compare the single-photon autofluorescence and multi-photon emission spectra obtained from the luminal surface of healthy segments of artery with segments where there are early atherosclerotic lesions. Arterial tissue was harvested from atherosclerosis-prone WHHL-MI rabbits (Watanabe heritable hyperlipidemic rabbit-myocardial infarction), an animal model which mimics spontaneous myocardial infarction in humans. Single photon fluorescence emission spectra of samples were acquired using a simple spectrofluorometer set-up with 400 nm excitation. Samples were also investigated using a home built multi-photon microscope based on a Ti:sapphire femto-second oscillator. The excitation wavelength was set at 800 nm with a ~100 femto-second pulse width. Epi-multi-photon spectroscopic signals were collected through a fibre-optics coupled spectrometer. While the single-photon fluorescence spectra of atherosclerotic lesions show minimal spectroscopic difference from those of healthy arterial tissue, the multi-photon spectra collected from atherosclerotic lesions show marked changes in the relative intensity of two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) signals when compared with those from healthy arterial tissue. The observed sharp increase of the relative SHG signal intensity in a plaque is in agreement with the known pathology of early lesions which have increased collagen content.

  7. Activatable Organic Near-Infrared Fluorescent Probes Based on a Bacteriochlorin Platform: Synthesis and Multicolor in Vivo Imaging with a Single Excitation

    PubMed Central

    2015-01-01

    Near infrared (NIR) fluorescent probes are ideal for in vivo imaging because they offer deeper tissue penetration and lower background autofluorescence. Although most fluorophores in this range are cyanine-based dyes, several new classes of fluorescent NIR probes have been developed. In this study, we developed organic bacteriochlorin derivatives, NMP4 and NMP5, which are excited with a single green light and emit different narrow, well-resolved bands in the NIR (peak of 739 and 770 nm for NMP4 and NMP5, respectively). When conjugated to galactosyl-human serum albumin (hGSA) or glucosyl-human serum albumin (glu-HSA), both targeting H-type lectins, including the ?-d-galactose receptor expressing on ovarian cancer, these agents become targeted, activatable, single excitation, multicolor NIR fluorescence probes. After conjugation to either glu-HSA or hGSA, substantial quenching of fluorescence occurs that is reversed after cell binding and internalization. In vitro studies showed higher cancer cell uptake with NMP4 or NMP5 conjugated to hGSA compared to the same conjugates with glu-HSA. In vivo single excitation two-color imaging was performed after intraperitoneal injection of these agents into mice with disseminated ovarian cancer. Excited with a single green light, distinct NIR emission spectra from each fluorophore were detected and could be distinguished with spectral unmixing. In vivo results using a red fluorescence protein (RFP) labeled tumor model of disseminated ovarian cancer demonstrated high sensitivity and specificity for all probes. The success of single excitation, 2-color NIR fluorescence imaging with a new class of bacteriochlorin-based activatable fluorophores, NMP4 and NMP5, paves the way for further exploration of noncyanine dye-based NIR fluorophores. PMID:24450401

  8. Measurements of multiphoton action cross sections for multiphoton microscopy.

    PubMed

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

    2014-10-01

    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

  9. 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

  10. Polarization phenomena in multiphoton ionization of atoms

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.

    1973-01-01

    The theory of multiphoton ionization for an atomic system of arbitrary complexity is developed using a density matrix formalism. An expression is obtained which determines the differential N-photon ionization cross section as a function of the polarization states of the target atom and the incident radiation. The parameters which characterize the photoelectron angular distribution are related to the general reduced matrix elements for the N-photon transition. Two-photon ionization of unpolarized atoms is treated as an illustration of the use of the theory. The dependence of the multiphoton ionization cross section on the polarization state of the incident radiation, which has been observed in two- and three-photon ionization of Cs, is accounted for by the theory. Finally, the photoelectron spin polarization produced by the multiphoton ionization of unpolarized atoms, like the analogous polarization resulting from single-photon ionization, is found to depend on the circular polarization of the incident radiation.

  11. 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.

  12. Intravital multiphoton microscopy for imaging hepatobiliary function

    NASA Astrophysics Data System (ADS)

    Lo, Wen; Liu, Yuan; Chen, Hsiao-Ching; Yang, Shu-Mei; Sun, Tzu-Lin; Chiou, Ling-Ling; Huang, Guan-Tarn; Dong, Chen-Yuan; Lee, Hsuan-Shu

    2007-02-01

    In this work, intravital multiphoton microscopy is applied to the imaging of liver metabolism with the least invasiveness. We observed intravital dynamics of the uptake, processing and excretion of the organic anion species, 6-carboxyfluorescein diacetate (6-CFDA) in the hepatobiliary system. This is achieved by the use of multiphoton microscopy and an in vivo hepatic imaging chamber which allows us to image the dynamics of hepatic metabolism. Multiphoton images revealed that the hepatic processing of 6-CFDA is completed within approximately 50 minutes. The images reveal the liver metabolism of the uptake and processing of 6-CFDA from the hepatocytes, and the subsequent excretion into bile canaliculi. Our results suggest that this approach is a promising technique for investigating intravital hepatic physiology, diseases, and metabolism.

  13. Influence of multiphoton events in measurement of two-photon absorption cross-sections and optical nonlinear parameters under femtosecond pumping

    NASA Astrophysics Data System (ADS)

    Sailaja, Rallabandi; Bisht, Prem B.; Singh, C. P.; Bindra, K. S.; Oak, S. M.

    2007-09-01

    Absolute values of two-photon absorption cross-sections of some laser dyes in methanol solution have been measured by using the transmission method. From the fluorescence yield measurements under multiphoton excitation, the number of involved photons in the process has also been estimated. It is found that the presence of higher photon events may lead to erroneous values of measured two-photon absorption cross-sections. It is shown here that the Z-scan technique is capable of differentiating between the two- and three-photon absorption processes. Nonlinear optical parameters under femtosecond pumping by multiphoton resonant excitation at 800 nm are also given here.

  14. 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.

  15. Multiphoton ionization/dissociation of cyclopentanone at the lower Rydberg states

    SciTech Connect

    Philis, John G.; Kosmidis, Constantine; Tzallas, Paraskevas [Department of Physics, University of Ioannina, GR45110 Ioannina (Greece)

    1998-12-16

    The 2-photon excitation of the 3p and 3d Rydberg states in jet-cooled cyclopentanone has been investigated by resonance enhanced multiphoton ionization (REMPI) in a time of flight mass spectrometer. The three 3p{sub x,y,z} components are clearly resolved while the case for the 3d{sub i} excitations is obscure due to the S{sub 1} one-photon resonance. The ns laser induced mass spectra are characteristic of hard ionization while the fs laser induced mass spectrum is very similar to the Electron Impact one.

  16. High resolution multiphoton spectroscopy by a tunable free-electron-laser light.

    PubMed

    Žitnik, M; Miheli?, A; Bu?ar, K; Kav?i?, M; Rubensson, J-E; Svanquist, M; Söderström, J; Feifel, R; Såthe, C; Ovcharenko, Y; Lyamayev, V; Mazza, T; Meyer, M; Simon, M; Journel, L; Lüning, J; Plekan, O; Coreno, M; Devetta, M; Di Fraia, M; Finetti, P; Richter, R; Grazioli, C; Prince, K C; Callegari, C

    2014-11-01

    Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)(+1) (1)S(e) and (0,1)(0) (1)D(e) resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates. PMID:25415905

  17. Intramolecular vibrational energy redistribution and conformational isomerization in vibrationally excited 2-fluoroethanol: High-resolution, microwave-infrared double-resonance spectroscopy investigation of the asymmetric CH2(F) stretch near 2980 cm-1

    Microsoft Academic Search

    David Green; Sarah Hammond; John Keske; Brooks H. Pate

    1999-01-01

    The asymmetric -CH2(F) stretch spectrum of 2-fluoroethanol near 2980 cm-1 has been rotationally assigned using microwave-infrared double-resonance spectroscopy methods in an electric-resonance optothermal molecular-beam spectrometer. The eigenstate-resolved infrared spectrum shows the effects of intramolecular vibrational energy redistribution (IVR) through the fragmentation of each rotational level of the vibrationally excited state into a set of transitions. From the spectrum we determine

  18. Exploration of the subcycle multiphoton ionization dynamics and transient electron density structures with Bohmian trajectories

    NASA Astrophysics Data System (ADS)

    Jooya, Hossein Z.; Telnov, Dmitry A.; Li, Peng-Cheng; Chu, Shih-I.

    2015-06-01

    An accurate three-dimensional numerical scheme for the De Broglie-Bohm framework of Bohmian mechanics is presented. This method is utilized to explore the subcycle multiphoton ionization dynamics of the hydrogen atom subject to intense near-infrared laser fields on the subfemtosecond time scale. The analysis of the time-dependent electron density reveals that several distinct density portions can be shaped and detached from the core within a half cycle of the laser field. As a complementary perspective, we identify several distinct groups of the Bohmian trajectories which represent the multiple detachments of the electron density at different times. The method presented provides very accurate electron densities and Bohmian trajectories that allow to uncover the origin of the formation of the transient and distinct electron structures seen in the multiphoton ionization processes.

  19. 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.

  20. 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.

  1. Autoionizing decay of H2 doubly excited states by using xuv-pump-infrared-probe schemes with trains of attosecond pulses

    NASA Astrophysics Data System (ADS)

    Silva, R. E. F.; Rivière, P.; Martín, F.

    2012-06-01

    We present a theoretical study of H2 ionization by a pump-probe scheme consisting on an attosecond pulse train (APT) and a near-infrared (IR) pulse. We focus on the autoionization dynamics of the first series of resonant states of the molecule, the Q1 doubly excited states. The APT central frequency is tuned to populate the 1?u+ resonant states. The trace of autoionization is clearly visible in the two-dimensional (2D) proton-electron coincidence spectra and in the proton kinetic energy spectra. The dynamics of the autoionization process is clearly visible in the movie obtained by plotting the 2D spectrum as a function of the time delay between the APT and IR pulses. An analysis of the final symmetries ?g and ?u allows us to track the origin of the different structures.

  2. Charged-particle emission from dielectric materials initiated by a tunable picosecond mid-infrared laser

    NASA Astrophysics Data System (ADS)

    Ermer, David R.; Papantonakis, Michael R.; Baltz-Knorr, Michelle; Haglund, Richard F., Jr.

    2000-03-01

    In the ultraviolet, visible and near-infrared, single and multiphoton electronic transitions can explain the production and emission of charged atoms, molecules and photoelectrons during laser ablation and desorption. However, the process of charge transfer and ionization during ablation of dielectrics in the mid-infrared is not well understood. Even though significant electronic excitation is unlikely, copious emission of charged particles, e.g. atoms, molecules and electrons, is observed. No evidence of laser plume interactions is observed and inverse Bremsstrahlung (IB) is ruled out as a primary ionization/charge transfer mechanism. By irradiating with an ultrashort pulse-width mid-infrared laser tuned to a vibrational resonance it is possible to generate a high vibrational excitation density in dielectric materials. This high excitation density creates a non- equilibrium state of matter that exists until the deposited energy fully thermalizes. In this paper we report measurements of the kinetic energy of ions and electrons from CaCO3, NaNO3 and dihydroxybenzoic (DHB) acid that are highly non- thermal. This non-thermal energy distribution is evidence that the primary production of charged species occurs while the material is in a non-equilibrium state. The fact that it occurs in quite different materials, and without some of the characteristic signatures of electronically induced desorption and ionization, points toward a new mechanism.

  3. Deep tissue multiphoton microscopy using longer wavelength excitation

    E-print Network

    Schaffer, Chris B.

    ," Nat. Methods 2, 932-940 (2005). 5. P. Theer, M.T. Hasan, and W. Denk, "Two-photon imaging to a depth). 7. S. Sakadzi, U. Demirbas, T.R. Mempel, A. Moore, S. Ruvinskaya, D.A. Boas, A. Sennaroglu, F in two-photon microscopy," J. Opt. Soc. Am. A 23, 3139-3149 (2006). 9. A.N. Yaroslavsky, P.C. Schulze, I.V

  4. Comparative study of first- and second-order Raman spectra of MWCNT at visible and infrared laser excitation

    Microsoft Academic Search

    E. F. Antunes; A. O. Lobo; E. J. Corat; V. J. Trava-Airoldi; A. A. Martin; C. Veríssimo

    2006-01-01

    Comparative studies of first- and second-order Raman spectra of multi-walled carbon nanotubes (MWCNT) and three other graphitic materials – carbon fiber, powdered graphite and highly ordered pyrolytic graphite – are reported. Three laser excitation wavelengths were used: 514.5, 785 and 1064nm. In first-order Raman spectra, the positions of the bands D, G and D? (1100–1700cm?1) presented very similar behavior, however

  5. Demodulation signal processing in multiphoton imaging

    Microsoft Academic Search

    Walter G. Fisher; Eric A. Wachter; David W. Piston

    2002-01-01

    Multiphoton laser scanning microscopy offers numerous advantages, but sensitivity can be seriously affected by contamination from ambient room light. Typically, this forces experiments to be performed in an absolutely dark room. Since mode-locked lasers are used to generate detectable signals, signal-processing can be used to avoid such problems by taking advantage of the pulsed characteristics of such lasers. Demodulation of

  6. Multiphoton processes in driven mesoscopic systems

    E-print Network

    Fominov, Yakov

    : Vladimir Falko Alessandro Silva ICTP Trieste #12;Motivation · Driven mesoscopic systems: diffusionMultiphoton processes in driven mesoscopic systems Collaboration: Vladimir Kravtsov Discussion =--+--+ ---+---++ + t ttttt fteAteAteAteA ttttCdtDfteAteADf Physical content: suppression diffusion slow down absorbtion #12

  7. Multiphoton wave function after Kerr interaction

    NASA Astrophysics Data System (ADS)

    Koshino, Kazuki

    2008-08-01

    The multiphoton wave function after Kerr interaction is obtained analytically for an arbitrary photon number. The wave function is composed of two fundamental functions: the input mode function and the linear response function. The nonlinear effects appearing in this wave function are evaluated quantitatively, revealing the limitations of nonlinear quantum optics theories based on single-mode approximations.

  8. Entanglement Persistency of Multiphoton Entangled States

    NASA Astrophysics Data System (ADS)

    Bourennane, Mohamed; Eibl, Manfred; Gaertner, Sascha; Kiesel, Nikolai; Kurtsiefer, Christian; Weinfurter, Harald

    2006-03-01

    We experimentally demonstrate the entanglement persistency when losing photons in three- and four-photon polarization-entangled states. The entanglement properties of the mixed states obtained from multiphoton spontaneous parametric down-conversion are studied via witness and positive partial transpose approaches. Together with a quantification of the bipartite entanglement such analysis enables intuitive understanding of novel multiparty quantum communication protocols.

  9. Nonlinear magic: multiphoton microscopy in the biosciences

    Microsoft Academic Search

    Warren R Zipfel; Rebecca M Williams; Watt W Webb

    2003-01-01

    Multiphoton microscopy (MPM) has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals. Coupled with transgenic mouse models of disease and 'smart' genetically encoded fluorescent indicators, its use is now increasing exponentially. Properly applied, it is capable of measuring calcium transients 500 ?m deep in a

  10. Bioinspired near-infrared-excited sensing platform for in vitro antioxidant capacity assay based on upconversion nanoparticles and a dopamine-melanin hybrid system.

    PubMed

    Wang, Dong; Chen, Chuan; Ke, Xuebin; Kang, Ning; Shen, Yuqing; Liu, Yongliang; Zhou, Xi; Wang, Hongjun; Chen, Changqing; Ren, Lei

    2015-02-11

    A novel core-shell structure based on upconversion fluorescent nanoparticles (UCNPs) and dopamine-melanin has been developed for evaluation of the antioxidant capacity of biological fluids. In this approach, dopamine-melanin nanoshells facilely formed on the surface of UCNPs act as ultraefficient quenchers for upconversion fluorescence, contributing to a photoinduced electron-transfer mechanism. This spontaneous oxidative polymerization of the dopamine-induced quenching effect could be effectively prevented by the presence of various antioxidants (typically biothiols, ascorbic acid (Vitamin C), and Trolox). The chemical response of the UCNPs@dopamine-melanin hybrid system exhibited great selectivity and sensitivity toward antioxidants relative to other compounds at 100-fold higher concentration. A satisfactory correlation was established between the ratio of the "anti-quenching" fluorescence intensity and the concentration of antioxidants. Besides the response of the upconversion fluorescence signal, a specific evaluation process for antioxidants could be visualized by the color change from colorless to dark gray accompanied by the spontaneous oxidation of dopamine. The near-infrared (NIR)-excited UCNP-based antioxidant capacity assay platform was further used to evaluate the antioxidant capacity of cell extracts and human plasma, and satisfactory sensitivity, repeatability, and recovery rate were obtained. This approach features easy preparation, fluorescence/visual dual mode detection, high specificity to antioxidants, and enhanced sensitivity with NIR excitation, showing great potential for screening and quantitative evaluation of antioxidants in biological systems. PMID:25604145

  11. 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.

  12. 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.

  13. 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.

  14. Stability of cetrimonium and silica modified gold nanorods/polyvinyl alcohol nano-composites upon near infrared laser excitation

    NASA Astrophysics Data System (ADS)

    Ratto, Fulvio; Matteini, Paolo; Centi, Sonia; Rossi, Francesca; Pini, Roberto

    2010-02-01

    We provide novel insight into the photothermal stability of different solutions of gold nanorods embedded in a semi-solid PVA environment, which may produce different effects with respect e.g. to the aqueous colloidal suspension. We investigate gold nanorods with different average dimensions and surface modifications (cetrimonium bromide (CTAB) and porous silica (p-silica)). Under near-infrared laser pulses between 20 ms and 20 s, the effective photothermal stability is higher in large than in small nanoparticles and in CTAB-protected than in p-silica-modified nanoparticles. At least up to ~200 °C there occurs only partial deformation of the gold nanorods with negligible formation of stable byproducts. We understand these results as the interplay of different factors, including the protection exerted from the semi-solid environment and the aggregation of the nanoparticles.

  15. Kinetic studies following state-selective laser excitation. Progress report, May 1, 1991--April 29, 1992

    SciTech Connect

    Keto, J.W.

    1992-01-01

    We have made measurements of state-to-state deactivation cross sections and radiative lifetimes for Xe*(6p,6p{prime},7p) and Kr*(5p) states in xenon and krypton buffer gases. These results are relevant to kinetic models and both excimer lasers and the infrared xenon laser; and they are a significant improvement in the precision of the known radiative lifetimes. This type of experiment can now be compared with recent calculations of state-to-state collisional relaxation in rare-gases by Hickman, Huestis, and Saxon. We have also made significant progress in the study of the electronic spectra of small molecules of the rare gases. Spectra have been obtained for Xe{sub 2}, Xe{sub 3}, Xe{sub 4}, and larger clusters. As guidance for the larger clusters of the rare gases we have obtained the first multiphoton spectra for excitons in condensed xenon. In collaboration with research on the multiphoton spectra of the rare gases, we have continued experiments using synchrotron radiation in collaboration with the University of Hamburg. In experiments there we have observed excitation and fluorescence spectra for single xenon atoms at the surface, within the second layer, and within the bulk of large argon clusters.

  16. 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.

  17. Intrinsic Indicator of Photodamage during Label-Free Multiphoton Microscopy of Cells and Tissues

    PubMed Central

    Andresen, Elisabeth F.; Geiger, Kathrin D.; Koch, Edmund; Schackert, Gabriele; Steiner, Gerald; Kirsch, Matthias

    2014-01-01

    Multiphoton imaging has evolved as an indispensable tool in cell biology and holds prospects for clinical applications. When addressing endogenous signals such as coherent anti-Stokes Raman scattering (CARS) or second harmonic generation, it requires intense laser irradiation that may cause photodamage. We report that increasing endogenous fluorescence signal upon multiphoton imaging constitutes a marker of photodamage. The effect was studied on mouse brain in vivo and ex vivo, on ex vivo human brain tissue samples, as well as on glioblastoma cells in vitro, demonstrating that this phenomenon is common to a variety of different systems, both ex vivo and in vivo. CARS microscopy and vibrational spectroscopy were used to analyze the photodamage. The development of a standard easy-to-use model that employs rehydrated cryosections allowed the characterization of the irradiation-induced fluorescence and related it to nonlinear photodamage. In conclusion, the monitoring of endogenous two-photon excited fluorescence during label-free multiphoton microscopy enables to estimate damage thresholds ex vivo as well as detect photodamage during in vivo experiments. PMID:25343251

  18. In vivo multiphoton imaging of collagen remodeling after microablative fractional rejuvenation

    NASA Astrophysics Data System (ADS)

    Cicchi, Riccardo; Kapsokalyvas, Dimitrios; Troiano, Michela; Campolmi, Piero; Morini, Cristiano; Cosci, Alessandro; Massi, Daniela; Lotti, Torello; Pavone, Francesco S.

    2011-03-01

    The potential of multiphoton microscopy in providing in-vivo early diagnosis of skin lesions has already been demonstrated, while its capability in therapy follow-up has not been deeply explored so far. Two-photon excited fluorescence and second-harmonic generation microscopy were used in combination to follow-up collagen remodeling after laser micro-ablative rejuvenation. Treated regions of volunteers were imaged with multiphoton microscopy before and after treatment, and we found a strong age-dependence of the treatment effectiveness. In particular, the photorejuvenating effect was negligible in young subjects (< 30 years), whereas a significant production of new collagen was observed in aged subjects (> 70 years). Quantification of the amount of newly produced collagen and its organization were performed by means of visual examination of two-photon images. The obtained results demonstrate the performance of laser fractional micro-ablative rejuvenation without the need of an invasive biopsy as well as the wide applicability range of applications for multiphoton microscopy in clinical dermatology.

  19. Multiphoton Imaging of Renal Regulatory Mechanisms

    NSDL National Science Digital Library

    Janos Peti-Peterdi (Departments of Physiology and Biophysics and Medicine)

    2009-04-01

    Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and previously inaccessible structures in many organ parts that have been difficult to study. Multiphoton fluorescence microscopy offers a state-of-the-art imaging technique for deep optical sectioning of living tissues and organs with minimal deleterious effects. Dynamic regulatory processes and multiple functions in the intact kidney can be quantitatively visualized in real time, noninvasively, and with submicron resolution. This article reviews innovative multiphoton imaging technologies and their applications that provided the most complex, immediate, and dynamic portrayal of renal functionÂ?clearly depicting as well as analyzing the components and mechanisms involved in renal (patho)physiology.

  20. High-resolution infrared studies in slit supersonic discharges: CH2 stretch excitation of jet-cooled CH2Cl radical.

    PubMed

    Whitney, Erin S; Haeber, Thomas; Schuder, Michael D; Blair, Andrew C; Nesbitt, David J

    2006-08-01

    First high-resolution infrared spectra are presented for jet-cooled CH2 35Cl and CH2 37Cl radicals in the symmetric (nu1) CH2 stretching mode. A detailed spectral assignment yields refined lower and upper state rotational constants, as well as fine structure spin-rotation parameters from least-squares fits to the sub-Doppler line shapes for individual transitions. The rotational constants are consistent with a nearly planar structure, but do not exclude substantial large amplitude bending motion over a small barrier to planarity accessible with zero-point excitation. High level coupled cluster (singles/doubles/triples) calculations, extrapolated to the complete basis set limit, predict a slightly nonplanar equilibrium structure (theta approximately 11 degrees), with a vibrationally adiabatic treatment of the bend coordinate yielding a v = 1<--0 anharmonic frequency (393 cm(-1)) in excellent agreement with matrix studies (nu(bend) approximately 400 cm(-1)). The antisymmetric CH2 stretch vibration is not observed despite high sensitivity detection (signal to noise ratio >20:1) in the symmetric stretch band. This is consistent with density functional theory intensity calculations indicating a >35-fold smaller antisymmetric stretch transition moment for CH2Cl, and yet contrasts dramatically with high-resolution infrared studies of CH2F radical, for which both symmetric and antisymmetric CH2 stretches are observed in a nearly 2:1 intensity ratio. A simple physical model is presented based on a competition between bond-dipole and "charge-sloshing" contributions to the transition moment, which nicely explains the trends in CH2X symmetric versus asymmetric stretch intensities as a function of electron withdrawing group (X = D,Br,Cl,F). PMID:16942209

  1. Phase sensitive demodulation in multiphoton microscopy.

    PubMed

    Fisher, Walt G; Piston, David W; Wachter, Eric A

    2002-06-01

    Multiphoton laser scanning microscopy offers advantages in depth of penetration into intact samples over other optical sectioning techniques. To achieve these advantages it is necessary to detect the emitted light without spatial filtering. In this nondescanned (nonconfocal) approach, ambient room light can easily contaminate the signal, forcing experiments to be performed in absolute darkness. For multiphoton microscope systems employing mode-locked lasers, signal processing can be used to reduce such problems by taking advantage of the pulsed characteristics of such lasers. Specifically, by recovering fluorescence generated at the mode-locked frequency, interference from stray light and other ambient noise sources can be significantly reduced. This technology can be adapted to existing microscopes by inserting demodulation circuitry between the detector and data collection system. The improvement in signal-to-noise ratio afforded by this approach yields a more robust microscope system and opens the possibility of moving multiphoton microscopy from the research lab to more demanding settings, such as the clinic. PMID:12533235

  2. Spectroscopic probes of vibrationally excited molecules at chemically significant energies

    SciTech Connect

    Rizzo, T.R.

    1992-03-01

    These experiments apply multiple-laser spectroscopic techniques to investigate the bond energies, potential surface topologies, and dissociation dynamics of highly vibrationally excited molecules. Infrared-optical double resonance pumping of light atom stretch vibrations in H{sub 2}O{sub 2} and HN{sub 3} prepares reactant molecules in single rovibrational states above the unimolecular dissociation threshold on the ground potential surface, and laser induced fluorescence detection of the OH or NH fragments monitors the partitioning of energy into individual product quantum states. Product energy partitioning data from H{sub 2}O{sub 2} dissociation provide a stringent test of statistical theories as well as potential energy surface calculations. Ongoing work on HN{sub 3} seeks to determine the height of the barrier to dissociation on the singlet potential energy surface. Our most recently developed spectroscopic scheme allows the measurement of high vibrational overtone spectra of jet-cooled molecules. This approach uses CO{sub 2} laser infrared multiphoton dissociation followed by laser induced fluorescence product detection to measure weak vibrational overtone transitions in low pressure environments. Application of this scheme to record the {Delta}V{sub OH}=4 and {Delta}V{sub OH}=5 transitions of CH{sub 3}OH cooled in a supersonic free-jet demonstrates both its feasibility and its utility for simplifying high vibrational overtone spectra.

  3. 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.

  4. Imaging the ``missing'' bands in the resonance-enhanced multiphoton ionization detection of methyl radical

    NASA Astrophysics Data System (ADS)

    Zhang, Bailin; Zhang, Jinghui; Liu, Kopin

    2005-03-01

    Three small features were uncovered in the (2+1) resonance-enhanced multiphoton ionization spectra of CD3 produced from a crossed-beam reaction of F +CHD3 near reaction threshold. Taking the velocity mapped images of these features revealed several well-resolved ringlike structures. By conservation of energy, these spectral features were unambiguously assigned to the "missing" bands of 111, 311, and 411 in the literature. These assignments enable all four modes of excitation of this important radical being detected, which could have significant impact on future dynamics studies of the mode specificity of methyl radical.

  5. 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

  6. Photoionization of excited molecular states. H 2 C 1? u

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.

    1984-03-01

    We present photoelectron spectra for H 2 in the excited C 1? u, ? = 0-4. J = 1 levels prepared by multiphoton excitation. In accordance with the Franck-Condon principle, the H 2+ vibrational state distribution is dominated by ?? = 0 transitions from the C 1? u state, illustrating a useful method for preparing vibrationally state-selected molecular ions. Equally important observed systematic departures from Franck-Condon factors, which provide detailed information on excited-state photoionization dynamics of molecules.

  7. Rotation-torsion analysis of the Si2H6 infrared fundamental ?, perturbed by excited torsional levels of the vibrational ground state

    NASA Astrophysics Data System (ADS)

    Lattanzi, F.; di Lauro, C.; Horneman, V.-M.

    The lowest infrared active perpendicular fundamental ?9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430 cm-1, at the spectral resolution of 0.0012 cm-1. The rotation-torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3?4 and 4?4 in the high barrier limit. The interaction of ?9 and 4?4, forbidden in the D3d symmetry limit, is allowed between components of E torsional symmetry under the G36(EM) extended molecular group, because of the large amplitude of the internal rotation motion. We could determine the values of the main vibration-rotation-torsion parameters of ?9, interaction parameters, and the vibrational wavenumbers of the four torsional components of 3?4 and of the E3d component of 4?4. The intrinsic torsional splitting of ?9 is found to be smaller than in the ground vibrational state by 0.0066 cm-1, in good agreement with our theoretical predictions. The possibility of observing the effects of D3d-forbidden interactions in the spectra of ethane-like molecules is also discussed.

  8. 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.

  9. 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

  10. Efficient laser heating of transparent liquids using multiphoton absorption

    Microsoft Academic Search

    Jon P. Longtin; Chang-Lin Tien

    1997-01-01

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in heating and temperature increases orders of magnitude greater than that from classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for significant, controlled energy deposition in transparent liquids, which is important for a variety of laser-liquid technologies. This work

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

    SciTech Connect

    Holtom, Gary R. (BATTELLE (PACIFIC NW LAB)); Thrall, Brian D. (BATTELLE (PACIFIC NW LAB)); Chin, Beek Yoke (BATTELLE (PACIFIC NW LAB)); Wiley, H Steven (BATTELLE (PACIFIC NW LAB)); Colson, Steven D. (BATTELLE (PACIFIC NW LAB))

    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.

  12. Resonant excitations of single and two-qubit systems coupled to a tank circuit

    E-print Network

    Shevchenko, S N; Grajcar, M; Ilyichev, E; Omelyanchouk, A N; Meyer, H -G

    2008-01-01

    The interaction of flux qubits with a low frequency tank circuit is studied. It is shown that changes in the state of the interacting qubits influence the effective impedance of the circuit, which is the essence of the so-called impedance measurement technique. The multiphoton resonant excitations in both single flux qubits and pairs of coupled flux qubits are investigated. In particular, we compare our theoretical results with recent spectroscopy measurements, Landau-Zener interferometry, and multiphoton fringes.

  13. Resonant excitations of single and two-qubit systems coupled to a tank circuit

    E-print Network

    S. N. Shevchenko; S. H. W. van der Ploeg; M. Grajcar; E. Il'ichev; A. N. Omelyanchouk; H. -G. Meyer

    2008-12-01

    The interaction of flux qubits with a low frequency tank circuit is studied. It is shown that changes in the state of the interacting qubits influence the effective impedance of the circuit, which is the essence of the so-called impedance measurement technique. The multiphoton resonant excitations in both single flux qubits and pairs of coupled flux qubits are investigated. In particular, we compare our theoretical results with recent spectroscopy measurements, Landau-Zener interferometry, and multiphoton fringes.

  14. The multiphoton ionization of uranium hexafluoride. Revision 1

    SciTech Connect

    Armstrong, D.P. [Oak Ridge K-25 Site, TN (United States). UEO Enrichment Technical Operations Div.] [Oak Ridge K-25 Site, TN (United States). 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.

  15. Nonresonant multiphoton ionization in atomic hydrogen

    SciTech Connect

    Radhakrishnan, R.; Thayyullathil, Ramesh Babu [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India)

    2004-03-01

    The infinite summations over the complete set of unperturbed atomic states appearing in the Nth-order perturbation theory for multiphoton ionization are performed using the Dalgarno-Lewis method. The relevant transition matrix elements are written in a closed integral form exhibiting all the analytic properties of the amplitude as a function of incident photon energy. The cross sections for two- and three-photon ionization for atomic hydrogen are calculated for both linearly and circularly polarized light with a wide range of photon energy spectrum including the near resonance, and numerical comparison is made with the values obtained by different methods.

  16. Femtosecond coincidence imaging of multichannel multiphoton dynamics.

    PubMed

    Rijs, Anouk M; Janssen, Maurice H M; Chrysostom, Engelene T H; Hayden, Carl C

    2004-03-26

    The novel technique of femtosecond time-resolved photoelectron-photoion coincidence imaging is applied to unravel dissociative ionization processes in a polyatomic molecule. Femtosecond coincidence imaging of CF3I photodynamics illustrates how competing multiphoton dissociation pathways can be distinguished, which would be impossible using photoelectron or ion imaging alone. Ion-electron energy correlations and photoelectron angular distributions reveal competing processes for the channel producing (e(-)+CF+3+I). The molecular-frame photoelectron angular distributions of the two major pathways are strikingly different. PMID:15089669

  17. 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.

  18. Monodispersed LaF3 nanocrystals: shape-controllable synthesis, excitation-power-dependent multi-color tuning and intense near-infrared upconversion emission.

    PubMed

    Rao, Ling; Lu, Wei; Ren, Guozhong; Wang, Haibo; Yi, Zhigao; Liu, Hongrong; Zeng, Songjun

    2014-02-14

    In this study, monodispersed and high-quality hexagonal phase LaF3 nanocrystals with different shapes and sizes were synthesized by a solvothermal method using oleic acid as the stabilizing agent. The as-prepared LaF3 nanocrystals were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), and analysis of the upconversion spectra. The TEM results reveal that the samples present high uniformity and monodispersity and are self-assembled into a two-dimensional ordered array. Moreover, the shape, size and structure of the nanocrystals can be readily tuned by adjusting the NaF content. With increasing content of NaF, the shape of the LaF3 nanocrystals changed from particle to rod and the size gradually increased. More importantly, high NaF content favors the formation of one-dimensional nanorods. High Y b(3+) and Er(3+) content is beneficial to synthesizing the hexagonal phase of NaLaF4 nanocrystals. Furthermore, the TEM results show that the shape and size of the LaF3 nanocrystals can also be tuned by doping lanthanide ions, which provides a new route for size and shape control of nanocrystals. In addition, LaF3 nanocrystals co-doped with Y b(3+)/Tm(3+) present efficient near-infrared (NIR)-NIR upconversion luminescence. More importantly, the upconversion luminescent colors can be readily tuned from blue-white to blue by adjusting the excitation power. Therefore, it is expected that these LaF3 nanocrystals with well-controlled shape, size and NIR-NIR upconversion emission have potential applications in biomedical imaging fields. PMID:24434274

  19. a UV+VUV Multiphoton Ionization Scheme for OH Radicals

    NASA Astrophysics Data System (ADS)

    Beames, Joseph M.; Liu, Fang; Lester, Marsha I.

    2012-06-01

    OH radicals are of significant atmospheric interest as a dominant oxidizing agent in day-time tropospheric chemistry. In this study, a 1+1' multiphoton ionization (MPI) scheme is employed to record rotationally-resolved spectra of OH radicals via the A^2?^+ resonant intermediate state. UV excitation is used to prepare OH A^2?^+(v=1, {J}, F_i), which is subsequently ionized by a second photon of fixed frequency VUV (118.3 nm), generated by tripling the 355 nm output of a Nd:YAG laser. The mass-selected OH^+ ion signal from 1+1' MPI is detected using time-of flight mass spectrometry and compared with the laser-induced fluorescence (LIF) signal arising from OH A^2?^+-X^2?(1,0) excitation. The MPI signal is observed over a range of UV+VUV total energies, corresponding to various OH A^2?^+ (v=1, {J}, F_i) intermediate states, with relative intensities that differ considerably from LIF. The ion signal is enhanced relative to LIF at combined UV + VUV photon energies consistent with an autoionizing 3{d} Rydberg state that converges on the OH^+ A^3? ion core; direct ionization into OH^+ X^3?^- is forbidden in a one-photon electric-dipole transition from OH A^2?^+. The MPI intensities have been quantified relative to LIF over the OH A^2?^+-X^2?(1,0) region such that this scheme is now applicable for quantitative state-selective detection of OH X^2?. J. M. Beames, F. Liu, M. I. Lester and C. Murray, J. Chem. Phys. 134, 241102 (2011). J. D. Barr, A. De Fanis, J. M. Dyke, S. D. Gamblin, N. Hooper, A. Morris, S. Stranges, J. B. West, and T. G. Wright, J. Chem. Phys. 110, 345 (1999).

  20. Multiphoton Photochemistry of Red Fluorescent Proteins in Solution and Live Cells

    PubMed Central

    2015-01-01

    Genetically encoded fluorescent proteins (FPs), and biosensors based on them, provide new insights into how living cells and tissues function. Ultimately, the goal of the bioimaging community is to use these probes deep in tissues and even in entire organisms, and this will require two-photon laser scanning microscopy (TPLSM), with its greater tissue penetration, lower autofluorescence background, and minimum photodamage in the out-of-focus volume. However, the extremely high instantaneous light intensities of femtosecond pulses in the focal volume dramatically increase the probability of further stepwise resonant photon absorption, leading to highly excited, ionizable and reactive states, often resulting in fast bleaching of fluorescent proteins in TPLSM. Here, we show that the femtosecond multiphoton excitation of red FPs (DsRed2 and mFruits), both in solution and live cells, results in a chain of consecutive, partially reversible reactions, with individual rates driven by a high-order (3–5 photon) absorption. The first step of this process corresponds to a three- (DsRed2) or four-photon (mFruits) induced fast isomerization of the chromophore, yielding intermediate fluorescent forms, which then subsequently transform into nonfluorescent products. Our experimental data and model calculations are consistent with a mechanism in which ultrafast electron transfer from the chromophore to a neighboring positively charged amino acid residue triggers the first step of multiphoton chromophore transformations in DsRed2 and mFruits, consisting of decarboxylation of a nearby deprotonated glutamic acid residue. PMID:25004113

  1. Multiphoton ionization of large water clusters

    SciTech Connect

    Apicella, B., E-mail: apicella@irc.cnr.it [Combustion Research Institute, IRC–C.N.R., P.le Tecchio 80, 80125 Napoli (Italy); Li, X. [Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240 (China); Passaro, M. [CNISM and Chemical Engineering, Materials and Industrial Production Department, University of Naples “Federico II,” P.le Tecchio 80, 80125 Napoli (Italy); Spinelli, N. [CNISM and Physics Department, University of Naples “Federico II,” Via Cintia, 80124 Napoli (Italy); Wang, X. [SPIN–C.N.R., Via Cintia, 80124 Napoli (Italy)

    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.

  2. Multiphoton ionization of large water clusters.

    PubMed

    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. PMID:24880286

  3. Multiphoton ionization of large water clusters

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    PubMed Central

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

    2012-01-01

    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. MPM images of different biological tissues acquired by the compact system which integrates an FBFP laser, an DCPCF and a miniature handheld probe. PMID:20635426

  5. 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.

  6. Dynamic Multiphoton Imaging: A Live View from Cells to Systems

    NSDL National Science Digital Library

    PhD Grace E. Stutzmann (University of California-Irvine)

    2005-02-01

    The application of multiphoton microscopy to the biological sciences has led to a new generation of imaging-based studies extending from the tracking of individual molecules within living cells to the observation of whole organisms

  7. A statistical model for multiphoton calcium imaging of the brain

    E-print Network

    Malik, Wasim Q.

    Multiphoton calcium fluorescence imaging has gained prominence as a valuable tool for the study of brain cells, but the corresponding analytical regimes remain rather naive. In this paper, we develop a statistical framework ...

  8. 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 ...

  9. Limiting Energy Loss Distributions for Multiphoton Channeling Radiation

    E-print Network

    Bondarenco, M V

    2015-01-01

    Recent results in the theory of multiphoton spectra for coherent radiation sources are overviewed, with the emphasis on channeling radiation. For the latter case, the importance of the order of resummation and averaging is illustrated. Limiting shapes of multiphoton spectra at high intensity are discussed for different channeling regimes. In some spectral regions, there emerges an approximate correspondence between the radiative energy loss and the electron integrals of motion.

  10. 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.

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

    SciTech Connect

    Yoshimi, Kazuyoshi [College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827 (Japan); Koshino, Kazuki [College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827 (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    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.

  12. Enhancing Multiphoton Rates with Quantum Memories

    NASA Astrophysics Data System (ADS)

    Nunn, J.; Langford, N. K.; Kolthammer, W. S.; Champion, T. F. M.; Sprague, M. R.; Michelberger, P. S.; Jin, X.-M.; England, D. G.; Walmsley, I. A.

    2013-03-01

    Single photons are a vital resource for optical quantum information processing. Efficient and deterministic single photon sources do not yet exist, however. To date, experimental demonstrations of quantum processing primitives have been implemented using nondeterministic sources combined with heralding and/or postselection. Unfortunately, even for eight photons, the data rates are already so low as to make most experiments impracticable. It is well known that quantum memories, capable of storing photons until they are needed, are a potential solution to this “scaling catastrophe.” Here, we analyze in detail the benefits of quantum memories for producing multiphoton states, showing how the production rates can be enhanced by many orders of magnitude. We identify the quantity ?B as the most important figure of merit in this connection, where ? and B are the efficiency and time-bandwidth product of the memories, respectively.

  13. Nonlinear magic: multiphoton microscopy in the biosciences.

    PubMed

    Zipfel, Warren R; Williams, Rebecca M; Webb, Watt W

    2003-11-01

    Multiphoton microscopy (MPM) has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals. Coupled with transgenic mouse models of disease and 'smart' genetically encoded fluorescent indicators, its use is now increasing exponentially. Properly applied, it is capable of measuring calcium transients 500 microm deep in a mouse brain, or quantifying blood flow by imaging shadows of blood cells as they race through capillaries. With the multitude of possibilities afforded by variations of nonlinear optics and localized photochemistry, it is possible to image collagen fibrils directly within tissue through nonlinear scattering, or release caged compounds in sub-femtoliter volumes. PMID:14595365

  14. 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.

  15. Multiphoton ionization and high-order harmonic generation of He, Ne, and Ar atoms in intense pulsed laser fields: Self-interaction-free time-dependent density-functional theoretical approach

    E-print Network

    Chu, Shih-I; Tong, Xiao-Min

    2001-06-12

    -field polarization), and (c) the effect of multiphoton resonant excitation. In particular, we found that the np0 valence electrons (in Ne and Ar) with lowest binding energies and electron orbital orientation parallel to the electric-field direction, make the dominant...

  16. Direct multi-photon ionizations of H+2 in intense laser fields

    NASA Astrophysics Data System (ADS)

    He, Hai-Xiang; Lu, Rui-Feng; Zhang, Pei-Yu; Han, Ke-Li; He, Guo-Zhong

    2012-04-01

    We have discussed a weak ionization channel characterized by the kinetic energy release spectra of the protons from Coulomb explosion with the sum energy over 10 eV from a hydrogen molecular ion for various vibrational states in infrared pulses. After Franck-Condon averaging of the contributions for various vibrational states, a ‘shoulder’-like cutoff structure has been obtained which is consistent with the experiment. For longer pulses, a multi-peak structure is obvious for the v = 0 state and attosecond extreme-ultraviolet pulses were adopted to search the essential physical dynamics. The reproductions of the kinetic energy release spectra from extreme-ultraviolet light indicate that the high kinetic energies of the protons must be due to the direct multi-photon ionizations. The origin of the multi-peak structure has also been investigated by the extreme-ultraviolet pulses. Time-dependent spectra reveal the nuclear wavepacket motion and the time region when charge-resonance-enhanced ionization takes place. Competitions between direct multi-photon ionizations and charge-resonance-enhanced ionizations have also been discussed for various intensities and pulse durations for the v = 0 state.

  17. 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.

  18. 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

  19. In-vivo observation of cells with a combined high-resolution multiphoton-acoustic scanning microscope.

    PubMed

    Schenkl, Selma; Weiss, Eike C; Stracke, Frank; Sauer, Daniel; Stark, Martin; Riemann, Iris; Lemor, Robert M; König, Karsten

    2007-05-01

    We present a combined multiphoton-acoustic microscope giving collocated access to the local morphological as well as mechanical properties of living cells. Both methods relay on intrinsic contrast mechanisms and dispense with the need of staining. In the acoustic part of the microscope, a gigahertz ultrasound wave is generated by an acoustic lens and the reflected sound energy is detected by the identical lens in a confocal setup. The achieved lateral resolution is in the range of 1 mum. Contrast in the images arises mainly from the local absorption of sound in the cells related to viscose damping. Additionally, acoustic microscopy can access the sound speed as well as the acoustic impedance of the cell membrane and the cell shape, as it is an intrinsic volume scanning technique. The multiphoton image formation bases on the detection of autofluorescence due to endogenous fluorophores. The nonlinearity of two-photon absorption provides submicron lateral and axial resolution without the need of confocal optical detection. In addition, in the near-IR cell damages are drastically reduced in comparison with direct excitation in the visible or UV. The presented setup was aligned with a dedicated procedure to ensure identical image areas. Combined multiphoton/acoustic images of living myoblast cells are discussed focusing on the reliability of the method. PMID:17380494

  20. 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, E-mail: tqjia@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Chen, Ping; Qiu, Jianrong [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    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.

  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. Multiphoton Dissociation of Electrosprayed MegaDalton-Sized DNA Ions in a Charge-Detection Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Doussineau, Tristan; Paletto, Pierre; Dugourd, Philippe; Antoine, Rodolphe

    2015-01-01

    Charge detection mass spectrometry in combination with a linear electrostatic ion trap coupled to a continuous wavelength infrared CO2 laser has been used to study the multiphoton dissociation of DNA macromolecular ions. Samples, with masses ranging from 2.23 to 31.5 MDa, include single strand circular M13mp18, double strand circular M13mp18, and double strand linear LambdaPhage DNA fragments. Their activation energies for unimolecular dissociation were determined. Activation energy values slightly increase as a function of the molecular weight. The most important result is the difference between the fragmentations observed for hybridized double-strands and dimers of single strands.

  3. Chronic imaging of amyloid plaques in the live mouse brain using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Bacskai, Brian J.; Kajdasz, Stephen T.; Christie, R. H.; Zipfel, Warren R.; Williams, Rebecca M.; Kasischke, Karl A.; Webb, Watt W.; Hyman, B. T.

    2001-04-01

    Transgenic mice expressing the human Amyloid Precursor Protein (APP) develop amyloid plaques as they age. These plaques resemble those found in the human disease. Multiphoton laser scanning microscopy combined with a novel surgical approach was used to measure amyloid plaque dynamics chronically in the cortex of living transgenic mice. Thioflavine S (thioS) was used as a fluorescent marker of amyloid deposits. Multiphoton excitation allowed visualization of amyloid plaques up to 200 micrometers deep into the brain. The surgical site could be imaged repeatedly without overt damage to the tissue, and individual plaques within this volume could be reliably identified over periods of several days to several months. On average, plaque sizes remained constant over time, supporting a model of rapid deposition, followed by relative stability. Alternative reporters for in vivo histology include thiazine red, and FITC-labeled amyloid-(Beta) peptide. We also present examples of multi-color imaging using Hoechst dyes and FITC-labeled tomato lectin. These approaches allow us to observe cell nuclei or microglia simultaneously with amyloid-(Beta) deposits in vivo. Chronic imaging of a variety of reporters in these transgenic mice should provide insight into the dynamics of amyloid-(Beta) activity in the brain.

  4. 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.

  5. Spectrally Resolved Multiphoton Imaging of In Vivo and Excised Mouse Skin Tissues

    PubMed Central

    Palero, Jonathan A.; de Bruijn, Henriëtte S.; van der Ploeg van den Heuvel, Angélique; Sterenborg, Henricus J. C. M.; Gerritsen, Hans C.

    2007-01-01

    The deep tissue penetration and submicron spatial resolution of multiphoton microscopy and the high detection efficiency and nanometer spectral resolution of a spectrograph were utilized to record spectral images of the intrinsic emission of mouse skin tissues. Autofluorescence from both cellular and extracellular structures, second-harmonic signal from collagen, and a narrowband emission related to Raman scattering of collagen were detected. Visualization of the spectral images by wavelength-to-RGB color image conversion allowed us to identify and discriminate tissue structures such as epidermal keratinocytes, lipid-rich corneocytes, intercellular structures, hair follicles, collagen, elastin, and dermal cells. Our results also showed morphological and spectral differences between excised tissue section, thick excised tissue, and in vivo tissue samples of mouse skin. Results on collagen excitation at different wavelengths suggested that the origin of the narrowband emission was collagen Raman peaks. Moreover, the oscillating spectral dependency of the collagen second-harmonic intensity was experimentally studied. Overall, spectral imaging provided a wealth of information not easily obtainable with present conventional multiphoton imaging systems. PMID:17449667

  6. In Vivo Multiphoton NADH Fluorescence Reveals Depth-Dependent Keratinocyte Metabolism in Human Skin

    PubMed Central

    Balu, Mihaela; Mazhar, Amaan; Hayakawa, Carole K.; Mittal, Richa; Krasieva, Tatiana B.; König, Karsten; Venugopalan, Vasan; Tromberg, Bruce J.

    2013-01-01

    We employ a clinical multiphoton microscope to monitor in vivo and noninvasively the changes in reduced nicotinamide adenine dinucleotide (NADH) fluorescence of human epidermal cells during arterial occlusion. We correlate these results with measurements of tissue oxy- and deoxyhemoglobin concentration during oxygen deprivation using spatial frequency domain imaging. During arterial occlusion, a decrease in oxyhemoglobin corresponds to an increase in NADH fluorescence in the basal epidermal cells, implying a reduction in basal cell oxidative phosphorylation. The ischemia-induced oxygen deprivation is associated with a strong increase in NADH fluorescence of keratinocytes in layers close to the stratum basale, whereas keratinocytes from epidermal layers closer to the skin surface are not affected. Spatial frequency domain imaging optical property measurements, combined with a multilayer Monte Carlo-based radiative transport model of multiphoton microscopy signal collection in skin, establish that localized tissue optical property changes during occlusion do not impact the observed NADH signal increase. This outcome supports the hypothesis that the vascular contribution to the basal layer oxygen supply is significant and these cells engage in oxidative metabolism. Keratinocytes in the more superficial stratum granulosum are either supplied by atmospheric oxygen or are functionally anaerobic. Based on combined hemodynamic and two-photon excited fluorescence data, the oxygen consumption rate in the stratum basale is estimated to be ?0.035 ?moles/106 cells/h. PMID:23332078

  7. Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

    PubMed Central

    Wokosin, David L.; Squirrell, Jayne M.; Eliceiri, Kevin W.; White, John G.

    2008-01-01

    Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components. PMID:18607511

  8. 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, E-mail: agust@hi.is [Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík (Iceland)

    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.

  9. Photoionization dynamics of excited molecular states

    NASA Astrophysics Data System (ADS)

    Dehmer, J. L.; Ohalloran, M. A.; Tomkins, F. S.; Dehmer, P. M.; Pratt, S. T.

    Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of opportunities for exploring excited state physics and chemistry at the quantum-state-specific level. Here we will first give a brief overview of the large variety of experimental approaches to excited state phenomena made possible by REMPI. Then we will examine in more detail, recent studies of the three photon resonant, four photon (3 + 1) ionization of H sub 2 via the C(I) sub pi sub u state. Strong non-Franck-Condon behavior in the photoelectron spectra of this nominally simple Rydberg state has led to the examination of a variety of dynamical mechanisms. Of these, the role of doubly excited autoionizing states now seems decisive. Progress on photoelectron studies of autoionizing states in H sub 2 , excited in a (2 + 1) REMPI process via the E,F(I) sub sigma plus sub g will also be briefly discussed.

  10. Imaging wound healing using optical coherence tomography and multiphoton microscopy in an in vitro

    E-print Network

    Chen, Zhongping

    -Optical Instrumentation Engineers. [DOI: 10.1117/1.1648646] Keywords: optical coherence tomography; multiphoton microscopyImaging wound healing using optical coherence tomography and multiphoton microscopy in an in vitro using opti- cal coherence tomography (OCT), multiphoton microscopy (MPM), and histopathology

  11. 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

  12. Maximizing fluorescence collection efficiency in multiphoton microscopy

    E-print Network

    Levene, Michael J.

    -photon fluorescence excitation in turbid media," Opt. Commun. 188(1­4), 25­29 (2001). 5. P. Theer, M. T. Hasan, and W. Imaging performance was verified by imaging layer V neurons in mouse cortex to a depth of 850 µm. ©2011 longer wavelength excitation," Opt. Express 17(16), 13354­13364 (2009). 10. S. G. Parra, T. H. Chia, J. P

  13. 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.

  14. Soliton dynamics in the multiphoton plasma regime

    NASA Astrophysics Data System (ADS)

    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.

  15. In vivo detection of cryosurgery using multiphoton and harmonic generation microscopy.

    PubMed

    Chen, Te-Hsuen; Huang, Chi-Jer Charles; Huang, Yi-You

    2008-10-01

    The tissue injury and the organization of collagen during cryosurgery are poorly characterized because of the lack of appropriate methodologies. In this study, we use multimodal multiphoton microscopy to assess the change of extracellular matrix after cryotreatment of skin. The cellular matrix transformations and the intercellular interactions during the wound healing process after cryolesion for mice were measured in vivo and in real-time through the dorsal skinfold chamber (DSC). Intrinsic second-harmonic generation (SHG) signals from fibrillar collagen and two-photon excited (TPE) autofluorescence from cell were collected to investigate the cryosurgical response in vivo. The TPE and SHG signals are significantly different between normal and cryotreated mice, and correlates with the wound healing process. The results suggest that this approach may be applied in real-time to noninvasively monitor the cryosurgery process and could potentially be applied to clinical evaluation. PMID:18378485

  16. 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.

  17. Evaluation of multiphoton effects in down-conversion

    SciTech Connect

    Yoshimi, Kazuyoshi [College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827 (Japan); Koshino, Kazuki [College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827 (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    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.

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

    SciTech Connect

    Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M., E-mail: m.h.m.janssen@vu.nl [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)] [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Powis, Ivan [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    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.

  19. Sub-Cycle Dynamics of High Harmonic Generation of He Atoms Excited by Attosecond Pulses and Driven by Near-Infrared Laser Fields: A Self-Interaction-Free TDDFT Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

    2014-05-01

    In the framework of the self-interaction-free time-dependent density functional theory, we have performed 3D ab initio calculations of He atoms in near-infrared (NIR) laser fields subject to excitation by a single extreme ultraviolet (XUV) attosecond pulse (SAP). We have explored the novel dynamical behavior of the sub-cycle high harmonic generation (HHG) for transitions from the excited states to the ground state and found oscillation structures with respect to the time delay between the SAP and NIR fields. The oscillatory pattern in the photon emission spectra has a period of 1.3 fs which is half of the NIR laser optical cycle, similar to that recently measured in the experiments on transient absorption of He. We present the photon emission spectra from 1s2p, 1s3p, 1s4p, 1s5p, and 1s6p excited states as functions of the time delay. We explore the sub-cycle Stark shift phenomenon in NIR fields and its influence on the photon emission process. Our analysis reveals several new features of the sub-cycle HHG dynamics and we identify the mechanisms responsible for the observed peak splitting in the photon emission spectra. This work was partially supported by DOE.

  20. 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. [Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States)

    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.

  1. 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.

  2. 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

  3. Optical clearing and multiphoton imaging of paraffin-embedded specimens

    NASA Astrophysics Data System (ADS)

    Wilson, Jesse W.; Degan, Simone; Fischer, Martin C.; Warren, Warren S.

    2013-02-01

    New labeling, imaging, or analysis tools could provide new retrospective insights when applied to archived, paraffin-embedded samples. Deep-tissue multiphoton microscopy of paraffin-embedded specimens is achieved using optical clearing with mineral oil. We tested a variety of murine tissue specimens including skin, lung, spleen, kidney, and heart, acquiring multiphoton autofluorescence and second-harmonic generation, and pump-probe images This technique introduces the capability for non-destructive 3-dimensional microscopic imaging of existing archived pathology specimens, enabling retrospective studies.

  4. MULTIPHOTON PROCESSES IN ISOLATED ATOMS AND MOLECULES

    E-print Network

    Sudbo, A.S.

    2010-01-01

    alkali atom with hyperfine struc­ For a square pulse of laseralkali atom excited on the D resonance line by a CW "single frequency" laser.alkali atom. The latter case can be treated in greater detail if the laser

  5. Pinpointing the extent of electronic delocalization in the Re(I)-to-tetrazine charge-separated excited state using time-resolved infrared spectroscopy.

    PubMed

    Li, Guifeng; Parimal, Kumar; Vyas, Shubham; Hadad, Christopher M; Flood, Amar H; Glusac, Ksenija D

    2009-08-26

    Femtosecond mid-IR transient absorption spectroscopy (TRIR) and time-dependent density functional theory (TD-DFT) calculations on Re(CO)(3)Cl(Me(2)BPTZ) [Me(2)BPTZ = 3,6-bis(5-methyl-2-pyridine)-1,2,4,5-tetrazine] are used to demonstrate that the lowest excited state of the complex is a triplet metal-to-ligand charge-transfer ((3)MLCT) state with a lifetime of 225 ps. The short excited-state lifetime is explained by the energy-gap law. Vibrational cooling of the (3)MLCT state shows up as early-time dynamics (3.6 ps). The structural changes in the excited state are deduced from the frequency shifts in the TRIR vibrational bands. The vibrational frequencies of the CO groups increase upon excitation as a result of decreased back-bonding between the CO ligands and the oxidized Re center in the (3)MLCT state. The vibrational frequencies of the central tetrazine ring of Me(2)BPTZ decrease because of the decrease in the bond order upon reduction of the Me(2)BPTZ ligand in the (3)MLCT state. Interestingly, the TRIR signals from the pyridine moieties of Me(2)BPTZ were not detected. These results can be explained by localization of the electronic charge on the central tetrazine ring in the (3)MLCT state of Re(CO)(3)Cl(Me(2)BPTZ), as supported by TD-DFT calculations. PMID:19653686

  6. Peak-power dependence of rovibronic populations below the quasicontinuum during IR multiphoton absorption

    SciTech Connect

    Brenner, D M

    1981-01-01

    Experimental studies on IR multiphoton absorption and dissociation have generally provided insight only into the relationship of IR laser characteristics such as power, wavelength, and mode structure to the observables dissociation yields, average number of photons absorbed, and product energy distribution. As a result, theoretical modeling of absorption at levels below the quasicontinuum has been based on facts somewhat removed from the actual phenomenon of interest. The experiments presented here provide information on the unperturbed rotational/vibrational populations of levels subsequent to IR excitation at levels below 4000 cm/sup -1/ of energy. The experiment makes use of molecular beam techniques in conjunction with IR-visible double resonance. A CO/sub 2/ laser of known pulse duration prepares vibrationally excited thiophosgene, Cl/sub 2/C = S. The absorbing transition is 2 ..nu../sub 4/. A tunable nitrogen-pumped dye laser scans the visible excitation spectrum to probe the perturbed rotational-vibrational populations of the pumped mode. Because the electronic transition is electric dipole forbidden, combination hot bands having the appropriate quantum numbers of the ground state are used in the analysis.

  7. Detecting the imaging characteristics of colorectal carcinoma invading the muscularis propria with multiphoton microscopy Detecting the imaging characteristics of colorectal carcinoma

    NASA Astrophysics Data System (ADS)

    Liu, N. R.; Chen, J. X.; Chen, G.; Yan, J.; Zhuo, S. M.; Jiang, X. S.

    2012-02-01

    The aim of this study was to examine the characteristics of the muscularis propria (mp) of human colorectum tissue with carcinoma invasion and help to advance the development for the diagnosis and therapy of early colorectal cancer. Multiphoton microscopic imaging system was used to achieve two-photon excited fluorescence (TPEF) and the second harmonic generation (SHG) images of samples respectively through the two-channel model. This work demonstrates the use of multiphoton microscopy (MPM) in obtaining clear images from thick layers of label-free tissues. Combined with endoscopy and miniaturization probes will be helpful for representing new methods to assess the functional behaviors of tissue and diagnose the early colorectal cancer in vivo.

  8. Monitoring UF/sub 6/ photodissociation via laser multiphoton ionization

    SciTech Connect

    Stuke, M.; Reisler, H.; Wittig, C.

    1981-08-01

    Laser multiphoton ionization (MPI) is used to detect nascent photoproducts following the UV photodissociation of UF/sub 6/. Sensitivity is high, and there is no measurable background due to the MPI of parent UF/sub 6/. The technique is very well suited for monitoring isotopically selective photodissociation on a ''single shot'' basis.

  9. Multiphoton Microscopy of Live Tissues With Ultraviolet Autofluorescence

    Microsoft Academic Search

    Chunqiang Li; Costas Pitsillides; Judith M. Runnels; Daniel Cote; Charles P. Lin

    2010-01-01

    Current research on multiphoton autofluorescence microscopy is primarily focused on imaging the signal from reduced nicotinamide adenine dinucleatide (NADH) in tissue. NADH levels in cells are useful reporters of metabolic information, as well as early indicators in precancer and cancer diagnosis. While NADH is typically imaged in the 400-500 nm spectral window, the amino acid tryptophan is the major source

  10. Advances in time-dependent methods for multiphoton processes

    SciTech Connect

    Kulander, K.C.; Schafer, K.J.; Krause, J.L.

    1990-09-01

    This paper discusses recent theoretical results on above threshold ionization harmonic generation and high-frequency, high intensity suppression of ionization. These studies of multiphoton processes in atoms and molecules for short, intense pulsed optical lasers have been carried out using techniques which involve the explicit solution of the time-dependent Schroedinger equation. 43 refs., 5 figs.

  11. 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

  12. A multiphoton microscope platform for imaging the mouse eye

    PubMed Central

    Masihzadeh, Omid; Lei, Tim C.; Ammar, David A.; Kahook, Malik Y.

    2012-01-01

    Purpose To demonstrate the ability of multiphoton microscopy to obtain full three-dimensional high-resolution images of the intact mouse eye anterior chamber without need for enucleation. Methods A custom multiphoton microscope was constructed and optimized for deep tissue imaging. Simultaneous two-photon autofluorescence (2PAF) and second harmonic generation (SHG) imaging were performed. A mouse holder and stereotaxic platform were designed to access different parts of the eye for imaging. A reservoir for keeping the eye moist was used during imaging sessions. Results Non-invasive multiphoton images deep inside the anterior chamber of the mouse eye were obtained without the need for enucleation. The iris, corneal epithelium and endothelium, trabecular meshwork region and conjunctiva were visualized by the 2PAF and SHG signals. Identification of the anatomy was achieved by the intrinsic properties of the native tissue without any exogenous labeling. Images as deep as 600 microns into the eye were clearly demonstrated. Full three-dimensional image reconstructions of the entire anterior chamber were performed and analyzed using custom software. Conclusions Multiphoton imaging is a highly promising tool for ophthalmic research. We have demonstrated the ability to image the entire anterior chamber of the mouse eye in its native state. These results provide a foundation for future in vivo studies of the eye. PMID:22815637

  13. Multiphoton multimode polarization entanglement in parametric down-conversion

    Microsoft Academic Search

    A. Gatti; R. Zambrini; M. San Miguel; L. A. Lugiato

    2003-01-01

    We study the quantum properties of the polarization of the light produced in type-II spontaneous parametric down-conversion in the framework of a multimode model valid in any gain regime. We show that the microscopic polarization entanglement of photon pairs survives in the high gain regime (multiphoton regime), in the form of nonclassical correlation of all the Stokes operators describing polarization

  14. Multiphoton ionization photoelectron spectroscopy of acetaldehyde via the A~ 1

    E-print Network

    Anderson, Scott L.

    Multiphoton ionization photoelectron spectroscopy of acetaldehyde via the A~ 1 A , B~ , C~ , and D spectra are reported for the acetaldehyde A~ 1 A , B~, C~ , and D~ states. Photoelectron spectroscopy spectrum of acetaldehyde was studied from the early 1940s by several groups.15­19 In those experiments

  15. MULTISCALE INTENSITY ESTIMATION FOR MULTI-PHOTON MICROSCOPY Rebecca Willett

    E-print Network

    Willett, Rebecca

    emissions resulting from fluorescence events occurring at each raster scan location. Each observed photon is detected along with auxiliary information such as its characteristic emission spectrum. The small number, Multidimensional signal processing 1. MULTI-PHOTON MICROSCOPY Fluorescence microscopy is widely used to generate

  16. Jet cooled spectra of pyrrolobenzene and of pyrrolobenzonitrile: the nature of the excited states

    E-print Network

    Haas, Yehuda

    multiphoton ionization (REMPI) excitation spectra of pyr- rolobenzene (PB) and pyrrolobenzonitrile (PBN) were.V. All rights reserved. 1. Introduction PB [1,2] and PBN [3,4] were recently studied in liquid solution) action spectra. In addition, fluo- rescence decay times were obtained. The results on PBN are compared

  17. Pulse-width considerations for multiple-photon excitation laser scanning fluorescence imaging

    Microsoft Academic Search

    David L. Wokosin; John G. White; Michael Dymott

    1998-01-01

    Fluorescence microscopy is a ubiquitous and powerful tool for the biologist mainly due to the availability of a wealth of highly specific fluorescent probes. Multiphoton (two or more photon) excitation fluorescence microscopy is an optical sectioning technique that offers significant advantages over other optical sectioning techniques in terms of improved viability of living material and the ability to penetrate deeper

  18. Rotational spectroscopy of the first excited state of the acetylenic C H stretch of 3-fluoropropyne performed by infrared-Fourier transform microwave microwave triple-resonance spectroscopy

    Microsoft Academic Search

    Kevin O. Douglass; Frances S. Rees; Richard D. Suenram; Brooks H. Pate; Igor Leonov

    2005-01-01

    The rotational spectra of 3-fluoropropyne in the ground and first excited acetylenic C H stretch vibrational state have been measured. The pure rotational spectrum of the normal species and the 13C isotopomers were measured using FTMW-cwMW double-resonance spectroscopy based on the Autler Townes (AC Stark) effect. The lineshape properties of this measurement make it possible to determine the transition strength,

  19. 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 ...

  20. Novel techniques with multiphoton microscopy: Deep-brain imaging with microprisms, neurometabolism of epilepsy, and counterfeit paper money detection

    NASA Astrophysics Data System (ADS)

    Chia, Thomas H.

    Multiphoton microscopy is a laser-scanning fluorescence imaging method with extraordinary potential. We describe three innovative multiphoton microscopy techniques across various disciplines. Traditional in vivo fluorescence microscopy of the mammalian brain has a limited penetration depth (<400 microm). We present a method of imaging 1 mm deep into mouse neocortex by using a glass microprism to relay the excitation and emission light. This technique enables simultaneous imaging of multiple cortical layers, including layer V, at an angle typical of slice preparations. At high-magnification imaging using an objective with 1-mm of coverglass correction, resolution was sufficient to resolve dendritic spines on layer V GFP neurons. Functional imaging of blood flow at various neocortical depths is also presented, allowing for quantification of red blood cell flux and velocity. Multiphoton fluorescence lifetime imaging (FLIM) of NADH reveals information on neurometabolism. NADH, an intrinsic fluorescent molecule and ubiquitous metabolic coenzyme, has a lifetime dependent on enzymatic binding. A novel NADH FLIM algorithm is presented that produces images showing spatially distinct NADH fluorescence lifetimes in mammalian brain slices. This program provides advantages over traditional FLIM processing of multi-component lifetime data. We applied this technique to a GFP-GFAP pilocarpine mouse model of temporal lobe epilepsy. Results indicated significant changes in the neurometabolism of astrocytes and neuropil in the cell and dendritic layers of the hippocampus when compared to control tissue. Data obtained with NADH FLIM were subsequently interpreted based on the abnormal activity reported in epileptic tissue. Genuine U.S. Federal Reserve Notes have a consistent, two-component intrinsic fluorescence lifetime. This allows for detection of counterfeit paper money because of its significant differences in fluorescence lifetime when compared to genuine paper money. We used scanning multiphoton laser excitation to sample a ˜4 mm2 region from 54 genuine Reserve Notes. Three types of counterfeit samples were tested. Four out of the nine counterfeit samples fit to a one-component decay. Five out of nine counterfeit samples fit to a two-component model, but are identified as counterfeit due to significant deviations in the longer lifetime component compared to genuine bills.

  1. Multi-photon induced ultraviolet emission from hexagram-shaped ZnO nanorods

    Microsoft Academic Search

    G. P. Zhu; J. Zhu; C. X. Xu; X. Li; J. P. Liu; Y. P. Cui

    2009-01-01

    Zinc oxide (ZnO) nanorods with hexagram cross-section were prepared by vapor-phase transport method. The growth mechanism\\u000a of the nanorods was discussed by considering diffusion effects of reactant gasses at high supersaturation. A strong ultraviolet\\u000a peak at 391 nm and a weak visible band depending on the excitation wavelength were observed under the excitation by infrared\\u000a femtosecond laser. The UV and

  2. Spectroscopic probes of vibrationally excited molecules at chemically significant energies. Progress report, August 15, 1991--August 14, 1992

    SciTech Connect

    Rizzo, T.R.

    1992-03-01

    These experiments apply multiple-laser spectroscopic techniques to investigate the bond energies, potential surface topologies, and dissociation dynamics of highly vibrationally excited molecules. Infrared-optical double resonance pumping of light atom stretch vibrations in H{sub 2}O{sub 2} and HN{sub 3} prepares reactant molecules in single rovibrational states above the unimolecular dissociation threshold on the ground potential surface, and laser induced fluorescence detection of the OH or NH fragments monitors the partitioning of energy into individual product quantum states. Product energy partitioning data from H{sub 2}O{sub 2} dissociation provide a stringent test of statistical theories as well as potential energy surface calculations. Ongoing work on HN{sub 3} seeks to determine the height of the barrier to dissociation on the singlet potential energy surface. Our most recently developed spectroscopic scheme allows the measurement of high vibrational overtone spectra of jet-cooled molecules. This approach uses CO{sub 2} laser infrared multiphoton dissociation followed by laser induced fluorescence product detection to measure weak vibrational overtone transitions in low pressure environments. Application of this scheme to record the {Delta}V{sub OH}=4 and {Delta}V{sub OH}=5 transitions of CH{sub 3}OH cooled in a supersonic free-jet demonstrates both its feasibility and its utility for simplifying high vibrational overtone spectra.

  3. Molecular Dynamics in Living Cells Observed by Fluorescence Correlation Spectroscopy with One and Two-Photon Excitation

    Microsoft Academic Search

    Petra Schwille; Ulrich Haupts; Sudipta Maiti; Watt W. Webb

    1999-01-01

    Multiphoton excitation (MPE) of fluorescent probes has become an attractive alternative in biological applications of laser scanning microscopy because many problems encountered in spectroscopic measurements of living tissue such as light scattering, autofluorescence, and photodamage can be reduced. The present study investigates the characteristics of two-photon excitation (2PE) in comparison with confocal one-photon excitation (1PE) for intracellular applications of fluorescence

  4. Herschel Far-Infrared Spectral-mapping of Orion BN/KL Outflows: Spatial distribution of excited CO, H2O, OH, O and C+ in shocked gas

    E-print Network

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

    2014-01-01

    We present ~2'x2' spectral-maps of Orion 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 ~54-310um 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)~5x10^{-3} ratio and a plethora of far-IR H2O emission lines. The high-J CO and OH lines are a factor ~2 brighter toward Peak 1 whereas several excited H2O lines are ~50% brighter toward Peak 2. A simplified non-LTE model allowed us to constrain the dominant gas temperature components. Most of the CO column density arises from Tk~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~10^{-2} abundance r...

  5. The role of resonances in strong-field multiphoton processes

    SciTech Connect

    Perry, M.D.; Kulander, K.C.

    1990-10-01

    Resonantly-enhanced multiphoton ionization (REMPI) has been the subject of extensive experimental and theoretical study since the invention of the laser. Until recently, the overwhelming majority of REMPI research have been conducted at intensities less than 10{sup 12} W/cm{sup 2}. At these intensities, the strength of the applied field remains less than one percent of the atomic Coulomb field experienced by the outer electrons in a typical noble gas atom. In this regime, treatment of the applied field as a weak perturbation on the atomic system yields excellent agreement with experiment. Here, we investigate the role of resonances in multiphoton ionization at much higher intensities, specifically, we examine the behavior and influence of resonances as the strength of the applied field becomes a significant fraction of the atomic field. 33 refs., 7 figs., 2 tabs.

  6. 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.

  7. Measurement-induced quantum operations on multiphoton states

    SciTech Connect

    Vitelli, Chiara; Spagnolo, Nicolo [Dipartimento di Fisica, Sapienza Universita di Roma, piazzale Aldo Moro 5, 00185 Roma (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, piazzale Aldo Moro 5, 00185 Roma (Italy); Sciarrino, Fabio [Dipartimento di Fisica, Sapienza Universita di Roma, piazzale Aldo Moro 5, 00185 Roma (Italy); Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (INO-CNR), largo E. Fermi 6, I-50125 Firenze (Italy); De Martini, Francesco [Dipartimento di Fisica, Sapienza Universita di Roma, piazzale Aldo Moro 5, 00185 Roma (Italy); Accademia Nazionale dei Lincei, via della Lungara 10, I-00165 Rome (Italy)

    2010-12-15

    We investigate how multiphoton quantum states obtained through optical parametric amplification can be manipulated by performing a measurement on a small portion of the output light field. We study in detail how the macroqubit features are modified by varying the amount of extracted information and the strategy adopted at the final measurement stage. At last the obtained results are employed to investigate the possibility of performing a microscopic-macroscopic nonlocality test free from auxiliary assumptions.

  8. Strong field Multiphoton processes in the high-frequency limit

    Microsoft Academic Search

    Gilles Doumy; Christoph Roedig; Anthony Dichiara; Cosmin Blaga; Louis Dimauro; Pierre Agostini; Matthias Hoener; Li Fang; Norrah Berrah; Linda Young; Elliot Kanter; Bertold Kraessig; Stephen Southworth; Robin Santra; Stephen Pratt; Phil Bucksbaum; James Cryan; James Glownia; Shambhu Ghimire; David Reis; Matthias Kuebel; Gerhard Paulus; John Bozek; Christoph Bostedt

    2010-01-01

    Last fall, the Linac Coherent Light Source at SLAC National Accelerator Laboratory has delivered users the world first X-ray free electron laser, allowing studying X-ray matter interaction at unprecedented photon flux. We will present the first attempts at observing multiphoton ionization in the X-ray regime, which have been realized by measuring both electron and ion spectra from the ionization of

  9. 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.

  10. Photochemical Synthesis and Multiphoton Luminescence of Monodisperse Silver Nanocrystals

    Microsoft Academic Search

    Thomas Kempa; Richard A. Farrer; Michael Giersig; John T. Fourkas

    2006-01-01

    A rapid, photochemical solution-phase synthesis has been developed for the production of monodisperse, nanometer-sized silver\\u000a particles. The stabilizer used in the synthesis can be used to control the average diameter of the particles over a range\\u000a from 1 to 7 nm. The same reaction mixture can also be employed to deposit patterns of nanoparticles with a laser via multiphoton\\u000a absorption. The

  11. Quantum radiation reaction effects in multiphoton Compton scattering

    E-print Network

    A. Di Piazza; K. Z. Hatsagortsyan; C. H. Keitel

    2010-11-24

    Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify quantum radiation reaction with the multiple photon recoils experienced by the laser-driven electron due to consecutive incoherent photon emissions. After determining a quantum radiation dominated regime, we demonstrate how in this regime quantum signatures of radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.

  12. In vivo multiphoton imaging of obstructive cholestasis in mice

    NASA Astrophysics Data System (ADS)

    Li, Feng-Chieh; Lee, Yu Yang; Chiou, Ling-Ling; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2010-02-01

    Combining multiphoton microscopy with a newly designed hepatic imaging window, we acquired in vivo images of mice obstructive cholestasis. We observed that in mice with bile duct ligation, bile canaliculi failed to appear during the whole observation period over 100 minutes following carboxyfluorescein diacetate injection, whereas the fluorescence was retained much longer within sinusoids. Furthermore, the fluorescence intensities in sinusoids were persistently higher than in hepatocytes during the course.

  13. CAD-integrated system for automated multi-photon three-dimensional micro- and nano-fabrication

    NASA Astrophysics Data System (ADS)

    Divliansky, Ivan B.; Weaver, Gregory; Petrovich, Michael; Jabbour, Toufic; Seigneur, Hubert P.; Parnell-Lampen, Caleb; Thompson, Amy; Belfield, Kevin D.; Kuebler, Stephen M.

    2005-01-01

    Multi-photon three-dimensional micro-/nano-fabrication (3DM) is a powerful technique for creating complex 3D micro-scale structures of the type needed for micro-electromechanical systems (MEMS), micro-optics, and microfluidics. In 3DM high peak-power laser pulses are tightly focused into a medium which undergoes a physical or chemical change following multi-photon excitation at the focal point. Complex structures are generated by serial 3D-patterned exposure within the material volume. To further the application of 3DM to micro-component engineering, we are developing a fully automated and integrated 3DM system capable of creating complex cross-linked polymer structures based on patterns designed in a CAD environment. The system consists of four major components: (1) a femtosecond laser and opto-mechanical system; (2) 3-axis micro-positioner; (3) a computer-controlled fabrication interface; and (4) software for fabrication-path planning. The path-planning software generates a 3DM command sequence based on an object-design input file created using standard commercial CAD software. The 3DM system can be used for start-to-finish design and fabrication of waveguides, 3D photonic crystals, and other complex micro-structures. These results demonstrate a technological path for implementing 3DM as a tool for micro- and nano-optical component manufacture.

  14. N-H Stretching Excitations in Adenosine-Thymidine Base Pairs in Solution: Base Pair Geometries, Infrared Line Shapes and Ultrafast Vibrational Dynamics

    PubMed Central

    Greve, Christian; Preketes, Nicholas K.; Fidder, Henk; Costard, Rene; Koeppe, Benjamin; Heisler, Ismael A.; Mukamel, Shaul; Temps, Friedrich; Nibbering, Erik T. J.; Elsaesser, Thomas

    2013-01-01

    We explore the N-H stretching vibrations of adenosine-thymidine base pairs in chloroform solution with linear and nonlinear infrared spectroscopy. Based on estimates from NMR measurements and ab initio calculations, we conclude that adenosine and thymidine form hydrogen bonded base pairs in Watson-Crick, reverse Watson-Crick, Hoogsteen and reverse Hoogsteen configurations with similar probability. Steady-state concentration- and temperature dependent linear FT-IR studies, including H/D exchange experiments, reveal that these hydrogen-bonded base pairs have complex N-H/N-D stretching spectra with a multitude of spectral components. Nonlinear 2D-IR spectroscopic results, together with IR-pump-IR-probe measurements, as also corroborated by ab initio calculations, reveal that the number of N-H stretching transitions is larger than the total number of N-H stretching modes. This is explained by couplings to other modes, such as an underdamped low-frequency hydrogen-bond mode, and a Fermi resonance with NH2 bending overtone levels of the adenosine amino-group. Our results demonstrate that modeling based on local N-H stretching vibrations only is not sufficient and call for further refinement of the description of the N-H stretching manifolds of nucleic acid base pairs of adenosine and thymidine, incorporating a multitude of couplings with fingerprint and low-frequency modes. PMID:23234439

  15. Partial indistinguishability theory for multiphoton experiments in multiport devices

    NASA Astrophysics Data System (ADS)

    Shchesnovich, V. S.

    2015-01-01

    We generalize an approach for description of multiphoton experiments with multiport unitary linear optical devices, started in Phys. Rev. A 89, 022333 (2014), 10.1103/PhysRevA.89.022333 with single photons in mixed spectral states, to arbitrary (multiphoton) input and arbitrary photon detectors. We show that output probabilities are always given in terms of the matrix permanents of the Hadamard product of a matrix built from the network matrix and matrices built from the spectral state of photons and spectral sensitivities of detectors. Moreover, in the case of input with up to one photon per mode, the output probabilities are given by a sum (or integral) with each term being the absolute value squared of such a matrix permanent. We conjecture that, for an arbitrary multiphoton input, zero output probability of an output configuration is always the result of an exact cancellation of quantum transition amplitudes of completely indistinguishable photons (a subset of all input photons) and, moreover, is independent of coherence between only partially indistinguishable photons. The conjecture is supported by examples. Furthermore, we propose a measure of partial indistinguishability of photons which generalizes Mandel's observation, and find the law of degradation of quantum coherence in a realistic boson-sampling device with increase of the total number of photons and/or their "classicality parameter."

  16. 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 405nm. As a result, a molecular ion was observed as the major ion and fragmentation was suppressed at wavelengths longer than 345nm. Furthermore, the detection limit measured at 345nm was measured to be the subpicogram level. The organic compounds were extracted from a 2.19mg 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 345nm, and the target NPAHs, including 9-nitroanthracene and 1-nitropyrene, were detected, and their concentrations were determined to be 5 and 3pg/m(3), respectively. PMID:26048831

  17. Cryogenic exciter

    DOEpatents

    Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

    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.

  18. Near-infrared excited state dynamics of melanins: the effects of iron content, photo-damage, chemical oxidation, and aggregate size.

    PubMed

    Simpson, Mary Jane; Wilson, Jesse W; Robles, Francisco E; Dall, Christopher P; Glass, Keely; Simon, John D; Warren, Warren S

    2014-02-13

    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

  19. 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

  20. Two-dimensional band dispersion and momentum-resolved lifetime of the image-potential state on graphite studied by angle-resolved multiphoton photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazutoshi; Azuma, Junpei; Kamada, Masao

    2012-02-01

    We studied the image-potential state (IPS) on a highly oriented pyrolitic graphite surface by means of angle-resolved multiphoton photoemission spectroscopy. The free-electron-like dispersion of IPSs with n = 1, 2, and 3 is observed for the first time with high energy and momentum resolution. From the dependence of the spectral intensity on the excitation density and comparisons with the energy diagram, it is suggested that IPSs are populated by the k//-conserved transition from the ?-band and the indirect transition from the ?-band. The linear dependence of the intrinsic line width on the energy suggests a contribution of intraband relaxation within the IPS band.

  1. A multimodal multiphoton microscope for biological imaging

    NASA Astrophysics Data System (ADS)

    Mouras, Rabah; Downes, Andrew; Rischitor, Grigore; Mari, Meropi; Elfick, Alistair

    2010-02-01

    We report on the construction of a highly flexible system for advanced biological imaging, where all the following imaging techniques are integrated into the same microscope: Coherent anti-Stokes Raman scattering (CARS), two photon excitation fluorescence (TPEF), second harmonic generation (SGH), sum frequency generation (SFG), fluorescence lifetime imaging (FLIM) and differential interference contrast (DIC). The system employs a Nd:YVO4 laser as pump (7 ps, 1064 nm), and two tunable OPOs (6 ps, 700 - 1000 nm). Our microscope comprises a heater stage and perfusion cell for imaging of live cells, and features an atomic force microscope (AFM) which enables optical imaging at 10 nm resolution. Multimodal imaging of breast cancer cells and tissue will be demonstrated as well as imaging of anticancer drugs in living cells.

  2. Exciting flavored bound states

    NASA Astrophysics Data System (ADS)

    Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

    2014-10-01

    We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

  3. Design and implementation of fiber-based multiphoton endoscopy with microelectromechanical systems

    E-print Network

    Chen, Zhongping

    of Photo-Optical Instrumentation Engineers. DOI: 10.1117/1.3127203 Keywords: multiphoton microscopy MPM; published online May 11, 2009. 1 Introduction Multiphoton microscopy MPM is an important tool for high and microscope platforms. However, for in vivo imaging and clinical applications, a fiber-optic MPM endoscope

  4. Electron spectroscopy study of single and double multiphoton ionization of strontium by visible picosecond laser light

    E-print Network

    Paris-Sud XI, Université de

    795 Electron spectroscopy study of single and double multiphoton ionization of strontium by visible'ionisation multiphotonique simple et double du strontium par des impulsions picosecondes de 1011 à quelque 1012 W cm-2 initial un état excité de l'ion. Abstract. 2014 Multiphoton single and double ionization of strontium

  5. UNIT 12.10Detecting Protein-Protein Interactions In Vivo with FRET using Multiphoton

    E-print Network

    Lamond, Angus I.

    UNIT 12.10Detecting Protein-Protein Interactions In Vivo with FRET using Multiphoton Fluorescence in vivo based on the measurement of FRET using the multiphoton fluorescence lifetime imaging microscopy (FLIM) technique. By using the FLIM-FRET technique, the spatial organization and quantification

  6. Caught in the Act: Intravital Multiphoton Microscopy of Host-Pathogen Interactions

    PubMed Central

    Hickman, Heather D.; Bennink, Jack R.; Yewdell, Jonathan W.

    2009-01-01

    Intravital multiphoton microscopy provides a unique opportunity to discover and characterize biological phenomena in the natural context of living organisms. Here we provide an overview of multiphoton microscopy with particular attention to its application for studying host-pathogen interactions. PMID:19154984

  7. 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.

  8. Infrared Astronomy

    NSDL National Science Digital Library

    NASA's Infrared Processing and Analysis Center (IPAC) provides the Infrared Astronomy Website as one of its outreach programs. Infrared Astronomy, or "the detection and study of the infrared radiation (heat energy) emitted from objects in the Universe," is described and placed in context in the sections Discovery of Infrared, What is Infrared, Infrared Astronomy, Background, and the Infrared Universe. For current information, see the News & Discoveries, Active/ Future Projects, and Activities sections; past and current projects supported by IPAC are featured in the Infrared Gallery. The site targets a broad audience and is geared towards many learning levels.

  9. Optimization of multi-photon event discrimination levels using Poisson statistics.

    PubMed

    Soukka, Juri; Virkki, Arho; Hänninen, Pekka; Soini, Juhani

    2004-01-12

    In applications where random multi-photon events must be distinguishable from the background, detection of the signals must be based on either analog current measurement or photon counting and multi-level discrimination of single and multi-photon events. In this paper a novel method for optimizing photomultiplier (PMT) pulse discrimination levels in single- and multi-photon counting is demonstrated. This calibration method is based on detection of photon events in coincidence to short laser pulses. The procedure takes advantage of Poisson statistics of single- and mult-iphoton signals and it is applicable to automatic calibration of photon counting devices on production line. Results obtained with a channel photomultiplier (CPM) are shown. By use of three parallel discriminators and setting the discriminator levels according to the described method resulted in a linear response over wide range of random single- and multi-photon signals. PMID:19471514

  10. Infrared planar laser-induced fluorescence imaging and applications to imaging of carbon monoxide and carbon dioxide

    Microsoft Academic Search

    Brian James Kirby

    2001-01-01

    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

  11. Resonant IR multi-photon dissociation spectroscopy of a trapped and sympathetically cooled biomolecular ion species.

    PubMed

    Wellers, Ch; Borodin, A; Vasilyev, S; Offenberg, D; Schiller, S

    2011-11-14

    In this work we demonstrate vibrational spectroscopy of polyatomic ions that are trapped and sympathetically cooled by laser-cooled atomic ions. We use the protonated dipeptide tryptophan-alanine (HTyrAla(+)) as a model system, cooled by barium ions to less than 800 mK secular temperature. The spectroscopy is performed on the fundamental vibrational transition of a local vibrational mode at 2.74 ?m using a continuous-wave optical parametric oscillator (OPO). Resonant IR multi-photon dissociation spectroscopy (R-IRMPD) (without the use of a UV laser) generates charged molecular fragments, which are sympathetically cooled and trapped, and subsequently released from the trap and counted. We measured the cross section for R-IRMPD under conditions of low intensity, and found it to be approximately two orders smaller than the vibrational excitation cross section. The observed rotational bandwidth of the vibrational transition is larger than the one expected from the combined effects of 300 K black-body temperature, conformer-dependent line shifts, and intermolecular vibrational relaxation broadening (J. Stearns et al., J. Chem. Phys., 2007, 127, 154322-154327). This indicates that as the internal energy of the molecule grows, an increase of the rotational temperature of the molecular ions well above room temperature (up to on the order of 1000 K), and/or an appreciable shift of the vibrational transition frequency (approx. 6-8 cm(-1)) occurs. PMID:21971203

  12. Digital deconvolution filter derived from linear discriminant analysis and application for multiphoton fluorescence microscopy.

    PubMed

    Sullivan, Shane Z; Schmitt, Paul D; Muir, Ryan D; DeWalt, Emma L; Simpson, Garth J

    2014-04-01

    A digital filter derived from linear discriminant analysis (LDA) is developed for recovering impulse responses in photon counting from a high speed photodetector (rise time of ~1 ns) and applied to remove ringing distortions from impedance mismatch in multiphoton fluorescence microscopy. Training of the digital filter was achieved by defining temporally coincident and noncoincident transients and identifying the projection within filter-space that best separated the two classes. Once trained, data analysis by digital filtering can be performed quickly. Assessment of the reliability of the approach was performed through comparisons of simulated voltage transients, in which the ground truth results were known a priori. The LDA filter was also found to recover deconvolved impulses for single photon counting from highly distorted ringing waveforms from an impedance mismatched photomultiplier tube. The LDA filter was successful in removing these ringing distortions from two-photon excited fluorescence micrographs and through data simulations was found to extend the dynamic range of photon counting by approximately 3 orders of magnitude through minimization of detector paralysis. PMID:24559143

  13. Fibrillogenesis from nanosurfaces: multiphoton imaging and stereological analysis of collagen 3D self-assembly dynamics.

    PubMed

    Bancelin, Stéphane; Decencière, Etienne; Machairas, Vaïa; Albert, Claire; Coradin, Thibaud; Schanne-Klein, Marie-Claire; Aimé, Carole

    2014-09-21

    The assembly of proteins into fibrillar structures is an important process that concerns different biological contexts, including molecular medicine and functional biomaterials. Engineering of hybrid biomaterials can advantageously provide synergetic interactions of the biopolymers with an inorganic component to ensure specific supramolecular organization and dynamics. To this aim, we designed hybrid systems associating collagen and surface-functionalized silica particles and we built a new strategy to investigate fibrillogenesis processes in such multicomponents systems, working at the crossroads of chemistry, physics and mathematics. The self-assembly process was investigated by bimodal multiphoton imaging coupling second harmonic generation (SHG) and 2 photon excited fluorescence (2PEF). The in-depth spatial characterization of the system was further achieved using the three-dimensional analysis of the SHG/2PEF data via mathematical morphology processing. Quantitation of collagen distribution around particles offers strong evidence that the chemically induced confinement of the protein on the silica nanosurfaces has a key influence on the spatial extension of fibrillogenesis. This new approach is unique in the information it can provide on 3D dynamic hybrid systems and may be extended to other associations of fibrillar molecules with optically responsive nano-objects. PMID:25058449

  14. Optical tweezers and multiphoton microscopies integrated photonic tool for mechanical and biochemical cell processes studies

    NASA Astrophysics Data System (ADS)

    de Thomaz, A. A.; Faustino, W. M.; Fontes, A.; Fernandes, H. P.; Barjas-Castro, M. d. L.; Metze, K.; Giorgio, S.; Barbosa, L. C.; Cesar, C. L.

    2007-09-01

    The research in biomedical photonics is clearly evolving in the direction of the understanding of biological processes at the cell level. The spatial resolution to accomplish this task practically requires photonics tools. However, an integration of different photonic tools and a multimodal and functional approach will be necessary to access the mechanical and biochemical cell processes. This way we can observe mechanicaly triggered biochemical events or biochemicaly triggered mechanical events, or even observe simultaneously mechanical and biochemical events triggered by other means, e.g. electricaly. One great advantage of the photonic tools is its easiness for integration. Therefore, we developed such integrated tool by incorporating single and double Optical Tweezers with Confocal Single and Multiphoton Microscopies. This system can perform 2-photon excited fluorescence and Second Harmonic Generation microscopies together with optical manipulations. It also can acquire Fluorescence and SHG spectra of specific spots. Force, elasticity and viscosity measurements of stretched membranes can be followed by real time confocal microscopies. Also opticaly trapped living protozoas, such as leishmania amazonensis. Integration with CARS microscopy is under way. We will show several examples of the use of such integrated instrument and its potential to observe mechanical and biochemical processes at cell level.

  15. 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 [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Guo Linna; Zhang Feng; Wen Yan; Liu Bitao [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Huang Yan [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    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.

  16. Strong field Multiphoton processes in the high-frequency limit

    NASA Astrophysics Data System (ADS)

    Doumy, Gilles; Roedig, Christoph; Dichiara, Anthony; Blaga, Cosmin; Dimauro, Louis; Agostini, Pierre; Hoener, Matthias; Fang, Li; Berrah, Norrah; Young, Linda; Kanter, Elliot; Kraessig, Bertold; Southworth, Stephen; Santra, Robin; Pratt, Stephen; Coffee, Ryan; Bucksbaum, Phil; Cryan, James; Glownia, James; Ghimire, Shambhu; Reis, David; Kuebel, Matthias; Paulus, Gerhard; Bozek, John; Bostedt, Christoph

    2010-03-01

    Last fall, the Linac Coherent Light Source at SLAC National Accelerator Laboratory has delivered users the world first X-ray free electron laser, allowing studying X-ray matter interaction at unprecedented photon flux. We will present the first attempts at observing multiphoton ionization in the X-ray regime, which have been realized by measuring both electron and ion spectra from the ionization of rare gases in the AMO end station. In addition to gaining insight into this new regime, our experiments also participated towards the characterization of this new light source (intensity, harmonic content).

  17. Use of adaptive optics for improved multiphoton imaging

    NASA Astrophysics Data System (ADS)

    Girkin, John M.; Marsh, Paul N.

    2004-06-01

    We report on the integration of active optical elements in a multiphoton microscope to improve the resolution and overall image quality when imaging deeply into biological samples. Optical models were generated of sample systems and these have been compared with the performance of the complete imaging system. The active elements used were commercially available flexible membrane mirrors controlled by custom, home written, software. Significant improvements in image quality have been demonstrated using a range of optimisation routines based on the analysis of the images produced by the system, rather than with a wavefront sensor. A three-fold increase in the resolution 100?m into the sample was achieved.

  18. 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

  19. Statistics of multiphoton events in spontaneous parametric down-conversion

    E-print Network

    Wojciech Wasilewski; Czeslaw Radzewicz; Robert Frankowski; Konrad Banaszek

    2008-05-12

    We present an experimental characterization of the statistics of multiple photon pairs produced by spontaneous parametric down-conversion realized in a nonlinear medium pumped by high-energy ultrashort pulses from a regenerative amplifier. The photon number resolved measurement has been implemented with the help of a fiber loop detector. We introduce an effective theoretical description of the observed statistics based on parameters that can be assigned direct physical nterpretation. These parameters, determined for our source from the collected experimental data, characterize the usefulness of down-conversion sources in multiphoton interference schemes that underlie protocols for quantum information processing and communication.

  20. In vivo video rate multiphoton microscopy imaging of human skin

    NASA Astrophysics Data System (ADS)

    Lee, Anthony M. D.; Wang, Hequn; Yu, Yingqiu; Tang, Shuo; Zhao, Jianhua; Lui, Harvey; McLean, David I.; Zeng, Haishan

    2011-08-01

    We present a multiphoton microscopy instrument specially designed for in vivo dermatological use that is capable of imaging human skin at 27framespersecond with 256pixels×256pixels resolution without the use of exogenous contrast agents. Imaging at fast frame rates is critical to reducing image blurring due to patient motion and to providing practically short clinical measurement times. Second harmonic generation and two-photon fluorescence images and videos acquired at optimized wavelengths are presented showing cellular and tissue structures from the skin surface down to the reticular dermis.

  1. Multi-photon induced ultraviolet emission from hexagram-shaped ZnO nanorods

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    Zinc oxide (ZnO) nanorods with hexagram cross-section were prepared by vapor-phase transport method. The growth mechanism of the nanorods was discussed by considering diffusion effects of reactant gasses at high supersaturation. A strong ultraviolet peak at 391 nm and a weak visible band depending on the excitation wavelength were observed under the excitation by infrared femtosecond laser. The UV and the visible emission were respectively attributed to four-photon induced photoluminescence (FPPL) and third harmonic generation (THG). The characteristics and the generation mechanism of the FPPL were discussed.

  2. Multiphoton microscopy for tumor regression grading after neoadjuvant treatment for colorectal carcinoma

    PubMed Central

    Li, Lian-Huang; Chen, Zhi-Fen; Wang, Xing-Fu; Zhuo, Shuang-Mu; Li, Hong-Sheng; Jiang, Wei-Zhong; Guan, Guo-Xian; Chen, Jian-Xin

    2015-01-01

    AIM: To evaluate the feasibility of using multiphoton microscopy (MPM) to assess a tumor regression grading (TRG) system. METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radiochemotherapy at the Fujian Medical University Union Hospital were obtained immediately after proctectomy. Specimens were serially sectioned (10 µm thickness) and used for MPM or stained with hematoxylin and eosin for comparison. Sections were imaged by MPM using 810 nm excitation, and images were collected in two wavelength channels corresponding to second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals. The ratio of these signal intensities was used to distinguish fibrosis from normal mucosal and serosal tissues. RESULTS: TRG of specimens assessed by MPM were in complete agreement with histologic grading performed by a consulting pathologist. SHG and TPEF images clearly revealed collagen fibers and fragmented elastic fibers in the muscularis propria specimens following neoadjuvant radiochemotherapy. Additionally, blood vessel hyperplasia was observed as thickening and fibrosis of the intima and media, which was accompanied by minimal inflammatory cell infiltration. Furthermore, the SHG/TPEF ratio in stromal fibrosis (4.15 ± 0.58) was significantly higher than those in the normal submucosal (2.31 ± 0.52) and serosal (1.47 ± 0.10) tissues (P < 0.001 for both). Analysis of emission spectra from cancerous tumor cells revealed two peaks corresponding to nicotinamide adenine dinucleotide hydrogen and flavin adenine dinucleotide signals; the ratio of these values was 1.19 ± 0.02, which is close to a normal metabolic state. CONCLUSION: MPM can be used to perform real-time diagnosis of tumor response after neoadjuvant treatment, and can be applied to evaluate TRG. PMID:25892870

  3. Theoretical studies of electronically excited states

    SciTech Connect

    Besley, Nicholas A. [School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

    2014-10-06

    Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

  4. Mg in electromagnetic fields: Theoretical partial multiphoton cross sections

    SciTech Connect

    Nikolopoulos, L.A.A. [Department of Telecommunications Science and Technology, University of Peloponnese, 22 100 Tripolis (Greece)

    2005-03-01

    We present ab initio calculations of multiphoton ionization cross sections--up to four--in atomic magnesium. We have followed a configuration interaction approach with the basis set constructed in terms of L{sup 2} integrable B-spline polynomials. The multiphoton ionization cross sections are given for a range of photon energies where the ion is left in its ground state. For the two-photon ionization process we calculate the cross section as a function of the photon energy and compare with known theoretical results. We also provide the corresponding angular asymmetry parameters which determine the angular distribution of the ionized electron. We have extended the energy range of reported theoretical three-photon ionization cross section while we present the four-photon cross section in the region between the 3s and 3p ionization thresholds. In this region the 3p{sup 2} {sup 1}S autoionizing state is identified through the four-photon absorption process and the related four-photon Fano q parameter is obtained.

  5. The electronic origin and vibrational levels of the first excited singlet state of isocyanic acid (HNCO)

    NASA Astrophysics Data System (ADS)

    Berghout, H. Laine; Crim, F. Fleming; Zyrianov, Mikhail; Reisler, Hanna

    2000-04-01

    The combination of vibrationally mediated photofragment yield spectroscopy, which excites molecules prepared in single vibrational states, and multiphoton fluorescence spectroscopy, which excites molecules cooled in a supersonic expansion, provides detailed information on the energetics and vibrational structure of the first excited singlet state (S1) of isocyanic acid (HNCO). Dissociation of molecules prepared in individual vibrational states by stimulated Raman excitation probes vibrational levels near the origin of the electronically excited state. Detection of fluorescence from dissociation products formed by multiphoton excitation through S1 of molecules cooled in a supersonic expansion reveals the vibrational structure at higher energies. Both types of spectra show long, prominent progressions in the N-C-O bending vibration built on states with different amounts of N-C stretching excitation and H-N-C bending excitation. Analyzing the spectra locates the origin of the S1 state at 32 449±20 cm-1 and determines the harmonic vibrational frequencies of the N-C stretch (?3=1034±20 cm-1), the H-N-C bend (?4=1192±19 cm-1), and the N-C-O bend (?5=599±7 cm-1), values that are consistent with several ab initio calculations. The assigned spectra strongly suggest that the N-C stretching vibration is a promoting mode for internal conversion from S1 to S0.

  6. 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)

  7. Infrared Investigations

    NSDL National Science Digital Library

    2013-08-30

    In this activity, learners explore how infrared technology is used by engineers to create equipment and systems for a variety of industries. Learners explore the application of infrared in remote controls, test materials that encourage or prevent infrared transmission, and develop systems that allow transmission of infrared in restricted environments.

  8. Thermal excitation of multi-photon dressed states in circuit quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Fink, J. M.; Baur, M.; Bianchetti, R.; Filipp, S.; Göppl, M.; Leek, P. J.; Steffen, L.; Blais, A.; Wallraff, A.

    2009-12-01

    The exceptionally strong coupling realizable between superconducting qubits and photons stored in an on-chip microwave resonator allows for the detailed study of matter-light interactions in the realm of circuit quantum electrodynamics (QED). Here we investigate the resonant interaction between a single transmon-type multilevel artificial atom and weak thermal and coherent fields. We explore up to three photon dressed states of the coupled system in a linear response heterodyne transmission measurement. The results are in good quantitative agreement with a generalized Jaynes-Cummings model. Our data indicate that the role of thermal fields in resonant cavity QED can be studied in detail using superconducting circuits.

  9. Thermal Excitation of Multi-Photon Dressed States in Circuit Quantum Electrodynamics

    E-print Network

    Fink, J M; Bianchetti, R; Filipp, S; Göppl, M; Leek, P J; Steffen, L; Blais, A; Wallraff, A

    2009-01-01

    The exceptionally strong coupling realizable between superconducting qubits and photons stored in an on-chip microwave resonator allows for the detailed study of matter-light interactions in the realm of circuit quantum electrodynamics (QED). Here we investigate the resonant interaction between a single transmon-type multilevel artificial atom and weak thermal and coherent fields. We explore up to three photon dressed states of the coupled system in a linear response heterodyne transmission measurement. The results are in good quantitative agreement with a generalized Jaynes-Cummings model. Our data indicates that the role of thermal fields in resonant cavity QED can be studied in detail using superconducting circuits.

  10. Thermal Excitation of Multi-Photon Dressed States in Circuit Quantum Electrodynamics

    E-print Network

    J. M. Fink; M. Baur; R. Bianchetti; S. Filipp; M. Göppl; P. J. Leek; L. Steffen; A. Blais; A. Wallraff

    2009-11-19

    The exceptionally strong coupling realizable between superconducting qubits and photons stored in an on-chip microwave resonator allows for the detailed study of matter-light interactions in the realm of circuit quantum electrodynamics (QED). Here we investigate the resonant interaction between a single transmon-type multilevel artificial atom and weak thermal and coherent fields. We explore up to three photon dressed states of the coupled system in a linear response heterodyne transmission measurement. The results are in good quantitative agreement with a generalized Jaynes-Cummings model. Our data indicates that the role of thermal fields in resonant cavity QED can be studied in detail using superconducting circuits.

  11. Thermal Excitation of Multi-Photon Dressed States in Circuit Quantum Electrodynamics

    E-print Network

    Wallraff, Andreas

    in an on-chip microwave resonator allows for the detailed study of matter-light interactions in the realm photon dressed states of the coupled system in a linear response heterodyne transmission measurement] provides similar evidence for the quantization of microwave radiation in circuit QED. Further experimental

  12. Study of the formation and decay of KrXe* excimers at room temperature following selective excitation of the xenon 6s states

    Microsoft Academic Search

    G. Ledru; F. Marchal; N. Merbahi; J. P. Gardou; N. Sewraj

    2007-01-01

    The VUV emissions of gaseous mixtures of krypton and xenon were investigated at room temperature. For this purpose, a pulsed, brief, selective multiphotonic excitation of the two lowest atomic states of the 5p56s configuration of xenon was achieved. A spectroscopic and kinetic study was performed, for the first time, by comparing the radiation characteristics consecutive to initially populating either the

  13. 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.

  14. 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 ...

  15. Direct Observation of Multiphoton Processes in Laser-Induced Free-Free Transitions

    Microsoft Academic Search

    A. Weingartshofer; J. K. Holmes; G. Caudle; E. M. Clarke; H. Krueger

    1977-01-01

    Multiphoton processes are detected in the scattering of electrons on argon atoms in the presence of a strong CO2-laser field. The observations are in accordance with a recently developed semiclassical model.

  16. Multiphoton ionization of CF3I clusters by ultraviolet laser radiation

    NASA Astrophysics Data System (ADS)

    Apatin, V. M.; Lokhman, V. N.; Ogurok, D. D.; Poydashev, D. G.; Ryabov, E. A.

    2011-01-01

    The results of the investigation of the multiphoton ionization of (CF3I) n clusters by ultraviolet laser radiation are reported. The yields of the I{2/+} and I+ ions, which are the products of the multiphoton ionization, have been measured as functions of the intensity of the ultraviolet radiation at the wavelengths of 308 and 232.5 nm. The degree of multiphoton ionization has been determined and appears to depend on the wavelength of radiation. The velocity distributions of the products have been measured in detail for various wavelengths and various polarizations of radiation. The anisotropy parameters of the velocity distributions of the produced ions and their kinetic energy have been determined. After analysis of the data, a mechanism of the multiphoton ultraviolet ionization of the clusters under investigation has been proposed. This mechanism depends on the used wavelengths.

  17. 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 ...

  18. 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.

  19. 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.

  20. Watching stem cells at work with a flexible multiphoton tomograph

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Hoffmann, Robert; Weinigel, Martin; König, Karsten

    2012-03-01

    There is a high demand for non-invasive imaging techniques that allow observation of stem cells in their native environment without significant input on cell metabolism, reproduction, and behavior. Easy accessible hair follicle pluripotent stem cells in the bulge area and dermal papilla are potential sources for stem cell based therapy. It has been shown that these cells are able to generate hair, non-follicle skin cells, nerves, vessels, smooth muscles etc. and may participate in wound healing processes. We report on the finding of nestin-GFP expressing stem cells in their native niche in the bulge of the hair follicle of living mice by using high-resolution in-vivo multiphoton tomography. The 3D imaging with submicron resolution was based on two-photon induced fluorescence and second harmonic generation (SHG) of collagen. Migrating stem cells from the bulge to their microenvironment have been detected inside the skin during optical deep tissue sectioning.

  1. Multi-photon absorption limits to heralded single photon sources

    NASA Astrophysics Data System (ADS)

    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.

    2013-11-01

    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.

  2. Multi-photon absorption limits to heralded single photon sources.

    PubMed

    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

  3. 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

  4. Manipulating multi-photon entanglement in waveguide quantum circuits

    E-print Network

    Jonathan C. F. Matthews; Alberto Politi; Andre Stefanov; Jeremy L. O'Brien

    2009-11-06

    On-chip integrated photonic circuits are crucial to further progress towards quantum technologies and in the science of quantum optics. Here we report precise control of single photon states and multi-photon entanglement directly on-chip. We manipulate the state of path-encoded qubits using integrated optical phase control based on resistive elements, observing an interference contrast of 98.2+/-0.3%. We demonstrate integrated quantum metrology by observing interference fringes with 2- and 4-photon entangled states generated in a waveguide circuit, with respective interference contrasts of 97.2+/-0.4% and 92+/-4%, sufficient to beat the standard quantum limit. Finally, we demonstrate a reconfigurable circuit that continuously and accurately tunes the degree of quantum interference, yielding a maximum visibility of 98.2+/- 0.9%. These results open up adaptive and fully reconfigurable photonic quantum circuits not just for single photons, but for all quantum states of light.

  5. Multiphoton quantum interference in a multiport integrated photonic device.

    PubMed

    Metcalf, Benjamin J; Thomas-Peter, Nicholas; Spring, Justin B; Kundys, Dmytro; Broome, Matthew A; Humphreys, Peter C; Jin, Xian-Min; Barbieri, Marco; Kolthammer, W Steven; Gates, James C; Smith, Brian J; Langford, Nathan K; Smith, Peter G R; Walmsley, Ian A

    2013-01-01

    Increasing the complexity of quantum photonic devices is essential for many optical information processing applications to reach a regime beyond what can be classically simulated, and integrated photonics has emerged as a leading platform for achieving this. Here we demonstrate three-photon quantum operation of an integrated device containing three coupled interferometers, eight spatial modes and many classical and nonclassical interferences. This represents a critical advance over previous complexities and the first on-chip nonclassical interference with more than two photonic inputs. We introduce a new scheme to verify quantum behaviour, using classically characterised device elements and hierarchies of photon correlation functions. We accurately predict the device's quantum behaviour and show operation inconsistent with both classical and bi-separable quantum models. Such methods for verifying multiphoton quantum behaviour are vital for achieving increased circuit complexity. Our experiment paves the way for the next generation of integrated photonic quantum simulation and computing devices. PMID:23322044

  6. 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.

  7. Multiphoton ionization of transient species in supersonic jets

    SciTech Connect

    Miller, J.C.; Feigerle, C.S.

    1988-01-01

    A series of experiments utilizing mass-resolved multiphoton ionization to study NO diluted into supersonic beams of rare gases is presented. The sensitivity of the technique is demonstrated by the detection of 10/sup 3)-10/sup 4/ molecules of the rare isotopic combination /sup 15/N/sup 18/O in its natural abundance. New results are given on the spectroscopy and photophysics of the Ar-NO, Kr-NO, and Xe-NO van der Waals molecules present in the beam. Finally, the addition of an electron beam or glow discharge at the orifice of the supersonic nozzle results in the formation of metastable rare gas atoms, sputtered metal atoms, and vibrationally hot NO molecules. 18 refs., 4 figs.

  8. Live-Animal Imaging of Renal Function by Multiphoton Microscopy

    PubMed Central

    Dunn, Kenneth W.; Sutton, Timothy A.; Sandoval, Ruben M.

    2015-01-01

    Intravital microscopy, microscopy of living animals, is a powerful research technique that combines the resolution and sensitivity found in microscopic studies of cultured cells with the relevance and systemic influences of cells in the context of the intact animal. The power of intravital microscopy has recently been extended with the development of multiphoton fluorescence microscopy systems capable of collecting optical sections from deep within the kidney at subcellular resolution, supporting high-resolution characterizations of the structure and function of glomeruli, tubules, and vasculature in the living kidney. Fluorescent probes are administered to an anesthetized, surgically prepared animal, followed by image acquisition for up to 3 hr. Images are transferred via a high-speed network to specialized computer systems for digital image analysis. This general approach can be used with different combinations of fluorescent probes to evaluate processes such as glomerular permeability, proximal tubule endocytosis, microvascular flow, vascular permeability, mitochondrial function, and cellular apoptosis/necrosis. PMID:23042524

  9. Reassignment of Scattered Emission Photons in Multifocal Multiphoton Microscopy

    PubMed Central

    Cha, Jae Won; Singh, Vijay Raj; Kim, Ki Hean; Subramanian, Jaichandar; Peng, Qiwen; Yu, Hanry; Nedivi, Elly; So, Peter T. C.

    2014-01-01

    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 of image signal-to-noise-ratio (SNR) due to the scattering of emitted photons. SNR can be partly recovered using multianode photomultiplier tubes (MAPMT). In this design, however, emission photons scattered to neighbor anodes are encoded by the foci scan location resulting in ghost images. The crosstalk between different anodes is currently measured a priori, which is cumbersome as it depends specimen properties. Here, we present the photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, for quantification of crosstalk between the anodes of MAPMT without a priori measurement. The method provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image. PMID:24898470

  10. High-Resolution Multiphoton Imaging of Tumors In Vivo

    PubMed Central

    Wyckoff, Jeffrey; Gligorijevic, Bojana; Entenberg, David; Segall, Jeffrey; Condeelis, John

    2014-01-01

    Analysis of the individual steps in metastasis is crucial if insights at the molecular level are to be linked to the cell biology of cancer. A technical hurdle to achieving the analysis of the individual steps of metastasis is the fact that, at the gross level, tumors are heterogeneous in both animal models and patients. Human primary tumors show extensive variation in all properties ranging from growth and morphology of the tumor through tumor-cell density in the blood and formation and growth of metastases. Methods capable of the direct visualization and analysis of tumor-cell behavior at single-cell resolution in vivo have become crucial in advancing the understanding of mechanisms of metastasis, the definition of microenvironment, and the markers related to both. This article discusses the use of high-resolution multiphoton imaging of tumors (specifically breast tumors in mice) in vivo. PMID:21969629

  11. In vivo multiphoton imaging of bile duct ligation

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Li, Feng-Chieh; Chen, Hsiao-Chin; Chang, Po-shou; Yang, Shu-Mei; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2008-02-01

    Bile is the exocrine secretion of liver and synthesized by hepatocytes. It is drained into duodenum for the function of digestion or drained into gallbladder for of storage. Bile duct obstruction is a blockage in the tubes that carry bile to the gallbladder and small intestine. However, Bile duct ligation results in the changes of bile acids in serum, liver, urine, and feces1, 2. In this work, we demonstrate a novel technique to image this pathological condition by using a newly developed in vivo imaging system, which includes multiphoton microscopy and intravital hepatic imaging chamber. The images we acquired demonstrate the uptake, processing of 6-CFDA in hepatocytes and excretion of CF in the bile canaliculi. In addition to imaging, we can also measure kinetics of the green fluorescence intensity.

  12. Multiphoton gradient index endoscopy for evaluation of diseased human prostatic tissue ex vivo

    NASA Astrophysics Data System (ADS)

    Huland, David M.; Jain, Manu; Ouzounov, Dimitre G.; Robinson, Brian D.; Harya, Diana S.; Shevchuk, Maria M.; Singhal, Paras; Xu, Chris; Tewari, Ashutosh K.

    2014-11-01

    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.

  13. Complex effective Hamiltonian approach for ir multiphoton dissociation

    NASA Astrophysics Data System (ADS)

    Flosnik, Thomas M.; Wyatt, Robert E.

    1989-11-01

    A complex effective Hamiltonian (CEH) approach is formulated in the semiclassical (quantum-molecule-classical-field) representation for the study of ir multiphoton-dissociation processes. This formulation enables one to evaluate the dissociation dynamics in terms of the discrete states only. The effects of the bound-continuum-state interactions are manifested in the CEH matrix by the addition of level shifts and imaginary decay widths to the unperturbed bound-state energies and bound-bound dipole-coupling elements. The periodicity of the CEH matrix in time is preserved, allowing the use of Floquet theory to exactly evaluate the time development of the system. This CEH formulation requires that transitions between continuum states can be safely ignored, that the bound-continuum dipole couplings vary slowly with the continuum state energy ?, and that time t is sufficiently long. High field intensities also tend to make these requirements more stringent. It is found that the CEH matrix in the semiclassical representation can be asymmetric with respect to the level shifts and decay widths. For the ir multiphoton dissociation of a nonrotating model diatomic molecule in the ground electronic state, a rather truncated form of the CEH is tested against a discretized continuum plus optical potential method. Despite the high field intensity and relatively short laser pulse used in these tests, the results indicate that this CEH method works well provided the bound-continuum dipole-coupling elements vary slowly with ?. As can be expected, the validity of the CEH is limited when the bound-continuum dipole couplings vary strongly with ?, which is the case with our model diatomic molecule. The nature of the bound-continuum interactions can apparently have considerable effect on the dissociation dynamics.

  14. Quantum secure communication using a multi-photon tolerant protocol

    NASA Astrophysics Data System (ADS)

    El Rifai, Mayssaa; Verma, Pramode K.

    2015-03-01

    This paper proposes a quantum secure communication protocol using multiple photons to represent each bit of a message to be shared. The multi-photon tolerant approach to quantum cryptography provides a quantum level security while using more than a single photon per transmission. The protocol proposed is a multi-stage protocol; an explanation of its operation and implementation are provided. The multi-stage protocol is based on the use of unitary transformations known only to Alice and Bob. This paper studies the security aspects of the multi-stage protocol by assessing its vulnerability to different attacks. It is well known that as the number of photons increases, the level of vulnerability of the multi-stage protocol increases. This paper sets a limit on the number of photons that can be used while keeping the multi-stage protocol a multi-photon tolerant quantum secure method for communication. The analysis of the number of photons to be used is based on the probability of success of a Helstrom discrimination done by an eavesdropper on the channel. Limiting the number of photons up to certain threshold per stage makes it impossible for an eavesdropper to decipher the message sent over the channel. The proposed protocol obviates the disadvantages associated with single photon implementations, such as limited data rates and distances along with the need to have no more than a single photon per time slot. The multi-stage protocol is a step toward direct quantum communication rather than quantum key distribution associated with single photon approaches.

  15. Infrared-induced conformational isomerization and vibrational relaxation dynamics in melatonin and 5-methoxy-N-acetyl

    E-print Network

    Zwier, Timothy S.

    Infrared-induced conformational isomerization and vibrational relaxation dynamics in melatonin the infrared excitation early in a supersonic expansion, the excited molecules were re-cooled into their zero of the infrared excitation. In order to study the dependence of the isomerization on the cooling rate

  16. Fast XYT imaging of elementary calcium release events in muscle with multifocal multiphoton microscopy and wavelet denoising and detection.

    PubMed

    Von Wegner, Frederic; Both, Martin; Fink, Rainer H A; Friedrich, Oliver

    2007-07-01

    We used multifocal multiphoton microscopy to image fast, localized elevations of the cytosolic Ca2+ concentration in two spatial dimensions plus time (XYT). This technique extends the common spatially 1-D XT imaging and allows the acquisition of more than ten times longer time series (>500 images) and ten times larger areas of interest than for previously used confocal XYT imaging techniques due to lower phototoxicity and fast multifocal scanning. We recorded spontaneously occurring elementary Ca2+ release events in chemically permeabilized adult mammalian skeletal muscle fibers using two-photon excitation of the fluorescent dye Fluo-4. The resulting time series were analyzed with an automated denoising and detection algorithm based on the à trous implementation of the discrete wavelet transform. Wavelet coefficient hard-thresholding is used for denoising and event detection is performed across several wavelet scales. The spatiotemporal characteristics of the detected Ca2+ release events are followed throughout the XYT stack and are parametrized using a biophysically valid anisotropic Gaussian event model. The proposed method allows a detailed spatiotemporal analysis of elementary Ca2+ release events underlying the excitation-contraction coupling process in muscle. PMID:17649906

  17. Extragalactic infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Joseph, R. D.; Wright, G. S.; Wade, R.; Graham, J. R.; Gatley, I.; Prestwich, A. H.

    1987-01-01

    The spectra of galaxies in the near infrared atmospheric transmission windows are explored. Emission lines were detected due to molecular hydrogen, atomic hydrogen recombination lines, a line attributed to FEII, and a broad CO absorption feature. Lines due to H2 and FEII are especially strong in interacting and merging galaxies, but they were also detected in Seyferts and normal spirals. These lines appear to be shock excited. Multi-aperture measurements show that they emanate from regions as large as 15 kpc. It is argued that starbursts provide the most plausible and consistent model for the excitation of these lines, but the changes of relative line intensity of various species with aperture suggest that other excitation mechanisms are also operating in the outer regions of these galaxies.

  18. Reaction of Cl with CD{sub 4} excited to the second C-D stretching overtone

    SciTech Connect

    Martin, Marion R.; Ankeny Brown, Davida J.; Chiou, Albert S.; Zare, Richard N. [Department of Chemistry, Stanford University, Stanford, California 94305-5080 (United States)

    2007-01-28

    The effects of vibrational excitation on the Cl+CD{sub 4} reaction are investigated by preparing three nearly isoenergetic vibrational states: |3000> at 6279.66 cm{sup -1}, |2100> at 6534.20 cm{sup -1}, and |1110> at 6764.24 cm{sup -1}, where |D{sub 1}D{sub 2}D{sub 3}D{sub 4}> identifies the number of vibrational quanta in each C-D oscillator. Vibrational excitation of the perdeuteromethane is via direct infrared pumping. The reaction is initiated by photolysis of molecular chlorine at 355 nm. The nascent methyl radical product distribution is measured by 2+1 resonance-enhanced multiphoton ionization at 330 nm. The resulting CD{sub 3} state distributions reveal a preference to remove all energy available in the most excited C-D oscillator. Although the energetics are nearly identical, the authors observe strong mode specificity in which the CD{sub 3} state distributions markedly differ between the three Cl-atom reactions. Reaction with CD{sub 4} prepared in the |3000> mode leads to CD{sub 3} products populated primarily in the ground state, reaction with CD{sub 4} prepared in the |2100> mode leads primarily to CD{sub 3} with one quantum of stretch excitation, and reaction with CD{sub 4} prepared in the |1110> mode leads primarily to CD{sub 3} with one quantum of C-D stretch excitation in two oscillators. There are some minor deviations from this behavior, most notably that the Cl atom is able to abstract more energy than is available in a single C-D oscillator, as in the case of |2100>, wherein a small population of ground-state CD{sub 3} is observed. These exceptions likely result from the mixings between different second overtone stretch combination bands. They also measure isotropic and anisotropic time-of-flight profiles of CD{sub 3} ({nu}{sub 1}=1,2) products from the Cl+CD{sub 4} |2100> reaction, providing speed distributions, spatial anisotropies, and differential cross sections that indicate that energy introduced as vibrational energy into the system essentially remains as such throughout the course of the reaction.

  19. The unimolecular reaction of isolated CF3CN: The influence of laser fluence/intensity on the rovibronic excitation of CN(X 2Sigma + ) produced via infrared multiple photon dissociation

    NASA Astrophysics Data System (ADS)

    Reisler, H.; Kong, F.; Wittig, C.; Stone, J.; Thiele, E.; Goodman, M. F.

    1982-07-01

    Measurements of nascent CN(X 2?+) rovibronic state distributions following the unimolecular reaction CF3CN‡?CF3+CN are reported. Excitation under collision free conditions is provided by IR multiple photon excitation using the focused output from a CO2 TEA laser at fluences 3-150 J cm-2. At fluences 3-20 J cm-2, the CN(X 2?+,v'' = 0) rotational temperature increases monotonically from 500 to 1200 K with increasing fluence, while at fluences 30-150 J cm-2, the rotational and vibrational temperatures do not change and are TR = 1200±100 K and TV = 2400±150 K. At low fluences, the increase in V, R, T excitations with increasing fluence reflects an increase in the vibrational excitation of the dissociating parent molecules. The ultimate level of excitation that the parent molecules attain depends both on the fluence and the intensity of the laser, and the appearance time of the CN fragments decreases with increasing fluence, since molecules excited significantly above dissociation threshold decompose more rapidly than those near reaction threshold. At fluences ?30 J cm-2, the sample is depleted before the CO2 laser output reaches its peak intensity, thus causing the observed ''saturation'' effect in product excitation level. A straightforward model which includes effects due to laser pulse shapes can account for the experimental observations.

  20. Simultaneous two-photon excitation of photodynamic therapy agents

    SciTech Connect

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

    1998-01-01

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

  1. Communication: Existence of the doubly excited state that mediates the photoionization of azulene

    NASA Astrophysics Data System (ADS)

    Piecuch, Piotr; Hansen, Jared A.; Staedter, David; Faure, Stéphane; Blanchet, Valérie

    2013-05-01

    We use the high-level electronic structure computations based on the equation-of-motion coupled-cluster (EOMCC) theory to show that the previously postulated [V. Blanchet et al., J. Chem. Phys. 128, 164318 (2008), 10.1063/1.2913167] doubly excited state of azulene, located below the ionization threshold and mediating the 1 + 2' multi-photon ionization that leads to a Rydberg fingerprint, exists. This supports the crucial role of doubly excited states in the Rydberg fingerprint spectroscopy, while demonstrating the usefulness of EOMCC methods in capturing such states.

  2. Communication: existence of the doubly excited state that mediates the photoionization of azulene.

    PubMed

    Piecuch, Piotr; Hansen, Jared A; Staedter, David; Faure, Stéphane; Blanchet, Valérie

    2013-05-28

    We use the high-level electronic structure computations based on the equation-of-motion coupled-cluster (EOMCC) theory to show that the previously postulated [V. Blanchet et al., J. Chem. Phys. 128, 164318 (2008)] doubly excited state of azulene, located below the ionization threshold and mediating the 1 + 2' multi-photon ionization that leads to a Rydberg fingerprint, exists. This supports the crucial role of doubly excited states in the Rydberg fingerprint spectroscopy, while demonstrating the usefulness of EOMCC methods in capturing such states. PMID:23742447

  3. 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

  4. Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio [Dipartimento di Fisica 'E. R. Caianiello', Universita di Salerno, INFM UdR di Salerno, INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, 84081 Baronissi, SA (Italy)

    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.

  5. 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.

  6. Supplementary figures Noninvasive multiphoton fluorescence microscopy resolves retinol

    E-print Network

    Palczewski, Krzysztof

    to the arrows. Retinosomes (grey block) are storage structure of all­ trans­retinyl esters, and all) Dashed lines, 730 nm excitation; solid lines, 810 nm excitation; blue, 4 mM solution of all in ethanol. Blue arrow indicates a maximum at 479 nm and red arrow signifies a secondary maximum at ~521 nm

  7. Infrared Gallery

    NSDL National Science Digital Library

    Human eyes cannot see infrared wavelengths, but with the help of false-color imaging, temperature differences become visible and invisible features are suddenly illuminated. This interactive gallery shows images of a variety of objects and geothermal features in both visible and infrared light, and explains why the infrared images show the items as they do. A background essay and list of discussion questions are also provided.

  8. Multiphoton imaging in mouse models of Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Bacskai, Brian J.; Skoch, Jesse; Hickey, Gregory A.; Berezovska, Oksana; Hyman, Bradley T.

    2004-06-01

    Alzheimer's disease is characterized by the presence of neurofibrillary tangles and senile plaques in the brain. Clinical techniques are just becoming available for detecting plaques, allowing a definitive diagnosis of the disease. Using multiphoton microscopy and transgenic mouse models that develop senile plaques as they age, we have demonstrated chronic, in vivo imaging of these neuropathological lesions. We have used these tools to evaluate contrast agents with high affinity and specificity for senile plaques that would be suitable for non-invasive imaging with PET scanning if appropriately radiolabeled. These imaging tools should translate into early diagnostic procedures, as well as end-points for clinical trials aimed at clearing senile plaques from the brain. We have also developed FLIM for FRET determinations in vitro and in vivo between appropriate donor and acceptor fluorophores to examine the proximity of domains within a single protein. These results indicate that FRET measurements using FLIM can determine interactions of proteins on the nanometer scale, facilitating an understanding of both static and dynamic protein assemblies in neuropathological diseases.

  9. The analysis of aging skin based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Shulian; Li, Hui; Zhang, Xiaoman; Li, Zhifang; Xu, Shufei

    2010-11-01

    Aging is a very important issue not only in dermatology, but also in cosmetic science. Cutaneous aging involves both chronological and photoaging aging process. The chronological aging is induced with the passage of time. And the photoaging skin is the extrinsic aging caused by sun exposure. The aim of this study is to use multiphoton microscopy (MPM) in vivo to assess intrinsic-age-related and photo-age-related difference. The changes of dermal collagen are measured in quantitively. The algorithm that we used automatically produced the transversal dermal map from MPM. Others, the texture of dermis are analyzed by Fourier transform and Gray Level Co-occurrence Matrix. And the object extraction in textured images is proposed based on the method in object edge extraction, and the aim of it is to detect the object hidden in the skin texture in difference aging skin. The result demonstrates that the approach is effective in detecting the object in epidermis and dermis textured image in different aging skin. It could help to further understand the aging mechanism.

  10. Multiphoton microscopy of antigen presenting cells in experimental cancer therapies

    NASA Astrophysics Data System (ADS)

    Watkins, Simon C.; Papworth, Glenn D.; Spencer, Lori A.; Larregina, Adriana T.; Hackstein, Holger

    2002-06-01

    The absence of effective conventional therapy for most cancer patients justifies the application of novel, experimental approaches. One alternative to conventional cytotoxic agents is a more defined molecular approach for cancer immune treatment; promotion of the immune system specifically to target and eliminate tumor cells on the basis of expression of tumor-associated antigens (TAA). TAA could be presented to T-cells by professional antigen-presenting cells (APC) that generate a more efficient and effective anti-tumor immune response. In fact, it has been well documented that dendritic cells, the most immunologically potent APC, are capable of recognizing, processing and presenting TAA, in turn initiating a specific antitumor immune response. Results from several laboratories and clinical trials suggested significant but still limited efficacy of TAA-pulsed dendritic cells administered to tumor-bearing hosts. Following such delivery, it is fundamentally necessary to dynamically assess cell abundance within the microenvironment of the tumor in the presence of the appropriate therapeutic agent. Multiphoton microscopy was used to assess the trafficking of pulsed dendritic cells and other APC in skin, lymph nodes and brain of several animal tumor models, following different routes of administration.

  11. Spectra from multiphoton electron detachment of H sup minus

    SciTech Connect

    Smith, W.W. (University of Connecticut, Storrs, CT (USA)); Tang, C.Y. (University of New Mexico, Albuquerque, NM (USA)); Quick, C.R. (Los Alamos National Laboratory, Los Alamos, NM (USA)); Bryant, H.C.; Harris, P.G.; Mohagheghi, A.H. (University of New Mexico, Albuquerque, NM (USA)); Donahue, J.B.; Reeder, R.A. (Los Alamos National Laboratory, Los Alamos NM (USA)); Sharifian, H. (California State University, Long Beach, CA (USA)); Stewart, J.E. (Western Washington University, Bellingham, WA (USA)); Toutounchi, H. (University of Mashhad, Mashhad (Iran)); Cohen, S. (Los Alamos National Laboratory, Los Alamos, NM (USA)); Altman, T.C. (Oswego High School, Oswego, NY (USA)); Risolve, D.C. (St. Mary's College, Winona, MN (USA))

    1991-01-01

    New data are reported on the multiphoton detachment process in a fast beam of H{sup {minus}} ions. The angle-tuned relativistic Doppler shift is used to vary the photon energy of a focused ({similar to}10 GWm/c{sup 2}) 10.6-{mu}m CO{sub 2} laser beam from {similar to}0.05 to {similar to}0.4 eV in the rest frame (CM frame) of the fast ions. The ions are produced at 800 MeV ({beta}=v/c=0.84) by the Los Alamos Meson Physics Facility linear accelerator at Los Alamos and experience {similar to}1-psec pulses in the CM frame as they cross the laser beam focus. Peaks in the detachment signal corresponding to each order for two- to six-photon processes are observed. At modest laser intensity in the gigawatt-per-square-centimeter range, observed shifts of the apparent two-photon threshold are found to be not more than 30--50% of the expected maximum shift, based on the value of the ponderomotive potential. Experimental uncertainties are due mainly to imprecise knowledge of the maximum laser intensity. The data analysis and experiments are continuing.

  12. Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy.

    PubMed

    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. PMID:23515864

  13. Multiphoton imaging the disruptive nature of sulfur mustard lesions

    NASA Astrophysics Data System (ADS)

    Werrlein, Robert J.; Braue, Catherine R.; Dillman, James F.

    2005-03-01

    Sulfur mustard [bis-2-chloroethyl sulfide] is a vesicating agent first used as a weapon of war in WWI. It causes debilitating blisters at the epidermal-dermal junction and involves molecules that are also disrupted by junctional epidermolysis bullosa (JEB) and other blistering skin diseases. Despite its recurring use in global conflicts, there is still no completely effective treatment. We have shown by imaging human keratinocytes in cell culture and in intact epidermal tissues that the basal cells of skin contain well-organized molecules (keratins K5/K14, ?6?4 integrin, laminin 5 and ?3?1 integrin) that are early targets of sulfur mustard. Disruption and collapse of these molecules is coincident with nuclear displacement, loss of functional asymmetry, and loss of polarized mobility. The progression of this pathology precedes basal cell detachment by 8-24 h, a time equivalent to the "clinical latent phase" that defines the extant period between agent exposure and vesication. Our images indicate that disruption of adhesion-complex molecules also impairs cytoskeletal proteins and the integration of structures required for signal transduction and tissue repair. We have recently developed an optical system to test this hypothesis, i.e., to determine whether and how the early disruption of target molecules alters signal transduction. This environmentally controlled on-line system provides a nexus for real-time correlation of imaged lesions with DNA microarray analysis, and for using multiphoton microscopy to facilitate development of more effective treatment strategies.

  14. Unconditionally secure key distillation from multi-photons

    E-print Network

    Kiyoshi Tamaki; Hoi-Kwong Lo

    2006-01-24

    In this paper, we prove that the unconditionally secure key can be surprisingly extracted from {\\it multi}-photon emission part in the photon polarization-based QKD. One example is shown by explicitly proving that one can indeed generate an unconditionally secure key from Alice's two-photon emission part in ``Quantum cryptography protocols robust against photon number splitting attacks for weak laser pulses implementations'' proposed by V. Scarani {\\it et al.,} in Phys. Rev. Lett. {\\bf 92}, 057901 (2004), which is called SARG04. This protocol uses the same four states as in BB84 and differs only in the classical post-processing protocol. It is, thus, interesting to see how the classical post-processing of quantum key distribution might qualitatively change its security. We also show that one can generate an unconditionally secure key from the single to the four-photon part in a generalized SARG04 that uses six states. Finally, we also compare the bit error rate threshold of these protocols with the one in BB84 and the original six-state protocol assuming a depolarizing channel.

  15. 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.

  16. Flexible digital signal processing architecture for narrowband and spread-spectrum lock-in detection in multiphoton microscopy and time-resolved spectroscopy.

    PubMed

    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. PMID:25832238

  17. 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.

  18. Infrared Thermometers

    NSDL National Science Digital Library

    John Schaefers

    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. Students will enjoy this inquiry-based activity as they use infrared thermometers to examine various materials, metals, color surfaces, and textures on a car.

  19. Multiphoton ionization and high-order harmonic generation of H2+ in intense ultrashort elliptically polarized laser fields

    NASA Astrophysics Data System (ADS)

    Nasiri Avanaki, Kobra; Chu, Shih-I.; Telnov, Dmitry A.

    2014-05-01

    We present an ab initio 3D calculation of multiphoton ionization (MPI) and high-order harmonic generation (HHG) of the hydrogen molecular ion subject to intense elliptically polarized laser pulses. The numerical procedure involves the extension of the generalized pseudospectral (GPS) method for non-uniform spatial discretization of the Hamiltonian and wave functions in prolate spheroidal coordinates; the time propagation scheme is based on the split-operator technique in the energy representation. The calculations are performed for the ground and first excited electronic states of H2+at the equilibrium internuclear separation R = 2 a.u. as well as for the stretched molecule at R = 7 a.u. The dependence of the HHG spectra on the ellipticity parameter is analyzed. The spectral and temporal structures of the HHG signal are studied by means of the wavelet time-frequency analysis. The results provide new insights regarding the detailed HHG mechanisms in elliptically polarized laser fields. This work is partially supported by DOE.

  20. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments.

    PubMed

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo; Zheng, Xianfeng; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-01

    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(1) and 6(1)1(1) vibronic levels in the S1 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(-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. PMID:26133827

  1. 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., E-mail: alexeenk@purdue.edu [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Shneider, Mikhail N. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    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.

  2. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments

    NASA Astrophysics Data System (ADS)

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo; Zheng, Xianfeng; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-01

    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 61 and 6111 vibronic levels in the S1 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-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.

  3. Multi-Photon Quantum Key Distribution Based on Double-Lock Encryption

    E-print Network

    Kam Wai Clifford Chan; Mayssaa El Rifai; Pramode K. Verma; Subhash Kak; Yuhua Chen

    2015-03-19

    This paper presents a multi-stage, multi-photon quantum key distribution protocol based on the double-lock cryptography. It exploits the asymmetry in the detection strategies between the legitimate users and the eavesdropper. The security analysis of the protocol is presented with coherent states under the intercept-resend attack, the photon number splitting attack, and the man-in-the-middle attack. It is found that the mean photon number can be much larger than one. This complements the recent interest in multi-photon quantum communication protocols that require a pre-shared key between the legitimate users.

  4. Diagrammatic analysis of multiphoton processes in a ladder-type three-level atomic system

    SciTech Connect

    Noh, Heung-Ryoul [Department of Physics, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Moon, Han Seb [Department of Physics, Pusan National University, Busan 609-735 (Korea, Republic of)

    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.

  5. Identification of cartilage injury using quantitative multiphoton microscopy

    PubMed Central

    Novakofski, Kira D.; Williams, Rebecca M.; Fortier, Lisa A.; Mohammed, Hussni O.; Zipfel, Warren R.; Bonassar, Lawrence J.

    2014-01-01

    Objective Cartilage injury can lead to post-traumatic osteoarthritis (PTOA). Immediate post-trauma cellular and structural changes are not widely understood. Furthermore, current cellular-resolution cartilage imaging techniques require sectioning of cartilage and/or use of dyes not suitable for patient imaging. In this study, we used multiphoton microscopy (MPM) data with FDA-approved sodium fluorescein to identify and evaluate the pattern of chondrocyte death after traumatic injury. Method Mature equine distal metacarpal or metatarsal osteochondral blocks were injured by 30 MPa compressive loading delivered over 1 sec. Injured and control sites were imaged unfixed and in situ 1 hour post-injury with sodium fluorescein using rasterized z-scanning. MPM data was quantified in MATLAB, reconstructed in 3-D, and projected in 2-D to determine the damage pattern. Results MPM images (600 per sample) were reconstructed and analyzed for cell death. The overall distribution of cell death appeared to cluster into circular (n=7) or elliptical (n=4) patterns (p=0.006). Dead cells were also prevalent near cracks in the matrix, with only 26.3% (SE=5.0%, p<0.0001) of chondrocytes near cracks being viable. Conclusion This study demonstrates the first application of MPM for evaluating cellular-scale cartilage injury in situ in live tissue, with clinical potential for detecting early cartilage damage. With this technique, we were able to uniquely observe two death patterns resulting from the same compressive loading, which may be related to local variability in matrix structure. These results also demonstrate proof-of-concept MPM diagnostic use in detecting subtle and early cartilage damage not detectable in any other way. PMID:24185113

  6. A combined resonance enhanced multiphoton ionization and ab initio study of the first absorption band of 1,2,4,5-tetrafluorobenzene, pentafluorobenzene, and hexafluorobenzene

    NASA Astrophysics Data System (ADS)

    Ridley, Trevor; Rogers, David M.; Lawley, Kenneth P.

    2014-10-01

    The resonance enhanced multiphoton ionization (REMPI) spectra of jet-cooled penta- and hexafluorobenzene when excited in the region ?ex = 265-253 nm of the first absorption band and observed only in the CF+ mass channel is dominated by rotational structure in the A?X transition of CF. However, structure in the CF+ channel for ?ex > 265 nm is not a continuation of this CF spectrum and is assigned to vibrational activity in two low-frequency modes of a distorted excited state of the parent molecule. The vibrational structure is assigned to the lowest ??* state from a comparison with the equivalent spectrum of 1,2,4,5-tetrafluorobenzene. Ab initio calculations at the CIS level of theory of the ??* state of the penta- and hexafluorobenzene reveal a much more distorted equilibrium geometry (C1 symmetry) than that of 1,2,4,5-tetrafluorobenzene. Long progressions observed in the ?ex > 265 nm REMPI spectra of C6HF5 and C6F6 are assigned to two very low frequency (˜30 and 80 cm-1) modes. The role of the close-lying ??* and ??* states in determining the energy redistribution of the initially excited state by internal conversion is discussed. Both the fluorescent yield and the direct production of CF(X) are associated with transfer to the lower-lying ??* state.

  7. OPTIMIZING MULTI-PHOTON FLUORESCENCE MICROSCOPY LIGHT COLLECTION FROM LIVING TISSUE BY NON-CONTACT TOTAL EMISSION DETECTION (epiTED)

    PubMed Central

    Combs, Christian A.; Smirnov, Aleksandr; Chess, David; McGavern, Dorian B.; Schroeder, James L.; Riley, Jason; Kang, Silvia S.; Lugar-Hammer, Merav; Gandjbakhche, Amir; Knutson, Jay R.; Balaban, Robert S.

    2012-01-01

    Summary A benefit of multiphoton fluorescence microscopy is the inherent optical sectioning that occurs during excitation at the diffraction-limited spot. The scanned collection of fluorescence emission is incoherent; i.e., no real image needs to be formed on the detector plane. The nearly isotropic emission of fluorescence excited at the focal spot allows for new detection schemes that efficiently funnel all attainable photons to detector(s). We previously showed (Combs et al., 2007) that parabolic mirrors and condensers could be combined to collect the totality of solid angle around the excitation spot for tissue blocks, leading to ~8-fold signal gain. Using a similar approach, we have developed an in vivo Total Emission Detection (epiTED) instrument modified to make non-contact images from outside of living tissue. Simulations suggest that a ~4 fold enhancement may be possible (much larger with lower NA objectives than the 0.95 NA used here) with this approach depending on objective characteristics, imaging depth and the characteristics of the sample being imaged. In our initial prototype, two fold improvements were demonstrated in the mouse brain and skeletal muscle as well as the rat kidney using a variety of fluorophores and no compromise of spatial resolution. These results show this epiTED effectively doubles emission signal in vivo ; thus, it will maintain the image signal to noise ratio (SNR) at two times the scan rate or enable full scan rate at approximately 30% reduced laser power (to minimize photo-damage). PMID:21118209

  8. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water-dimer III: Mixed Jacobi-valence parametrization and benchmark results for the zero point energy, vibrationally excited states, and infrared spectrum

    Microsoft Academic Search

    Oriol Vendrell; Michael Brill; Fabien Gatti; David Lauvergnat; Hans-Dieter Meyer

    2009-01-01

    Quantum dynamical calculations are reported for the zero point energy, several low-lying vibrational states, and the infrared spectrum of the H5O2+ cation. The calculations are performed by the multiconfiguration time-dependent Hartree (MCTDH) method. A new vector parametrization based on a mixed Jacobi-valence description of the system is presented. With this parametrization the potential energy surface coupling is reduced with respect

  9. Multiphoton amplification processes and quantum-path interferences in a coherently driven atomic vapor

    E-print Network

    Gauthier, Daniel

    Departament de Fi´sica i Enginyeria Nuclear, Universitat Polite`cnica de Catalunya, Colom 11, E-08222 Terrassa the differences with respect to the behavior of single-photon or other multiphoton amplification processes-photon population inversion is achieved using a coherent driving field, which leads to nar- row amplification

  10. Multiphoton lasing in atomic potassium: Steady-state and dynamic behavior J. L. Font,1

    E-print Network

    Gauthier, Daniel

    Multiphoton lasing in atomic potassium: Steady-state and dynamic behavior J. L. Font,1 J. J. Fernández-Soler,1 R. Vilaseca,1 and Daniel J. Gauthier2 1 Departament de Física i Enginyeria Nuclear-Rayleigh processes can become simultaneously resonant, entailing in such case a large and fast transfer of population

  11. Multiphoton microscopy using intrinsic signals for pharmacological studies in unstained cardiac and vascular tissue

    Microsoft Academic Search

    Emmanuel Beaurepaire; Thierry Boulesteix; Ana-Maria Pena; Nicole Pages; Karim Senni; Gaston Godeau; Martin-Pierre Sauviat; Marie-Claire Schanne-Klein

    2005-01-01

    We report two novel applications of multiphoton microscopy for pharmacological studies of unstained cardiovascular tissue. First, we show that second harmonic generation (SHG) microscopy of unstained cardiac myocytes can be used to determine the sarcomere length with sub-resolution accuracy, owing to the remarkable contrast of the SHG signal originating from myosin filaments. A measurement precision of 20 nm is achieved,

  12. Clinical combination of multiphoton tomography and high frequency ultrasound imaging for evaluation of skin diseases

    NASA Astrophysics Data System (ADS)

    König, K.; Speicher, M.; Koehler, M. J.; Scharenberg, R.; Elsner, P.; Kaatz, M.

    2010-02-01

    For the first time, high frequency ultrasound imaging, multiphoton tomography, and dermoscopy were combined in a clinical study. Different dermatoses such as benign and malign skin cancers, connective tissue diseases, inflammatory skin diseases and autoimmune bullous skin diseases have been investigated with (i) state-of-the-art and highly sophisticated ultrasound systems for dermatology, (ii) the femtosecond-laser multiphoton tomograph DermaInspectTM and (iii) dermoscopes. Dermoscopy provides two-dimensional color imaging of the skin surface with a magnification up to 70x. Ultrasound images are generated from reflections of the emitted ultrasound signal, based on inhomogeneities of the tissue. These echoes are converted to electrical signals. Depending on the ultrasound frequency the penetration depth varies from about 1 mm to 16 mm in dermatological application. The 100-MHz-ultrasound system provided an axial resolution down to 16 ?m and a lateral resolution down to 32 ?m. In contrast to the wide-field ultrasound images, multiphoton tomography provided horizontal optical sections of 0.36×0.36 mm2 down to 200 ?m tissue depth with submicron resolution. The autofluorescence of mitochondrial coenzymes, melanin, and elastin as well as the secondharmonic- generation signal of the collagen network were imaged. The combination of ultrasound and multiphoton tomography provides a novel opportunity for diagnostics of skin disorders.

  13. Multiphoton NMR spectroscopy on a spin system with I=1\\/2

    Microsoft Academic Search

    Y. Zur; M. H. Levitt; S. Vega

    1983-01-01

    Multiple quantum effects in double frequency (df) pulsed NMR experiments on multilevel spin systems are studied. In these experiments, the spin systems are irradiated by two rf fields, applied simultaneously. A general theoretical description of these experiments is presented using the theory of Shirley for time dependent Hamiltonians. Multiphoton resonance conditions are given and time independent fictitious spin-1\\/2 Hamiltonians are

  14. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio [Dipartimento di Fisica 'E.R. Caianiello', Universita di Salerno, INFM UdR di Salerno, INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, 84081 Baronissi, SA (Italy)

    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.

  15. A SINGLE-PHOTON ON-DEMAND SOURCE WITH DECOUPLED SINGLE AND MULTIPHOTON

    E-print Network

    Migdall, Alan

    A SINGLE-PHOTON ON-DEMAND SOURCE WITH DECOUPLED SINGLE AND MULTIPHOTON PROBABILITIES: INITIAL of a multiplexed downconversion system designed to pro- duce a single-photon on-demand source, by a multiple delay line trigger, yielding a single-photon certification of the produced photons. We discuss theoretically

  16. Multiphoton imaging microscopy at deeper layers with adaptive optics control of spherical aberration

    NASA Astrophysics Data System (ADS)

    Bueno, Juan M.; Skorsetz, Martin; Palacios, Raquel; Gualda, Emilio J.; Artal, Pablo

    2014-01-01

    Despite the inherent confocality and optical sectioning capabilities of multiphoton microscopy, three-dimensional (3-D) imaging of thick samples is limited by the specimen-induced aberrations. The combination of immersion objectives and sensorless adaptive optics (AO) techniques has been suggested to overcome this difficulty. However, a complex plane-by-plane correction of aberrations is required, and its performance depends on a set of image-based merit functions. We propose here an alternative approach to increase penetration depth in 3-D multiphoton microscopy imaging. It is based on the manipulation of the spherical aberration (SA) of the incident beam with an AO device while performing fast tomographic multiphoton imaging. When inducing SA, the image quality at best focus is reduced; however, better quality images are obtained from deeper planes within the sample. This is a compromise that enables registration of improved 3-D multiphoton images using nonimmersion objectives. Examples on ocular tissues and nonbiological samples providing different types of nonlinear signal are presented. The implementation of this technique in a future clinical instrument might provide a better visualization of corneal structures in living eyes.

  17. 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.

  18. Electron-nuclear energy sharing in above-threshold multiphoton dissociative ionization of H2.

    PubMed

    Wu, J; Kunitski, M; Pitzer, M; Trinter, F; Schmidt, L Ph H; Jahnke, T; Magrakvelidze, M; Madsen, C B; Madsen, L B; Thumm, U; Dörner, R

    2013-07-12

    We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles. PMID:23889391

  19. Semiclassical analysis of long-wavelength multiphoton processes: The periodically driven harmonic oscillator

    E-print Network

    Vela-Arevalo, Luz V.

    Semiclassical analysis of long-wavelength multiphoton processes: The periodically driven harmonic to obtain a nonperturbative analysis. When applied to the standard vector potential coupling, an exact application of the Goeppert- Mayer gauge. While the analysis to this point is general and aimed at microwave

  20. Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2

    E-print Network

    Thumm, Uwe

    Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2 J. Wu­4], where the photon energy is shared by the freed electrons and the nuclear fragments. For the molecular ionization [10­15], and the imaging of inter- nuclear distance using nuclear kinetic energy release spec- tra

  1. Multiphoton imaging with vibrational contrast and high spatial resolution

    Microsoft Academic Search

    Keith Ryan Cohn

    2007-01-01

    Imaging with mid-infrared (mid-IR) radiation is useful for spectroscopic purposes because light of this energy corresponds to vibrational resonances in molecular systems. However, diffraction limits the spatial resolution of conventional imaging techniques to approximately the wavelength of the source light, which often proves insufficient for samples with subwavelength features. We have explored three novel avenues of circumventing the diffraction barrier

  2. Rotational spectroscopy of the first excited state of the acetylenic C–H stretch of 3-fluoropropyne performed by infrared-Fourier transform microwave–microwave triple-resonance spectroscopy

    Microsoft Academic Search

    Kevin O. Douglass; Frances S. Rees; Richard D. Suenram; Brooks H. Pate; Igor Leonov

    2005-01-01

    The rotational spectra of 3-fluoropropyne in the ground and first excited acetylenic C–H stretch vibrational state have been measured. The pure rotational spectrum of the normal species and the 13C isotopomers were measured using FTMW-cwMW double-resonance spectroscopy based on the Autler–Townes (AC Stark) effect. The lineshape properties of this measurement make it possible to determine the transition strength, ?J-selection rules,

  3. Particle Beam Excitation Electron Beam Excitation

    E-print Network

    Schroder, Dieter K.

    Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAMParticle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Projector lens Electron multiplier Fluorescent screen X-Y stage Microchannel plate Immersion lens Measures m

  4. Sequential multiphoton multiple ionization of Ar and Xe by X-ray free electron laser pulses at SACLA

    NASA Astrophysics Data System (ADS)

    Fukuzawa, H.; Motomura, K.; Son, S.-K.; Mondal, S.; Tachibana, T.; Ito, Y.; Kimura, M.; Nagaya, K.; Sakai, T.; Matsunami, K.; Wada, S.; Hayashita, H.; Kajikawa, J.; Liu, X.-J.; Feifel, R.; Johnsson, P.; Siano, M.; Kukk, E.; Rudek, B.; Erk, B.; Foucar, L.; Robert, E.; Miron, C.; Tono, K.; Inubushi, Y.; Hatsui, T.; Yabashi, M.; Yao, M.; Santra, R.; Ueda, K.

    2014-04-01

    We have investigated multiphoton multiple ionization of Ar and Xe atoms irradiated by intense X-ray pulses using the new X-ray free electron laser facility SACLA. The experimental results are compared with theoretical results.

  5. 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 ...

  6. Many-mode Floquet theoretical approach for coherent control of multiphoton dynamics driven by intense frequency-comb laser fields

    E-print Network

    Son, Sang-Kil; Chu, Shih-I

    2008-06-05

    We extend the many-mode Floquet theorem (MMFT) for the investigation of multiphoton resonance dynamics driven by intense frequency-comb laser fields. The frequency comb structure generated by a train of short laser pulses ...

  7. Multi-Photon Laser Spectroscopy of Transition Ions in Crystals: Recent Progress in the Use of Symmetry Considerations

    E-print Network

    M. Kibler

    1998-10-26

    The role of symmetry adaptation techniques in multi-photon spectroscopy of partly-filled shell ions in crystals is briefly reviewed. This leads to an intensity formula which is discussed from a qualitative point of view.

  8. 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.

  9. Infrared surface polaritons on bismuth

    NASA Astrophysics Data System (ADS)

    Khalilzadeh-Rezaie, Farnood; Smith, Christian W.; Nath, Janardan; Nader, Nima; Shahzad, Monas; Cleary, Justin W.; Avrutsky, Ivan; Peale, Robert E.

    2015-01-01

    Optical constants for evaporated bismuth (Bi) films were measured by ellipsometry and compared with those published for single crystal and melt-cast polycrystalline Bi in the wavelength range of 1 to 40 ?m. The bulk plasma frequency ?p and high-frequency limit to the permittivity ?? were determined from the long-wave portion of the permittivity spectrum, taking previously published values for the relaxation time ? and effective mass m*. This part of the complex permittivity spectrum was confirmed by comparing calculated and measured reflectivity spectra in the far-infrared. Properties of surface polaritons (SPs) in the long-wave infrared were calculated to evaluate the potential of Bi for applications in infrared plasmonics. Measured excitation resonances for SPs on Bi lamellar gratings agree well with calculated resonance spectra based on grating geometry and complex permittivity.

  10. Mid-Infrared Diagnostics of LINERs

    E-print Network

    E. Sturm; D. Rupke; A. Contursi; D. -C. Kim; D. Lutz; H. Netzer; S. Veilleux; R. Genzel; M. Lehnert; L. J. Tacconi; D. Maoz; J. Mazzarella; S. Lord; D. Sanders; A. Sternberg

    2006-10-26

    We report results from the first mid-infrared spectroscopic study of a comprehensive sample of 33 LINERs, observed with the Spitzer Space Telescope. We compare the properties of two different LINER populations: infrared-faint LINERs, with LINER emission arising mostly in compact nuclear regions, and infrared-luminous LINERs, which often show spatially extended (non-AGN) LINER emission. We show that these two populations can be easily distinguished by their mid-infrared spectra in three different ways: (i) their mid-IR spectral energy distributions (SEDs), (ii) the emission features of polycyclic aromatic hydrocarbons (PAHs), and (iii) various combinations of IR fine-structure line ratios. IR-luminous LINERs show mid-IR SEDs typical of starburst galaxies, while the mid-IR SEDs of IR-faint LINERs are much bluer. PAH flux ratios are significantly different in the two groups. Fine structure emission lines from highly excited gas, such as [O IV], are detected in both populations, suggesting the presence of an additional AGN also in a large fraction of IR-bright LINERs, which contributes little to the combined mid-IR light. The two LINER groups occupy different regions of mid-infrared emission-line excitation diagrams. The positions of the various LINER types in our diagnostic diagrams provide important clues regarding the power source of each LINER type. Most of these mid-infrared diagnostics can be applied at low spectral resolution, making AGN- and starburst-excited LINERs distinguishable also at high redshifts.

  11. 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.

  12. Multiphoton ionization and ion-pair formation in molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; McCormack, E. F.; Dehmer, J. L.; Dehmer, P. M.

    1992-07-01

    We have investigated both photoionization and ion-pair formation in molecular hydrogen by using double-resonance excitation via the E,F (sup 1)Sigma(sub g)(sup +), v=6 level. The energetic threshold for ion-pair formation occurs just below the H(sub 2)(sup +) X (sup 2)Sigma(sub g)(sup +), v(sup +)=9 ionization threshold. The spectrum in this region was studied by using both conventional and constant-ionic-state photoelectron spectroscopy, as well as by monitoring the H(sup -) production. The decay dynamics in this region are extremely rich, because excited levels may decay by rotational and vibrational autoionization, by predissociation to neutral H + H* (n=2,3,4), by predissociation to the ion pair H(sup +) + H(sup -), and by fluorescence. In addition, the dissociative potential curve of the 2p(sigma)(sub u)3s(sigma)(sub g) (sup 1)Sigma(sub u)(sup +) doubly excited electronic state crosses the H(sub 2)(sup +) X (sup 2)Sigma(sub u)(sup +) potential curve in the same energy region, and the electronic autoionization of this state is found to significantly influence these decay processes.

  13. 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…

  14. Infrared Spectroscopy

    NSDL National Science Digital Library

    C. P. Sherman Hsu

    This 38-page PDF document is a chapter from the Handbook of Instrumental Techniques for Analytical Chemistry. The chapter explains how infrared spectroscopy works (no comma) along with its general uses, common applications, range and limitations. Also included are spectrometer designs, information about sample preparation, analytical methods, related methods such as gas chromotography and diffuse reflectance, and costs and instrument vendors.

  15. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Isotopically selective IR multiphoton dissociation of CF3I molecules in a pulsed gasdynamic flow

    NASA Astrophysics Data System (ADS)

    Makarov, Grigorii N.; Lokhman, V. N.; Malinovskii, D. E.; Ogurok, D. D.

    1998-06-01

    An investigation was made of isotopically selective IR multiphoton dissociation of CF3I molecules in a pulsed gasdynamic flow. The dependences of the C2F6 product yield on the energy density of the exciting laser radiation, on the CF3I pressure above a nozzle, and on the number of pulses were obtained. The dependence of the 13C content in C2F6 on the exciting radiation frequency was also found. The conditions for dissociation of molecules optimal in respect of the C2F6 yield and the enrichment factor were identified. It was established that the C2F6 yield fell strongly on reduction of the CF3I concentration in the flow, which was related to the loss of the product CF3 radicals at the walls. The use of a low-pressure buffer (acceptor) gas, in the chamber where the molecular flow was formed, reduced the radical losses and increased the product yield.

  16. Gas phase infrared multiple-photon dissociation spectra of methanol, ethanol and propanol proton-bound dimers, protonated propanol and the propanol\\/water proton-bound dimer

    Microsoft Academic Search

    Travis D. Fridgen; Luke Macaleese; Terry B. McMahon; Joel Lemaire; Philippe Maitre

    2006-01-01

    The infrared multiphoton dissociation (IRMPD) spectra of three homogenous proton-bound dimers are presented and the major features are assigned based on comparisons with the neutral alcohol and with density functional theory calculations. As well, the IRMPD spectra of protonated propanol and the propanol\\/water proton-bound dimer (or singly hydrated protonated propanol) are presented and analysed. Two primary IRMPD photoproducts were observed

  17. Pre-excitation studies for rubidium-plasma generation

    NASA Astrophysics Data System (ADS)

    Aladi, Márk; Bakos, József; Barna, I. F.; Czitrovszky, Aladár; Djotyan, Gagik; Dombi, Péter; Dzsotjan, David; Földes, István; Hamar, Gerg?; Ignácz, Péter; Kedves, Miklós; Kerekes, Attila; Lévai, Péter; Márton, István; Nagy, Attila; Oszetzky, Dániel; Pocsai, Mihály; Rácz, Péter; Ráczkevi, Béla; Szigeti, János; Sörlei, Zsuzsa; Szipöcs, Róbert; Varga, Dezs?; Varga-Umbrich, Károly; Varró, Sándor; Vámos, Lénárd; Vesztergombi, György

    2014-03-01

    The key element in the Proton-Driven-Plasma-Wake-Field-Accelerator (PWFA) project is the generation of highly uniform plasma from Rubidium vapor. A scientifically straightforward, yet highly challenging way to achieve full ionization is to use high power laser which can assure the barrier suppression ionization (BSI) along the 10 m long active region. The Wigner-team in Budapest is investigating an alternative way of uniform plasma generation. The proposed Resonance Enhanced Multi-Photon Ionization (REMPI) scheme can be probably realized by much less laser power. In the following we plan to investigate the resonant pre-excitations of the Rb atoms, both theoretically and experimentally. In the following our theoretical framework is presented together with the status report about the preparatory work of the planned experiment.

  18. Non-Gaussian features from excited squeezed vacuum state

    NASA Astrophysics Data System (ADS)

    Tang, Xu-bing; Gao, Fang; Wang, Yao-xiong; Wu, Jian-guang; Shuang, Feng

    2015-06-01

    In this work, we introduce a non-Gaussian quantum state named excited squeezed vacuum state (ESVS), which can be utilized to describe quantum light field emitted from the multiphoton quantum process occurred in some restricted quantum systems. We investigate its nonclassical properties such as Wigner distribution in phase space, photon number distribution, the second-order autocorrelation and the quadrature fluctuations. By virtue of the methods of Hilbert-Schmidt distance and quantum relative entropy (QRE), we quantify the non-Gaussianity of the ESVS, respectively. Due to the similar photon statistics, we examine the fidelity between the ESVS and the photon-subtraction squeezed vacuum state (PSSVS), and then find the optimal fidelity by monitoring the relevant parameters. Considering a thermal lossy channel, we examine the evolution of Wigner function for the ESVS.

  19. Starch granules as a probe for the polarization at the sample plane of a high resolution multiphoton microscope

    NASA Astrophysics Data System (ADS)

    Psilodimitrakopoulos, Sotiris; Amat-Roldán, Ivan; Santos, Susana; Mathew, Manoj; Thayil K. N., Anisha; Zalvidea, Dobryna; Artigas, David; Loza-Alvarez, Pablo

    2008-02-01

    Because of its polarization sensitivity, SHG microscopy can provide information about the orientation and degree of structural organization inside biological samples. To fully exploit the above potential, the state of the polarization at the sample plane needs to be known. In this work we present starch granules as a reliable probe for the polarization state of the excitation beam at the sample plane of a high resolution multiphoton microscope. Polarization dependent SHG series of images demonstrated the radial distribution of SHG active molecules inside starch granules. This allowed the granule to exhibit symmetrical SHG emission regions. The pattern rotates along with the rotation of a ?/2 waveplate and thus, can demonstrate the polarization at the sample plane. Maximum signal in the forward detected geometry appears when imaging starch granules exactly at the hemisphere plane. Symmetric SHG regions rotating with the incoming linear polarization were also recorded in the backward detected geometry. A portion of the backwards detected SHG signal, which corresponds to two rotating equator arcs, does not overlap with the forward SHG signal. Importantly, polarization measurements, performed either in the forward or the backwards directions, have demonstrated the suitability and flexibility of this technique for both detection schemes. As result, observation of the starch signal allowed us to know the polarization of our SHG microscope. Furthermore, by coding this information in an angular representation, we corrected the input values in a theoretical model that predicts the average orientation of SHG active molecules. This has allowed us to map the mean orientation of SHG active molecules in body walls muscle of Caenorhabditis elegans, with pixel resolution.

  20. Backward second-harmonic generation from starch for in-situ real-time pulse characterization in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Thayil K. N., Anisha; Gualda, Emilio J.; Cormack, Iain G.; Soria, Silvia; Loza-Alvarez, Pablo

    2007-02-01

    It is well known that the efficiency and selectivity of two-photon excited fluorescence (TPEF) process can depend on various parameters of the ultrashort pulses, such as the pulse intensity and phase, which interact with the specimen. In order to completely understand this dependence and to obtain optimal TPEF images, techniques like Collinear Frequency Resolved Optical Gating (CFROG) arrangement can be implemented in a microscope for complete pulse characterisation at the sample plane. However, this adds complexity that that additional forward collecting optics is required as well as a suitable frequency doubling crystal. Here we report a simple way to characterize the pulses within a multiphoton microscope that do not require forward collecting optics. This is achieved by taking advantage of the fact that backward propagating second harmonic generation (SHG) signal can be easily generated from starch granules. Since both the fluorescence and SHG signals can be collected using the same detection scheme the experimental arrangement is considerably simplified. Starch, being a non- toxic and non-soluble material does not affect living cells allowing the pulse characteristics to be measured in situ, without the need to move the sample. We obtained real-time SHG-autocorrelations traces by using a single starch granule that was placed alongside the living HeLa cells (GFP labeled) being imaged. Furthermore by placing a spectrometer at the output port of the microscope, a spectrally resolved SHG autocorrelation was acquired allowing complete characterisation of the pulse to be carried out. The temporal intensity and phase profile were retrieved using CFROG technique. Marginal analysis was carried out to ensure that the experimental data was successfully acquired.

  1. Development of a multispectral multiphoton fluorescence lifetime imaging microscopy system using a streak camera

    NASA Astrophysics Data System (ADS)

    Qu, Junle; Liu, Lixin; Guo, Baoping; Lin, Ziyang; Hu, Tao; Tian, Jindong; Wang, Shuyan; Zhang, Jikang; Niu, Hanben

    2005-01-01

    We report on the development of a multispectral multiphoton fluorescence lifetime imaging microscopy (MM-FLIM) system that is the combination a streak camera, a prism spectrophotometer, a femtosecond Ti: Sapphire laser and a fluorescence microscope. This system is versatile with multispectral capability, high temporal (10ps) and spatial (0.36?m) resolution and can be used to make 3-dimensional (3D) (x-y-z) multiphoton fluorescence intensity, spectrally resolved intensity and lifetime measurements with a single detector. The system was calibrated with a F-P etalon and a standard fluorescent dye and the lifetime value obtained was in good agreement with the value reported in the literature. Preliminary results suggest that this MM-FLIM system has integrated high temporal, spatial, and spectral resolution fluorescence detection in one microscopy system. Potential applications of this system include multiwell imaging, tissue discrimination, intracellular physiology and fluorescence resonance energy transfer imaging.

  2. 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.

  3. Laboratory Infrared Spectroscopy of Cationic Polycyclic Aromatic Hydrocarbon Molecules

    Microsoft Academic Search

    Jos Oomens; A. G. G. M. Tielens; Boris G. Sartakov; Gert von Helden; Gerard Meijer

    2003-01-01

    Infrared spectroscopy of a variety of interstellar sources shows strong mid-IR emission bands, which are generally attributed to emission from highly vibrationally excited polycyclic aromatic hydrocarbon molecules (PAHs) in the neutral and, particularly, cationic states. Over the past decade, various experimental methods have been developed to record the infrared spectra of cationic PAHs in the laboratory. In this paper, we

  4. Multiphoton ionization and third-harmonic generation in atoms and molecules

    SciTech Connect

    Miller, J.C.; Compton, R.N.

    1982-01-01

    We will discuss recent experiments on multiphoton ionization and third-harmonic generation in rare gases and small molecules using focused laser power densities of 10/sup 9/ to 10/sup 11/ W/cm/sup 2/. Also, some elementary experiments using vacuum ultraviolet light generated by frequency tripling in xenon and krypton will be described. These experiments include absorption and ionization studies using vacuum ultraviolet radiation as well as two-photon ionization using one vacuum ultraviolet photon and one laser photon.

  5. Multiphoton lithography of nanocrystalline platinum and palladium for site-specific catalysis in 3D microenvironments.

    PubMed

    Zarzar, Lauren D; Swartzentruber, B S; Harper, Jason C; Dunphy, Darren R; Brinker, C Jeffrey; Aizenberg, Joanna; Kaehr, Bryan

    2012-03-01

    Integration of catalytic nanostructured platinum and palladium within 3D microscale structures or fluidic environments is important for systems ranging from micropumps to microfluidic chemical reactors and energy converters. We report a straightforward procedure to fabricate microscale patterns of nanocrystalline platinum and palladium using multiphoton lithography. These materials display excellent catalytic, electrical, and electrochemical properties, and we demonstrate high-resolution integration of catalysts within 3D defined microenvironments to generate directed autonomous particle and fluid transport. PMID:22335831

  6. Multiphoton dissociation of CF3I molecules in the presence of Br2 and NO

    SciTech Connect

    Velichko, A.M.; Gordon, E.B.; Nadeikin, A.A.; Nikitin, A.I.; Tal'roze, V.L.

    1985-09-01

    The secondary chemical processes accompanying the multiphoton dissociation of CF/sub 3/ I modecules in the presence of NO and Br/sub 2/ are studied. The rate constants for the reactions I + I + NO ..-->.. I/sub 2/ and I + Br/sub 2/ ..-->.. IBr + Br are determined. The authors note that the CO/sub 2/ laser energy absorbed by these mixtures must also be the same.

  7. Imaging the ``missing'' bands in the resonance-enhanced multiphoton ionization detection of methyl radical

    Microsoft Academic Search

    Bailin Zhang; Jinghui Zhang; Kopin Liu

    2005-01-01

    Three small features were uncovered in the (2+1) resonance-enhanced multiphoton ionization spectra of CD3 produced from a crossed-beam reaction of F+CHD3 near reaction threshold. Taking the velocity mapped images of these features revealed several well-resolved ringlike structures. By conservation of energy, these spectral features were unambiguously assigned to the ``missing'' bands of 111, 311, and 411 in the literature. These

  8. Quantum Electrodynamics of Multiphoton Processes: Laser Physics, Thermal Radiation and Astrophysics

    Microsoft Academic Search

    Mark E. Perel’man

    2008-01-01

    QED description of multiphoton processes (MPP) requires special account of densities j(?) of incident photons fluxes. The reaction rate of N -photon process in laser field is expressed via (j\\/j\\u000a 0)\\u000a N\\u000a , where j\\u000a 0=1\\/?(?)?(?) is the density of reactions saturation and\\/or the threshold of opening new channel of reaction, ?(?) and ?(?) are the cross-section of elastic scattering

  9. Ultrasensitive absorption detection of protein and DNA microarrays based on nonlinear multiphoton wave-mixing spectroscopy

    Microsoft Academic Search

    Adrian A. Atherton; William G. Tong

    2005-01-01

    Ultrasensitive optical absorption detection method based on multi-photon wave-mixing spectroscopy is inherently suitable for biochips, biosensors and microarrays. Absorption-based wave mixing offers detection sensitivity levels that are comparable or better than those of fluorescence-based methods while using micrometer-thin samples. Wave-mixing methods offer detection of biospecific interactions on antibody or oligonucleotide microarray platforms. Optical absorption measurements of protein and DNA profiles

  10. Multi-photon, multi-mode polarization entanglement in parametric down-conversion

    E-print Network

    Gatti, A; Miguel, M S; Lugiato, L A; Gatti, Alessandra; Lugiato, Luigi A.; Miguel, Maxi San; Zambrini, Roberta

    2003-01-01

    We study the quantum properties of the polarization of the light produced in type II spontaneous parametric down-conversion in the framework of a multi-mode model valid in any gain regime. We show that the the microscopic polarization entanglement of photon pairs survives in the high gain regime (multi-photon regime), in the form of nonclassical correlation of all the Stokes operators describing polarization degrees of freedom.

  11. Multi-photon, multi-mode polarization entanglement in parametric down-conversion

    E-print Network

    Alessandra Gatti; Roberta Zambrini; Maxi San Miguel; Luigi A. Lugiato

    2003-06-19

    We study the quantum properties of the polarization of the light produced in type II spontaneous parametric down-conversion in the framework of a multi-mode model valid in any gain regime. We show that the the microscopic polarization entanglement of photon pairs survives in the high gain regime (multi-photon regime), in the form of nonclassical correlation of all the Stokes operators describing polarization degrees of freedom.

  12. The photoelectron spectrum of ArXe obtained using resonantly enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.

    1985-06-01

    The photoelectron spectrum of the heteronuclear rare gas dimer ArXe was determined using resonantly enhanced multiphoton ionization-photoelectron spectroscopy (REMPI-PES). Three photoelectron peaks are observed corresponding to the production of ArXe+ in the A2?+1/2 B2?3/2, and B2?1/2 states. The kinetic energies of these peaks are used to determine lower limits for the dissociation energies of the ionic states.

  13. Coupling CARS with multiphoton fluorescence and high harmonic generation imaging modalities using a femtosecond laser source

    Microsoft Academic Search

    Hongtao Chen; Mikhail N. Slipchenko; Jiabin Zhu; Kimberly K. Buhman; Ji-Xin Cheng

    2009-01-01

    Multimodal nonlinear optical imaging has opened new opportunities and becomes a powerful tool for imaging complex tissue samples with inherent 3D spatial resolution.. We present a robust and easy-to-operate approach to add the coherent anti-stokes Raman scattering (CARS) imaging modality to a widely used multiphoton microscope. The laser source composed of a Mai Tai femtosecond laser and an optical parametric

  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. Multiphoton ionization of a metastable hydrogen atom by electron and positron impact and charge asymmetry

    NASA Astrophysics Data System (ADS)

    Ghosh Deb, S.; Biswas, A.; Sinha, C.

    2011-11-01

    Charge asymmetry is studied theoretically for multiphoton ionization (n? e±, e e±) of a hydrogen atom from its metastable (2S) state using coplanar geometry. The external laser field is chosen to be single-mode, spatially homogeneous, linearly polarized with laser intensity that is quite high by laboratory standards. The continuum states of the impinging electron (e) or positron (e+) are represented by plane wave Volkov states, while the wavefunctions for the ejected electron and the scattered electron/positron are chosen to be of Coulomb-Volkov type. The dressed wavefunction for the metastable (2S) hydrogen is constructed in the framework of degenerate perturbation theory. Charge asymmetry is noted in the triple differential cross sections (TDCS) of the two projectiles both in the field-free (FF) and laser-assisted situations. The positron binary peak intensity is much higher than that of the electron, while the reverse is true for the recoil peak. As for the laser modifications, the single-photon TDCS exhibits a distinct four lobed structure in contrast to the FF (two lobed) and is highly suppressed w.r.t. the latter, while the multiphoton TDCS usually tends to approach the FF (with some exceptions), obeying the famous Kroll-Watson (KW) sum rule for both projectiles. For e+ impact, the electron capture to the continuum (ECC) effect is also studied (for the symmetric geometry), where enhancement is noted in both the single and multiphoton ECC peaks thereby deviating from the KW sum rules.

  16. Multiphoton effects in laser-assisted ionization of a helium atom by electron impact

    NASA Astrophysics Data System (ADS)

    Ghosh Deb, S.; Sinha, C.

    2010-11-01

    The dynamics of the electron impact multiphoton ionization of a He atom in the presence of an intense laser field ( n ? _e, 2 e) is studied theoretically for laser polarization (\\vert\\vert^l) and perpendicular (bot^r) to the incident momentum. The triple differential (TDCS) as well as the double differential (DDCS) cross sections are studied for the coplanar asymmetric geometry. The results are compared with the only available kinematically complete experiment at high incident energy (1000 eV). Significant laser modification (enhancement) is noted due to multiphoton effects in the present binary and recoil peak intensities of the TDCS for both the geometries, in qualitative agreement with the experiment. In the single photon case, the net effect of the laser field is to suppress the field free (FF) TDCS as well as the DDCS in the zeroth order approximation of the ejected electron wave function (CV), while in the first order (MCV), the cross sections are found to be enhanced. The CV multiphoton cross sections obey the famous Kroll Watson (KW) sum rule while the latter does not hold good in the corresponding MCV approximation.

  17. Multiphoton fluorescence imaging of NADH to quantify metabolic changes in epileptic tissue in vitro

    NASA Astrophysics Data System (ADS)

    Chia, Thomas H.; Zinter, Joseph; Spencer, Dennis D.; Williamson, Anne; Levene, Michael J.

    2007-02-01

    A powerful advantage of multiphoton microscopy is its ability to image endogenous fluorophores such as the ubiquitous coenzyme NADH in discrete cellular populations. NADH is integral in both oxidative and non-oxidative cellular metabolism. NADH loses fluorescence upon oxidation to NAD +; thus changes in NADH fluorescence can be used to monitor metabolism. Recent studies have suggested that hypo metabolic astrocytes play an important role in cases of temporal lobe epilepsy (TLE). Current theories suggest this may be due to defective and/or a reduced number of mitochondria or dysfunction of the neuronal-astrocytic metabolic coupling. Measuring NADH fluorescence changes following chemical stimulation enables the quantification of the cellular distribution of metabolic anomalies in epileptic brain tissue compared to healthy tissue. We present what we believe to be the first multiphoton microscopy images of NADH from the human brain. We also present images of NADH fluorescence from the hippocampus of the kainate-treated rat TLE model. In some experiments, human and rat astrocytes were selectively labeled with the fluorescent dye sulforhodamine 101 (SR101). Our results demonstrate that multiphoton microscopy is a powerful tool for assaying the metabolic pathologies associated with temporal lobe epilepsy in humans and in rodent models.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  19. Quantitative Analysis of Monocyte Subpopulations in Murine Atherosclerotic Plaques by Multiphoton Microscopy

    PubMed Central

    Haka, Abigail S.; Potteaux, Stephane; Fraser, Haley; Randolph, Gwendalyn J.; Maxfield, Frederick R.

    2012-01-01

    The progressive accumulation of monocyte-derived cells in the atherosclerotic plaque is a hallmark of atherosclerosis. However, it is now appreciated that monocytes represent a heterogeneous circulating population of cells that differ in functionality. New approaches are needed to investigate the role of monocyte subpopulations in atherosclerosis since a detailed understanding of their differential mobilization, recruitment, survival and emigration during atherogenesis is of particular importance for development of successful therapeutic strategies. We present a novel methodology for the in vivo examination of monocyte subpopulations in mouse models of atherosclerosis. This approach combines cellular labeling by fluorescent beads with multiphoton microscopy to visualize and monitor monocyte subpopulations in living animals. First, we show that multiphoton microscopy is an accurate and timesaving technique to analyze monocyte subpopulation trafficking and localization in plaques in excised tissues. Next, we demonstrate that multiphoton microscopy can be used to monitor monocyte subpopulation trafficking in atherosclerotic plaques in living animals. This novel methodology should have broad applications and facilitate new insights into the pathogenesis of atherosclerosis and other inflammatory diseases. PMID:23024767

  20. Cool Cosmos: Infrared Astronomy Tutorial

    NSDL National Science Digital Library

    NASA IPAC/CALTECH

    This Web site includes the following sections: Discovery of Infrared; What is Infrared?; Infrared Astronomy; Atmospheric Windows; Near, Mid & Far Infrared; IR Astronomy Timeline; Background & Technology; The Infrared Universe; Infrared Spectroscopy; News & Discoveries; and Images & Videos.

  1. Analysis of microparticle penetration into human and porcine skin: non-invasive imaging with multiphoton excitation microscopy

    Microsoft Academic Search

    William J. Mulholland; Mark A. Kendall; Brian J. Bellhouse; Nick White

    2002-01-01

    At the University of Oxford and PowderJect Pharmaceuticals plc, a unique form of needle-free injection technology has been developed. Powdered vaccines and drugs in micro-particle form are accelerated in a high-speed gas flow to sufficient velocity to enter the skin, subsequently achieving a pharmaceutical effect. To optimize the delivery of vaccines and drugs with this method a detailed understanding of

  2. Excitons in Cuprous Oxide: Photoionization and Other Multiphoton Processes

    NASA Astrophysics Data System (ADS)

    Frazer, Nicholas Laszlo

    In cuprous oxide (Cu2O), momentum from the absorption of two infrared photons to make an orthoexciton is conserved and detected through the photon component of a resulting mixed exciton/photon (quadrupole exciton polariton) state. I demonstrated that this process, which actually makes the photon momentum more precisely defined, is disrupted by photoionization of excitons. Some processes are known to affect exciton propagation in both the pump and exciton stages, such as phonon emission, exciton-exciton (Auger) scattering, and third harmonic generation. These processes alone were not able to explain all observed losses of excitons or all detected scattering products, which lead me to design an optical pump-probe experiment to measure the exciton photoionization cross section, which is (3.9+/-0.2) x 10-22 m2. This dissertation describes the synthesis of cuprous oxide crystals using oxidation of copper, crystallization from melt with the optical floating zone method, and annealing. The cuprous oxide crystals were characterized using time and space resolved luminescence, leading to the discovery of new defect properties. Selection rules and overall efficiency of third harmonic generation in these crystals were characterized. Exciton photoionization was demonstrated through the depletion of polariton luminescence by an optical probe, the production of phonon linked luminescence as a scattering product, temporal delay of the probe, and time resolved luminescence. The results are integrated with the traditional dynamical model of exciton densities. An additional investigation of copper/cuprous oxide/gold photovoltaic devices is appended.

  3. Near infrared lasers in flow cytometry.

    PubMed

    Telford, William G

    2015-07-01

    Technology development in flow cytometry has closely tracked laser technology, the light source that flow cytometers almost exclusively use to excite fluorescent probes. The original flow cytometers from the 1970s and 1980s used large water-cooled lasers to produce only one or two laser lines at a time. Modern cytometers can take advantage of the revolution in solid state laser technology to use almost any laser wavelength ranging from the ultraviolet to the near infrared. Commercial cytometers can now be equipped with many small solid state lasers, providing almost any wavelength needed for cellular analysis. Flow cytometers are now equipped to analyze 20 or more fluorescent probes simultaneously, requiring multiple laser wavelengths. Instrument developers are now trying to increase this number by designing fluorescent probes that can be excited by laser wavelength at the "edges" of the visible light range, in the near ultraviolet and near-infrared region. A variety of fluorescent probes have been developed that excite with violet and long wavelength ultraviolet light; however, the near-infrared range (660-800nm) has yet seen only exploitation in flow cytometry. Fortunately, near-infrared laser diodes and other solid state laser technologies appropriate for flow cytometry have been in existence for some time, and can be readily incorporated into flow cytometers to accelerate fluorescent probe development. The near infrared region represents one of the last "frontiers" to maximize the number of fluorescent probes that can be analyzed by flow cytometry. In addition, near infrared fluorescent probes used in biomedical tracking and imaging could also be employed for flow cytometry with the correct laser wavelengths. This review describes the available technology, including lasers, fluorescent probes and detector technology optimal for near infrared signal detection. PMID:25814439

  4. 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.

  5. Spectroscopic probes of vibrationally excited molecules at chemically significant energies

    SciTech Connect

    Rizzo, T.R.

    1993-04-01

    Infrared-optical double resonance is being used to study the unimolecular dissociation dynamics of hydrazoic acid (HN[sub 3]). 6[nu][sub NH] vibrational overtone excitation spectra are given for HN[sub 3]. Work was begun to determine the feasibility of extending the infrared-optical double resonance photofragment spectroscopy to small free radicals, and to be able to monitor atomic dissociation fragments via laser induced fluorescence in the VUV spectrum. 1 fig.

  6. Spectroscopic Infrared Ellipsometry

    E-print Network

    Eindhoven, Technische Universiteit

    Spectroscopic Infrared Ellipsometry: Components, Calibration, and Application #12;CIP-DATA KONINKLIJKE BIBLIOTHEEK, DEN HAAG Boer, Johannes Henricus Wilhelmus Gerardus den Spectroscopic Infrared in Dutch. ISBN 90 386 0017 8 Subject headings: spectroscopy ellipsometry infrared. #12;Spectroscopic

  7. Collisional effects in the multiphoton dissociation of CF2CFCl

    NASA Astrophysics Data System (ADS)

    Stone, James; Thiele, Everett; Goodman, Myron F.; Stephenson, John C.; King, David S.

    1980-09-01

    We report results of a combined experimental and theoretical study of the effects of collisions with an inert buffer gas, on the CO2 laser induced MPD of CF2CFCl to form CF2 and CFCl. Rates of formation of the primary product CF2 have been determined, in real time using the laser excited fluorescence technique, at four IR laser intensities (Imax = 35, 47, 73, 220 MW/cm2) and a range of argon buffer gas pressures (0?PAr?500 Torr). The experimental data clearly show the effects of collisional hole filling at low pressures and V-T collisional deactivation at higher (?100 Torr) pressures. We present a generally applicable theoretical model for collisional effects in MPD, in which two parameters (1/?, ?E) specify the collisional deactivation, two parameters (s,

  8. Jet cooled spectra of pyrrolobenzene and of pyrrolobenzonitrile: the nature of the excited states

    NASA Astrophysics Data System (ADS)

    Belau, Leonid; Haas, Yehuda; Rettig, Wolfgang

    2002-09-01

    The jet cooled fluorescence and resonance enhanced multiphoton ionization (REMPI) excitation spectra of pyrrolobenzene (PB) and pyrrolobenzonitrile (PBN) were recorded in the UV range. Fluorescence lifetimes and emission spectra were obtained upon excitation up to 2200 cm-1 above the 0-0 band. The data indicate that the emission is from the forbidden L b-type state, while the absorption spectrum in solution is dominated by the L a-type state. The energy gap between S 1 and S 2, in these molecules is very small (around 500 cm-1); at room temperature, hot bands of the more allowed L a-type transition are expected to dominate the absorption spectrum.

  9. ATOMIC AND MOLECULAR PHYSICS: Multiphoton ionization of the hydrogen atom exposed to circularly or linearly polarized laser pulses

    NASA Astrophysics Data System (ADS)

    Wang, Pei-Jie; He, Feng

    2009-12-01

    This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent Schrödinger equation. It finds that the ratio of the ionization probabilities by linearly and circularly polarized laser pulses varies with the numbers of absorbing photons. With the same laser intensity, the circularly polarized laser pulse favors to ionize the atom with more ease than the linearly polarized laser pulse if only two or three photons are necessary to be absorbed. For the higher order multiphoton ionization, the linearly polarized laser pulse has the advantage over circularly polarized laser pulse to ionize the atom.

  10. ATOMIC AND MOLECULAR PHYSICS: Coherent Phase Control of Multiphoton Ionization in Three-Level Ladder-Type System

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-An; Chen, Yu-Ting; Wang, Zu-Geng; Sun, Zhen-Rong

    2009-03-01

    We present the theoretical investigation of photoelectron spectroscopy resulting from the strong field induced multiphoton ionization in a typical three-level ladder-style system. Our theoretical results show that the photo-electron spectral structure can be alternatively steered by spectral phase modulation. This physical mechanism for strong field quantum control is explicitly exploited by the time-dependent dressed state population. It is concluded that the phase-shaped laser pulses can be used to selectively manipulate the multiphoton ionization process in complicated quantum systems.

  11. 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.

  12. Cavity-enhanced generation of pulsed nonclassical multi-photon states

    E-print Network

    Zavatta, Alessandro; Bellini, Marco

    2008-01-01

    We demonstrate the generation of highly-nonclassical states of light by cavity-enhanced parametric down-conversion in the pulsed regime. By locking the enhancement cavity length to that of a master picosecond mode-locked laser, pump pulses are recycled after interacting with the parametric crystal, and the intracavity pump intensity can thus coherently build up. The resulting increase in the parametric gain is probed with the conditional generation and tomographic analysis of two-photon Fock states. This technique may be readily applied in many different experimental setups where the generation of highly-nonclassical or entangled multi-photon states is required.

  13. Integrated structural and functional optical imaging combining spectral-domain optical coherence and multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Vinegoni, Claudio; Ralston, Tyler; Tan, Wei; Luo, Wei; Marks, Daniel L.; Boppart, Stephen A.

    2006-01-01

    An integrated microscope that combines different optical techniques for simultaneous imaging is demonstrated. The microscope enables spectral-domain optical coherence microscopy based on optical backscatter, and multiphoton microscopy for the detection of two-photon fluorescence and second harmonic generation signals. The unique configuration of this integrated microscope allows for the simultaneous acquisition of both anatomical (structural) and functional imaging information with particular emphasis for applications in the fields of tissue engineering and cell biology. In addition, the contemporary analysis of the spectroscopic features can enhance contrast by differentiating among different tissue components.

  14. Coherent Scattering of a Multiphoton Quantum Superposition by a Mirror BEC

    SciTech Connect

    De Martini, Francesco [Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 2, I-00185 Roma (Italy); Accademia Nazionale dei Lincei, Via della Lungara 10, I-00165 Roma (Italy); Sciarrino, Fabio [Accademia Nazionale dei Lincei, Via della Lungara 10, I-00165 Roma (Italy); Vitelli, Chiara [Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 2, I-00185 Roma (Italy); Cataliotti, Francesco S. [Dipartimento di Energetica and LENS, Universita di Firenze, via N. Carrara 1, I-50019 Sesto F.no (Italy)

    2010-02-05

    We present the proposition of an experiment in which the multiphoton quantum superposition consisting of Napprox =10{sup 5} particles generated by a quantum-injected optical parametric amplifier, seeded by a single-photon belonging to an Einstein-Podolsky-Rosen entangled pair, is made to interact with a mirror-Bose-Einstein condensate (BEC) shaped as a Bragg interference structure. The overall process will realize a macroscopic quantum superposition involving a microscopic single-photon state of polarization entangled with the coherent macroscopic transfer of momentum to the BEC structure, acting in spacelike separated distant places.

  15. 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.

  16. Experimental quantum teleportation and multiphoton entanglement via interfering narrowband photon sources

    SciTech Connect

    Yang Jian; Zhang Han; Peng Chengzhi; Chen Zengbing [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Bao Xiaohui [Physikalisches Institut der Universitaet Heidelberg, Philosophenweg 12, Heidelberg 69120 (Germany); Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chen Shuai; Pan Jianwei [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Physikalisches Institut der Universitaet Heidelberg, Philosophenweg 12, Heidelberg 69120 (Germany)

    2009-10-15

    In this paper, 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 techniques 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 multiphoton source will have applications in some advanced quantum communication protocols and linear optical quantum computation.

  17. Method of producing carbon-13 by multiphoton decomposition of c3f6

    SciTech Connect

    Hackett, P.A.; Nip, W.S.; Willis, C.

    1982-05-04

    A method of producing carbon-13 by multiphoton decomposition of C3F6, said material containing carbon-12 and carbon-13 isotopic species, comprising irradiating gaseous C3F6 in a reaction chamber at a pressure below 10 torr with a laser beam at a frequency in the range of 950 to 1020 wavenumbers and providing a minimum fluence of 1 joules per sq. Cm. And passing the material through a physical separation stage to obtain a 13C2F4 product.

  18. 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.

  19. In vivo imaging of unstained tissues using long gradient index lens multiphoton endoscopic systems

    PubMed Central

    Huland, David M.; Brown, Christopher M.; Howard, Scott S.; Ouzounov, Dimitre G.; Pavlova, Ina; Wang, Ke; Rivera, David R.; Webb, Watt W.; Xu, Chris

    2012-01-01

    We characterize long (up to 285 mm) gradient index (GRIN) lens endoscope systems for multiphoton imaging. We fabricate a portable, rigid endoscope system suitable for imaging unstained tissues, potentially deep within the body, using a GRIN lens system of 1 mm diameter and 8 cm length. The portable device is capable of imaging a ~200 µm diameter field of view at 4 frames/s. The lateral and axial resolution in water is 0.85 µm and 7.4 µm respectively. In vivo images of unstained tissues in live, anesthetized rats using the portable device are presented. These results show great promise for GRIN endoscopy to be used clinically. PMID:22567597

  20. 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