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1

THE INTRAMOLECULAR VIBRATIONAL ENERGY DISTRIBUTION OF INFRARED MULTIPHOTON EXCITED MOLECULES  

E-print Network

the intramolecular dynamics of infrared multiphoton excited molecules. Time-resolved spontaneous and coherent anti-Stokes Raman spectroscopy was employed to measure the energy distribution among vibrational modes immediately with English, I was depressed and lacked confidence. He encouraged me at that time, and has continued to give

Mazur, Eric

2

Infrared multiphoton excitation, dissociation and ionization of C 60  

NASA Astrophysics Data System (ADS)

We report the observation of mid-infrared multiphoton excitation, dissociation, and ionization of C 60 by shaped CO 2 laser pulses. The results are interpreted in the framework of the general statistical theory of infrared laser chemistry, adding some simple model assumptions. The observations on intensity- and fluence-dependent fragment ion distributions are consistent with a mechanism of vibrational preionization from energies exceeding the threshold for ionization by about a factor of 8.

Hippler, Michael; Quack, Martin; Schwarz, René; Seyfang, Georg; Matt, Sara; Märk, Tilmann

1997-10-01

3

Vibrationally excited carbon dioxide produced by infrared multiphoton pyrolysis  

SciTech Connect

Vibrationally excited CO/sub 2/ has been observed in the infrared multiphoton pyrolysis (IRMP) of some organic molecules. The pyrolysis was induced by a high-power, pulsed CO/sub 2/ TEA laser. The vibrational excitation of CO/sub 2/ was investigated by time-delayed, intracavity probing with a weak flash photolysis CO/sub 2/ laser. The molecules 2-oxetanone (..beta..-propiolactone), 3-butenoic acid (vinylacetic acid), and 2-oxopropanoic acid (pyruvic acid) were all shown to produce vibrationally excited CO/sub 2/ as one of the photofragments. The excitation involved the symmetric stretching mode, as well as the asymmetric stretching mode, of CO/sub 2/. The results provide information about the structural dynamics of each reaction as well as the geometry of the transition states. 7 references, 5 figures.

Colberg, M.R.; Watkins, R.J.; Krogh, O.D.

1984-06-21

4

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

PubMed Central

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

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

2013-01-01

5

Multiphoton excitation of fluorescent probes.  

PubMed

This introduction reviews the multiphoton excitation cross sections of extrinsic and intrinsic fluorophores, genetically engineered probes, and nanoparticles. We will review the known two-photon excitation cross sections of biological indicators and will discuss several related issues such as how to theoretically estimate and experimentally gauge the two-photon cross section of an indicator. We provide practical guides for experimentally estimating the excitation cross section. PMID:25734074

Xu, Chris; Zipfel, Warren R

2015-01-01

6

Multi-photon excitation microscopy  

Microsoft Academic Search

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

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

2006-01-01

7

Multi-photon excitation microscopy.  

PubMed

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

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

2006-01-01

8

Multi-photon excitation microscopy  

PubMed Central

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

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

2006-01-01

9

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

PubMed Central

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

Seemann, K.M.; Kuhn, B.

2014-01-01

10

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

SciTech Connect

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

Coffee, Ryan N.; Gibson, George N. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

2004-05-01

11

Controlled Damage in Thick Specimens by Multiphoton ExcitationV?  

PubMed Central

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

Galbraith, James A.; Terasaki, Mark

2003-01-01

12

Controlled damage in thick specimens by multiphoton excitation.  

PubMed

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

Galbraith, James A; Terasaki, Mark

2003-05-01

13

Infrared multiphoton dissociation of two perfluorobutenes  

E-print Network

Photofragment translational spectroscopy was used to examine the infrared multiphotondissociation of octafluoro-1-butene and octafluoro-2-butene. The predominant unimolecular reaction in octafluoro-1-butene at moderate laser fluences is cleavage...

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

1997-08-04

14

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

SciTech Connect

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)

Dai, H.L.

1981-04-01

15

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

NASA Astrophysics Data System (ADS)

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.

Riemann, Iris; Fischer, Peter; Koenig, Karsten

2004-09-01

16

Investigations of multiphoton excitation and ionization in a short range potential  

SciTech Connect

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

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

1989-02-01

17

13C isotope separation using multiphoton excitation of carbon monoxide  

NASA Astrophysics Data System (ADS)

We report a possible means to selectively isolate 13C from carbon monoxide (CO) exploiting multiphoton dissociation near 199 nm. At ?=199.363 nm we observed mass spectra with greater than 95% 13C+ ions produced from CO with normal isotopic abundance. The technique of velocity map ion imaging was applied to explore this effect. The complete mechanism for the 13C+ detection reads as follows: CO( X1? +)+h?? CO( a3? 1), CO( a3? 1)+h?? C( 1D2)+ O( 3P0), C( 1D2)+h?? C( 3P1), C( 3P1)+h?? C++ e-. We also report the molecular constants for the CO h 3? + state for 12CO(? 00=100 385 .5 cm-1, B=1.97 1 cm-1) .

Hansen, Nils; Wodtke, Alec M.

2002-04-01

18

Multiroute decomposition of complex molecules during IR multiphoton excitation  

SciTech Connect

The rate constant of ethanol laser-induced decomposition (LIP) under the influence of pulsed laser IR radiation was calculated, and the relative yield of products by various routes was determined. Processes taking place during the interpulse interval were considered and the concentration of molecules was designated. When decomposition was small in comparison with the rate of relaxation processes, a quasisteady-state distribution of excited molecules was established. The yields of decomposition product during a pulse and an interpulse interval were determined.

Al'minderov, V.V.; Milikh, G.M.; Pshezhetskii, S.Ya.; Trakhtenberg, L.I.

1988-01-01

19

Functional patterned multiphoton excitation deep inside scattering tissue  

NASA Astrophysics Data System (ADS)

Stochastic distortion of light beams in scattering samples makes in-depth photoexcitation in brain tissue a major challenge. A common solution for overcoming scattering involves adaptive pre-compensation of the unknown distortion. However, this requires long iterative searches for sample-specific optimized corrections, which is a problem when applied to optical neurostimulation where typical timescales in the system are in the millisecond range. Thus, photoexcitation in scattering media that is independent of the properties of a specific sample would be an ideal solution. Here, we show that temporally focused two-photon excitation with generalized phase contrast enables photoexcitation of arbitrary spatial patterns within turbid tissues with remarkable robustness to scattering. We demonstrate three-dimensional confinement of tailored photoexcitation patterns >200 µm in depth, both in numerical simulations and through brain slices combined with patch-clamp recording of photoactivated channelrhodopsin-2.

Papagiakoumou, Eirini; Bègue, Aurélien; Leshem, Ben; Schwartz, Osip; Stell, Brandon M.; Bradley, Jonathan; Oron, Dan; Emiliani, Valentina

2013-04-01

20

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

NASA Astrophysics Data System (ADS)

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.

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

2006-05-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

22

Generation of harmonics via multiphoton resonant excitation of hydrogenlike ions in an x-ray free-electron-laser field  

NASA Astrophysics Data System (ADS)

The coherent radiation spectrum of highly charged hydrogenlike ions in an intense x-ray free-electron-laser field is considered. The spectrum corresponding to harmonic generation in the resonant multiphoton excitation regime is investigated both analytically and numerically, arising from the Dirac Hamiltonian. The obtained analytical results are based on the generalized rotating wave approximation and are in good agreement with performed numerical calculations. Estimations show that one can achieve efficient generation of coherent hard x-ray radiation using multiphoton resonant excitation by appropriate x-ray pulses.

Avetissian, H. K.; Avchyan, B. R.; Mkrtchian, G. F.

2014-11-01

23

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

PubMed Central

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

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

24

Multi-photon excitation and ionization cross sections in atomic oxygen  

SciTech Connect

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

McGuire, E.J.

1985-01-01

25

Multiphoton excitation and photodynamic activity of macromolecular derivatized mTHPC  

NASA Astrophysics Data System (ADS)

Multiphoton excitation of photosensitizers in photodynamic therapy constitutes a promising approach, because of the increasing tissue penetration for longer wavelength of illumination. In this contribution the photodynamic activity of polyethylene glycol macromolecular derivatized mTHPC upon two-photon excitation is established. To test the photo- activity of the photosensitizer, human colon carcinoma cells, HCT-116, were incubated with 2 (mu) g/ml of mTHPC- CMPEG4 in the nutrition medium. Subsequent pulsed laser irradiation at 784 nm focused down on growing cell monolayers restricts cell vitality clearly within 24 hours after irradiation. To investigate whether an anoxic or euoxic energy transfer mechanism is involved, a uric acid assay was performed to test for the generation of singlet oxygen. Upon single-photon excitation mTHPC-CMPEG4 in TriPEG decomposed uric acid via the generation of singlet oxygen. Using femtosecond pulsed laser irradiation no decomposition of the uric acid was found, implying an anoxic energy transfer mechanism after tow-photon excitation. However, at present, we cannot exclude local hyperthermic effects in the cells containing the photosensitizer to contribute to the photodynamic activity upon two-photon excitation.

Schneider, Marc; Graschew, Georgi; Roelofs, Theo A.; Balanos, Evangelos; Rakowsky, Stefan; Sinn, Hanns-joerg; Schlag, Peter M.

2000-03-01

26

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

PubMed

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

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

2010-01-01

27

Characterization of erythromycin analogs by collisional activated dissociation and infrared multiphoton dissociation in a quadrupole ion trap  

Microsoft Academic Search

The effectiveness of two activation techniques, collision activated dissociation (CAD) and infrared multiphoton dissociation\\u000a (IRMPD), is compared for structural characterization of protonated and lithium-cationized macrolides and a series of synthetic\\u000a precursors in a quadrupole ion trap (QIT). Generally, cleavage of the glycosidic linkages attaching the sugars to the macrolide\\u000a ring and water losses constitute the major fragmentation pathways for most

Matthew C. Crowe; Jennifer S. Brodbelt; Brian J. Goolsby; Paul Hergenrother

2002-01-01

28

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

29

Infrared Multiphoton Dissociation of Peptide Cations in a Dual Pressure Linear Ion Trap Mass Spectrometer  

PubMed Central

A dual pressure linear ion trap mass spectrometer was modified to permit infrared multiphoton dissociation (IRMPD) in each of the two cells - the first a high pressure cell operated at nominally 5 × 10-3 Torr and the second a low pressure cell operated at nominally 3 × 10-4 Torr. When IRMPD was performed in the high pressure cell, most peptide ions did not undergo significant photodissociation; however, in the low pressure cell peptide cations were efficiently dissociated with less than 25 ms of IR irradiation regardless of charge state. IRMPD of peptide cations allowed the detection of low m/z product ions including the y1 fragments and immonium ions which are not typically observed by ion trap collision induced dissociation (CID). Photodissociation efficiencies of ~100% and MS/MS (tandem mass spectrometry) efficiencies of greater than 60% were observed for both multiply and singly protonated peptides. In general, higher sequence coverage of peptides was obtained using IRMPD over CID. Further, greater than 90% of the product ion current in the IRMPD mass spectra of doubly charged peptide ions was composed of singly charged product ions compared to the CID mass spectra in which the abundances of the multiply and singly charged product ions were equally divided. Highly charged primary product ions also underwent efficient photodissociation to yield singly charged secondary product ions, thus simplifying the IRMPD product ion mass spectra. PMID:19739654

Gardner, Myles W.; Smith, Suncerae I.; Ledvina, Aaron R.; Madsen, James A.; Coon, Joshua J.; Schwartz, Jae C.; Stafford, George C.; Brodbelt, Jennifer S.

2009-01-01

30

Vibrationally Excited HCN in the Luminous Infrared Galaxy NGC 4418  

NASA Astrophysics Data System (ADS)

Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of Tvib ? 230 K between the vibrational ground and excited (v 2 = 1) states. This excitation is most likely due to infrared radiation. At this high vibrational temperature the path through the v 2 = 1 state must have a strong impact on the rotational excitation in the vibrational ground level, although it may not be dominant for all rotational levels. Our observations also revealed nearly confusion-limited lines of CO, HCN, HCO+, H13CN, HC15N, CS, N2H+, and HC3N at ? ~ 1 mm. Their relative intensities may also be affected by the infrared pumping.

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

2010-12-01

31

Compact non-contact total emission detection for in vivo multiphoton excitation microscopy.  

PubMed

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

Combs, C A; Smirnov, A; Glancy, B; Karamzadeh, N S; Gandjbakhche, A H; Redford, G; Kilborn, K; Knutson, J R; Balaban, R S

2014-02-01

32

Combined infrared multiphoton dissociation and electron capture dissociation with a hollow electron beam in Fourier transform ion cyclotron resonance mass spectrometry  

Microsoft Academic Search

An electron injection system based on an indirectly heated ring-shaped dispenser cathode has been developed and installed in a 7 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spec- trometer. This new hardware design allows high-rate electron capture dissociation (ECD) to be car- ried out by a hollow electron beam coaxial with the ion cyclotron resonance (ICR) trap. Infrared multiphoton

Youri O. Tsybin; Matthias Witt; Frank Kjeldsen

2003-01-01

33

Current developments in clinical multiphoton tomography  

NASA Astrophysics Data System (ADS)

Two-photon microscopy has been introduced in 1990 [1]. 13 years later, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have been launched by the JenLab company with the tomograph DermaInspectTM. In 2010, the second generation of clinical multiphoton tomographs was introduced. The novel mobile multiphoton tomograph MPTflexTM, equipped with a flexible articulated optical arm, provides an increased flexibility and accessibility especially for clinical and cosmetical examinations. The multiphoton excitation of fluorescent biomolecules like NAD(P)H, flavins, porphyrins, elastin, and melanin as well as the second harmonic generation of collagen is induced by picojoule femtosecond laser pulses from an tunable turn-key near infrared laser system. The ability for rapid highquality image acquisition, the user-friendly operation of the system, and the compact and flexible design qualifies this system to be used for melanoma detection, diagnostics of dermatological disorders, cosmetic research, and skin aging measurements as well as in situ drug monitoring and animal research. So far, more than 1,000 patients and volunteers have been investigated with the multiphoton tomographs in Europe, Asia, and Australia.

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

2010-02-01

34

Structural characterization of the GM1 ganglioside by infrared multiphoton dissociation, electron capture dissociation, and electron detachment dissociation electrospray ionization FT-ICR MS\\/MS  

Microsoft Academic Search

Gangliosides play important biological roles and structural characterization of both the carbohydrate and the lipid moieties\\u000a is important. The FT-ICR MS\\/MS techniques of electron capture dissociation (ECD), electron detachment dissociation (EDD),\\u000a and infrared multiphoton dissociation (IRMPD) provide extensive fragmentation of the protonated and deprotonated GM1 ganglioside.\\u000a ECD provides extensive structural information, including identification of both halves of the ceramide and

Melinda A. McFarland; Alan G. Marshall; Christopher L. Hendrickson; Carol L. Nilsson; Pam Fredman; Jan-Eric Månsson

2005-01-01

35

Far-infrared excitations in rectangular antidot arrays  

Microsoft Academic Search

We have investigated far-infrared excitations in rectangular arrays of antidots in modulation-doped AlxGa1-xAs-GaAs heterostructures. In the rectangular antidot lattice the degeneracy of modes of a square array is lifted and a rich spectrum of higher-frequency modes is excited, particularly at small magnetic fields. These modes are sensitive to the direction of linear polarized radiation. Our experimental results are compared with

M. Hochgräfe; B. P. van Zyl; Ch. Heyn; D. Heitmann; E. Zaremba

2001-01-01

36

An exactly solvable model for multiphoton excitation of polyatomic molecules in the presence of collisions  

NASA Astrophysics Data System (ADS)

A theoretical study has been made on the non-stationary phenomena in the relaxation of highly vibrationally excited molecules under laser radiation giving rise to these molecules. An exact analytical solution to the master equation has been obtained in terms of Meixner polynomials with regard to VV and VT processes. The time-dependent vibrational distribution is used to obtain analytical expressions for the mean number of photons, stored on the vibrational degrees of freedom and transferred to a thermal bath. Using the latter result, an explicit expression is given for the average energy transfer as a function of time. Its dependence on the partial pressure of absorbing molecules has also been established.

Strekalov, M. L.

2013-11-01

37

Large excited state two photon absorptions in the near infrared region of surprisingly stable radical cations of (ferrocenyl)indenes.  

PubMed

Multiphoton absorptions are important non-linear optical processes which allow us to explore excited states with low energy photons giving rise to new possibilities for photoinduced processes. Among these processes, multiphoton absorptions from excited states are particularly interesting because of the large susceptibilities characteristic of excited states. Here we explore the nonlinear transmission measurements recorded with 9 ns laser pulses at 1064 nm of the radical cations of (2-ferrocenyl)indene and of (2-ferrocenyl)-hexamethylindene, two interesting very stable molecules. The non-linear transmission data can be interpreted with a multiphoton sequence of three photon absorptions, the first being a one photon absorption related to the intramolecular charge transfer and the second a two photon absorption from the excited state created with the first process. The two photon absorption cross section is found to be several orders of magnitude larger than those usually found for two photon absorbing systems excited from the ground state. PMID:23817723

Orian, Laura; Scuppa, Stefano; Santi, Saverio; Meneghetti, Moreno

2013-08-21

38

In vivo Drug Screening in Human Skin Using Femtosecond Laser Multiphoton Tomography  

Microsoft Academic Search

The novel femtosecond laser multiphoton imaging system DermaInspect forin vivotomography of human skin was used to study the diffusion and intradermal accumulation of topically applied cosmetic and pharmaceutical components. Near-infrared 80 MHz picojoule femtosecond laser pulses were employed to excite endogenous fluorophores and fluorescent components of a variety of ointments via a two-photon excitation process. In addition, collagen was imaged

K. König; A. Ehlers; F. Stracke; I. Riemann

2006-01-01

39

Quantum dynamics of molecular multiphoton excitation in intense laser and static electric fields: Floquet theory, quasienergy spectra, and application to the HF molecule  

E-print Network

The multiphoton excitationdynamics of vibration?rotation states in diatomic molecules in intense laser and static electric fields is investigated. The Floquet matrix method is used to calculate the quasienergy and multiphoton absorptionspectra...

Chu, Shih-I; Tietz, James V.; Datta, Krishna K.

1982-01-01

40

Multifocal multiphoton microscopy with adaptive optical correction  

NASA Astrophysics Data System (ADS)

Fluorescence lifetime imaging microscopy (FLIM) is a well established approach for measuring dynamic signalling events inside living cells, including detection of protein-protein interactions. The improvement in optical penetration of infrared light compared with linear excitation due to Rayleigh scattering and low absorption have provided imaging depths of up to 1mm in brain tissue but significant image degradation occurs as samples distort (aberrate) the infrared excitation beam. Multiphoton time-correlated single photon counting (TCSPC) FLIM is a method for obtaining functional, high resolution images of biological structures. In order to achieve good statistical accuracy TCSPC typically requires long acquisition times. We report the development of a multifocal multiphoton microscope (MMM), titled MegaFLI. Beam parallelization performed via a 3D Gerchberg-Saxton (GS) algorithm using a Spatial Light Modulator (SLM), increases TCSPC count rate proportional to the number of beamlets produced. A weighted 3D GS algorithm is employed to improve homogeneity. An added benefit is the implementation of flexible and adaptive optical correction. Adaptive optics performed by means of Zernike polynomials are used to correct for system induced aberrations. Here we present results with significant improvement in throughput obtained using a novel complementary metal-oxide-semiconductor (CMOS) 1024 pixel single-photon avalanche diode (SPAD) array, opening the way to truly high-throughput FLIM.

Coelho, Simao; Poland, Simon; Krstajic, Nikola; Li, David; Monypenny, James; Walker, Richard; Tyndall, David; Ng, Tony; Henderson, Robert; Ameer-Beg, Simon

2013-02-01

41

A New FRAP/FRAPa Method for Three-Dimensional Diffusion Measurements Based on Multiphoton Excitation Microscopy  

PubMed Central

We present a new convenient method for quantitative three-dimensionally resolved diffusion measurements based on the photobleaching (FRAP) or photoactivation (FRAPa) of a disk-shaped area by the scanning laser beam of a multiphoton microscope. Contrary to previously reported spot-photobleaching protocols, this method has the advantage of full scalability of the size of the photobleached area and thus the range of diffusion coefficients, which can be measured conveniently. The method is compatible with low as well as high numerical aperture objective lenses, allowing us to perform quantitative diffusion measurements in three-dimensional extended samples as well as in very small volumes, such as cell nuclei. Furthermore, by photobleaching/photoactivating a large area, diffusion along the optical axis can be measured separately, which is convenient when studying anisotropic diffusion. First, we show the rigorous mathematical derivation of the model, leading to a closed-form formula describing the fluorescence recovery/redistribution phase. Next, the ability of the multiphoton FRAP method to correctly measure absolute diffusion coefficients is tested thoroughly on many test solutions of FITC-dextrans covering a wide range of diffusion coefficients. The same is done for the FRAPa method on a series of photoactivatable green fluorescent protein solutions with different viscosities. Finally, we apply the method to photoactivatable green fluorescent protein diffusing freely in the nucleus of living NIH-3T3 mouse embryo fibroblasts. PMID:18621824

Mazza, Davide; Braeckmans, Kevin; Cella, Francesca; Testa, Ilaria; Vercauteren, Dries; Demeester, Jo; De Smedt, Stefaan S.; Diaspro, Alberto

2008-01-01

42

Probing excited states of NO involved in multistate interactions using the optical-optical double resonance-multiphoton ionization technique  

SciTech Connect

Many new transitions from the (3ssigma) A/sup 2/..sigma../sup +/ state to higher Rydberg and valence states in /sup 14/N/sup 16/O have been observed by the technique of optical-optical double resonance-multiphoton ionization. Upper states include members from the np, nd, nf Rydberg states (n = 3 to 6) and several vibrational levels of the B/sup 2/PI and L/sup 2/PI valence states. The spectral simplification aspect of the double resonance technique allows for the observation of these spectra without appreciable band overlap. Analysis of our data leads to the identification of several previously unobserved mixed Rydberg-valence vibrational levels. Discussions of the Rydberg-valence interactions in the 68,600-71,200-cm/sup -1/ energy region of /sup 14/N/sup 16/O are presented in light of these results. 31 references, 12 figures, 15 tables.

Cheung, W.Y.; Chupka, W.A.; Colson, S.D.; Gauyacq, D.; Avouris, P.; Wynne, J.J.

1986-03-13

43

Studies of protonated and anionic artemisinin in the gas-phase by infrared multi-photon dissociation and by negative ion photoelectron spectroscopies  

NASA Astrophysics Data System (ADS)

Protonated and anionic artemisinin in the gas phase have respectively been studied by infrared multi-photon dissociation (IRMPD) spectroscopy and by anion photoelectron spectroscopy. Comparison of the measured IRMPD spectrum with calculated spectra of various conformations showed that the two lowest-energy protonated structures, both corresponding to protonation at the C dbnd O 14 carbonyl site, were observed experimentally. The calculations also indicated that the peroxide bridge in artemisinin is only slightly modified by protonation. Additionally, stable, intact (parent) artemisinin radical anions have been obtained for the first time in the gas phase and the photoelectron spectrum supports the computational finding that the excess electron is mainly localized on the ? ? orbital of the peroxide bond. The vertical detachment energy and adiabatic electron affinity, calculated at the MP2/6-31+G ? level, are in good agreement with the experimental data and the O-O distance is calculated to be stretched by more than 50% in the anion.

Seydou, M.; Gillet, J. C.; Li, X.; Wang, H.; Posner, G. H.; Grégoire, G.; Schermann, J. P.; Bowen, K. H.; Desfrançois, C.

2007-12-01

44

Multiphoton excitation, ionization, and dissociation decay dynamics of small clusters of niobium tantalum, and tungsten - Time-resolved thermionic emission  

Microsoft Academic Search

The ionization dynamics of transition metal clusters have been investigated using time-of-flight mass and electron spectroscopy following single-photon (220 nm) and two-photon (351, 308, and 248 nm) excitation by pulsed laser light. At 220 nm, the ionization is direct and only prompt photoelectrons are produced. At 308 nm, delayed photoelectrons are produced. In consequence of this delayed ionization process, the

Andreas Amrein; Richard Simpson; Peter Hackett

1991-01-01

45

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

E-print Network

Infrared-active excitations related to Ho3+ ligand-field splitting at the commensurate-active excitations to electric-dipole transitions between ligand-field LF split states of Ho3+ ions. For light at T3=19 K. This effect shows a strong correlation with the pronounced steps of the b

Sirenko, Andrei

46

Quality control of food with near-infrared-excited Raman spectroscopy  

Microsoft Academic Search

The former considerable handicap of Raman spectroscopy in the visible range, the disturbing fluorescence of impurities, has now been eliminated: Raman spectra are excited by light quanta of the near-infrared range; their energy, however, is too small to excite fluorescence spectra. Now Raman spectroscopy can be applied to many ‘real world samples’, to quality control of raw material, to production

Stefan Keller; Thomas LiJchte; Bernd Dippel; Bernhard Schrader

1993-01-01

47

Cutaneous melanin exhibiting fluorescence emission under near-infrared light excitation  

Microsoft Academic Search

Under ultraviolet and visible light excitation, melanin is es- sentially a nonfluorescent substance. This work reports our study on near-infrared NIR fluorescence properties of melanins, and explores potential applications of NIR fluorescence techniques for evaluating skin disorders involving melanin. The NIR fluorescence spectrum is obtained using a fiber optic NIR spectrometer under 785-nm laser excitation. In vitro measurements are performed

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

2006-01-01

48

Optical biopsy of liver fibrosis by use of multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

49

Quantum dot infrared photodetector enhanced by surface plasma wave excitation  

E-print Network

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

Krishna, Sanjay

50

Multiphoton microscopy in life sciences  

Microsoft Academic Search

Summary Near infrared (NIR) multiphoton microscopy is becoming a novel optical tool of choice for fluorescence imaging with high spatial and temporal resolution, diagnostics, photo- chemistry and nanoprocessing within living cells and tissues. Three-dimensional fluorescence imaging based on non-resonant two-photon or three-photon fluorophor exci- tation requires light intensities in the range of MW cm22 to GW cm22, which can be

K. Konig

2000-01-01

51

Far-infrared observations of the exciting stars of Herbig-Haro objects. III - Circumstellar disks  

NASA Astrophysics Data System (ADS)

Far-infrared observations of the exciting stars of Herbig-Haro objects are presented that (1) show these stars to be of low luminosity; (2) indicate that it is not usual for these objects themselves to be visible at far-infrared wavelengths; and (3) demonstrate the existence of spatially resolved, physically large, potentially disklike structures. These latter structures are resolved perpendicular to the directions of flow from the stars, but not parallel to the flows. In addition to these general properties, two new HH-exciting stars were discovered by searching along the extrapolated proper motion vectors for these HHs; and the jetlike object 'DG Tau B' was also detected.

Cohen, M.; Harvey, P. M.; Schwartz, R. D.

1985-09-01

52

Far-infrared observations of the exciting stars of Herbig-Haro objects. III - Circumstellar disks  

NASA Technical Reports Server (NTRS)

Far-infrared observations of the exciting stars of Herbig-Haro objects are presented that (1) show these stars to be of low luminosity; (2) indicate that it is not usual for these objects themselves to be visible at far-infrared wavelengths; and (3) demonstrate the existence of spatially resolved, physically large, potentially disklike structures. These latter structures are resolved perpendicular to the directions of flow from the stars, but not parallel to the flows. In addition to these general properties, two new HH-exciting stars were discovered by searching along the extrapolated proper motion vectors for these HHs; and the jetlike object 'DG Tau B' was also detected.

Cohen, M.; Harvey, P. M.; Schwartz, R. D.

1985-01-01

53

Quasi white light multiphoton imaging  

NASA Astrophysics Data System (ADS)

We describe the realization and characterization of a broadband, high power density and fully spectrally controllable source, suitable for multiphoton imaging of biological samples. We used a photonic crystal fiber (PCF) with selected dispersive and non-linear properties, in order to generate, when pumped with <140 femtosecond pulses delivered by a tunable Ti:Sa laser (Chameleon Ultra II by Coherent Inc.), a smooth continuum in the 700nm-950nm region, with average power density grater than 2mW/nm. Time distribution of the generated spectrum has been measured with autocorrelation technique. Axial and lateral resolution obtained with a scanning multiphoton system has been determined to be near the theoretical limit. The possibility of two-photon excitation of different dyes in the same sample and high image resolution are demonstrated at tens of microns in depth. Future developments and different applications are also discussed.

de Mauro, C.; Alfieri, D.; Arrigoni, M.; Armstrong, D.; Pavone, F. S.

2009-07-01

54

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

55

Ab initio study of the orientation effects in multiphoton ionization and high-order harmonic generation from the ground and excited electronic states of H{sub 2}{sup +}  

SciTech Connect

We present an ab initio three-dimensional (3D) calculation of multiphoton ionization (MPI) and high-order harmonic generation (HHG) of the hydrogen molecular ions subject to intense linearly polarized laser pulses. The orientation of the molecular axis with respect to the polarization of the laser field can be arbitrary. The numerical procedure involves the extension of the generalized pseudospectral (GPS) method for nonuniform spatial discretization of the Hamiltonian and wave functions and time propagation using the split-operator technique in the energy representation. The calculations were performed for the ground and two first excited electronic states of H{sub 2}{sup +} at the internuclear separation R=2.0 a.u. The laser pulse has a sine-squared envelope and contains 20 optical cycles with the wavelength 800 nm. The dependence of MPI and HHG on the orientation angle is analyzed. We show that orientation effects are strongly affected by the symmetry of the wave function and the corresponding distribution of the electron density. While the anisotropy of MPI and HHG is rather weak for the 1{sigma}{sub g} state, both processes are suppressed at the orientation angle 90 deg. for the 1{sigma}{sub u} state and at the angle 0 deg. for the 1{pi}{sub u} state. We discuss the multiphoton resonance and two-center interference effects in the HHG spectra which can lead both to enhancement and suppression of the harmonic generation.

Telnov, Dmitry A.; Chu, Shih-I [Department of Chemistry, University of Kansas, Lawrence, Kansas 66045 (United States)

2007-10-15

56

FDTD\\/TDSE study on surface-enhanced infrared absorption by metal nanoparticles  

Microsoft Academic Search

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.

Shih-Hui Chang; George C. Schatz; Stephen K. Gray

2006-01-01

57

Multiphoton processes: conference proceedings  

SciTech Connect

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

Lambropoulos, P.; Smith, S.J. (eds.)

1984-01-01

58

[Application of nanophosphors with near infrared excitation for biomedical imaging].  

PubMed

Fluorescence bioimaging is an inevitable method for biological, medical and pharmaceutical sciences to visualize substances in biological objects in a highly sensitive, multicolor and dynamic way. Recently, elongation of the fluorescence wavelength is a trend used in this imaging to suppress scattering, which limits the imaging depth to within several millimeters. It has been known that the so-called "biological window" with low loss for a biological tissue has been known to lie in the near-infrared (NIR) wavelength range between 1000 and 1700 nm. The use of fluorescence in the over-1000-nm (OTN) NIR can deepen the observation to several centimeters. The use of imaging devices based on semiconductor silicon has limited the wavelength of the fluorescence bioimaging to less than 1000 nm. However, the appearance of InGaAs CCD on the market, to allow for imaging of the OTN-NIR light, is now changing the situation. On the other hand, rare-earth doped ceramic nanophosphors (RED-CNP) can emit efficient fluorescence in the OTN-NIR wavelength range. The author's group has applied the RED-CNP to OTN-NIR fluorescence bioimaging by hybridizing the RED-CNP with various polymers or molecules. The present paper will review the development of the materials and systems for this OTN-NIR fluorescence bioimaging, together with some applications of the imaging method for biological research and a medical surgery. PMID:23449415

Soga, Kohei

2013-01-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

60

Near-infrared resonant photoacoustic gas measurement using simultaneous dual-frequency excitation  

NASA Astrophysics Data System (ADS)

The simultaneous dual-frequency operation of a resonant photoacoustic gas sensor based on the differential mode excitation photoacoustic (DME-PA) technique is presented. The DME-PA method uses the excitation of two different modes in a resonant photoacoustic cell and the gas concentration is derived from the amplitude ratio of these acoustic modes. With the simultaneous dual-frequency excitation, the amplitude ratio needed by the DME-PA technique is obtained instantaneously, in contrast to the sequential modulation scheme where additional time delays are introduced by changing the modulation frequency. For a given excitation power reaching the photoacoustic cell, and a total acquisition time longer than 7 s, the simultaneous modulation scheme provides an improved measurement uncertainty compared to the sequential scheme. The proposed sensor allows measuring water vapour with a ±150 ppmV uncertainty using current-modulated near-infrared LEDs and a 15 s total acquisition time.

Rey, J. M.; Romer, C.; Gianella, M.; Sigrist, M. W.

2010-07-01

61

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser separation of oxygen isotopes by infrared multiphoton dissociation of CF3CH2OH  

Microsoft Academic Search

A study was made of isotopically selective multiphoton dissociation of 2,2,2-trifluoroethanol (CF3CH2OH) by radiation from a pulsed TEA CO2 laser. Enrichment of the dissociation product CO with 18O was observed. The maximum selectivity a approx 7.2 ± 1.5 and the dissociation yield of the target product (CF3CH218OH) beta18approx5% were obtained when the laser radiation frequency was omegalas = 1029.44 cm

Vladimir B. Laptev; Evgenii A. Ryabov; L. M. Tumanova

1989-01-01

62

Design of an infrared laser pulse to control the multiphoton dissociation of the Fe-CO bond in CO-heme compounds  

Microsoft Academic Search

Optimal control theory is used to design a laser pulse for the multiphoton dissociation of the Fe-CO bond in the CO-heme compounds. The study uses a hexacoordinated iron-porphyrin-imidazole-CO complex in its ground electronic state as a model for CO liganded to the heme group. The potential energy and dipole moment surfaces for the interaction of the CO ligand with the

Sitansh Sharma; Harjinder Singh; Jeremy N. Harvey; Gabriel G. Balint-Kurti

2010-01-01

63

On the nature of excited states of photosynthetic reaction centers: An ultrafast infrared study  

SciTech Connect

Bacterial photosynthetic reaction centers (RC) contain eight chromophores forming a well-defined supramolecular structure within a protein framework. Theoretical studies suggest that the excited states of these chromophores are delocalized and contain important contributions from charge-transfer and resonance states. There is no clear-cut experimental evidence pertaining to the degree of localization of excited states. We have used ultrafast near and mid-infrared spectroscopic methods to investigate the character of some of the excited states. Exciting the 800 nm, absorption band, we followed the fate of the excitation energy using either the stimulated emission of the special pair at 920 nm or a transient absorption at 1.2 {mu}m. For a completely localized system, Forster theory-based calculations are expected to accurately predict the kinetics of energy transfer. It was found, however, that calculated rates arc much faster than measured rates. This corroborates a delocalized picture, with internal conversion rather than energy transfer between states. We have also measured the transient absorption spectrum of the RC in the infrared spectral region, detecting several new low-lying electronic states. Assignments for these states, and implications for the localization problem will be discussed.

Haran, G.; Wynne, K.; Reid, G.D. [Univ. of Pennsylvania, Philadelphia, PA (United States)] [and others

1995-12-31

64

Multiphoton absorption in amyloid protein fibres  

NASA Astrophysics Data System (ADS)

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

Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

2013-12-01

65

Far-infrared laser magnetic resonance of vibrationally excited CD2  

NASA Technical Reports Server (NTRS)

The detection of 13 rotational transitions in the first excited bending state (010) of CD2 using the technique of far-infrared laser magnetic resonance spectroscopy is reported. Molecular parameters for this state are determined from these new data together with existing infrared observations of the v(2) band. Additional information on the ground vibrational state (000) is also provided by the observation of a new rotational transition, and this is combined with existing data to provide a refined set of molecular parameters for the CD2 ground state. One spectrum has been observed that is assigned as a rotational transition within the first excited symmetric stretching state (100) of CD2. These data will be of use in refining the structure and the potential function of the methylene radical.

Evenson, K. M.; Sears, T. J.; Mckellar, A. R. W.

1984-01-01

66

Two-photon-induced photoluminescence imaging of tumors using near-infrared excited gold nanoshells  

Microsoft Academic Search

We report strong two-photon-induced photoluminescence (TPIP) from silica\\/gold nanoshells (NS). We demonstrate its potential application for imaging the 3D distribution of NS in tumors using a NIR laser scanning multi-photon microscope.

Arnold Estrada; Kelly Sharp; Krystina Sang; Jon A. Schwartz; Danielle K. Smith; Chris Coleman; P. J. Donald; Brian A. Korgel; Andrew K. Dunn; James W. Tunnell

2008-01-01

67

Cell assay using a two-photon-excited europium chelate  

PubMed Central

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

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

2011-01-01

68

Clinical multiphoton and CARS microscopy  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

69

Multiphoton absorption is probably not the primary threshold damage mechanism for femtosecond laser pulse exposures in the retinal pigment epithelium  

NASA Astrophysics Data System (ADS)

Laser induced breakdown has the lowest energy threshold in the femtosecond domain, and is responsible for production of threshold ocular lesions. It has been proposed that multiphoton absorption may also contribute to ultrashort-pulse tissue damage, based on the observation that 33 fs, 810 nm pulse laser exposures caused more DNA breakage in cultured, primary RPE cells, compared to CW laser exposures delivering the same average power. Subsequent studies, demonstrating two-photon excitation of fluorescence in isolated RPE melanosomes, appeared to support the role of multiphoton absorption, but mainly at suprathreshold irradiance. Additional experiments have not found a consistent difference in the DNA strand breakage produced by ultrashort and CW threshold exposures. DNA damage appears to be dependent on the amount of melanin pigmentation in the cells, rather than the pulsewidth of the laser; current studies have found that, at threshold, CW and ultrashort pulse laser exposures produce almost identical amounts of DNA breakage. A theoretical analysis suggest that the number of photons delivered to the RPE melanosome during a single 33-fsec pulse at the ED50 irradiance is insufficient to produce multiphoton excitation. This result appears to exclude the melanosome as a locus for two- or three-photon excitation; however, a structure with a larger effective absorption cross-section than the melanosome may interact with the laser pulses. One possibility is that the nuclear chromatin acts as a unit absorber of photons resulting in DNA damage, but this does not explain the near equivalence of ultrashort and CW exposures in the comet assay model. This equivalence indicated that multiphoton absorption is not a major contributor to the ultrashort pulse laser damage threshold in the near infrared.

Glickman, Randolph D.; Johnson, Thomas E.

2004-07-01

70

Multi-photon processes in alkali metal vapors  

NASA Astrophysics Data System (ADS)

Achieving population inversion through multi-photon cascade pumping is almost always difficult, and most laser medium work under 1-photon excitation mechanism. But for alkali atoms such as cesium, relatively large absorption cross sections of several low, cascading energy levels enable them properties such as up conversion. Here we carried out research on two-photon excitation alkali fluorescence. Two photons of near infrared region are used to excite alkali atoms to n 2 D5/2, n 2 D3/2 or higher energy levels, then the blue fluorescence of (n+1) 2 P3/2,(n+1) 2 P1/2-->n 2 S1/2 are observed. Different pumping paths are tried and by the recorded spectra, transition routes of cesium are deducted and concluded. Finally the possibility of two-photon style DPALs (diode pumped alkali laser) are discussed, such alkali lasers can give output wavelengths in the shorter end of visual spectroscopy (400-460 nm) and are expected to get application in underwater communication and material laser processing.

Gai, Baodong; Hu, Shu; Li, Hui; Shi, Zhe; Cai, Xianglong; Guo, Jingwei; Tan, Yannan; Liu, Wanfa; Jin, Yuqi; Sang, Fengting

2015-02-01

71

In vivo multiphoton tomography of inflammatory tissue and melanoma  

NASA Astrophysics Data System (ADS)

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.

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

2005-04-01

72

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

73

Multiphoton tomography of intratissue tattoo nanoparticles  

NASA Astrophysics Data System (ADS)

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

König, Karsten

2012-02-01

74

Characterizing lamina propria of human gastric mucosa by multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

75

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

PubMed Central

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

2015-01-01

76

Multispot multiphoton Ca²? imaging in acute myocardial slices.  

PubMed

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

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

2015-05-01

77

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

SciTech Connect

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

Valle, Jose J.; Eyler, John R.; Oomens, Jos; Moore, David T.; Meer, A.F.G. van der; Helden, Gert von; Meijer, Gerard; Hendrickson, Christopher L.; Marshall, Alan G.; Blakney, Gregory T. [Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200 (United States); FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN Nieuwegein (Netherlands); FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN Nieuwegein (Netherlands); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-4005 (United States); Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306 (United States); National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-4005 (United States)

2005-02-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

79

Two-photon-excited upconversion luminescence of Mn2+-doped germanate glass by infrared femtosecond laser irradiation  

NASA Astrophysics Data System (ADS)

We report on the upconversion luminescence of transition metal Mn ions doped germanate glass exited by an infrared femtosecond laser at room temperature. The luminescent spectra exhibited that the upconversion luminescence originates from the Mn2+ ions. The dependence of the fluorescence intensity on the pump power reveals that a two-photon excitation process dominates in the conversion of infrared radiation to the visible emission. It is suggested that the simultaneous absorption of two infrared photons produces the population of upper excited states, which leads to the characteristic visible emission. Furthermore, we observed that the photo-oxidation of Mn2+ ions to Mn3+ ions by measuring the absorption spectra of the Mn ions doped germanate glass before and after femtosecond laser irradiation.

Zhang, Yang; Li, Pengfei; Wang, Chengwei; Bao, Zongjie; Zhao, Quan-Zhong

2014-09-01

80

Fiber-based combined optical coherence and multiphoton endomicroscopy  

E-print Network

multiphoton microscopy (MPM) with Fourier domain optical coherence microscopy (OCM) is reported. The system is fused with a double-clad fiber device. The MPM and OCM share the same excitation light path in the core-clad fiber, respectively. The performance of the introduced double-clad device is analyzed. The device can

Chen, Zhongping

81

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

82

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

PubMed

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

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

2015-04-01

83

An interplay between infrared multiphoton dissociation Fourier-transform ion cyclotron resonance mass spectrometry and density functional theory computations in the characterization of a tripodal quinolin-8-olate Gd(III) complex.  

PubMed

A new hexadentate, tripodal 8-hydroxyquinoline based ligand (QH3) and its gadolinium(III) tris-chelated (GdQ) complex with hemicage structure was investigated by using high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). The protonated adduct of the free ligand and its hemicage tripodal Gd(III) complex, [GdQ + H](+), were first observed in experiments of electrospray ionization (ESI) with a linear ion trap (LTQ) mass spectrometer and further investigated by using high resolution FTICRMS. Gas-phase dissociation of the protonated Gd(III) complex, by infrared multiphoton dissociation (IRMPD) FTICR MS, demonstrated a fragmentation pattern with six main product cluster ions labeled as [Fn](+) (n = 1 up to 6). These product ions suggest the elimination of 7-amino-alkyl or 7-alkyl chains of the hemicage moiety. High resolution MS conditions allowed the elucidation of the fragmentation pattern and product ion structures along with the determination, among the isotopic pattern of Gd, of the chemical compositions of closely related species, which differ in terms of hydrogen content. Among the Gd six naturally stable isotopes, (158)Gd is the most abundant, and its peak within each cluster was used as a reference for distinguishing each product ions. Computational DFT investigations were applied to give support to some hypothesis of fragmentation pathways, which could not have been easily justified on the basis of the experimental work. Furthermore, computational studies suggested the coordination geometry of the protonated parent complex and the five- and four-coordinated complexes, which derive from its fragmentation. Furthermore, experimental and computational evidences were collected about the octet spin state of the parent compound. PMID:23436232

De Bonis, Margherita; Bianco, Giuliana; Amati, Mario; Belviso, Sandra; Cataldi, Tommaso R I; Lelj, Francesco

2013-04-01

84

An Interplay Between Infrared Multiphoton Dissociation Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry and Density Functional Theory Computations in the Characterization of a Tripodal Quinolin-8-Olate Gd(III) Complex  

NASA Astrophysics Data System (ADS)

A new hexadentate, tripodal 8-hydroxyquinoline based ligand (QH3) and its gadolinium(III) tris-chelated (GdQ) complex with hemicage structure was investigated by using high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). The protonated adduct of the free ligand and its hemicage tripodal Gd(III) complex, [GdQ + H]+, were first observed in experiments of electrospray ionization (ESI) with a linear ion trap (LTQ) mass spectrometer and further investigated by using high resolution FTICRMS. Gas-phase dissociation of the protonated Gd(III) complex, by infrared multiphoton dissociation (IRMPD) FTICR MS, demonstrated a fragmentation pattern with six main product cluster ions labeled as [Fn]+ ( n = 1 up to 6). These product ions suggest the elimination of 7-amino-alkyl or 7-alkyl chains of the hemicage moiety. High resolution MS conditions allowed the elucidation of the fragmentation pattern and product ion structures along with the determination, among the isotopic pattern of Gd, of the chemical compositions of closely related species, which differ in terms of hydrogen content. Among the Gd six naturally stable isotopes, 158Gd is the most abundant, and its peak within each cluster was used as a reference for distinguishing each product ions. Computational DFT investigations were applied to give support to some hypothesis of fragmentation pathways, which could not have been easily justified on the basis of the experimental work. Furthermore, computational studies suggested the coordination geometry of the protonated parent complex and the five- and four-coordinated complexes, which derive from its fragmentation. Furthermore, experimental and computational evidences were collected about the octet spin state of the parent compound.

De Bonis, Margherita; Bianco, Giuliana; Amati, Mario; Belviso, Sandra; Cataldi, Tommaso R. I.; Lelj, Francesco

2013-04-01

85

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

86

Excitation of Extended Red Emission and Near-Infrared Continuum Radiation in the Interstellar Medium  

NASA Astrophysics Data System (ADS)

Many small molecules including carbon clusters emit blackbody radiation in the visible spectrum when their internal temperature, T, is raised above 2000 K by photoabsorption. Blackbody emission is known to be the dominant cooling mechanism for small dehydrogenated carbon molecules for 1500 < T < 3000 K. The condition that T > 2000 K would be met by interstellar molecules containing <=28 carbon atoms, heated by energetic photons from the interstellar radiation field. It is shown here that thermal emission will augment photoluminescent emission in extended red emission (ERE) sources when the UV radiation field is enhanced. In particular, this mechanism provides a simple explanation for observations that show that only stars with T eff > 7000 K excite the ERE. The observation by Witt et al. that photons with energies >10.5 eV are required for the onset of ERE emission can then be interpreted as the condition for the initiation of thermal emission at visible wavelengths. These observational requirements have been combined with laboratory and theoretical data to constrain the emitters of the ERE to dehydrogenated carbon molecules, C N with 20 <= N <= 28 atoms. The composition and structure of these molecules is discussed and IR band energies for several possible C N species are provided. These molecules are stable against photodissociation in the interstellar radiation field. It is also shown that dimers of these molecules, (C N )2, may be the species that give rise to the near-infrared continuum first detected by Sellgren. A new effect that might be significant under interstellar conditions involving unimolecular rearrangement reactions in thermally excited molecules is also discussed.

Duley, W. W.

2009-11-01

87

EXCITATION OF EXTENDED RED EMISSION AND NEAR-INFRARED CONTINUUM RADIATION IN THE INTERSTELLAR MEDIUM  

SciTech Connect

Many small molecules including carbon clusters emit blackbody radiation in the visible spectrum when their internal temperature, T, is raised above 2000 K by photoabsorption. Blackbody emission is known to be the dominant cooling mechanism for small dehydrogenated carbon molecules for 1500 < T < 3000 K. The condition that T > 2000 K would be met by interstellar molecules containing <=28 carbon atoms, heated by energetic photons from the interstellar radiation field. It is shown here that thermal emission will augment photoluminescent emission in extended red emission (ERE) sources when the UV radiation field is enhanced. In particular, this mechanism provides a simple explanation for observations that show that only stars with T {sub eff} > 7000 K excite the ERE. The observation by Witt et al. that photons with energies >10.5 eV are required for the onset of ERE emission can then be interpreted as the condition for the initiation of thermal emission at visible wavelengths. These observational requirements have been combined with laboratory and theoretical data to constrain the emitters of the ERE to dehydrogenated carbon molecules, C {sub N} with 20 <= N <= 28 atoms. The composition and structure of these molecules is discussed and IR band energies for several possible C{sub N} species are provided. These molecules are stable against photodissociation in the interstellar radiation field. It is also shown that dimers of these molecules, (C{sub N} ){sub 2}, may be the species that give rise to the near-infrared continuum first detected by Sellgren. A new effect that might be significant under interstellar conditions involving unimolecular rearrangement reactions in thermally excited molecules is also discussed.

Duley, W. W., E-mail: wwduley@uwaterloo.c [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada)

2009-11-01

88

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

PubMed

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

König, K

2000-08-01

89

High-resolution multimodal clinical multiphoton tomography of skin  

NASA Astrophysics Data System (ADS)

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.

König, Karsten

2011-03-01

90

Ab initio design of picosecond infrared laser pulses for controlling vibrational-rotational excitation of CO molecules  

Microsoft Academic Search

Optimal control of rovibrational excitations of the CO molecule using picosecond infrared laser pulses is described in the framework of the electric-nuclear Born-Oppenheimer approximation [G. G. Balint-Kurti et al., J. Chem. Phys. 122, 084110 (2005)]. The potential energy surface of the CO molecule in the presence of an electric field is calculated using coupled cluster theory with a large orbital

Thomas Herrmann; Qinghua Ren; Gabriel G. Balint-Kurti; Frederick R. Manby

2007-01-01

91

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

PubMed

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

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

2014-09-15

92

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

E-print Network

) 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

Chu, Shih-I

93

Fourier Transform Raman Spectroscopy of Photoactive Proteins with Near-Infrared Excitation  

E-print Network

The Fourier transform (FT) Raman spectroscopic treatment of the photoactive proteins bacteriorhodopsin and the photosynthetic reaction center is reported, with excitation at 1.06 ?m. Excitation at this wavelength circumvents the limitations...

Johnson, Carey K.; Rubinovitz, Ronald

1990-07-01

94

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

NASA Astrophysics Data System (ADS)

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)

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

95

Quantitative determination of maximal imaging depth in all-NIR multiphoton microscopy images of thick tissues  

NASA Astrophysics Data System (ADS)

We report two methods for quantitatively determining maximal imaging depth from thick tissue images captured using all-near-infrared (NIR) multiphoton microscopy (MPM). All-NIR MPM is performed using 1550 nm laser excitation with NIR detection. This method enables imaging more than five-fold deep in thick tissues in comparison with other NIR excitation microscopy methods. In this study, we show a correlation between the multiphoton signal along the depth of tissue samples and the shape of the corresponding empirical probability density function (pdf) of the photon counts. Histograms from this analysis become increasingly symmetric with the imaging depth. This distribution transitions toward the background distribution at higher imaging depths. Inspired by these observations, we propose two independent methods based on which one can automatically determine maximal imaging depth in the all-NIR MPM images of thick tissues. At this point, the signal strength is expected to be weak and similar to the background. The first method suggests the maximal imaging depth corresponds to the deepest image plane where the ratio between the mean and median of the empirical photon-count pdf is outside the vicinity of 1. The second method suggests the maximal imaging depth corresponds to the deepest image plane where the squared distance between the empirical photon-count mean obtained from the object and the mean obtained from the background is greater than a threshold. We demonstrate the application of these methods in all-NIR MPM images of mouse kidney tissues to study maximal depth penetration in such tissues.

Sarder, Pinaki; Akers, Walter J.; Sudlow, Gail P.; Yazdanfar, Siavash; Achilefu, Samuel

2014-02-01

96

Infrared  

NASA Astrophysics Data System (ADS)

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

Vollmer, M.

2013-11-01

97

Broadband infrared and Raman probes of excited-state vibrational molecular dynamics; Simulation protocols based on loop diagrams  

PubMed Central

Vibrational motions in electronically excited states can be observed by either time and frequency resolved infrared absorption or by off resonant stimulated Raman techniques. Multipoint correlation function expressions are derived for both signals. Three representations for the signal which suggest different simulation protocols are developed. These are based on the forward and the backward propagation of the wavefunction, sum over state expansion using an effective vibration Hamiltonian and a semiclassical treatment of a bath. We show that the effective temporal (?t) and spectral (??) resolution of the techniques is not controlled solely by experimental knobs but also depends on the system dynamics being probed. The Fourier uncertainty ???t > 1 is never violated. PMID:23783120

Dorfman, Konstantin E.; Fingerhut, Benjamin P.; Mukamel, Shaul

2013-01-01

98

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

PubMed

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

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

2012-07-01

99

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

PubMed Central

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

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

2015-01-01

100

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

PubMed Central

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

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

2009-01-01

101

Laser action in chromium-activated forsterite for near infrared excitation  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

102

Photosensitizer-doped conjugated polymer nanoparticles with high cross-sections for one- and two-photon excitation  

NASA Astrophysics Data System (ADS)

We report a novel nanoparticle that is promising for photodynamic therapy applications, which consists of a ?-conjugated polymer doped with a singlet oxygen photosensitizer. The nanoparticles exhibit highly efficient collection of excitation light due to the large excitation cross-section of the polymer. A quantum efficiency of singlet oxygen production of 0.5 was determined. Extraordinarily large two-photon excitation cross-sections were determined, indicating promise for near infrared multiphoton photodynamic therapy. Gel electrophoresis of DNA after near-UV irradiation in the presence of nanoparticles indicated both purine base and backbone DNA damage.We report a novel nanoparticle that is promising for photodynamic therapy applications, which consists of a ?-conjugated polymer doped with a singlet oxygen photosensitizer. The nanoparticles exhibit highly efficient collection of excitation light due to the large excitation cross-section of the polymer. A quantum efficiency of singlet oxygen production of 0.5 was determined. Extraordinarily large two-photon excitation cross-sections were determined, indicating promise for near infrared multiphoton photodynamic therapy. Gel electrophoresis of DNA after near-UV irradiation in the presence of nanoparticles indicated both purine base and backbone DNA damage. Electronic supplementary information (ESI) available: Fluorescence lifetime determination, AFM particle height histogram, and gel electrophoresis details. See DOI: 10.1039/c0nr00834f

Grimland, Jennifer L.; Wu, Changfeng; Ramoutar, Ria R.; Brumaghim, Julia L.; McNeill, Jason

2011-04-01

103

Quantitative multiphoton imaging  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

104

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

PubMed Central

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

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

2014-01-01

105

Evaluation of Barrett Esophagus by Multiphoton Microscopy  

PubMed Central

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

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

2014-01-01

106

Sequencing of O-Glycopeptides Derived from an S-Layer Glycoprotein of Geobacillus stearothermophilus NRS 2004/3a Containing up to 51 Monosaccharide Residues at a Single Glycosylation Site by Fourier Transform Ion Cyclotron Resonance Infrared Multiphoton Dissociation Mass Spectrometry  

PubMed Central

The microheterogeneity of large sugar chains in glycopeptides from S-layer glycoproteins containing up to 51 monosaccharide residues at a single O-attachment site on a 12 amino acid peptide backbone was investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). Structural elucidation of glycopeptides with the same amino acid sequence and different glycoforms, having such a high saccharide-to-peptide ratio, was achieved by applying infrared multiphoton dissociation (IRMPD) MS/MS for the first time. A 100% sequence coverage of the glycan chain and a 50% coverage of the peptide backbone fragmentation were obtained. The microheterogeneity of carbohydrate chains at the same glycosylation site, containing largely rhamnose, could have been reliably assessed. PMID:17378537

Schaffer, Christina; Messner, Paul; Mormann, Michael; Peter-Katalini?, Jasna

2015-01-01

107

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

108

Multiphoton detachment from negative ions  

NASA Astrophysics Data System (ADS)

We have carried out extensive calculations of multiphoton detachment from negative halogen ions. Comparison between various levels of approximation as well as confrontation with experimental data show that the plane wave approximation allows one to obtain workable estimates of cross sections and atomic quantities accessible to experiment. The results obtained can be used as a guide to choose interesting experimental situations. However, it is clear that the plane wave approximation is only a first step in the theoretical investigation of multiphoton detachment from negative ions and should be followed by more accurate studies including a treatment of electron correlations both in the ground state and in continuum states.

Crance, Michèle

109

Advances in multiphoton microscopy technology  

PubMed Central

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

Hoover, Erich E.; Squier, Jeff A.

2013-01-01

110

Enhancement of terahertz radiation by CW infrared laser excitation in a doubly interdigitated grating gates transistors  

NASA Astrophysics Data System (ADS)

We report on a broadband terahertz emission from a doubly interdigitated grating gates high electron mobility transistor. The observed emission was explained as due to the excitation of multi mode of plasmons: thermally excited incoherent modes and instability-driven coherent modes. The experiment was performed using Fourier spectrometer system coupled with high sensitive 4K Silicon bolometer under the vacuum. To enhance the efficiency, the device was subjected, from the backside, to a CW 1.5 ?m laser beam. Dependence of the emission on the gate bias was observed and interpreted as due to the self-oscillation of the plasma waves.

Meziani, Y. M.; Nishimura, T.; Tsuda, H.; Suemitsu, T.; Knap, W.; Popov, V. V.; Otsuji, T.

2009-11-01

111

Design of infrared laser pulses for the deexcitation of highly excited homonuclear diatomic molecules  

Microsoft Academic Search

We explore the possibility of using shaped infrared laser pulses to deexcite a homonuclear diatomic molecule from its highest vibrational state down to its ground vibrational state. The motivation for this study arises from the need to deexcite alkali metal dimers in a similar way so as to stabilize molecular Bose-Einstein condensates. We demonstrate that for the case of the

Qinghua Ren; Gabriel G. Balint-Kurti; Frederick R. Manby; Maxim Artamonov; Tak-San Ho; Herschel Rabitz

2006-01-01

112

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

SciTech Connect

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

Weiler, M.; Bartl, K.; Gerhards, M. [TU Kaiserslautern and Research Center Optimas, Fachbereich Chemie, Erwin-Schroedinger-Strasse 52, 67663 Kaiserslautern (Germany)

2012-03-21

113

Surface deactivation of vibrationally excited N2 studied using infrared titration combined with quantum cascade laser absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The wall de-excitation probability \\gamma_{N_{2}} of vibrationally excited nitrogen molecules was determined using infrared (IR) titration with CO, CO2 and N2O. Gas mixtures of N2 with 0.05-0.5% of CO (CO2 or N2O) were excited by a pulsed dc discharge at p = 133 Pa in a cylindrical discharge tube. During the afterglow, the vibrational relaxation of titrating molecules was monitored in situ with quantum cascade laser absorption spectroscopy. The value of \\gamma _{N_{2}} was deduced from measured vibrational relaxation times using a model of vibrational kinetics in N2. It was found that adsorption of IR tracers on the surface may increase the value of \\gamma _{N_{2}} by a factor up to two, depending on the molecule and the surface material. It was demonstrated that N2O is the most inert and reliable tracer and it was used for the determination of \\gamma_{N_{2}} on silica, Pyrex, TiO2, Al2O3 and anodized aluminum. Pretreatment of the silica surface by low-pressure plasma was found to have a strong effect on the vibrational de-excitation. Values of \\gamma_{N_{2}} measured after O2, Ar and N2 plasma pretreatment of the same silica discharge tube were 5.7 × 10-4, 8.2 × 10-4 and 11 × 10-4, respectively. This study clearly demonstrates that the presence of adsorbed atoms and molecules on the surface may significantly alter the value of \\gamma_{N_{2}} .

Marinov, D.; Lopatik, D.; Guaitella, O.; Ionikh, Y.; Röpcke, J.; Rousseau, A.

2014-01-01

114

Differentiation of normal and cancerous lung tissues by multiphoton imaging  

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

115

Simultaneous time and wavelength resolved spectroscopy under two-colour near infrared and terahertz excitation  

NASA Astrophysics Data System (ADS)

Time and wavelength resolved spectroscopy requires optical sources emitting very short pulses and a fast detection mechanism capable of measuring the evolution of the output spectrum as a function of time. We use table-top Ti:sapphire lasers and a free-electron laser (FEL) emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection. One of the major aspects of this setup is the synchronization of pulses from the two lasers which we describe in detail. Optical properties of the FEL pulses are studied by autocorrelation and electro-optic sampling measurements. We discuss the advantages of using this setup to perform photoluminescence quenching in semiconductor quantum wells and quantum dots. Carrier redistribution due to pulsed excitation in these heterostructures can be investigated directly. Sideband generation in quantum wells is also studied where the intense FEL pulses facilitate the detection of the otherwise weak nonlinear effect.

Bhattacharyya, J.; Wagner, M.; Zybell, S.; Winnerl, S.; Stehr, D.; Helm, M.; Schneider, H.

2011-10-01

116

Simultaneous time and wavelength resolved spectroscopy under two-colour near infrared and terahertz excitation.  

PubMed

Time and wavelength resolved spectroscopy requires optical sources emitting very short pulses and a fast detection mechanism capable of measuring the evolution of the output spectrum as a function of time. We use table-top Ti:sapphire lasers and a free-electron laser (FEL) emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection. One of the major aspects of this setup is the synchronization of pulses from the two lasers which we describe in detail. Optical properties of the FEL pulses are studied by autocorrelation and electro-optic sampling measurements. We discuss the advantages of using this setup to perform photoluminescence quenching in semiconductor quantum wells and quantum dots. Carrier redistribution due to pulsed excitation in these heterostructures can be investigated directly. Sideband generation in quantum wells is also studied where the intense FEL pulses facilitate the detection of the otherwise weak nonlinear effect. PMID:22047280

Bhattacharyya, J; Wagner, M; Zybell, S; Winnerl, S; Stehr, D; Helm, M; Schneider, H

2011-10-01

117

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

118

[measurement of optical density in infrared absorption maxima of oxygen molecules based on their photochemical activity upon direct laser excitation].  

PubMed

Generation of singlet oxygen upon excitation of oxygen molecules by infrared diode lasers has been studied in organic media (carbon tetrachloride and acetone) saturated by air under normal pressure and temperature. A new approach to analysis of the experimental data has been developed taking into account a degree of overlapping of the spectral bands of oxygen and laser radiation. Optical density, molar absorption coefficient and the cross section of light absorption were determined for the main absorption maxima of O2 at 765 and 1273 nm. The results are compared with the data of previous studies. A significance of the obtained results for elucidation of photophysics and photochemistry of oxygen molecules and investigation of biological action of laser radiation is discussed. PMID:25702475

2014-01-01

119

Do the Infrared Emission Features Need Ultraviolet Excitation? The PAH Model in UV-Poor Reflection Nebulae  

E-print Network

One of the major challenges to identification of the 3.3, 6.2, 7.7, 8.6, and 11.3um interstellar IR emission bands with polycyclic aromatic hydrocarbon (PAH) molecules has been the recent detection of these bands in regions with little UV illumination, since small, neutral PAH molecules have little or no absorption at visible wavelengths and therefore require UV photons for excitation. We show here that our "astronomical" PAH model, incorporating the experimental result that the visual absorption edge shifts to longer wavelength upon ionization and/or as the PAH size increases, can closely reproduce the observed infrared emission bands of vdB 133, a UV-poor reflection nebula. It is also shown that single-photon heating of ``astronomical'' PAHs in reflection nebulae near stars as cool as T_eff=3000K can result in observable emission at 6.2, 7.7, 8.6, and 11.3um. Illustrative mid-IR emission spectra are also calculated for reflection nebulae illuminated by cool stars with T_eff=3500, 4500, 5000K. These will allow comparison with future Space Infrared Telescope Facility (SIRTF) observations of vdB 135 (T_eff=3600K), vdB 47 (T_eff=4500K), and vdB 101 (T_eff=5000K). It is also shown that the dependence of the 12um IRAS emission relative to the total far-IR emission on the effective temperature of the exciting star is consistent with the PAH model expectation for 3000K < T_eff < 30000K.

Aigen Li; B. T. Draine

2002-01-04

120

Luminescence quenching of conductive Si nanocrystals via "Linkage emission": Hopping-like propagation of infrared-excited Auger electrons  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

121

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

SciTech Connect

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.

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

122

Many-photon excitation of spherically symmetric molecules in an infrared laser field by weakly forbidden DeltaR!=0, Deltan!=0 vibrational-rotational transitions  

Microsoft Academic Search

An analysis is made of a model of multistage excitation of triply degenerate vibrations of spherically symmetric molecules in a strong infrared laser field. This involves allowing for weakly forbidden DeltaR!=0, Deltan!=0 transitions. It is shown that as a result of these transitions, a system of up to several dozen multistage resonances is established within the absorption band. These resonances

I. N. Knyazev; V. V. Lobko

1980-01-01

123

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)

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.

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

1994-01-01

124

Measurement of molecular diffusion in solution by multiphoton fluorescence photobleaching recovery  

PubMed Central

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

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

1999-01-01

125

Femtosecond laser pulse optimization for multiphoton cytometry and control of fluorescence  

NASA Astrophysics Data System (ADS)

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.

Tkaczyk, Eric Robert

126

Differentiation of normal and cancerous lung tissues by multiphoton imaging  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

127

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

129

Time Resolved Infrared Emission from Vibrational Excited Acetylene Following Super Energy Transfer Collisions with Hot Hydrogen  

NASA Astrophysics Data System (ADS)

Can a molecule be activated with large amounts of energy transferred in a single collision between an atom and a molecule? If so, this type of collision will greatly affect molecular reactivity and equilibrium in systems including combustion where abundant hot atoms exist. Conventional expectation of translation to vibration (T-V) energy transfer is that probability decreases exponentially with energy transferred. We show, however, that in collisions between a pair of atom/molecule for which chemical reactions may occur, such as between a hyperthermal H atom and an ambient acetylene molecule, (T-V) energy transfer occurs with surprisingly high efficiency through chemical complex formation. Time-resolved infrared emission observations reveal that collisions between H atoms moving with 60 kcal/mole energy and acetylene molecules result in transfer of up to 70% of this energy into vibrational degrees of freedom. These experimental results are further supported by state of the art quasi-classical trajectory calculations performed by Bowman and coworkers.

Smith, J. M.; Nikow, M.; Dai, J. Ma Andh. L.

2013-06-01

130

New nonlinear optical processes in molecules at infrared frequencies  

NASA Astrophysics Data System (ADS)

This final report details progress in the study of optical nonlinearities in molecules at infrared wavelengths. The objectives have been to investigate the nonlinear optical properties of triply resonant and two photon or Raman resonant molecules. The techniques of third harmonic generation, multiphoton absorption, and degenerate four wave mixing have been used, with a CO2 TEA laser as the excitation source. An outstanding accomplishment has been the successful application of third harmonic generation techniques to study collisionless multiphoton excitation in sulfur hexafluoride. Depending on the excitation frequency, one or two-photon processes have been identified which deplete the population of the discrete vibrational energy levels into the quasi-continuum. Similar third harmonic generation experiments have yielded lower conversion efficiency in ammonia than in sulfur hexafluoride. Only a single rotational level in ammonia is found to be resonant, so the susceptibility is only minimally enhanced. A second area of work is the study of the two photon Raman resonant molecule CD4. Third harmonic generation results were obtained for CD4 at room and cryogenic temperatures. Problems of fundamental wavelength absorption were eliminated and the nonlinearity was enhanced at 193K.

Becker, M. F.

1982-02-01

131

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

PubMed

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

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

2015-04-01

132

Wavefront sensorless adaptive optics temporal focusing-based multiphoton microscopy  

PubMed Central

Temporal profile distortions reduce excitation efficiency and image quality in temporal focusing-based multiphoton microscopy. In order to compensate the distortions, a wavefront sensorless adaptive optics system (AOS) was integrated into the microscope. The feedback control signal of the AOS was acquired from local image intensity maximization via a hill-climbing algorithm. The control signal was then utilized to drive a deformable mirror in such a way as to eliminate the distortions. With the AOS correction, not only is the axial excitation symmetrically refocused, but the axial resolution with full two-photon excited fluorescence (TPEF) intensity is also maintained. Hence, the contrast of the TPEF image of a R6G-doped PMMA thin film is enhanced along with a 3.7-fold increase in intensity. Furthermore, the TPEF image quality of 1?m fluorescent beads sealed in agarose gel at different depths is improved. PMID:24940539

Chang, Chia-Yuan; Cheng, Li-Chung; Su, Hung-Wei; Hu, Yvonne Yuling; Cho, Keng-Chi; Yen, Wei-Chung; Xu, Chris; Dong, Chen Yuan; Chen, Shean-Jen

2014-01-01

133

Wavefront sensorless adaptive optics temporal focusing-based multiphoton microscopy.  

PubMed

Temporal profile distortions reduce excitation efficiency and image quality in temporal focusing-based multiphoton microscopy. In order to compensate the distortions, a wavefront sensorless adaptive optics system (AOS) was integrated into the microscope. The feedback control signal of the AOS was acquired from local image intensity maximization via a hill-climbing algorithm. The control signal was then utilized to drive a deformable mirror in such a way as to eliminate the distortions. With the AOS correction, not only is the axial excitation symmetrically refocused, but the axial resolution with full two-photon excited fluorescence (TPEF) intensity is also maintained. Hence, the contrast of the TPEF image of a R6G-doped PMMA thin film is enhanced along with a 3.7-fold increase in intensity. Furthermore, the TPEF image quality of 1?m fluorescent beads sealed in agarose gel at different depths is improved. PMID:24940539

Chang, Chia-Yuan; Cheng, Li-Chung; Su, Hung-Wei; Hu, Yvonne Yuling; Cho, Keng-Chi; Yen, Wei-Chung; Xu, Chris; Dong, Chen Yuan; Chen, Shean-Jen

2014-06-01

134

Multiphoton Quantum Optics and Quantum State Engineering  

Microsoft Academic Search

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

Fabio Dell' Anno; Silvio De Siena; Fabrizio Illuminati

135

Multiphoton quantum optics and quantum state engineering  

Microsoft Academic Search

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

Fabio Dell’Anno; Silvio De Siena; Fabrizio Illuminati

2006-01-01

136

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

PubMed Central

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

Yoder, Elizabeth J.

2008-01-01

137

In vivo microscopy of the mouse brain using multiphoton laser scanning techniques  

NASA Astrophysics Data System (ADS)

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

Yoder, Elizabeth J.

2002-06-01

138

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

PubMed Central

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

Yew, Elijah; Rowlands, Christopher

2014-01-01

139

Isotopically selective IR multiphoton dissociation of 1,3,5-trioxane  

NASA Astrophysics Data System (ADS)

Searching for oxygen-isotope selectivity, we investigated the infrared multiphoton dissociation of the formaldehyde trimer around 10 µm, in a range where the molecule has a degenerate and a non-degenerate CO stretch vibration and a degenerate CH2 deformation vibration. In the region of the two latter, the wavelength dependence of the dissociation yield exhibits sharp structures. They were assigned to n-photon resonances ( n = 2, 3, 5) by the help of the IR spectrum in the fundamental and overtone region. The O and C selectivities were very small (1.05) near the non-degenerate CO stretch band, but surprisingly large (2 4) in the CH2 deformation, which has no isotopic shift. The selectivity is not controlled by the first ( n-photon) excitation step, but only by a later step. Its assignment is attempted. The pressure dependence of the dissociation is peculiar: Only after an initial decrease, the yield exhibits the usual rise with pressure. We attribute the decrease to a relaxation which perturbs the two-photon resonance.

Churakov, V.; Fuss, W.

1996-02-01

140

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

SciTech Connect

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

Yoshida, Kyohei; Hachiya, Kan; Okumura, Kensuke; Mishima, Kenta; Inukai, Motoharu; Torgasin, Konstantin; Omer, Mohamed [Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan)] [Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Sonobe, Taro [Kyoto University Research Administration Office, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan)] [Kyoto University Research Administration Office, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Zen, Heishun; Negm, Hani; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki [Institute of Advanced Energy, Kyoto University, Gokasyo, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Gokasyo, Uji, Kyoto 611-0011 (Japan)

2013-10-28

141

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

NASA Astrophysics Data System (ADS)

Cancer morbidity and mortality is greatly reduced when the disease is diagnosed and treated early in its development. Tissue biopsies are the gold standard for cancer diagnosis, and an accurate diagnosis requires a biopsy from the malignant portion of an organ. Light, guided through a fiber optic probe, could be used to inspect regions of interest and provide real-time feedback to determine the optimal tissue site for biopsy. This approach could increase the diagnostic accuracy of current biopsy procedures. The studies in this thesis have characterized changes in tissue optical signals with carcinogenesis, increasing our understanding of the sensitivity of optical techniques for cancer detection. All in vivo studies were conducted on the dimethylbenz[alpha]anthracene treated hamster cheek pouch model of epithelial carcinogenesis. Multiphoton microscopy studies in the near infrared wavelength region quantified changes in tissue morphology and fluorescence with carcinogenesis in vivo. Statistically significant morphological changes with precancer included increased epithelial thickness, loss of stratification in the epithelium, and increased nuclear diameter. Fluorescence changes included a statistically significant decrease in the epithelial fluorescence intensity per voxel at 780 nm excitation, a decrease in the fluorescence lifetime of protein-bound nicotinamide adenine dinucleotide (NADH, an electron donor in oxidative phosphorylation), and an increase in the fluorescence lifetime of protein-bound flavin adenine dinucleotide (FAD, an electron acceptor in oxidative phosphorylation) with precancer. The redox ratio (fluorescence intensity of FAD/NADH, a measure of the cellular oxidation-reduction state) did not significantly change with precancer. Cell culture experiments (MCF10A cells) indicated that the decrease in protein-bound NADH with precancer could be due to increased levels of glycolysis. Point measurements of diffuse reflectance and fluorescence spectra in the ultraviolet to visible wavelength range indicated that the most diagnostic optical signals originate from sub-surface tissue layers. Optical properties extracted from these spectroscopy measurements showed a significant decrease in the hemoglobin saturation, absorption coefficient, reduced scattering coefficient and fluorescence intensity (at 400 nm excitation) in neoplastic compared to normal tissues. The results from these studies indicate that multiphoton microscopy and optical spectroscopy can non-invasively provide information on tissue structure and function in vivo that is related to tissue pathology.

Skala, Melissa Caroline

2007-12-01

142

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

SciTech Connect

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

Kanomata, Kensaku [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan and Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Ohba, Hisashi; Pungboon Pansila, P.; Ahmmad, Bashir; Kubota, Shigeru; Hirahara, Kazuhiro; Hirose, Fumihiko, E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

2015-01-01

143

Origin of near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+)co-doped fluorotellurite glasses under different excitations.  

PubMed

We report the near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+) co-doped fluorotellurite glasses under 980, 1550 and 800?nm excitations, respectively. Using a 980?nm laser diode pump, enhanced 1.5 and 2.7??m emissions from Er(3+):I13/2?(4)I15/2 and I11/2?(4)I13/2 transitions are observed, in which Yb(3+) ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb(3+) can also be used as an acceptor and intensive upconversion luminescence of around 1000?nm is achieved from Er(3+):I11/2?(4)I15/2 and Yb(3+): F5/2?(4)F7/2 transitions using 1550?nm excitation. In addition, the luminescence properties and variation trendency by 800?nm excitation is similar to that using 1550?nm excitation. The optimum Er(3+) and Yb(3+) ion ratio is 1:1.5 and excess Yb(3+) ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er(3+)/Yb(3+) co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells. PMID:25648651

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

2015-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

145

Optically induced superconductivity in striped La2-xBaxCuO4 by polarization-selective excitation in the near infrared  

NASA Astrophysics Data System (ADS)

We show that superconducting interlayer coupling, which coexists with and is depressed by stripe order in La1.885Ba0.115CuO4, can be enhanced by excitation with near-infrared laser pulses. For temperatures lower than Tc=13 K, we observe a blue shift of the equilibrium Josephson plasma resonance, detected by terahertz-frequency reflectivity measurements. Key to this measurement is the ability to probe the optical properties at frequencies as low as 150 GHz, detecting the weak interlayer coupling strengths. For T >Tc a similar plasma resonance, absent at equilibrium, is induced up to the spin-ordering temperature TSO?40 K. These effects are reminiscent but qualitatively different from the light-induced superconductivity observed by resonant phonon excitation in La1.675Eu0.2Sr0.125CuO6.5. Importantly, enhancement of the below-Tc interlayer coupling and its appearance above Tc are preferentially achieved when the near-infrared pump light is polarized perpendicular to the superconducting planes, likely due to more effective melting of stripe order and the less effective excitation of quasiparticles from the Cooper pair condensate when compared to in-plane excitation.

Nicoletti, D.; Casandruc, E.; Laplace, Y.; Khanna, V.; Hunt, C. R.; Kaiser, S.; Dhesi, S. S.; Gu, G. D.; Hill, J. P.; Cavalleri, A.

2014-09-01

146

Laser multiphoton ionization of aromatic molecules in nonpolar liquids  

NASA Astrophysics Data System (ADS)

The laser multiphoton ionization (MPI) of fluoranthene in tetramethylsilane (TMS) and of azulene in n-tridecane, n-pentane, 2,2,4,4-tetramethylpentane, TMS and tetramethyltin is reported. Three distinct types of MPI mechanisms have been identified: two-photon ionization, stepwise three-photon ionization and mixed two- and three-photon ionization. The stepwise three-photon process consists of two-photon excitation, relaxation to a lower lying excited state with a lifetime comparable to the laser pulse duration (for azulene this state is the S 2 while for fluoranthene both the S 1 and S 2 states) and subsequent ionization with the absorption of a third photon. The ionization threshold of azulene in each liquid has been determined and found to vary linearly with the V0 of the liquid.

Faidas, H.; Christophorou, L. G.

147

Fluorescence lifetime imaging with near-infrared dyes  

NASA Astrophysics Data System (ADS)

Near-infrared (NIR) dyes are used as fluorescence markers in small-animal imaging and in diffuse optical tomography of the human brain. In these applications it is important to know whether the dyes bind to proteins or other tissue constituents, and whether their fluorescence lifetimes depend on the targets they are bound to. Unfortunately, neither the lasers nor the detectors of commonly used confocal and multiphoton laser scanning microscopes allow for excitation and detection of NIR fluorescence. We therefore upgraded existing confocal TCSPC FLIM systems with NIR lasers and NIR sensitive detectors. In multiphoton systems we used the Ti:Sa laser as a one-photon excitation source in combination with an NIR-sensitive detector in the confocal beam path. We tested a number of NIR dyes in biological tissue. Some of them showed clear lifetime changes depending on the tissue structures they are bound to. We therefore believe that NIR FLIM can deliver supplementary information on the tissue constitution and on local biochemical parameters.

Becker, Wolfgang; Shcheslavskiy, Vladislav

2013-02-01

148

MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH  

SciTech Connect

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.

R. Graham; W. Chow

2003-05-01

149

New developments in multimodal clinical multiphoton tomography  

Microsoft Academic Search

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

Karsten König

2011-01-01

150

Multiphoton analysis of normal and diseased livers  

NASA Astrophysics Data System (ADS)

Diseases associated with the liver, a major internal organ, can lead to serious health problems. In this work, we present multiphoton images of normal and diseased liver specimens and we will characterize the changes to pathological liver specimens. In particular, we will focus on the physiological changes associated with liver fibrosis. Our results show that multiphoton microscopy is a useful technique for distinguishing normal and diseased liver tissues and that it has potential applications for in vivo diagnosis of liver diseases.

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

2005-03-01

151

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

NASA Astrophysics Data System (ADS)

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.

Lai, Zhenhua

152

Multiphoton dissociation of H2S by intense x-ray pulses from the Linac Coherent Light Source FEL  

NASA Astrophysics Data System (ADS)

We will report on sequential multiphoton ionization of H2S by intense pulses of x-rays from the LCLS free electron laser. Following L-shell excitation, fragmentation of the molecule is observed by Auger electron, photoelectron, and ion time-of-flight spectroscopy. Intensity dependent features in these spectra shed light on the dynamics of the dissociation process.

Murphy, Brendan; Fang, Li; Hoener, Matthias; Kukk, Edwin; Kanter, Elliot; Bozek, John; Berrah, Nora

2011-06-01

153

A waveguide reactor for IR multiphoton dissociation and its application to 13 C laser isotope separation  

Microsoft Academic Search

A waveguide reactor for infrared multiphoton dissociation reactions has been presented and applied to laser isotope separation of13C. The reactor is a sealed vessel containing a hollow waveguide for a CO2 laser, and the laser beam is condensed in the waveguide. The waveguide is a pipe of total-reflection glass or metal-coated glass with a funnelled inlet; it is 50 cm

H. Kojima; K. Uchida; Y. Takagi

1986-01-01

154

Isotopically selective IR multiphoton dissociation of 1,3,5-trioxane  

Microsoft Academic Search

Searching for oxygen-isotope selectivity, we investigated the infrared multiphoton dissociation of the formaldehyde trimer around 10 µm, in a range where the molecule has a degenerate and a non-degenerate CO stretch vibration and a degenerate CH2 deformation vibration. In the region of the two latter, the wavelength dependence of the dissociation yield exhibits sharp structures. They were assigned ton-photon resonances

V. Churakov; W. Fuss

1996-01-01

155

Multiphoton dressing of an anharmonic superconducting many-level quantum circuit  

NASA Astrophysics Data System (ADS)

We report on the investigation of a superconducting anharmonic multilevel circuit that is coupled to a harmonic readout resonator. We observe multiphoton transitions via virtual energy levels of our system up to the fifth excited state. The back-action of these higher-order excitations on our readout device is analyzed quantitatively and demonstrated to be in accordance with theoretical expectation. By applying a strong microwave drive we achieve multiphoton dressing within our anharmonic circuit which is dynamically coupled by a weak probe tone. The emerging higher-order Rabi sidebands and associated Autler-Townes splittings involving up to five levels of the investigated anharmonic circuit are observed. Experimental results are in good agreement with master-equation simulations.

Braumüller, Jochen; Cramer, Joel; Schlör, Steffen; Rotzinger, Hannes; Radtke, Lucas; Lukashenko, Alexander; Yang, Ping; Skacel, Sebastian T.; Probst, Sebastian; Marthaler, Michael; Guo, Lingzhen; Ustinov, Alexey V.; Weides, Martin

2015-02-01

156

DNA multiphoton absorption generates localized damage for studying repair dynamics in live cells.  

PubMed

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

Daddysman, Matthew K; Fecko, Christopher J

2011-11-01

157

Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation\\/emission mechanism, and the astrophysical implications  

Microsoft Academic Search

A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate

L. J. Allamandola; G. G. M. Tielens; J. R. Barker

1989-01-01

158

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

SciTech Connect

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

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

1982-01-01

159

Results and prospects of laser separation of oxygen isotopes by IR multiphoton dissociation of molecules  

Microsoft Academic Search

An experimental search was made for an initial oxygen compound suitable for laser separation of oxygen isotopes by IR multiphoton dissociation of molecules. Over ten molecules with C—O, Si—O, Cr=O, and C=O bonds were investigated. The excitation was provided by pulsed TEA CO2 laser radiation, and also by its second harmonic. Measurements were made of the dissociation yields of the

Vladimir B Laptev; Evgenii A Ryabov; L. M. Tumanova

1995-01-01

160

Multiphoton spectroscopy of X-NO (X=Kr, Xe, CH4) van der Waals molecules  

NASA Astrophysics Data System (ADS)

The vibronic spectroscopy of the van der Waals species KrNO, XeNO, and CH4NO has been investigated via mass-resolved multiphoton ionization (MPI) spectroscopy. Spectra are presented for the two-photon excited electronic transition of the various complexes associated with the C 2? (v=0) state of nitric oxide. Dissociation pathways are analyzed for XeNO, which appears at the Xe+ mass following MPI. Trends in bonding and spectroscopic constants are discussed.

Miller, John C.

1987-03-01

161

Fine tunable red-green upconversion luminescence from glass ceramic containing 5%Er3+:NaYF4 nanocrystals under excitation of two near infrared femtosecond lasers  

NASA Astrophysics Data System (ADS)

In this paper, we report fine tunable red-green upconversion luminescence of glass ceramic containing 5%Er3+: NaYF4 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 Er3+ ions interacting with two fs laser fields, and explain well the experimental results.

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

2014-08-01

162

Upconversion luminescence in Er3+ doped Ga10Ge25S65 glass and glass-ceramic excited in the near-infrared  

NASA Astrophysics Data System (ADS)

The infrared-to-visible frequency upconversion was investigated in Er3+-doped Ga10Ge25S65 glass and in the transparent glass-ceramic obtained by heat-treatment of the glass above its glass-transition temperature. Continuous-wave and pulsed lasers operating at 980 nm and 1480 nm were used as excitation sources. The green (2H11/2 ? 4I15/2; 4S3/2 ? 4I15/2) and red (4F9/2 ? 4I15/2) photoluminescence (PL) signals due to the Er3+ ions were characterized. The PL decay times were influenced by energy transfer among Er3+ ions, by cross-relaxation processes and by energy transfer from the Er3+ ions to the host material. The PL from the Er3+ ions hosted in the crystalline phase was distinguished only when the glass-ceramic was excited by the 1480 nm pulsed laser. The excitation pathways responsible for the green and red PL bands are discussed to explain the differences between the spectra observed under continuous-wave and pulsed excitation.

Lozano B., Whualkuer; de Araújo, Cid B.; Ledemi, Yannick; Messaddeq, Younes

2013-02-01

163

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

PubMed Central

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

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

2002-01-01

164

Low-level detection of metal atoms by multiphoton ionization in a low-pressure flame sampling gel  

Microsoft Academic Search

The authors are using a low-pressure sampling cell to extract species from an air\\/acetylene analytical burner. Single-color multiphoton ionization by a pulsed dye laser is used for the sensitive detection of atomic species in the cell. The dye laser excites one of the low-lying two-photon accessible states, and absorption of an additional photon efficiently ionizes the excited state. Excellent detection

Perry R. Blazewicz; William B. Whitten; J. Michael. Ramsey

1989-01-01

165

Measurements of multiphoton action cross sections for multiphoton microscopy  

PubMed Central

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

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

2014-01-01

166

Continuous-mode multi-photon filtering  

E-print Network

The purpose of this paper is to derive filtering equations for an arbitrary open quantum system driven by a light wavepacket in a continuous-mode multi-photon state. A continuous-mode multi-photon state is a state of a travelling wavepacket that contains a definite number of photons and is characterised by a temporal (or spectral) profile. After the interaction with the system, the output light is measured by means of homodyne detection or photodetection. Filters for both cases are derived in this paper. Unlike the vacuum or the coherent case, the annihilation operator of the light field acting on a multi-photon state changes the state by annihilating a photon, which makes the traditional filtering techniques inapplicable. To circumvent this difficulty, we adopt a non-Markovian embedding technique proposed in [20]} for the study of single-photon filtering problem. However, the multi-photon nature of the problem makes the study more mathematically involved. Moreover, as illustrated by an example --- a two-level atom driven a continuous-mode two-photon state. Multi-photon filters can reveal interesting optical phenomena absent in either the single-photon filter case or the continuous-mode Fock state case.

Hongting Song; Guofeng Zhang; Zairong Xi

2014-09-29

167

ALMA DETECTION OF THE VIBRATIONALLY EXCITED HCN J = 4-3 EMISSION LINE IN THE AGN-HOSTING LUMINOUS INFRARED GALAXY IRAS 20551–4250  

SciTech Connect

We present results from our ALMA Cycle 0 observations, at the frequencies around the HCN, HCO{sup +}, and HNC J = 4-3 transition lines, of the luminous infrared galaxy IRAS 20551–4250 at z = 0.043, which is known to host an energetically important obscured active galactic nucleus (AGN). In addition to the targeted HCN, HCO{sup +}, and HNC J = 4-3 emission lines, two additional strong emission lines are seen, which we attribute to H{sub 2}S and CH{sub 3}CN(+CCH). The HCN-to-HCO{sup +} J = 4-3 flux ratio (?0.7) is higher than in the other starburst-dominated galaxy (?0.2) observed in our ALMA Cycle 0 program. We tentatively (?5?) detected the vibrationally excited (v {sub 2} = 1) HCN J = 4-3 (l = 1f) emission line, which is important for testing an infrared radiative pumping scenario for HCN. This is the second detection of this molecular transition in external galaxies. The most likely reason for this detection is not only the high flux of this emission line, but also the small molecular line widths observed in this galaxy, suggesting that vibrational excitation of HCN may be relatively common in AGN-hosting galaxies.

Imanishi, Masatoshi [Subaru Telescope, 650 North A'ohoku Place, Hilo, Hawaii, 96720 (United States); Nakanishi, Kouichiro, E-mail: masa.imanishi@nao.ac.jp [Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago de Chile (Chile)

2013-10-01

168

Frequency Multiplexed In Vivo Multiphoton Phosphorescence Lifetime Microscopy  

PubMed Central

Multiphoton microscopy (MPM) is widely used for optical sectioning deep in scattering tissue, in vivo [1–2]. Phosphorescence lifetime imaging microscopy (PLIM) [3] is a powerful technique for obtaining biologically relevant chemical information through Förster resonance energy transfer and phosphorescence quenching [4–5]. Point-measurement PLIM [6] of phosphorescence quenching probes has recently provided oxygen partial pressure measurements in small rodent brain vasculature identified by high-resolution MPM [7, 8]. However, the maximum fluorescence generation rate, which is inversely proportional to the phosphorescence lifetime, fundamentally limits PLIM pixel rates. Here we experimentally demonstrate a parallel-excitation/parallel collection MPM-PLIM system that increases pixel rate by a factor of 100 compared with conventional configurations while simultaneously acquiring lifetime and intensity images at depth in vivo. Full-frame three-dimensional in vivo PLIM imaging of phosphorescent quenching dye is presented for the first time and defines a new platform for biological and medical imaging. PMID:23472061

Howard, Scott S.; Straub, Adam; Horton, Nicholas; Kobat, Demirhan; Xu, Chris

2012-01-01

169

Frequency-multiplexed in vivo multiphoton phosphorescence lifetime microscopy  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy (MPM) is widely used in vivo for optical sectioning deep inside scattering tissue. Phosphorescence lifetime imaging microscopy (PLIM) is a powerful technique for obtaining biologically relevant chemical information through Förster resonance energy transfer and phosphorescence quenching. Point-measurement PLIM of phosphorescence quenching probes has recently provided oxygen partial pressure measurements in small rodent brain vasculature identified by high-resolution MPM. However, the maximum fluorescence generation rate, which is inversely proportional to the phosphorescence lifetime, fundamentally limits PLIM pixel rates. Here, we demonstrate experimentally a parallel-excitation/parallel-collection MPM-PLIM system that increases the pixel rate by a factor of 100 compared with conventional configurations, while simultaneously acquiring lifetime and intensity images at depth in vivo. Full-frame, three-dimensional, in vivo PLIM imaging of phosphorescent quenching dye is presented for the first time and defines a new platform for biological and medical imaging.

Howard, Scott S.; Straub, Adam; Horton, Nicholas G.; Kobat, Demirhan; Xu, Chris

2013-01-01

170

Polarization phenomena in multiphoton ionization of atoms  

NASA Technical Reports Server (NTRS)

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.

Jacobs, V. L.

1973-01-01

171

Polarization phenomena in multiphoton ionization of atoms.  

NASA Technical Reports Server (NTRS)

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 photo-electron 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.

Jacobs, V. L.

1973-01-01

172

Multiphoton microscopy in defining liver function  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

173

Multiphoton effects in coherent radiation spectra  

E-print Network

At measurements of gamma-radiation spectra from ultra-relativistic electrons in periodic structures, pileup of events in the calorimeter may cause significant deviation of the detector signal from the classically evaluated spectrum. That requires appropriate resummation of multiphoton contributions. We describe the resummation procedure for the photon spectral intensity and for the photon multiplicity spectrum, and apply it to the study of spectra of coherent radiation with an admixture of incoherent component. Impact of multiphoton effects on the shape of the radiation spectrum is investigated. The limit of high photon multiplicity for coherent radiation is explored. A method for reconstruction of the underlying single-photon spectrum from the multiphoton one is proposed.

Bondarenco, M V

2013-01-01

174

New developments in multimodal clinical multiphoton tomography  

NASA Astrophysics Data System (ADS)

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.

König, Karsten

2011-03-01

175

Near-infrared H2 emission from Herbig-Haro objects. I - A survey of low excitation objects  

NASA Astrophysics Data System (ADS)

A survey for H2 1-0 S(1) emission in 16 Herbig-Haro (HH) objects and three exciting stars for HH objects is reported. Eleven HH objects which show low-excitation optical spectra exhibit H2 emission. One object (HH 43) is more than twice as bright as any previously reported HH object. In addition, spectra in the range 1.6-2.55 microns are reported for HH 43 and HH 120, and a 2.0-2.55 micron spectrum is presented for HH 26. The spectra yield estimates of the H2 density and temperature ranges in these objects. The role of ultraviolet H2 emission-line fluorescence in HH 43 with respect to cascading among excited vibrational states of the ground electronic state is discussed. Models which may account for the combined ultraviolet, optical, and near-IR spectra of HHs are briefly analyzed.

Schwartz, Richard D.; Cohen, Martin; Williams, Peredur M.

1987-11-01

176

Near-infrared H2 emission from Herbig-Haro objects. I - A survey of low excitation objects  

NASA Technical Reports Server (NTRS)

A survey for H2 1-0 S(1) emission in 16 Herbig-Haro (HH) objects and three exciting stars for HH objects is reported. Eleven HH objects which show low-excitation optical spectra exhibit H2 emission. One object (HH 43) is more than twice as bright as any previously reported HH object. In addition, spectra in the range 1.6-2.55 microns are reported for HH 43 and HH 120, and a 2.0-2.55 micron spectrum is presented for HH 26. The spectra yield estimates of the H2 density and temperature ranges in these objects. The role of ultraviolet H2 emission-line fluorescence in HH 43 with respect to cascading among excited vibrational states of the ground electronic state is discussed. Models which may account for the combined ultraviolet, optical, and near-IR spectra of HHs are briefly analyzed.

Schwartz, Richard D.; Cohen, Martin; Williams, Peredur M.

1987-01-01

177

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

PubMed

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

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

2015-04-21

178

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

PubMed

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

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

179

Molecular photoelectron angular distribution rotations in multi-photon resonant ionization of H2 (+) by circularly polarized ultraviolet laser pulses.  

PubMed

We study effects of pulse durations on molecular photoelectron angular distributions (MPADs) in ultrafast circular polarization ultraviolet resonant ionization processes. Simulations performed on aligned H2 (+) by numerically solving time dependent Schrödinger equations show rotations of MPADs with respect to the molecular symmetry axes. It is found that in multi-photon resonant ionization processes, rotation angles are sensitive to pulse durations, which we attribute to the coherent resonant excitation between the ground state and the intermediate excited electronic state induced by Rabi oscillations. Multi-photon nonresonant and single photon ionization processes are simulated and compared which exhibit a constant rotation angle. An asymmetry parameter is introduced to describe the pulse duration sensitivity by perturbation theory models. Influence of pulse frequency detunings on MPADs is also investigated where oscillations of rotations are absent at long pulse durations due to nonresonance excitation. PMID:25877575

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

2015-04-14

180

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

181

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

182

Multiroute decomposition of complex molecules during IR multiphoton excitation  

Microsoft Academic Search

The rate constant of ethanol laser-induced decomposition (LIP) under the influence of pulsed laser IR radiation was calculated, and the relative yield of products by various routes was determined. Processes taking place during the interpulse interval were considered and the concentration of molecules was designated. When decomposition was small in comparison with the rate of relaxation processes, a quasisteady-state distribution

V. V. Alminderov; G. M. Milikh; S. Ya. Pshezhetskii; L. I. Trakhtenberg

1988-01-01

183

Label-free discrimination of normal and pulmonary cancer tissues using multiphoton fluorescence ratiometric microscopy  

NASA Astrophysics Data System (ADS)

We performed multiphoton excited autofluorescence and second harmonic generation microscopy for the distinction of normal, lung adenocarcinoma (LAC), and squamous cell carcinoma (SCC) specimens. In addition to morphological distinction, we derived quantitative metrics of cellular redox ratios for cancer discrimination. Specifically, the redox ratios of paired normal/SCC and normal/LAC specimens were found to be 0.53±0.05/0.41±0.06 and 0.56±0.02/0.35±0.06, respectively. The lower redox ratios in cancer specimens, indicating an increase in metabolic activity. These results show that the combination of morphological multiphoton imaging along with redox ratio indices can be used for the discrimination of normal and pulmonary cancer tissues.

Wang, Chun-Chin; Wu, Ruei-Jr; Lin, Sung-Jan; Chen, Yang-Fang; Dong, Chen-Yuan

2010-07-01

184

Nonlinear magic: multiphoton microscopy in the biosciences  

Microsoft Academic Search

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

Warren R Zipfel; Rebecca M Williams; Watt W Webb

2003-01-01

185

Polymer microcantilevers fabricated via multiphoton absorption polymerization  

E-print Network

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

Teich, Malvin C.

186

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

E-print Network

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

Draine, Bruce T.

187

Resonance enhanced multiphoton ionization spectroscopy of carbonyl sulphide  

NASA Astrophysics Data System (ADS)

Rydberg excited states of the OCS molecule in the energy range 70500-86000 cm-1 have been investigated via the two and three photon resonance enhancements they provide in the mass resolved multiphoton ionization (MPI) spectrum of a jet-cooled sample of the parent molecule. Spectral interpretation has been assisted by companion measurements of the kinetic energies of the photoelectrons that accompany the various MPI resonances. The present study supports the earlier conclusions of Weinkauf and Boesl [J. Chem. Phys. 98, 4459 (1993)] regarding five Rydberg origins in the 70500-73000 cm-1 energy range, attributable to, respectively, states of 3?, 1?, 3?, 1? and 1?+ symmetry arising from the 4p??3? orbital promotion. We also identify a further 21 Rydberg origins at higher energies. These partition into clumps with quantum defects ca. 3.5 and 4.5, which we associate with the orbital promotions np??3? (n=5,6), and others with near integer quantum defect which are interpretable in terms of excitation to s,d and (possibly) f Rydberg orbitals. We also identify MPI resonances attributable to CO(X 1?+) fragments and to S atoms in both their ground (3P) and excited (1D) electronic states. Analysis of the former resonances confirms that the CO(X) fragments resulting from one photon dissociation of OCS at excitation wavelengths ca. 230 nm are formed with a highly inverted, bimodal rotational state population distribution, whilst the latter are consistent with previous reports of the wavelength dependence for forming ground and excited state S atoms in the near uv photolysis of OCS.

Morgan, Ross A.; Orr-Ewing, Andrew J.; Ascenzi, Daniela; Ashfold, Michael N. R.; Buma, Wybren Jan; Scheper, Connie R.; de Lange, Cornelis A.

1996-08-01

188

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

PubMed

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

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

2015-02-11

189

Precision calculation of above-threshold multiphoton ionization in intense short-wavelength laser fields: The momentum-space approach and time-dependent generalized pseudospectral method  

E-print Network

with wavelengths from visible lights (4×102 nm) to infrared radiations (1×105 nm). With the recent development of intense and ultrashort-wavelength free-electron lasers [32–34], the study of multiphoton *zyzhou@ku.edu †sichu@ku.edu processes in the high...

Chu, Shih-I; Zhou, Zhongyuan

2011-01-19

190

Electronically excited molecules: Reaction kinetics and emission of light: Nanosecond infrared spectroscopy, electronic emission from chemical reactions  

NASA Astrophysics Data System (ADS)

A time-resolved IR absorption spectrometer capable of detecting chemical transients on the nanosecond timescale was designed, constructed, and successfully implemented. The spectrometer was used to characterize the vibrational relaxation of an open shell radical species, CF3, produced with excess energy from the photolysis of the parent CF3I compound. The effects of vibrational excitation in the CF3 radical on the reaction CF3 + Br2 yields CF3Br + Br were measured. Broadband data collection techniques were used to monitor the reactive and relaxation pathways simultaneously. The energetic radicals react no faster than the thermalized CF3 and may actually have a lower cross section for reaction. The spectrometer was also used to detect the gas phase absorption spectra of the polyatomic radicals. A thorough investigation into ozone-olefin reactions in a cryogenic matrix environment was completed. It was possible to complex ozone with various olefinic partners through careful control of the matrix deposition process, despite the very low (1-5 kcal/mole) activation energies for the ozonolysis reactions. The ground state complexes were observed to form a charge-transfer (CT) complex upon excitation.

Moore, C. B.

1992-02-01

191

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

192

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

SciTech Connect

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.

Chu, P.M.Y.

1991-10-01

193

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

194

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

PubMed

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. PMID:11541733

Cook, D J; Saykally, R J

1998-02-01

195

Simulated Infrared Emission Spectra of Highly Excited Polyatomic Molecules: A Detailed Model of the PAH-UIR Hypothesis  

NASA Astrophysics Data System (ADS)

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.

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

1998-01-01

196

Resonant multiphoton fragmentation spectrum of niobium dimer cation.  

PubMed

Resonant multiphoton fragmentation spectra of niobium dimer cation (Nb2(+)) have been obtained by utilizing laser vaporization of a Nb metal target. Ions are mass-selected with a time-of-flight mass spectrometer followed by a mass gate and then fragmented with a pulsed dye laser, and the resulting fragment ions are detected with a second time-of-flight reflectron mass spectrometer and multichannel plate. Photon resonances are detected by monitoring ion current as a function of fragmentation laser wavelength. A rich but complex spectrum of the cation is obtained. The bands display a characteristic multiplet structure that may be interpreted as due to transitions from the ground state X4Sigma(Omega g)- to several excited states, (B/D)4Pi(Omega u) and 4Sigma(Omega u)-. The ground state X4sigma(+/-1/2g)- is derived from the electron configuration pi(u)4 1sigma(g)2 2sigma(g)1 delta(g)2. The two spin-orbit components are split by 145 cm(-1) due to a strong second-order isoconfigurational spin-orbit interaction with the low-lying 2Sigma(+/-1/2g)+ state. The vibrational frequencies of the ground state and the excited-state of Nb2(+) are identified as well as molecular spin-orbit constants (A(SO)) in the excited state. The electronic structure of niobium dimer cation was investigated using density functional theory. For the electronic ground state, the predicted spectroscopic properties were in good agreement with experiment. Calculations on excited states reveal congested manifolds of quartet and doublet electronic states in the range 0-30,000 cm(-1), reflecting the multitude of possible electronic promotions among the 4d- and 5s-based molecular orbitals. Comparisons are drawn between Nb2(+) and the prevalent isoelectronic molecules V2(+)/NbV(+)/Nb2/V2/NbV2. PMID:19228052

Aydin, M; Lombardi, John R

2009-03-26

197

Multiphoton Imaging of Renal Regulatory Mechanisms  

NSDL National Science Digital Library

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.

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

2009-04-01

198

In vivo multiphoton imaging of collagen remodeling after microablative fractional rejuvenation  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

199

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

PubMed Central

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

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

2014-01-01

200

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

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

201

Multiphoton imaging of upconverting lanthanide nanoparticles in three dimensional models of cancer  

NASA Astrophysics Data System (ADS)

While upconverting lanthanide nanoparticles have numerous advantages over other exogenous contrast agents used in scanned multiphoton imaging, their long luminescence lifetimes cause images collected with non-descanned detection to be greatly blurred. We demonstrate herein the use of Richardson-Lucy deconvolution to deblur luminescence images obtained via multiphoton scanning microscopy. Images were taken of three dimensional models of colon and ovarian cancer following incubation with NaYF4:Yb,Er nanoparticles functionalized with an antibody for EGFR and folic acid respectively. Following deconvolution, images had a lateral resolution on par with the optimal performance of the imaging system used, ~1.2 ?m, and an axial resolution of ~5 ?m. Due to the relatively high multiphoton excitation efficiency of these nanoparticles, it is possible to follow binding of individual particles in tissue. In addition, their extreme photostability allows for prolonged imaging without significant loss in luminescence signal. With these advantageous properties in mind, we also discuss the potential application of upconverting lanthanide nanoparticles for tracking of specific, cancer relevant receptors in tissue.

Gainer, Christian F.; Romanowski, Marek

2013-02-01

202

Unified approach to multiphoton coherent states  

NASA Astrophysics Data System (ADS)

We obtain a large class of multiphoton annihilation operator (F) eigenstates by constructing an operator G° such that [F,G°]=1. We show that almost all known coherent states, including the squeezed states and other nonclassical states such as the cat and the kitten states follow from our approach. Further, we show that all of them can be expressed as an exponential operator acting on the vacuum of the operator F. The technique can be easily generalized to deformed bosons.

Shanta, P.; Chaturvedi, S.; Srinivasan, V.; Agarwal, G. S.; Mehta, C. L.

1994-03-01

203

Medium-induced multi-photon radiation  

E-print Network

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

Hao Ma; Carlos A. Salgado; Konrad Tywoniuk

2011-05-29

204

Video-rate resonant scanning multiphoton microscopy  

PubMed Central

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

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

2013-01-01

205

Multiphoton Biomedical Imaging and Photodynamic Therapy: Agents & Applications  

E-print Network

-reactive model Hydrophobic and hydrophilic dyes Two-Photon Photodynamic Therapy #12;"Two-photon laser scanning at the focus of the scanning pulsed-infrared laser beam, resulting in a much less harmful light dose during visible excitation. #12;Two-Photon Imaging can Afford 3D Localization Prepare cell Visualize and irradiate

Van Stryland, Eric

206

Multiphoton-double-ionization probability linearly depends on laser intensity: Experimental studies of barium  

NASA Astrophysics Data System (ADS)

Despite inherently complex multiphoton dynamics, our observations show that Ba double ionization with an infrared laser (8800-8920 cm-1) resembles a single-photon process; namely, its probability is proportional to the laser intensity. In this regime, single-electron ionization is due to a four-photon resonant transition through the highly perturbed state 6p21D2, whereas double ionization is realized by the two-electron mechanism. Furthermore, we argue that these conclusions are valid for other alkaline-earth-metal atoms and other parameters of laser radiation.

Bondar, I. I.; Suran, V. V.; Bondar, D. I.

2013-08-01

207

Collective Excitation of Rydberg-Atom Ensembles beyond the Superatom Model  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

208

Coherent multiphoton photoelectron emission from single au nanorods: the critical role of plasmonic electric near-field enhancement.  

PubMed

Electron emission from individual Au nanorods deposited on indium-tin-oxide (ITO) following excitation with femtosecond laser pulses near the rod longitudinal plasmon resonance is studied via scanning photoionization microscopy. The measured electron signal is observed to strongly depend on the excitation laser polarization and wavelength. Correlated secondary electron microscopy (SEM) and dark-field microscopy (DFM) studies of the same nanorods unambiguously confirm that maximum electron emission results from (i) laser polarization aligned with the rod long axis and (ii) laser wavelength resonant with the localized surface plasmon resonance. The experimental results are in good agreement with quantitative predictions for a coherent multiphoton photoelectric effect, which is identified as the predominant electron emission mechanism for metal nanoparticles under employed excitation conditions. According to this mechanism, the multiphoton photoemission rate is increased by over 10 orders of magnitude in the vicinity of a localized surface plasmon resonance, due to enhancement of the incident electromagnetic field in the particle near-field. These findings identify multiphoton photoemission as an extremely sensitive metric of local electric fields (i.e., "hot spots") in plasmonic nanoparticles/structures that can potentially be exploited for direct quantitation of local electric field enhancement factors. PMID:23194174

Grubisic, Andrej; Schweikhard, Volker; Baker, Thomas A; Nesbitt, David J

2013-01-22

209

Laser separation of oxygen isotopes by IR multiphoton dissociation of (CH 3 ) 2 O  

Microsoft Academic Search

Isotopically selective (with respect to 18O) one- and two-frequency multiphoton dissociation of dimethyl ether (CH3)2O by pulsed TEA CO2 laser radiation has been studied. The maximum primary selectivity, a?16, is attained with the dissociation yields of the desired component (CH3)218O ß18=5×10-4 and 1.7×10-2 for one- and two-frequency excitation, respectively. The dependences of MPD yields and selectivity on laser radiation frequency,

V. B. Laptev; E. A. Ryabov; L. M. Tumanova

1989-01-01

210

Identification of dirty necrosis in colorectal carcinoma based on multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

211

The multiphoton ionization spectrum of HBr. I. 74 000 to 85 000 cm-1  

NASA Astrophysics Data System (ADS)

The technique of resonantly enhanced multiphoton ionization with time-of-flight mass resolution has been used to measure the two-photon absorption spectrum of HBr. We have analyzed 37 bands and assigned them to transitions to the valence, ion-pair state and to Rydberg states belonging to the s?, p?, d?, p?, d?, and d? manifolds. Our results are in excellent agreement with the earlier work of Ginter, Ginter, and Tilford. In addition, we have analyzed twelve new electronic states as well as numerous bands of vibrationally excited levels of previously known electronic states. Strong mixing was observed among the 0+ states.

Callaghan, Robert; Gordon, Robert J.

1990-10-01

212

High-resolution fluorescence microscopy based on a cyclic sequential multiphoton process  

PubMed Central

We demonstrate high-resolution fluorescence microscopy based on a cyclic sequential multiphoton (CSM) process, which gives rise to fluorescence emission following a sequence of cyclic transitions between the bright and dark states of a fluorophore induced by pump and reverse light. By temporally modulating the reverse intensity, we can extract the fluorescence signal generated through the CSM process. We show that the demodulated fluorescence signal is nonlinearly proportional to the excitation intensities and it gives a higher spatial resolution than that of a confocal microscope. PMID:21258510

Isobe, Keisuke; Suda, Akira; Hashimoto, Hiroshi; Kannari, Fumihiko; Kawano, Hiroyuki; Mizuno, Hideaki; Miyawaki, Atsushi; Midorikawa, Katsumi

2010-01-01

213

Photon absorption in step-wise multi-photon activation fluorescence (SMPAF) of Sepia melanin  

NASA Astrophysics Data System (ADS)

Previous research has shown that melanin goes through a step-wise three-photon absorption process when the fluorescence is activated with high laser intensity. We have conducted further research using even higher laser intensity for the activation, and have shown the possibility of observing power dependence other than third-order. This article discusses the possible energy states of Sepia melanin by studying the power dependence curves of the step-wise multi-photon activated fluorescence signal. Three different excitation channels are activated. Possible reasons causing the three channels are discussed.

Lai, Zhenhua; Kerimo, Josef; DiMarzio, Charles

2013-02-01

214

Resonant multiphoton ionization spectra of molecules and molecular fragments. Technical report, October 1987--September 1988  

SciTech Connect

The objective of our research under this contract is to carry out studies of resonant enhanced multiphoton ionization (REMPI) processes in molecules. In the (n + 1) - REMPI process of interest an atom or molecule in a specific initial state absorbs n photons making a transition to an intermediate state from which it is subsequently ionized by absorption of an additional photon. A remarkable feature of resonant enhanced multiphoton ionization is that the narrow bandwidth radiation of lasers makes it possible (i) to select a specific rovibrational level in the initial state of a molecule or fragment, (ii) to resonantly pump this level up to a selected rotational-vibrational level of an excited electronic state, and (iii) to subsequently photoionize the state that has been resonantly excited. The extreme state-selectivity and sensitivity make REMPI both a tool with several practical applications and an important technique for probing the photoionization dynamics of vibrationally and electronically excited states. Some significant applications of this technique include its use for state-specific detection of species and diagnostics in combustion and chemical etching media and plasmas, (ii) for state-specific generation of molecular ions for use in ion-molecule reaction studies, and (iii) as a probe of photofragmentation and gas-surface scattering including alignment and orientation effects in these processes.

NONE

1997-07-01

215

Three- and Four-Photon Absorption of a Multiphoton Absorbing Fluorescent Probe  

NASA Astrophysics Data System (ADS)

High-order multiphoton excitation processes are becoming a reality for fluorescence imaging and phototherapy treatment because they afford minimization of scattered light losses and a reduction of unwanted linear absorption in the living organism transparency window, making them less susceptible to photodamage, while improving the irradiation penetration depth and spatial resolution. We report the four-photon-excited fluorescence emission of (7-benzothiazol-2-yl-9,-didecylfluoren-2-yl)-diphenylamine in hexane and its four-photon absorption cross section sigma4' = 8.1 × 10^-109 cm8 s3 photon^-3 for the transition S0 ---> S1 when excited at 1600 nm with a tunable optical parametric generator (OPG) pumped by picosecond laser pulses. When pumped at 1200 nm, three-photon absorption was observed, corresponding to the same transition.

Hernández, Florencio E.; Belfield, Kevin D.; Cohanoschi, Ion; Balu, Mihaela; Schafer, Katherine J.

2004-10-01

216

Multiphoton imaging with sub-30 fs Yb fiber laser  

NASA Astrophysics Data System (ADS)

An Yb fiber laser oscillator with sub-30 fs pulses compressed by MIIPS is tested for multiphoton microscopy. It leads to greatly improved third harmonic generation images. Multiphoton fluorescence, second and third harmonic generation modalities are compared on stained microspheres and unstained biological tissues.

Saytashev, Ilyas; Nie, Bai; Chong, Andy; Liu, Hui; Arkhipov, Sergey; Wise, Frank W.; Dantus, Marcos

2012-03-01

217

Multiphoton microscopy and fluorescence lifetime imaging provide a novel method in studying drug distribution and metabolism in the rat liver in vivo  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy has been shown to be a useful tool in studying drug distribution in biological tissues. In addition, fluorescence lifetime imaging provides information about the structure and dynamics of fluorophores based on their fluorescence lifetimes. Fluorescein, a commonly used fluorescent probe, is metabolized within liver cells to fluorescein mono-glucuronide, which is also fluorescent. Fluorescein and its glucuronide have similar excitation and emission spectra, but different fluorescence lifetimes. In this study, we employed multiphoton fluorescence lifetime imaging to study the distribution and metabolism of fluorescein and its metabolite in vivo in rat liver. Fluorescence lifetime values in vitro were used to interpret in vivo data. Our results show that the mean fluorescence lifetimes of fluorescein and its metabolite decrease over time after injection of fluorescein in three different regions of the liver. In conclusion, we have demonstrated a novel method to study a fluorescent compound and metabolite in vivo using multiphoton fluorescence lifetime imaging.

Thorling, Camilla A.; Dancik, Yuri; Hupple, Clinton W.; Medley, Gregory; Liu, Xin; Zvyagin, Andrei V.; Robertson, Tom A.; Burczynski, Frank J.; Roberts, Michael S.

2011-08-01

218

Optical temperature sensing of NaYbF4: Tm3+@SiO2 core-shell micro-particles induced by infrared excitation.  

PubMed

NaYbF(4):Tm3+@SiO(2) core-shell micro-particles were synthesized by a hydrothermal method and subsequent ultrasonic coating process. Optical temperature sensing has been observed in NaYbF4: Tm(3+)@SiO(2)core-shell micro-particles with a 980 nm infrared laser as excitation source.The fluorescence intensity ratios, optical temperature sensitivity, and temperature dependent population re-distribution ability from the thermally coupled (1)D(2)/(1)G(4) and (3)F(2) /(3)H(4) levels of the Tm(3+) ion have been analyzed as a function of temperature in the range of 100~700 K in order to check its availability as a optical temperature sensor. A better behavior as a lowtemperature sensor has been obtained with a minimum sensitivity of 5.4 × 10(-4) K(-1) at 430 K. It exhibits temperature induced population re-distribution from (1)D(2) /(1)G(4) thermally coupled levels at higher temperature range. PMID:24104034

Wang, Xiangfu; Zheng, Jin; Xuan, Yan; Yan, Xiaohong

2013-09-01

219

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

SciTech Connect

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

Clarkson, Jasper R.; Herbert, John M.; Zwier, Timothy S. [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Chemistry, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States)

2007-04-07

220

Characterization of powdered epidermal vaccine delivery with multiphoton microscopy  

NASA Astrophysics Data System (ADS)

Multiphoton laser scanning microscopy (MPLSM) has been adapted to non-invasively characterize hand-held powdered epidermal vaccine delivery technology. A near infrared femtosecond pulsed laser, wavelength at approximately 920 nm, was used to evoke autofluorescence of endogenous fluorophores within ex vivo porcine and human skin. Consequently, sub cellular resolution three-dimensional images of stratum corneum and viable epidermal cells were acquired and utilized to observe the morphological deformation of these cells as a result of micro-particle penetration. Furthermore, the distributional pattern of micro-particles within the specific skin target volume was quantified by measuring the penetration depth as revealed by serial optical sections in the axial plane obtained with MPLSM. Additionally, endogenous fluorescence contrast images acquired at the supra-basal layer reveal cellular structures that may pertain to dendritic Langerhans cells of the epidermis. These results show that MPLSM has advantages over conventional histological approaches, since three-dimensional functional images with sub-cellular spatial resolution to depths beyond the epidermis can be acquired non-invasively. Accordingly, we propose that MPLSM is ideal for investigations of powdered epidermal vaccine delivery.

Mulholland, William J.; Kendall, Mark A. F.; White, Nick; Bellhouse, Brian J.

2004-11-01

221

A study on a new 2? Rydberg state of SF by resonance-enhanced multiphoton ionization spectroscopy  

NASA Astrophysics Data System (ADS)

The (2 + 1) resonance-enhanced multiphoton ionization (REMPI) spectra of SF radicals have been recorded in the single-photon wavelength region of 271-286 nm for the first time. Four regular vibrational bands were observed and assigned as the transition by two-photon from the ground state to a 2? Rydberg state. The 2? Rydberg state arises from one-electron excitation from the 3? orbital of SF ground state to a 4p? Rydberg orbital, which converging to the first excited ionic state ( 1?). The term value Te, spin-orbit coupling constant A, vibrational frequency and rotational constants for the 2? Rydberg state are determined.

Wang, Tingting; Zheng, Xianfeng; Li, ChunYan; Chen, Yang

2006-07-01

222

In vivo non-invasive multiphoton tomography of human skin  

NASA Astrophysics Data System (ADS)

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.

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

2005-10-01

223

a UV+VUV Multiphoton Ionization Scheme for OH Radicals  

NASA Astrophysics Data System (ADS)

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).

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

2012-06-01

224

Excitation of the low lying vibrational levels of H2O by O(3P) as measured on Spacelab 2  

NASA Astrophysics Data System (ADS)

The data from the infrared telescope (IRT), which was flown on space shuttle Challenger Spacelab 2 mission (July 1985), were originally reported by Koch et al. (1987) as originating from near orbital emissions, primarily H2O. In this study, analysis of this data was extended to determine the collisional cross sections for the excitation of the low lying vibrational levels of H2O, present in the orbiter cloud, by atmospheric O(3P). The evaluation of the contribution to the measured signal from solar excitation and ram O excitation of outgassing H2O permits the determination of the H2O column density and the excitation cross section of the (101) level at an O(3P) velocity of approximately 7.75 km/s. Contributions to the radiation in the 1.7-3.0 micron band by transitions from the (100), (001), and multiquantum excited levels are discussed. The findings of the study are (1) the IRT data for the 4.5-9.5 micron and the nighttime data for the 1.7-3.0 micron sensors are consistent with being explained by collision excitation of H2O by O(3P), (2) diurnal variations of 4.5-9.5 micron intensities follow the model predicted O density for a full orbit, (3) daytime increases in the H2O cloud density were not evident, (4) the cross sections for the collisional excitation process are derived and compared to values computated by Johnson (1986) and Redmon et al. (1986), (5) theoretical investigation suggests greater than 60% of the radiation from H2O is a result of multiphoton emission resulting from collisional multiquanta excitation, and (6) the large daytime increase in the 1.7-3.0 micron intensity data suggests that O(+) may likely be instrumental in producing excited H2O(+) through charge exchange.

Meyerott, R. E.; Swenson, G. R.; Schweitzer, E. L.; Koch, D. G.

1994-09-01

225

Near infrared and visible luminescence from xerogels covalently grafted with lanthanide [Sm(3+), Yb(3+), Nd(3+), Er(3+), Pr(3+), Ho(3+)] ?-diketonate derivatives using visible light excitation.  

PubMed

A series of ternary lanthanide ?-diketonate derivatives covalently bonded to xerogels (named as Ln-DP-xerogel, Ln = Sm, Yb, Nd, Er, Pr, Ho) by doubly functionalized alkoxysilane (dbm-Si) was synthesized in situ via a sol-gel process. The properties of these xerogel materials were investigated by Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and fluorescence spectroscopy. The data and analyses suggest that the lanthanide derivatives have been covalently grafted to the corresponding xerogels successfully. Of importance here is that, after excitation with visible light (400-410 nm), the xerogels all show characteristic visible (Sm(3+)) as well as near-infrared (NIR; Sm(3+), Yb(3+), Nd(3+), Er(3+), Pr(3+), Ho(3+)) luminescence of the corresponding Ln(3+) ions, which is attributed to the energy transfer from the ligands to the Ln(3+) ions via an antenna effect. Exciting with visible light is advantageous over UV excitation. Furthermore, to the best of our knowledge, it is the first observation of NIR luminescence with visible light excitation from xerogels covalently bonded with the Sm(3+), Pr(3+), and Ho(3+) derivatives. Compared to lanthanide complexes (Ln = Er, Nd, Yb) functionalized periodic mesoporous organosilica (PMO) materials that exhibit similar optical properties reported in our previous work, the Ln-DP-xerogel (Ln = Sm, Yb, Nd, Er, Pr, Ho) in this case offer advantages in terms of ease of synthesis and handling and potentially low cost for emerging technological applications. Development of near-infrared luminescence of the lanthanide materials with visible light excitation is of strong interest to emerging applications such as chemosensors, laser systems, and optical amplifiers. PMID:24063535

Sun, Lining; Qiu, Yannan; Liu, Tao; Zhang, Jin Z; Dang, Song; Feng, Jing; Wang, Zhijuan; Zhang, Hongjie; Shi, Liyi

2013-10-01

226

Multiphoton photochemistry of red fluorescent proteins in solution and live cells.  

PubMed

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

Drobizhev, Mikhail; Stoltzfus, Caleb; Topol, Igor; Collins, Jack; Wicks, Geoffrey; Mikhaylov, Alexander; Barnett, Lauren; Hughes, Thomas E; Rebane, Aleksander

2014-08-01

227

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

NASA Astrophysics Data System (ADS)

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, taking the sample variability into account. We used this technique to measure sarcomere contracture in the presence of saxitoxin, and results were in agreement with mechanical measurements of atrial tissue contracture. Second, we characterized multiphoton microscopy of intact unlabeled arteries. We performed simultaneous detection of two-photon-excited fluorescence (2PEF) from elastin laminae and SHG from collagen fibers upon 860 nm excitation. Combined 2PEF/SHG images provide a highly specific, micron scale description of the architecture of these two major components of the vessel wall. We used this methodology to study the effects of lindane (a pesticide) on the artery wall structure and evidenced structural alteration of the vessel morphology.

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

2005-03-01

228

Multimodal optoacoustic and multiphoton fluorescence microscopy  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy is a powerful imaging modality that enables structural and functional imaging with cellular and sub-cellular resolution, deep within biological tissues. Yet, its main contrast mechanism relies on extrinsically administered fluorescent indicators. Here we developed a system for simultaneous multimodal optoacoustic and multiphoton fluorescence 3D imaging, which attains both absorption and fluorescence-based contrast by integrating an ultrasonic transducer into a two-photon laser scanning microscope. The system is readily shown to enable acquisition of multimodal microscopic images of fluorescently labeled targets and cell cultures as well as intrinsic absorption-based images of pigmented biological tissue. During initial experiments, it was further observed that that detected optoacoustically-induced response contains low frequency signal variations, presumably due to cavitation-mediated signal generation by the high repetition rate (80MHz) near IR femtosecond laser. The multimodal system may provide complementary structural and functional information to the fluorescently labeled tissue, by superimposing optoacoustic images of intrinsic tissue chromophores, such as melanin deposits, pigmentation, and hemoglobin or other extrinsic particle or dye-based markers highly absorptive in the NIR spectrum.

Sela, Gali; Razansky, Daniel; Shoham, Shy

2013-03-01

229

Multiphoton ionization of large water clusters  

SciTech Connect

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.

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

230

Imaging the morphological change of tissue structure during the early phase of esophageal tumor progression using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

Esophageal cancer is a common malignancy with a very poor prognosis. Successful strategies for primary prevention and early detection are critically needed to control this disease. Multiphoton microscopy (MPM) is becoming a novel optical tool of choice for imaging tissue architecture and cellular morphology by two-photon excited fluorescence. In this study, we used MPM to image microstructure of human normal esophagus, carcinoma in situ (CIS), and early invasive carcinoma in order to establish the morphological features to differentiate these tissues. The diagnostic features such as the appearance of cancerous cells, the significant loss of stroma, the absence of the basement membrane were extracted to distinguish between normal and cancerous esophagus tissue. These results correlated well with the paired histological findings. With the advancement of clinically miniaturized MPM and the multi-photon probe, combining MPM with standard endoscopy will therefore allow us to make a real-time in vivo diagnosis of early esophageal cancer at the cellular level.

Xu, Jian; Kang, Deyong; Xu, Meifang; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

2012-12-01

231

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

PubMed

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

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

2014-02-14

232

High Resolution Multiphoton Spectroscopy by a Tunable Free-Electron-Laser Light  

NASA Astrophysics Data System (ADS)

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 Se 1 and (0 ,1 )0 De 1 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.

Žitnik, M.; Miheli?, A.; Bu?ar, K.; Kav?i?, M.; Rubensson, J.-E.; Svanquist, M.; Söderström, J.; Feifel, R.; Sâthe, 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

233

Generation of extended light-sheets for single and multi-photon fluorescence microscopy  

NASA Astrophysics Data System (ADS)

We theoretically propose and computationally demonstrate the generation of extended light-sheet for fluorescence microscopy. This is made possible by the introduction of a specially designed double-window spatial filter that allows the light to pass through the periphery and center of a cylindrical lens. When illuminated with a plane wave, the proposed filter results in an extended depth-of-focus along with side-lobes which are due to other interferences in the transverse focal plane. Computational studies show a maximum extension of light-sheet by 3.38 times for single photon excitation and 3.68 times for multiphoton excitation as compared to state-of-art single plane illumination microscopy system. This technique may facilitate the study of large biological specimens (such as Zebrafish embryo and tissue) with high spatial resolution and reduced photobleaching.

Purnapatra, Subhajit B.; Pratim Mondal, Partha

2013-07-01

234

An adaptive approach for uniform scanning in multifocal multiphoton microscopy with a spatial light modulator.  

PubMed

We propose high-quality generation of uniform multiple fluorescence spots (MFS) with a spatial light modulator (SLM) and demonstrate uniform laser scanning in multifocal multiphoton microscopy (MMM). The MFS excitation method iteratively updates a computer-generated hologram (CGH) using correction coefficients to improve the fluorescence intensity distribution in a dye solution whose consistency is uniform. This simple correction method can be applied for calibration of the MMM before observation of living tissue. We experimentally demonstrate an improvement of the uniformity of a 10 × 10 grid of MFS by using a dye solution. After the calibration, we performed laser scanning with two-photon excitation to observe fluorescent polystyrene beads, as well as the gastric gland of a guinea pig specimen. PMID:24515023

Matsumoto, Naoya; Okazaki, Shigetoshi; Fukushi, Yasuko; Takamoto, Hisayoshi; Inoue, Takashi; Terakawa, Susumu

2014-01-13

235

Revealing femtosecond multiphoton induced multichannel molecular ionization and fragmentation dynamics by photoelectron-photoion coincidence imaging  

NASA Astrophysics Data System (ADS)

We report on photoelectron-photoion coincidence imaging after single-color (400 nm) multiphoton excitation of CFI at laser intensities of about 1012Watt/cm. The dominant ionic species are the parent CFI and the CF3+ fragment from four-photon excitation. Photoelectrons are ejected leaving the parent ion at an internal energy above the dissociation limit leading to fragmentation in CF3++I with low kinetic energy. Weaker dissociation channels of fast CF3++I fragments or fast I+CF fragments result from the absorption of a fifth photon by the ionized CFI parent. We propose a new assignment of 7s, 8s intermediate Rydberg levels in CFI resonant at the three-photon level.

Vredenborg, Arno; Roeterdink, Wim G.; de Lange, Cornelis A.; Janssen, Maurice H. M.

2009-08-01

236

Time resolved UV-spectroscopy of NH3 molecules vibrationally excited by CO2 laser radiation  

Microsoft Academic Search

The excitation of ammonia by a pulsed CO2 laser is investigated with emphasis on processes associated with collisions with argon. The previously reported multiphoton dissociation of NH3 under collisionless conditions; and the excitation mechanisms of nonresonant low vibrational levels were clarified to allow an appropriate selection of laser lines. A repertory was made of all vibrational rotational levels up to

H. Holbach

1980-01-01

237

Dynamic Multiphoton Imaging: A Live View from Cells to Systems  

NSDL National Science Digital Library

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

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

2005-02-01

238

Differentiation of normal and cancerous lung tissues by multiphoton imaging  

E-print Network

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

Wang, Chun-Chin

239

Extending imaging depth of multiphoton microscopy  

E-print Network

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 ...

Cha, Jae Won

2007-01-01

240

Maximizing fluorescence collection efficiency in multiphoton microscopy  

PubMed Central

Understanding fluorescence propagation through a multiphoton microscope is of critical importance in designing high performance systems capable of deep tissue imaging. Optical models of a scattering tissue sample and the Olympus 20X 0.95NA microscope objective were used to simulate fluorescence propagation as a function of imaging depth for physiologically relevant scattering parameters. The spatio-angular distribution of fluorescence at the objective back aperture derived from these simulations was used to design a simple, maximally efficient post-objective fluorescence collection system. Monte Carlo simulations corroborated by data from experimental tissue phantoms demonstrate collection efficiency improvements of 50% – 90% over conventional, non-optimized fluorescence collection geometries at large imaging depths. Imaging performance was verified by imaging layer V neurons in mouse cortex to a depth of 850 ?m. PMID:21934897

Zinter, Joseph P.; Levene, Michael J.

2011-01-01

241

Intravital multiphoton microscopy for imaging hepatobiliary function  

NASA Astrophysics Data System (ADS)

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

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

2007-07-01

242

Multiphoton microscopy of cleared mouse organs  

NASA Astrophysics Data System (ADS)

Typical imaging depths with multiphoton microscopy (MPM) are limited to less than 300 ?m in many tissues due to light scattering. Optical clearing significantly reduces light scattering by replacing water in the organ tissue with a fluid having a similar index of refraction to that of proteins. We demonstrate MPM of intact, fixed, cleared mouse organs with penetration depths and fields of view in excess of 2 mm. MPM enables the creation of large 3-D data sets with flexibility in pixel format and ready access to intrinsic fluorescence and second-harmonic generation. We present high-resolution images and 3-D image stacks of the brain, small intestine, large intestine, kidney, lung, and testicle with image sizes as large as 4096×4096 pixels.

Parra, Sonia G.; Chia, Thomas H.; Zinter, Joseph P.; Levene, Michael J.

2010-05-01

243

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

SciTech Connect

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.

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

244

Cross sections for ionization and excitation in the two-photon transitions of CO BX(0,0)  

Microsoft Academic Search

High-resolution spectroscopy of CO B-X is being performed to measure cross sections for the processes of two-photon absorption and ionization that underlie two methods often used for sensitive detection of CO in flames, namely, two-photon LIF and 2+1 resonance-enhanced multiphoton ionization (REMPI) via B(v=0). The use of multiphoton excitation is, for even LIF diagnostics, a practical necessity since the allowed

M. D. Di Rosa; R. L. Farrow

1997-01-01

245

Particle modeling of microplasma generated by resonance enhanced multiphoton ionization  

NASA Astrophysics Data System (ADS)

Resonance-enhanced multiphoton ionization (REMPI) is a technique applied to the spectroscopy of atoms. The REMPI technique typically involves a resonant single or multiple photon absorption to an electronically excited intermediate state followed by another photon which ionizes the atom. Rayleigh scattering of REMPI plasma has given rise to a non-intrusive, time accurate measurement of electron formation and loss, which lead to many applications viz. trace species detection and micro-plasma diagnostics. It is very important to quantify the expansion process and the evolution of energy of electrons and ions. The operation scale of this process is in microns and non continuum nature of the process lead to the use of PIC/MCC scheme to compu- tationally model REMPI technique. This work attempts to understand and analyze the processes taking place during the expansion of REMPI plasma computationally using the PIC/MCC scheme. One dimensional and two dimensional approximations are considered to analyze the REMPI plasma expansion in Argon gas generated by a laser with a focal shape of a prolate ellipsoid. The expansion of the plasma is found to be very sensitive to the initial velocity distribution of the electrons. REMPI plasma expansion is shown to be ambipolar in nature, with the radial expansion more predominant than axial expansion, hence requiring the 2D model. Electron energy distribution functions(EEDFs) are found at various radial locations along with the corresponding mean energies. The deviation of the EEDFs from that of equilibrium Maxwell-Boltzmann energy distribution is presented both qualitatively and quanti- tatively, indicating the predominant processes at various instances in time.

Tholeti, Siva Sashank

246

Stepwise multiphoton activation fluorescence reveals a new method of melanin detection  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

247

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

PubMed Central

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

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

2008-01-01

248

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

PubMed Central

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

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

249

Time- and spectral-resolved multiphoton imaging of fresh bladder biopsies  

NASA Astrophysics Data System (ADS)

Human tissues intrinsically contains many fluorophores, as such NADH, elastin, collagen, and flavins, that can be excited and imaged using multiphoton microscopy, up to 150 microns depth. In this work we used combined two photon intrinsic fluorescence (TPE), second harmonic generation microscopy (SHG), fluorescence lifetime imaging microscopy (FLIM), and multispectral two photon emission detection (MTPE) to investigate different kinds of human ex-vivo fresh biopsies of bladder. Morphological and spectroscopic analyses allowed to characterize both healthy and pathological tissue samples in a good agreement with common routine histology. In particular, we examined tissue samples from bladder normal mucosa, and bladder carcinoma in-situ (CIS), finding both morphological and spectroscopic differences. From the morphological point of view, cancer cells appeared more elongated with respect to corresponding normal cells; they also exhibited a different nucleus to cytoplasm ratio. From the spectroscopic point of view, we found differences between the two tissue types in both spectral emission and fluorescence lifetime distribution. Even if further analysis, as well as a more significant statistics on a large number of samples would be helpful to discriminate between low and high grade cancer, our method is a promising tool to be used as diagnostic confirmation of histological results, as well as a diagnostic tool in a multiphoton endoscope or cystoscope to be used in in-vivo imaging applications.

Cicchi, Riccardo; Crisci, Alfonso; Nesi, Gabriella; Cosci, Alessandro; Giancane, Saverio; Carini, Marco; Pavone, Francesco S.

2009-07-01

250

Multiphoton microscopic imaging of fibrotic focus in invasive ductal carcinoma of the breast  

NASA Astrophysics Data System (ADS)

During the proliferation of breast cancer, the desmoplastic can evoke a fibrosis response by invading healthy tissue. Fibrotic focus (FF) in invasive ductal carcinoma (IDC) of the breast had been reported to be associated with significantly poorer survival rate than IDC without FF. As an important prognosis indicator, it's difficult to obtain the exact fibrotic information from traditional detection method such as mammography. Multiphoton imaging based on two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) has been recently employed for microscopic examination of unstained tissue. In this study, multiphoton microscopy (MPM) was used to image the fibrotic focus in invasive ductal carcinoma tissue. The morphology and distribution of collagen in fibrotic focus can be demonstrated by the SHG signal. Variation of collagen between IDC with and without FF will be examined and further characterized, which may be greatly related to the metastasis of breast cancer. Our result suggested that the MPM can be efficient in identifying and locating the fibrotic focus in IDC. Combining with the pathology analysis and other detecting methods, MPM owns potential in becoming an advanced histological tool for detecting the fibrotic focus in IDC and collecting prognosis information, which may guide the subsequent surgery option and therapy procedure for patients.

Chen, Sijia; Nie, Yuting; Lian, Yuane; Wu, Yan; Fu, Fangmeng; Wang, Chuan; Zhuo, Shuangmu; Chen, Jianxin

2014-11-01

251

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Results and prospects of laser separation of oxygen isotopes by IR multiphoton dissociation of molecules  

Microsoft Academic Search

An experimental search was made for an initial oxygen compound suitable for laser separation of oxygen isotopes by IR multiphoton dissociation of molecules. Over ten molecules with C---O, Si---O, Cr=O, and C=O bonds were investigated. The excitation was provided by pulsed TEA CO2 laser radiation, and also by its second harmonic. Measurements were made of the dissociation yields of the

Vladimir B. Laptev; Evgenii A. Ryabov; L. M. Tumanova

1995-01-01

252

Multiphoton spectral analysis of benzo[a]pyrene uptake and metabolism in breast epithelial cell lines  

PubMed Central

Quantification of polycyclic aromatic hydrocarbons (PAH) and their metabolites within living cells and tissues in real time using fluorescence methods is complicated due to overlaping excitation and/or emission spectra of metabolites. In this study, simultaneous analysis of several metabolites of a prototype carcinogenic PAH, benzo[a]pyrene (BaP) in undifferentiated (MCF10A) and differentiated (MCF10CA1h) breast cancer cells was performed using single-cell multiphoton spectral analysis. The two cell types were selected for this study because they are known to have differences in BaP uptake and metabolism and induction of aryl hydrocarbon receptor-dependent ethoxyresorufin-O-deethylase (EROD) activity. Multiphoton microscopy spectral analysis performed in cells exposed to BaP for 24 hr identified 5 major peaks of fluorescence that were monitored within spectral bands. A comparison of the fluorescence peaks within these bands to those of BaP metabolite standards indicated that a peak in the spectral range of 393–415 nm matched benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide(±),(anti) (BPDE), the ultimate carcinogenic BaP metabolite. In addition, the 426–447 nm band matched the major metabolites 3-hydroxybenzo[a]pyrene (3-OH BaP) and 9-hydroxybenzo[a]pyrene (9-OH BaP); the 458–479 nm band corresponded to the secondary metabolite benzo[a]pyrene-3,6-dione (3,6 BPQ); and a peak at 490–530 nm matched the parent compound, BaP. Multiphoton spectral analysis also revealed differences in fluorescence intensities between MCF10A and MCF10CA1h cells within three spectral bands: 393–415 nm, 426–447 nm and 458–479 nm which were partially reversed with cyclosporine A suggesting differences in efflux mechanisms between cell lines. These results demonstrate the feasibility of analyzing BaP metabolism in situ by multiphoton spectral analysis and also identifying cell-type differences in BaP accumulation and metabolism. PMID:19182432

Barhoumi, Rola; Catania, Jeffrey M.; Parrish, Alan R.; Awooda, Igbal; Tiffany-Castiglioni, Evelyn; Safe, Stephen; Burghardt, Robert C.

2009-01-01

253

Resonance enhanced multiphoton ionisation probing of H atoms in a hot lament chemical vapour deposition reactor  

E-print Network

Resonance enhanced multiphoton ionisation probing of H atoms in a hot Ðlament chemical vapour multiphoton ionisation (MPI) spectroscopy, resonance enhanced at the two photon energy by the state, to detect

Bristol, University of

254

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

255

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

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.

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

256

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual progress report, March 1992--February 1993  

SciTech Connect

In this report, the author will review the progress made in his studies of ion rotational distributions resulting from resonance enhanced multiphoton ionization of excited electronic states and from single-photon ionization of ground electronic states of jet-cooled molecules by coherent VUV and XUV radiation. To do so he will select a few examples from his studies which serve to highlight his progress and to identify the background and significance of the specific spectral features and systems he has chosen to study.

NONE

1993-12-31

257

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

SciTech Connect

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.

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

258

When can temporally focused excitation be axially shifted by dispersion?  

PubMed

Temporal focusing (TF) allows for axially confined wide-field multi-photon excitation at the temporal focal plane. For temporally focused Gaussian beams, it was shown both theoretically and experimentally that the temporal focus plane can be shifted by applying a quadratic spectral phase to the incident beam. However, the case for more complex wave-fronts is quite different. Here we study the temporal focus plane shift (TFS) for a broader class of excitation profiles, with particular emphasis on the case of temporally focused computer generated holography (CGH) which allows for generation of arbitrary, yet speckled, 2D patterns. We present an analytical, numerical and experimental study of this phenomenon. The TFS is found to depend mainly on the autocorrelation of the CGH pattern in the direction of the beam dispersion after the grating in the TF setup. This provides a pathway for 3D control of multi-photon excitation patterns. PMID:24664057

Leshem, B; Hernandez, O; Papagiakoumou, E; Emiliani, V; Oron, D

2014-03-24

259

Permutation asymmetry inducing entanglement between degrees of freedom in multiphoton states  

E-print Network

We describe and examine entanglement between different degrees of freedom in multiphoton states based on the permutation properties. From the state description, the entanglement comes from the permutation asymmetry. According to the different permutation properties, the multiphoton states can be divided into several parts. It will help to deal with the multiphoton interference, which can be used as the measurement of the entanglement.

F. W. Sun; B. H. Liu; C. W. Wong; G. C. Guo

2008-07-31

260

Soliton dynamics in the multiphoton plasma regime  

PubMed Central

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.

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

2013-01-01

261

Resonantly Enhanced Multiphoton Ionization Circular Dichroism (REMPICD)  

NASA Astrophysics Data System (ADS)

Linear and non-linear circular dichroism of R-(+)-3-methylcyclopentanone is reported in the gas and liquid phase. Measurements of (2+1) resonance-enhanced multiphoton ionization circular dichroism (REMPICD) for nozzle-jet expanded molecular beams of the equatorial conformer of R-3MCP are presented. Monitoring either mass-selected cations or photo-electrons produced via (2+1) REMPI through the n -> 3s Rydberg transition yielded a REMPICD of +1.5± 0.5% [ REMPICD ? 2(IL -- IR)/( IL + IR), where IL/R refers to the ion/electron signal for left-/right-circularly polarized light. A racemic mixture of 3-methylcyclopentanone showed no significant CD. The REMPICD is larger and of opposite sign than the 1-photon CD at the n -> 3s transition. It appears that the REMPICD is dominated by the continuum transition. Measurements of 1-photon CD as a function of temperature provides information on the enthalpy difference between the equatorial and axial conformers of 3MCP. Density Function Theory calculations also support these measurements.

Al-Basheer, Watheq; Li, Runhua; Sullivan, Rodney; Pagni, Richard; Compton, Robert

2006-11-01

262

Hypericin-Mediated Destruction of Collagen Fibers Revealed by Multiphoton Microscopy  

NASA Astrophysics Data System (ADS)

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

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

263

Evaluation of multiphoton effects in down-conversion  

SciTech Connect

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.

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

264

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

SciTech Connect

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.

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

265

Nonlinear optical imaging characteristics of colonic adenocarcinoma using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

266

Adaptive optics multiphoton microscopy to study ex vivo ocular tissues  

NASA Astrophysics Data System (ADS)

We develop an adaptive optics (AO) multiphoton microscope by incorporating a deformable mirror and a Hartmann-Shack wavefront sensor. The AO module operating in closed-loop is used to correct for the aberrations of the illumination laser beam. This increases the efficiency of the nonlinear processes in reducing tissue photodamage, improves contrast, and enhances lateral resolution in images of nonstained ocular tissues. In particular, the use of AO in the multiphoton microscope provides a better visualization of ocular structures, which are relevant in ophthalmology. This instrument might be useful to explore the possible connections between changes in ocular structures and the associated pathologies.

Bueno, Juan M.; Gualda, Emilio J.; Artal, Pablo

2010-11-01

267

Remote focusing for programmable multi-layer differential multiphoton microscopy  

PubMed Central

We present the application of remote focusing to multiphoton laser scanning microscopy and utilize this technology to demonstrate simultaneous, programmable multi-layer imaging. Remote focusing is used to independently control the axial location of multiple focal planes that can be simultaneously imaged with single element detection. This facilitates volumetric multiphoton imaging in scattering specimens and can be practically scaled to a large number of focal planes. Further, it is demonstrated that the remote focusing control can be synchronized with the lateral scan directions, enabling imaging in orthogonal scan planes. PMID:21326641

Hoover, Erich E.; Young, Michael D.; Chandler, Eric V.; Luo, Anding; Field, Jeffrey J.; Sheetz, Kraig E.; Sylvester, Anne W.; Squier, Jeff A.

2010-01-01

268

Optical clearing and multiphoton imaging of paraffin-embedded specimens  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

269

MULTIPHOTON DISSOCIATION OF POLY ATOMIC MOLECULES  

E-print Network

intensity and energy fluence, because the dissociation lifetimeintensities CF,I is not excited much beyond its dissociation energy, because the dissociation lifetimeintensity for pulse dura­ tions longer than 0.6 ns. We call this regime lifetime

Schulz, Peter A.

2010-01-01

270

Excitation with Effective Subcycle Laser Pulses  

NASA Astrophysics Data System (ADS)

We have used laser pulses with a temporally shaped polarization to demonstrate the multiphoton excitation of the xenon 5g state within a subcycle of a laser pulse. Our polarization gated laser pulses are composed of circularly polarized sections at the leading and trailing edges of the pulse and of an experimentally defined linearly polarized central part. Only the linear part (the gate) of the pulse can excite neutral xenon in the 5g state. The transition cannot be driven with circularly polarized light because the number of photons needed would cause a violation of selection rules for the change of the magnetic quantum number. We show that the linearly polarized central part can be reduced to a subcycle pulse. This allows us to study excitation with an effective pulse as short as 2.3 fs at 800 nm. Electron imaging spectroscopy has been used to visualize the presence of excited states as a function of the pulse duration of the gate.

Marceau, C.; Gingras, G.; Witzel, B.

2013-11-01

271

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual technical report  

SciTech Connect

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 state before it can decay. A remarkable feature of REMPI, and one that is very basic to many of its applications and uses, is that the very narrow bandwidth of the {open_quotes}pump{close_quotes} laser makes it possible to select a specific vibrational and rotational level in the initial state and to prepare the excited state of interest in a single vibrational and rotational level. Thus, by suitable choice of the photon pump transition, it is possible to selectively ionize a species of interest without ionizing any other species that might be present. This feature makes REMPI one of the most powerful tools for ultrasensitive detection of species. With REMPI it is also possible to study the photoionization dynamics of a single rotational level of an excited electronic state. Such state-resolved studies can certainly be expected to provide significant insight into the underlying dynamics of molecular photoionization.

NONE

1997-07-01

272

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)

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.

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

2012-02-01

273

The Influence of Multi-Photon Absorption on Photon Statistics  

Microsoft Academic Search

A previous approximation scheme [6] which allowed to calculate, in a simple manner, the quantity n2\\/ ( mean value and n2 variance of the photon number) in the course of a multi-photon absorption process, is extended to study the change of the shape of the photon distribution, too. It turns out that there is a tendency to symmetrize the distribution.

Ulrike Mohr; Harry Paul

1978-01-01

274

Enhancing multiphoton rates with quantum memories J. Nunn,1,  

E-print Network

. Walmsley1 1 Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom 2 Centre for Quantum Technologies, National University of Singapore, 117543, Singapore (Dated: August 9 required to run experiments of this kind, the quality of the multiphoton states produced is limited

Sheldon, Nathan D.

275

Generalized parity in multi-photon Rabi model  

E-print Network

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

Bart?omiej Gardas; Jerzy Dajka

2013-01-16

276

Germinal Center Dynamics Revealed by Multiphoton Microscopy with a  

E-print Network

Germinal Center Dynamics Revealed by Multiphoton Microscopy with a Photoactivatable Fluorescent to this work *Correspondence: nussen@rockefeller.edu DOI 10.1016/j.cell.2010.10.032 SUMMARY The germinal center Germinal centers (GCs) were first described in the 19th century as distinct microanatomical regions

277

Intravital Imaging of the Kidney Using Multiparameter Multiphoton Microscopy  

Microsoft Academic Search

Intravital optical microscopy provides a powerful means of studying the cell biology in the most physiologically relevant setting. The ability of multiphoton microscopy to collect optical sections deep into biological tissues has opened up the field of intravital microscopy to high-resolution studies of multiple organs. Presented here are examples of how two-photon microscopy can be applied to intravital studies of

Kenneth W. Dunn; Ruben M. Sandoval; Bruce A. Molitoris

2003-01-01

278

Rotational multiphoton endoscopy with a 1 m fiber laser system  

E-print Network

Rotational multiphoton endoscopy with a 1 m fiber laser system Gangjun Liu,1 Tuqiang Xie,1 Ivan V-based femtosecond laser. The rotational probe is based on a double-clad photonic crystal fiber, a gradient index a diameter of 2.2 mm and can provide 360° full-view rotation. The fiber laser provides ultrashort pulses

Chen, Zhongping

279

Endogenous Optical Biomarkers of Ovarian Cancer Evaluated with Multiphoton Microscopy  

Microsoft Academic Search

Purpose: Among gynecologic cancers, ovarian cancer is the second most common and has the highest mortality. Currently, there is no accurate early diagnostic tech- nique for ovarian cancer. Furthermore, little is under- stood regarding the early progression of this disease. We have imaged multiphoton interactions of endoge- nous tissue constituents from normal and abnormal ovarian biopsies that were kept viable

Nathaniel D. Kirkpatrick; Molly A. Brewer; Urs Utzinger

280

Anomalous Multiphoton Photoelectric Effect in Ultrashort Time Scales  

Microsoft Academic Search

In a multiphoton photoelectric process, an electron needs to absorb a given number of photons to escape the surface of a metal. It is shown for the first time that this number is not a constant depending only on the characteristics of the metal and light, but varies with the interaction duration in ultrashort time scales. The phenomenon occurs when

J. Kupersztych; M. Raynaud

2005-01-01

281

The two-photon excitation of SiO2-coated Y2O3:Eu3+ nanoparticles by a near-infrared femtosecond laser  

Microsoft Academic Search

In order to improve the photoluminescence property of Eu3+-doped nanoparticles, Y2O3:Eu3+ nanoparticles were synthesized using the Pechini-type sol–gel method, then coated with SiO2 shells by using the Stöber method for different coating times. The SiO2-coated nanoparticles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, and their photoluminescence spectra were recorded

Qiang Lü; AiHua Li; FengYun Guo; Liang Sun; LianCheng Zhao

2008-01-01

282

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

NASA Astrophysics Data System (ADS)

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.

Chia, Thomas H.

283

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

SciTech Connect

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

Marcos Dantus

2008-09-23

284

A study of the infrared emission from the O I (3d 3D0) and (4s 5S0) states produced by electron impact excitation of O2  

NASA Technical Reports Server (NTRS)

The absolute emission cross section values for the O I(3p 3P-3d 3D0, lambda = 11,287 A) and the (3p 5P-4s 5S0, lambda = 11,299 A) multiplets excited by electron impact on O2 have been measured. These infrared oxygen emission features appear prominently in auroral spectra and were observed in electron bombardment of O2. The former cross section has a value of 3.05 x 10 to the -19th + or - 15 percent at 100 eV, while the latter's value is 4.14 x 10 to the -19th sq cm + or - 15 percent. The quintet emission at lambda = 11,299 A is the only deexcitation channel for the 4s 5S0 state and thus represents the total excitation cross section for that state. However, the lambda = 11,287 A branch from the O I (3d 3D0) state only constitutes about 25 percent of the total 3d 3D0 cross section, with the major branch from this state being the transition to the ground state observed at lambda = 1027 A. The branching ratio is in good agreement with the theoretical calculation of Padhan and Saraph (1977).

Erdman, P. W.; Zipf, E. C.

1987-01-01

285

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

NASA Technical Reports Server (NTRS)

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

Hora, Joseph L.; Latter, William B.

1994-01-01

286

Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube  

PubMed Central

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

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

2015-01-01

287

Evaluation of endogenous species involved in brain tumors using multiphoton photoacoustic spectroscopy  

NASA Astrophysics Data System (ADS)

It has been shown that using non-resonant multiphoton photoacoustic spectroscopy (NMPPAS), excised brain tumor (grade III astrocytoma) and healthy tissue can be differentiated from each other, even in neighboring biopsy samples[1, 2]. Because of this, this powerful technique offers a great deal of potential for use as a surgical guidance technique for tumor margining with up to cellular level spatial resolution[3]. NMPPAS spectra are obtained by monitoring the non-radiative relaxation pathways via ultrasonic detection, following two-photon excitation with light in the optical diagnostic window (740nm-1100nm). Based upon significant differences in the ratiometric absorption of the tissues following 970nm and 1100nm excitation, a clear classification of the tissue can be made. These differences are the result of variations in composition and oxidation state of certain endogenous biochemical species between healthy and malignant tissues. In this work, NADH, NAD+ and ATP were measured using NMPPAS in model gelatin tissue phantoms to begin to understand which species might be responsible for the observed spectral differences in the tissue. Each species was placed in specific pH environments to provide control over the ratio of oxidized to reduced forms of the species. Ratiometric analyses were then conducted to account for variability caused due to instrumental parameters. This paper will discuss the potential roles of each of the species for tumor determination and their contribution to the spectral signature.

Dahal, Sudhir; Cullum, Brian M.

2013-05-01

288

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

289

Matrix isolation study of the interaction of excited neon atoms with NF3. Infrared spectra of NF + 3, NF + 2, and NF - 2  

NASA Astrophysics Data System (ADS)

When a Ne:NF3 sample is codeposited at approximately 5 K with a beam of pure neon that has been passed through a microwave discharge, the infrared spectrum of the resulting deposit includes prominent absorptions of NF2 and a structured absorption assigned to NF. In addition, two groups of absorptions contributed by previously unassigned products can be distinguished, based on their behavior on subsequent filtered mercury-arc irradiation of the deposit. Three absorptions which disappear readily on near-ultraviolet irradiation are assigned to NF-2. The remaining absorptions are contributed by NF+3 and probably also by NF+2. Vibrational assignments for these absorptions are proposed, and processes which occur on mercury-arc irradiation of the deposit are considered.

Jacox, Marilyn E.; Thompson, Warren E.

1995-01-01

290

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

291

Multiphoton Imaging of Ultrasound Bioeffects in the Murine Brain  

NASA Astrophysics Data System (ADS)

The purpose of this study was to demonstrate the feasibility of multiphoton imaging in the murine brain during exposure to ultrasound. Our experimental setup coupled ultrasound through the ventral surface of the mouse while allowing imaging through a cranial window from the dorsal surface. Field attenuation was estimated by scanning the field after insertion of a freshly sacrificed mouse; beam profile and peak position were preserved, suggesting adequate targeting for imaging experiments. C57 mice were imaged with a Biorad multiphoton microscope while being exposed to ultrasound (f = 1.029 MHz, peak pressure ˜ 200 kPa, average power ˜ 0.18 W) with IV injection of Optison. We observed strong vasoconstriction coincident with US and Optison, as well as permeabilization of the blood-brain barrier.

Raymond, Scott; Skoch, Jesse; Bacskai, Brian; Hynynen, Kullervo

2006-05-01

292

Multichannel Multiphoton Imaging of Metal Oxides Nanoparticles in Biological System  

SciTech Connect

Near-IR ultrafast pulse laser and confocal microscope are combined to create a multiphoton multichannel non-linear imaging technique, which allows in situ 3-D characterization of nonfluorescent nanoparticles in biological systems. We observed intense CARS signals generated from various metal oxides due to their high third-order nonlinear susceptibilities (x(3)), which do not depend on the vibrational resonance but on the electronic resonance. We show that fine and ultrafine particles of metal oxides in alveolar macrophage cells may be imaged in vitro using CARS and multiphoton fluorescence microscopy with highest optical resolution for extended periods without photobleaching effects. The advantage of the epidetection over the forward detection for imaging sub-micron particles has been investigated.

Zheng, Yuangang; Holtom, Gary R.; Colson, Steve D.; Periasamy, A. and So, S.T.C.

2004-09-15

293

Multiphoton quantum interference with high visibility using multiport beam splitters  

NASA Astrophysics Data System (ADS)

Multiphoton states can be produced in multiple parametric down-conversion (PDC) processes. The nonlinear crystal in such a case is pumped with high power. In theory, the more populated these states are, the deeper is the conflict with local realistic description. However, the interference contrast in multiphoton PDC experiments can be quite low for high pumping. We show how the contrast can be improved. The idea employs currently accessible optical devices, the multiport beam splitters. They are capable of splitting the incoming light in one input mode to M output modes. Our scheme works as a positive operator-valued measure filter. It may provide a feasible Clauser-Horne-Shimony-Holt-Bell inequality test, and thus can be useful in, e.g., schemes reducing communication complexity.

Stobi?ska, Magdalena; Laskowski, Wies?aw; Wie?niak, Marcin; ?ukowski, Marek

2013-05-01

294

Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

295

Measurement-induced quantum operations on multiphoton states  

SciTech Connect

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.

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

296

Vectorizable wave propagation FORTRANcode for calculations of multiphoton dissociation  

NASA Astrophysics Data System (ADS)

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.

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

1992-06-01

297

Partial indistinguishability theory for multiphoton experiments in multiport devices  

NASA Astrophysics Data System (ADS)

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."

Shchesnovich, V. S.

2015-01-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

299

Cryogenic exciter  

DOEpatents

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.

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

2012-03-13

300

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

PubMed Central

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

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

301

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

PubMed

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

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

2014-02-13

302

Near-Infrared Excited State Dynamics of Melanins: The Effects of Iron Content, Photo-Damage, Chemical Oxidation, and Aggregate Size  

PubMed Central

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

2015-01-01

303

Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and  

E-print Network

LETTER Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser 16 July 2010 Key words: multiphoton processes; nonlinear microscopy; hand-held probe; fiber laser 1 multipho- ton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature

Chen, Zhongping

304

All optical histology of brain tissue: Serial ablation and multiphoton imaging with femtosecond laser pulses  

E-print Network

All optical histology of brain tissue: Serial ablation and multiphoton imaging with femtosecond pulses for serial histology. Successive iterations of multiphoton imaging and ablation provide techniques in histology involve the manual slicing of frozen or embedded tissue, which is both labor

Kleinfeld, David

305

Strong Field Multiphoton Inversion of a Three-Level System Using Shaped Ultrafast Laser Pulses  

NASA Astrophysics Data System (ADS)

We demonstrate strong-field population inversion in a three-level system with single and multiphoton coupling between levels using a single shaped ultrafast laser pulse. Our interpretation of the pulse shape dependence illustrates the difference between sequential population transfer and adiabatic rapid passage in three-level systems with multiphoton coupling between levels.

Clow, Stephen D.; Trallero-Herrero, Carlos; Bergeman, Thomas; Weinacht, Thomas

2008-06-01

306

Strong field multiphoton inversion of a three-level system using shaped ultrafast laser pulses.  

PubMed

We demonstrate strong-field population inversion in a three-level system with single and multiphoton coupling between levels using a single shaped ultrafast laser pulse. Our interpretation of the pulse shape dependence illustrates the difference between sequential population transfer and adiabatic rapid passage in three-level systems with multiphoton coupling between levels. PMID:18643499

Clow, Stephen D; Trallero-Herrero, Carlos; Bergeman, Thomas; Weinacht, Thomas

2008-06-13

307

Miniature random-access fiber scanner for in vivo multiphoton imaging  

Microsoft Academic Search

Multiphoton microscopy allows imaging of cellular activity in living tissue explants and in whole animals and has thus become a powerful tool for studying neuronal activity. The miniaturization of laser-scanning microscopy promises to extend activity measurements to awake, freely moving animals. Here we describe and evaluate a miniature multiphoton microscope based on a ``piezolever fiber scanner'' (PLFS). Our current PLFS

Jürgen Sawinski; Winfried Denk

2007-01-01

308

Exciting flavored bound states  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

309

Exciting flavored bound states  

E-print Network

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.

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

2014-10-23

310

Effect of laser spectral bandwidth on coherent control of resonance-enhanced multiphoton-ionization photoelectron spectroscopy  

SciTech Connect

The high-resolution (2 + 1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy (REMPI-PS) can be obtained by measuring the photoelectron intensity at a given kinetic energy and scanning the single ? phase step position. In this paper, we further demonstrate that the high-resolution (2 + 1) REMPI-PS cannot be achieved at any measured position of the kinetic energy by this measurement method, which is affected by the laser spectral bandwidth. We propose a double ? phase step modulation to eliminate the effect of the laser spectral bandwidth, and show the advantage of the double ? phase step modulation on achieving the high-resolution (2 + 1) REMPI-PS by considering the contributions involving on- and near-resonant three-photon excitation pathways.

Xu, Shuwu [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China) [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China); School of Science, Nantong University, Nantong 226007 (China); Ding, Jingxin, E-mail: jxding@phy.ecnu.edu.cn; Lu, Chenhui; Jia, Tianqing; Zhang, Shian, E-mail: sazhang@phy.ecnu.edu.cn; Sun, Zhenrong [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China)] [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China)

2014-02-28

311

Multiphoton microscopic imaging of histological sections without hematoxylin and eosin staining differentiates carcinoma in situ lesion from normal oesophagus  

NASA Astrophysics Data System (ADS)

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.

Chen, Jianxin; Xu, Jian; Kang, Deyong; Xu, Meifang; Zhuo, Shuangmu; Zhu, Xiaoqin; Jiang, Xingshan

2013-10-01

312

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual technical report, March 1991--February 1992  

SciTech Connect

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 state before it can decay. The overall objective of this effort is to carry out theoretical studies of these REMPI processes in molecules and molecular fragments which are designed to provide a robust analysis and prediction of key spectral features of interest in several experimental studies and applications of this technique. A specific and very important objective of the effort is to predict the vibrational and rotational ion distributions which result from REMPI of representative molecules and to understand the underlying mechanisms that give use to these ion distributions. The author highlights progress made during this period.

NONE

1993-12-31

313

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy.  

PubMed

Deep imaging in turbid media such as biological tissue is challenging due to scattering and optical aberrations. Adaptive optics has the potential to compensate the tissue aberrations. We present a wavefront sensing scheme for multi-photon scanning microscopes using the pulsed, near-infrared light reflected back from the sample utilising coherence gating and a confocal pinhole to isolate the light from a layer of interest. By interfering the back-reflected light with a tilted reference beam, we create a fringe pattern with a known spatial carrier frequency in an image of the back-aperture plane of the microscope objective. The wavefront aberrations distort this fringe pattern and thereby imprint themselves at the carrier frequency, which allows us to separate the aberrations in the Fourier domain from low spatial frequency noise. A Fourier analysis of the modulated fringes combined with a virtual Shack-Hartmann sensor for smoothing yields a modal representation of the wavefront suitable for correction. We show results with this method correcting both DM-induced and sample-induced aberrations in rat tail collagen fibres as well as a Hoechst-stained MCF-7 spheroid of cancer cells. PMID:24787857

van Werkhoven, T I M; Antonello, J; Truong, H H; Verhaegen, M; Gerritsen, H C; Keller, C U

2014-04-21

314

Infrared vibrational spectra of tert-butyl halides in dehydrated sodium-X and low-aluminum hydrogen-Y faujasites; vibrational excitation exchange and other effects of guest-host interactions  

NASA Astrophysics Data System (ADS)

Experimental, analytical and modeling techniques employed in this study elucidate interactions between adsorbate molecules and the interior surfaces of the porous faujasites (FAU). The vibrational spectroscopy of guest and host offers opportunities to locate the guest site in the host that can otherwise be approached only with low-temperature x-ray and neutron diffraction studies. Fourier transform infrared (FTIR) studies at 295 K of sodium X-type FAU (Na-X, Si/Al = 1.34, NaxSi(192-x)AlxO384) and low-aluminum acidic Y-type FAU (LAHY, Si/Al = 40, HxSi (192-x)AlxO384) supercage-included tert -butyl halides (CH3)3C-X (X = Cl, Br, I) are presented in comparison with the adsorbate molecular gas-phase and unloaded host solid-state spectra. For both FAU formula x = 1921+Si/Al . In the Na-X studies, four observations of tert-butyl halide (TBH) vibrational band changes (nu5, nu6, nu 7, and {nu3, nu16, nu17}, three of them concomitant with Na-X mode changes, together with computational modeling studies, point to a particular preferred siting of TBH at host hexagonal prisms (D6R). The siting involves simultaneous interactions of the host with methyl group axial protons and the halide atom. All three methyl group axial protons interact preferentially with a single D6R oxygen atom (type O1) via C-H···O bonding. The TBH halide atom interacts with a site III' Na cation. In addition, an exchange of quanta of vibrational excitation between TBH C-X stretching/CH 3 rocking skeletal mode nu5 and the Na-X Si-O-Si antisymmetric stretching band is observed. Analysis of the coalesced band is consistent with an interaction model involving one guest and one host mode. In the isostructural LAHY material, where cation-guest interactions are effectively absent, the weaker interactions of TBH with LAHY framework oxygen atoms are manifest in additional propensity toward the exchange of vibrational excitation quanta between both guest and host modes, and between two guest modes. In contrast to the Na-X results, the LAHY results reveal that guest-host vibrational excitation exchange is taking place between a single guest mode and multiple modes within a particular host band. This type of exchange phenomenon is observed for three different LAHY infrared bands. For both faujasite materials, the IR frequency shifts, exchange phenomena, pseudo-hydrogen bonding effects, and computational modeling studies are related to the siting of the guest molecules in the host supercages, and to the guest-host interactions at the guest sites.

Fox, Jack David

315

Monitoring chemically enhanced transdermal delivery of zinc oxide nanoparticles by using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

Zinc oxide nanoparticles (ZnO NPs) are commonly used in sunscreens to reduce the risk of skin cancer by blocking ultraviolet radiation. ZnO NPs absorption through the transdermal route may not cause high health risk as inhalation or ingestion. However, in practical usage of sunscreens and cosmetics, ZnO NPs are topically applied to a large area of skin with long periods hence the potential absorption amount of ZnO NPs is still need to be concerned. Therefore, if the ZnO NPs are able the pass the barrier of normal skin, the pathways of transdermal delivery and the factors of enhancements become important issues. In this work, multiphoton microscopy provides us a non-invasive visualization of ZnO NPs in skin. Moreover, we quantitatively analyzed the enhancement of oleic acid and ethanol. Due to the fact that photoluminance of ZnO NPs spectrally overlaps autofluorence from skin stratum corneum (SC) and high turbidity of both ZnO NPs and SC, it is difficult to resolve the distribution of ZnO NPs in skin by using fluorescence microscopy. In this work, the second harmonic generation (SHG) signals from ZnO NPs which double the frequency of excitation source to characterize the delivery pathways and penetration depth in skin. Moreover, we quantitatively compare the ZnO NPs delivery efficiency in normal skin and in skins with three chemically enhancing conditions: ethanol, oleic acid and the combination of ethanol and oleic acid.

Lo, Wen; Hsu, Chih-Ting; Kuo, Tsung-Rong; Wu, Chung-Long; Chiang, Shu-Jen; Lin, Sung-Jan; Chen, Shean-Jen; Chen, Chia-Chun; Dong, Chen-Yuan

2010-02-01

316

Extracellular oxygen concentration mapping with a confocal multiphoton laser scanning microscope and TCSPC card  

NASA Astrophysics Data System (ADS)

Extracellular oxygen concentrations influence cell metabolism and tissue function. Fluorescence Lifetime Imaging Microscopy (FLIM) offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods show limited spatial resolution and/or require custom made systems. This study describes a new optimised approach for quantitative extracellular oxygen detection, providing an off-the-shelf system with high spatial resolution and an improved lifetime determination over previous techniques, while avoiding systematic photon pile-up. Fluorescence lifetime detection of an oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)3]2+, was measured using a Becker&Hickl time-correlated single photon counting (TCSPC) card with excitation provided by a multi-photon laser. This technique was able to identify a subpopulation of isolated chondrocyte cells, seeded in three-dimensional agarose gel, displaying a significant spatial oxygen gradient. Thus this technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

Hosny, Neveen A.; Lee, David A.; Knight, Martin M.

2010-02-01

317

Identification of non-neoplastic and neoplastic gastric polyps using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

Gastric polyps can be broadly defined as luminal lesions projecting above the plane of the mucosal surface. They are generally divided into non-neoplastic and neoplastic polyps. Accurate diagnosis of neoplastic polyps is important because of their well-known relationship with gastric cancer. Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) is one of the most important recent inventions in biological imaging. In this study, we used MPM to image the microstructure of gastric polyps, including fundic gland polyps, hyperplastic polyps, inflammatory fibroid polyps and adenomas, then compared with gold-standard hematoxylin- eosin(H-E)-stained histopathology. MPM images showed that different gastric polyps have different gland architecture and cell morphology. Dilated, elongated or branch-like hyperplastic polyps are arranged by columnar epithelial cells. Inflammatory fibroid polyps are composed of small, thin-walled blood vessels surrounded by short spindle cells. Fundic glands polyps are lined by parietal cells and chief cells, admixed with normal glands. Gastric adenomas are generally composed of tubules or villi of dysplastic epithelium, which usually show some degree of intestinal-type differentiation toward absorptive cells, goblet cells, endocrine cells. Our results demonstrated that MPM can be used to identify non- neoplastic and neoplastic gastric polyps without the need of any staining procedure.

Jiang, Shanghai; Kang, Deyong; Xu, Meifang; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

2012-12-01

318

Clinical studies of pigmented lesions in human skin by using a multiphoton tomograph  

NASA Astrophysics Data System (ADS)

In vivo imaging of pigmented lesions in human skin was performed with a clinical multiphoton microscopy (MPM)-based tomograph (MPTflex, JenLab, Germany). Two-photon excited fluorescence was used for visualizing endogenous fluorophores such as NADH/FAD, keratin, melanin in the epidermal cells and elastin fibers in the dermis. Collagen fibers were imaged by second harmonic generation. Our study involved in vivo imaging of benign melanocytic nevi, atypical nevi and melanoma. The goal of this preliminary study was to identify in vivo the characteristic features and their frequency in pigmented lesions at different stages (benign, atypical and malignant) and to evaluate the ability of in vivo MPM to distinguish atypical nevi from melanoma. Comparison with histopathology was performed for the biopsied lesions. Benign melanocytic nevi were characterized by the presence of nevus cell nests at the epidermal-dermal junction. In atypical nevi, features such as lentiginous hyperplasia, acanthosis and architectural disorder were imaged. Cytological atypia was present in all the melanoma lesions imaged, showing the strongest correlation with malignancy. The MPM images demonstrated very good correlation with corresponding histological images, suggesting that MPM could be a promising tool for in vivo non-invasive pigmented lesion diagnosis, particularly distinguishing atypical nevi from melanoma.

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

2013-02-01

319

Strong field Multiphoton processes in the high-frequency limit  

NASA Astrophysics Data System (ADS)

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).

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

320

Partitioning of the Linear Photon Momentum in Multiphoton Ionization  

SciTech Connect

The balance of the linear photon momentum in multiphoton ionization is studied experimentally. In the experiment argon and neon atoms are singly ionized by circularly polarized laser pulses with a wavelength of 800 and 1400 nm in the intensity range of 10{sup 14}-10{sup 15} W/cm{sup 2}. The photoelectrons are measured using velocity map imaging. We find that the photoelectrons carry linear momentum corresponding to the photons absorbed above the field free ionization threshold. Our finding has implications for concurrent models of the generation of terahertz radiation in filaments.

Smeenk, C. T. L.; Villeneuve, D. M.; Staudte, A.; Corkum, P. B. [JASLab, University of Ottawa and National Research Council, 100 Sussex Drive, Ottawa (Canada); Arissian, L. [JASLab, University of Ottawa and National Research Council, 100 Sussex Drive, Ottawa (Canada); Department of Physics, Texas A and M University, College Station, Texas (United States); Zhou, B.; Mysyrowicz, A. [Laboratoire d'Optique Applique, ENSTA ParisTech-Ecole Polytechnique, 91761 Palaiseau (France)

2011-05-13

321

Statistics of multiphoton events in spontaneous parametric down-conversion  

E-print Network

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.

Wojciech Wasilewski; Czeslaw Radzewicz; Robert Frankowski; Konrad Banaszek

2008-05-12

322

Multiphoton ionization of ions, neutrals, and clusters. Final report  

SciTech Connect

A multiyear research program investigating molecular detection methods based on multiphoton spectroscopy has been completed under DOE sponsorship. A number of new laser-based spectroscopic methods were developed and applied to a variety of aromatic hydrocarbons, including monomer and cluster species. The objectives of sensitivities approaching single molecule detection combined with high selectivity were achieved. This report references the status of the field at the beginning of this work and summarizes the significant progress during the period from 1987 onward. Detailed scientific findings from the studies are presented in the published literature referenced throughout this report.

Wessel, J.

1995-12-28

323

Atomic force microscopy based, multiphoton, photoelectron emission imaging  

SciTech Connect

Images of photoelectron emission from metallic surfaces were obtained with a modified atomic force microscope operating in air. Illumination of the samples was achieved in the near field of a metal-coated microcantilever tip, placed in the beam of a femtosecond pulsed laser that is incident at a grazing angle with respect to the sample surface. Photoelectron currents were measured through the tip with a prototype amplifier. The power law dependence of average photocurrent on light intensity is compatible with multiphoton photoelectric effect and the work function of the metal covering a particular area on the two-metal patterned samples used.

Spanakis, E.; Chimmalgi, A.; Stratakis, E.; Grigoropoulos, C. P.; Fotakis, C.; Tzanetakis, P. [Institute of Electronic Structure and Lasers, Foundation for Research and Technology Hellas (IESL-FORTH), Heraklion 71110 (Greece); Materials Science and Technology Department, University of Crete, Heraklion 71003 (Greece); and Technological Educational Institute of Crete, Heraklion 71004 (Greece); Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Institute of Electronic Structure and Lasers, Foundation for Research and Technology Hellas (IESL-FORTH), Heraklion 71110 (Greece); Materials Science and Technology Department, University of Crete, Heraklion 71003 (Greece); and Technological Educational Institute of Crete, Heraklion 71004 (Greece); Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Institute of Electronic Structure and Lasers, Foundation for Research and Technology Hellas (IESL-FORTH), Heraklion 71110 (Greece) and Physics Department, University of Crete, Heraklion 71409 (Greece)

2006-07-03

324

Quantum Radiation Reaction Effects in Multiphoton Compton Scattering  

SciTech Connect

Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify the 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 the radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.

Di Piazza, A.; Hatsagortsyan, K. Z.; Keitel, C. H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

2010-11-26

325

Inherent contradictions in the tunneling-multiphoton dichotomy  

SciTech Connect

Strong-field phenomena are currently described as being multiphoton or tunneling, based on whether the Keldysh parameter {gamma} is greater than or less than unity. There are disqualifying features in this categorization. It is specific to the length gauge, dependent on only one intensity parameter, and backward in the sense that ionization with {gamma}>>1 can occur only by tunneling, and ionization with {gamma}<<1 must be over the barrier, and hence is not achieved by tunneling. As {gamma} becomes smaller, ionization becomes increasingly distant from tunneling, and eventually reaches conditions where the dipole approximation fails and there is no meaningful scalar-potential diagram at all.

Reiss, H. R. [Max Born Institute, 12489 Berlin, Germany and American University, Washington, DC 20016-8058 (United States)

2007-03-15

326

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.

327

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

PubMed Central

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.

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

328

Multiphoton imaging: a view to understanding sulfur mustard lesions  

NASA Astrophysics Data System (ADS)

It is well known that topical exposure to sulfur mustard (SM) produces persistent, incapacitating blisters of the skin. However, the primary lesions effecting epidermal-dermal separation and disabling of mechanisms for cutaneous repair remain uncertain. Immunofluorescent staining plus multiphoton imaging of human epidermal tissues and keratinocytes exposed to SM (400 ?M x 5 min)have revealed that SM disrupts adhesion-complex molecules which are also disrupted by epidermolysis bullosa-type blistering diseases of the skin. Images of keratin-14 showed early, progressive, postexposure collapse of the K5/K14 cytoskeleton that resulted in ventral displacement of the nuclei beneath its collapsing filaments. This effectively corrupted the dynamic filament assemblies that link basal-cell nuclei to the extracellular matrix via ?6?4-integrin and laminin-5. At 1 h postexposure, there was disruption in the surface organization of ?6?4 integrins, associated displacement of laminin-5 anchoring sites and a concomitant loss of functional asymmetry. Accordingly, our multiphoton images are providing compelling evidence that SM induces prevesicating lesions that disrupt the receptor-ligand organization and cytoskeletal systems required for maintaining dermal-epidermal attachment, signal transduction, and polarized mobility.

Werrlein, Robert J. S.; Madren-Whalley, Janna S.

2003-07-01

329

Scaling up multiphoton neural scanning: the SSA algorithm.  

PubMed

In order to reverse-engineer the information processing capabilities of the cortical circuit, we need to densely sample neural circuit; it may be necessary to sample the activity of thousands of neurons simultaneously. Frame scanning techniques do not scale well in this regard, due to the time "wasted" scanning extracellular space. For scanners in which inertia can be neglected, path length minimization strategies enable large populations to be imaged at relatively high sampling rates. However, in a standard multiphoton microscope, the scanners responsible for beam deflection are inertial, indicating that an optimal solution should take rotor and mirror momentum into account. We therefore characterized the galvanometric scanners of a commercial multiphoton microscope, in order to develop and validate a MATLAB model of microscope scanning dynamics. We tested the model by simulating scan paths across pseudo-randomly positioned neuronal populations of differing neuronal density and field of view. This model motivated the development of a novel scanning algorithm, Adaptive Spiral Scanning (SSA), in which the radius of a circular trajectory is constantly updated such that it follows a spiral trajectory scanning all the cells. Due to the kinematic efficiency of near-circular trajectories, this algorithm achieves higher sampling rates than shortest path approaches, while retaining a relatively efficient coverage fraction in comparison to raster or resonance based frame-scanning approaches. PMID:25570582

Schuck, Renaud; Annecchino, Luca A; Schultz, Simon R

2014-01-01

330

Rigid and high NA multiphoton fluorescence GRIN-endoscopes  

NASA Astrophysics Data System (ADS)

Multiphoton autofluorescence imaging offers minimal-invasive examination of cells without the need of staining and complicated confocal detection systems. Therefore, it is especially interesting for non-invasive clinical diagnostics. To extend this sophisticated technique from superficial regions to deep lying cell layers, internal body parts and specimens difficult of access, the bulky optics need to be reduced in diameter. This is done by tiny GRIN-optics, based on a radial gradient in the reflective index. Of especial interest for multi-photon applications is the newly developed GRIN-lens assembly with increased numerical aperture. High resolution images of plant tissue, hair and cells show the improved image quality,compared to classical GRIN-lenses. The rigid GRIN-endoscopes are already applied in wound healing studies. Here, the GRIN-lenses with diameters smaller than 3 mm enter small skin depressions. They reproduce the focus of a conventional laser scanning tomograph tens of mm apart in the specimen under study. We present first clinical measurements of elastin and SHG of collagen of in-vivo human skin of venous ulcers (ulcer curis).

Schenkl, Selma; Ehlers, Alexander; Le Harzic, Ronan; Stark, Martin; Riemann, Iris; Messerschmidt, Bernhard; Kaatz, Martin; König, Karsten

2007-07-01

331

Fringe-free, Background-free, Collinear Third Harmonic Generation FROG Measurements for Multiphoton Microscopy  

SciTech Connect

Collinear pulse measurement tools useful at the full numerical aperture (NA) of multiphoton microscope objectives are a necessity for a quantitative characterization of the femtosecond pulses focused by these systems. In this letter, we demonstrate a simple new technique, for characterizing the pulse at the focus in a multiphoton microscope. This technique, a background-free, fringe-free, form of frequency-resolved optical gating, uses the third harmonic signal generated from a glass coverslip. Here it is used to characterize 100 fs pulses (typical values for a multiphoton microscope) at the focus of a 0.65 NA objective.

Chadwick, R; Spahr, E; Squier, J A; Durfee, C G; Walker, B C; Fittinghoff, D N

2006-07-21

332

Theoretical studies of electronically excited states  

SciTech Connect

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.

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

2014-10-06

333

P cell excitability AP excitability  

E-print Network

AP (mV) P (mV) DP(15) (ipsi) DP(15) (contra) ba d P cell excitability Vm I (nA) AP excitability Vm) Measurement of input resistance of P and cell 212 and the amplitude of the P-to-cell 212 synaptic potential. We hyperpolarized cell 212 to prevent it from generating action potentials during P cell stimulations

Gaudry, Quentin

334

Infrared Investigations.  

ERIC Educational Resources Information Center

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)

Lascours, Jean; Albe, Virginie

2001-01-01

335

New Development of Theoretical and Computational Methods for Probing Strong-Field Multiphoton Processes  

E-print Network

The study of the strong-field multiphoton processes is a subject of much current significance in physics and chemistry. Recent progress of laser technology has triggered a burst of attosecond science where the electron dynamics plays a vital role...

Son, Sang-Kil

2009-12-02

336

Simultaneous imaging of GFP, CFP and collagen in tumors in vivousing multiphoton microscopy  

E-print Network

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 ...

Sahai, Erik

337

Wavelength Scaling of High Harmonic Generation Close to the Multiphoton Ionization Regime  

E-print Network

We study the wavelength scaling of high harmonic generation efficiency with visible driver wavelengths in the transition between the tunneling and the multiphoton ionization regimes where the Keldysh parameter is around ...

Lai, Chien-Jen

338

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

Microsoft Academic Search

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.

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

1977-01-01

339

A Method for Measuring Cerebral Blood Volume of Mouse using Multiphoton Laser Scanning Microscopy  

E-print Network

tumors, stroke, multiple sclerosis, neurodegenerative diseases, traumatic brain injury and epilepsy [1 by the development of multi-photon laser scanning microscopy, so that imaging of brain capillaries to a depth of 1000

Vial, Jean-Claude

340

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

341

Spectroscopy of atom and nucleus in a strong laser field: Stark effect and multiphoton resonances  

NASA Astrophysics Data System (ADS)

The consistent relativistic energy approach to atoms in a strong realistic laser field, based on the Gell-Mann and Low S-matrix formalism, is applied in the study of resonant multiphoton ionization of krypton by intense uv laser radiation and for the computation of the resonance shift and width in krypton. The approach to the treatment of the multiphoton resonances in nuclei is outlined for the 57Fe nucleus.

Glushkov, A. V.

2014-11-01

342

Reassignment of Scattered Emission Photons in Multifocal Multiphoton Microscopy  

PubMed Central

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

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

2014-01-01

343

Clinical multiphoton tomography and clinical two-photon microendoscopy  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

344

In vivo multiphoton tomography in skin aging studies  

NASA Astrophysics Data System (ADS)

High-resolution clinical multiphoton tomography based on the femtosecond laser system DermaInspect has been performed on hundreds of patients and volunteers in Australia, Asia, and Europe. The system enables the in vivo detection of the elastin and the collagen network as well as the imaging of melanin clusters in aging spots. The epidermis-dermis junction can be detected with submicron resolution. One major applications of this novel HighTech imaging tool is the determination of the skin aging index SAAID as well as the study of the effects of anti-aging products. In particular, the stimulated biosynthesis of collagen can be investigated over long periods of time. The system with its sub-500 nm lateral resolution is able to image age-related modifications of the extracellular matrix on the level of a single elastin fiber.

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

2009-02-01

345

Watching stem cells at work with a flexible multiphoton tomograph  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

346

Multi-photon absorption limits to heralded single photon sources  

PubMed Central

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

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

347

Multiphoton Microscopy and Interaction of Intense Light Pulses with Polymers  

NASA Astrophysics Data System (ADS)

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.

Guay, Jean-Michel

2011-07-01

348

Resonance Enhanced Multiphoton Ionization (rempi) Spectroscopy of Weakly Bound Complexes  

NASA Astrophysics Data System (ADS)

We have recently implemented Resonance Enhanced Multiphoton Ionization (REMPI) spectroscopy in our laboratory as a spectroscopic probe of transient species. We will report on initial gas-phase studies of the spectra of weakly bound van der Waals and halogen bonded complexes involving aromatic organic donors. The complexes are formed in the rarified environment of a supersonic molecular beam, which is skimmed prior to passing into the differentially pumped flight tube of a linear time-of-flight mass spectrometer. Ionization is initiated both by 1+1 and 1+1' REMPI schemes; the latter is used to minimize fragmentation. Our initial studies have examined van der Waals and halogen bonded complexes involving the phenol and toluene chromophores. Progress in the coupling of a discharge source into this apparatus will also be discussed.

Muzangwa, Lloyd; Nyambo, Silver; Uhler, Brandon; Reid, Scott A.

2012-06-01

349

Reassignment of scattered emission photons in multifocal multiphoton microscopy.  

PubMed

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

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

2014-01-01

350

Multi-photon absorption limits to heralded single photon sources.  

PubMed

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

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

351

Non-Gaussian features from Excited Squeezed Vacuum State  

E-print Network

In this work, we introduce a non-Gaussian quantum state named excited squeezed vacuum state (ESVS), which can be ustilized 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 Hilbert-Schmidt distance method, we quantify the non-Gaussianity of the ESVS. 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.

Xubing Tang; Fang Gao; Yaoxiong Wan; Jianguang Wu; Feng Shuang

2014-10-18

352

Scattering-theoretical approaches to multiphoton ionization in strong fields  

NASA Astrophysics Data System (ADS)

The nonrelativistic version of the authors' theory of multiphoton ionization [Phys. Rev. 40, 4997 (1989)] is compared with other forms of scattering-theoretical approaches that employ different boundary conditions. These methods, which are expressed in terms of formal time-independent scattering theory, are shown to be equivalent in the large-photon-number limit to use of the semiclassical time-dependent S-matrix theory. In the authors' treatment it is assumed that the photoelectron has escaped from both the electromagnetic and atomic fields; a perturbation expansion in the photon-electron interaction is obtained that correctly accounts for the atomic final-state interactions of the photoelectron. The case of multiphoton detachment of I- is treated, for which the influence of the final-state atomic potential on the transition rate can be ignored. It is shown both analytically and numerically for the Nd-yttrium aluminum garnet wavelength that the transition rates obtained for this case from the various approaches are distinctly different. The present approach is shown to be consistent with an abrupt switching off of a spatially unlimited monomode field, in contrast with Keldysh-type approaches, which correspond to a long switch-off time if the ad hoc assumption of ponderomotive acceleration is made. Above-threshold-ionization spectra calculated from the present approach exhibit interference effects and are redshifted with respect to what is expected for slow switch-off. It is demonstrated, using the semiclassical time-dependent approach, that the corresponding final off-field scattering-state wave function only exists if the ponderomotive potential per unit photon energy is an integer, in accordance with our earlier time-independent analysis. The origin of this curious feature is made clear.

Åberg, T.; Guo, D.-S.; Ruscheinski, J.; Crasemann, Bernd

1991-09-01

353

Transretinal degeneration in ageing human retina: a multiphoton microscopy analysis  

PubMed Central

Aim Retinal cell remodelling has been reported as a consistent feature of ageing. However, the degree to which this results in transretinal degeneration is unclear. To address this, the authors used multiphoton microscopy to quantify retinal degeneration in postmortem human eyes of two age groups. Methods Retinas from six young subjects (18–33 years old) and six older subjects (74–90 years old) were prepared as wholemount preparations. All retinas were stained with 4,6-diamidino-2-phenylindole and imaged by multiphoton confocal microscopy to quantify neuron densities in the retinal ganglion cell layer (RGCL), inner nuclear layer (INL) and outer nuclear layer (ONL). Neurons were counted using automated cell identification algorithms. All retinas were imaged hydrated to minimise tissue artefacts. Results In both groups, 56% of the area within the central 4 mm eccentricity and 27% of the area with eccentricity between 4 mm and 7 mm were imaged. Compared with young subjects, the peak RGCL neuron loss in the aged subjects (25.5%) was at 1 mm eccentricity. INL and ONL neuron densities significantly decreased at 1–2 mm eccentricity (8.7%) and 0.5–4 mm eccentricity (15.6%) respectively (P <0.05). The reduction in neuron density in the INL corresponded, spatially, to the region with the greatest neuron loss in the RGCL and ONL. Conclusions This is the first study to correlate neurodegeneration in different populations of cells in the ageing retinas. These data confirm that the greatest neuronal loss occurs in the RGCL and ONL in human ageing retinas, whereas the INL is relatively preserved. PMID:21183516

Lei, Y; Garrahan, N; Hermann, B; Fautsch, M P; Johnson, D H; Hernandez, M R; Boulton, M; Morgan, J E

2014-01-01

354

In vivo multiphoton microscopy associated to 3D image processing for human skin characterization  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy has emerged in the past decade as a promising non-invasive skin imaging technique. The aim of this study was to assess whether multiphoton microscopy coupled to specific 3D image processing tools could provide new insights into the organization of different skin components and their age-related changes. For that purpose, we performed a clinical trial on 15 young and 15 aged human female volunteers on the ventral and dorsal side of the forearm using the DermaInspectR medical imaging device. We visualized the skin by taking advantage of intrinsic multiphoton signals from cells, elastic and collagen fibers. We also developed 3D image processing algorithms adapted to in vivo multiphoton images of human skin in order to extract quantitative parameters in each layer of the skin (epidermis and superficial dermis). The results show that in vivo multiphoton microscopy is able to evidence several skin alterations due to skin aging: morphological changes in the epidermis and modifications in the quantity and organization of the collagen and elastic fibers network. In conclusion, the association of multiphoton microscopy with specific image processing allows the three-dimensional organization of skin components to be visualized and quantified thus providing a powerful tool for cosmetic and dermatological investigations.

Baldeweck, T.; Tancrède, E.; Dokladal, P.; Koudoro, S.; Morard, V.; Meyer, F.; Decencière, E.; Pena, A.-M.

2012-03-01

355

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

E-print Network

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

Fabio Dell'Anno; Silvio De Siena; Fabrizio Illuminati

2003-08-19

356

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

NASA Astrophysics Data System (ADS)

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.

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

357

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

PubMed

Multiphoton microscopy can instantly visualize cellular details in unstained tissues. Multiphoton probes with clinical potential have been developed. This study evaluates the suitability of multiphoton gradient index (GRIN) endoscopy as a diagnostic tool for prostatic tissue. A portable and compact multiphoton endoscope based on a 1-mm diameter, 8-cm length GRIN lens system probe was used. Fresh ex vivo samples were obtained from 14 radical prostatectomy patients and benign and malignant areas were imaged and correlated with subsequent H&E sections. Multiphoton GRIN endoscopy images of unfixed and unprocessed prostate tissue at a subcellular resolution are presented. We note several differences and identifying features of benign versus low-grade versus high-grade tumors and are able to identify periprostatic tissues such as adipocytes, periprostatic nerves, and blood vessels. Multiphoton GRIN endoscopy can be used to identify both benign and malignant lesions in ex vivo human prostate tissue and may be a valuable diagnostic tool for real-time visualization of suspicious areas of the prostate. PMID:25415446

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

358

Imaging-guided two-photon excitation-emission-matrix measurements of human skin tissues  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

359

Dual-spectrum laser source based on fiber continuum generation for integrated optical coherence and multiphoton microscopy  

PubMed Central

A single-laser dual-spectrum source designed for integrated optical coherence and multiphoton microscopy is demonstrated. The source implements the laser characteristics needed to optimally perform both modalities while extending the spectral range for this imaging technique. It consists of a widely tunable, mode-locked, Ti-sapphire laser with a portion of its output spectrally broadened via continuum generation in a photonic crystal fiber. The continuum-broadened beam allows for enhanced optical sectioning with optical coherence microscopy, while the unbroadened beam from the ultrashort-pulse Ti-sapphire laser optimally excites fluorescent markers. The noise power of the continuum-broadened beam is less than 1.1 dBm/Hz higher than the Ti-sapphire laser in the range from 1 Hz to 25 MHz, and the fiber shows no sign of damage after ~100 h of use. We demonstrate the use of this source across a wide spectral range by imaging green fluorescent protein-transfected mouse fibroblast cells costained with fluorescent dyes that are maximally excited at various wavelengths. Images of unstained in vivo human skin are also presented. This source extends the feasibility of this integrated imaging modality and will facilitate new investigations in in vivo microscopy, tissue engineering, and cell biology. PMID:19566312

Graf, Benedikt W.; Jiang, Zhi; Tu, Haohua; Boppart, Stephen A.

2010-01-01

360

Excited-state ions in femtosecond time-resolved mass spectrometry: an investigation of highly excited chloroamines.  

PubMed

We have investigated the processes induced by femtosecond laser pulses in chloroamines, with a focus on the generation and observation of a highly reactive radical and on the involvement and general importance of excited-state ions in time-resolved mass spectrometry investigations of gaseous molecules. We have found that 280 nm femtosecond pulses lead to an ultrafast breakage of the N-Cl bond on the repulsive S1 surface, and that resulting radical is long-lived. When exposing the molecule to 420 nm photons a multiphoton ionization takes place to generate ions; these ions can then be excited with a 280 nm photon. The evidence is unambiguous since we observe a distinct temporal evolution of the ion current with no photoelectrons to match. We suggest that the involvement of excited-state ions is a general phenomenon in time-resolved photoionization studies. PMID:19072070

Rusteika, Nerijus; Brogaard, Rasmus Y; Sølling, Theis I; Rudakov, Fedor M; Weber, Peter M

2009-01-01

361

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

E-print Network

, France Abstract Protonated dialanine cations have been isolated in a Fourier transform ion cyclotron protonated ions, produced by MALDI, are first stored and mass-selected in a Fourier transform ion cyclotron) is a very efficient process for deposition of energy in an isolated peptide cation leading to its

Paris-Sud XI, Université de

362

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

E-print Network

rot B XaOt 17 + U a"'J-E:8 Xii", u = L.J ",a' X6Ot' u • a'~ (30) Since all the P bands possess the same QVE structure to within a phase factor, only one P band needs to be considered. For convenience we shall choose the P = 0 band below...

Ho, Tak-San; Chu, Shih-I

1983-07-14

363

Infrared SETI  

Microsoft Academic Search

SETI at infrared wavelengths is discussed, and relative advantages or disadvantages of searches at various wavelengths, including microwave SETI, are analyzed. The mid-infrared appears to be one of the most favorable regions for a SETI.

Charles H. Townes

1993-01-01

364

Infrared Gallery  

NSDL National Science Digital Library

How would your world look if you saw heat instead of light? In this interactive resource produced for Teachers' Domain, see what familiar objects look like through an infrared camera and watch infrared videos of geysers, mudpots, and hot springs.

WGBH Educational Foundation

2005-10-21

365

Infrared Waves  

NSDL National Science Digital Library

This webpage, part of a National Aeronautics and Space Administration's site on the electromagnetic spectrum, presents information on infrared light. An explanation of how objects emit infrared is provided, along with a diagram of the electromagnetic spectrum. The site contains a number of photos made with infrared light.

366

Excited Delirium  

PubMed Central

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

Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

2011-01-01

367

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

E-print Network

Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper ``Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states'', 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 non degenerate and degenerate multiphoton processes. We determine the coherent states associated to the canonical transformations, which generalize the non degenerate two--photon squeezed states. Such heterodyne multiphoton squeezed 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 non classical, 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.

Fabio Dell'Anno; Silvio De Siena; Fabrizio Illuminati

2003-08-18

368

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

SciTech Connect

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.

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

369

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

NASA Astrophysics Data System (ADS)

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.

dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

2004-03-01

370

Tunneling Dynamics in Multiphoton Ionization and Attoclock Calibration  

NASA Astrophysics Data System (ADS)

The intermediate domain of strong-field ionization between the tunneling and multiphoton regimes is investigated using the strong-field approximation and the imaginary-time method. An intuitive model for the dynamics is developed which describes the ionization process within a nonadiabatic tunneling picture with a coordinate dependent electron energy during the under-the-barrier motion. The nonadiabatic effects in the elliptically polarized laser field induce a transversal momentum shift of the tunneled electron wave packet at the tunnel exit and a delayed appearance in the continuum as well as a shift of the tunneling exit towards the ionic core. The latter significantly modifies the Coulomb focusing during the electron excursion in the laser field after exiting the ionization tunnel. We show that nonadiabatic effects are especially large when the Coulomb field of the ionic core is taken into account during the under-the-barrier motion. The simple man model modified with these nonadiabatic corrections provides an intuitive background for exact theories and has direct implications for the calibration of the attoclock technique.

Klaiber, Michael; Hatsagortsyan, Karen Z.; Keitel, Christoph H.

2015-02-01

371

Multiphoton imaging the disruptive nature of sulfur mustard lesions  

NASA Astrophysics Data System (ADS)

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.

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

2005-03-01

372

Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes  

NASA Astrophysics Data System (ADS)

The aqueous outflow system (AOS), including the trabecular meshwork (TM), the collector channels (CC) and the Schlemm's canal (SC), regulates intraocular pressure (IOP) through the drainage of the aqueous humor (AH). Abnormal IOP elevation leads to increased pressure stress to retinal ganglion cells, resulting in cell loss that can ultimately lead to complete loss of eyesight. Therefore, development of imaging tools to detect abnormal structural and functional changes of the AOS is important in early diagnosis and prevention of glaucoma. Multiphoton microscopy (MPM), including twophoton autofluorescence (TPAF) and second harmonic generation (SHG), is a label-free microscopic technique that allows molecular specific imaging of biological tissues like the TM. Since the TM and other AOS structures are located behind the highly scattering scleral tissue, transscleral imaging of the TM does not provide enough optical resolution. In this work, a gonioscopic lens is used to allow direct optical access of the TM through the cornea for MPM imaging. Compared to transscleral imaging, the acquired MPM images show improved resolution as individual collagen fiber bundles of the TM can be observed. MPM gonioscopy may have the potential to be developed as a future clinical imaging tool for glaucoma diagnostics.

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

2013-03-01

373

The analysis of aging skin based on multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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.

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

2010-11-01

374

Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

375

A new approach for fast, simultaneous NO/NO2 analysis: application of basic features of multiphoton-induced ionization and dissociation of NO(x).  

PubMed

A new method of simultaneously recording NO and NO2 concentrations in complex gas mixtures is described. This method is based on resonance enhanced multiphoton ionization (REMPI), on time-of-flight mass analysis, and on monitoring the kinetic energy released upon dissociation of NO2. Its benefits are high speed and high flexibility. NO/NO2 analysis can therefore be combined with the simultaneous monitoring of other components. For instance, NH3 is a compound of interest when studying the chemical reactions of NO(x) in catalytic converters of combustion engines. The spectroscopic excitation schemes used for this new method are discussed in detail. Its reliability has been demonstrated by performing measurements at an industrial motor test facility. This novel technique performs well in comparison with conventional NO(x) analysis using chemiluminescence detection. PMID:16328245

Bornschlegl, A; Weishaeupl, R; Boesl, U

2006-01-01

376

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

PubMed

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

Wilson, Jesse W; Park, Jong Kang; Warren, Warren S; Fischer, Martin C

2015-03-01

377

Multiphoton processes in the field of two-frequency circularly polarized plane electromagnetic waves  

SciTech Connect

The authors solve Dirac`s equation for an electron in the field of a two-frequency plane electromagnetic wave, deriving general formulae for the probabilities of radiation of a photon by the electron, and for the probabilities for pair production by a photon when the two-frequency wave is circularly polarized. In contrast to the case of a monochromatic-plane electromagnetic wave, when an electron is in the field of a two-frequency circularly polarized wave, besides the absorption of multiphotons and emission of simple harmonics of the individual waves, stimulated multiphoton emission processes and various composite harmonic-photon emission processes are occurred: when a high-energy photon is in a such a field, multiphoton processes also follow the pair production processes.

Yu, An [Brookhaven National Lab., Upton, NY (United States)]|[Tsinghua Univ., Beijing (China). Physics Dept.; Takahashi, H. [Brookhaven National Lab., Upton, NY (United States)

1997-07-01

378

Two-photon imaging of intact living plants during freezing with a flexible multiphoton tomograph  

NASA Astrophysics Data System (ADS)

We describe the combination of a flexible multiphoton tomograph (MPTflex) with a heating and cooling stage. The stage allows temperature control in the range of (?196?°C) (77?K) to +600?°C (873?K) with selectable heating/freezing rates between 0.01?K?min?1 and 150?K?min?1. To illustrate the imaging capabilities of the combined system, fluorescence intensity and lifetime of intrinsic molecules from a plant leaf were imaged with submicron resolution during freezing in vivo without detaching the leaf from the plant. An increase of fluorescence intensity and decay times with decreasing temperature was observed. The measurements illustrate the usefulness of multiphoton imaging as a non-invasive online tool to investigate temperature-induced effects. The flexible multiphoton tomograph with its adjustable mechano-optical arm and scan head allows imaging at otherwise hardly accessible sample regions.

Breunig, H. G.; König, K.

2015-02-01

379

Processing multiphoton states through operation on a single photon: Methods and applications  

SciTech Connect

Multiphoton states are widely applied in quantum information technology. By the methods presented in this paper, the structure of a multiphoton state in the form of multiple single-photon qubit products can be mapped to a single-photon qudit, which could also be in a separable product with other photons. This makes possible the manipulation of such multiphoton states by processing single-photon states. The optical realization of unknown qubit discrimination [B. He, J. A. Bergou, and Y.-H. Ren, Phys. Rev. A 76, 032301 (2007)] is simplified with the transformation methods. Another application is the construction of quantum logic gates, where the inverse transformations back to the input state spaces are also necessary. We especially show that the modified setups to implement the transformations can realize the deterministic multicontrol gates (including Toffoli gate) operating directly on the products of single-photon qubits.

Lin Qing [College of Information Science and Engineering, Huaqiao University (Xiamen), Xiamen 361021 (China); He Bing [Institute for Quantum Information Science, University of Calgary, Alberta, T2N 1N4 (Canada); Bergou, Janos A.; Ren, Yuhang [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States)

2009-10-15

380

Infrared Astronomy  

NSDL National Science Digital Library

Despite the claims of certain science fiction novels and films, humans cannot see in infrared. As many people know, the primary source of infrared radiation is heat, and the study of infrared astronomy allows scientists to detect radiation emitted from objects throughout the universe. This delightful website (created by NASA and the Infrared Processing and Analysis Center at the California Institute of Technology) provides a wide range of material on this fascinating area of scientific study. Visitors can lean about the discovery of infrared, learn about the technology that is used in such endeavors, and of course, look over dozens of infrared images and video clips. Educators will be glad to learn that there are a number of activities offered here for use in the classroom, including one that will help students learn how to build a photocell detector.

Hermans-Killam, Linda

381

Excited state dynamics of Photoactive Yellow Protein chromophores elucidated by high-resolution spectroscopy and ab initio calculations.  

PubMed

We report on experimental high-resolution spectroscopic studies in combination with advanced theoretical calculations that focus on the excited-state dynamics of various forms of the chromophore of the Photoactive Yellow Protein (PYP), and the dependence of these dynamics on conformational and isosteric structure, as well as the biological environment. Three-colour nanosecond multiphoton ionization pump-probe studies confirm and extend previous conclusions that the dominant decay channel of the lowest excited pipi* state (the so-called V' state) of methyl-4-hydroxycinnamate is picosecond internal conversion to the adiabatically lower nPi* state, and enable us to resolve apparent contradictions with picosecond pump-probe studies. Comparison of multiphoton ionization and laser induced fluorescence excitation spectra leads to the assignment of the hitherto elusive excitation spectrum of the V(pipi*) state. Complexation of methyl-4-hydroxycinnamate with water radically changes the excited-state dynamics; internal conversion to the npi* state is absent, and bond isomerization channels instead play a prominent role. Excited states of the thio-ester compound, the form in which the chromophore is present in PYP, have till the present study remained out of reach of gas-phase studies. The excitation spectra obtained here show a broad, almost structureless band system, giving evidence for enhanced nonradiative decay channels. The gas-phase results will be discussed in the context of results from ultrafast studies on these two chromophores in solution. PMID:24020209

Tan, Eric M M; Amirjalayer, Saeed; Bakker, Bert H; Buma, Wybren J

2013-01-01

382

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

E-print Network

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.

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

2015-03-19

383

Demonstration of structural alterations in experimental corneal infectious model using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

The aim of this study is to assess the application of multiphoton autofluorescence and second harmonic generation (SHG) microscopy for investigating the structural alterations and the pattern of microbial spreading during corneal infectious process in an in vitro organ culture model. The autofluorescence spectrum derived from pathogens allows us to monitoring the pattern of microbial spreading within corneal lamellae. In addition, the destruction and regeneration of second harmonic generating collagen during infectious process can also be monitored in a non-invasive fashion. Therefore we propose that multiphoton microscopy may potentially be applied as an effective monitoring tool for corneal infection studies.

Lo, Wen; Tan, Hsin-Yuan; Chang, Yuh-Ling; Sun, Yen; Lin, Sung-Jan; Jee, Shiou-Hwa; Dong, Chen-Yuan

2007-02-01

384

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

SciTech Connect

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.

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

385

Miniature random-access fiber scanner for in vivo multiphoton imaging  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy allows imaging of cellular activity in living tissue explants and in whole animals and has thus become a powerful tool for studying neuronal activity. The miniaturization of laser-scanning microscopy promises to extend activity measurements to awake, freely moving animals. Here we describe and evaluate a miniature multiphoton microscope based on a "piezolever fiber scanner" (PLFS). Our current PLFS has a scan range of 1.1 mm and a resonance frequency of 790 Hz. It allows, unlike resonance-based designs, a lateral shift of the scanned area, and offers the prospect of random-access (vector) scanning.

Sawinski, Jürgen; Denk, Winfried

2007-08-01

386

Multifocal, multi-modal, photon counting, multiphoton microscopy  

Microsoft Academic Search

High-speed nonlinear imaging systems capable of dynamically imaging multiple focal planes simultaneously, in multiple modalities (two photon excitation fluorescence, second harmonic generation, and third harmonic generation), are demonstrated for the first time.

Jeff A. Squier; W. Amir; Ramon Carriles; E. Chandler; J. J. Field; E. E. Hoover; D. Schafer; K. E. Sheetz

2009-01-01

387

Assessment of liver steatosis and fibrosis in rats using integrated coherent anti-Stokes Raman scattering and multiphoton imaging technique  

NASA Astrophysics Data System (ADS)

We report the implementation of a unique integrated coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and two-photon excitation fluorescence (TPEF) microscopy imaging technique developed for label-free monitoring of the progression of liver steatosis and fibrosis generated in a bile duct ligation (BDL) rat model. Among the 21 adult rats used in this study, 18 rats were performed with BDL surgery and sacrificed each week from weeks 1 to 6 (n = 3 per week), respectively; whereas 3 rats as control were sacrificed at week 0. Colocalized imaging of the aggregated hepatic fats, collagen fibrils, and hepatocyte morphologies in liver tissue is realized by using the integrated CARS, SHG, and TPEF technique. The results show that there are significant accumulations of hepatic lipid droplets and collagen fibrils associated with severe hepatocyte necrosis in BDL rat liver as compared to a normal liver tissue. The volume of normal hepatocytes keeps decreasing and the fiber collagen content in BDL rat liver follows a growing trend until week 6; whereas the hepatic fat content reaches a maximum in week 4 and then appears to stop growing in week 6, indicating that liver steatosis and fibrosis induced in a BDL rat liver model may develop at different rates. This work demonstrates that the integrated CARS and multiphoton microscopy imaging technique has the potential to provide an effective means for early diagnosis and detection of liver steatosis and fibrosis without labeling.

Lin, Jian; Lu, Fake; Zheng, Wei; Xu, Shuoyu; Tai, Dean; Yu, Hanry; Huang, Zhiwei

2011-11-01

388

Kinetic modeling of evolution of 3?+?1:Resonance enhanced multiphoton ionization plasma in argon at low pressures  

SciTech Connect

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.

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

389

Infrared Thermometers  

NSDL National Science Digital Library

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.

John Schaefers

2006-01-01

390

Studies of laser selective excitation of atoms  

NASA Astrophysics Data System (ADS)

Sample preparation through laser ablation of a solid target under vacuum was combined with short-pulsed laser selective excitation to create a technique for measuring atomic radiative lifetimes. The lifetimes of the three resonance states of chromium compare very favorably with those found through other experimental means. The technique was extended to demonstrate the potential for plasma dianostics using two-wavelength selective excitation with short laser pulses. The ratio of population densities of two energy states of chromium atoms was measured as a function of time during the expansion of the ablation plasma. Extended saturation pumping of the resonance transition in sodium vapor was also investigated. Rate equations for 20 energy levels in the sodium atom, and the rate equations for the free electrons ,were integrated numerically. It was found that multiphoton ionization, combined with superelastic heating of free electrons can account for the rapid and complete ionization of an un-ionized vapor. The theoretical results led to the development of a simple model which accurately predicts the temporal variation of electron density.

Drewell, N.

1979-12-01

391

Studies of laser selective excitation of atoms  

NASA Astrophysics Data System (ADS)

Sample preparation through laser ablation of a solid target under vacuum has been combined with short-pulsed laser selective excitation to create a new and convenient experimental technique for measuring atomic radiative lifetimes. The lifetimes of the three resonance states of chromium determined in this way compare very favourably with those found through other experimental means. In addition, the technique has been extended to demonstrate experimentally the potential for plasma diagnostics using two-wavelength selective excitation with short laser pulses. The ratio of population densities of two energy states of chromium atoms has been measured as a function of time during the expansion of the ablation plasma. Extended saturation pumping of the resonance transition in sodium vapour has been investigated theoretically. Rate equations for 20 energy levels in the sodium atom, and the rate equations for the free electrons, were integrated numerically. It has been found that multiphoton ionization, combined with superelastic heating of free electrons can account for the rapid and complete ionization of an un-ionized vapour, as reported in the literature. The detailed theoretical results have led to the development of a simple model which accurately predicts the temporal variation of electron density.

Drewell, N.

1979-12-01

392

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)

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.

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

2014-10-01

393

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

PubMed Central

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

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

394

Development of a powerful tool for nanostructuring and multiphoton imaging with nanojoule femtosecond laser pulses  

Microsoft Academic Search

An integrated tool combining control and diagnostic for nanoprocessing of bio-compatible and biological materials and also allowing multiphoton large area laser scanning microscopy has been developed. The device is based on an customized inverted microscope integrating a motorized open x,y stage with a very high precision and repeatability, a piezoelectric z axe. A strong development in hardware and software has

D. Bruneel; M. Schwarz; E. Audouard; K. König; R. Le Harzic

2009-01-01

395

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

SciTech Connect

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.

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

396

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

397

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Technical report, January 1990--December 1990  

SciTech Connect

The objective of our effort is to carry out theoretical studies of resonance enhanced multiphoton ionization processes in molecules and molecular fragments. These studies are designed to provide a quantitatively robust analysis and prediction of key spectral features of interest in several ongoing experimental studies and applications of this technique.

NONE

1997-07-01

398

All optical histology : Serial ablation and multiphoton imaging of neuronal tissue with femtosecond laser pulses  

E-print Network

All optical histology : Serial ablation and multiphoton imaging of neuronal tissue with femtosecond pulses to serially image and ablate neuronal tissue. This allows histological imaging throughout techniques in histology involve the manual slicing of frozen or embedded tissue, which is labor intensive

Kleinfeld, David

399

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

E-print Network

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

Thumm, Uwe

400

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

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

401

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

NASA Astrophysics Data System (ADS)

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.

dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

2004-03-01

402

Resonant multiphoton ionization spectra of molecules and molecular fragments. Technical progress report  

SciTech Connect

objectives of this research are the development and application of theoretical techniques for studying several resonant multiphoton ionization processes in molecules. Specific problems of interest pertain to experimental studies of such spectra in which the photoelectron energy and angular distributions are determined.

NONE

1997-07-01

403

Pharmacophotonics: Utilizing multi-photon microscopy to quantify drug delivery and intracellular trafficking in the kidney  

Microsoft Academic Search

The recent introduction of multi-photon microscopy coupled with advances in optics, computer sciences and the available fluorophores used to label molecules of interest have empowered investigators to study the dynamic events within the functioning kidney at cellular and subcellular levels. This emerging technique, with improved spatial and temporal resolution and sensitivity, enables investigators to follow the cell specific uptake of

Bruce A. Molitoris; Ruben M. Sandoval

2006-01-01

404

Remote sensing by infrared heterodyne spectroscopy  

NASA Technical Reports Server (NTRS)

The use of infrared heterodyne spectrocopy for the study of planetary atmospheres is discussed. Infrared heterodyne spectroscopy provides a convenient and sensitive method for measuring the true intensity profiles of atmospheric spectral lines. Application of radiative transfer theory to measured lineshapes can then permit the study of molecular abundances, temperatures, total pressures, excitation conditions, and dynamics of the regions of line formation. The theory of formation of atmospheric spectral lines and the retrieval of the information contained in these molecular lines is illustrated. Notable successes of such retrievals from infrared heterodyne measurements on Venus, Mars, Jupiter and the Earth are given. A discussion of developments in infrared heterodyne technology is also presented.

Kostiuk, T.; Mumma, M. J.

1983-01-01

405

Infrared Measurement  

NASA Technical Reports Server (NTRS)

A Jet Propulsion Laboratory Technical Support Package (TSP) describing a technique for processing data from an infrared radiometer assisted a manufacturer of laminates for printed circuit boards. To reduce emissions and lower the cost of producing prepreg (a continuous glass cloth, or web, impregnated with epoxy resin and partially cured by applying heat), Norplex Oak switched to infrared treating towers. The TSP confirmed the company's computer prediction of heat flux patterns, provided information that allowed the company to modify infrared treaters for consistency, and furnished a basis for development of optimal heater placements. The treaters are now successfully operating at increased speeds with improved product consistency.

1992-01-01

406

Infrared monitoring of the Space Station environment  

NASA Technical Reports Server (NTRS)

The measurement and monitoring of infrared emission in the environment of the Space Station has a twofold importance - for the study of the phenomena itself and as an aid in planning and interpreting Station based infrared experiments. Spectral measurements of the infrared component of the spacecraft glow will, along with measurements in other spectral regions, provide data necessary to fully understand and model the physical and chemical processes producing these emissions. The monitoring of the intensity of these emissions will provide background limits for Space Station based infrared experiments and permit the determination of optimum instrument placement and pointing direction. Continuous monitoring of temporal changes in the background radiation (glow) will also permit better interpretation of Station-based infrared earth sensing and astronomical observations. The primary processes producing infrared emissions in the Space Station environment are: (1) Gas phase excitations of Station generated molecules ( e.g., CO2, H2O, organics...) by collisions with the ambient flux of mainly O and N2. Molecular excitations and generation of new species by collisions of ambient molecules with Station surfaces. They provide a list of resulting species, transition energies, excitation cross sections and relevant time constants. The modeled spectrum of the excited species occurs primarily at wavelengths shorter than 8 micrometer. Emissions at longer wavelengths may become important during rocket firing or in the presence of dust.

Kostiuk, Theodor; Jennings, Donald E.; Mumma, Michael J.

1988-01-01

407

Why Infrared?  

ERIC Educational Resources Information Center

Discusses applications of techniques developed for the remote sensing of infrared radiation. In addition to military applications, remote sensing has become important in collecting environmental data and detecting ecological problems. (JR)

Harris, J. R.

1973-01-01

408

Seeing Infrared.  

ERIC Educational Resources Information Center

Provides directions for building a comparatively inexpensive device that detects and displays images of infrared light sources. Includes typical costs for the components, an artist's sketch of the finished product, and suggestions for adjustments and image recordings. (JJK)

Mooney, Donald

1992-01-01

409

Controlling film growth with selective excitation: Chemical vapor deposition growth of silicon  

E-print Network

early that one could utilize the selective excitation for efficient isotope separation at surfaces;8 and steps. With a properly tuned infrared laser, one can selectively excite only the adatom­substrate bonds method, we take advantage of the geomet- ric frequency difference at a surface and use an infrared laser

Cohen, Philip I.

410

Light emission of very low density hydrogen excited by an extremely hot light source; applications in astrophysics  

E-print Network

Stromgren studied the action of an extremely hot source on a diluted pure hydrogen cloud; a very ionized, spherical hydrogen plasma surrounded by neutral atomic hydrogen is formed. A relatively thin intermediate, partially ionized, hydrogen shell, is cooled by the radiation of the atoms. Stromgren was unaware of that this plasma, similar to the plasma of a gas laser, can be superradiant at several eigen frequencies of atomic hydrogen; the superradiant rays emitted tangentially with the sphere appear resulting from a discontinuous ring because of the competition of optical modes. The superradiance intensely depopulates the excited levels, including the continuum of proton-electron collisions, by cascades of transitions combined into resonant multiphotonic transitions so that the gas is cooled brutally beyond the radius of the Stromgren sphere. The extreme brightness of the rays emitted by the source allows a multiphotonic non-resonant absorption leading in stationary states or the ionization continuum. This absorption combines with the superradiant emissions in a multiphotonic diffusion induced by the superradiant rays. Although its brightness remains higher than that of the superradiant rays, the source becomes invisible if it is observed through a small solid angle. The lines emitted inside the sphere are all the more weak as they arrive of an internal area, lower in atoms, and more reddened also by a parametric transfer of energy towards the thermal radiation catalyzed by excited atomic hydrogen present in the sphere only. The Stromgren sphere appears to help to simply explain the appearance and the spectrum of supernova 1987A.

Jacques Moret-Bailly

2008-07-19

411

Resonant multiphoton ionization for the detection of technetium  

SciTech Connect

Experiments were carried out to determine optimum wavelengths for the selective ionization of technetium and to estimate the ultimate sensitivity obtainable for resonant ionization mass spectrometry detection of Tc in real samples. Results indicated that the 3099 and 3098 A lines may be analytically useful. The rate of ion production by laser excitation using pulsed lasers and techniques for volatilization of the sample are discussed. (MCG)

Nogar, N.N.; Miller, C.M.; Downey, S.W.; Sander, R.K.

1983-01-01

412

Ligand-field excited states of hexacyanochromate and hexacyanocobaltate as sensitisers for near-infrared luminescence from Nd(iii) and Yb(iii) in cyanide-bridged d-f assemblies.  

PubMed

Crystallisation of [Co(CN)(6)](3-) or [Cr(CN)(6)](3-) with Ln(iii) salts (Ln = Nd, Gd, Yb) from aqueous dmf afforded the cyanide-bridged d/f systems [Ln(dmf)(4)(H(2)O)(3)(micro-CN)Co(CN)(5)] (-, discrete dinuclear species) and {[Cr(CN)(4)(micro-CN)(2)Ln(H(2)O)(2)(dmf)(4)]}(infinity) (-, infinite cyanide-bridged chains with alternating Cr and Ln centres). With Ln = Gd the characteristic long-lived phosphorescence from d-d excited states of the [M(CN)(6)](3-) units was apparent in the red region of the spectrum, with lifetimes of the order of 1 micros, since the heavy atom effect of the Gd(iii) promotes inter-system crossing at the [M(CN)(6)](3-) units to generate the phosphorescent spin-forbidden excited states. With Ln = Yb or Nd however, the d-block luminescence was completely quenched due to fast (>10(8) s(-1)) energy-transfer to the Ln(iii) centre, resulting in the characteristic sensitised emission from Yb(iii) and Nd(iii) in the near-IR region. For both - and -, calculations based on spectroscopic overlap between emission of the donor (Co) and absorption of the acceptor (Ln) suggest that the Dexter energy-transfer mechanism is responsible for the complete quenching that we observe. PMID:17973046

Lazarides, Theodore; Davies, Graham M; Adams, Harry; Sabatini, Cristiana; Barigelletti, Francesco; Barbieri, Andrea; Pope, Simon J A; Faulkner, Stephen; Ward, Michael D

2007-11-01

413

Infrared Camera  

NASA Technical Reports Server (NTRS)

A sensitive infrared camera that observes the blazing plumes from the Space Shuttle or expendable rocket lift-offs is capable of scanning for fires, monitoring the environment and providing medical imaging. The hand-held camera uses highly sensitive arrays in infrared photodetectors known as quantum well infrared photo detectors (QWIPS). QWIPS were developed by the Jet Propulsion Laboratory's Center for Space Microelectronics Technology in partnership with Amber, a Raytheon company. In October 1996, QWIP detectors pointed out hot spots of the destructive fires speeding through Malibu, California. Night vision, early warning systems, navigation, flight control systems, weather monitoring, security and surveillance are among the duties for which the camera is suited. Medical applications are also expected.

1997-01-01

414

Infrared Scanning  

NASA Technical Reports Server (NTRS)

United Scanning Technologies, Inc.'s Infrared thermography is a relatively new noncontact, nondestructive inspection and testing tool which makes temperatures visible to the human eye. Infrared scanning devices produce images that show, by color or black and white shading differences, heat losses through damaged or inadequately insulated walls or roofs. The MISS Aeroscan services are designed to take the guesswork out of industrial roof maintenance and provide companies big savings by identifying the location of moisture damage from roof leaks, effectively targeting maintenance attention.

1987-01-01

415

Infrared Thermometer  

NASA Technical Reports Server (NTRS)

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.

1991-01-01

416

Infrared astronomy  

NASA Technical Reports Server (NTRS)

The decade of 1990's presents an opportunity to address fundamental astrophysical issues through observations at IR wavelengths made possible by technological and scientific advances during the last decade. The major elements of recommended program are: the Space Infrared Telescope Facility (SIRTF), the Stratospheric Observatory For Infrared Astronomy (SOFIA) and the IR Optimized 8-m Telescope (IRO), a detector and instrumentation program, the SubMilliMeter Mission (SMMM), the 2 Microns All Sky Survey (2MASS), a sound infrastructure, and technology development programs. Also presented are: perspective, science opportunities, technical overview, project recommendations, future directions, and infrastructure.

Gillett, Frederick; Houck, James; Bally, John; Becklin, Eric; Brown, Robert Hamilton; Draine, Bruce; Frogel, Jay; Gatley, Ian; Gehrz, Robert; Hildebrand, Roger

1991-01-01

417

FAR-INFRARED SPECTROSCOPY OF CATIONIC POLYCYCLIC AROMATIC HYDROCARBONS: ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY OF PENTACENE VAPORIZED FROM LASER DESORPTION  

SciTech Connect

The distinctive set of infrared (IR) emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are ubiquitously seen in a wide variety of astrophysical environments. They are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. However, not a single PAH species has yet been identified in space, as the mid-IR vibrational bands are mostly representative of functional groups and thus do not allow one to fingerprint individual PAH molecules. In contrast, the far-IR (FIR) bands are sensitive to the skeletal characteristics of a molecule, hence they are important for chemical identification of unknown species. With an aim to offer laboratory astrophysical data for the Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and similar future space missions, in this work we report neutral and cation FIR spectroscopy of pentacene (C{sub 22}H{sub 14}), a five-ring PAH molecule. We report three IR active modes of cationic pentacene at 53.3, 84.8, and 266 {mu}m that may be detectable by space missions such as the SAFARI instrument on board SPICA. In the experiment, pentacene is vaporized from a laser desorption source and cooled by a supersonic argon beam. We have obtained results from two-color resonantly enhanced multiphoton ionization and two-color zero kinetic energy photoelectron (ZEKE) spectroscopy. Several skeletal vibrational modes of the first electronically excited state of the neutral species and those of the cation are assigned, with the aid of ab initio and density functional calculations. Although ZEKE is governed by the Franck-Condon principle different from direct IR absorption or emission, vibronic coupling in the long ribbon-like molecule results in the observation of a few IR active modes. Within the experimental resolution of {approx}7 cm{sup -1}, the frequency values from our calculation agree with the experiment for the cation, but differ for the electronically excited intermediate state. Consequently, modeling of the intensity distribution is difficult and may require explicit inclusion of vibronic interactions.

Zhang Jie; Han Fangyuan; Pei Linsen; Kong Wei [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Li Aigen, E-mail: Wei.Kong@oregonstate.ed [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)

2010-05-20

418

Recoil frame photoemission in multiphoton ionization of small polyatomic molecules: photodynamics of NO2 probed by 400 nm fs pulses  

NASA Astrophysics Data System (ADS)

We report a general method for the complete analysis of the recoil frame photoelectron angular distribution (RFPAD) in n-photon dissociative ionization of small polyatomic molecules, resulting from (n - 1) bound-to-bound transitions plus one-photon ionization of a neutral excited state of the target. This method relies on the decomposition of the RFPAD in terms of the R_K^{} ( {\\chi ,\\theta _e } ) recoil frame azimuthal harmonics (RFAHs) which are the components of its Fourier expansion in ?e, where ? and ?e are the polar angles referring to the polarization axis P and the photoelectron momentum k relative to the ion fragment recoil direction, respectively, and ?e is the azimuth of k relative to P. The RFAH expansion method is illustrated by a detailed experimental and theoretical study of one-colour multiphoton dissociative and non-dissociative ionization of the NO2 molecule of C2v symmetry induced by 400 nm fs laser pulses, which involve electronic and nuclear dynamics within the pulse duration of the order of 70 fs. The reaction mechanism proposed to account for five-photon dissociative ionization of NO2 involves the role of [R*(6a1)-1] Rydberg states populated by three-photon absorption, subsequently ionized by a fourth photon into the NO2+ (X1?g+, v1,v2,v3) manifold involving autoionization of [R*(4b2)-1] Rydberg states, and linear versus bent geometry selective dissociation of NO2+ (X1?g+, v1,v2,v3) by a fifth photon. The reported calculations provide a coherent picture of the experimental findings although all features are not yet well reproduced.

Marggi Poullain, S.; Elkharrat, C.; Li, W. B.; Veyrinas, K.; Houver, J. C.; Cornaggia, C.; Rescigno, T. N.; Lucchese, R. R.; Dowek, D.

2014-06-01

419

Examination of diagnostic features in multiphoton microscopy and optical coherence tomography images of ovarian tumorigenesis in a mouse model  

NASA Astrophysics Data System (ADS)

Ovarian cancer is a deadly disease owing to the non-specific symptoms and suspected rapid progression, leading to frequent late stage detection and poor prognosis. Medical imaging methods such as CT, MRI and ultrasound as well as serum testing for cancer markers have had extremely poor performance for early disease detection. Due to the poor performance of available screening methods, and the impracticality and ineffectiveness of taking tissue biopsies from the ovary, women at high risk for developing ovarian cancer are often advised to undergo prophylactic salpingo-oophorectomy. This surgery results in many side effects and is most often unnecessary since only a fraction of high risk women go on to develop ovarian cancer. Better understanding of the early development of ovarian cancer and characterization of morphological changes associated with early disease could lead to the development of an effective screening test for women at high risk. Optical imaging methods including optical coherence tomography (OCT) and multiphoton microscopy (MPM) are excellent tools for studying disease progression owing to the high resolution and depth sectioning capabilities. Further, these techniques are excellent for optical biopsy because they can image in situ non-destructively. In the studies described in this dissertation OCT and MPM are used to identify cellular and tissue morphological changes associated with early tumor development in a mouse model of ovarian cancer. This work is organized into three specific aims. The first aim is to use the images from the MPM phenomenon of second harmonic generation to quantitatively examine the morphological differences in collagen structure in normal mouse ovarian tissue and mouse ovarian tumors. The second aim is to examine the differences in endogenous two-photon excited fluorescence in normal mouse ovarian tissue and mouse ovarian tumors. The third and final aim is to identify changes in ovarian microstructure resulting from early disease development by imaging animals in vivo at three time points during a long-term survival study.

Watson, Jennifer M.

420

Infrared surface polaritons on bismuth  

NASA Astrophysics Data System (ADS)

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.

Khalilzadeh-Rezaie, Farnood; Smith, Christian W.; Nath, Janardan; Nader, Nima; Shahzad, Monas; Cleary, Justin W.; Avrutsky, Ivan; Peale, Robert E.

2015-01-01

421

Photoelectron circular dichroism of bicyclic ketones from multiphoton ionization with femtosecond laser pulses.  

PubMed

Photoelectron circular dichroism (PECD) is a CD effect up to the ten-percent regime and shows contributions from higher-order Legendre polynomials when multiphoton ionization is compared to single-photon ionization. We give a full account of our experimental methodology for measuring the multiphoton PECD and derive quantitative measures that we apply on camphor, fenchone and norcamphor. Different modulations and amplitudes of the contributing Legendre polynomials are observed despite the similarity in chemical structure. In addition, we study PECD for elliptically polarized light employing tomographic reconstruction methods. Intensity studies reveal dissociative ionization as the origin of the observed PECD effect, whereas ionization of the intermediate resonance is dominating the signal. As a perspective, we suggest to make use of our tomographic data as an experimental basis for a complete photoionization experiment and give a prospect of PECD as an analytic tool. PMID:25492564

Lux, Christian; Wollenhaupt, Matthias; Sarpe, Cristian; Baumert, Thomas

2015-01-12

422

Intravital multiphoton microscopy for dissecting cellular dynamics in arthritic inflammation and bone destruction.  

PubMed

Osteoclasts are giant bone-resorbing polykaryons that differentiate from mononuclear macrophage/monocyte-lineage hematopoietic precursors. They play critical roles not only in normal bone homeostasis (remodeling) but also in the pathogenesis of bone-destructive disorders such as osteoporosis and rheumatoid arthritis. However, how the activity of mature osteoclasts is regulated in vivo remains unclear. To answer this question, we recently developed an advanced imaging system to visualize living bone tissues with intravital multiphoton microscopy. Using this system, we succeeded in visualization of mature osteoclasts in living bones. We herein describe the detailed methodology for visualizing bone resorption of mature osteoclasts in living bone marrow and joints using intravital multiphoton microscopy. This approach would be beneficial for studying the cellular dynamics in arthritic inflammation and bone destruction in vivo and would thus be useful for evaluating novel anti-bone-resorptive drugs. PMID:24706269

Kikuta, Junichi; Ishii, Masaru

2014-01-01

423

Label-free identification of intestinal metaplasia in the stomach using multiphoton microscopy  

NASA Astrophysics Data System (ADS)

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.

Wu, G.; Wei, J.; Zheng, Z.; Ye, J.; Zeng, S.

2014-06-01

424

Vibrational noise removal method for the multi-photon interferometer of an optical loop system  

NASA Astrophysics Data System (ADS)

Multi-photon interference effects of the optical loop in a double-?/V system aid coherent photon control, especially all-optical switching between single photons. In the multi-photon interference, phase fluctuations induced by the mechanical vibration of the optical components should be removed to observe the high fidelity of photon controls. We solved this problem by overlapping coupling and probe beams that have opposite phase shifts in the optical loop system to cancel out phase fluctuation induced by mechanical vibration. We used two independent laser sources to generate two pairs of coupling-probe fields that are resonant on a double-? system. The removal of vibrational phase fluctuation was confirmed by comparison with a normal phase-dependent light-switching experiment.

Kim, Bongjune; Kang, Hoonsoo

2015-04-01

425

Random access multiphoton (RAMP) microscopy for investigation of cerebral blood flow regulation mechanisms  

NASA Astrophysics Data System (ADS)

The processes by which blood flow is regulated at the capillary network level in the brain has been a source of continual debate. It is generally accepted that cerebral blood flow regulation occurs primarily at the arteriolar level. It has been recently suggested, however, that the capillary network is likewise under dynamic regulation. The exact mechanisms of capillary regulation remain unknown. Previously, the limiting factor in determining how the cerebrovascular network is regulated has been the speed at which multiphoton images of large (~200?m2) capillary and arteriole systems can be acquired. Conventional laser scanning microscopy systems are temporally limited in two dimensions. We have developed a Random Access Multiphoton (RAMP) microscope, which operates on the principles of Acousto-optic beam scanning and therefore has no moving parts, specifically for the purpose of imaging blood flow virtually simultaneously throughout the capillary network. We demonstrate the ability to survey blood flow simultaneously in 100 capillaries.

Christensen, Daniel J.; Nedergaard, Maiken

2012-03-01

426

Influence of excitation and deexcitation processes on the dynamics of laser-excited argon clusters  

NASA Astrophysics Data System (ADS)

The excitation of atomic clusters by intense infrared laser pulses leads to the creation of highly charged ions and to the emission of energetic photons. These phenomena, which follow from ionization processes occurring in the cluster, depend significantly on the population of ground states and excited states in the laser-produced nanoplasma. This makes it necessary to account for collisional excitation and deexcitation processes. We investigate the interaction of femtosecond laser pulses with argon clusters by means of a nanoplasma model. Considering laser excitation with single and double pulses, we analyze the role of excitation and deexcitation processes in detail and calculate the yield of highly charged ions and of energetic photons in different wavelength regimes.

Moll, M.; Schlanges, M.; Bornath, Th.; Krainov, V. P.

2015-03-01

427

Plasma effects in the collection of charged particles after nonresonant multiphoton ionization  

Microsoft Academic Search

We present in this work a kinetic model which describes the evolution of charged particles produced by high-intensity, ultrashort laser pulses in nonresonant multiphoton ionization (MPI). The numerically predicted waveforms of the ion detector signal are compared to those observed in nonresonant MPI of Xe with 30 psec, 1013 W\\/cm2, 1.064 micrometers laser pulses. The comparison highlights the relevance of

C. Altucci; Riccardo Bruzzese; C. de Lisio; Salvatore Solimeno; R. B. Kay

1993-01-01

428

Multiphoton ionization and third-harmonic generation in atoms and molecules  

SciTech Connect

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.

Miller, J.C.; Compton, R.N.

1982-01-01

429

Resonance-enhanced multiphoton ionization with circularly polarized light: chiral carbonyls.  

PubMed

An introduction to the principle and possibilities of the new method of circular dichroism laser mass spectrometry is given and its state of development is reviewed. This method allows enantiosensitive, mass-selective probing of chiral molecules. It is based on the combination of resonance-enhanced multiphoton ionization with circularly polarized light and specially modified time-of-flight mass spectrometry. As an example, application to carbonyls is presented. PMID:23430178

Boesl, Ulrich; Bornschlegl, Alexander; Logé, Christoph; Titze, Katharina

2013-09-01

430

Towards laser based improved experimental schemes for multiphoton e+ e- pair production from vacuum  

E-print Network

Numerical estimates for pair production from vacuum in the presence of strong electromagnetic fields are derived, for two experimental schemes : the First concerns a laser based X-FEL and the other imitates the E144 experiment. The approximation adopted in this work is that of two level multiphoton on resonance. Utilizing achievable values of laser beam parameters, an enhancedproduction efficiency of up to 10^11 and 10^15 pairs can be obtained, for the two schemes respectively.

I. Ploumistakis; S. D. Moustaizis; I. Tsohantjis

2009-07-15

431

Single and Multi-Photon Events with Missing Energy in $e^+ e^-$ Collisions at LEP  

Microsoft Academic Search

Single- and multi-photon events with missing energy are selected in 619\\/pb of data collected by the L3 detector at LEP at centre-of-mass energies between 189GeV and 209GeV. The cross sections of the process e^+e^- -> nu nu gamma (gamma) are found to be in agreement with the Standard Model expectations, and the number of light neutrino species is determined, including

P Achard; O Adriani; M Aguilar-Benítez; J Alcaraz; G Alemanni; James V Allaby; A Aloisio; M G Alviggi; H Anderhub; V P Andreev; F Anselmo; A Arefev; T Azemoon; T Aziz; P Bagnaia; A Bajo; G Baksay; L Baksay; S V Baldew; S Banerjee; A Barczyk; R Barillère; P Bartalini; M Basile; N Batalova; R Battiston; A Bay; F Becattini; U Becker; F Behner; L Bellucci; R Berbeco; J Berdugo; P Berges; B Bertucci; B L Betev; M Biasini; M Biglietti; A Biland; J J Blaising; S C Blyth; Gerjan J Bobbink; A Böhm; L Boldizsar; B Borgia; S Bottai; D Bourilkov; Maurice Bourquin; S Braccini; J G Branson; F Brochu; J D Burger; W J Burger; X D Cai; M Capell; G Cara Romeo; G Carlino; A M Cartacci; J Casaus; F Cavallari; N Cavallo; C Cecchi; M Cerrada; M Chamizo-Llatas; Y H Chang; M Chemarin; A Chen; G Chen; H F Chen; H S Chen; G Chiefari; Luisa Cifarelli; F Cindolo; I Clare; R Clare; G Coignet; N Colino; S Costantini; B de la Cruz; S Cucciarelli; J A van Dalen; R De Asmundis; P L Déglon; J Debreczeni; A Degré; K Dehmelt; K Deiters; D Della Volpe; E Delmeire; P Denes; F De Notaristefani; A De Salvo; M Diemoz; M Dierckxsens; C Dionisi; M Dittmar; A Doria; M T Dova; D Duchesneau; M Duda; B Echenard; A Eline; A El-Hage; H El-Mamouni; A Engler; F J Eppling; P Extermann; M A Falagán; S Falciano; A Favara; J Fay; O Fedin; M Felcini; T Ferguson; H S Fesefeldt; E Fiandrini; J H Field; F Filthaut; P H Fisher; W Fisher; I Fisk; G Forconi; Klaus Freudenreich; C Furetta; Yu Galaktionov; S N Ganguli; P García-Abia; M Gataullin; S Gentile; S Giagu; Z F Gong; G Grenier; O Grimm; M W Grünewald; M Guida; R van Gulik; V K Gupta; A Gurtu; L J Gutay; D Haas; D Hatzifotiadou; T Hebbeker; A Hervé; J Hirschfelder; H Hofer; M Hohlmann; G Holzner; S R Hou; Y Hu; B N Jin; L W Jones; P de Jong; I Josa-Mutuberria; D Käfer; M Kaur; M N Kienzle-Focacci; J K Kim; Jasper Kirkby; E W Kittel; A Klimentov; A C König; M Kopal; V F Koutsenko; M H Kräber; R W Krämer; A Krüger; A Kunin; P Ladrón de Guevara; I Laktineh; G Landi; M Lebeau; A Lebedev; P Lebrun; P Lecomte; P Lecoq; P Le Coultre; J M Le Goff; R Leiste; M Levtchenko; P M Levchenko; C Li; S Likhoded; C H Lin; W T Lin; Frank L Linde; L Lista; Z A Liu; W Lohmann; E Longo; Y S Lü; C Luci; L Luminari; W Lustermann; Ma Wen Gan; L Malgeri; A Malinin; C Maña; J Mans; J P Martin; F Marzano; K Mazumdar; R R McNeil; S Mele; L Merola; M Meschini; W J Metzger; A Mihul; H Milcent; G Mirabelli; J Mnich; G B Mohanty; G S Muanza; A J M Muijs; B Musicar; M Musy; S Nagy; S Natale; M Napolitano; F Nessi-Tedaldi; H Newman; A Nisati; T Novák; H Nowak; R A Ofierzynski; G Organtini; I Pal; C Palomares; P Paolucci; R Paramatti; G Passaleva; S Patricelli; T Paul; M Pauluzzi; C Paus; Felicitas Pauss; M Pedace; S Pensotti; D Perret-Gallix; B Petersen; D Piccolo; F Pierella; M Pioppi; P A Piroué; E Pistolesi; V Plyaskin; M Pohl; V Pozhidaev; J Pothier; D Prokofev; D O Prokofiev; J Quartieri; G Rahal-Callot; M A Rahaman; P Raics; N Raja; R Ramelli; P G Rancoita; R Ranieri; A V Raspereza; P A Razis; D Ren; M Rescigno; S Reucroft; S Riemann; K Riles; B P Roe; L Romero; A Rosca; C Rosenbleck; S Rosier-Lees; S Roth; J A Rubio; G Ruggiero; H Rykaczewski; A Sakharov; S Saremi; S Sarkar; J Salicio; E Sánchez; C Schäfer; V Shchegelskii; Herwig Franz Schopper; D J Schotanus; C Sciacca; L Servoli; S Shevchenko; N Shivarov; V Shoutko; E Shumilov; A V Shvorob; D Son; C Souga; P Spillantini; M Steuer; D P Stickland; B Stoyanov; A Strässner; K Sudhakar; G G Sultanov; L Z Sun; S Sushkov; H Suter; J D Swain; Z Szillási; X W Tang; P Tarjan; Ludwig Tauscher; L Taylor; B Tellili; D Teyssier; C Timmermans; Samuel C C Ting; S M Ting; S C Tonwar; J Tóth; C Tully; K L Tung; J Ulbricht; E Valente; R T Van de Walle; R Vásquez; V Veszpremi; G Vesztergombi; I Vetlitskii; D Vicinanza; Gert M Viertel; S Villa; M Vivargent; S Vlachos; I Vodopyanov; H Vogel; H Vogt; I Vorobev; A A Vorobyov; M Wadhwa; Q Wang; X L Wang; Z M Wang; M Weber; P Wienemann; H Wilkens; S Wynhoff; L Xia; Z Z Xu; J Yamamoto; B Z Yang; C G Yang; H J Yang; M Yang; S C Yeh; A Zalite; Yu Zalite; Z P Zhang; J Zhao; G Y Zhu; R Y Zhu; H L Zhuang; A Zichichi; B Zimmermann; M Zöller

2003-01-01

432

Ultrasensitive absorption detection of protein and DNA microarrays based on nonlinear multiphoton wave-mixing spectroscopy  

Microsoft Academic Search

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

Adrian A. Atherton; William G. Tong

2005-01-01

433

Multiphoton lithography of nanocrystalline platinum and palladium for site-specific catalysis in 3D microenvironments.  

PubMed

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

Zarzar, Lauren D; Swartzentruber, B S; Harper, Jason C; Dunphy, Darren R; Brinker, C Jeffrey; Aizenberg, Joanna; Kaehr, Bryan

2012-03-01

434

Multiphoton Process and Anomalous Potential of Cell Membrane by Laser Radiation  

NASA Technical Reports Server (NTRS)

In this paper, by the use of quantum biology and quantum optics, the laser induced potential variation of cell membrane has been studied. Theoretically, we have found a method of calculating the monophoton and multiphoton processes in the formation of the anomalous potential of cell membrane. In contrast with the experimental results, our numerical result is in the same order. Therefore, we have found the possibility of cancer caused by the laser induced anomalous cell potential.

Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhar, Ping; Dong, Lifang

1996-01-01

435

REMOTE SENSING OF OZONE USING AN INFRARED DIFFERENTIAL ABSORPTION SYSTEM  

EPA Science Inventory

A prototype airborne downlooking infrared differential absorption system using CO2 TEA (transverse excited atmospheric) lasers is described. The system uses two wavelengths and topographic reflection to measure the integrated column concentration of ozone between the laser source...

436

Infrared astronomy  

Microsoft Academic Search

This review paper is a survey of infrared astronomy up to early 1969. The techniques and photometric standards are mentioned briefly, and results cover solar, lunar, and planetary observations. Point sources and extended sources both within and beyond the Galaxy are included, ending with the problem of cosmic background radiation. It is concluded that great progress will be possible when

Ronald F. Webbink; William Q. Jeffers

1969-01-01

437

Infrared Spectroscopy  

NSDL National Science Digital Library

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.

C. P. Sherman Hsu

438

Infrared telescope  

NASA Technical Reports Server (NTRS)

The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

Karr, G. R.; Hendricks, J. B.

1985-01-01

439

Infrared Thermometers  

ERIC Educational Resources Information Center

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…

Schaefers, John

2006-01-01

440

Buffer-gas pressure influence on multiphoton absorption in SF6-N2 mixtures  

NASA Astrophysics Data System (ADS)

In this article the results of pulsed IR photoacoustic spectroscopy measurements of multiphoton absorption and relaxation processes in SF6-N2 mixtures are presented. The total average number of absorbed photons per one absorbing molecule (basic physical quantity which characterized multiphoton processes) during the laser pulse total is used and analyzed with a generalized coupled two-level model. This type of analysis is based on buffer-gas pressure (pbuff) functional behavior of total and calculation of its partial values depending on collisions, coll, and laser fluence, ?, influence. Using different methods of photoacoustic spectroscopy, collisionaly induced rotational and vibrational to translational relaxation process parameters (?rot and ?V-T, respectively) are quantitatively obtained and used to determine partial values of coll, rot, and V-T. It will be shown that a method based on ?total/?p functional dependence on pbuff and laser fluence ? can be used to confirm or predict the existence of some processes during the laser pulse, such as dissociation or strong vibrational to vibrational energy transfer, which can contribute to the total amount of energy absorbed into the investigated sample. This could allow one to apply this method and control laser field-molecule interaction in different gas mixtures, and help one to understand multiphoton absorption processes in detail.

Markushev, D. D.; Terzi?, M.; Jovanovi?-Kurepa, J.

2003-01-01

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