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Sample records for infrared multiphoton dissociation

  1. The infrared multiphoton dissociation of three nitrolkanes

    NASA Astrophysics Data System (ADS)

    Wodtke, A. M.; Hintsa, E. J.; Lee, Y. T.

    1986-01-01

    Infrared multiphoton dissociation in a molecular beam has been studied in order to elucidate the collision free, 'thermal' chemistry and dynamics of nitromethane, nitroethane and 2-nitropropane. The isomerization of CH3NO2 to CH3ONO was observed by detecting the CH3O and NO products from the dissociation of the very internally hot, isomerized nitromethane. A novel application of RRKM theory was used to estimate the barrier height to isomerization at 55.5 kcal/mol. The barrier height determination method was tested and found to give excellent results by applying it to the determintaion of the barrier height to HONO elimination from nitroethane, a value which is well known from activation energy measurements. The method was then applied to the case of HONO elimination from 2-nitropropane and it appears that there is good to believe that the barrier height is 3-5 kcal/mol lower in 2-nitropropane than in nitroethane. The success of this method for determining barrier heights shows how a microscopic molecular beam experiment, using infrared multiphoton dissociation where the concept of temperature has no place, can be quantitatively related to pyrolysis experiments which are conducted under collisional, thermal conditions and measure phenomenological quantities such as activation energies.

  2. Does Infrared Multiphoton Dissociation of Vinyl Chloride Yield Cold Vinylidene?

    PubMed

    Fernando, Ravin; Qu, Chen; Bowman, Joel M; Field, Robert W; Suits, Arthur G

    2015-07-01

    Velocity map imaging of the infrared multiphoton dissociation of vinyl chloride shows the formation of HCl in rotational levels below J = 10 that are associated with the three-center elimination pathway. The total translational energy release is observed to peak at 3-5 kcal/mol, which is consistent with the low reverse barrier predicted for the formation of HCl with vinylidene coproducts. Direct dynamics trajectory studies from the three-center transition state reproduce the observed distributions and show that the associated vinylidene is formed with only modest rotational excitation, precluding Coriolis-induced mixing among the excited vibrational levels of acetylene that would lead to distribution of vinylidene character into many vibrationally mixed acetylene vibrational levels. The results suggest that infrared multiphoton dissociation of vinyl chloride is an efficient route to synthesis of stable, cold vinylidene. PMID:26266719

  3. Energetics from Slow Infrared Multiphoton Dissociation of Biomolecules

    PubMed Central

    Jockusch, Rebecca A.; Paech, Kolja

    2005-01-01

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

  4. Imaging NO elimination in the infrared multiphoton dissociation of nitroalkanes and alkyl nitrites

    NASA Astrophysics Data System (ADS)

    Fernando, Ravin; Ariyasingha, Nuwandi M.; Suits, Arthur G.

    2016-02-01

    We present a DC slice imaging study of the decomposition of C2, C3 and C4 nitroalkanes and alkyl nitrites, focusing on the NO elimination channel, possibly a minor pathway. Infrared multiphoton dissociation (IRMPD) is used to induce dissociation on the ground electronic state under collisionless conditions. The channels that produced NO as a product were studied and compared among the target molecules to gain a better understanding of the isomerization of the nitroalkanes prior to dissociation. Trends in the total translational energy and NO rotational temperatures obtained from the images are discussed.

  5. Combined Infrared Multiphoton Dissociation with Ultraviolet Photodissociation for Ubiquitin Characterization

    NASA Astrophysics Data System (ADS)

    Halim, Mohammad A.; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

    2016-06-01

    Herein we report the successful implementation of the consecutive and simultaneous photodissociation with high (213 nm) and low (10.6 μm) energy photons (HiLoPD, high-low photodissociation) on ubiquitin in a quadrupole-Orbitrap mass spectrometer. Absorption of high-energy UV photon is dispersed over the whole protein and stimulates extensive C-Cα backbone fragmentation, whereas low-energy IR photon gradually increases the internal energy and thus preferentially dissociates the most labile amide (C-N) bonds. We noticed that simultaneous irradiation of UV and IR lasers on intact ubiquitin in a single MS/MS experiment provides a rich and well-balanced fragmentation array of a/x, b/y, and z ions. Moreover, secondary fragmentation from a/x and z ions leads to the formation of satellite side-chain ions (d, v, and w) and can help to distinguish isomeric residues in a protein. Implementation of high-low photodissociation in a high-resolution mass spectrometer may offer considerable benefits to promote a comprehensive portrait of protein characterization.

  6. Combined Infrared Multiphoton Dissociation with Ultraviolet Photodissociation for Ubiquitin Characterization.

    PubMed

    Halim, Mohammad A; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

    2016-09-01

    Herein we report the successful implementation of the consecutive and simultaneous photodissociation with high (213 nm) and low (10.6 μm) energy photons (HiLoPD, high-low photodissociation) on ubiquitin in a quadrupole-Orbitrap mass spectrometer. Absorption of high-energy UV photon is dispersed over the whole protein and stimulates extensive C-Cα backbone fragmentation, whereas low-energy IR photon gradually increases the internal energy and thus preferentially dissociates the most labile amide (C-N) bonds. We noticed that simultaneous irradiation of UV and IR lasers on intact ubiquitin in a single MS/MS experiment provides a rich and well-balanced fragmentation array of a/x, b/y, and z ions. Moreover, secondary fragmentation from a/x and z ions leads to the formation of satellite side-chain ions (d, v, and w) and can help to distinguish isomeric residues in a protein. Implementation of high-low photodissociation in a high-resolution mass spectrometer may offer considerable benefits to promote a comprehensive portrait of protein characterization. Graphical Abstract ᅟ. PMID:27287047

  7. Combined Infrared Multiphoton Dissociation with Ultraviolet Photodissociation for Ubiquitin Characterization

    NASA Astrophysics Data System (ADS)

    Halim, Mohammad A.; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

    2016-09-01

    Herein we report the successful implementation of the consecutive and simultaneous photodissociation with high (213 nm) and low (10.6 μm) energy photons (HiLoPD, high-low photodissociation) on ubiquitin in a quadrupole-Orbitrap mass spectrometer. Absorption of high-energy UV photon is dispersed over the whole protein and stimulates extensive C-Cα backbone fragmentation, whereas low-energy IR photon gradually increases the internal energy and thus preferentially dissociates the most labile amide (C-N) bonds. We noticed that simultaneous irradiation of UV and IR lasers on intact ubiquitin in a single MS/MS experiment provides a rich and well-balanced fragmentation array of a/x, b/y, and z ions. Moreover, secondary fragmentation from a/x and z ions leads to the formation of satellite side-chain ions (d, v, and w) and can help to distinguish isomeric residues in a protein. Implementation of high-low photodissociation in a high-resolution mass spectrometer may offer considerable benefits to promote a comprehensive portrait of protein characterization.

  8. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Shaffer, Christopher J.; Martens, Jonathan; Marek, Aleš; Oomens, Jos; Tureček, František

    2016-04-01

    We report a combined experimental and computational study aimed at elucidating the structure of N-terminal fragment ions of the c type produced by electron transfer dissociation of photo-leucine (L*) peptide ions GL*GGKX. The c 4 ion from GL*GGK is found to retain an intact diazirine ring that undergoes selective photodissociation at 355 nm, followed by backbone cleavage. Infrared multiphoton dissociation action spectra point to the absence in the c 4 ion of a diazoalkane group that could be produced by thermal isomerization of vibrationally hot ions. The c 4 ion from ETD of GL*GGK is assigned an amide structure by a close match of the IRMPD action spectrum and calculated IR absorption. The energetics and kinetics of c 4 ion dissociations are discussed.

  9. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study.

    PubMed

    Shaffer, Christopher J; Martens, Jonathan; Marek, Aleš; Oomens, Jos; Tureček, František

    2016-07-01

    We report a combined experimental and computational study aimed at elucidating the structure of N-terminal fragment ions of the c type produced by electron transfer dissociation of photo-leucine (L*) peptide ions GL*GGKX. The c 4 ion from GL*GGK is found to retain an intact diazirine ring that undergoes selective photodissociation at 355 nm, followed by backbone cleavage. Infrared multiphoton dissociation action spectra point to the absence in the c 4 ion of a diazoalkane group that could be produced by thermal isomerization of vibrationally hot ions. The c 4 ion from ETD of GL*GGK is assigned an amide structure by a close match of the IRMPD action spectrum and calculated IR absorption. The energetics and kinetics of c 4 ion dissociations are discussed. Graphical Abstract ᅟ. PMID:27059977

  10. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Shaffer, Christopher J.; Martens, Jonathan; Marek, Aleš; Oomens, Jos; Tureček, František

    2016-07-01

    We report a combined experimental and computational study aimed at elucidating the structure of N-terminal fragment ions of the c type produced by electron transfer dissociation of photo-leucine (L*) peptide ions GL*GGKX. The c 4 ion from GL*GGK is found to retain an intact diazirine ring that undergoes selective photodissociation at 355 nm, followed by backbone cleavage. Infrared multiphoton dissociation action spectra point to the absence in the c 4 ion of a diazoalkane group that could be produced by thermal isomerization of vibrationally hot ions. The c 4 ion from ETD of GL*GGK is assigned an amide structure by a close match of the IRMPD action spectrum and calculated IR absorption. The energetics and kinetics of c 4 ion dissociations are discussed.

  11. Infrared multiphoton dissociation of unsubstituted metal carbonyls at 5 μm

    NASA Astrophysics Data System (ADS)

    Au, Mei-Kuen; Hackett, P. A.; Humphries, M.; John, P.

    1984-01-01

    A frequency-doubled carbon dioxide laser of modest output energy (1 mJ) has been used to study, for the first time, the infrared multiphoton absorption by, and dissociation of, the unsubstituted carbonyls of vanadium, chromium, iron, nickel, molybdenum, and tungsten. The multiphoton absorption cross-sections measured for Ni(CO)4, Fe(CO)5, Cr(CO)6, Mo(CO)6, and V(CO)6 are high (σ˜2×10-17) and ensure facile multiphoton dissociation. In focussed beams a pressure independent reaction yield proportional to the 1.5 power of the beam energy is observed for Fe(CO)5, Cr(CO)6, and Mo(CO)6 implying threshold fluences of only 32, 25, and 26 mJ cm-2, respectively. The stoichiometry of the reaction, observed by a pressure measurement technique, is consistent with production of metal atoms and carbon monoxide as final products for Ni(CO)4, Fe(CO)5, Cr(CO)6, and Mo(CO)6. This extensive decarbonylation along the ground state surface is consistent with recent studies of the photochemistry of these molecules from excited electronic states.

  12. Ab initio molecular dynamics of protonated dialanine and comparison to infrared multiphoton dissociation experiments.

    PubMed

    Marinica, D C; Grégoire, G; Desfrançois, C; Schermann, J P; Borgis, D; Gaigeot, M P

    2006-07-20

    Finite temperature Car-Parrinello molecular dynamics simulations are performed for the protonated dialanine peptide in vacuo, in relation to infrared multiphoton dissociation experiments. The simulations emphasize the flexibility of the different torsional angles at room temperature and the dynamical exchange between different conformers which were previously identified as stable at 0 K. A proton transfer occurring spontaneously at the N-terminal side is also observed and characterized. The theoretical infrared absorption spectrum is computed from the dipole time correlation function, and, in contrast to traditional static electronic structure calculations, it accounts directly for anharmonic and finite temperature effects. The comparison to the experimental infrared multiphoton dissociation spectrum turns out very good in terms of both band positions and band shapes. It does help the identification of a predominant conformer and the attribution of the different bands. The synergy shown between the experimental and theoretical approaches opens the door to the study of the vibrational properties of complex and floppy biomolecules in the gas phase at finite temperature. PMID:16836443

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

    SciTech Connect

    Dai, H.L.

    1981-04-01

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

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

    PubMed Central

    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

    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

  15. Infrared Multiphoton Dissociation of Duplex DNA/Drug Complexes in a Quadrupole Ion Trap

    PubMed Central

    Wilson, Jeffrey J.; Brodbelt, Jennifer S.

    2008-01-01

    Non-covalent duplex DNA/drug complexes formed between one of three 14-base pair non-self complementary duplexes with variable GC content and one of eight different DNA-interactive drugs are characterized by infrared multiphoton dissociation (IRMPD), and the resulting spectra are compared to conventional collisional activated dissociation (CAD) mass spectra in a quadrupole ion trap mass spectrometer. IRMPD yielded comparable information to previously reported CAD results in which strand separation pathways dominate for complexes containing the more AT-rich sequences and/or minor groove binding drugs, whereas drug ejection pathways are prominent for complexes containing intercalating drugs and/or duplexes with higher GC base content. The large photoabsorptive cross-section of the phosphate backbone at 10.6 μm promotes highly efficient dissociation within short irradiation times (< 2 ms at 50 W) or using lower laser powers and longer irradiation times (< 15 W at 15 ms), activation times on par with or shorter than standard CAD experiments. This large photoabsorptivity leads to a controllable ion activation method which can be used to produce qualitatively similar spectra to CAD while minimizing uninformative base loss dissociation pathways or instead be tuned to yield a high degree of secondary fragmentation. Additionally, the low mass cut-off associated with conventional CAD plays no role in IRMPD, resulting in richer MS/MS information in the low m/z region. IRMPD is also used for multi-adduct dissociation in order to increase MS/MS sensitivity, and a two stage IRMPD/IRMPD method is demonstrated as a means to give specific DNA sequence information that would be useful when screening drug binding by mixtures of duplexes. PMID:17249688

  16. Aromatic C-H bond activation revealed by infrared multiphoton dissociation spectroscopy.

    PubMed

    Jašíková, Lucie; Hanikýřová, Eva; Schröder, Detlef; Roithová, Jana

    2012-04-01

    Metal-oxide cations are models of catalyst mediating the C-H bond activation of organic substrates. One of the most powerful reagents suggested in the gas phase is based on CuO(+) . Here, we describe the activation of the aromatic C-H bonds of phenanthroline in its complex with CuO(+) . The reaction sequence starts with a hydrogen atom abstraction by the oxygen atom from the 2-position of the phenanthroline ring, followed by OH migration to the ring. Using infrared multiphoton spectroscopy, it is shown that the reaction can be energetically facilitated by additional coordination of a water ligand to the copper ion. As the reaction is intramolecular, a spectroscopic characterization of the product is mandatory in order to unambiguously address the reaction mechanism. PMID:22689621

  17. Combined infrared multiphoton dissociation and electron-capture dissociation using co-linear and overlapping beams in Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Mihalca, Romulus; van der Burgt, Yuri E M; McDonnell, Liam A; Duursma, Marc; Cerjak, Iliya; Heck, Albert J R; Heeren, Ron M A

    2006-01-01

    A novel set-up for Fourier transform ion cyclotron resonance mass spectrometry (FTICR) is reported for simultaneous infrared multiphoton dissociation (IRMPD) and electron-capture dissociation (ECD). An unmodified electron gun ensures complete, on-axis overlap between the electron and the photon beams. The instrumentation, design and implementation of this novel approach are described. In this configuration the IR beam is directed into the ICR cell using a pneumatically actuated mirror inserted into the ion-optical path. Concept validation was made using different combinations of IRMPD and ECD irradiation events on two standard peptides. The ability to perform efficient IRMPD, ECD and especially simultaneous IRMPD and ECD using lower irradiation times is demonstrated. The increase in primary sequence coverage, with the combined IRMPD and ECD set-up, also increases the confidence in peptide and protein assignments. PMID:16705647

  18. Application of Infrared Multiphoton Dissociation Spectroscopy for the Study of Chiral Recognition in the Protonated Serine Clusters: Part II

    NASA Astrophysics Data System (ADS)

    Sunahori, Fumie X.; Kitova, Elena N.; Klassen, John S.; Xu, Yunjie; Yang, Guochun

    2011-06-01

    Serine is an amino acid which has long been known to form the magic-number serine octamer [Ser_8 + H]^+. It has been shown that the serine octamer exhibits strong preference for homochirality. Although a few possible structures for the homochiral serine octamer have been proposed, no definite conclusion has so far been drawn. Last year at this conference, we reported on the study of the protonated serine octamer and dimer as well as the chiral recognition in these clusters using infrared multiphoton dissociation (IRMPD) spectroscopic technique coupled with a Fourier transform ion cyclotron (FTICR) mass spectrometer. Here we present our latest results on the search for the infrared signatures of chiral recognition in the serine octamer and the dimer using a mixture of the deuterated 2,3,3-d_3-L-serine and normal D-serine solution. Using the isotopic labeled species, we could isolate the heterochiral species and obtain their IRMPD spectra which can be directly compared with those of the homochiral species. As an aid to interpret the observed spectra, molecular structures and vibrational frequencies of both homochiral and heterochiral octamer and dimer have been predicted by ab initio calculations. New insights into the hitherto undetermined structure of the serine octamer will be discussed. S. C. Nanita and R. G. Cooks Angew. Chem. Int. Ed. 45, (554), 2006.

  19. Photodissociation dynamics of nitromethane and methyl nitrite by infrared multiphoton dissociation imaging with quasiclassical trajectory calculations: Signatures of the roaming pathway

    NASA Astrophysics Data System (ADS)

    Dey, Arghya; Fernando, Ravin; Abeysekera, Chamara; Homayoon, Zahra; Bowman, Joel M.; Suits, Arthur G.

    2014-02-01

    We combine the techniques of infrared multiphoton dissociation (IRMPD) with state selective ion imaging to probe roaming dynamics in the unimolecular dissociation of nitromethane and methyl nitrite. Recent theoretical calculations suggest a "roaming-mediated isomerization" pathway of nitromethane to methyl nitrite prior to decomposition. State-resolved imaging of the NO product coupled with infrared multiphoton dissociation was carried out to examine this unimolecular decomposition near threshold. The IRMPD images for the NO product from nitromethane are consistent with the earlier IRMPD studies that first suggested the importance of an isomerization pathway. A significant Λ-doublet propensity is seen in nitromethane IRMPD but not methyl nitrite. The experimental observations are augmented by quasiclassical trajectory calculations for nitromethane and methyl nitrite near threshold for each dissociation pathway. The observation of distinct methoxy vibrational excitation for trajectories from nitromethane and methyl nitrite dissociation at the same total energy show that the nitromethane dissociation bears a nonstatistical signature of the roaming isomerization pathway, and this is possibly responsible for the nitromethane Λ-doublet propensity as well.

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

    PubMed Central

    Xu, Zhe; Brodbelt, Jennifer S.

    2013-01-01

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

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

    PubMed

    Tsybin, Youri O; Witt, Matthias; Baykut, Gökhan; Kjeldsen, Frank; Håkansson, Per

    2003-01-01

    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 spectrometer. This new hardware design allows high-rate electron capture dissociation (ECD) to be carried out by a hollow electron beam coaxial with the ion cyclotron resonance (ICR) trap. Infrared multiphoton dissociation (IRMPD) can also be performed with an on-axis IR-laser beam passing through a hole at the centre of the dispenser cathode. Electron and photon irradiation times of the order of 100 ms are required for efficient ECD and IRMPD, respectively. As ECD and IRMPD generate fragments of different types (mostly c, z and b, y, respectively), complementary structural information that improves the characterization of peptides and proteins by FTICR mass spectrometry can be obtained. The developed technique enables the consecutive or simultaneous use of the ECD and IRMPD methods within a single FTICR experimental sequence and on the same ensemble of trapped ions in multistage tandem (MS/MS/MS or MS(n)) mass spectrometry. Flexible changing between ECD and IRMPD should present advantages for the analysis of protein digests separated by liquid chromatography prior to FTICRMS. Furthermore, ion activation by either electron or laser irradiation prior to, as well as after, dissociation by IRMPD or ECD increases the efficiency of ion fragmentation, including the w-type fragment ion formation, and improves sequencing of peptides with multiple disulfide bridges. The developed instrumental configuration is essential for combined ECD and IRMPD on FTICR mass spectrometers with limited access into the ICR trap. PMID:12872281

  2. Combined electron capture and infrared multiphoton dissociation for multistage MS/MS in a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Håkansson, Kristina; Chalmers, Michael J; Quinn, John P; McFarland, Melinda A; Hendrickson, Christopher L; Marshall, Alan G

    2003-07-01

    We have mounted a permanent on-axis dispenser cathode electron source inside the magnet bore of a 9.4-T Fourier transform ion cyclotron resonance mass spectrometer. This configuration allows electron capture dissociation (ECD) to be performed reliably on a millisecond time scale. We have also implemented an off-axis laser geometry that enables simultaneous access to ECD and infrared multiphoton dissociation (IRMPD). Optimum performance of both fragmentation techniques is maintained. The analytical utility of performing either ECD or IRMPD on a given precursor ion population is demonstrated by structural characterization of several posttranslationally modified peptides: IRMPD of phosphorylated peptides results in few backbone (b- and y-type) cleavages, and product ion spectra are dominated by neutral loss of H3PO4. In contrast, ECD provides significantly more backbone (c- and z*-type) cleavages without loss of H3PO4. For N-glycosylated tryptic peptides, IRMPD causes extensive cleavage of the glycosidic bonds, providing structural information about the glycans. ECD cleaves all backbone bonds (except the N-terminal side of proline) in a 3-kDa glycopeptide with no saccharide loss. However, only a charge-reduced radical species and some side chain losses are observed following ECD of a 5-kDa glycopeptide from the same protein. An MS3 experiment involving IR laser irradiation of the charge-reduced species formed by electron capture results in extensive dissociation into c- and z-type fragment ions. Mass-selective external ion accumulation is essential for the structural characterization of these low-abundance (modified) peptides. PMID:12964777

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

    PubMed

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

    2015-01-01

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

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

    SciTech Connect

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

    2007-10-14

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

  5. H{sub 2} EJECTION FROM POLYCYCLIC AROMATIC HYDROCARBONS: INFRARED MULTIPHOTON DISSOCIATION STUDY OF PROTONATED ACENAPHTHENE AND 9,10-DIHYDROPHENANTHRENE

    SciTech Connect

    Szczepanski, Jan; Vala, Martin T.; Oomens, Jos; Steill, Jeffrey D.

    2011-01-20

    The infrared multiple-photon dissociation (IRMPD) spectra of protonated acenaphthene ([ACN+H]{sup +}) and 9,10-dihydrophenanthrene ([DHP+H]{sup +}) have been recorded using an infrared free electron laser after the compounds were protonated by electrospray ionization and trapped in a Fourier transform ion cyclotron mass spectrometer. In both compounds, the loss of two mass units is predominant. Density functional calculations (B3LYP/6-311++G(d,p)) of the infrared spectra of all possible protonated isomers of each species showed that the observed IRMPD spectra are best fit to the isomer with the largest proton affinity and lowest relative electronic energy. Potential energy surfaces of the most stable isomers of [ACN+H]{sup +} and [DHP+H]{sup +} have been calculated for H and H{sub 2} loss. The lowest energy barriers are for loss of H{sub 2}, with predicted energies 4.28 and 4.15 eV, respectively. After H{sub 2} ejection, the adjacent aliphatic hydrogens migrate to the bare ejection site and stabilize the remaining fragment. Single H loss may occur from [ACN+H]{sup +} but the energy required is higher. No single H loss is predicted from [DHP+H]{sup +}, only H migration around the carbon skeleton. The vibrational bands in the parent closed-shell protonated polycyclic aromatic hydrocarbons are compared to bands observed from the interstellar medium.

  6. Multiphoton dissociation of electrosprayed megadalton-sized DNA ions in a charge-detection mass spectrometer.

    PubMed

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

    2015-01-01

    Charge detection mass spectrometry in combination with a linear electrostatic ion trap coupled to a continuous wavelength infrared CO2 laser has been used to study the multiphoton dissociation of DNA macromolecular ions. Samples, with masses ranging from 2.23 to 31.5 MDa, include single strand circular M13mp18, double strand circular M13mp18, and double strand linear LambdaPhage DNA fragments. Their activation energies for unimolecular dissociation were determined. Activation energy values slightly increase as a function of the molecular weight. The most important result is the difference between the fragmentations observed for hybridized double-strands and dimers of single strands. PMID:25348472

  7. Multiphoton microscopy with near infrared contrast agents

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  8. 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)

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

    2013-04-01

    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.

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

    SciTech Connect

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

    2015-04-09

    The gas-phase complex UO₂(TMOGA)₂²⁺ (TMOGA = tetramethyl-3-oxa-glutaramide) prepared by electrospray ionization was characterized by infrared multiphoton dissociation (IRMPD) spectroscopy. The IRMPD spectrum from 700–1800 cm⁻¹ was interpreted using a computational study based on density functional theory. The predicted vibrational frequencies are in good agreement with the measured values, with an average deviation of only 8 cm⁻¹ (<1%) and a maximum deviation of 21 cm⁻¹ (<2%). The only IR peak assigned to the linear uranyl moiety was the asymmetric ν₃ mode, which appeared at 965 cm⁻¹ and was predicted by DFT as 953 cm⁻¹. This ν₃ frequency is red-shifted relative to bare uranyl, UO₂²⁺, by ca. 150 cm⁻¹ due to electron donation from the TMOGA ligands. Based on the degree of red-shifting, it is inferred that two TMOGA oxygen-donor ligands have a greater effective gas basicity than the four monodentate acetone ligands in UO₂(acetone)₄²⁺. The uranyl ν₃ frequency was also computed for uranyl coordinated by two TMGA ligands, in which the central Oether of TMOGA has been replaced by CH₂. The computed ν₃ for UO₂(TMGA)₂²⁺, 950 cm⁻¹, is essentially the same as that for UO₂(TMOGA)₂²⁺, suggesting that electron donation to uranyl from the Oether of TMOGA is minor. The computed ν₃ asymmetric stretching frequencies for the three actinyl complexes, UO₂(TMOGA)₂²⁺, NpO₂(TMOGA)₂²⁺ and PuO₂(TMOGA)₂²⁺, are comparable. This similarity is discussed in the context of the relationship between ν₃ and intrinsic actinide-oxygen bond energies in actinyl complexes.

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

    PubMed

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

    2012-09-01

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

  11. Infrared multiphoton dissociation spectroscopy of a gas-phase complex of uranyl and 3-oxa-glutaramide: an extreme red-shift of the [O═U═O](2+) asymmetric stretch.

    PubMed

    Gibson, John K; Hu, Han-Shi; Van Stipdonk, Michael J; Berden, Giel; Oomens, Jos; Li, Jun

    2015-04-01

    The gas-phase complex UO2(TMOGA)2(2+) (TMOGA = tetramethyl-3-oxa-glutaramide) prepared by electrospray ionization was characterized by infrared multiphoton dissociation (IRMPD) spectroscopy. The IRMPD spectrum from 700-1800 cm(-1) was interpreted using a computational study based on density functional theory. The predicted vibrational frequencies are in good agreement with the measured values, with an average deviation of only 8 cm(-1) (<1%) and a maximum deviation of 21 cm(-1) (<2%). The only IR peak assigned to the linear uranyl moiety was the asymmetric ν3 mode, which appeared at 965 cm(-1) and was predicted by DFT as 953 cm(-1). This ν3 frequency is red-shifted relative to bare uranyl, UO2(2+), by ca. 150 cm(-1) due to electron donation from the TMOGA ligands. Based on the degree of red-shifting, it is inferred that two TMOGA oxygen-donor ligands have a greater effective gas basicity than the four monodentate acetone ligands in UO2(acetone)4(2+). The uranyl ν3 frequency was also computed for uranyl coordinated by two TMGA ligands, in which the central Oether of TMOGA has been replaced by CH2. The computed ν3 for UO2(TMGA)2(2+), 950 cm(-1), is essentially the same as that for UO2(TMOGA)2(2+), suggesting that electron donation to uranyl from the Oether of TMOGA is minor. The computed ν3 asymmetric stretching frequencies for the three actinyl complexes, UO2(TMOGA)2(2+), NpO2(TMOGA)2(2+) and PuO2(TMOGA)2(2+), are comparable. This similarity is discussed in the context of the relationship between ν3 and intrinsic actinide-oxygen bond energies in actinyl complexes. PMID:25785482

  12. Controllable infrared continuum source for multiphoton imaging

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    We report on multiphoton imaging of biological samples performed with continuum infrared source generated in photonic crystal fibers (PCFs). We studied the spectra generated in PCFs with dispersion profiles designed to maximize the power density in the 700-1000 nm region, where the two-photon absorption cross sections of the most common dyes lie. Pumping in normal dispersion region, with <140 femtosecond pulses delivered by a tunable Ti:Sa laser (Chameleon Ultra II by Coherent Inc.), results in a limitation of nonlinear broadening up to a mean power density above 2 mW/nm. Axial and lateral resolution obtained with a scanning multiphoton system has been measureed to be near the theoretical limit. The possibility of simultaneous two-photon excitation of different dyes in the same sample and high image resolution are demonstrated at tens of microns in depth. Signal-to-noise ratio and general performances are found to be comparable with those of a single wavelength system, used for comparison.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2013-07-12

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

  15. Infrared multiphoton resummation in quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Mati, P.

    2016-02-01

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

  16. Single- and multiphoton infrared laser spectroscopy of atomic negative ions

    NASA Astrophysics Data System (ADS)

    Scheer, Michael

    A pulsed, tunable infrared laser source (0.6-5.2 μm) has been developed on the basis of a commercial dye laser and non-linear optical conversion techniques. This laser source was combined with a keV negative ion beam apparatus in a crossed-beam geometry, with the aim to systematically study several atomic negative ions through a variety of single- and multiphoton detachment experiments. Photodetachment threshold spectra of 21 ionic species (B- , C-, O-, Al- , Si-, Cr-, Co- , Ni-, Cu-, Ge- , Mo-, Rh-, Pd- , Ag-, Sn-, Sb- , Te-, Cs-, Ir- , Pt-, and Bi-) have been recorded, in most cases resulting in very accurate determinations of ionic binding energies, marking substantial improvements over previous experimental values. In fact, several ionic states investigated here had not been observed previously. Different schemes for resonant multiphoton detachment of atomic negative ions were demonstrated for the first time. These studies were conducted with several anions (Si-, Sri- , Sb-, Te-, Ir- , and Pt-) providing highly accurate ionic energy level splittings and clearly demonstrating that multiphoton probes are generally applicable to negative ion structure.

  17. Multiphoton ionisation and dissociation of NO 2 by 50 fs laser pulses

    NASA Astrophysics Data System (ADS)

    Singhal, R. P.; Kilic, H. S.; Ledingham, K. W. D.; Kosmidis, C.; McCanny, T.; Langley, A. J.; Shaikh, W.

    1996-04-01

    Multiphoton ionisation and dissociation of NO 2 has been studied experimentally at 375 nm for laser pulse widths of 10 ns and 50 fs. The parent NO 2 ion peak is not seen in the ns data. In all spectra, the main peak observed is due to the ionisation of the NO molecule which results from the dissociation of excited NO 2 formed after absorbing a 375 nm photon. The intensity dependencies of both NO and NO 2 ion peaks have also been measured. The data has been analysed within the context of a rate equation model using published cross-sections and dissociation rates except for the two-photon ionisation cross-section for NO 2 which was chosen to reproduce the NO 2/NO ion signal ratios at 50 fs. The rate equation model provides a good description of the complete set of data. Indirectly, it may be concluded that coherence effects do not play an important role in the multiphoton excitation/ionisation of NO 2. The data also rules out the importance of above-ionisation dissociation in NO 2 — a conclusion which is consistent with previous data at 496 and 248 nm for laser pulse widths ⩾ 300 fs.

  18. Vibrationally resolved electron-nuclear energy sharing in above-threshold multiphoton dissociation of CO

    NASA Astrophysics Data System (ADS)

    Sun, Xufei; Li, Min; Shao, Yun; Liu, Ming-Ming; Xie, Xiguo; Deng, Yongkai; Wu, Chengyin; Gong, Qihuang; Liu, Yunquan

    2016-07-01

    We study the photon energy sharing between the photoelectron and the nuclei in the process of above-threshold multiphoton dissociative ionization of CO molecules by measuring the joint energy spectra. The experimental observation shows that the electron-nuclear energy sharing strongly depends on the vibrational state. The experimental observation shows that both the energy deposited to the nuclei of C O+ and the emitted photoelectron decrease with increasing the vibrational level. Through studying the vibrationally resolved nuclear kinetic energy release and photoelectron energy spectra at different laser intensities, for each vibrational level of C O+ , the nuclei always tend to take the same amount of energy in every vibrational level regardless of the laser intensity, while the energy deposited to the photoelectron varies with respect to the laser intensity because of the ponderomotive shifted energy and the distinct dissociative ionization mechanisms.

  19. Buffer-gas influence on multiphoton absorption and dissociation in different gas mixtures

    NASA Astrophysics Data System (ADS)

    Nikolić, J. D.; Rabasović, M. D.; Markushev, D. D.; Jovanović-Kurepa, J.

    2008-03-01

    Buffer-gas influence on the multiphoton absorption and dissociation in different mixtures was investigated using the simple method based on the empirical and theoretical vibrational energy distribution, generalized coupled two-level model and photoacoustic cell especially designed for low pressures studies. Energy transfer efficiency was analyzed by means of pulsed photoacoustic spectroscopy technique. Collisional effects of buffer-gas (Ar) pressure are introduced to enhance the absorption and relaxation characteristics of irradiated absorbing molecules (SF 6). Functional behavior of mean number of absorbed photons per molecule < n> total and a dependence on buffer-gas pressure ( pbuff) which enables us to confirm or predict some physical and chemical processes are presented. Limitation of proposed model was analyzed depending on both gas pressure and laser fluence. Results are compared with other previously obtained by the same experimental technique but for different absorber and different molecular buffer-gas.

  20. The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

    PubMed Central

    Poveda, Juan Carlos; Román, Alejandro San; Guerrero, Alfonso; Álvarez, Ignacio; Cisneros, Carmen

    2008-01-01

    The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ∼1010 W cm−2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CHm+ (m = 2, 4), C2H4+ and C5H4+2 ions. CH5+ and CH6+ were observed which have not been reported before in photodissociation tetracene experiments. PMID:19325732

  1. Single and Multiphoton Infrared Laser Sectroscopy of Atomic Negative Ions

    NASA Astrophysics Data System (ADS)

    Bilodeau, René C.; Scheer, Michael; Brodie, Cicely A.; Haugen, Harold K.

    1998-05-01

    We have investigated several atomic negative ion species with the aid of a pulsed, tunable infrared laser source (M. Scheer, H.K. Haugen, and D.R. Beck, Phys. Rev. Lett. 79), 4104 (1997); M. Scheer et al, Phys. Rev. Lett. 80, 684 (1998).. In a comprehensive study of the carbon group negative ions (C^-, Si^-, Ge^-, Sn^-, Pb^-) a combination of single and multiphoton techniques was utilized to determine the bound terms and fine structure levels of the p^3 (ground state) configuration. The results comprise accurate electron affinities and the first experimental data on the fine structure of the ^2DJ terms in Si^-, Ge^-, and Sn^-. In addition, photodetachment threshold spectroscopy provided significantly impoved electron affinities for B, Cr, Mo, Ru, Rh, W, and Bi. The detachment cross section of B^-(^3P_J) appeared as a sequence of closely spaced thresholds which enabled the first experimental determination of the ionic fine structure. The detachment cross section of W^- indicates the presence of unexpected and previously unobserved resonances just below the W(5d^56s ^7S_3) threshold.

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

    PubMed

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

    2011-11-14

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

  3. Selective IR multiphoton dissociation of molecules in a pulsed gas-dynamically cooled molecular flow interacting with a solid surface as an alternative to low-energy methods of molecular laser isotope separation

    NASA Astrophysics Data System (ADS)

    Makarov, G. N.; Petin, A. N.

    2016-03-01

    We report the results of studies on the isotope-selective infrared multiphoton dissociation (IR MFD) of SF6 and CF3I molecules in a pulsed, gas-dynamically cooled molecular flow interacting with a solid surface. The productivity of this method in the conditions of a specific experiment (by the example of SF6 molecules) is evaluated. A number of low-energy methods of molecular laser isotope separation based on the use of infrared lasers for selective excitation of molecules are analysed and their productivity is estimated. The methods are compared with those of selective dissociation of molecules in the flow interacting with a surface. The advantages of this method compared to the low-energy methods of molecular laser isotope separation and the IR MPD method in the unperturbed jets and flows are shown. It is concluded that this method could be a promising alternative to the low-energy methods of molecular laser isotope separation.

  4. Cell damage in near-infrared multimode optical traps as a result of multiphoton absorption

    NASA Astrophysics Data System (ADS)

    König, K.; Liang, H.; Berns, M. W.; Tromberg, B. J.

    1996-07-01

    We report on cell damage of single cells confined in continuous-wave (cw), near-infrared (NIR) multimode optical traps as a result of multiphoton absorption phenomena. Trapping beams at NIR wavelengths less than 800 nm are capable of damaging cells through a two-photon absorption process. Cell damage is more pronounced in multimode cw traps compared with single-frequency true cw NIR traps because of transient power enhancement by longitudinal mode beating. Partial mode locking in tunable cw Ti:sapphire lasers used as trapping beam sources can produce unstable subnanosecond pulses at certain wavelengths that amplify multiphoton absorption effects significantly. We recommend the use of single-frequency long-wavelength NIR trapping beams for optical micromanipulation of vital cells.

  5. Isotope effects and bond softening in intense-laser-field multiphoton dissociation of H[sub 2][sup +

    SciTech Connect

    Miret-Artes, S. ); Atabek, O. )

    1994-02-01

    Isotope effects in the H[sub 2][sup +-]D[sub 2][sup +] fragmentation by intense laser fields offer the possibility of a multiphoton interpretation of the bond-softening mechanism. Surprisingly, the calculations indicate that the one-photon dissociation of D[sub 2][sup +] is favored with respect to that of H[sub 2][sup +]. This cannot be understood, as has previously been done, by a single-photon mechanism following tunneling through a lowered potential barrier, obviously more transparent for the lighter H[sub 2][sup +]. It is rather a competition between this single-photon mechanism and a five-photon mechanism which is suggested for a more realistic interpretation.

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

    NASA Astrophysics Data System (ADS)

    Philis, John G.; Kosmidis, Constantine; Tzallas, Paraskevas

    1998-12-01

    The 2-photon excitation of the 3p and 3d Rydberg states in jet-cooled cyclopentanone has been investigated by resonance enhanced multiphoton ionization (REMPI) in a time of flight mass spectrometer. The three 3px,y,z components are clearly resolved while the case for the 3di excitations is obscure due to the S1 one-photon resonance. The ns laser induced mass spectra are characteristic of hard ionization while the fs laser induced mass spectrum is very similar to the Electron Impact one.

  7. Dynamics of C-Br bond dissociation in methyl 2-bromopropionate at 235 nm: A resonance-enhanced multiphoton ionization study

    NASA Astrophysics Data System (ADS)

    Saha, Ankur; Kumar, Awadhesh; Naik, Prakash D.

    2016-01-01

    The dynamics of the C-Br bond dissociation on UV excitation of methyl 2-bromopropionate mainly to the 1(nσ*) state, repulsive in the C-Br bond, has been investigated, employing resonance-enhanced multiphoton ionization. Both the ground state and spin-orbits excited bromine atoms were detected, with the former being the major channel. Bromine fragments show bimodal translational energy distributions, with slow and fast (major) bromine atoms arising mainly from the ground and excited electronic states, respectively. The measured recoil anisotropy suggests isotropic angular distributions of bromine atoms. Molecular orbital calculations reveal an important role of avoided curve crossing on C-Br bond dissociation dynamics.

  8. Signal flow graph approach to multiphoton analysis and transient characteristics of mode-locked far infrared lasers

    SciTech Connect

    Chung, H.K.

    1981-01-01

    The signal flow graph application to the analysis of multiphoton interactions has been developed in this study. It is shown that the Schroedinger equation for the multiphoton interactions can be represented as signal flow graphs in the semiclassical limit. A few examples are given to illustrate the construction, manipulation and application of the graphs. Also, the generation of temporally short far infrared pulses and their evolution in time and space have been examined experimentally and theoretically. It is shown that the far infrared pulsewidth can be as short as one-half the pump pulsewidth which is already shorter than the molecular relaxation times. In particular, the far infrared pulse energy is found to be scaled in z as e..sqrt..gz, contrary to the Beer's law growth, e/sup gz/.

  9. UV laser multiphoton ionization--dissociation of phenylsilane and its homogeneous dimers

    NASA Astrophysics Data System (ADS)

    Kosmidis, Constantine; Philis, John G.

    1998-01-01

    Homogeneous dimers of phenylsilane, formed in a rare-gas seeded supersonic expansion have been studied by laser resonant two-photon ionization combined with a time-of-flight mass spectrometer. The resonant intermediate states are the S1 (270 nm) and S2 (210 nm) ones. The ionization of phenylsilane monomer is inefficient at 210 nm whereas phenylsilane homo-dimers are resonantly ionized with high efficiency at this wavelength region. The wavelength dependence of the dimer at S1<-- S0 origin region implies the existence of at least two, almost isoenergetic, dimer conformers in the molecular beam. Photoionization of phenylsilane dimer induces chemical reactions within the dimer. The detected dissociation channels have to do with -SiH3 and -C6H6 loss and proton-transfer. Van der Waals fragmentation (evaporation of a neutral phenylsilane) is also taking place.

  10. ARTICLES: Isotope separation by multiphoton dissociation of molecules using high-power CO2 laser radiation. Scaling of the process for carbon isotopes

    NASA Astrophysics Data System (ADS)

    Abdushelishvili, G. I.; Avatkov, O. N.; Bagratashvili, Viktor N.; Baranov, V. Yu; Bakhtadze, A. B.; Velikhov, E. P.; Vetsko, V. M.; Gverdtsiteli, I. G.; Dolzhikov, V. S.; Esadze, G. G.; Kazakov, S. A.; Kolomiĭskiĭ, Yu R.; Letokhov, V. S.; Pigul'skiĭ, S. V.; Pis'mennyĭ, V. D.; Ryabov, Evgenii A.; Tkeshelashvili, G. I.

    1982-04-01

    Data are presented on multiphoton dissociation of halogenated methanes, CF3I and CF3Br, in a pulsed CO2 laser field in the single-pulse irradiation regime. It is shown that the high parameters of an elementary separation event (dissociation yield and selectivity, quantum efficiency) for these molecules can be used to achieve efficient laser separation of the carbon isotopes 12C and 13C. An analysis is made of problems involved in organizing the chemical cycle when the process is scaled up. A description is given of an apparatus for scaled-up laser isotope separation, including a pulse-periodic CO2 laser with a kilowatt average power, and a laser separation cell. Experiments carried out using this apparatus showed that the high parameters obtained in the single-pulse regime can also be achieved using this design and a yield rate comparable with that of traditional separation systems can be achieved for fairly low energy losses. These results make it possible to develop a commercial system for laser isotope separation using multiphoton dissociation of molecules.

  11. Infrared Multiple Photon Dissociation Spectroscopy Of Metal Cluster-Adducts

    NASA Astrophysics Data System (ADS)

    Cox, D. M.; Kaldor, A.; Zakin, M. R.

    1987-01-01

    Recent development of the laser vaporization technique combined with mass-selective detection has made possible new studies of the fundamental chemical and physical properties of unsupported transition metal clusters as a function of the number of constituent atoms. A variety of experimental techniques have been developed in our laboratory to measure ionization threshold energies, magnetic moments, and gas phase reactivity of clusters. However, studies have so far been unable to determine the cluster structure or the chemical state of chemisorbed species on gas phase clusters. The application of infrared multiple photon dissociation IRMPD to obtain the IR absorption properties of metal cluster-adsorbate species in a molecular beam is described here. Specifically using a high power, pulsed CO2 laser as the infrared source, the IRMPD spectrum for methanol chemisorbed on small iron clusters is measured as a function of the number of both iron atoms and methanols in the complex for different methanol isotopes. Both the feasibility and potential utility of IRMPD for characterizing metal cluster-adsorbate interactions are demonstrated. The method is generally applicable to any cluster or cluster-adsorbate system dependent only upon the availability of appropriate high power infrared sources.

  12. Infrared FEL photochemistry: Multiple-photon dissociation of freon gas

    NASA Astrophysics Data System (ADS)

    Newnam, B. E.; Early, J. W.; Lyman, J. L.

    Wavelength tunability, synchrotron sidebands, and picosecond pulse structure are inherent FEL characteristics that should be advantageous for photochemistry involving infrared multiple-photon photodissociation. Tuned to an absorption resonance, the FEL sideband structure will overlap the broad, excited-state spectral absorption and should lead to enhanced dissociation. The Los Alamos APEX FEL was operated with and without sidebands to test this hypothesis on CFCl3 (Freon 11), an inert chlorofluorocarbon widely used in refrigeration systems and one of the gases implicated as depleting the ozone in the Earth's stratospheric layer. The FEL wavelength was set at the C-Cl stretch absorption resonance at 11.8-microns, the oscillator cavity length was detuned first to minimize and then to maximize the spectral bandwidth, and the beam was focused through a pair of test cells (1.0 Torr Freon + 1.7 Torr air). Comparison of final and initial absorbance spectra indicated the CFCl3 photodissociation yield was 1.2% for the cell exposed with sideband spectra (3% FWHM) and 9-ns micropulse separation. Negligible effect was seen without sidebands, albeit at lower total beam fluence. Although the result of this single experiment is not large enough to be conclusive, it does provide a basis for optimizing the FEL temporal and spectral parameters to attain higher photodissociation yield in future tests.

  13. A comparison of the femto-, pico- and nano-second multiphoton ionization and dissociation processes of NO 2 at 248 and 496 nm

    NASA Astrophysics Data System (ADS)

    Ledingham, K. W. D.; Kosmidis, C.; Georgiou, S.; Couris, S.; Singhal, R. P.

    1995-12-01

    The multiphoton ionization and dissociation of NO 2 at 248 nm ( B˜2B 2←X 2A 1) and 496 nm has been carried out for a number of different laser pulsewidths from 15 ns to 300 fs by time-of-flight mass spectrometry in a molecular beam. At 248 nm the NO 2/NO ion ratio (NO 2+/NO +) varies from about 1% using nanosecond laser pulses to about 60% for the shortest pulses used (300 fs). In contrast, at 496 nm the NO 2+/NO + ratio remains very small for excitation with both 5 ps and 500 fs pulses. These results are interpreted in terms of the limited knowledge of the dissociation rates above the NO(X)+O( 1D) fragmentation threshold at 40126 cm -1 using a simple rate equation model. The results can be described using dissociation rates which increase with decreasing pulsewidth, an idea which conforms with the distinction that has been drawn between time and frequency domain experiments. The implications of the results for the analytical potential of femtosecond mass spectrometry are discussed.

  14. Role of high-lying electronic states on the angular distribution of photofragments in multiphoton dissociation of D{sub 2}{sup +} by intense laser fields

    SciTech Connect

    Sen, Sanjay; Dutta, Bibhas; Bhattacharyya, S. S.; Saha, Samir

    2003-05-01

    We have theoretically investigated the role of high lying electronic states 2p{pi}{sub u} and 3d{sigma}{sub g} on multiphoton dissociation of D{sub 2}{sup +} from initial vibrational-rotational levels v{sub i}=4,5 and J{sub i}=0,1 by linearly polarized light with wavelength 400 nm and intensity 3x10{sup 13} W/cm{sup 2}. We have found that for initial level v{sub i}=4 and J{sub i}=1, a considerable number of photofragments is ejected perpendicular to the polarization direction of the laser field. It is shown that the perpendicular dissociation is due to the (net) four-photon absorption of the ground 1s{sigma}{sub g} state to the 3d{sigma}{sub g} state through the intermediate five-photon coupling of the 1s{sigma}{sub g} and 2p{pi}{sub u} states at intense laser field with high frequency. Our computed value of the emission of D{sup +} ions in the perpendicular direction to that in the parallel direction of the laser polarization reasonably agrees with the recent experimental result of Chin and co-workers at the same laser parameters [Phys. Rev. A 62, 042708 (2000)].

  15. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas

    PubMed Central

    Gualda, Emilio J.; Vázquez de Aldana, Javier R.; Martínez-García, M. Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M.

    2011-01-01

    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures. PMID:22076258

  16. Sample-matrix effects in infrared laser neutral desorption, multiphoton-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beavis, R. C.; Lindner, J.; Grotemeyer, J.; Schlag, E. W.

    1988-05-01

    Sample-matrix effects in laser evaporation of intact neutral molecules (LEIM) prior to multiphoton ionization mass spectrometry (MUPI MS) are studied. The results show that a strong influence exists in adding matrix materials to the sample upon the desorption step. Using sugars as matrix leads to a suppression of pyrolysis products in small peptides by the laser desorption. As a result mass spectrometric signals due to the pyrolysis products are avoided.

  17. Multiphoton absorption in CsLiB6O10 with femtosecond infrared laser pulses

    NASA Astrophysics Data System (ADS)

    Reddy, J. N. Babu; Naik, V. B.; Elizabeth, Suja; Bhat, H. L.; Venkatram, N.; Rao, D. Narayana

    2008-09-01

    Nonlinear absorption and refraction characteristics of cesium lithium borate (CsLiB6O10) crystal have been studied using Z-scan technique. Ti:sapphire laser with 110 fs pulse width operating at 800 nm wavelength and pulse repetition rate of 1 kHz is used as the source of photons. Intensity of the laser pulse is varied from 0.541 to 1.283 T W/cm2 to estimate the intensity dependence of multiphoton absorption coefficients. Using the theory of multiphoton absorption proposed by Sutherland [Handbook of Nonlinear Optics, in 2nd ed., edited by D. G. McLean and S. Kirkpatrick, Dekker, New York (2003)], found that open aperture Z-scan data fit well for the five-photon absorption (5PA) process. 5PA coefficients are obtained by fitting the expressions into the open aperture experimental data for various peak intensities (I00). The nonlinear refractive index n2 estimated from closed aperture Z-scan experiment is 1.075×10-4 cm2/T W at an input peak intensity of 0.723 T W/cm2. The above experiment when repeated with a 532 nm, 6 ns pulsed laser led to an irreversible damage of the sample resulting in an asymmetric open aperture Z-scan profile. This indicates that it is not possible to observe multiphoton absorption in this regime of pulse width using 532 nm laser.

  18. Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study

    SciTech Connect

    Hoang Viet, Man; Roland, Christopher Sagui, Celeste; Derreumaux, Philippe; Nguyen, Phuong H.; Li, Mai Suan

    2015-10-21

    Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.

  19. Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study

    NASA Astrophysics Data System (ADS)

    Hoang Viet, Man; Derreumaux, Philippe; Li, Mai Suan; Roland, Christopher; Sagui, Celeste; Nguyen, Phuong H.

    2015-10-01

    Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.

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

    PubMed Central

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

    2010-01-01

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

  1. Infrared laser-based monitoring of the silane dissociation during deposition of silicon thin films

    SciTech Connect

    Bartlome, R.; Feltrin, A.; Ballif, C.

    2009-05-18

    The silane dissociation efficiency, or depletion fraction, is an important plasma parameter by means of which the film growth rate and the amorphous-to-microcrystalline silicon transition regime can be monitored in situ. In this letter we implement a homebuilt quantum cascade laser-based absorption spectrometer to measure the silane dissociation efficiency in an industrial plasma-enhanced chemical vapor deposition system. This infrared laser-based diagnostic technique is compact, sensitive, and nonintrusive. Its resolution is good enough to resolve Doppler-broadened rotovibrational absorption lines of silane. The latter feature various absorption strengths, thereby enabling depletion measurements over a wide range of process conditions.

  2. Tritium removal from contaminated water via infrared laser multiple-photon dissociation

    SciTech Connect

    Maienschein, J.L.; Magnotta, F.; Herman, I.P.; Aldridge, F.T.; Hsiao, P.

    1983-01-01

    Isotope separation by means of infrared-laser multiple-photon dissociation offers an efficient way to recover tritium from contaminated light or heavy water found in fission and fusion reactors. For tritium recovery from heavy water, chemical exchange of tritium into deuterated chloroform is followed by selective laser dissociation of tritiated chloroform and removal of the tritiated photoproduct, TCl. The single-step separation factor is at least 2700 and is probably greater than 5000. Here we present a description of the tritium recovery process, along with recent accomplishments in photochemical studies and engineering analysis of a recovery system.

  3. Kinetics of Mo atom formation and consumption in UV multiphoton dissociation of Mo(CO)6 at room temperature

    NASA Astrophysics Data System (ADS)

    Eremin, A. V.; Gurentsov, E. V.; Musikhin, S. A.

    2015-12-01

    This study is devoted to the investigation of molybdenum atom formation and consumption after UV laser pulse photolysis of molybdenum hexacarbonyl vapor diluted by various bath gases. The processes of formation and consumption of Mo atoms were observed using atomic resonance absorption spectroscopy (ARAS) technique at the Mo-I resonance line (λ = 386.41 nm) providing the time profiles of molybdenum atoms concentration in the ground state. The increase of Mo atoms concentration was detected immediately after laser pulse and was determined mainly by spontaneous radiative quenching of excited Mo atoms produced in photolysis of molybdenum hexacarbonyl. It was found that collision quenching with bath gas molecules played a minor role. The following decrease of Mo atoms concentration after a maximum was attributed to the reactions of recombination, cluster formation and other secondary reactions. Based on the experimental data obtained, the kinetic mechanism of Mo atoms formation and consumption in photo-dissociation of Mo(CO)6 was developed. The rate constants of basic reactions responsible for this mechanism were estimated using the frequencies of gas-kinetics collisions or were extracted directly from experimental data by the fitting of measured and calculated time profiles of Mo atoms concentration.

  4. Structural identification of electron transfer dissociation products in mass spectrometry using infrared ion spectroscopy.

    PubMed

    Martens, Jonathan; Grzetic, Josipa; Berden, Giel; Oomens, Jos

    2016-01-01

    Tandem mass spectrometry occupies a principle place among modern analytical methods and drives many developments in the 'omics' sciences. Electron attachment induced dissociation methods, as alternatives for collision-induced dissociation have profoundly influenced the field of proteomics, enabling among others the top-down sequencing of entire proteins and the analysis of post-translational modifications. The technique, however, produces more complex mass spectra and its radical-driven reaction mechanisms remain incompletely understood. Here we demonstrate the facile structural characterization of electron transfer dissociation generated peptide fragments by infrared ion spectroscopy using the tunable free-electron laser FELIX, aiding the elucidation of the underlying dissociation mechanisms. We apply this method to verify and revise previously proposed product ion structures for an often studied model tryptic peptide, [AlaAlaHisAlaArg+2H](2+). Comparing experiment with theory reveals that structures that would be assigned using only theoretical thermodynamic considerations often do not correspond to the experimentally sampled species. PMID:27277826

  5. Structural identification of electron transfer dissociation products in mass spectrometry using infrared ion spectroscopy

    PubMed Central

    Martens, Jonathan; Grzetic, Josipa; Berden, Giel; Oomens, Jos

    2016-01-01

    Tandem mass spectrometry occupies a principle place among modern analytical methods and drives many developments in the ‘omics' sciences. Electron attachment induced dissociation methods, as alternatives for collision-induced dissociation have profoundly influenced the field of proteomics, enabling among others the top-down sequencing of entire proteins and the analysis of post-translational modifications. The technique, however, produces more complex mass spectra and its radical-driven reaction mechanisms remain incompletely understood. Here we demonstrate the facile structural characterization of electron transfer dissociation generated peptide fragments by infrared ion spectroscopy using the tunable free-electron laser FELIX, aiding the elucidation of the underlying dissociation mechanisms. We apply this method to verify and revise previously proposed product ion structures for an often studied model tryptic peptide, [AlaAlaHisAlaArg+2H]2+. Comparing experiment with theory reveals that structures that would be assigned using only theoretical thermodynamic considerations often do not correspond to the experimentally sampled species. PMID:27277826

  6. Visible/Infrared Dissociation of NO3: Roaming in the Dark or Roaming on the Ground?

    PubMed

    Fernando, Ravin; Dey, Arghya; Broderick, Bernadette M; Fu, Bina; Homayoon, Zahra; Bowman, Joel M; Suits, Arthur G

    2015-07-16

    We present a DC slice imaging study of roaming dynamics in the photodissociation of the nitrate radical, NO3, contrasting pure visible excitation with a combination of visible and CO2 laser excitation at 10.6 μm. Images of specific rotational levels of NO are seen to reflect dissociation on the ground and first excited electronic states, as reported in previous work. The branching is obtained for specific rotational levels by comparison to quasiclassical trajectory calculations of the dynamics on these two surfaces. The results for the visible dissociation are found to be very similar to the combination of visible and infrared, raising questions about the nature of the coupling of these surfaces, the extent to which roaming takes place on both, and how the final product branching is determined. PMID:25407947

  7. Resonance multiphoton ionization and dissociation of dimethyl ether via the {\\skew1\\tilde{\\rm C}^{\\prime}}, {\\skew1\\tilde{\\rm C}} and \\tilde{\\rm B} states

    NASA Astrophysics Data System (ADS)

    Mejia-Ospino, E.; García, G.; Guerrero, A.; Alvarez, I.; Cisneros, C.

    2005-01-01

    The three-photon resonance four-photon ionization and dissociation spectra of dimethyl ether (DME) are presented in the wavelength range 450-550 nm at 1 nm intervals. The (3+1) REMPI spectra show three prominent bands corresponding to the \\tildeB \\leftarrow \\skew1\\tildeX, {\\skew1\\tildeC} \\leftarrow \\skew1\\tildeX and {\\skew1\\tildeC^{\\prime}} \\leftarrow \\skew1\\tildeX transitions with origins at 61 457 cm-1 (7.615 eV), 59 055 cm-1 (7.322 eV) and 58 010 cm-1 (7.194 eV), respectively. Several ionized species, CH3+, CHnO+ (n = 1-3) and CH3OCH3+, are observed in the region of wavelengths studied here. In order to compare the results, a shorter wavelength multiphoton dissociation and ionization of DME at 355 nm is also presented. At this wavelength, DME undergoes neutral dissociation to CH3 and CH3O and each fragment is then ionized by multiphoton absorption. The fragmentation at 355 nm is very intense and only small fragments such as CH3+, CHO+, CH2+, CH+ and C+ ions are observed. The measurement of photoelectron energy allows us to establish that the DME ionization potential is at least 9.55 ± 0.15 eV. The experiments were performed using a Nd:YAG-OPO (optical parametric oscillator) tunable laser system coupled to a time-of-flight mass spectrometer and a hemispherical electron energy analyser.

  8. Gas-Phase Structure of Amyloid-β (12 - 28) Peptide Investigated by Infrared Spectroscopy, Electron Capture Dissociation and Ion Mobility Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Le, Thi Nga; Poully, Jean Christophe; Lecomte, Frédéric; Nieuwjaer, Nicolas; Manil, Bruno; Desfrançois, Charles; Chirot, Fabien; Lemoine, Jerome; Dugourd, Philippe; van der Rest, Guillaume; Grégoire, Gilles

    2013-12-01

    The gas-phase structures of doubly and triply protonated Amyloid-β12-28 peptides have been investigated through the combination of ion mobility (IM), electron capture dissociation (ECD) mass spectrometry, and infrared multi-photon dissociation (IRMPD) spectroscopy together with theoretical modeling. Replica-exchange molecular dynamics simulations were conducted to explore the conformational space of these protonated peptides, from which several classes of structures were found. Among the low-lying conformers, those with predicted diffusion cross-sections consistent with the ion mobility experiment were further selected and their IR spectra simulated using a hybrid quantum mechanical/semiempirical method at the ONIOM DFT/B3LYP/6-31 g(d)/AM1 level. In ECD mass spectrometry, the c/z product ion abundance (PIA) has been analyzed for the two charge states and revealed drastic differences. For the doubly protonated species, N - Cα bond cleavage occurs only on the N and C terminal parts, while a periodic distribution of PIA is clearly observed for the triply charged peptides. These PIA distributions have been rationalized by comparison with the inverse of the distances from the protonated sites to the carbonyl oxygens for the conformations suggested from IR and IM experiments. Structural assignment for the amyloid peptide is then made possible by the combination of these three experimental techniques that provide complementary information on the possible secondary structure adopted by peptides. Although globular conformations are favored for the doubly protonated peptide, incrementing the charge state leads to a conformational transition towards extended structures with 310- and α-helix motifs.

  9. Infrared Multiple-Photon Dissociation spectroscopy of group II metal complexes with salicylate

    SciTech Connect

    Ryan P. Dain; Gary Gresham; Gary S. Groenewold; Jeffrey D. Steill; Jos Oomens; Michael J. van Stipdonk

    2011-07-01

    Ion-trap tandem mass spectrometry with collision-induced dissociation, and the combination of infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations were used to characterize singly-charged, 1:1 complexes of Ca2+, Sr2+ and Ba2+ with salicylate. For each metal-salicylate complex, the CID pathways are: (a) elimination of CO2 and (b) formation of [MOH]+ where M=Ca2+, Sr2+ or Ba2+. DFT calculations predict three minima for the cation-salicylate complexes which differ in the mode of metal binding. In the first, the metal ion is coordinated by O atoms of the (neutral) phenol and carboxylate groups of salicylate. In the second, the cation is coordinated by phenoxide and (neutral) carboxylic acid groups. The third mode involves coordination by the carboxylate group alone. The infrared spectrum for the metal-salicylate complexes contains a number of absorptions between 1000 – 1650 cm-1, and the best correlation between theoretical and experimental spectra for the structure that features coordination of the metal ion by phenoxide and the carbonyl group of the carboxylic acid group, consistent with calculated energies for the respective species.

  10. MULTIPHOTON PROCESSES

    SciTech Connect

    2002-07-05

    The Gordon Research Conference (GRC) on MULTIPHOTON PROCESSES was held at Tilton School, Tilton, NH. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  11. First in vivo animal studies on intraocular nanosurgery and multiphoton tomography with low-energy 80-MHz near-infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Konig, Karsten; Wang, Bagui; Krauss, Oliver; Riemann, Iris; Schubert, Harald; Kirste, Sigrun; Fischer, Peter

    2004-07-01

    We report on a method for refractive laser surgery based on low-energy femtosecond laser pulses provided by ultracompact turn-key non-amplified laser systems. An additional excimer laser is not required for ablation of the stroma. The novel method has the potential to be used for (i) optical flap creation as well as stroma ablation and (ii) for non-invasive flap-free intrastromal ablation. In addition, 3D multiphoton imaging of the cornea can be performed. In particular, we used sub-nanojoule near infrared 80 MHz femtosecond laser pulses for multiphoton imaging of corneal structures with ultrahigh resolution (< 1μm) as well as for highly precise intraocular refractive surgery. Imaging based on two-photon excited cellular autofluorescence and SHG formation in collagen structures was performed at GW/cm2 intensities, whereas destructive optical breakdown for nanoprocessing occurred at TW/cm2 light intensities. These high intensities were realized with sub-nJ pulses within a subfemtoliter intrastromal volume by diffraction-limited focussing with high NA objectives and beam scanning 50 to 140 μm below the epithelial surface. Multiphoton tomography of the cornea was used to determine the target of interest and to visualize intraocular post-laser effects. Histological examination with light- and electron microscopes of laser-exposed porcine and rabbit eyes reveal a minimum intratissue cut size below 1 μm without destructive effects to surrounding collagen structures. LASIK flaps and intracorneal cavities could be realized with high precision using 200 fs, 80 MHz, sub-nanojoule pulses at 800 nm. First studies on 80 MHz femtosecond laser surgery on living rabbits have been performed.

  12. Picosecond infrared laser-induced all-atom nonequilibrium molecular dynamics simulation of dissociation of viruses.

    PubMed

    Hoang Man, Viet; Van-Oanh, Nguyen-Thi; Derreumaux, Philippe; Li, Mai Suan; Roland, Christopher; Sagui, Celeste; Nguyen, Phuong H

    2016-04-28

    Since the discovery of the plant pathogen tobacco mosaic virus as the first viral entity in the late 1800s, viruses traditionally have been mainly thought of as pathogens for disease-resistances. However, viruses have recently been exploited as nanoplatforms with applications in biomedicine and materials science. To this aim, a large majority of current methods and tools have been developed to improve the physical stability of viral particles, which may be critical to the extreme physical or chemical conditions that viruses may encounter during purification, fabrication processes, storage and use. However, considerably fewer studies are devoted to developing efficient methods to degrade or recycle such enhanced stability biomaterials. With this in mind, we carry out all-atom nonequilibrium molecular dynamics simulation, inspired by the recently developed mid-infrared free-electron laser pulse technology, to dissociate viruses. Adopting the poliovirus as a representative example, we find that the primary step in the dissociation process is due to the strong resonance between the amide I vibrational modes of the virus and the tuned laser frequencies. This process is determined by a balance between the formation and dissociation of the protein shell, reflecting the highly plasticity of the virus. Furthermore, our method should provide a feasible approach to simulate viruses, which is otherwise too expensive for conventional equilibrium all-atom simulations of such very large systems. Our work shows a proof of concept which may open a new, efficient way to cleave or to recycle virus-based materials, provide an extremely valuable tool for elucidating mechanical aspects of viruses, and may well play an important role in future fighting against virus-related diseases. PMID:27071540

  13. Alkali Metal-Glucose Interaction Probed with Infrared Pre-Dissociation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kregel, Steven J.; Marsh, Brett; Zhou, Jia; Garand, Etienne

    2015-06-01

    The efficient extraction of cellulose from biomass and its subsequent conversion to glucose derivatives is an attractive goal in the field of energy science. However, current industrial methods require high ionic strength and harsh conditions. Ionic liquids (IL's) are a class of "green" compounds that have been shown to dissolve cellulose in concentrations of up to 25 wt%. In order to understand IL's extraordinary cellulose dissolving power, a molecular level understanding of the IL-cellulose interaction is needed. Toward that end, we have acquired infrared pre-dissociation spectra of M+-glucose, where M+=Li+, Na+, or K+. Through comparisons with density functional theory calculations, we have determined the relative abundances of various M+-glucose binding motifs in both the thermodynamic and kinetic limits. These results provide insight on the hydrogen bonding dynamics of glucose and are a step towards a fuller understanding of cellulose interactions with ionic liquids.

  14. Multiphoton near-infrared quantum cutting luminescence phenomena of Tm3+ ion in (Y1-xTm(x))3Al5O12 powder phosphor.

    PubMed

    Chen, Xiaobo; Salamo, Gregory J; Yang, Guojian; Li, Yongliang; Ding, Xianlin; Gao, Yan; Liu, Quanlin; Guo, Jinghua

    2013-09-01

    In the present study, the multiphoton near-infrared downconversion quantum cutting luminescence phenomena of Tm3+ ion in (Y(1-x)Tm(x))(3)Al(5)O(12) powder phosphor, which is currently a hot research topic throughout the world, is reported. The x-ray diffraction spectra, the visible to near-infrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that Tm:YAG powder phosphor has intense two-photon quantum cutting luminescence, and, for the first time, it is found that Tm:YAG powder phosphor has strong four-photon near-infrared quantum cutting luminescence of 1788 nm (3)F4 → (3)H6 fluorescence of Tm(3+) ion. It is also found that the theoretical up-limit of four-photon near-infrared quantum cutting efficiency is about 282.12%, which results from both the {(1)D2 → (3)F2, (3)H6 → (3)H4} and {(3)H4 → (3)F4, (3)H6 → (3)F4} cross-energy transfers. PMID:24104578

  15. Infrared Multiple Photon Dissociation Spectroscopy of Sodium and Potassium Chlorate Anions

    SciTech Connect

    Ryan P. Dain; Christopher M. Leavitt; Jos Oomens; Jeffrey D. Steill; Gary S. Groenewold; Michael J. van Stipdonk

    2010-01-01

    The structures of gas-phase, metal chlorate anions with the formula [M(ClO3)2]-, M=Na and K, were determined using tandem mass spectrometry and infrared multiple photon dissociation (IRMPD) spectroscopy. Structural assignments for both anions are based on comparisons of the experimental vibrational spectra for the two species to those predicted by density functional theory and involve conformations that feature either bidentate or tridentate coordination of the cation by chlorate. Our results strongly suggest that a structure in which both chlorate anions are bidentate ligands is preferred for [Na(ClO3)2]-. However, for [K(ClO3)2]- the best agreement between experimental and theoretical spectra is obtained from a composite of predicted spectra for which the chlorate anions are either both bidentate or both tridentate ligands. In general, we find that the overall accuracy of DFT calculations for prediction of IR spectra is dependent on both functional and basis set, with best agreement achieved using frequencies generated at the B3LYP/6-311+g(3df) level of theory.

  16. Infrared multiple photon dissociation spectroscopy of ciprofloxacin: Investigation of the protonation site

    NASA Astrophysics Data System (ADS)

    Bodo, E.; Ciavardini, A.; Giardini, A.; Paladini, A.; Piccirillo, S.; Rondino, F.; Scuderi, D.

    2012-04-01

    The vibrational spectrum of isolated protonated ciprofloxacin was recorded in the range 1100-2000 cm-1 by means of infrared multiple photon dissociation (IRMPD) spectroscopy. The spectrum was obtained by electrospraying a methanol solution of ciprofloxacin in a Paul ion trap, coupled to the tunable IR radiation of a free electron laser. This spectroscopic study has been complemented by quantum chemical calculations at the DFT and MP2 levels of theory to identify the possible structures present under our experimental conditions. Several low-energy isomers with protonation occurring at the piperazinyl amino group and at the carbonyl group are predicted in the energy range 0-84 kJ mol-1. A good agreement between the measured IRMPD spectrum and the calculated absorption spectrum is observed for the isomer protonated at the piperazinyl amino group. This isomer is calculated at MP2 level of theory to lie about 76 kJ/mol above the most stable isomer which is protonated at the quinone carbonyl group. This discrepancy can be rationalized by assuming that the protonation at the piperazinyl amino group, typical of the zwitterionic form that is found in protic solvents, is retained in the ESI process. The vibrational bands observed in the IRMPD spectrum are assigned to normal modes of the isomer protonated at the piperazinyl amino group, with deviations of less than 20 cm-1 between measured and calculated frequencies.

  17. Structure Determination of Cisplatin-Amino Acid Analogues by Infrared Multiple Photon Dissociation Action Spectroscopy

    NASA Astrophysics Data System (ADS)

    He, Chenchen; Bao, Xun; Zhu, Yanlong; Strobehn, Stephen; Kimutai, Bett; Nei, Y.-W.; Chow, C. S.; Rodgers, M. T.; Gao, Juehan; Oomens, J.

    2015-06-01

    To gain a better understanding of the binding mechanism and assist in the optimization of relevant drug and chemical probe design, both experimental and theoretical studies were performed on a series of amino acid-linked cisplatin derivatives, including glycine-, lysine-, and ornithine-linked cisplatin, Gplatin, Kplatin, and Oplatin, respectively. Cisplatin, the first FDA-approved platinum-based anticancer drug, has been widely used in cancer chemotherapy. Its pharmacological mechanism has been identified as its ability to coordinate to genomic DNA, and guanine is its major target. In previous reports, cisplatin was successfully utilized as a chemical probe to detect solvent accessible sites in ribosomal RNA (rRNA). Among the amino-acid-linked cisplatin derivatives, Oplatin exhibits preference for adenine over guanine. The mechanism behind its different selectivity compared to cisplatin may relate to its potential of forming a hydrogen bond between the carboxylate group in Pt (II) complex and the 6-amino moiety of adenosine stabilizes A-Oplatin products. Tandem mass spectrometry analysis also indicates that different coordination sites of Oplatin on adenosine affect glycosidic bond stability. Infrared multiple photon dissociation (IRMPD) action spectroscopy experiments were performed on all three amino acid-linked cisplatin to characterize their structures. An extensive theoretical study has been performed on Gplatin to guide the selection of the most effective theory and basis set based on its geometric information. The results for Gplatin provide the foundation for characterization of the more complex amino acid-linked cisplatin derivatives, Oplatin and Kplatin. Structural and energetic information elucidated for these compounds, particularly Oplatin reveal the reason for its alternative selectivity compared to cisplatin.

  18. Multiphoton ionization of Uracil

    NASA Astrophysics Data System (ADS)

    Prieto, Eladio; Martinez, Denhi; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2016-05-01

    Multiphoton ionization and dissociation of Uracil using a Reflectron time of flight spectrometer was performed along with radiation from the second harmonic of a Nd:YAG laser. Uracil is one of the four nitrogen bases that belong to RNA. The last years special interest has been concentrated on the study of the effects under UV radiation in nucleic acids1 and also in the role that this molecule could have played in the origin and development of life on our planet.2 The MPI mass spectra show that the presence and intensity of the resulting ions strongly depend on the density power. The identification of the ions in the mass spectra is presented. The results are compared with those obtained in other laboratories under different experimental conditions and some of them show partial agreement.3 The present work was supported by CONACYT-Mexico Grant 165410 and DGAPA UNAM Grant IN101215 and IN102613.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  20. Application of mid-infrared free-electron laser tuned to amide bands for dissociation of aggregate structure of protein.

    PubMed

    Kawasaki, Takayasu; Yaji, Toyonari; Ohta, Toshiaki; Tsukiyama, Koichi

    2016-01-01

    A mid-infrared free-electron laser (FEL) is a linearly polarized, high-peak powered pulse laser with tunable wavelength within the mid-infrared absorption region. It was recently found that pathogenic amyloid fibrils could be partially dissociated to the monomer form by the irradiation of the FEL targeting the amide I band (C=O stretching vibration), amide II band (N-H bending vibration) and amide III band (C-N stretching vibration). In this study, the irradiation effect of the FEL on keratin aggregate was tested as another model to demonstrate an applicability of the FEL for dissociation of protein aggregates. Synchrotron radiation infrared microscopy analysis showed that the α-helix content in the aggregate structure decreased to almost the same level as that in the monomer state after FEL irradiation tuned to 6.06 µm (amide I band). Both irradiations at 6.51 µm (amide II band) and 8.06 µm (amide III band) also decreased the content of the aggregate but to a lesser extent than for the irradiation at the amide I band. On the contrary, the irradiation tuned to 5.6 µm (non-absorbance region) changed little the secondary structure of the aggregate. Scanning-electron microscopy observation at the submicrometer order showed that the angular solid of the aggregate was converted to non-ordered fragments by the irradiation at each amide band, while the aggregate was hardly deformed by the irradiation at 5.6 µm. These results demonstrate that the amide-specific irradiation by the FEL was effective for dissociation of the protein aggregate to the monomer form. PMID:26698057

  1. Coherent control of D2/H2 dissociative ionization by a mid-infrared two-color laser field

    NASA Astrophysics Data System (ADS)

    Wanie, Vincent; Ibrahim, Heide; Beaulieu, Samuel; Thiré, Nicolas; Schmidt, Bruno E.; Deng, Yunpei; Alnaser, Ali S.; Litvinyuk, Igor V.; Tong, Xiao-Min; Légaré, François

    2016-01-01

    Steering the electrons during an ultrafast photo-induced process in a molecule influences the chemical behavior of the system, opening the door to the control of photochemical reactions and photobiological processes. Electrons can be efficiently localized using a strong laser field with a well-designed temporal shape of the electric component. Consequently, many experiments have been performed with laser sources in the near-infrared region (800 nm) in the interest of studying and enhancing the electron localization. However, due to its limited accessibility, the mid-infrared (MIR) range has barely been investigated, although it allows to efficiently control small molecules and even more complex systems. To push further the manipulation of basic chemical mechanisms, we used a MIR two-color (1800 and 900 nm) laser field to ionize H2 and D2 molecules and to steer the remaining electron during the photo-induced dissociation. The study of this prototype reaction led to the simultaneous control of four fragmentation channels. The results are well reproduced by a theoretical model solving the time-dependent Schrödinger equation for the molecular ion, identifying the involved dissociation mechanisms. By varying the relative phase between the two colors, asymmetries (i.e., electron localization selectivity) of up to 65% were obtained, corresponding to enhanced or equivalent levels of control compared to previous experiments. Experimentally easier to implement, the use of a two-color laser field leads to a better electron localization than carrier-envelope phase stabilized pulses and applying the technique in the MIR range reveals more dissociation channels than at 800 nm.

  2. INFRARED SPECTRUM OF POTASSIUM-CATIONIZED TRIETHYLPHOSPHATE GENERATED USING TANDEM MASS SPECTROMETRY AND INFRARED MULTIPLE PHOTON DISSOCIATION

    SciTech Connect

    Gary S. Groenewold; Christopher M. Leavitt; Ryan P. Dain; Jos Oomens; Jeff Steill; van Stipdonk, Michael J.

    2009-09-01

    Tandem mass spectrometry and wavelength selective infrared photodissociation was used to generate an infrared spectrum of gas-phase triethylphosphate cationized by attachment of K+. Prominent absorptions were observed in the region of 900 to 1300 cm-1 that are characteristic of phosphate P=O and P-O-R stretches. The relative positions and intensities of the IR absorptions were reproduced well by density functional theory (DFT) calculations performed using the B3LYP functional and the 6-31+g(d), 6-311+g(d,p) and 6-311++G(3df,2pd) basis sets. Because of good correspondence between experiment and theory for the cation, DFT was then used to generate a theoretical spectrum for neutral triethylphosphate, which in turn accurately reproduces the IR spectrum of the neat liquid when solvent effects are included in the calculations.

  3. Picosecond pulsed infrared laser tuned to amide I band dissociates polyglutamine fibrils in cells.

    PubMed

    Kawasaki, Takayasu; Ohori, Gaku; Chiba, Tomoyuki; Tsukiyama, Koichi; Nakamura, Kazuhiro

    2016-09-01

    Amyloid fibrils are causal substances for serious neurodegenerative disorders and amyloidosis. Among them, polyglutamine fibrils seen in multiple polyglutamine diseases are toxic to neurons. Although much efforts have been made to explore the treatments of polyglutamine diseases, there are no effective drugs to block progression of the diseases. We recently found that a free electron laser (FEL), which has an oscillation wavelength at the amide I band (C = O stretch vibration mode) and picosecond pulse width, was effective for conversion of the fibril forms of insulin, lysozyme, and calcitonin peptide into their monomer forms. However, it is not known if that is also the case in polyglutamine fibrils in cells. We found in this study that the fibril-specific β-sheet conformation of polyglutamine peptide was converted into nonfibril form, as evidenced by the infrared microscopy and scanning-electron microscopy after the irradiation tuned to 6.08 μm. Furthermore, irradiation at this wavelength also changed polyglutamine fibrils to their nonfibril state in cultured cells, as shown by infrared mapping image of protein secondary structure. Notably, infrared thermography analysis showed that temperature increase of the cells during the irradiation was within 1 K, excluding thermal damage of cells. These results indicate that the picosecond pulsed infrared laser can safely reduce amyloid fibril structure to the nonfibril form even in cells. PMID:27342599

  4. Infrared multiple-photon dissociation spectroscopy of tripositive ions: lanthanum-tryptophan complexes.

    PubMed

    Verkerk, Udo H; Zhao, Junfang; Saminathan, Irine S; Lau, Justin Kai-Chi; Oomens, Jos; Hopkinson, Alan C; Siu, K W Michael

    2012-04-16

    Collision-induced charge disproportionation limits the stability of triply charged metal ion complexes and has thus far prevented successful acquisition of their gas-phase IR spectra. This has curtailed our understanding of the structures of triply charged metal complexes in the gas phase and in biological environments. Herein we report the first gas-phase IR spectra of triply charged La(III) complexes with a derivative of tryptophan (N-acetyl tryptophan methyl ester), and an unusual dissociation product, a lanthanum amidate. These spectra are compared with those predicted using density functional theory. The best structures are those of the lowest energies that differ by details in the π-interaction between La(3+) and the indole rings. Other binding sites on the tryptophan derivative are the carbonyl oxygens. In the lanthanum amidate, La(3+) replaces an H(+) in the amide bond of the tryptophan derivative. PMID:22455512

  5. Multiphoton processes: conference proceedings

    SciTech Connect

    Lambropoulos, P.; Smith, S.J.

    1984-01-01

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

  6. Proposed photosynthesis method for producing hydrogen from dissociated water molecules using incident near-infrared light.

    PubMed

    Li, Xingxing; Li, Zhenyu; Yang, Jinlong

    2014-01-10

    Highly efficient solar energy utilization is very desirable in photocatalytic water splitting. However, until now, the infrared part of the solar spectrum, which constitutes almost half of the solar energy, has not been used, resulting in significant loss in the efficiency of solar energy utilization. Here, we propose a new mechanism for water splitting in which near-infrared light can be used to produce hydrogen. This ability is a result of the unique electronic structure of the photocatalyst, in which the valence band and conduction band are distributed on two opposite surfaces with a large electrostatic potential difference produced by the intrinsic dipole of the photocatalyst. This surface potential difference, acting as an auxiliary booster for photoexcited electrons, can effectively reduce the photocatalyst's band gap required for water splitting in the infrared region. Our electronic structure and optical property calculations on a surface-functionalized hexagonal boron-nitride bilayer confirm the existence of such photocatalysts and verify the reaction mechanism. PMID:24483934

  7. Infrared spectrum analysis of the dissociated states of simple amino acids

    NASA Astrophysics Data System (ADS)

    Sebben, Damien; Pendleton, Phillip

    2014-11-01

    In this work, we present detailed analyses of the dissociation of dilute aqueous solutions of glycine and of lysine over the range 1 < pH < 12. Using appropriate spectrum subtraction methods, we obtained ATR-IR spectra of the solvated species as a function of pH. Discernible changes in the ionic species were identified in the absorption region between 1800 and 1100 cm-1. By applying peak deconvolution techniques to the spectra, we correctly interpret the apparent peak shift from 1615 to 1600 cm-1 as being due to the receding NH3+ asymmetric deformation alongside the appearing COO- asymmetric stretching. The effect of aqueous solution environment was also investigated in terms of 10 and 100 mmol/L NaCl. Salt solution spectra at each pH were also subtracted from each solution phase spectrum. Analysis of the deconvoluted peak areas due to Cdbnd O and COO- at pH ranges < 4.5 and those due to NH2 and NH3+ for pH > 8 resulted in consistent pKa values for the amino acids.

  8. VUV pump - infrared probe studies of molecular dissociation following state-selective photoexcitation

    NASA Astrophysics Data System (ADS)

    Malakar, Y.; Kaderiya, B.; Pearson, W. L.; Kanaka Raju, P.; Li, Xiang; Cao, Wei; Ben-Itzhak, I.; Rudenko, A.; Trabert, D.; Wilhelm, F.

    2015-05-01

    Time-resolved measurements employing light sources based on high-harmonics generation are typically performed using broad-band pulses aiming at the shortest pulse duration achievable. This inherently results in a population of a superposition of states. In contrast, we employed ~ 100 fs VUV pulses with a narrow bandwidth of ~ 200 meV (filtered by a grating pair), to achieve state-selective excitation. We used 11th harmonic pump (centered at 17.3 eV) - 800 nm probe pulse sequence to trigger the dissociative ionization of O2 and CO2, which was characterized by energy- and angle-resolved photoion and photoelectron detection. While for the case of O2 the data can be understood in terms of the (net) absorption of one and two 800 nm photons from the VUV-excited ionic state, the preliminary CO2 results manifest rich dynamics, which surprisingly resembles the behavior observed in a recent experiment, where a comb of 11th to 17th harmonics was used. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Science, Office of Science, U.S. Department of Energy. K.R.P. supported by National Science Foundation Award No. IIA-1430493.

  9. Femtosecond infrared studies of the dissociation and dynamics of transition metal carbonyls in solution

    SciTech Connect

    Lian, T.; Bromberg, S.E.; Asplund, M.C.; Yang, H.; Harris C.B. |

    1996-07-18

    The ultrafast dynamics of the dissociation of M(CO){sub 6} (M = Cr, W, Mo) in alkane solutions were studied by femtosecond IR spectroscopy. After UV photolysis at 295 nm, both the bleach of the parent molecules and the absorption of the pentacarbonyl intermediate were probed with 240 fs time resolution. Oscillatory perturbed free induction decay signals before t = 0 were observed and well characterized by realistic parameters of the system. The bleach recovery dynamics were found to be wavelength dependent, indicating that hot parent molecules are formed and that the bleach recovery time is determined by the vibrational cooling time. The measured percentage bleach recovery in n-heptane is less than the expected value calculated from the photosubstitution quantum yield measurements, suggesting that the initial recovery of the bleach is faster than our time resolution. The kinetics in the A{sub 1} vibrational mode region of the pentacarbonyl species have been measured to probe the formation and decay of the nascent product. The absorption of the product rises with an instrument response limited rate indicating that the formation of the product is much faster than 240 fs. The long time kinetics in this region reflect the vibrational cooling of the product. A fast decay with time constant of less than 300 fs is present in all the wavelengths probed, and its spectrum appears to resemble the early time spectrum of the hot pentacarbonyl species. 44 refs., 8 figs.

  10. Infrared Multiple Photon Dissociation Spectroscopy of a Gas-Phase Oxo-Molybdenum Complex with 1,2-Dithiolene Ligands

    PubMed Central

    2015-01-01

    Electrospray ionization (ESI) in the negative ion mode was used to create anionic, gas-phase oxo-molybdenum complexes with dithiolene ligands. By varying ESI and ion transfer conditions, both doubly and singly charged forms of the complex, with identical formulas, could be observed. Collision-induced dissociation (CID) of the dianion generated exclusively the monoanion, while fragmentation of the monoanion involved decomposition of the dithiolene ligands. The intrinsic structure of the monoanion and the dianion were determined by using wavelength-selective infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The IRMPD spectrum for the dianion exhibits absorptions that can be assigned to (ligand) C=C, C–S, C—C≡N, and Mo=O stretches. Comparison of the IRMPD spectrum to spectra predicted for various possible conformations allows assignment of a pseudo square pyramidal structure with C2v symmetry, equatorial coordination of MoO2+ by the S atoms of the dithiolene ligands, and a singlet spin state. A single absorption was observed for the oxidized complex. When the same scaling factor employed for the dianion is used for the oxidized version, theoretical spectra suggest that the absorption is the Mo=O stretch for a distorted square pyramidal structure and doublet spin state. A predicted change in conformation upon oxidation of the dianion is consistent with a proposed bonding scheme for the bent-metallocene dithiolene compounds [Lauher, J. W.; Hoffmann, R. J. Am. Chem. Soc.1976, 98, 1729−1742], where a large folding of the dithiolene moiety along the S···S vector is dependent on the occupancy of the in-plane metal d-orbital. PMID:24988369

  11. Multiphoton Effects in Rutile.

    NASA Astrophysics Data System (ADS)

    Royce, Gerald A.

    Multiphoton effects are investigated in crystalline rutile TiO(,2) using Nd:YAG laser photons. The 1.06 micron laser is operated in Q-switched mode with intensities up to 1.4 x 10('6) watts/cm('2) on the rutile crystal. Photoconductivity measurements provide data indicating a mixture of modes for electrons to be photoionized. Assuming aluminum impurity as the contributing sites, the first order photionization cross section is found to be 1.5 x 10('-26) cm('2) and second order cross section is found to be 7.7 x 10('-51) cm('4)-s. No appreciable change in cross section is observed for circular versus linear polarization of the laser. Observations of the photo-emission of the laser illuminated crystal provide radiative relaxation times on the order of 100 nanoseconds with emission peaks at 4500 and 5000 angstroms plus a near infrared continuum out to 1 micron. The thermoluminescence of rutile shows a number of trapping levels between 0.4 and 0.8 eV below the conduction band. These are attributed to an aluminum impurity.

  12. Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Glutamine Complexes with Zn(2+) and Cd(2.).

    PubMed

    Boles, Georgia C; Coates, Rebecca A; Berden, Giel; Oomens, Jos; Armentrout, P B

    2015-09-01

    Complexes of glutamine (Gln) cationized with Zn(2+) and Cd(2+) were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free-electron laser. Electrospray ionization yielded complexes of deprotonated Gln with Zn(2+), [Zn(Gln-H)](+), and intact Gln with CdCl(+), CdCl(+)(Gln). For each complex, the spectra obtained were compared with those for low-energy conformers found using quantum chemical calculations to identify the structures present experimentally. Calculations were performed at the B3LYP/6-311+G(d,p) level for [Zn(Gln-H)](+) and at the B3LYP/def2-TZVP level with an SDD effective core potential on cadmium for CdCl(+)(Gln). The main binding motif observed for the Cd(2+) complex was a charge-solvated, tridentate [N,CO,COsc] structure in which the metal binds to the backbone amino group and the carbonyl oxygens of the carboxylic acid and side-chain amide groups. The Zn(2+) system similarly preferred a [N,CO(-),COsc] binding motif, where binding was observed at the carboxylate site along with the backbone amino and side-chain carbonyl groups. In both cases, the theoretically determined lowest-energy conformers explain the experimental [Zn(Gln-H)](+) and CdCl(+)(Gln) spectra well. PMID:26280573

  13. Structural elucidation of direct analysis in real time ionized nerve agent simulants with infrared multiple photon dissociation spectroscopy.

    PubMed

    Rummel, Julia L; Steill, Jeffrey D; Oomens, Jos; Contreras, Cesar S; Pearson, Wright L; Szczepanski, Jan; Powell, David H; Eyler, John R

    2011-06-01

    Infrared multiple photon dissociation (IRMPD) was used to generate vibrational spectra of ions produced with a direct analysis in real time (DART) ionization source coupled to a 4.7 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The location of protonation on the nerve agent simulants diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP) was studied while solutions of the compounds were introduced for extended periods of time with a syringe pump. Theoretical vibrational spectra were generated with density functional theory calculations. Visual comparison of experimental mid-IR IRMPD spectra and theoretical spectra could not establish definitively if a single structure or a mixture of conformations was present for the protonated parent of each compound. However, theoretical calculations, near-ir IRMPD spectra, and frequency-to-frequency and statistical comparisons indicated that the protonation site for both DIMP and DMMP was predominantly, if not exclusively, the phosphonyl oxygen instead of one of the oxygen atoms with only single bonds. PMID:21491962

  14. Dissociation dynamics of the CO2 molecule studied with XUV pump and near-infrared probe experiments

    NASA Astrophysics Data System (ADS)

    Pandiri, Kanaka Raju; Malakar, Yu; Li, Xiang; Kaderiya, Balram; Pearson, Wright; Cao, Wei; Ben-Itzhak, Itzik; Rolles, Daniel; Rudenko, Artem; Trapp, Philip; Trabert, Daniel; Wilhelm, Florian

    2016-05-01

    Ultrafast dynamics of ionic states of the CO2 molecule have recently been studied by employing a pump-probe technique using broadband ultrashort XUV-pump pulses containing the 11th to 17th harmonics of a near-infrared laser (NIR). Here, we present the results of a complimentary experiment employing longer (~100 fs) but narrowband, single harmonic (11th or 13th) pulses to excite molecular wave packets to specific states of CO2+,which are probed by NIR-induced dissociation. We employ a reaction microscope to measure energy- and angle-resolved yields of all charged reaction fragments as a function of XUV-NIR delay. In particular, the delay dependence of O+ and CO+ ion production for parallel and perpendicular NIR and XUV polarizations are contrasted with the data obtained by Timmers et al. using ultrashort broadband train of harmonics. This project is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy. K. R. P. and W. L. P. are supported by National Foundation Award No. IIA-143049.

  15. Zn(2+) and Cd(2+) cationized serine complexes: infrared multiple photon dissociation spectroscopy and density functional theory investigations.

    PubMed

    Coates, Rebecca A; Boles, Georgia C; McNary, Christopher P; Berden, Giel; Oomens, Jos; Armentrout, P B

    2016-08-10

    The gas-phase structures of zinc and cadmium dications bound to serine (Ser) are investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using the free electron laser FELIX, in combination with ab initio calculations. To identify the structures of the experimentally observed species, [Zn(Ser-H)CH3CN](+) and CdCl(+)(Ser), the measured action spectra are compared to linear absorption spectra calculated at the B3LYP/6-311+G(d,p) level for Zn(2+) containing complexes and B3LYP/def2-TZVP levels for Cd(2+) containing complexes. Good agreement between the observed IRMPD spectra and the predicted spectra allows identification of the isomers present. The intact amino acid interacting with cadmium chloride adopts a tridentate chelation involving the amino acid backbone amine and carbonyl groups as well as the hydroxyl group of the side-chain, [N,CO,OH]. The presence of two low-energy conformers is observed for the deprotonated serine-zinc complex, with the same tridentate coordination as for the cadmium complex but proton loss occurs at both the hydroxyl side-chain, [N,CO,O(-)], and the carboxylic acid of the amino acid backbone, [N,CO(-),OH]. These results are profitably compared with the analogous results previously obtained for comparable complexes with cysteine. PMID:27465924

  16. Gas phase infrared multiple photon dissociation spectra of positively charged sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle-like aggregates.

    PubMed

    Giorgi, Gianluca; Ceraulo, Leopoldo; Berden, Giel; Oomens, Jos; Liveri, Vincenzo Turco

    2011-03-17

    The capability of infrared multiple photon dissociation (IRMPD) spectroscopy to gain structural information on surfactant-based supramolecular aggregates has been exploited to elucidate intermolecular interactions and local organization of positively charged sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) aggregates in the gas phase. A detailed analysis of the stretching modes of the AOTNa CO and SO(3)(-) head groups allows one to directly probe their interactions with sodium counterions and to gain insight in their organization within the aggregate. Similarities and differences of the IRMPD spectra as compared to the infrared absorption spectrum of micellized AOTNa in CCl(4) have been analyzed. They strongly suggest a reverse micelle-like organization of AOTNa charged aggregates in the gas phase. Apart from low-abundance fragmentation channels of the AOTNa (molecule) itself, the main dissociation pathway of singly charged surfactant aggregates is the loss of neutral surfactant molecules, while doubly charged aggregates dissociate preferentially by charge separation forming singly charged species. In both cases, decomposition leads to the formation of the most energetically stable charged fragments. PMID:21341816

  17. Differentiation of Rubidiated Methyl-d-Glycoside Stereoisomers by Infrared Multiple-Photon Dissociation Spectroscopy in the O-H and C-H Stretching Regions.

    PubMed

    Pearson, Wright L; Contreras, Cesar; Powell, David; Berden, Giel; Oomens, Jos; Bendiak, Brad; Eyler, John R

    2015-10-15

    Four isomeric sugar methylglycosides (α- and β-d-gluco- and galactopyranosides) were evaluated as rubidium cation coordination adducts in the gas phase using variable-wavelength multiple-photon dissociation in the range from 2750 to 3750 cm(-1). The adducts dissociated following photon absorption to yield neutral sugars and the rubidium cation, resulting in infrared "action" spectra. Well-resolved hydroxyl stretching bands clearly differentiate stereoisomers that vary solely in their asymmetry at single carbons. Density functional theory calculations of the lowest-energy gas-phase complexes indicate that rubidium coordinates with lone pairs of oxygen atoms as either bi- or tridentate complexes and that more than one positional coordination isomer could adequately account for most of the O-H stretch frequencies observed for each methylglycoside. PMID:26393375

  18. In vivo multiphoton tomography of inflammatory tissue and melanoma

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  19. Multiphoton-Excited Serotonin Photochemistry

    PubMed Central

    Gostkowski, Michael L.; Allen, Richard; Plenert, Matthew L.; Okerberg, Eric; Gordon, Mary Jane; Shear, Jason B.

    2004-01-01

    We report photochemical and photophysical studies of a multiphoton-excited reaction of serotonin that previously has been shown to generate a photoproduct capable of emitting broadly in the visible spectral region. The current studies demonstrate that absorption of near-infrared light by an intermediate state prepared via three-photon absorption enhances the photoproduct formation yield, with the largest action cross sections (∼10−19 cm2) observed at the short-wavelength limit of the titanium:sapphire excitation source. The intermediate state is shown to persist for at least tens of nanoseconds and likely to be different from a previously reported oxygen-sensitive intermediate. In addition, the two-photon fluorescence action spectrum for the fluorescent photoproduct was determined and found to have a maximum at ∼780 nm (3.2 eV). A general mechanism for this photochemical process is proposed. PMID:15111435

  20. Multiphoton ionization of uranium hexafluoride

    NASA Astrophysics Data System (ADS)

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

    1994-01-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy (TOFMS) and photoelectron spectroscopy (PES) studies of UF6 are reported using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF+x fragment ions, even at the lowest laser power densities at which signal could be detected. In general, the doubly charged uranium ion (U2+) intensity is much greater than that of the singly charged uranium ion (U+). For the case of the tunable dye laser experiments, the Un+ (n=1-4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The MPI-PES studies reveal only very slow electrons (≤0.5 eV) for all wavelengths investigated. The dominance of the U2+ ion, the absence or very small intensities of UF+x (x=1-3) fragments, the unstructured wavelength dependence, and the preponderance of slow electrons all indicate that mechanisms may exist other than ionization of bare U atoms following the stepwise photodissociation of F atoms from the parent molecule. The data also argue against stepwise photodissociation of UF+x (x=5,6) ions. Neither of the traditional MPI mechanisms (``neutral ladder'' or the ``ionic ladder'') are believed to adequately describe the ionization phenomena observed. We propose that the multiphoton excitation of UF6 under these experimental conditions results in a highly excited molecule, superexcited UF6**. The excitation of highly excited UF6** is proposed to be facilitated by the well known ``giant resonance,'' whose energy level lies in the range of 12-14 eV above that of ground state UF6. The highly excited molecule then primarily dissociates, via multiple channels, into Un+, UF+x, fluorine atoms, and ``slow'' electrons, although dissociation

  1. In vivo multiphoton tomography of skin cancer

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  2. Multiphoton tomography to detect chemo- and biohazards

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2015-03-01

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

  3. Hybrid quadrupole mass filter/quadrupole ion trap/time-of-flight-mass spectrometer for infrared multiple photon dissociation spectroscopy of mass-selected ions

    SciTech Connect

    Gulyuz, Kerim; Stedwell, Corey N.; Wang Da; Polfer, Nick C.

    2011-05-15

    We present a laboratory-constructed mass spectrometer optimized for recording infrared multiple photon dissociation (IRMPD) spectra of mass-selected ions using a benchtop tunable infrared optical parametric oscillator/amplifier (OPO/A). The instrument is equipped with two ionization sources, an electrospray ionization source, as well as an electron ionization source for troubleshooting. This hybrid mass spectrometer is composed of a quadrupole mass filter for mass selection, a reduced pressure ({approx}10{sup -5} Torr) quadrupole ion trap (QIT) for OPO irradiation, and a reflectron time-of-flight drift tube for detecting the remaining precursor and photofragment ions. A helium gas pulse is introduced into the QIT to temporarily increase the pressure and hence enhance the trapping efficiency of axially injected ions. After a brief pump-down delay, the compact ion cloud is subjected to the focused output from the continuous wave OPO. In a recent study, we implemented this setup in the study of protonated tryptophan, TrpH{sup +}, as well as collision-induced dissociation products of this protonated amino acid [W. K. Mino, Jr., K. Gulyuz, D. Wang, C. N. Stedwell, and N. C. Polfer, J. Phys. Chem. Lett. 2, 299 (2011)]. Here, we give a more detailed account on the figures of merit of such IRMPD experiments. The appreciable photodissociation yields in these measurements demonstrate that IRMPD spectroscopy of covalently bound ions can be routinely carried out using benchtop OPO setups.

  4. Electron capture dissociation mass spectrometry of metallo-supramolecular complexes.

    PubMed

    Kaczorowska, Malgorzata A; Hotze, Anna C G; Hannon, Michael J; Cooper, Helen J

    2010-02-01

    The electron capture dissociation (ECD) of metallo-supramolecular dinuclear triple-stranded helicate Fe(2)L(3)(4+) ions was determined by Fourier transform ion cyclotron resonance mass spectrometry. Initial electron capture by the di-iron(II) triple helicate ions produces dinuclear double-stranded complexes analogous to those seen in solution with the monocationic metal centers Cu(I) or Ag(I). The gas-phase fragmentation behavior [ECD, collision-induced dissociation (CID), and infrared multiphoton dissociation (IRMPD)] of the di-iron double-stranded complexes, (i.e., MS(3) of the ECD product) was compared with the ECD, CID, and IRMPD of the Cu(I) and Ag(I) complexes generated from solution. The results suggest that iron-bound dimers may be of the form Fe(I)(2)L(2)(2+) and that ECD by metallo-complexes allows access, in the gas phase, to oxidation states and coordination chemistry that cannot be accessed in solution. PMID:20004114

  5. Multiphoton microscopy in neuroscience

    NASA Astrophysics Data System (ADS)

    Denk, Winfried

    2002-06-01

    The study of the nervous system requires to an exceptional extent observation of and experimentation on intact tissue. There, in particular, high-resolution optical microscopy benefits from the inherent advantages of multi-photon fluorescence excitation. Several cases will be presented from a number of different tissues and organisms, where multi-photon excited laser scanning fluorescence microscopy has been an essential experimental tool. Those examples include the discovery of biochemical coincidence detection in synaptic spines and the clarification of the underlying mechanism; the observation of sensory evoked dendritic signaling in intact animals and the observation of light induced calcium signals in the intact retina. Recently a fiber coupled two-photon microscopy has been developed that allows the imaging in moving animal.

  6. Clinical multiphoton FLIM tomography

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2012-03-01

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

  7. Photodissociation of gaseous CH3COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

    NASA Astrophysics Data System (ADS)

    Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen

    2013-01-01

    Upon one-photon excitation at 248 nm, gaseous CH3C(O)SH is dissociated following three pathways with the products of (1) OCS + CH4, (2) CH3SH + CO, and (3) CH2CO + H2S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state 1(nO, π*CO) has a radiative lifetime of 249 ± 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 × 10-10 cm3 molecule-1 s-1. Among the primary dissociation products, a fraction of the CH2CO moiety may undergo further decomposition to CH2 + CO, of which CH2 is confirmed by reaction with O2 producing CO2, CO, OH, and H2CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 ± 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

  8. High-resolution multimodal clinical multiphoton tomography of skin

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2011-03-01

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

  9. Multifocal multiphoton microscopy with adaptive optical correction

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  10. Photodissociation of gaseous CH{sub 3}COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

    SciTech Connect

    Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen

    2013-01-07

    Upon one-photon excitation at 248 nm, gaseous CH{sub 3}C(O)SH is dissociated following three pathways with the products of (1) OCS + CH{sub 4}, (2) CH{sub 3}SH + CO, and (3) CH{sub 2}CO + H{sub 2}S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state {sup 1}(n{sub O}, {pi}{sup *}{sub CO}) has a radiative lifetime of 249 {+-} 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 Multiplication-Sign 10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1}. Among the primary dissociation products, a fraction of the CH{sub 2}CO moiety may undergo further decomposition to CH{sub 2}+ CO, of which CH{sub 2} is confirmed by reaction with O{sub 2} producing CO{sub 2}, CO, OH, and H{sub 2}CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 {+-} 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

  11. State-selective vibrational excitation and dissociation of H2+ by strong infrared laser pulses: below-resonant versus resonant laser fields and electron-field following.

    PubMed

    Paramonov, Guennaddi K; Kühn, Oliver

    2012-11-26

    The quantum dynamics of vibrational excitation and dissociation of H(2)(+) by strong and temporally shaped infrared (IR) laser pulses has been studied on the femtosecond (fs) time scale by numerical solution of the time-dependent Schrödinger equation with explicit treatment of nuclear and electron motion beyond the Born-Oppenheimer approximation. Using sin(2)-shaped laser pulses of 120 fs duration with a peak intensity of I(0) > 10(14) W/cm(2), it has been found that below-resonant vibrational excitation with a laser carrier frequency of ω < ω(10)/2 (where ω(10) is the frequency of the |v = 0> → |v = 1> vibrational transition) is much more efficient than a quasi-resonant vibrational excitation at ω ≈ ω(10). In particular, at the below-resonant laser carrier frequency ω = 0.3641 × 10(-2) au (799.17 cm(-1)), dissociation probabilities of H(2)(+) (15.3% at the end of the 120 fs laser pulse and 21% at t = 240 fs) are more than 3 orders of magnitude higher than those obtained for the quasi-resonant laser frequency ω = 1.013 × 10(-2) au (2223.72 cm(-1)). Probabilities of state-selective population transfer to vibrational states |v = 1>, |v = 2>, and |v = 3> from the vibrational ground state |v = 0> of about 85% have been calculated in the optimal below-resonant cases. The underlying mechanism of the efficient below-resonant vibrational excitation is the electron-field following and simultaneous transfer of energy to the nuclear coordinate. PMID:22916791

  12. Action Spectroscopy and Dissociation Energy of Ammonia Trimer

    NASA Astrophysics Data System (ADS)

    Heid, Cornelia G.; Case, Amanda S.; Western, Colin M.; Crim, F. Fleming

    2012-06-01

    We have investigated the energy dependence for the vibrational predissociation of ammonia trimer, (NH_3)_3 → (NH_3)_2 + NH_3, using infrared-action spectroscopy. The action spectra come from detecting specific rovibrational states of the monomer fragment via (2+1) resonance enhanced multiphoton excitation (REMPI) while scanning the IR excitation laser over the NH stretch transitions of the trimer as well as the dimer. The relative intensities of the dimer and trimer features in the action spectra depend on the amount of energy available for breaking the hydrogen bonds in the clusters. For example, the action spectra of ammonia fragments with large amounts of internal energy (v_2=3) show almost no trimer contribution since there is not enough energy available to break two bonds in the cyclic trimer. The action spectra for fragments with low internal energies (v_2=1), on the other hand, exhibit a substantial trimer component as more energy remains available to dissociate the cluster. Using the threshold at which the trimer feature becomes apparent in our spectra as an upper limit (Edissmax = hνvib-Eint(NH_3)), we determine the dissociation energy of ammonia trimer to be in the range between 1700-1800 cm-1. This range agrees well with theoretical predictions.

  13. Calculation of multiphoton ionization processes

    NASA Technical Reports Server (NTRS)

    Chang, T. N.; Poe, R. T.

    1976-01-01

    We propose an accurate and efficient procedure in the calculation of multiphoton ionization processes. In addition to the calculational advantage, this procedure also enables us to study the relative contributions of the resonant and nonresonant intermediate states.

  14. Structural characterization of gas-phase cysteine and cysteine methyl ester complexes with zinc and cadmium dications by infrared multiple photon dissociation spectroscopy.

    PubMed

    Coates, Rebecca A; McNary, Christopher P; Boles, Georgia C; Berden, Giel; Oomens, Jos; Armentrout, P B

    2015-10-21

    Structural characterization of gas-phase ions of cysteine (Cys) and cysteine methyl ester (CysOMe) complexed to zinc and cadmium is investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using a free electron laser in combination with density functional theory calculations. IRMPD spectra are measured for [Zn(Cys-H)](+), [Cd(Cys-H)](+), [Zn(CysOMe-H)](+), [Cd(CysOMe-H)](+) and CdCl(+)(CysOMe) and are accompanied by quantum mechanical calculations of the predicted linear absorption spectra at the B3LYP/6-311+G(d,p) (Zn(2+) complexes) and B3LYP/def2TZVP levels (Cd(2+) complexes). On the basis of these experiments and calculations, the conformation that best reproduces the IRMPD spectra for the complexes of the deprotonated amino acids, [M(Cys-H)](+) and [M(CysOMe-H)](+), is a charge-solvated (CS) tridentate structure where the metal dication binds to the amine and carbonyl groups of the amino acid backbone and the deprotonated sulfur atom of the side chain, [N,CO,S(-)]. The intact amino acid complex, CdCl(+)(CysOMe) binds in the equivalent motif [N,CO,S]. These binding motifs are in agreement with the predicted ground structures of these complexes at the B3LYP, B3LYP-GD3BJ (with empirical dispersion corrections), B3P86, and MP2(full) levels. PMID:25880327

  15. Self-pairing of 1-methylthymine mediated by two and three Ag(i) ions: a gas phase study using infrared dissociation spectroscopy and density functional theory.

    PubMed

    Nosenko, Yevgeniy; Riehn, Christoph; Niedner-Schatteburg, Gereon

    2016-03-16

    Metal base pairs of Ag(I) cations and 1-methylthymine (1MT) or deprotonated 1-methylthymine (1MT-H) are produced and analyzed by electrospray ionization mass spectrometry (ESI-MS). Mass-selected ions of type [Ag2(1MT)(1MT-H)](+) and [Ag3(1MT-H)2](+) are interrogated by infrared multiple-photon dissociation (IRMPD) in an ion trap in the range of 1200-3700 cm(-1). Supporting spectroscopic data were obtained from the investigation of the analogous 2'-deoxy-thymidine complexes which exhibit advantageously high fragment yields. By comparison with calculated linear IR spectra (obtained by density functional theory, DFT) we assign the structures and the possible isomeric forms of these metal base pairs and their dependence on the number of mediating Ag(I) ions. Based on the observed Ag(+)/1MT complexes and related polarizable continuum model DFT calculations we describe the probable formation pathways in aqueous solution. The present findings pave the way for subsequent UV investigations of the multi-metal mediated base pairs. PMID:26940234

  16. Evaluation of Hybrid Theoretical Approaches for Structural Determination of a Glycine-Linked Cisplatin Derivative via Infrared Multiple Photon Dissociation (IRMPD) Action Spectroscopy.

    PubMed

    He, C C; Kimutai, B; Bao, X; Hamlow, L; Zhu, Y; Strobehn, S F; Gao, J; Berden, G; Oomens, J; Chow, C S; Rodgers, M T

    2015-11-01

    To gain a better understanding of the binding mechanism and assist in the optimization of chemical probing and drug design applications, experimental and theoretical studies of a series of amino acid-linked cisplatin derivatives are being pursued. Glyplatin (glycine-linked cisplatin) was chosen for its structural simplicity and to enable backbone effects to be separated from side-chain effects on the structure and reactivity of ornithine- and lysine-linked cisplatin (Ornplatin and Lysplatin, respectively). Infrared multiple photon dissociation (IRMPD) action spectroscopy experiments were performed on Glyplatin to characterize its structure and guide the selection of the most effective hybrid theoretical approach for determining its structure and IR spectrum. The simplicity of the Glyplatin system allows a wide variety of density functionals, treatments of the Pt center including the use of all-electron basis sets vs valence basis sets combined with an effective core potential (ECP), and basis sets for all other atoms to be evaluated at a reasonable computational cost. The results for Glyplatin provide the foundation for calculations of more complex amino acid-linked cisplatin derivatives such as Ornplatin and Lysplatin. Present results suggest that the B3LYP/mDZP/def2-TZVP hybrid method can be effectively employed for structural and IR characterization of more complex amino acid-linked cisplatin complexes and their nucleic acid derivatives. PMID:26473433

  17. Multiphoton tomography of astronauts

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  18. Quantitative multiphoton imaging

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  19. Multiphoton nanosurgery in cells and tissues

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  20. Advances in multiphoton microscopy technology

    PubMed Central

    Hoover, Erich E.; Squier, Jeff A.

    2013-01-01

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

  1. Multiphoton microspectroscopy of biological specimens

    NASA Astrophysics Data System (ADS)

    Lin, Bai-Ling; Kao, Fu-Jen; Cheng, Ping C.; Sun, Chi-Kuang; Chen, RangWu; Wang, YiMin; Chen, JianCheng; Wang, Yung-Shun; Liu, Tzu-Ming; Huang, Mao-Kuo

    2000-07-01

    The non-linear nature of multi-photon fluorescence excitation restricts the fluorescing volume to the vicinity of the focal point. As a result, the technology has the capacity for micro- spectroscopy of biological specimen at high spatial resolution. Chloroplasts in mesophyll protoplast of Arabidopsis thaliana and maize stem sections were used to demonstrate the feasibility of multi-photon fluorescence micro-spectroscopy at subcellular compartments. Time-lapse spectral recording provides a means for studying the response of cell organelles to high intensity illumination.

  2. Rapid electron capture dissociation of mass-selectively accumulated oligodeoxynucleotide dications

    NASA Astrophysics Data System (ADS)

    Schultz, Kristin N.; Håkansson, Kristina

    2004-05-01

    We have performed extended characterization of the fragmentation patterns of oligodeoxynucleotide dications following electron capture dissociation (ECD) utilizing improved instrumentation. Our current results from a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer equipped with mass-selective external ion accumulation and an indirectly heated dispenser cathode electron source demonstrate much richer fragmentation than from a previous 7 T instrument with a directly heated filament electron source. We propose the previous absence of backbone product ions from purine-containing oligonucleotides is a result of intramolecular hydrogen bonding, preventing product ions from separating. Similar behavior is observed at non-optimized ECD conditions with the current instrumentation. However, infrared laser heating of the resulting charge-reduced radical species results in extensive backbone fragmentation (different from infrared multiphoton dissociation) of the oligonucleotide dA6, demonstrating potential for ECD to characterize nucleic acid secondary structure. Under more optimized conditions, rich fragmentation, mostly in terms of w, (a/z-B), and (c/x-B) products, is observed for dA6, dC6, dG5, and d(GCATGC) following ECD only, allowing complete sequencing in several cases. The current ECD spectra contain some doubly charged products, indicating that populations of gas-phase oligodeoxynucleotide dications are zwitterionic.

  3. A simple model of multiphoton micromachining in silk hydrogels

    NASA Astrophysics Data System (ADS)

    Applegate, Matthew B.; Alonzo, Carlo; Georgakoudi, Irene; Kaplan, David L.; Omenetto, Fiorenzo G.

    2016-06-01

    High resolution three-dimensional voids can be directly written into transparent silk fibroin hydrogels using ultrashort pulses of near-infrared (NIR) light. Here, we propose a simple finite-element model that can be used to predict the size and shape of individual features under various exposure conditions. We compare predicted and measured feature volumes for a wide range of parameters and use the model to determine optimum conditions for maximum material removal. The simplicity of the model implies that the mechanism of multiphoton induced void creation in silk is due to direct absorption of light energy rather than diffusion of heat or other photoproducts, and confirms that multiphoton absorption of NIR light in silk is purely a 3-photon process.

  4. Spondylopelvic dissociation.

    PubMed

    Sullivan, Matthew P; Smith, Harvey E; Schuster, James M; Donegan, Derek; Mehta, Samir; Ahn, Jaimo

    2014-01-01

    Spondylopelvic dissociation is a complex injury pattern resulting in multiplanar instability of the lumbopelvis. These injuries have traditionally been known as "suicide jumper's fractures" and have recently increased in prevalence as a result of under-vehicle explosions seen in the past decade of military conflicts in the Middle East. The hallmarks of spondylopelvic dissociation are bilateral vertical sacral fractures with a horizontal component, resulting in lumbosacral instability in the sagittal and axial planes. Surgical treatment has evolved greatly and both percutaneous and open options are available, with triangular osteosynthesis being the most relied on method of fixation. PMID:24267208

  5. Stochastic scanning multiphoton multifocal microscopy.

    PubMed

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

    2006-04-17

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

  6. Record Multiphoton Absorption Cross-Sections by Dendrimer Organometalation.

    PubMed

    Simpson, Peter V; Watson, Laurance A; Barlow, Adam; Wang, Genmiao; Cifuentes, Marie P; Humphrey, Mark G

    2016-02-12

    Large increases in molecular two-photon absorption, the onset of measurable molecular three-photon absorption, and record molecular four-photon absorption in organic π-delocalizable frameworks are achieved by incorporation of bis(diphosphine)ruthenium units with alkynyl linkages. The resultant ruthenium alkynyl-containing dendrimers exhibit strong multiphoton absorption activity through the biological and telecommunications windows in the near-infrared region. The ligated ruthenium units significantly enhance solubility and introduce fully reversible redox switchability to the optical properties. Increasing the ruthenium content leads to substantial increases in multiphoton absorption properties without any loss of optical transparency. This significant improvement in multiphoton absorption performance by incorporation of the organometallic units into the organic π-framework is maintained when the relevant parameters are scaled by molecular weights or number of delocalizable π-electrons. The four-photon absorption cross-section of the most metal-rich dendrimer is an order of magnitude greater than the previous record value. PMID:26797727

  7. Multiphoton microscopy of atheroslcerotic plaques

    NASA Astrophysics Data System (ADS)

    Lilledahl, Magnus B.; de Lange Davies, Catharina; Haugen, Olav A.; Svaasand, Lars O.

    2007-02-01

    Multiphoton microscopy is a techniques that fascilitates three dimensional imaging of intact, unstained tissue. Especially connective tissue has a relatively strong nonlinear optical response and can easily be imaged. Atherosclerosis is a disease where lipids accumulate in the vessel wall and there is a thickening of the intima by growth of a cap of connective tissue. The mechanical strength of this fibrous cap is of clinically importance. If the cap ruptures a thrombosis forms which can block a coronary vessel and therby causing myocardial infarction. Multiphoton microscopy can be used to image the fibrous cap and thereby determine the thickness of the cap and the structure of the connective fibres. This could possibly be developed into a diagnostic and clincal tool to monitor the vulnerability of a plaque and also to better understand the development of a plaque and effects of treatment. We have collected multiphoton microscopy images from atherosclerotic plaque in human aorta, both two photon excited fluorescens and second harmonic generated signal. The feasability of using this technique to determine the state of the plaque is explored.

  8. Multiphoton adaptation of a commercial low-cost confocal microscope for live tissue imaging

    NASA Astrophysics Data System (ADS)

    Mancuso, James J.; Larson, Adam M.; Wensel, Theodore G.; Saggau, Peter

    2009-05-01

    The Nikon C1 confocal laser scanning microscope is a relatively inexpensive and user-friendly instrument. We describe a straightforward method to convert the C1 for multiphoton microscopy utilizing direct coupling of a femtosecond near-infrared laser into the scan head and fiber optic transmission of emission light to the three-channel detector box. Our adapted system can be rapidly switched between confocal and multiphoton mode, requires no modification to the original system, and uses only a few custom-made parts. The entire system, including scan mirrors and detector box, remain under the control of the user-friendly Nikon EZ-C1 software without modification.

  9. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

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

    PubMed Central

    Yew, Elijah; Rowlands, Christopher

    2014-01-01

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

  11. Multiphoton cryo microscope with sample temperature control

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    PubMed

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

    2015-01-12

    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

  13. Top-Down Mass Analysis of Protein Tyrosine Nitration: Comparison of Electron Capture Dissociation with “Slow-Heating” Tandem Mass Spectrometry Methods

    PubMed Central

    2010-01-01

    Tyrosine nitration in proteins is an important post-translational modification (PTM) linked to various pathological conditions. When multiple potential sites of nitration exist, tandem mass spectrometry (MS/MS) methods provide unique tools to locate the nitro-tyrosine(s) precisely. Electron capture dissociation (ECD) is a powerful MS/MS method, different in its mechanisms to the “slow-heating” threshold fragmentation methods, such as collision-induced dissociation (CID) and infrared multiphoton dissociation (IRMPD). Generally, ECD provides more homogeneous cleavage of the protein backbone and preserves labile PTMs. However recent studies in our laboratory demonstrated that ECD of doubly charged nitrated peptides is inhibited by the large electron affinity of the nitro group, while CID efficiency remains unaffected by nitration. Here, we have investigated the efficiency of ECD versus CID and IRMPD for top-down MS/MS analysis of multiply charged intact nitrated protein ions of myoglobin, lysozyme, and cytochrome c in a commercial Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. CID and IRMPD produced more cleavages in the vicinity of the sites of nitration than ECD. However the total number of ECD fragments was greater than those from CID or IRMPD, and many ECD fragments contained the site(s) of nitration. We conclude that ECD can be used in the top-down analysis of nitrated proteins, but precise localization of the sites of nitration may require either of the “slow-heating” methods. PMID:20677807

  14. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    SciTech Connect

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi-photon

  15. The multiphoton AC Stark effect

    NASA Astrophysics Data System (ADS)

    Rudolph, T. G.; Ficek, Z.; Freedhoff, H. S.

    1998-02-01

    We study the interaction of a two-level atom with two intense lasers: a strong laser of Rabi frequency 2Ω on resonance with the atomic transition, and a weaker laser detuned by 2Ω/n, i.e. by a subharmonic of the Rabi frequency of the first. The second laser "dresses" the dressed states created by the first in an n-photon process. We calculate the energy levels and eigenstates of this "doubly-dressed" atom, and find a new phenomenon: the splitting of the energy levels due to an n-photon coupling between them, resulting in a multiphoton AC Stark effect. We illustrate this effect in the fluorescence spectrum, and show that the spectrum contains triplets at the subharmonic as well as harmonic resonance frequencies with a clear dependence on the order n of the resonance and the ratio α of the Rabi frequencies of the lasers

  16. Differential Multiphoton Laser Scanning Microscopy

    PubMed Central

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

    2016-01-01

    Multifocal multiphoton microscopy (MMM) in the biological and medical sciences has become an important tool for obtaining high resolution images at video rates. While current implementations of MMM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on a method for MMM in which imaging detection is not necessary (single element point detection is implemented), and is therefore fully compatible for use in imaging through scattering media. Further, we demonstrate that this method leads to a new type of MMM wherein it is possible to simultaneously obtain multiple images and view differences in excitation parameters in a single shot. PMID:27390511

  17. Electron Capture Dissociation of Divalent Metal-adducted Sulfated N-Glycans Released from Bovine Thyroid Stimulating Hormone

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Håkansson, Kristina

    2013-11-01

    Sulfated N-glycans released from bovine thyroid stimulating hormone (bTSH) were ionized with the divalent metal cations Ca2+, Mg2+, and Co by electrospray ionization (ESI). These metal-adducted species were subjected to infrared multiphoton dissociation (IRMPD) and electron capture dissociation (ECD) and the corresponding fragmentation patterns were compared. IRMPD generated extensive glycosidic and cross-ring cleavages, but most product ions suffered from sulfonate loss. Internal fragments were also observed, which complicated the spectra. ECD provided complementary structural information compared with IRMPD, and all observed product ions retained the sulfonate group, allowing sulfonate localization. To our knowledge, this work represents the first application of ECD towards metal-adducted sulfated N-glycans released from a glycoprotein. Due to the ability of IRMPD and ECD to provide complementary structural information, the combination of the two strategies is a promising and valuable tool for glycan structural characterization. The influence of different metal ions was also examined. Calcium adducts appeared to be the most promising species because of high sensitivity and ability to provide extensive structural information.

  18. Electron Capture Dissociation of Divalent Metal-adducted Sulfated N-Glycans Released from Bovine Thyroid Stimulating Hormone

    PubMed Central

    Zhou, Wen; Håkansson, Kristina

    2013-01-01

    Sulfated N-glycans released from bovine thyroid stimulating hormone (bTSH) were ionized with the divalent metal cations Ca2+, Mg2+, and Co by electrospray ionization (ESI). These metal-adducted species were subjected to infrared multiphoton dissociation (IRMPD) and electron capture dissociation (ECD) and the corresponding fragmentation patterns were compared. IRMPD generated extensive glycosidic and cross-ring cleavages, but most product ions suffered from sulfonate loss. Internal fragments were also observed, which complicated the spectra. ECD provided complementary structural information compared with IRMPD, and all observed product ions retained the sulfonate group, allowing sulfonate localization. To our knowledge, this work represents the first application of ECD towards metal-adducted sulfated N-glycans released from a glycoprotein. Due to the ability of IRMPD and ECD to provide complementary structural information, the combination of the two strategies is a promising and valuable tool for glycan structural characterization. The influence of different metal ions was also examined. Calcium adducts appeared to be the most promising species because of high sensitivity and ability to provide extensive structural information. PMID:23982932

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

    NASA Astrophysics Data System (ADS)

    Qian, Jun

    2015-03-01

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

  20. Resonance Enhanced Multi-photon Spectroscopy of DNA

    NASA Astrophysics Data System (ADS)

    Ligare, Marshall Robert

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

  1. Multi-photon excitation microscopy

    PubMed Central

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

    2006-01-01

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

  2. Multi-photon excitation microscopy.

    PubMed

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

    2006-01-01

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

  3. Clinical multiphoton and CARS microscopy

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  4. A pragmatic guide to multiphoton microscope design

    PubMed Central

    Young, Michael D.; Field, Jeffrey J.; Sheetz, Kraig E.; Bartels, Randy A.; Squier, Jeff

    2016-01-01

    Multiphoton microscopy has emerged as a ubiquitous tool for studying microscopic structure and function across a broad range of disciplines. As such, the intent of this paper is to present a comprehensive resource for the construction and performance evaluation of a multiphoton microscope that will be understandable to the broad range of scientific fields that presently exploit, or wish to begin exploiting, this powerful technology. With this in mind, we have developed a guide to aid in the design of a multiphoton microscope. We discuss source selection, optical management of dispersion, image-relay systems with scan optics, objective-lens selection, single-element light-collection theory, photon-counting detection, image rendering, and finally, an illustrated guide for building an example microscope. PMID:27182429

  5. Polarization phenomena in multiphoton ionization of atoms

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.

    1973-01-01

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

  6. Multiphoton absorption in amyloid protein fibres

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

    2013-12-01

    Fibrillization of peptides leads to the formation of amyloid fibres, which, when in large aggregates, are responsible for diseases such as Alzheimer's and Parkinson's. Here, we show that amyloids have strong nonlinear optical absorption, which is not present in native non-fibrillized protein. Z-scan and pump-probe experiments indicate that insulin and lysozyme β-amyloids, as well as α-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.

  7. Multiphoton microscopy in defining liver function

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  8. New developments in multimodal clinical multiphoton tomography

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2011-03-01

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

  9. Multiphoton coherent control in complex systems

    PubMed Central

    Goswami, Debabrata

    2005-01-01

    Control of multiphoton transitions is demonstrated for a multilevel system by generalizing the instantaneous phase of any chirped pulse as individual terms of a Taylor series expansion. In the case of a simple two-level system, all odd terms in the series lead to population inversion while the even terms lead to self-induced transparency. The results hold for multiphoton transitions that do not have any lower-order photon resonance or any intermediate virtual state dynamics within the laser pulse width. PMID:17396157

  10. Multiphoton polymerization using optical trap assisted nanopatterning

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  11. Evaluation of the internal temperatures of an 8.6 kDa protein cation exposed to a hot dispenser cathode employed in electron capture dissociation mass spectrometry.

    PubMed

    Yim, Yong-Hyeon; Kim, Byungjoo; Ahn, Seonghee; So, Hun-Young; Lee, Sunyoung; Oh, Han Bin

    2006-01-01

    The 'effective' internal temperature of an 8.6 kDa ubiquitin cation was estimated under electron capture dissociation (ECD) conditions, in which a dispenser cathode electron source was mounted just outside an ion cyclotron resonance (ICR) cell, i.e., axially displaced at a distance less than 1 cm from the rear trap plate of the ICR cell. In this ECD configuration, thermal activation of the molecular ions stored in the ICR cell was anticipated since the heated dispenser cathode (T(cathode surface) > 1000 degrees C) emitted a large amount of (both visible and infrared) radiation as well as electrons. An evaluation of the internal temperature of ubiquitin 6+ and 7+ cations was made by comparing our ECD fragmentation patterns with those obtained by McLafferty et al. (J. Am. Chem. Soc. 2002; 124: 6407) as a function of the ion temperature. In McLafferty's configuration, the heating (or thermal activation) effect of their filament source was minimal since the filament was displaced by a distance as far as 70 cm from their ICR cell. A careful comparison reveals that the fragmentation patterns obtained in this work are very similar to those previously measured at T approximately 125 degrees C. In terms of sequence coverage, our ECD configuration provides better results, and in particular without the aid of any other simultaneous activation method, such as thermal heating, infrared multiphoton irradiation, or collisional activation, except for the visible and infrared radiation from the heated cathode. PMID:16715464

  12. Dissociated Vertical Deviation

    MedlinePlus

    ... Eye Terms Conditions Frequently Asked Questions Español Condiciones Chinese Conditions Dissociated Vertical Deviation En Español Read in Chinese What is Dissociated Vertical Deviation (DVD)? DVD is ...

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  14. RAIRS observation of photoinduced dissociation of NO on Ni(111)

    NASA Astrophysics Data System (ADS)

    Magkoev, Tamerlan T.; Song, Moon-Bong; Fukutani, Katsuyuki; Murata, Yoshitada

    1995-06-01

    The properties of the {NO}/{Ni(111) } system under nanosecond ultraviolet laser light irradiation are studied by reflection absorption infrared spectroscopy. It is found that adsorbed NO molecules are dissociated by laser light. Dissociation proceeds effectively in a dilute NO layer, whereas it is suppressed in a saturated overlayer.

  15. Formalism for multiphoton plasmon excitation in jellium clusters

    NASA Astrophysics Data System (ADS)

    Connerade, Jean-Patrick; Solov'yov, Andrey V.

    2002-07-01

    We present a formalism for the description of multiphoton plasmon excitation processes in jellium clusters. By using our method, we demonstrate that, in addition to dipole plasmon excitations, the multipole plasmons (quadrupole, octupole, etc.) can be excited in a cluster by multiphoton absorption processes, which results in a significant difference between plasmon resonance profiles in the cross sections for multiphoton as compared to single-photon absorption. We calculate the cross sections for multiphoton absorption and analyze the balance between the surface and volume plasmon contributions to multipole plasmons.

  16. Multiphoton Microscopy for Visualizing Lipids in Tissue.

    PubMed

    Lee, Martin; Serrels, Alan

    2016-01-01

    Visualizing the appearance of fat droplets and adipocytes in tissue can be realized using a label-free imaging method known as coherent anti-Stokes Raman spectroscopy (CARS). CARS is a nonlinear optical technique that allows label-free imaging of a material with contrast based on the same vibrational signatures of molecules found in Raman spectroscopy. CARS can be combined with other single and multiphoton imaging modes such as second harmonic generation and two-photon fluorescence to image a broad variety of biological structures.Here we describe the construction of a multiphoton microscope that will enable the study of both fluorescently labeled and unlabeled tissue. This has been used to monitor the contribution of Wt1 expressing cells towards the visceral fat depots during gestation. PMID:27417963

  17. Clinical multiphoton endoscopy with FLIM capability

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    Multiphoton endoscopy can be applied for intra-corporeal imaging as well as to examine otherwise hard-to-access tissue areas like chronic wounds. Using high-NA (NA = 0.8) gradient-index (GRIN) lens-based endoscopes with a diameter of 1.4 mm and effective lengths of 7 mm and 20 mm, respectively, two-photon excitation of endogenous fluorophores and second-harmonic generation (SHG) is used for multimodal in vivo imaging of human skin. A further imaging modality is fluorescence lifetime imaging (FLIM) which allows functional imaging to investigate the healing mechanism of chronic wounds and the corresponding cell metabolism. We performed first in vivo measurements using FLIM endoscopy with the medically-certified multiphoton tomograph MPTflex® in combination with a computer-controlled motorized scan head and a GRIN-lens endoscope.

  18. Multiphoton tomography of intratissue tattoo nanoparticles

    NASA Astrophysics Data System (ADS)

    König, Karsten

    2012-02-01

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

  19. Multiphoton Microwave Ionization of Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Gurian, Joshua Houston

    This thesis describes a series of multiphoton microwave experiments on Rydberg atoms when the microwave frequency is much greater than the classical Kepler frequency of the excited atoms. A new kHz pulse repetition frequency dye laser system was constructed for Rydberg lithium excitation with a linewidth as narrow as 3 GHz. This new laser system is used for first experiments of multiphoton microwave ionization of Rydberg lithium approaching the photoionization limit using 17 and 36 GHz microwave pulses. A multi-channel quantum defect model is presented that well describes the experimental results, indicating that these results are due to the coherent coupling of many atomic levels both above and below the classical ionization limit. Finally, preliminary results of measuring the final-state distributions of high lying Rydberg states after 17 GHz microwave pulses are presented.

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

    PubMed Central

    Seemann, K.M.; Kuhn, B.

    2014-01-01

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

  1. First multiphoton tomography of brain in man

    NASA Astrophysics Data System (ADS)

    König, Karsten; Kantelhardt, Sven R.; Kalasauskas, Darius; Kim, Ella; Giese, Alf

    2016-03-01

    We report on the first two-photon in vivo brain tissue imaging study in man. High resolution in vivo histology by multiphoton tomography (MPT) including two-photon FLIM was performed in the operation theatre during neurosurgery to evaluate the feasibility to detect label-free tumor borders with subcellular resolution. This feasibility study demonstrates, that MPT has the potential to identify tumor borders on a cellular level in nearly real-time.

  2. Medium-induced multi-photon radiation

    NASA Astrophysics Data System (ADS)

    Ma, Hao; Salgado, Carlos A.; Tywoniuk, Konrad

    2011-01-01

    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 Molière limit. We find that in this limit the LPM effect holds for medium-induced two-photon ladder emission.

  3. Fundamental studies of molecular multiphoton ionization

    SciTech Connect

    Miller, J.C.; Compton, R.N.

    1984-04-01

    For several years the authors have performed fundamental studies of molecular multiphoton ionization (MPI). We will present a potpourri of techniques and results chosen to illustrate the interesting complexities of molecular MPI. Techniques used include time-of-flight mass spectroscopy, photoelectron spectroscopy, supersonic expansion cooling of molecular beams, harmonic generation, two-color laser MPI, and polarization spectroscopy. Whenever possible the relevance of these results to resonance ionization spectroscopy schemes will be delineated. 23 references, 10 figures.

  4. Video-rate resonant scanning multiphoton microscopy

    PubMed Central

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

    2013-01-01

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

  5. Multiphoton harvesting metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Quah, Hong Sheng; Chen, Weiqiang; Schreyer, Martin K.; Yang, Hui; Wong, Ming Wah; Ji, Wei; Vittal, Jagadese J.

    2015-08-01

    Multiphoton upconversion is a process where two or more photons are absorbed simultaneously to excite an electron to an excited state and, subsequently, the relaxation of electron gives rise to the emission of a photon with frequency greater than those of the absorbed photons. Materials possessing such property attracted attention due to applications in biological imaging, photodynamic therapy, three-dimensional optical data storage, frequency-upconverted lasing and optical power limiting. Here we report four-photon upconversion in metal-organic frameworks containing the ligand, trans, trans-9,10-bis(4-pyridylethenyl)anthracene. The ligand has a symmetrical acceptor-π-donor-π-acceptor structure and a singlet biradical electronic ground state, which boosted its multiphoton absorption cross-sections. We demonstrate that the upconversion efficiency can be enhanced by Förster resonance energy transfer within host-guest metal-organic frameworks consisting of encapsulated high quantum yielding guest molecules. Using these strategies, metal-organic framework materials, which can exhibit frequency-upconverted photoluminescence excited by simultaneous multiphoton absorption, can be rationally designed and synthesized.

  6. Multiphoton harvesting metal–organic frameworks

    PubMed Central

    Quah, Hong Sheng; Chen, Weiqiang; Schreyer, Martin K.; Yang, Hui; Wong, Ming Wah; Ji, Wei; Vittal, Jagadese J.

    2015-01-01

    Multiphoton upconversion is a process where two or more photons are absorbed simultaneously to excite an electron to an excited state and, subsequently, the relaxation of electron gives rise to the emission of a photon with frequency greater than those of the absorbed photons. Materials possessing such property attracted attention due to applications in biological imaging, photodynamic therapy, three-dimensional optical data storage, frequency-upconverted lasing and optical power limiting. Here we report four-photon upconversion in metal–organic frameworks containing the ligand, trans, trans-9,10-bis(4-pyridylethenyl)anthracene. The ligand has a symmetrical acceptor–π–donor–π–acceptor structure and a singlet biradical electronic ground state, which boosted its multiphoton absorption cross-sections. We demonstrate that the upconversion efficiency can be enhanced by Förster resonance energy transfer within host–guest metal–organic frameworks consisting of encapsulated high quantum yielding guest molecules. Using these strategies, metal–organic framework materials, which can exhibit frequency-upconverted photoluminescence excited by simultaneous multiphoton absorption, can be rationally designed and synthesized. PMID:26245741

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  8. Waveguide-integrated single- and multi-photon detection at telecom wavelengths using superconducting nanowires

    SciTech Connect

    Ferrari, Simone; Kahl, Oliver; Kovalyuk, Vadim; Goltsman, Gregory N.; Korneev, Alexander; Pernice, Wolfram H. P.

    2015-04-13

    We investigate single- and multi-photon detection regimes of superconducting nanowire detectors embedded in silicon nitride nanophotonic circuits. At near-infrared wavelengths, simultaneous detection of up to three photons is observed for 120 nm wide nanowires biased far from the critical current, while narrow nanowires below 100 nm provide efficient single photon detection. A theoretical model is proposed to determine the different detection regimes and to calculate the corresponding internal quantum efficiency. The predicted saturation of the internal quantum efficiency in the single photon regime agrees well with plateau behavior observed at high bias currents.

  9. Nonlinear effects in infrared action spectroscopy of silicon and vanadium oxide clusters: experiment and kinetic modeling.

    PubMed

    Calvo, Florent; Li, Yejun; Kiawi, Denis M; Bakker, Joost M; Parneix, Pascal; Janssens, Ewald

    2015-10-21

    For structural assignment of gas phase compounds, infrared action spectra are usually compared to computed linear absorption spectra. However, action spectroscopy is highly nonlinear owing to the necessary transfer of the excitation energy and its subsequent redistribution leading to statistical ionization or dissociation. Here, we examine by joint experiment and dedicated modeling how such nonlinear effects affect the spectroscopic features in the case of selected inorganic clusters. Vibrational spectra of neutral silicon clusters are recorded by tunable IR-UV two-color ionization while IR spectra for cationic vanadium oxide clusters are obtained by IR multiphoton absorption followed by dissociation of the bare cluster or of its complex with Xe. Our kinetic modeling accounts for vibrational anharmonicities, for the laser interaction through photon absorption and stimulated emission rates, as well as for the relevant ionization or dissociation rates, all based on input parameters from quantum chemical calculations. Comparison of the measured and calculated spectra indicates an overall agreement as far as trends are concerned, except for the photodissociation of the V3O7(+)-Xe messenger complex, for which anharmonicities are too large and poorly captured by the perturbative anharmonic model. In all systems studied, nonlinear effects are essentially manifested by variations in the intensities as well as spectral broadenings. Differences in some band positions originate from inaccuracies of the quantum chemical data rather than specific nonlinear effects. The simulations further yield information on the average number of photons absorbed, which is otherwise unaccessible information: several to several tens of photons need to be absorbed to observe a band through dissociation, while three to five photons can be sufficient for detection of a band via IR-UV ionization. PMID:26208251

  10. Some simple mechanisms of multiphoton excitation in many - level systems

    NASA Astrophysics Data System (ADS)

    Donley, E. A.; Marquardt, R.; Quack, M.; Stohner, J.; Thanopulos, I.; Wallenborn, E.-U.

    Results are reported on coherent monochromatic multiphoton excitation in many-level systems, which are representative for some of the basic mechanisms for atomic and molecular multiphoton processes. Numerical solutions are discussed that use the Floquet and quasiresonant approximations in the framework of the URIMIR program package. The excitation schemes include direct three-photon excitation, two-photon excitation with diagonal coupling, Göppert-Mayer-type two-photon processes, multiphoton excitation with off-resonant intermediates, and practically irreversible coherent excitation into dense spectral structures. Several interesting phenomena are observed, such as nonlinear line shifts and broadenings of multiphoton resonances of relevance for multiphoton spectroscopy and almost constant intermediate population inversions, potentially useful for laser design. The accurate numerical results are compared with approximate solutions from perturbation theory, and with simple analytical solutions from Rabi-type formulae.

  11. The dissociative bond.

    PubMed

    Gordon, Nirit

    2013-01-01

    Dissociation leaves a psychic void and a lingering sense of psychic absence. How do 2 people bond while they are both suffering from dissociation? The author explores the notion of a dissociative bond that occurs in the aftermath of trauma--a bond that holds at its core an understanding and shared detachment from the self. Such a bond is confined to unspoken terms that are established in the relational unconscious. The author proposes understanding the dissociative bond as a transitional space that may not lead to full integration of dissociated knowledge yet offers some healing. This is exemplified by R. Prince's (2009) clinical case study. A relational perspective is adopted, focusing on the intersubjective aspects of a dyadic relationship. In the dissociative bond, recognition of the need to experience mutual dissociation can accommodate a psychic state that yearns for relationship when the psyche cannot fully confront past wounds. Such a bond speaks to the need to reestablish a sense of human relatedness and connection when both parties in the relationship suffer from disconnection. This bond is bound to a silence that becomes both a means of protection against the horror of traumatic memory and a way to convey unspoken gestures toward the other. PMID:23282044

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2000-12-01

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

  14. Multi-photon processes in alkali metal vapors

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  15. Pulse front adaptive optics in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  16. Polymer microcantilevers fabricated via multiphoton absorption polymerization

    NASA Astrophysics Data System (ADS)

    Bayindir, Z.; Sun, Y.; Naughton, M. J.; LaFratta, C. N.; Baldacchini, T.; Fourkas, J. T.; Stewart, J.; Saleh, B. E. A.; Teich, M. C.

    2005-02-01

    We have used multiphoton absorption polymerization to fabricate a series of microscale polymer cantilevers. Atomic force microscopy has been used to characterize the mechanical properties of microcantilevers with spring constants that were found to span more than four decades. From these data, we extracted a Young's modulus of E =0.44GPa for these microscale cantilevers. The wide stiffness range and relatively low elastic modulus of the microstructures make them attractive candidates for a range of microcantilever applications, including measurements on soft matter.

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

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

  18. Widefield multiphoton excited fluorescence microscopy for animal study in vivo

    NASA Astrophysics Data System (ADS)

    Cheng, L.-C.; Chang, C.-Y.; Lin, C.-H.; Su, Y.-D.; Huang, T.-Y.; Chen, S.-J.

    2010-08-01

    Unlike conventional multiphoton excited microscopy according to pixel-by-pixel point scanning, a widefield multiphoton excited microscopy based on spatiotemporal focusing has been developed to construct three-dimensional (3D) multiphoton fluorescence images only with the need of an axial scanning. By implementing a 4.0 W 10 kHz femtosecond laser amplifier with an instant strong peak power and a fast TE-cooled EMCCD camera with an ultra-sensitive fluorescence detection, the multiphoton excited fluorescence images with the excitation area over 100 μm x 100 μm can be achieved at a frame rate up to 80 Hz. A mechanical shutter is utilized to control the exposure time of 1 ms, i.e. average ten laser pulses reach the fluorescent specimen, and hence an uniform enough multiphoton excited fluorescence image can be attained with less photobleaching. The Brownian motion of microbeads and 3D neuron cells of a rat cerebellum have been observed with a lateral spatial resolution of 0.24 μm and an axial resolution of 2.5 μm. Therefore, the developed widefield multiphoton microscopy can provide fast and high-resolution multiphoton excited fluorescence images for animal study in vivo.

  19. Multiphoton imaging with a nanosecond supercontinuum source

    NASA Astrophysics Data System (ADS)

    Lefort, Claire; O'Connor, Rodney P.; Blanquet, Véronique; Baraige, Fabienne; Tombelaine, Vincent; Lévêque, Philippe; Couderc, Vincent; Leproux, Philippe

    2016-03-01

    Multiphoton microscopy is a well-established technique for biological imaging of several kinds of targets. It is classically based on multiphoton processes allowing two means of contrast simultaneously: two-photon fluorescence (TPF) and second harmonic generation (SHG). Today, the quasi exclusive laser technology used in that aim is femtosecond titanium sapphire (Ti: Sa) laser. We experimentally demonstrate that a nanosecond supercontinuum laser source (STM-250-VIS-IR-custom, Leukos, France; 1 ns, 600-2400 nm, 250 kHz, 1 W) allows to obtain the same kind of image quality in the case of both TPF and SHG, since it is properly filtered. The first set of images concerns the muscle of a mouse. It highlights the simultaneous detection of TPF and SHG. TPF is obtained thanks to the labelling of alpha-actinin with Alexa Fluor® 546 by immunochemistry. SHG is created from the non-centrosymmetric organization of myosin. As expected, discs of actin and myosin are superimposed alternatively. The resulting images are compared with those obtained from a standard femtosecond Ti: Sa source. The physical parameters of the supercontinuum are discussed. Finally, all the interest of using an ultra-broadband source is presented with images obtained in vivo on the brain of a mouse where tumor cells labeled with eGFP are grafted. Texas Red® conjugating Dextran is injected into the blood vessels network. Thus, two fluorophores having absorption wavelengths separated by 80 nm are imaged simultaneously with a single laser source.

  20. Multimodal optoacoustic and multiphoton fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Sela, Gali; Razansky, Daniel; Shoham, Shy

    2013-03-01

    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.

  1. Development of an applicator for multiphoton PDT

    NASA Astrophysics Data System (ADS)

    Graschew, Georgi; Bastian, Matthias; Rakowsky, Stefan; Roelofs, Theo A.; Balanos, Evangelos; Schlag, Peter M.; Steinmeyer, Gunter; Elsaesser, Thomas

    2004-09-01

    Multiphoton excitation of photosensitizers for laser induced fluorescence diagnosis (LIFD) and photodynamic therapy (PDT) of tumors has the advantage of greater tissue penetration due to the longer wavelength of irradiation. However, multiphoton LIFD and PDT are presently not clinically applicable as there are no applicators available for the delivery of the pulsed laser radiation to the operating room. As an approach, in this contribution the beam delivery through photonic crystal fibers has been investigated. Pulses of a Ti:sapphire laser of 100 fs pulse duration and an average power of 150 mW have been transported through such a fiber of 25 m length and the resulting pulses show the absence of nonlinear contributions but still a broadening of the pulse to 2 ps due to the dispersion of the fiber. It is planned to compensate this broadening by a grating in front of the fiber. Alternatively, the transport of laser radiation of 150 fs and 100 mW through a mirror-joint-arm used for conventional CO2 lasers has been tested showing no broadening of the laser pulses. Two-photon photodynamic activity of mTHPC-CMPEG4 shall serve as a test of the laser light transport system.

  2. Multiphoton ionization of large water clusters

    SciTech Connect

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

    2014-05-28

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

  3. Dissociation of diatomic gases

    NASA Technical Reports Server (NTRS)

    Hansen, C. F.

    1991-01-01

    The Landau-Zener theory of reactive cross sections has been applied to diatomic molecules dissociating from a ladder of rotational and vibrational states. Although the preexponential factor of the Arrhenius rate expression is shown to be a complex function of the dimensionless activation energy, the average over all states in the ladder is well represented by a single factor that varies about as T exp (-n), where the coefficient n is the order of unity. This relation agrees very well with experimental data for dissociation of O2 and N2, for example. The results validate previous empirical assignment of a single preexponential factor in the Arrhenius expression and justify the extrapolation of the expression well beyond the range of data. The theory is then used to calculate the effect of vibrational nonequilibrium on dissociation rate. For Morse oscillators the results are about the same as for harmonic oscillators, and the dissociation from a ladder of equilibrium rotational and nonequilibrium vibrational states is close to an analytic approximation provided by Hammerling, Kivel, and Teare for harmonic oscillators all dissociating from the ground rotational state.

  4. Multiphoton imaging of biological samples during freezing and heating

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    We applied multiphoton microscopic imaging to observe freezing and heating effects in plant- and animal cell samples. The experimental setups consisted of a multiphoton imaging system and a heating and cooling stage which allows for precise temperature control from liquid nitrogen temperature (-196°C 77 K) up to +600°C (873 K) with heating/freezing rates between 0.01 K/min and 150 K/min. Two multiphoton imaging systems were used: a system based on a modified optical microscope and a flexible mobile system. To illustrate the imaging capabilities, plant leafs as well as animal cells were microscopically imaged in vivo during freezing based on autofluorescence lifetime and intensity of intrinsic molecules. The measurements illustrate the usefulness of multiphoton imaging to investigate freezing effects on animal and plant cells.

  5. REVIEW ARTICLE Multiphoton polymerization of hybrid materials

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  6. Multiphoton microscopy of cleared mouse organs

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Typical imaging depths with multiphoton microscopy (MPM) are limited to less than 300 μm 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.

  7. Enhancing Multiphoton Rates with Quantum Memories

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  8. Point spread function engineering with multiphoton SPIFI

    NASA Astrophysics Data System (ADS)

    Wernsing, Keith A.; Field, Jeffrey J.; Domingue, Scott R.; Allende-Motz, Alyssa M.; DeLuca, Keith F.; Levi, Dean H.; DeLuca, Jennifer G.; Young, Michael D.; Squier, Jeff A.; Bartels, Randy A.

    2016-03-01

    MultiPhoton SPatIal Frequency modulated Imaging (MP-SPIFI) has recently demonstrated the ability to simultaneously obtain super-resolved images in both coherent and incoherent scattering processes -- namely, second harmonic generation and two-photon fluorescence, respectively.1 In our previous analysis, we considered image formation produced by the zero and first diffracted orders from the SPIFI modulator. However, the modulator is a binary amplitude mask, and therefore produces multiple diffracted orders. In this work, we extend our analysis to image formation in the presence of higher diffracted orders. We find that tuning the mask duty cycle offers a measure of control over the shape of super-resolved point spread functions in an MP-SPIFI microscope.

  9. Multiphoton imaging with high peak power VECSELs

    NASA Astrophysics Data System (ADS)

    Mirkhanov, Shamil; Quarterman, Adrian H.; Swift, Samuel; Praveen, Bavishna B.; Smyth, Conor J. C.; Wilcox, Keith G.

    2016-03-01

    Multiphoton imaging (MMPI) has become one of thee key non-invasive light microscopy techniques. This technique allows deep tissue imaging with high resolution and less photo-damage than conventional confocal microscopy. MPI is type of laser-scanning microscopy that employs localized nonlinear excitation, so that fluorescence is excited only with is scanned focal volume. For many years, Ti: sapphire femtosecond lasers have been the leading light sources for MPI applications. However, recent developments in laser sources and new types of fluorophores indicate that longer wavelength excitation could be a good alternative for these applications. Mode-locked VECSEELs have the potential to be low cost, compact light sources for MPI systems, with the additional advantage of broad wavelength coverage through use of different semiconductor material systems. Here, we use a femtosecond fibber laser to investigate the effect average power and repetition rate has on MPI image quality, to allow us to optimize our mode-locked VVECSELs for MPI.

  10. Multi-photon entanglement in high dimensions

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Forming the backbone of quantum technologies today, entanglement has been demonstrated in physical systems as diverse as photons, ions and superconducting circuits. Although steadily pushing the boundary of the number of particles entangled, these experiments have remained in a two-dimensional space for each particle. Here we show the experimental generation of the first multi-photon entangled state where both the number of particles and dimensions are greater than two. Two photons in our state reside in a three-dimensional space, whereas the third lives in two dimensions. This asymmetric entanglement structure only appears in multiparticle entangled states with d > 2. Our method relies on combining two pairs of photons, high-dimensionally entangled in their orbital angular momentum. In addition, we show how this state enables a new type of ‘layered’ quantum communication protocol. Entangled states such as these serve as a manifestation of the complex dance of correlations that can exist within quantum mechanics.

  11. Multiphoton double ionization of the He atom

    NASA Astrophysics Data System (ADS)

    Li, Y.; Pindzola, M. S.

    2016-05-01

    Time-dependent close-coupling (TDCC) calculations are made for the multiphoton double ionization of the He atom under the influence of a fast pulse XUV laser. One set of TDCC calculations employs l1m1l2m2 coupling on a 2D (r1 ,r2) numerical lattice, a second set of TDCC calculations employs m1m2 coupling on a 4D (r1 ,θ1 ,r2 ,θ2) numerical lattice, and a third set of TDCC calculations employs m1m2 coupling on a 4D (ρ1 ,z1 ,ρ2 ,z2) numerical lattice. Studies are made to see which TDCC method is the most efficient at explaining measurements as the number of photons absorbed is increased. Work supported in part by Grants from NASA, NSF, and DOE.

  12. Nonlinear magic: multiphoton microscopy in the biosciences.

    PubMed

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

    2003-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  14. Dissociative Reactions to Incest.

    ERIC Educational Resources Information Center

    Hall, J. Mark

    In contrast to Freud's later and revised view of the etiology of hysterical, or dissociative, symptoms, it is now known that real, and not fantasized, sexual experiences in childhood are experienced in disociative symptomatology. It is useful to understand that incest involves both traumatic events, that is, incidents of sexual violation per se,…

  15. Dissociative Identity Disorder

    ERIC Educational Resources Information Center

    Schmidt, Tom

    2007-01-01

    Few psychological disorders in the Diagnostic Statistical Manual have generated as much controversy as Dissociative Identity Disorder (DID). For the past 35 years diagnoses of DID, previously referred to as Multiple Personality Disorder (MPD), have increased exponentially, causing various psychological researchers and clinicians to question the…

  16. Dissociation and psychosis in dissociative identity disorder and schizophrenia.

    PubMed

    Laddis, Andreas; Dell, Paul F

    2012-01-01

    Dissociative symptoms, first-rank symptoms of schizophrenia, and delusions were assessed in 40 schizophrenia patients and 40 dissociative identity disorder (DID) patients with the Multidimensional Inventory of Dissociation (MID). Schizophrenia patients were diagnosed with the Structured Clinical Interview for the DSM-IV Axis I Disorders; DID patients were diagnosed with the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised. DID patients obtained significantly (a) higher dissociation scores; (b) higher passive-influence scores (first-rank symptoms); and (c) higher scores on scales that measure child voices, angry voices, persecutory voices, voices arguing, and voices commenting. Schizophrenia patients obtained significantly higher delusion scores than did DID patients. What is odd is that the dissociation scores of schizophrenia patients were unrelated to their reports of childhood maltreatment. Multiple regression analyses indicated that 81% of the variance in DID patients' dissociation scores was predicted by the MID's Ego-Alien Experiences Scale, whereas 92% of the variance in schizophrenia patients' dissociation scores was predicted by the MID's Voices Scale. We propose that schizophrenia patients' responses to the MID do not index the same pathology as do the responses of DID patients. We argue that neither phenomenological definitions of dissociation nor the current generation of dissociation instruments (which are uniformly phenomenological in nature) can distinguish between the dissociative phenomena of DID and what we suspect are just the dissociation-like phenomena of schizophrenia. PMID:22651674

  17. Pathological Dissociation as Measured by the Child Dissociative Checklist

    ERIC Educational Resources Information Center

    Wherry, Jeffrey N.; Neil, Debra A.; Taylor, Tamara N.

    2009-01-01

    The component structure of the Child Dissociative Checklist was examined among abused children. A factor described as pathological dissociation emerged that was predicted by participants being male. There also were differences in pathological dissociation between groups of sexually abused and physically abused children. Replication of this factor…

  18. Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

    SciTech Connect

    Borglin, Johan; Guldbrand, Stina; Evenbratt, Hanne; Kirejev, Vladimir; Ericson, Marica B.; Grönbeck, Henrik

    2015-12-07

    Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.

  19. Development of a portable multiphoton photo-acoustic spectroscopy system for tumor diagnostics

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    In this paper we describe the development of a novel fiber optic probe for subsurface tumor diagnostics, based on non-resonant multiphoton photoacoustic spectroscopy (NMPPAS). In this technique, endogenous biomarkers present in tissues are irradiated in the near infrared, using a tunable high-power laser. The resulting multiphoton excitation events are detected as an acoustic (i.e. ultrasonic) signal, using an ultrasonic piezoelectric transducer. The signal from the piezoelectric transducer is then corrected for laser power fluctuations by normalizing the NMPPAS signal at each wavelength with the laser intensity recorded, from an optical diode. By scanning the laser excitation over the appropriate wavelength range for the tissue of interest, absorption differences between normal and tumor tissues can be measured and analyzed. The fiber optic probe was characterized and optimized for transmission efficiency as well as its time dependent response to high power laser pulses. The focusing optics were optimized and a piezoelectric transducer film detector chosen based on its sensitivity in the ultrasonic frequency range of interest. Using this probe system NMPPAS measurements were performed on several common fluorescent dyes including rhodamine 6G as well as well-characterized biomarkers like tryptophan. Furthermore, the technique was further successfully applied to the differentiation of tumorous and healthy human brain tissues.

  20. Evidence for excitation of fluorescence in RPE melanin by multiphoton absorption

    NASA Astrophysics Data System (ADS)

    Glickman, Randolph D.; Rockwell, Benjamin A.; Noojin, Gary D.; Stolarski, David J.; Denton, Michael L.

    2002-06-01

    Previously, we reported that ultrashort, near infrared (NIR) laser pulses caused more DNA breakage in cultured retinal pigment epithelial (RPE) cells than did CW, NIR laser radiation delivering a similar radiant exposure. We hypothesized that this difference was due to multiphoton absorption in an intracellular chromophore such as the RPE melanin. We investigated two-photon excitation of fluorescence in a suspension of isolated bovine RPE melanosomes exposed to a 1-KHz train of approximately 50- fsec laser pulses at 810 nm from a Ti:Sapphire laser, and compared this to the fluorescence excited by CW exposures at 406 nm from a Krypton ion laser. Fluorescence was measured with a PC-based spectrometer. The CW sources excited fluorescence with a peak at 525 nm. The fluorescence intensity depended on the irradiance of the sample, as well as the melanosome concentration. Peak fluorescence was obtained with a suspension of ~2 x 107 melanin granules/ml. The 810-nm, ultrashort pulses also excited fluorescence, but with a broader, lower-amplitude peak. The weaker fluorescence signal excited by the 810-nm ultrashort pulse laser for a given melanosome concentration, compared to 406-nm CW excitation, is possibly due to the smaller two- photon absorption cross-section. These results indicate the involvement of multiphoton absorption in DNA damage.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  4. Preparation of metallo-dielectric photonic crystals by multi-photon direct laser writing

    NASA Astrophysics Data System (ADS)

    Kuebler, Stephen M.; Tal, Amir; Chen, Yun-Sheng

    2008-02-01

    Metallo-dielectric photonic crystals (MDPCs) can exhibit intriguing and potentially useful optical properties, including ultra-wide photonic bandgaps, engineered thermal emission, and negative refractive index. But access to such materials has been limited by the lack of suitable methods for their preparation. We have developed a route to three-dimensional (3D) MDPCs that involves fabricating a polymeric pre-form by multi-photon direct laser writing and then conformally depositing metal onto the pre-form by electroless metallization. We use the approach to prepare silver- and copper-plated "woodpile" PCs having face-centered tetragonal symmetry and unit-cell period of several micrometers. The resulting 3D metallized structures exhibit mid-infrared reflectance that is consistent with theory and experimental observations obtained for MDPCs prepared by other routes. These data indicate that multi-photon direct laser writing coupled with electroless metallization is a viable route to complex 3D MDPCs of many symmetries and basis sets and provides a path for integrating such structures with other micron-scale optical elements.

  5. Measurements of serotonin and related indoles using capillary electrophoresis with multiphoton-induced hyperluminescence.

    PubMed

    Gostkowski, M L; Wei, J; Shear, J B

    1998-07-01

    We report the use of multiphoton-excited photochemistry to generate highly fluorescent products from hydroxyindoles fractionated in submicron capillary electrophoresis channels. In this approach, the near-infrared (750 nm) output from a modelocked titanium:sapphire laser is focused at the outlet of a 0.6-micron i.d. capillary, producing pulse intensities of approximately 10(12) W cm-2 within a femtoliter focal volume. Hydroxyindole molecules migrating through the outlet aperture of the capillary intersect the beam focus, where absorption of three to four photons (approximately 1.65 eV photon-1) initiates a photobleaching reaction. The resultant hydroxyindole photoproducts produce broadband visible emission (lambdamax approximately 500 nm) when excited with two additional near-IR photons and appear substantially more resistant to photobleaching than the parent hydroxyindoles. This multiphoton-induced conversion of analytes to hyperluminescent derivatives thus offers a more sensitive approach than UV fluorescence for detecting extremely small quantities of material. Mixtures of the hydroxyindoles serotonin (5-hydroxytryptamine), 5-hydroxytryptophan, and 5-hydroxyindole acetic acid are reliably characterized (relative error approximately 10%) in 100 s, with detection limits as low as approximately 70 zmol (approximately 42,000 molecules). The sensitivity of this measurement strategy improves on the best previously reported results for capillary separations of indoles by more than one order of magnitude. PMID:9657885

  6. 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)

    Glickman, Randolph D.; Johnson, Thomas E.

    2004-07-01

    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.

  7. Three dimensions of dissociative amnesia.

    PubMed

    Dell, Paul F

    2013-01-01

    Principal axis factor analysis with promax rotation extracted 3 factors from the 42 memory and amnesia items of the Multidimensional Inventory of Dissociation (MID) database (N = 2,569): Discovering Dissociated Actions, Lapses of Recent Memory and Skills, and Gaps in Remote Memory. The 3 factors' shared variance ranged from 36% to 64%. Construed as scales, the 3 factor scales had Cronbach's alpha coefficients of .96, .94, and .93, respectively. The scales correlated strongly with mean Dissociative Experiences Scale scores, mean MID scores, and total scores on the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised (SCID-D-R). What is interesting is that the 3 amnesia factors exhibited a range of correlations with SCID-D-R Amnesia scores (.52, .63, and .70, respectively), suggesting that the SCID-D-R Amnesia score emphasizes gaps in remote memory over amnesias related to dissociative identity disorder. The 3 amnesia factor scales exhibited a clinically meaningful pattern of significant differences among dissociative identity disorder, dissociative disorder not otherwise specified-1, dissociative amnesia, depersonalization disorder, and nonclinical participants. The 3 amnesia factors may have greater clinical utility for frontline clinicians than (a) amnesia as discussed in the context of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, nosology of the dissociative disorders or (b) P. Janet's (1893/1977 ) 4-fold classification of dissociative amnesia. The author recommends systematic study of the phenomenological differences within specific dissociative symptoms and their differential relationship to specific dissociative disorders. PMID:23282045

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

    SciTech Connect

    Marcos Dantus

    2008-09-23

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

  9. Dissociative ionization of sodium molecules via repulsive Rydberg states

    NASA Astrophysics Data System (ADS)

    Chen, Hong

    In this thesis, an investigation of two color resonance multiphoton ionization (REMPI) and fragmentation processes in Na2 has been performed in combination with Linear Time-of-Flight Mass Spectrometry technique. The ionization and dissociative ionizations channels in the energy range up to 2500cm -1 above the dissociative ionization threshold into Na(3s)+Na ++e have been studied. After a mild supersonic expansion from the beam source, neutral sodium dimers in the ground state have been produced. Two tunable, pulsed lasers excite Na2 molecules via the intermediate A1S+u state to a single ro-vibrational level of the second intermediate 21pig state. Following absorption of a third photon, the total energy is above the dissociation limit into Na(3s) + Na+ + e. Typically, a small portion of atomic ions is produced under our experimental conditions. By varying the total available energy below and through the doubly excited states correlating with the Na(3p)+Na(4s) atom pair, there is no evidence that the doubly excited states positioned in the ionic continuum get involved. By calculation of the expected transition probabilities for all possible channels which can decay directly and indirectly into atomic ions, I find that direct dissociative ionization via 12S+u is impossible. The transition probabilities for dissociative ionization via the repulsive Rydberg states with principal quantum numbers n from 5˜12 converging toward the 12S+u state are three to four orders of magnitude larger than those for direct ionization into the continuum of the X2S+g ground state. These repulsive Rydberg states are much more likely to play a role in the photo-ionization through the intermediate 21Pg state. A semi-classical model which was originally developed for negative ion dissociative attachment (O'MAL'67) describes how dissociative ionization occurs along the repulsive Rydberg states. Its prediction concerning the ratio of atomic to molecular ion production as a function of initial

  10. Dissociation and psychotic symptoms.

    PubMed

    Steingard, S; Frankel, F H

    1985-08-01

    The literature on hysterical or brief reactive psychosis reflects great diversity both in clinical description and theoretical formulation. The authors describe the case of a 17-year-old girl who presented with a diagnosis of bipolar affective disorder, rapid cycling type, but who, in fact, was experiencing dissociative episodes manifested as psychotic states. The patient's successful treatment with hypnosis is described, along with the clinical and theoretical implications of the case. PMID:4025593

  11. The multiphoton ionization of uranium hexafluoride

    SciTech Connect

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

    1992-05-01

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

  12. Multiphoton excitation of fluorescent DNA base analogs

    NASA Astrophysics Data System (ADS)

    Katilius, Evaldas; Woodbury, Neal W.

    2006-07-01

    Multiphoton excitation was used to investigate properties of the fluorescent DNA base analogs, 2-aminopurine (2AP) and 6-methylisoxanthopterin (6MI). 2-aminopurine, a fluorescent analog of adenine, was excited by three-photon absorption. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2AP for DNA-protein interaction studies. However, high excitation power and long integration times needed to acquire high signal-to-noise fluorescence correlation curves render three-photon excitation FCS of 2AP not very useful for studying DNA base dynamics. The fluorescence properties of 6-methylisoxanthopterin, a guanine analog, were investigated using two-photon excitation. The two-photon absorption cross-section of 6MI was estimated to be about 2.5×10-50 cm4s (2.5 GM units) at 700 nm. The two-photon excitation spectrum was measured in the spectral region from 700 to 780 nm; in this region the shape of the two-photon excitation spectrum is very similar to the shape of single-photon excitation spectrum in the near-UV spectral region. Two-photon excitation of 6MI is suitable for fluorescence correlation measurements. Such measurements can be used to study DNA base dynamics and DNA-protein interactions over a broad range of time scales.

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

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Gu, Zetong; DiMarzio, Charles

    2015-02-01

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

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

    PubMed

    König, K

    2000-08-01

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

  15. Multiphoton photoemission from a copper cathode illuminated by ultrashort laser pulses in an RF photoinjector.

    PubMed

    Musumeci, P; Cultrera, L; Ferrario, M; Filippetto, D; Gatti, G; Gutierrez, M S; Moody, J T; Moore, N; Rosenzweig, J B; Scoby, C M; Travish, G; Vicario, C

    2010-02-26

    In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount of electrons by a copper cathode in an rf photoinjector. The charge yield verifies the generalized Fowler-Dubridge theory for multiphoton photoemission. The emission is verified to be prompt using a two pulse autocorrelation technique. The thermal emittance associated with the excess kinetic energy from the emission process is comparable with the one measured using frequency tripled uv laser pulses. In the high field of the rf gun, up to 50 pC of charge can be extracted from the cathode using a 80 fs long, 2 microJ, 800 nm pulse focused to a 140 mum rms spot size. Taking into account the efficiency of harmonic conversion, illuminating a cathode directly with ir laser pulses can be the most efficient way to employ the available laser power. PMID:20366937

  16. Post conductive keratoplasty visualization of rabbit cornea by multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Lo, Wen; Wang, Tsung-Jen; Hu, Fung-Rong; Dong, Chen-Yuan

    2007-07-01

    Conductive keratoplasty (CK) is a new refractive surgery for presbyopia and hyperopia patients. By applying radio frequency current at the peripheral regions of cornea, collagen, the most abundant composition of corneal stroma, shrinks due to the heat generated. The shrinkage at the periphery alters the corneal architecture and achieves clearer focus for near vision. In this work we use multiphoton microscopy to observe the post surgery structure variation at both submicron resolution and over a large region within the tissue. Since collagen can be induced to generate strong second harmonic generation (SHG) signal, multiphoton excitation provide direct visualization of collagen orientation within corneal stroma. In addition, since the SHG intensity of collagen tissue deteriorates with increasing thermal damage [1-3], our methodology can be used to characterize the extent of corneal stroma damage from the CK procedure. Finally, the influence of CK on the morphology and distribution of keratocytes can also be investigated by detecting multiphoton excited autofluorescence from the cells.

  17. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    PubMed Central

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  18. Evaluation of multiphoton effects in down-conversion

    SciTech Connect

    Yoshimi, Kazuyoshi; Koshino, Kazuki

    2010-04-15

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

  19. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    PubMed

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  20. High-intensity laser heating in liquids: Multiphoton absorption

    SciTech Connect

    Longtin, J.P.; Tien, C.L.

    1995-12-31

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in absorption and heating several orders of magnitude greater than classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for strong, controlled energy deposition in liquids without bulk plasma formation, shock waves, liquid ejection, etc., which is of interest for many laser-liquid applications, including laser desorption of liquid films, laser particle removal, and laser water removal from microdevices. This work develops a microscopically based model of the heating during multiphoton absorption in liquids. The dependence on pulse duration, intensity, wavelength, repetition rate, and liquid properties is discussed. Pure water exposed to 266 nm laser radiation is investigated, and a novel heating mechanism for water is proposed that uses multiple-wavelength laser pulses.

  1. Dissociation of H{sub 2}{sup +} and D{sub 2}{sup +} in an intense laser field

    SciTech Connect

    Ludwig, J.; Rottke, H.; Sandner, W.

    1997-09-01

    We report experimental investigations on dissociation of H{sub 2} and D{sub 2} in intense subpicosecond laser pulses at 1053 and 526.5 nm. Intensities in the range from {approx}5{times}10{sup 13} up to {approx}5{times}10{sup 14} W/cm{sup 2} were applied. The kinetic-energy distributions of the photoions H{sup +} and D{sup +}, which change dramatically with the light pulse peak intensity, give a detailed insight into the dissociation mechanisms. At 526.5 nm and low light intensity, ions from bond-softening dissociation and probably seven-photon resonant dissociative multiphoton ionization dominate the spectra. The resonant intermediate states are Rydberg states of the neutral molecules. At 1053 nm, above-threshold dissociation makes the main contribution to the spectra. Independent of the excitation wavelength, Coulomb explosion dissociation is found in the high-intensity limit. H{sub 2}{sup +} and D{sub 2}{sup +} photoionization, triggering this process, proceeds in the quasistatic limit by preferred tunnel or above-barrier ionization in a limited range of internuclear separations around 7.5 a.u. The ion kinetic-energy distributions seem to indicate that at 526.5 nm ionization starts from molecular ions light stabilized in a certain range of internuclear distances. In contrast, at 1053 nm, ionization seems to start from dissociating molecular ions. {copyright} {ital 1997} {ital The American Physical Society}

  2. Convergent perturbation analysis of intense coherent multiphoton interactions

    NASA Technical Reports Server (NTRS)

    Gower, M. C.; Yee, T. K.; Gustafson, T. K.; Fan, B.

    1979-01-01

    Use has been made of flow graphs to deduce Feenberg perturbation expansions for radiative interactions. It is demonstrated that these expansions can in certain cases be summed to provide closed form expressions for the molecular response. In particular, it is shown that the coherent state response can be obtained by the summation of a continued fraction perturbation expansion for the harmonic oscillator. Anharmonicity in the lower levels is treated and its shown to introduce Rabi flopping identifiable with multiphoton transitions among isolated tightly coupled subsystems of levels. Relevance to laser induced multiphoton excitation and energy level shift calculations in the presence of a strong field are also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    PubMed

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

    2014-12-15

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

  6. Fibre-coupled multiphoton microscope with adaptive motion compensation

    PubMed Central

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

    2015-01-01

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

  7. Photonic near-field imaging in multiphoton photoemission electron microscopy

    NASA Astrophysics Data System (ADS)

    Fitzgerald, J. P. S.; Word, R. C.; Saliba, S. D.; Könenkamp, R.

    2013-05-01

    We report the observation of optical near fields in a photonic waveguide of conductive indium tin oxide (ITO) using multiphoton photoemission electron microscopy (PEEM). Nonlinear two-photon photoelectron emission is enhanced at field maxima created by interference between incident 410-nm and coherently excited guided photonic waves, providing strong phase contrast. Guided modes are observed under both transverse magnetic field (TM) and transverse electric field (TE) polarized illuminations and are consistent with classical electromagnetic theory. Implications on the role of multiphoton PEEM in optical near-field imaging are discussed.

  8. Unambiguous atomic Bell measurement assisted by multiphoton states

    NASA Astrophysics Data System (ADS)

    Torres, Juan Mauricio; Bernád, József Zsolt; Alber, Gernot

    2016-05-01

    We propose and theoretically investigate an unambiguous Bell measurement of atomic qubits assisted by multiphoton states. The atoms interact resonantly with the electromagnetic field inside two spatially separated optical cavities in a Ramsey-type interaction sequence. The qubit states are postselected by measuring the photonic states inside the resonators. We show that if one is able to project the photonic field onto two coherent states on opposite sites of phase space, an unambiguous Bell measurement can be implemented. Thus, our proposal may provide a core element for future components of quantum information technology such as a quantum repeater based on coherent multiphoton states, atomic qubits and matter-field interaction.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  11. Multiphoton Coherent Manipulation in Large Spin Qubits

    NASA Astrophysics Data System (ADS)

    Chiorescu, Irinel

    2009-03-01

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

  12. Recurrent dissociative fugue.

    PubMed

    Mamarde, Abhishek; Navkhare, Praveen; Singam, Amrita; Kanoje, Akash

    2013-10-01

    Dissociative fugue is a rarely reported diagnostic entity. It is one of the least understood and yet clinically one of the most fascinating disorders in mental health. Here, we describe a case of fugue in a 32-year-old man who was brought to mental hospital with complete loss of memory for events pertaining to identity of self. This case illustrates the nature of presentation in hospital setting like mental hospital and effort taken to reintegrate his identity and reunite with his family. PMID:24379504

  13. THE DISSOCIATIVE TURN IN PSYCHOANALYSIS.

    PubMed

    Itzkowitz, Sheldon

    2015-06-01

    In his response to the Roundtable Discussions on what is effective in psychoanalytic psychotherapy, the author focuses on the renewed interest in the concept of dissociation that began to emerge toward the end of the 20th century. A contemporary psychoanalytic position informed by the impact of developmental trauma has led to an understanding of and interest in the dissociative mind. The actuality of trauma during infancy and early childhood is recognized as a key factor leading to the emergence of dissociative processes, the potential dissociative structuring of the mind, and mind being characterized by multiple, discontinuous, centers of consciousness. The therapeutic goal in the psychoanalytic work with fragmented patients is to establish communication and understanding between the dissociated self-states. The author offers two brief clinical examples of working with dissociated self-states. PMID:26177756

  14. Dissociative Electron Attachment

    NASA Astrophysics Data System (ADS)

    Arreola, Esmeralda; Esmeralda Arreola Collaboration; Leigh Hargreaves Collaboration

    Since the pioneering work of Boudiaffa et al., it has been understood that electrons, even with energies near or below the ionization threshold, are capable of initiating strand-breaks in human DNA. This discovery raised important questions for cancer treatments, since sub-ionizing electrons are known to be the most copiously produced secondary product of radiation therapy. But even to date these factors are largely excluded from dosimetry calculations. This lack of inclusion is, at least in part, certainly due to the dearth of fundamental data describing low-energy electron interactions with nucleotide molecules that form the basis of DNA. Understanding of how such slow electrons are able to damage DNA remains incomplete, but the strongly peaked nature of Boudiaffa et al.'s data gives strong hints at resonantly driven collision processes. DNA damage is therefore most likely driven by ``dissociative electron attachment'' (DEA). DEA is a rather complicated process to model due to the coupling of electronic and nuclear degrees of freedom in the molecule. At the California State University Fullerton, we are currently commissioning a new spectrometer to study dissociation channels, reaction rates and orientation effects in DEA collisions between slow electrons and nucleotide molecules. At the meeting we will present design parameters and commissioning data for this new apparatus.

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

    NASA Astrophysics Data System (ADS)

    Dahal, Sudhir

    During tumor removal surgery, due to the problems associated with obtaining high-resolution, real-time chemical images of where exactly the tumor ends and healthy tissue begins (tumor margining), it is often necessary to remove a much larger volume of tissue than the tumor itself. In the case of brain tumor surgery, however, it is extremely unsafe to remove excess tissue. Therefore, without an accurate image of the tumor margins, some of the tumor's finger-like projections are inevitably left behind in the surrounding parenchyma to grow again. For this reason, the development of techniques capable of providing high-resolution real-time images of tumor margins up to centimeters below the surface of a tissue is ideal for the diagnosis and treatment of tumors, as well as surgical guidance during brain tumor excision. A novel spectroscopic technique, non-resonant multiphoton photoacoustic spectroscopy (NMPPAS), is being developed with the capabilities of obtaining high-resolution subsurface chemical-based images of underlying tumors. This novel technique combines the strengths of multiphoton tissue spectroscopy and photoacoustic spectroscopy into a diagnostic methodology that will, ultimately, provide unparalleled chemical information and images to provide the state of sub-surface tissues. The NMPPAS technique employs near-infrared light (in the diagnostic window) to excite ultraviolet and/or visible light absorbing species deep below the tissue's surface. Once a multiphoton absorption event occurs, non-radiative relaxation processes generates a localized thermal expansion and subsequent acoustic wave that can be detected using a piezoelectric transducer. Since NMPPAS employs an acoustic detection modality, much deeper diagnoses can be performed than that is possible using current state of the art high-resolution chemical imaging techniques such as multiphoton fluorescence spectroscopy. NMPPAS was employed to differentiate between excised brain tumors (astrocytoma III

  16. Hyperglycemia associated dissociative fugue (organic dissociative disorder) in an elderly

    PubMed Central

    Ram, Dushad; Ashoka, H. G; Gowdappa, Basavnna

    2015-01-01

    Inadequate glycemic control in patients with diabetes is known to be associated with psychiatric disorders such as depression, anxiety disorder, and cognitive impairment. However, dissociative syndrome has not been reported so far. Here we are reporting a case of repeated dissociative fugue associated with hyperglycemia, in an elderly with type II diabetes. Possible neurobiological mechanism has been discussed. PMID:26286620

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

    PubMed

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

    2015-08-01

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

  18. Three-body dissociations: The photodissociation of dimethyl sulfoxide at 193 nm

    SciTech Connect

    Blank, D.A.; North, S.W.; Stranges, D.

    1997-04-01

    When a molecule with two equivalent chemical bonds is excited above the threshold for dissociation of both bonds, how the rupture of the two bonds is temporally coupled becomes a salient question. Following absorption at 193 nm dimethyl sulfoxide (CH{sub 3}SOCH{sub 3}) contains enough energy to rupture both C-S bonds. This can happen in a stepwise (reaction 1) or concerted (reaction 2) fashion where the authors use rotation of the SOCH{sub 3} intermediate prior to dissociation to define a stepwise dissociation: (1) CH{sub 3}SOCH{sub 3} {r_arrow} 2CH{sub 3} + SO; (2a) CH{sub 3}SOCH{sub 3} {r_arrow} CH{sub 3} + SOCH{sub 3}; and (2b) SOCH{sub 3} {r_arrow} SO + CH{sub 3}. Recently, the dissociation of dimethyl sulfoxide following absorption at 193 nm was suggested to involve simultaneous cleavage of both C-S bonds on an excited electronic surface. This conclusion was inferred from laser induced fluorescence (LIF) and resonant multiphoton ionization (2+1 REMPI) measurements of the internal energy content in the CH{sub 3} and SO photoproducts and a near unity quantum yield measured for SO. Since this type of concerted three body dissociation is very interesting and a rather rare event in photodissociation dynamics, the authors chose to investigate this system using the technique of photofragment translational spectroscopy at beamline 9.0.2.1. The soft photoionization provided by the VUV undulator radiation allowed the authors to probe the SOCH{sub 3} intermediate which had not been previously observed and provided good evidence that the dissociation of dimethyl sulfoxide primarily proceeds via a two step dissociation, reaction 2.

  19. Dissociative States and Neural Complexity

    ERIC Educational Resources Information Center

    Bob, Petr; Svetlak, Miroslav

    2011-01-01

    Recent findings indicate that neural mechanisms of consciousness are related to integration of distributed neural assemblies. This neural integration is particularly vulnerable to past stressful experiences that can lead to disintegration and dissociation of consciousness. These findings suggest that dissociation could be described as a level of…

  20. Multiphoton imaging of excised normal skin and keloid scar: preliminary investigations

    NASA Astrophysics Data System (ADS)

    Brewer, Michael B.; Yeh, Alvin T.; Torkian, Behrooz; Sun, Chung-Ho; Tromberg, Bruce J.; Wong, Brian J.

    2004-07-01

    Wound healing is a physiologic process that acts to repair disruptions in the continuity of tissue caused by injury or surgical incision. Keloids and hypertrophic scars are forms of aberrant wound healing, which are characterized by the overproduction of collagen, resulting in an excessive amount of scar tissue. Keloid tumors, by definition, grow outside the boundary of the original tissue damage. Multiphoton microscopy (MPM) is an imaging technique which allows imaging of living specimens, without the use of fixation or stains. Images of collagen fibers are produced by the second harmonic signal intensity generated by endogenous fluorescence through excitation by infrared laser light. A postauricular keloid tumor was excised from a patient. The tissue was dissected, and a portion was imaged using MPM. Normal skin tissue was isolated from a patient undergoing a facelift. A portion of this tissue was also dissected and imaged using MPM. MPM images were taken using a 63X water immersion objective lens on a two-photon microscope and a titanium-sapphire laser. Images were taken beginning at the surface of the tissue and moving in at intervals of 200 nm to a final depth of 30 μm. The two-photon images were used to reconstruct three-dimensional representations of the collagen matrix within the tissues, which are readily contrasted. Density of the collagen within each tissue was also ascertained using depth dependant decay of the image intensity. Multiphoton imaging was successfully used to image the collagen matrix of normal skin and a keloid scar, demonstrating differences in their microstructures.

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

    PubMed

    Huang, Chih-Chia; Liu, Tzu-Ming

    2015-11-18

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

  2. Multiphoton dynamics of qutrits in the ultrastrong coupling regime with a quantized photonic field

    NASA Astrophysics Data System (ADS)

    Avetissian, H. K.; Avetissian, A. K.; Mkrtchian, G. F.; Kibis, O. V.

    2015-12-01

    Multiphoton resonant excitation of a three-state quantum system (a qutrit) with a single-mode photonic field is considered in the ultrastrong coupling regime, when the qutrit-photonic field coupling rate is comparable to appreciable fractions of the photon frequency. For ultrastrong couplings, the obtained solutions of the Schrödinger equation that reveal multiphoton Rabi oscillations in qutrits with the interference effects leading to the collapse and revival of atomic excitation probabilities at the direct multiphoton resonant transitions.

  3. Multiphoton nanosurgery in cells and tissues

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Stracke, Frank; Sauer, Daniel; Martin, Sven; König, Karsten

    2006-02-01

    Near infrared (NIR) femtosecond laser microscopes enable the user to perform highly precise nanosurgery. Tissue components, cells and single organelles of cells inside tumor-sphaeroids and tissues can be precisely manipulated and optically knocked out without collateral damage. In addition, the monitoring effects of nanosurgery in situ using two photon excitation of auto fluorescence of endogenous fluorophores can be performed quite easily with a sub-cellular resolution. This method may become a useful instrument for nano manipulation and nano-surgery in several fields of life sciences.

  4. Dissociative absorption: An empirically unique, clinically relevant, dissociative factor.

    PubMed

    Soffer-Dudek, Nirit; Lassri, Dana; Soffer-Dudek, Nir; Shahar, Golan

    2015-11-01

    Research of dissociative absorption has raised two questions: (a) Is absorption a unique dissociative factor within a three-factor structure, or a part of one general dissociative factor? Even when three factors are found, the specificity of the absorption factor is questionable. (b) Is absorption implicated in psychopathology? Although commonly viewed as "non-clinical" dissociation, absorption was recently hypothesized to be specifically associated with obsessive-compulsive symptoms. To address these questions, we conducted exploratory and confirmatory factor analyses on 679 undergraduates. Analyses supported the three-factor model, and a "purified" absorption scale was extracted from the original inclusive absorption factor. The purified scale predicted several psychopathology scales. As hypothesized, absorption was a stronger predictor of obsessive-compulsive symptoms than of general psychopathology. In addition, absorption was the only dissociative scale that longitudinally predicted obsessive-compulsive symptoms. We conclude that absorption is a unique and clinically relevant dissociative tendency that is particularly meaningful to obsessive-compulsive symptoms. PMID:26241024

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

    SciTech Connect

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

    1990-10-01

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

  6. Moxifloxacin: Clinically compatible contrast agent for multiphoton imaging

    PubMed Central

    Wang, Taejun; Jang, Won Hyuk; Lee, Seunghun; Yoon, Calvin J.; Lee, Jun Ho; Kim, Bumju; Hwang, Sekyu; Hong, Chun-Pyo; Yoon, Yeoreum; Lee, Gilgu; Le, Viet-Hoan; Bok, Seoyeon; Ahn, G-One; Lee, Jaewook; Gho, Yong Song; Chung, Euiheon; Kim, Sungjee; Jang, Myoung Ho; Myung, Seung-Jae; Kim, Myoung Joon; So, Peter T. C.; Kim, Ki Hean

    2016-01-01

    Multiphoton microscopy (MPM) is a nonlinear fluorescence microscopic technique widely used for cellular imaging of thick tissues and live animals in biological studies. However, MPM application to human tissues is limited by weak endogenous fluorescence in tissue and cytotoxicity of exogenous probes. Herein, we describe the applications of moxifloxacin, an FDA-approved antibiotic, as a cell-labeling agent for MPM. Moxifloxacin has bright intrinsic multiphoton fluorescence, good tissue penetration and high intracellular concentration. MPM with moxifloxacin was demonstrated in various cell lines, and animal tissues of cornea, skin, small intestine and bladder. Clinical application is promising since imaging based on moxifloxacin labeling could be 10 times faster than imaging based on endogenous fluorescence. PMID:27283889

  7. Nanoparticle metrology in sol-gels using multiphoton excited fluorescence

    NASA Astrophysics Data System (ADS)

    Karolin, J.; Geddes, C. D.; Wynne, K.; Birch, D. J. S.

    2002-01-01

    We have developed a method of measuring the growth of nanoparticles during sol-gel glass formation based on labelling the particle with a fluorescent dye and determining the multiphoton excited decay of fluorescence anisotropy due to Brownian rotation. Multiphoton excitation is shown to give a higher dynamic range of measurement than one-photon excitation. We illustrate the sub-nanometre resolution and stability of our approach by detecting a 0.8-1.1 nm silica particle hydrodynamic mean radius increase in a tetramethylorthosilicate sol at pH 2.3 labelled with rhodamine 6G and observed over ≈4 weeks and also with a stable silica colloid of radius 6 nm, pH 8.9, labelled with a 6-methoxyquinoline-type dye.

  8. Multiphoton Imaging of Ultrasound Bioeffects in the Murine Brain

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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.

  9. Moxifloxacin: Clinically compatible contrast agent for multiphoton imaging.

    PubMed

    Wang, Taejun; Jang, Won Hyuk; Lee, Seunghun; Yoon, Calvin J; Lee, Jun Ho; Kim, Bumju; Hwang, Sekyu; Hong, Chun-Pyo; Yoon, Yeoreum; Lee, Gilgu; Le, Viet-Hoan; Bok, Seoyeon; Ahn, G-One; Lee, Jaewook; Gho, Yong Song; Chung, Euiheon; Kim, Sungjee; Jang, Myoung Ho; Myung, Seung-Jae; Kim, Myoung Joon; So, Peter T C; Kim, Ki Hean

    2016-01-01

    Multiphoton microscopy (MPM) is a nonlinear fluorescence microscopic technique widely used for cellular imaging of thick tissues and live animals in biological studies. However, MPM application to human tissues is limited by weak endogenous fluorescence in tissue and cytotoxicity of exogenous probes. Herein, we describe the applications of moxifloxacin, an FDA-approved antibiotic, as a cell-labeling agent for MPM. Moxifloxacin has bright intrinsic multiphoton fluorescence, good tissue penetration and high intracellular concentration. MPM with moxifloxacin was demonstrated in various cell lines, and animal tissues of cornea, skin, small intestine and bladder. Clinical application is promising since imaging based on moxifloxacin labeling could be 10 times faster than imaging based on endogenous fluorescence. PMID:27283889

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  11. Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  12. Moxifloxacin: Clinically compatible contrast agent for multiphoton imaging

    NASA Astrophysics Data System (ADS)

    Wang, Taejun; Jang, Won Hyuk; Lee, Seunghun; Yoon, Calvin J.; Lee, Jun Ho; Kim, Bumju; Hwang, Sekyu; Hong, Chun-Pyo; Yoon, Yeoreum; Lee, Gilgu; Le, Viet-Hoan; Bok, Seoyeon; Ahn, G.-One; Lee, Jaewook; Gho, Yong Song; Chung, Euiheon; Kim, Sungjee; Jang, Myoung Ho; Myung, Seung-Jae; Kim, Myoung Joon; So, Peter T. C.; Kim, Ki Hean

    2016-06-01

    Multiphoton microscopy (MPM) is a nonlinear fluorescence microscopic technique widely used for cellular imaging of thick tissues and live animals in biological studies. However, MPM application to human tissues is limited by weak endogenous fluorescence in tissue and cytotoxicity of exogenous probes. Herein, we describe the applications of moxifloxacin, an FDA-approved antibiotic, as a cell-labeling agent for MPM. Moxifloxacin has bright intrinsic multiphoton fluorescence, good tissue penetration and high intracellular concentration. MPM with moxifloxacin was demonstrated in various cell lines, and animal tissues of cornea, skin, small intestine and bladder. Clinical application is promising since imaging based on moxifloxacin labeling could be 10 times faster than imaging based on endogenous fluorescence.

  13. Waveguide characterization with multi-photon photoemission electron microscopy

    NASA Astrophysics Data System (ADS)

    Fitzgerald, J. P. S.; Word, Robert C.; Saliba, Sebastian; Koenenkamp, Rolf

    2012-10-01

    Multi-photon photoemission electron microscopy (PEEM) images surface interactions of visible light with matter, showing electromagnetic (EM) waves that propagate at or near the surface. Images are interferometric, showing where incident and surface waves are in-phase (bright) and out-of-phase (dark), with strong contrast between regions of high and low rates of photoelectron emission. Interferogram analysis can determine the amplitude, wavelength, phase evolution, and propagation decay length of the surface waves. Most multi-photon PEEM studies focus on surface plasmon polaritons. We show that this technique can also be applied to conducting thin-film waveguides, measuring the properties of confined EM waves in a two-mode slab waveguide made of indium tin oxide on glass, which are consistent with waveguide theory. This research was funded by the US Department of Energy Basic Science Office under contract DE-FG02-10ER46406.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  15. Recurrent Episodes of Dissociative Fugue

    PubMed Central

    Angothu, Hareesh; Pabbathi, Lokeswar Reddy

    2016-01-01

    Dissociative fugue is rare entity to encounter with possible differentials of epilepsy and malingering. It is one of the dissociative disorders rarely seen in clinical practice more often because of the short lasting nature of this condition. This might also be because of organized travel of the individuals during the episodes and return to their families after the recovery from episodes. This is a case description of a patient who has experienced total three episodes of dissociative fugue. The patient has presented during the third episode and two prior episodes were diagnosed as fugue episodes retrospectively based on the history. Planned travel in this case by the patient to a distant location was prevented because of early diagnosis and constant vigilance till the recovery. As in this case, it may be more likely that persons with Dissociative fugue may develop similar episodes if they encounter exceptional perceived stress. However, such conclusions may require follow-up studies. PMID:27114633

  16. Influence of Vacuum Cooling on Escherichia coli O157:H7 Infiltration in Fresh Leafy Greens via a Multiphoton-Imaging Approach

    PubMed Central

    Vonasek, Erica

    2015-01-01

    Microbial pathogen infiltration in fresh leafy greens is a significant food safety risk factor. In various postharvest operations, vacuum cooling is a critical process for maintaining the quality of fresh produce. The overall goal of this study was to evaluate the risk of vacuum cooling-induced infiltration of Escherichia coli O157:H7 into lettuce using multiphoton microscopy. Multiphoton imaging was chosen as the method to locate E. coli O157:H7 within an intact lettuce leaf due to its high spatial resolution, low background fluorescence, and near-infrared (NIR) excitation source compared to those of conventional confocal microscopy. The variables vacuum cooling, surface moisture, and leaf side were evaluated in a three-way factorial study with E. coli O157:H7 on lettuce. A total of 188 image stacks were collected. The images were analyzed for E. coli O157:H7 association with stomata and E. coli O157:H7 infiltration. The quantitative imaging data were statistically analyzed using analysis of variance (ANOVA). The results indicate that the low-moisture condition led to an increased risk of microbial association with stomata (P < 0.05). Additionally, the interaction between vacuum cooling levels and moisture levels led to an increased risk of infiltration (P < 0.05). This study also demonstrates the potential of multiphoton imaging for improving sensitivity and resolution of imaging-based measurements of microbial interactions with intact leaf structures, including infiltration. PMID:26475109

  17. Relaxation channels of multi-photon excited xenon clusters

    SciTech Connect

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

    2015-09-21

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

  18. Relaxation channels of multi-photon excited xenon clusters

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  19. Femtosecond Light Source for Phase-Controlled Multiphoton Ionization

    SciTech Connect

    Sokolov, A. V.; Walker, D. R.; Yavuz, D. D.; Yin, G. Y.; Harris, S. E.

    2001-07-16

    We describe a femtosecond Raman light source with more than an octave of optical bandwidth. We use this source to demonstrate phase control of multiphoton ionization under conditions where ionization requires eleven photons of the lowest frequency of the spectrum or five photons of the highest frequency. The nonlinearity of the photoionization process allows us to characterize the light source. Experiment-to-theory comparison implies generation of a near single-cycle waveform.

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

    SciTech Connect

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

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

    PubMed

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

    2015-08-01

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

  3. Multicolor multiphoton microscopy based on a nanosecond supercontinuum laser source.

    PubMed

    Lefort, Claire; O'Connor, Rodney P; Blanquet, Véronique; Magnol, Laetitia; Kano, Hideaki; Tombelaine, Vincent; Lévêque, Philippe; Couderc, Vincent; Leproux, Philippe

    2016-07-01

    Multicolor multiphoton microscopy is experimentally demonstrated for the first time on a spectral bandwidth of excitation of 300 nm (full width half maximum) thanks to the implementation a nanosecond supercontinuum (SC) source compact and simple with a low repetition rate. The interest of such a wide spectral bandwidth, never demonstrated until now, is highlighted in vivo: images of glioma tumor cells stably expressing eGFP grafted on the brain of a mouse and its blood vessels network labelled with Texas Red(®) are obtained. These two fluorophores have a spectral bandwidth covering the whole 300 nm available. In parallel, a similar image quality is obtained on a sample of mouse muscle in vitro when excited with this nanosecond SC source or with a classical high rate, femtosecond and quasi monochromatic laser. This opens the way for (i) a simple and very complete biological characterization never performed to date with multiphoton processes, (ii) multiple means of contrast in nonlinear imaging allowed by the use of numerous fluorophores and (iii) other multiphoton processes like three-photon ones. PMID:26872004

  4. Dissociative disorders in DSM-5.

    PubMed

    Spiegel, David; Lewis-Fernández, Roberto; Lanius, Ruth; Vermetten, Eric; Simeon, Daphne; Friedman, Matthew

    2013-01-01

    The rationale, research literature, and proposed changes to the dissociative disorders and conversion disorder in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) are presented. Dissociative identity disorder will include reference to possession as well as identity fragmentation, to make the disorder more applicable to culturally diverse situations. Dissociative amnesia will include dissociative fugue as a subtype, since fugue is a rare disorder that always involves amnesia but does not always include confused wandering or loss of personality identity. Depersonalization disorder will include derealization as well, since the two often co-occur. A dissociative subtype of posttraumatic stress disorder (PTSD), defined by the presence of depersonalization or derealization in addition to other PTSD symptoms, is being recommended, based upon new epidemiological and neuroimaging evidence linking it to an early life history of adversity and a combination of frontal activation and limbic inhibition. Conversion disorder (functional neurological symptom disorder) will likely remain with the somatic symptom disorders, despite considerable dissociative comorbidity. PMID:23394228

  5. Global functioning and disability in dissociative disorders.

    PubMed

    Mueller-Pfeiffer, Christoph; Rufibach, Kaspar; Perron, Noelle; Wyss, Daniela; Kuenzler, Cornelia; Prezewowsky, Cornelia; Pitman, Roger K; Rufer, Michael

    2012-12-30

    Dissociative disorders are frequent comorbid conditions of other mental disorders. Yet, there is controversy about their clinical relevance, and little systematic research has been done on how they influence global functioning. Outpatients and day care patients (N=160) of several psychiatric units in Switzerland were assessed with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV Axis I Disorders, Structured Clinical Interview for DSM-IV Dissociative Disorders, Global Assessment of Functioning Scale, and World Health Organization Disability Assessment Schedule-II. The association between subjects with a dissociative disorder (N=30) and functional impairment after accounting for non-dissociative axis I disorders was evaluated by linear regression models. We found a proportion of 18.8% dissociative disorders (dissociative amnesia=0%, dissociative fugue=0.6%, depersonalization disorder=4.4%, dissociative identity disorder=7.5%, dissociative disorder-not-otherwise-specified=6.3%) across treatment settings. Adjusted for other axis I disorders, subjects with a comorbid dissociative identity disorder or dissociative disorder-not-otherwise-specified had a median global assessment of functioning score that was 0.86 and 0.88 times, respectively, the score of subjects without a comorbid dissociative disorder. These findings support the hypothesis that complex dissociative disorders, i.e., dissociative identity disorder and dissociative disorder-not-otherwise-specified, contribute to functional impairment above and beyond the impact of co-existing non-dissociative axis I disorders, and that they qualify as "serious mental illness". PMID:22578820

  6. Deuterium enrichment by selective photoinduced dissociation of a multihalogenated organic compound

    DOEpatents

    Marling, John B.; Herman, Irving P.

    1981-01-01

    A method for deuterium enrichment by photoinduced dissociation which uses as the deuterium source a multihalogenated organic compound selected from the group consisting of a dihalomethane, a trihalomethane, a 1,2-dihaloethene, a trihaloethene, a tetrahaloethane and a pentahaloethane. The multihalogenated organic compound is subjected to intense infrared radiation at a preselected wavelength to selectively excite and thereby induce dissociation of substantially only those molecules containing deuterium to provide a deuterium enriched dissociation product. The deuterium enriched product may be combusted with oxygen to provide deuterium enriched water. The deuterium depleted undissociated molecules may be redeuterated by treatment with a deuterium source such as water.

  7. Deuterium enrichment by selective photo-induced dissociation of an organic carbonyl compound

    DOEpatents

    Marling, John B.

    1981-01-01

    A method for producing a deuterium enriched material by photoinduced dissociation which uses as the working material a gas phase photolytically dissociable organic carbonyl compound containing at least one hydrogen atom bonded to an atom which is adjacent to a carbonyl group and consisting of molecules wherein said hydrogen atom is present as deuterium and molecules wherein said hydrogen atom is present as another isotope of hydrogen. The organic carbonyl compound is subjected to intense infrared radiation at a preselected wavelength to selectively excite and thereby induce dissociation of the deuterium containing species to yield a deuterium enriched stable molecular product. Undissociated carbonyl compound, depleted in deuterium, is preferably redeuterated for reuse.

  8. Dissociative experiences and dissociative minds: Exploring a nomological network of dissociative functioning.

    PubMed

    Schimmenti, Adriano

    2016-01-01

    In this study, the psychometric properties of the Dissociative Experiences Scale-II (DES-II) were tested in a sample of Italian adults, and a nomological network of dissociative functioning based on current psychodynamic research was examined. A total of 794 participants (55% females) ranging in age from 18 to 64 completed the DES-II and other measures of theory of mind, alexithymia, attachment style, and empathy. The Italian translation of the DES-II showed high internal consistency, adequate item-to-scale homogeneity, and good split-half reliability. A single-factor solution including the 8 items of pathological dissociation (DES-T) adequately fit the data. Participants who reported higher levels of dissociative experiences showed significantly lower scores on theory of mind and empathy than other participants. They also showed significantly higher scores on alexithymia, preoccupied attachment, and fearful attachment. Results of the study support the view that people who suffer from severe dissociative experiences may also have difficulties mentalizing and regulating affects and that they may feel uncomfortable in close relationships because they have a negative view of the self. This can inform clinical work with dissociative individuals, who could benefit from therapies that consider their potential problems with mentalization, empathy, affect regulation, and attachment. PMID:26507547

  9. Dissociative symptomatology in cancer patients

    PubMed Central

    Civilotti, Cristina; Castelli, Lorys; Binaschi, Luca; Cussino, Martina; Tesio, Valentina; Di Fini, Giulia; Veglia, Fabio; Torta, Riccardo

    2015-01-01

    Introduction: The utilization of the post-traumatic stress disorder (PTSD) diagnostic spectrum is currently being debated to categorize psychological adjustment in cancer patients. The aims of this study were to: (1) evaluate the presence of cancer-related traumatic dissociative symptomatology in a sample of cancer patients; (2) examine the correlation of cancer-related dissociation and sociodemographic and medical variables, anxiety, depression, and post-traumatic stress symptomatology; (3) investigate the predictors of cancer-related dissociation. Methods: Ninety-two mixed cancer patients (mean age: 58.94, ds = 10.13) recruited from two hospitals in northern Italy were administered a questionnaire on sociodemographic and medical characteristics, the Karnofsky Scale to measure the level of patient activity and medical care requirements, the Hospital Anxiety and Depression Scale (HADS) to evaluate the presence of anxiety and depression, the Impact of Event Scale Revised (IES-R) to assess the severity of intrusion, avoidance, and hypervigilance, and the Peritraumatic Dissociative Experiences Questionnaire (PDEQ) to quantify the traumatic dissociative symptomatology. Results: 31.5% of participants report a PDEQ score above the cutoff. The results indicated that dissociative symptomatology was positively correlated with HADS scores (HADS-Anxiety: r = 0.476, p < 0.001; HADS-Depression: r = 0.364, p < 0.001) and with IES-R scores (IES-R-Intrusion: r = 0.698, p < 0.001; IES-R-Avoidance: r = 0.619, p < 0.001; IES-R- Hypervigilance: r = 0.681, p < 0.001). A stepwise regression analysis was performed in order to find the predictors of cancer-related traumatic dissociative symptomatology. The results converged on a three predictor model revealing that IES-R-Intrusion, IES-R-Avoidance, and IES-R-Hyperarousal accounted for 53.9% of the explained variance. Conclusion: These findings allow us to hypothesize a specific psychological reaction which may be ascribed to the traumatic

  10. In vivo multiphoton tomography and fluorescence lifetime imaging of human brain tumor tissue.

    PubMed

    Kantelhardt, Sven R; Kalasauskas, Darius; König, Karsten; Kim, Ella; Weinigel, Martin; Uchugonova, Aisada; Giese, Alf

    2016-05-01

    High resolution multiphoton tomography and fluorescence lifetime imaging differentiates glioma from adjacent brain in native tissue samples ex vivo. Presently, multiphoton tomography is applied in clinical dermatology and experimentally. We here present the first application of multiphoton and fluorescence lifetime imaging for in vivo imaging on humans during a neurosurgical procedure. We used a MPTflex™ Multiphoton Laser Tomograph (JenLab, Germany). We examined cultured glioma cells in an orthotopic mouse tumor model and native human tissue samples. Finally the multiphoton tomograph was applied to provide optical biopsies during resection of a clinical case of glioblastoma. All tissues imaged by multiphoton tomography were sampled and processed for conventional histopathology. The multiphoton tomograph allowed fluorescence intensity- and fluorescence lifetime imaging with submicron spatial resolution and 200 picosecond temporal resolution. Morphological fluorescence intensity imaging and fluorescence lifetime imaging of tumor-bearing mouse brains and native human tissue samples clearly differentiated tumor and adjacent brain tissue. Intraoperative imaging was found to be technically feasible. Intraoperative image quality was comparable to ex vivo examinations. To our knowledge we here present the first intraoperative application of high resolution multiphoton tomography and fluorescence lifetime imaging of human brain tumors in situ. It allowed in vivo identification and determination of cell density of tumor tissue on a cellular and subcellular level within seconds. The technology shows the potential of rapid intraoperative identification of native glioma tissue without need for tissue processing or staining. PMID:26830089

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  12. Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets.

    PubMed

    Kautsch, Andreas; Koch, Markus; Ernst, Wolfgang E

    2015-05-14

    We have investigated photoinduced chemical reaction dynamics of cold, isolated Cr2 molecules in helium nanodroplets (HeN), exploiting the quantum state specific spatial separation of solvated and surface locations on the droplet. The molecules are excited to achieve dissociation to a ground state (a(7)S3) and a metastable state (a(5)S2) atom. State specific spatial separation, in combination with efficient translational cooling to avoid ejection, causes the ground state atom to be solvated inside the droplet while the metastable atom migrates to the surface. A barrier between the two reactants formed by the HeN prevents recombination. We apply a resonance-enhanced multiphoton ionization scheme including the y(5)P°(1,2,3) <-- a(5)S(2) transition of the surface atom as well as a two-laser scheme including the y(7)P°(2,3,4) <-- a(7)S(3) transition of the solvated atom in order to verify the locations and separation of the dissociation products. Furthermore, ionization of the a(5)S2 surface atom triggers solvation followed by geminate recombination with the a(7)S3 atom, which is verified by the detection of Cr2(+) molecular ions. For small Cr clusters, our results indicate that they may be composed of chromium dimers that exhibit the same dissociation behavior. PMID:25894482

  13. Diffraction dissociation at the LHC

    NASA Astrophysics Data System (ADS)

    Jenkovszky, László; Orava, Risto; Salii, Andrii

    2013-04-01

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  14. Diffraction dissociation at the LHC

    SciTech Connect

    Jenkovszky, Laszlo; Orava, Risto; Salii, Andrii

    2013-04-15

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  15. Dissociation of pleasure in psychopathology.

    PubMed

    Brown, S L

    1981-01-01

    This paper analyzes the development of the concept of dissociation from 19th century psychological theory through 20th century neurophysiological thought. Recent research is discussed, indicating that normal individuals show an "association" between emitted pleasurable behavior and self-perception of pleasurable activity, whereas depressives and schizophrenics show a lack of association, or "dissociation," between these measures. concomitantly, depressives show an abnormal degree of association between the experience and expression of negative affect. Such a discrepancy in systems of affect is considered as both an important pathological element in mental disorder and also as a valuable new research tool for studying etiology, differential diagnosis, and therapeutic efficacy in psychobiological illness. PMID:7005394

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

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Fischer, Peter; Koenig, Karsten

    2004-09-01

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

  17. High-resolution multiphoton tomography of human skin in vivo and in vitro

    NASA Astrophysics Data System (ADS)

    Riemann, Iris; Dimitrov, Enrico; Fischer, Peter; Reif, Annette; Kaatz, Martin; Elsner, Peter; Konig, Karsten

    2004-09-01

    The novel compact femtosecond NIR (near infrared) laser imaging system DermaInspect was used to perform for the first time in vivo high resolution non-invasive 4D tomography of human skin based on multiphoton autofluorescence imaging and second harmonic generation (SHG). Using fast galvoscan mirrors, a time correlated single photon counting (TCSPC) module and femtosecond 80 MHz laser pulses in the spectral range of 750 nm-850 nm human skin was analyzed with subcellular spatial resolution (3D) and 250 ps temporal resolution (4D). The non-linear induced autofluorescence originates from naturally endogenous fluorophores and protein structures like NAD(P)H, flavins, phorphyrins, melanin, elastin and collagen. Collagenous structures were detected using SHG. Tissues of patients with dermatological disorders like nevi and melanoma have been investigated with a clear visualization of cells and intratissue structures. Further characterization of those components was performed by the fluorescence lifetime imaging (FLIM) and the determination of two photon excitation spectra. This method of non invasive high resolution optical biopsy provides a painless diagnostic tool for dermatological applications.

  18. Signal enhancement in multiphoton imaging by the use of coated glass substrates

    PubMed Central

    Lee, Sheng-Lin; Guo, Han-Wen; Chen, Yang-Fan; Dong, Chen-Yuan

    2015-01-01

    In nonlinear optical imaging of biological specimens, more than half of the generated luminescence signal is lost, when signal collection is performed in the epi-illuminated geometry. In this study, we enhanced the collected luminescence signal by the use of alternating multiply-coated layers of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) on standard microscope cover glasses that has high transmission in the near-infrared wavelength region and high reflection of the visible, luminescence signal. Our coating is biocompatible, allows visual examination of the specimens and optimize collection of the luminescence signal. We demonstrated this approach on a number of specimens including sulforhodamine solution, fluorescence microspheres, and labeled 3T3 cells. In all cases, the use of coated cover glass enhanced signal, optimally by a factor of about 2. Image analysis of labeled 3T3 cells also shows signal enhancement did not contribute to additional photobleaching. Our results show that properly designed coated cover glass can enhance detected signal in multiphoton microscopy and result in improved image quality. PMID:26417521

  19. Signal enhancement in multiphoton imaging by the use of coated glass substrates.

    PubMed

    Lee, Sheng-Lin; Guo, Han-Wen; Chen, Yang-Fan; Dong, Chen-Yuan

    2015-09-01

    In nonlinear optical imaging of biological specimens, more than half of the generated luminescence signal is lost, when signal collection is performed in the epi-illuminated geometry. In this study, we enhanced the collected luminescence signal by the use of alternating multiply-coated layers of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) on standard microscope cover glasses that has high transmission in the near-infrared wavelength region and high reflection of the visible, luminescence signal. Our coating is biocompatible, allows visual examination of the specimens and optimize collection of the luminescence signal. We demonstrated this approach on a number of specimens including sulforhodamine solution, fluorescence microspheres, and labeled 3T3 cells. In all cases, the use of coated cover glass enhanced signal, optimally by a factor of about 2. Image analysis of labeled 3T3 cells also shows signal enhancement did not contribute to additional photobleaching. Our results show that properly designed coated cover glass can enhance detected signal in multiphoton microscopy and result in improved image quality. PMID:26417521

  20. Dynamic Multiphoton Microscopy: Focusing Light on Acute Kidney Injury

    PubMed Central

    Molitoris, Bruce A.

    2014-01-01

    Acute kidney injury (AKI) is a major global health problem; much research has been conducted on AKI, and numerous agents have shown benefit in animal studies, but none have translated into treatments. There is, therefore, a pressing unmet need to increase knowledge of the pathophysiology of AKI. Multiphoton microscopy (MPM) provides a tool to non-invasively visualize dynamic events in real time and at high resolution in rodent kidneys, and in this article we review its application to study novel mechanisms and treatments in different forms of AKI. PMID:25180263

  1. The nature of multiphoton fluorescence from red blood cells

    NASA Astrophysics Data System (ADS)

    Saytashev, Ilyas; Murphy, Michael; Osseiran, Sam; Spence, Dana M.; Evans, Conor L.; Dantus, Marcos

    2016-03-01

    We report on the nature of multiphoton excited fluorescence observed from human erythrocytes (red blood cells RBC's) and their "ghosts" following 800nm sub-15 fs excitation. The detected optical signal is assigned as two-photon excited fluorescence from hemoglobin. Our findings are supported by wavelength-resolved fluorescence lifetime decay measurements using time-correlated single photon counting system from RBC's, their ghosts as well as in vitro samples of various fluorophores including riboflavin, NADH, NAD(P)H, hemoglobin. We find that low-energy and short-duration pulses allow two-photon imaging of RBC's, but longer more intense pulses lead to their destruction.

  2. Multiphoton excitation of organic chromophores in microbubble resonators

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory A.; Kieu, Khanh; Norwood, Robert A.

    2014-03-01

    We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW.

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

    SciTech Connect

    Wessel, J.

    1995-12-28

    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.

  4. Integrated spectrometer design with application to multiphoton microscopy.

    PubMed

    Chandler, Eric V; Durfee, Charles G; Squier, Jeffrey A

    2011-01-01

    We present a prism-based spectrometer integrated into a multifocal, multiphoton microscope. The multifocal configuration facilitates interrogation of samples under different excitation conditions. Notably, the image plane of the microscope and the image plane of the spectrometer are coincident eliminating the need for an intermediate image plane containing an entrance slit. An EM-CCD detector provides sufficient gain for spectral interrogation of single-emitters. We employ this spectrometer to observe spectral shifts in the two-photon excitation fluorescence emission of single CdSe nanodots as a function of excitation polarization. PMID:21263548

  5. Multi-photon microscope driven by novel green laser pump

    NASA Astrophysics Data System (ADS)

    Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin; Andersen, Peter E.

    2016-03-01

    Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal system. However, translation is hindered due to the high cost, high training demand and large footprint of a standard setup. We show in this article that minification of the setup, while also reducing cost and complexity, is indeed possible without compromising on image quality, by using a novel diode laser replacing the commonly used conventional solid state laser as the pump for the femtosecond system driving the imaging.

  6. Multifocal multiphoton microscopy based on a spatial light modulator

    PubMed Central

    Shao, Y.; Qin, W.; Liu, H.; Peng, X.; Niu, H.

    2013-01-01

    We present a new multifocal multiphoton microscope that employs a programmable spatial light modulator to generate dynamic multifocus arrays which can be rapidly scanned by changing the incident angle of the laser beam using a pair of galvo scanners. Using this microscope, we can rapidly select the number and the spatial density of focal points in a multifocus array, as well as the locations and shapes of arrays according to the features of the areas of interest in the field of view without any change to the hardware. PMID:23894222

  7. Multiphoton ionization of ions, neutrals, and clusters. Progress report

    SciTech Connect

    Wessel, J.

    1991-06-28

    Scientific results are summarized from a three year research program on multiphoton ionization in aromatic molecules, clusters, and their ions. As originally proposed, the studies elucidated a new cluster ionization mechanism, characterized properties of long range intermolecular interactions, and investigated electronic transitions of aromatic cations cooled in a supersonic beam. The studies indicate that the new cluster ionization mechanism is highly efficient and dominates conventional 1 + 1 resonant ionization. In the case of the dimer of the large aromatic molecule fluorene, the results suggest that excimer formation competes with a direct ionization process. Highly selective excitonic spectra have been identified for several cluster species.

  8. Exploration of multiphoton entangled states by using weak nonlinearities

    NASA Astrophysics Data System (ADS)

    He, Ying-Qiu; Ding, Dong; Yan, Feng-Li; Gao, Ting

    2016-01-01

    We propose a fruitful scheme for exploring multiphoton entangled states based on linear optics and weak nonlinearities. Compared with the previous schemes the present method is more feasible because there are only small phase shifts instead of a series of related functions of photon numbers in the process of interaction with Kerr nonlinearities. In the absence of decoherence we analyze the error probabilities induced by homodyne measurement and show that the maximal error probability can be made small enough even when the number of photons is large. This implies that the present scheme is quite tractable and it is possible to produce entangled states involving a large number of photons.

  9. Exploration of multiphoton entangled states by using weak nonlinearities

    PubMed Central

    He, Ying-Qiu; Ding, Dong; Yan, Feng-Li; Gao, Ting

    2016-01-01

    We propose a fruitful scheme for exploring multiphoton entangled states based on linear optics and weak nonlinearities. Compared with the previous schemes the present method is more feasible because there are only small phase shifts instead of a series of related functions of photon numbers in the process of interaction with Kerr nonlinearities. In the absence of decoherence we analyze the error probabilities induced by homodyne measurement and show that the maximal error probability can be made small enough even when the number of photons is large. This implies that the present scheme is quite tractable and it is possible to produce entangled states involving a large number of photons. PMID:26751044

  10. Quantum Radiation Reaction Effects in Multiphoton Compton Scattering

    SciTech Connect

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

    2010-11-26

    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.

  11. [Gender differences in dissociative disorders].

    PubMed

    Spitzer, C; Freyberger, H J

    2008-01-01

    The relationship between mental illness, on the one hand, and sex and gender, on the other hand, has received interest since the beginning of medicine in antique times. A prototypical example of a seemingly woman-specific disease is hysteria. The term itself, which is derived from the Greek word for womb, denotes a psychosexual dimension comprising the current attitude towards sexuality and the dominating gender relationship. In addition, the colourful history of hysteria indicates that illness is not exclusively determined by biological factors, but also significantly by socio-cultural influences, for example in the treatment of hysterical women. Even nowadays, there is a wide-spread belief that dissociative symptoms and disorders, which have succeeded hysteria in current classification systems, are predominantly seen in women. However, empirical studies in the general population and in different clinical samples using sound instruments have indicated that dissociative symptoms do not differ between the genders. The seemingly dominance of dissociative disorders in women may also depend on the socio-cultural context, because men with dissociative disorders usually do not enter the general health system, but rather the legal system, i.e. they can be found in jail or forensic institutions. PMID:18185968

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

    NASA Astrophysics Data System (ADS)

    Tkaczyk, Eric Robert

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

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

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua

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

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

    NASA Astrophysics Data System (ADS)

    Skala, Melissa Caroline

    2007-12-01

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

  15. Low cost laser system generating 26-fs pulse duration, 30-kW peak power, and tunability from 800 to 1200 nm for multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Resan, Bojan; Brunner, Felix; Rohrbacher, Andreas; Ammann, Hubert; Weingarten, Kurt J.

    2012-03-01

    We demonstrate a novel low-cost, low-noise, tunable, high-peak-power, ultrafast laser system based on a SESAMmodelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression. The spectral selection, tuning, and pulse compression are performed with a simple prism compressor. The spectral broadening and fiber parameters are chosen to insure low-noise and short pulse operation of the tunable output. The long-term stable output pulses are tunable from 800 to 1200 nm, with a peak power up to 30 kW and pulse duration down to 26 fs. We demonstrate the generation of an output beam with 30 fs pulsewidth and multiple colors in infrared. In particular, we compressed selected spectral slices centered at 960 and 1100 nm suitable for imaging with green fluorescent protein and red dyes. Such a multicolor, 30 fs laser is ideally suited for simultaneous multispectral multiphoton imaging. This system is attractive for variety of applications including multiphoton (TPE, SHG, THG, CARS) and multimodal microscopy, nanosurgery, and optical coherence tomography (OCT). Such system is simpler, lower-cost, and much easier to use (fully turn-key) compared to a currently available solutions for near-infrared ultrashort pulses, typically a Ti:sapphire laser-pumped OPO.

  16. Multibeam multifocal multiphoton photon counting imaging in scattering media

    NASA Astrophysics Data System (ADS)

    Hoover, Erich E.

    Multiphoton microscopy is an invaluable technique for the neurological community, allowing for deep explorations within highly scattering tissues such as the brain. However, prior to this research multiphoton microscopy was limited in its ability to rapidly construct volumetric images deep within scattering specimens. This work establishes a technique that permits such exploration through the application of multiple beams separated in both space and time, where signal photons corresponding to those beams are demultiplexed through the use of a field programmable gate array. With this system a number of improvements are provided to research in scattering media, including the coveted ability to perform photon-counting imaging with multiple beams. The ability to perform these measurements with multiple beams permits unique quantitative measurements of fluorophores within living specimens, allowing new research into dynamic three-dimensional behavior occurring within the brain. Additionally, the ability to perform multimodal measurements without filtering allows for unique avenues of research where the harmonic generation is indistinguishable from the two-photon excited fluorescence. These improvements provide neuroscience researchers with a large assortment of technological tools that will permit them to perform numerous novel experiments within the brain and other highly-scattering specimens, which should one day lead to significant advances in our understanding of complex neuronal activity.

  17. Resonant enhanced multiphoton ionization studies of atomic oxygen

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  18. Rigid and high NA multiphoton fluorescence GRIN-endoscopes

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

  19. Multiphoton Microscopy of Nonfluorescent Nanoparticles In Vitro and In Vivo.

    PubMed

    Dietzel, Steffen; Hermann, Stefanie; Kugel, Yan; Sellner, Sabine; Uhl, Bernd; Hirn, Stephanie; Krombach, Fritz; Rehberg, Markus

    2016-06-01

    Nanotechnology holds great promise for a plethora of potential applications. The interaction of engineered nanomaterials with living cells, tissues, and organisms is, however, only partly understood. Microscopic investigations of nano-bio interactions are mostly performed with a few model nanoparticles (NPs) which are easy to visualize, such as fluorescent quantum dots. Here the possibility to visualize nonfluorescent NPs with multiphoton excitation is investigated. Signals from silver (Ag), titanium dioxide (TiO2 ), and silica (SiO2 ) NPs in nonbiological environments are characterized to determine signal dependency on excitation wavelength and intensity as well as their signal stability over time. Ag NPs generate plasmon-induced luminescence decaying over time. TiO2 NPs induce photoluminescent signals of variable intensities and in addition strong third harmonic generation (THG). Optimal settings for microscopic detection are determined and then applied for visualization of these two particle types in living cells, in murine muscle tissue, and in the murine blood stream. Silica NPs produce a THG signal, but in living cells it cannot be discriminated sufficiently from endogenous cellular structures. It is concluded that multiphoton excitation is a viable option for studies of nano-bio interactions not only for fluorescent but also for some types of nonfluorescent NPs. PMID:27120195

  20. Spectral-resolved multifocal multiphoton microscopy with multianode photomultiplier tubes

    PubMed Central

    Cha, Jae Won; Tzeranis, Dimitrios; Subramanian, Jaichandar; Yannas, Ioannis V.; Nedivi, Elly; So, Peter T. C.

    2014-01-01

    Multiphoton excitation fluorescence microscopy is the preferred method for in vivo deep tissue imaging. Many biological applications demand both high imaging speed and the ability to resolve multiple fluorophores. One of the successful methods to improve imaging speed in a highly turbid specimen is multifocal multiphoton microscopy (MMM) based on use of multi-anode photomultiplier tubes (MAPMT). This approach improves imaging speed by using multiple foci for parallelized excitation without sacrificing signal to noise ratio (SNR) due to the scattering of emission photons. In this work, we demonstrate that the MAPMT based MMM can be extended with spectral resolved imaging capability. Instead of generating multiple excitation foci in a 2D grid pattern, a linear array of foci is generated. This leaves one axis of the 2D MAPMT available for spectral dispersion and detection. The spectral-resolved MMM can detect several emission signals simultaneously with high imaging speed optimized for high-throughput, high-contents applications. The new procedure is illustrated using imaging data from the kidney, peripheral nerve regeneration and dendritic morphological data from the brain. PMID:25321515

  1. Multiphoton imaging: a view to understanding sulfur mustard lesions

    NASA Astrophysics Data System (ADS)

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

    2003-07-01

    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 μM 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 α6β4-integrin and laminin-5. At 1 h postexposure, there was disruption in the surface organization of α6β4 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  3. Two-temperature models for nitrogen dissociation

    NASA Astrophysics Data System (ADS)

    da Silva, M. Lino; Guerra, V.; Loureiro, J.

    2007-12-01

    Accurate sets of nitrogen state-resolved dissociation rates have been reduced to two-temperature (translational T and vibrational Tv) dissociation rates. The analysis of such two-temperature dissociation rates shows evidence of two different dissociation behaviors. For Tv < 0.3 T dissociation proceeds predominantly from the lower-lying vibrational levels, whereas for Tv > 0.3 T dissociation proceeds predominantly form the near-dissociative vibrational levels, with an abrupt change of behavior at Tv = 0.3 T. These two-temperature sets have then been utilized as a benchmark for the comparison against popular multitemperature dissociation models (Park, Hansen, Marrone-Treanor, Hammerling, Losev-Shatalov, Gordiets, Kuznetsov, and Macheret-Fridman). This has allowed verifying the accuracy of each theoretical model, and additionally proposing adequate values for any semi-empirical parameters present in the different theories. The Macheret-Fridman model, who acknowledges the existence of the two aforementioned dissociation regimes, has been found to provide significantly more accurate results than the other models. Although these different theoretical approaches have been tested and validated solely for nitrogen dissociation processes, it is reasonable to expect that the general conclusions of this work, regarding the adequacy of the different dissociation models, could be extended to the description of arbitrary diatomic dissociation processes.

  4. Study of the dissociation of molecular hydrogen

    NASA Technical Reports Server (NTRS)

    Vessot, R. F. C.

    1981-01-01

    Dissociators used to obtain an RF plasma discharge for hydrogen masers and the test system used for operation and evaluation of the dissociators are described. A compact sorption cartridge using a graphite matrix is tested as part of a hydrogen scavenging system. Testing of a vacuum enclosed hydrogen dissociator suitable for long term operation in space is described.

  5. Water-Soluble Quantum Dots for Multiphoton Fluorescence Imaging in Vivo

    NASA Astrophysics Data System (ADS)

    Larson, Daniel R.; Zipfel, Warren R.; Williams, Rebecca M.; Clark, Stephen W.; Bruchez, Marcel P.; Wise, Frank W.; Webb, Watt W.

    2003-05-01

    The use of semiconductor nanocrystals (quantum dots) as fluorescent labels for multiphoton microscopy enables multicolor imaging in demanding biological environments such as living tissue. We characterized water-soluble cadmium selenide-zinc sulfide quantum dots for multiphoton imaging in live animals. These fluorescent probes have two-photon action cross sections as high as 47,000 Goeppert-Mayer units, by far the largest of any label used in multiphoton microscopy. We visualized quantum dots dynamically through the skin of living mice, in capillaries hundreds of micrometers deep. We found no evidence of blinking (fluorescence intermittency) in solution on nanosecond to millisecond time scales.

  6. Water-soluble quantum dots for multiphoton fluorescence imaging in vivo.

    PubMed

    Larson, Daniel R; Zipfel, Warren R; Williams, Rebecca M; Clark, Stephen W; Bruchez, Marcel P; Wise, Frank W; Webb, Watt W

    2003-05-30

    The use of semiconductor nanocrystals (quantum dots) as fluorescent labels for multiphoton microscopy enables multicolor imaging in demanding biological environments such as living tissue. We characterized water-soluble cadmium selenide-zinc sulfide quantum dots for multiphoton imaging in live animals. These fluorescent probes have two-photon action cross sections as high as 47,000 Goeppert-Mayer units, by far the largest of any label used in multiphoton microscopy. We visualized quantum dots dynamically through the skin of living mice, in capillaries hundreds of micrometers deep. We found no evidence of blinking (fluorescence intermittency) in solution on nanosecond to millisecond time scales. PMID:12775841

  7. Multi-photon absorption in the channeling of electrons in an external field

    NASA Astrophysics Data System (ADS)

    Yaralov, V.

    2016-07-01

    Following the methods developed for atom ionization by alternating electric field the probability of multi-photon absorption of photons of the strong external laser field by channeled electron (extraction of electron from the channel) have been calculated for different strengths of the monochromatic external field. The emission spectra of 54 MeV electron channeled in diamond crystal planes (110) are shown for different values of the resonant laser field of a frequency close to the transition frequency in the channel taking into account multi-photon absorption. It is shown that the multi-photon phenomena give some contribution to the total level width.

  8. Generating Nanostructures with Multiphoton Absorption Polymerization using Optical Trap Assisted Nanopatterning

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Cheng; Leitz, Karl-Heinz; Fardel, Romain; Schmidt, Michael; Arnold, Craig B.

    The need to generate sub 100 nm features is of interest for a variety of applications including optics, optoelectronics, and plasmonics. To address this requirement, several advanced optical lithography techniques have been developed based on either multiphoton absorption polymerization or near-field effects. In this paper, we combine strengths from multiphoton absorption and near field using optical trap assisted nanopatterning (OTAN). A Gaussian beam is used to position a microsphere in a polymer precursor fluid near a substrate. An ultrafast laser is focused by that microsphere to induce multiphoton polymerization in the near field, leading additive direct-write nanoscale processing.

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

    SciTech Connect

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

    2006-07-21

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

  10. Multiphoton imaging with a novel compact diode-pumped Ti:sapphire oscillator.

    PubMed

    König, Karsten; Andersen, Peter; Le, Tuan; Breunig, Hans Georg

    2015-12-01

    Multiphoton laser scanning microscopy commonly relies on bulky and expensive femtosecond lasers. We integrated a novel minimal-footprint Ti:sapphire oscillator, pumped by a frequency-doubled distributed Bragg reflector tapered diode laser, into a clinical multiphoton tomograph and evaluated its imaging capability using different biological samples, i.e. cell monolayers, corneal tissue, and human skin. With the novel laser, the realization of very compact Ti:sapphire-based systems for high-quality multiphoton imaging at a significantly size and weight compared to current systems will become possible. PMID:26534831

  11. Infrared Investigations.

    ERIC Educational Resources Information Center

    Lascours, Jean; Albe, Virginie

    2001-01-01

    Describes a series of simple and nontraditional experiments that enable students to discover the properties of infrared radiation by studying the propagation, reflection, diffusion, and refraction of infrared. The experiments rely on two modules, an infrared transmitter and an infrared receiver. (SAH)

  12. Coulomb dissociation of N,2120

    NASA Astrophysics Data System (ADS)

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

    2016-06-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

  13. [Prison psychosis and dissociative disorders].

    PubMed

    al Chaabani, S; Bataille, M

    2002-12-01

    Through a few clinical case histories stemming from their daily activities at the psychiatric section of the Lantin Prison, the authors propose to revisit the classic concept of Prison psychosis. They broaden its limits to include other psychotic and dissociative phenomena common to the jail population. This requires a strict differential diagnosis, allowing to eliminate some similar pathologies; nevertheless, some difficulties and imperfections persist. The development of the psychosis, the input from the jail architecture and milieu, the predisposing as well as facilitating factors linked to the personality of the inmate, and triggering phenomena are discussed. Finally, the comorbidity between these psychotic/dissociative phenomena and the borderline & histrionic personality disorders is envisaged. PMID:12632838

  14. [Dis-social personality disorder].

    PubMed

    Habermeyer, E; Herpertz, S C

    2006-05-01

    Deviant behavior is gaining in clinical importance if it is founded on stable, characteristic, and enduring patterns of psychopathologically relevant personality traits which have their onset in childhood or adolescence. The classification of these traits shows variations, so that a distinction between the ICD-10 diagnosis of dis-social personality disorder, DSM-IV diagnosis of antisocial personality disorder, and the concept "psychopathy" is necessary. Our knowledge about the biological basis of antisocial behavior includes neurophysiologic, psychophysiologic, and genetic findings. Also relevant are results of neurotransmitter studies and structural resp. functional neuroimaging findings. Psychosocial risk factors include parental deficits, rejection, disregard, unstable relations, and abuse. Efficient psychotherapeutic treatment is cognitive-behavioral. Pharmacologic treatment is largely "off-label". The diagnosis of antisocial and dis-social personality disorders allows no conclusions on criminal responsibility. In addition to psychiatric diagnostics, considerations on the severity of the disorder and its effects on the ability to inhibit actions are necessary. PMID:16609871

  15. Population inversion of molecular nitrogen in an Ar: N2 mixture by selective resonance-enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Shneider, M. N.; Baltuška, A.; Zheltikov, A. M.

    2011-10-01

    Resonance-enhanced multiphoton ionization (REMPI) is shown to offer an attractive strategy for population inversion of molecular nitrogen in an Ar: N2 gas mixture. We present a detailed analysis of the key processes leading to a population inversion of molecular nitrogen in a REMPI-pumped Ar: N2 gas mixture, including a (3 + 1) REMPI of argon atoms, conversion of the REMPI-generated atomic argon ions into molecular ions, and generation of long-lived metastable excited-state argon atoms through dissociative recombination, populating the C3πu states of molecular nitrogen. Population inversion achieved for the second-positive-band laser transitions of molecular nitrogen enables stimulated emission of ultraviolet radiation at 337 nm. A high selectivity of the REMPI process helps to radically reduce the depletion of the working medium through the ionization of N2, providing a pump mechanism that is ideally suited for the creation of a new type of a highly efficient nitrogen laser.

  16. Dissociative recombination of rotationally cold H+3

    NASA Astrophysics Data System (ADS)

    McCall, B. J.; Huneycutt, A. J.; Saykally, R. J.; Djuric, N.; Dunn, G. H.; Semaniak, J.; Novotny, O.; Al-Khalili, A.; Ehlerding, A.; Hellberg, F.; Kalhori, S.; Neau, A.; Thomas, R. D.; Paal, A.; Österdahl, F.; Larsson, M.

    2004-11-01

    This paper presents the first dissociative recombination (DR) measurement of electrons with rotationally and vibrationally cold H+3 ions. A dc discharge pinhole supersonic jet source was developed and characterized using infrared cavity ringdown spectroscopy before installation on the CRYRING ion storage ring for the DR measurements. Rotational state distributions ( Trot ˜30 K ) produced using the source were comparable to those in the diffuse interstellar medium. Our measurement of the electron energy dependence of the DR cross section showed resonances not clearly seen in experiments using rotationally hot ions, and allowed calculation of the thermal DR rate coefficient for ions at interstellar temperatures, αDR (23 K)=2.6× 10-7 cm3 s-1 . This value is in general agreement with recent theoretical predictions by

    Kokoouline and Greene [Phys. Rev. A 68, 012703 (2003)
    ]. The branching fractions of the two breakup channels, H+H+H and H+ H2 , have also been measured for rotationally and vibrationally cold H+3 .

  17. [Clinical Handling of Patients with Dissociative Disorders].

    PubMed

    Okano, Kenichiro

    2015-01-01

    This paper discusses the way informed psychiatrists are expected to handle dissociative patients in clinical situations, with a specific focus on dissociative identity disorders and dissociative fugue. On the initial interview with dissociative patients, information on their history of trauma and any nascent dissociative symptoms in their childhood should be carefully obtained. Their level of stress in their current life should also be assessed in order to understand their symptomatology, as well as to predict their future clinical course. A psychoeducational approach is crucial; it might be helpful to give information on dissociative disorder to these patients as well as their family members in order to promote their adherence to treatment. Regarding the symptomatology of dissociative disorders, detailed symptoms and the general clinical course are presented. It was stressed that dissociative identity disorder and dissociative fugue, the most high-profile dissociative disorders, are essentially different in their etiology and clinical presentation. Dissociative disorders are often confused with and misdiagnosed as psychotic disorders, such as schizophrenia. Other conditions considered in terms of the differential diagnosis include borderline personality disorder as well as temporal lobe epilepsy. Lastly, the therapeutic approach to dissociative identity disorder is discussed. Each dissociative identity should be understood as potentially representing some traumatically stressful event in the past. The therapist should be careful not to excessively promote the creation or elaboration of any dissociative identities. Three stages are proposed in the individual psychotherapeutic process. In the initial stage, a secure environment and stabilization of symptoms should be sought. The second stage consists of aiding the "host" personality to make use of other more adaptive coping skills in their life. The third stage involves coaching as well as continuous awareness of

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

    PubMed Central

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

    2009-01-01

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

  19. Multiphoton FLIM: a reliable FRET detection tool in cell biological applications

    NASA Astrophysics Data System (ADS)

    Krishnan, Ramanujan V.; Biener, Eva; Centonze, Victoria E.; Gertler, Arieh; Herman, Brian A.

    2004-06-01

    Fluorescence lifetime imaging microscopy (FLIM) using multiphoton excitation is emerging as a reliable quantitative tool for measuring fluorescence resonance energy transfer (FRET) in living cells. By virtue of being free from spectroscopic artifacts encountered in conventional FRET detection methods, multiphoton FLIM methods offer the advantages of high spatial and temporal resolution, faster data acquisition and data analysis. We compare the FRET results obtained by two different methods namely (i) multiphoton excitation lifetime-based FRET and (ii) single photon excitation intensity-based acceptor photobleaching FRET. Using the same biological samples, we apply these two different methods in understanding the growth hormone receptor dimerization kinetics at the cell surface of human embryonic kidney cells. We conclude that the multiphoton FLIM using the streak-camera approach provides the best ability to monitor FRET in dynamic situations where high temporal and spatial resolution are required with minimal photodamage/phototoxicity.

  20. Multiphoton Processes: ICOMP VIII: 8th International Conference, AIP Conference Proceedings, No. 525 [APCPCS

    SciTech Connect

    DiMauro, L.F.; Freeman, R.R.; Kulander, K.C.

    2000-12-31

    Topics include: atoms in strong fields; stabilization; double ionization and multi-electron calculations; high-order harmonics; molecules in strong fields; multiphoton processes in clusters; coherent control; light sources; and relativistic effects.

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

    PubMed Central

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

    2013-01-01

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

  2. Clinical multiphoton tomography and clinical two-photon microendoscopy

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  4. Multiphoton-state-assisted entanglement purification of material qubits

    NASA Astrophysics Data System (ADS)

    Bernád, József Zsolt; Torres, Juan Mauricio; Kunz, Ludwig; Alber, Gernot

    2016-03-01

    We propose an entanglement purification scheme based on material qubits and ancillary coherent multiphoton states. We consider a typical QED scenario where material qubits implemented by two-level atoms fly sequentially through a cavity and interact resonantly with a single mode of the radiation field. We explore the theoretical possibilities of realizing a high-fidelity two-qubit quantum operation necessary for the purification protocol with the help of a postselective balanced homodyne photodetection. We demonstrate that the obtained probabilistic quantum operation can be used as a bilateral operation in the proposed purification scheme. It is shown that the probabilistic nature of this quantum operation is counterbalanced in the last step of the scheme where qubits are not discarded after inadequate qubit measurements. As this protocol requires present-day experimental setups and generates high-fidelity entangled pairs with high repetition rates, it may offer interesting perspectives for applications in quantum information theory.

  5. Molecule-specific darkfield and multiphoton imaging using gold nanocages

    NASA Astrophysics Data System (ADS)

    Powless, Amy J.; Jenkins, Samir V.; McKay, Mary Lee; Chen, Jingyi; Muldoon, Timothy J.

    2015-03-01

    Due to their robust optical properties, biological inertness, and readily adjustable surface chemistry, gold nanostructures have been demonstrated as contrast agents in a variety of biomedical imaging applications. One application is dynamic imaging of live cells using bioconjugated gold nanoparticles to monitor molecule trafficking mechanisms within cells; for instance, the regulatory pathway of epidermal growth factor receptor (EGFR) undergoing endocytosis. In this paper, we have demonstrated a method to track endocytosis of EGFR in MDA-MB-468 breast adenocarcinoma cells using bioconjugated gold nanocages (AuNCs) and multiphoton microscopy. Dynamic imaging was performed using a time series capture of 4 images every minute for one hour. Specific binding and internalization of the bioconjugated AuNCs was observed while the two control groups showed non-specific binding at fewer surface sites, leading to fewer bound AuNCs and no internalization.

  6. Wavefront sensorless adaptive optics temporal focusing-based multiphoton microscopy

    PubMed Central

    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

    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 1μm fluorescent beads sealed in agarose gel at different depths is improved. PMID:24940539

  7. Multiphoton Microscopy and Interaction of Intense Light Pulses with Polymers

    NASA Astrophysics Data System (ADS)

    Guay, Jean-Michel

    2011-07-01

    The nanoscale manipulation of soft-matter, such as biological tissues, in its native environment has promising applications in medicine to correct for defects (eg. eye cataracts) or to destroy malignant regions (eg. cancerous tumours). To achieve this we need the ability to first image and then do precise ablation with sub-micron resolution with the same setup. For this purpose, we designed and built a multiphoton microscope and tested it on goldfish gills and bovine cells. We then studied light-matter interaction on a hard polymer (PMMA) because the nature of ablation of soft-matter in its native environment is complex and not well understood. Ablation and modification thresholds for successive laser shots were obtained. The ablation craters revealed 3D nanostructures and polarization dependent orientation. The interaction also induced localized porosity in PMMA that can be controlled.

  8. Guided Homing of Cells in Multi-Photon Microfabricated Bioscaffolds.

    PubMed

    Skylar-Scott, Mark A; Liu, Man-Chi; Wu, Yuelong; Dixit, Atray; Yanik, Mehmet Fatih

    2016-05-01

    Tissues contain exquisite vascular microstructures, and patterns of chemical cues for directing cell migration, homing, and differentiation for organ development and function. 3D microfabrication by multi-photon photolithography is a flexible, high-resolution tool for generating 3D bioscaffolds. However, the combined fabrication of scaffold microstructure simultaneously with patterning of cues to create both geometrically and chemically defined microenvironments remains to be demonstrated. This study presents a high-speed method for micron-resolution fabrication of scaffold microstructure and patterning of protein cues simultaneously using native scaffold materials. By the simultaneous microfabrication of arbitrary microvasculature geometries, and patterning selected regions of the microvasculature with the homing ligand P-selectin, this study demonstrates adhesion, rolling, and selective homing of cells in defined 3D regions. This novel ability to generate high-resolution geometries replete with patterned cues at high speed enables the construction of biomimetic microenvironments for complex 3D assays of cellular behavior. PMID:27059425

  9. Reassignment of scattered emission photons in multifocal multiphoton microscopy.

    PubMed

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

    2014-01-01

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

  10. Theory of multiphoton and tunnel ionization in a bichromatic field

    SciTech Connect

    Bagulov, D. S.; Kotelnikov, I. A.

    2013-01-15

    The imaginary-time method [6, 7] is used to calculate the multiphoton and tunnel ionization probabilities for atoms in a laser radiation field part of which is converted into the second harmonic. We assume that the first harmonic has a linear or elliptical polarization and the second harmonic is polarized linearly, with its polarization vector making an arbitrary angle with that of the first harmonic. The mean momentum of the photoelectrons knocked out from atoms is shown to depend on the phase shift between the first and second harmonics and their mutual polarization and to be identically equal to zero for a monochromatic field. An important difference between the case of elliptical polarization and the case of linear polarization of both harmonics is the absence of conditions under which the conditions for dominance of one of the two generation mechanisms considered here can be identified during the generation of terahertz radiation from the region of optical breakdown in a gas.

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

    PubMed Central

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

    2015-01-01

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

  12. Monitoring wound healing by multiphoton tomography/endoscopy

    NASA Astrophysics Data System (ADS)

    König, Karsten; Weinigel, Martin; Bückle, Rainer; Kaatz, Martin; Hipler, Christina; Zens, Katharina; Schneider, Stefan W.; Huck, Volker

    2015-02-01

    Certified clinical multiphoton tomographs are employed to perform rapid label-free high-resolution in vivo histology. Novel tomographs include a flexible 360° scan head attached to a mechano-optical arm for autofluorescence and SHG imaging as well as rigid two-photon GRIN microendoscope. Mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged with submicron resolution in human skin. The system was employed to study the healing of chronic wounds (venous leg ulcer) and acute wounds (curettage of actinic or seborrheic keratosis) on a subcellular level. Furthermore, a flexible sterile foil as interface between wound and focusing optic was tested.

  13. Reassignment of Scattered Emission Photons in Multifocal Multiphoton Microscopy

    PubMed Central

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

    2014-01-01

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

  14. Multiphoton quantum Rabi oscillations in ultrastrong cavity QED

    NASA Astrophysics Data System (ADS)

    Garziano, Luigi; Stassi, Roberto; Macrı, Vincenzo; Kockum, Anton Frisk; Savasta, Salvatore; Nori, Franco

    2015-12-01

    When an atom is strongly coupled to a cavity, the two systems can exchange a single photon through a coherent Rabi oscillation. This process enables precise quantum-state engineering and manipulation of atoms and photons in a cavity, which play a central role in quantum information and measurement. Recently, a new regime of cavity QED was reached experimentally where the strength of the interaction between light and artificial atoms (qubits) becomes comparable to the atomic transition frequency or the resonance frequency of the cavity mode. Here we show that this regime can strongly modify the concept of vacuum Rabi oscillations, enabling multiphoton exchanges between the qubit and the resonator. We find that experimental state-of-the-art circuit-QED systems can undergo two- and three-photon vacuum Rabi oscillations. These anomalous Rabi oscillations can be exploited for the realization of efficient Fock-state sources of light and complex entangled states of qubits.

  15. Reassignment of Scattered Emission Photons in Multifocal Multiphoton Microscopy

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Multifocal multiphoton microscopy (MMM) achieves fast imaging by simultaneously scanning multiple foci across different regions of specimen. The use of imaging detectors in MMM, such as CCD or CMOS, results in degradation of image signal-to-noise-ratio (SNR) due to the scattering of emitted photons. SNR can be partly recovered using multianode photomultiplier tubes (MAPMT). In this design, however, emission photons scattered to neighbor anodes are encoded by the foci scan location resulting in ghost images. The crosstalk between different anodes is currently measured a priori, which is cumbersome as it depends specimen properties. Here, we present the photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, for quantification of crosstalk between the anodes of MAPMT without a priori measurement. The method provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image.

  16. Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy.

    PubMed

    Antonello, Jacopo; van Werkhoven, Tim; Verhaegen, Michel; Truong, Hoa H; Keller, Christoph U; Gerritsen, Hans C

    2014-06-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration. PMID:24977374

  17. Multiphoton intravital microscopy setup to visualize the mouse mammary gland

    NASA Astrophysics Data System (ADS)

    Adur, Javier; Herrera Torres, Ana M.; Masedunskas, Andrius; Baratti, Mariana O.; de Thomaz, Andre A.; Pelegati, Vitor B.; Carvalho, Hernandes F.; Cesar, Carlos L.

    2013-06-01

    Recently, light microscopy-based techniques have been extended to live mammalian models leading to the development of a new imaging approach called intravital microscopy (IVM). Although IVM has been introduced at the beginning of the last century, its major advancements have occurred in the last twenty years with the development of non-linear microscopy that has enabled performing deep tissue imaging. IVM has been utilized to address many biological questions in basic research and is now a fundamental tool that provide information on tissues such as morphology, cellular architecture, and metabolic status. IVM has become an indispensable tool in numerous areas. This study presents and describes the practical aspects of IVM necessary to visualize epithelial cells of live mouse mammary gland with multiphoton techniques.

  18. High-Resolution Multiphoton Imaging of Tumors In Vivo

    PubMed Central

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

    2014-01-01

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

  19. Multiphoton ionization and third-harmonic generation in atoms and molecules

    SciTech Connect

    Compton, R.N.

    1982-01-01

    Resonantly enhanced multiphoton ionization (REMPI) provides a powerful new method for investigating atomic and molecular energy levels. The method is particularly useful in discovering and characterizing certain optically forbidden transitions. The method is particularly well suited for studying Rydberg transitions in molecules and is experimentally easier than the traditional use of far ultraviolet radiation in conventional spectroscopy. Research on multiphoton ionization and third-harmonic generation is reviewed. (WHK)

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  1. Multiphoton fluorescence microscopy of the live kidney in health and disease.

    PubMed

    Small, David M; Sanchez, Washington Y; Roy, Sandrine; Hickey, Michael J; Gobe, Glenda C

    2014-02-01

    The structural and functional heterogeneity of the kidney ensures a diversity of response in health and disease. Multiphoton microscopy has improved our understanding of kidney physiology and pathophysiology by enabling the visualization of the living kidney in comparison with the static view of previous technologies. The use of multiphoton microscopy with rodent models in conjunction with endogenous fluorescence and exogenous infused dyes permits the measurement of renal processes, such as glomerular permeability, juxtaglomerular apparatus function, tubulointerstitial function, tubulovascular interactions, vascular flow rate, and the intrarenal renin-angiotensin-aldosterone system. Subcellular processes, including mitochondrial dynamics, reactive oxygen species production, cytosolic ion concentrations, and death processes apoptosis and necrosis, can also be measured by multiphoton microscopy. This has allowed valuable insight into the pathophysiology of diabetic nephropathy, renal ischemia-reperfusion injury, hypertensive nephropathy, as well as inflammatory responses of the kidney. The current review presents an overview of multiphoton microscopy with a focus on techniques for imaging the kidney and gives examples of instances where multiphoton microscopy has been utilized to study renal pathophysiology in the living kidney. With continued advancements in the field of biological optics and increased adoption in experimental nephrology, multiphoton microscopy will undoubtedly continue to create new paradigms in kidney disease. PMID:24525825

  2. Ultraviolet photolysis of adenine: Dissociation via the {sup 1}{pi}{sigma}{sup *} state

    SciTech Connect

    Nix, Michael G. D.; Devine, Adam L.; Cronin, Brid; Ashfold, Michael N. R.

    2007-03-28

    High resolution total kinetic energy release (TKER) spectra of the H atom fragments resulting from photodissociation of jet-cooled adenine molecules at 17 wavelengths in the range 280>{lambda}{sub phot}>214 nm are reported. TKER spectra obtained at {lambda}{sub phot}>233 nm display broad, isotropic profiles that peak at low TKER ({approx}1800 cm{sup -1}) and are largely insensitive to the choice of excitation wavelength. The bulk of these products is attributed to unintended multiphoton dissociation processes. TKER spectra recorded at {lambda}{sub phot}{<=}233 nm display additional fast structure, which is attributed to N{sub 9}-H bond fission on the {sup 1}{pi}{sigma}{sup *} potential energy surface (PES). Analysis of the kinetic energies and recoil anisotropies of the H atoms responsible for the fast structure suggests excitation to two {sup 1}{pi}{pi}{sup *} excited states (the {sup 1}L{sub a} and {sup 1}B{sub b} states) at {lambda}{sub phot}{approx}230 nm, both of which dissociate to yield H atoms together with ground state adeninyl fragments by radiationless transfer through conical intersections with the {sup 1}{pi}{sigma}{sup *} PES. Parallels with the photochemistry exhibited by other, smaller heteroaromatics (pyrrole, imidazole, phenol, etc.) are highlighted, as are inconsistencies between the present conclusions and those reached in two other recent studies of excited state adenine molecules.

  3. Religious Dissociation and Economic Appraisal in Brazil.

    PubMed

    François Dengah, H J

    2016-04-01

    Research on the association between religion and health often neglects to provide an explicit theoretical mechanism of influence between faith and well-being. This research posits that dissociative behaviors, such as glossolalia, may provide a biological pathway that influences both physiological and psychological health. This paper argues that religious dissociation acts as a moderator between economic stressors and psychobiological appraisal. Brazil, with its economic inequality and preponderance of religious dissociative rituals, provides an ideal context to examine religious dissociation as a moderator of stress. Utilizing data from a cross section of Brazilian faiths, this paper examines: (1) Whether individuals with low socioeconomic status preferentially participate and experience religious dissociative states and (2) whether dissociative states are correlated with greater psychological appraisal of status. PMID:25687180

  4. Dissociative Tendencies and Facilitated Emotional Processing

    PubMed Central

    Oathes, Desmond J.; Ray, William J.

    2009-01-01

    Dissociation is a process linked to lapses of attention, history of abuse or trauma, compromised emotional memory, and a disintegrated sense of self. It is theorized that dissociation stems from avoiding emotional information, especially negative emotion, to protect a fragile psyche. The present study tested whether or not dissociaters do actually avoid processing emotion by asking groups scoring high or low on the Dissociative Experiences Scale to judge the affective valence of several types of emotional stimuli. Manipulations of valence, modality (pictures or words), task complexity, and personal relevance lead to results suggesting that dissociation is linked to facilitated rather than deficient emotional processing. Our results are consistent with a theory that sensitivity to emotional material may be a contributing factor in subsequent dissociation to avoid further elaboration of upsetting emotion in these individuals. The findings for dissociation further exemplify the influence of individual differences in the link between cognition and emotion. PMID:18837615

  5. Coulomb Dissociation of 27P

    NASA Astrophysics Data System (ADS)

    Beceiro Novo, S.; Sümmerer, K.; Cortina-Gil, D.; Wimmer, C.; Plag, R.; Alvarez-Pol, H.; Aumann, T.; Behr, K.; Boretzky, K.; Casarejos, E.; Chatillon, A.; Datta-Pramanik, U.; Elekes, Z.; Fulop, Z.; Galaviz, D.; Geissel, H.; Giron, S.; Greife, U.; Hammache, F.; Heil, M.; Hoffman, J.; Johansson, H.; Karagiannis, C.; Kiselev, O.; Kurz, N.; Larsson, K.; Le Bleis, T.; Litvinov, Y.; Mahata, K.; Muentz, C.; Nociforo, C.; Ott, W.; Paschalis, S.; Prokopowicz, W.; Rodriguez-Tajes, C.; Rossi, D.; Simon, H.; Stanoiu, M.; Stroth, J.; Typel, S.; Wagner, A.; Wamers, F.; Weick, H.

    2012-09-01

    In this work the astrophysical 26Si(p,γ)27P reaction is studied using the Coulomb dissociation technique. We performed a 27P Coulomb Dissociation experiment at GSI, Darmstadt (28 May-5 June 2007) using the ALADIN-LAND setup which allows complete-kinematic studies. A secondary 27P beam at 498 AMeV impinging a 515mg/cm2 Pb target was used. The relative energy of the outgoing system (26Si+p) is measured obtaining the resonant states of the 27P. Preliminary results show four resonant states measured at 0.36±0.07, 0.88±0.09, 1.5±0.2, 2.3±0.3 MeV and evidence of a higher state at around 3.1 MeV. The preliminary total cross section obtained for relative energies between 0 and 3 MeV has been measured and yields 55±7 mb.

  6. Dissociative recombination in planetary ionospheres

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1993-01-01

    Ionization in planetary atmospheres can be produced by solar photoionization, photoelectron impact ionization, and, in auroral regions, by impact of precipitating particles. This ionization is lost mainly in dissociative recombination (DR) of molecular ions. Although atomic ions cannot undergo DR, they can be transformed locally through ion-molecule reactions into molecular ions, or they may be transported vertically or horizontally to regions of the atmosphere where such transformations are possible. Because DR reactions tend to be very exothermic, they can be an important source of kinetically or internally excited fragments. In interplanetary thermospheres, the neutral densities decrease exponentially with altitude. Below the homopause (or turbopause), the atmosphere is assumed to be throughly mixed by convection and/or turbulence. Above the homopause, diffusion is the major transport mechanism, and each species is distributed according to its mass, with the logarithmic derivative of the density with repect to altitude given approximately by -1/H, where H = kT/mg is the scale height. In this expression, T is the neutral temperature, g is the local acceleratiion of gravity, and m is the mass of the species. Thus lighter species become relatively more abundant, and heavier species less abundant, as the altitude increases. This variation of the neutral composition can lead to changes in the ion composition; furthermore, as the neutral densities decrease, dissociative recombination becomes more important relative to ion-neutral reactions as a loss mechanism for molecular ions.

  7. Dissociative Recombination without a Curve Crossing

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1994-01-01

    Ab initio calculations show that a curve crossing is not always needed for a high dissociative- recombination cross section. For HeH(+), in which no neutral states cross the ion potential curve, dissociative recombination is driven by the nuclear kinetic-energy operator on adiabatic potential curves. The kinetic-energy derivative operator allows for capture into repulsive curves that are outside of the classical turning points for the nuclear motion. The dominant dissociative route is the C (2)Sigma(+) state leading to H(n = 2) atoms. An analogous mechanism is proposed for the dissociative recombination of H3(+).

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2015-04-01

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

  10. Degree of somatoform and psychological dissociation in dissociative disorder is correlated with reported trauma.

    PubMed

    Nijenhuis, E R; Spinhoven, P; van Dyck, R; van der Hart, O; Vanderlinden, J

    1998-10-01

    In this study, the prevalence and severity of traumatic experiences as reported by patients with dissociative disorders and with other DSM-IV psychiatric diagnoses were compared. Furthermore, the predictive value of emotional, physical, and sexual trauma with respect to somatoform and psychological dissociation was analyzed. In contrast with comparison patients, dissociative disorder patients reported severe and multifaceted traumatization. Physical and sexual trauma predicted somatoform dissociation, sexual trauma predicted psychological dissociation as well. According to the memories of the dissociative disorder patients, this abuse occurred in an emotionally neglectful and abusive social context. Pathological dissociation was best predicted by early onset of reported intense, chronic and multiple traumatization. Methodological limitations restricting causal inferences between reported trauma and dissociation are discussed. PMID:9870223

  11. Dissociative adsorption of hydrogen on the ZrB2(0001) surface

    NASA Astrophysics Data System (ADS)

    Walkosz, Weronika; Manandhar, Kedar; Trenary, Michael; Otani, Shigeki; Zapol, Peter

    2012-12-01

    We have studied the dissociation of H2 on the ZrB2(0001) surface using density functional theory and reflection absorption infrared spectroscopy (RAIRS). Our results show that H2 readily dissociates on the Zr-terminated (0001) surface up to a H coverage of 1/2 ML. Furthermore, we show that H is very mobile on the surface and that it desorbs between 545 and 625 K. The calculated vibrational frequencies for the adsorbed H are in excellent agreement with our RAIRS measurements and with previously reported high resolution electron energy loss spectra.

  12. Infrared thermography

    SciTech Connect

    Roberts, C.C. Jr.

    1982-12-01

    Infrared thermography is a useful tool for the diagnosis of problems in building systems. In instances where a building owner has several large buildings, an investment in a typical $30,000 infrared system may be cost effective. In most instances, however, the rental of an infrared system or the hiring of an infrared consulting service is a cost effective alternative. As can be seen from the several applications presented here, any mechanical problem manifesting itself in an atypical temperature pattern can usually be detected. The two primary savings generated from infrared analysis of building systems are maintenance and energy.

  13. Dissociative symptoms and dissociative disorder comorbidity in patients with obsessive-compulsive disorder.

    PubMed

    Belli, Hasan; Ural, Cenk; Vardar, Melek Kanarya; Yesılyurt, Sema; Oncu, Fatıh

    2012-10-01

    The present study attempted to assess the dissociative symptoms and overall dissociative disorder comorbidity in patients with obsessive-compulsive disorder (OCD). In addition, we examined the relationship between the severity of obsessive-compulsive symptoms and dissociative symptoms. All patients admitted for the first time to the psychiatric outpatient unit were included in the study. Seventy-eight patients had been diagnosed as having OCD during the 2-year study period. Patients had to meet the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for OCD. Most (76.9%; n = 60) of the patients were female, and 23.1% (n = 18) of the patients were male. Dissociation Questionnaire was used to measure dissociative symptoms. The Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Dissociative Disorders interviews and Yale-Brown Obsessive Compulsive Checklist and Severity Scale were used. Eleven (14%) of the patients with OCD had comorbid dissociative disorder. The most prevalent disorder in our study was dissociative depersonalization disorder. Dissociative amnesia and dissociative identity disorder were common as well. The mean Yale-Brown score was 23.37 ± 7.27 points. Dissociation Questionnaire scores were between 0.40 and 3.87 points, and the mean was 2.23 ± 0.76 points. There was a statistically significant positive correlation between Yale-Brown points and Dissociation Questionnaire points. We conclude that dissociative symptoms among patients with OCD should alert clinicians for the presence of a chronic and complex dissociative disorder. Clinicians may overlook an underlying dissociative process in patients who have severe symptoms of OCD. However, a lack of adequate response to cognitive-behavioral and drug therapy may be a consequence of dissociative process. PMID:22425531

  14. Infrared laser photolysis - A new tool for the study of prebiotic chemistry

    NASA Technical Reports Server (NTRS)

    Davis, D. D.; Smith, G. R.; Guillory, W. A.

    1980-01-01

    Infrared laser induced dielectric breakdown and multiphoton absorption experiments on CH4/NH3 'atmospheres' are described. It is found that HCN, a central intermediate in prebiotic chemistry, is a principal product. This, combined with the fact that dielectric breakdown appears to have much in common with ordinary electric sparks, suggests that the laser could be a useful tool in studies of prebiotic chemistry. Several possible experiments in this vein are suggested.

  15. Molecular dissociation in dilute gas

    SciTech Connect

    Renfrow, S.N.; Duggan, J.L.; McDaniel, F.D. |

    1999-06-01

    The charge state distributions (CSD) produced during molecular dissociation are important to both Trace Element Accelerator Mass Spectrometry (TEAMS) and the ion implantation industry. The CSD of 1.3{endash}1.7 MeV SiN{sup +}, SiMg{sup +}, SiMn{sup +}, and SiZn{sup +} molecules have been measured for elements that do not form atomic negative ions (N, Mg, Mn, and Zn) using a NEC Tandem Pelletron accelerator. The molecules were produced in a Cs sputter negative ion source, accelerated, magnetically analyzed, and then passed through an N{sub 2} gas cell. The neutral and charged breakups where analyzed using an electrostatic deflector and measured with particle detectors. Equilibrium CSD were determined and comparisons made between molecular and atomic ion data. {copyright} {ital 1999 American Institute of Physics.}

  16. The Dissociative Recombination of OH(+)

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1995-01-01

    Theoretical quantum chemical calculations of the cross sections and rates for the dissociative recombination of the upsilon = 0 level of the ground state of OH(+) show that recombination occurs primarily along the 2 (2)Pi diabatic route. The products are 0((1)D) and a hot H atom with 6.1 eV kinetic energy. The coupling to the resonances is very small and the indirect recombination mechanism plays only a minor role. The recommended value for the rate coefficient is (6.3 +/- 0.7) x 10(exp -9)x (T(e)/1300)(exp -0.48) cu.cm/s for 10 less than T(e) less than 1000 K.

  17. Dissociative recombination of highly symmetric polyatomic ions.

    PubMed

    Douguet, Nicolas; Orel, Ann E; Greene, Chris H; Kokoouline, Viatcheslav

    2012-01-13

    A general first-principles theory of dissociative recombination is developed for highly symmetric molecular ions and applied to H(3)O(+) and CH(3)(+), which play an important role in astrophysical, combustion, and laboratory plasma environments. The theoretical cross sections obtained for the dissociative recombination of the two ions are in good agreement with existing experimental data from storage ring experiments. PMID:22324682

  18. A Hierarchical Process-Dissociation Model

    ERIC Educational Resources Information Center

    Rouder, Jeffrey N.; Lu, Jun; Morey, Richard D.; Sun, Dongchu; Speckman, Paul L.

    2008-01-01

    In fitting the process-dissociation model (L. L. Jacoby, 1991) to observed data, researchers aggregate outcomes across participant, items, or both. T. Curran and D. L. Hintzman (1995) demonstrated how biases from aggregation may lead to artifactual support for the model. The authors develop a hierarchical process-dissociation model that does not…

  19. Dissociation and the Development of Psychopathology.

    ERIC Educational Resources Information Center

    Putnam, Frank W.; Trickett, Penelope K.

    This paper reviews the research on dissociation and the development of psychopathology in children and adolescents. Definitions and dimensions of dissociation are addressed, noting its range from normative daydreaming to the extremes found in individuals with multiple personality disorder. Memory dysfunctions, disturbances of identity, passive…

  20. Dissociative depression among women in the community.

    PubMed

    Sar, Vedat; Akyüz, Gamze; Oztürk, Erdinç; Alioğlu, Firdevs

    2013-01-01

    This study screened the prevalence and correlates of dissociative disorders among depressive women in the general population. The Dissociative Disorders Interview Schedule and the posttraumatic stress disorder (PTSD) and borderline personality disorder sections of the Structured Clinical Interview for DSM-IV were administered to 628 women in 500 homes. The prevalence of current major depressive episode was 10.0%. Of the women, 26 (40.6%) had the lifetime diagnosis of a DSM-IV, dissociative disorder, yielding a prevalence of 4.1% for dissociative depression. This group was younger (mean age = 30.7 years) than the nondissociative depression women (mean age = 39.6 years). There was no difference between the 2 groups on comorbid somatization disorder, PTSD, or borderline personality disorder. Besides suicide attempts, the dissociative group was characterized by secondary features of dissociative identity disorder; Schneiderian symptoms; borderline personality disorder criteria; and extrasensory perceptions, including possession experiences. They reported suicidality, thoughts of guilt and worthlessness, diminished concentration and indecisiveness, and appetite and weight changes more frequently than the nondissociative group. Early cessation of school education and childhood sexual abuse were frequently reported by the dissociative depression group. With its distinct features, the concept of dissociative depression may facilitate understanding of treatment resistance in, development of better psychotherapy strategies for, and new thinking on the neurobiology and pharmacotherapy of depressive disorders. PMID:23796173

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

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n-mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [F. Dell'Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.

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

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n -mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [

    F. Dell’Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)
    ], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

  4. Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  5. The multiphoton ionization of uranium hexafluoride. Revision 1

    SciTech Connect

    Armstrong, D.P.

    1992-05-01

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

  6. Superresolved multiphoton microscopy with spatial frequency-modulated imaging.

    PubMed

    Field, Jeffrey J; Wernsing, Keith A; Domingue, Scott R; Allende Motz, Alyssa M; DeLuca, Keith F; Levi, Dean H; DeLuca, Jennifer G; Young, Michael D; Squier, Jeff A; Bartels, Randy A

    2016-06-14

    Superresolved far-field microscopy has emerged as a powerful tool for investigating the structure of objects with resolution well below the diffraction limit of light. Nearly all superresolution imaging techniques reported to date rely on real energy states of fluorescent molecules to circumvent the diffraction limit, preventing superresolved imaging with contrast mechanisms that occur via virtual energy states, including harmonic generation (HG). We report a superresolution technique based on spatial frequency-modulated imaging (SPIFI) that permits superresolved nonlinear microscopy with any contrast mechanism and with single-pixel detection. We show multimodal superresolved images with two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) from biological and inorganic media. Multiphoton SPIFI (MP-SPIFI) provides spatial resolution up to 2η below the diffraction limit, where η is the highest power of the nonlinear intensity response. MP-SPIFI can be used to provide enhanced resolution in optically thin media and may provide a solution for superresolved imaging deep in scattering media. PMID:27231219

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

    NASA Astrophysics Data System (ADS)

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

    2002-06-01

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

  8. Multiphoton and photothermal imaging of molecular events in cancer

    NASA Astrophysics Data System (ADS)

    Skala, Melissa

    2010-10-01

    Optical techniques are attractive for monitoring disease processes in living tissues because they are relatively cheap, non-invasive and provide a wealth of functional information. Multiphoton microscopy (MPM) and Optical Coherence Tomography (OCT) are two types of three-dimensional optical imaging modalities that have demonstrated great utility in pre-clinical models of disease. These techniques are particularly useful for identifying metabolic and molecular biomarkers in cancer. These biomarkers can be used to identify the mechanisms of tumor growth, and to predict the response of a particular tumor to treatment. Specifically, MPM of the co-enzymes NADH and FAD was used to quantify metabolic changes associated with developing cancers in vivo. This imaging technique exploits intrinsic sources of tissue contrast and thus does not require contrast agents. Ongoing work combines this metabolic imaging technique with vascular imaging to provide a comprehensive picture of oxygen supply and demand with tumor therapy. Molecular signaling represents a third critical component in tumor physiology. To this end we have recently developed photothermal OCT, which combines coherent detection with laser-heated gold nanoparticles to achieve high-resolution molecular contrast at deeper depths than MPM. This multi-functional imaging platform will provide unprecedented insight into oxygen supply and demand, and molecular signaling in response to tumor growth and targeted cancer therapies in pre-clinical models.

  9. Multiphoton imaging the disruptive nature of sulfur mustard lesions

    NASA Astrophysics Data System (ADS)

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

    2005-03-01

    Sulfur mustard [bis-2-chloroethyl sulfide] is a vesicating agent first used as a weapon of war in WWI. It causes debilitating blisters at the epidermal-dermal junction and involves molecules that are also disrupted by junctional epidermolysis bullosa (JEB) and other blistering skin diseases. Despite its recurring use in global conflicts, there is still no completely effective treatment. We have shown by imaging human keratinocytes in cell culture and in intact epidermal tissues that the basal cells of skin contain well-organized molecules (keratins K5/K14, α6β4 integrin, laminin 5 and α3β1 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.

  10. The polarization effect of a laser in multiphoton Compton scattering

    NASA Astrophysics Data System (ADS)

    Liang, Guo-Hua; Lü, Qing-Zheng; Teng, Ai-Ping; Li, Ying-Jun

    2014-05-01

    The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics (QED) method, which is a non-perturbative theory for the interaction between a plane electromagnetic field and a charged particle. In order to analyze in the real experimental condition, a Lorentz transformation for the cross section of this process is derived between the laboratory frame and the initial rest frame of electrons. The energy of the scattered photon is analyzed, as well as the cross sections for different laser intensities and polarizations and different electron velocities. The angular distribution of the emitted photon is investigated in a special velocity of the electron, in which for a fixed number of absorbed photons, the electron energy will not change after the scattering in the lab frame. We obtain the conclusion that higher laser intensities suppress few-laser-photon absorption and enhance more-laser-photon absorption. A comparison between different polarizations is also made, and we find that the linearly polarized laser is more suitable to generate nonlinear Compton scattering.

  11. In vivo multiphoton microscopy of deep brain tissue.

    PubMed

    Levene, Michael J; Dombeck, Daniel A; Kasischke, Karl A; Molloy, Raymond P; Webb, Watt W

    2004-04-01

    Although fluorescence microscopy has proven to be one of the most powerful tools in biology, its application to the intact animal has been limited to imaging several hundred micrometers below the surface. The rest of the animal has eluded investigation at the microscopic level without excising tissue or performing extensive surgery. However, the ability to image with subcellular resolution in the intact animal enables a contextual setting that may be critical for understanding proper function. Clinical applications such as disease diagnosis and optical biopsy may benefit from minimally invasive in vivo approaches. Gradient index (GRIN) lenses with needle-like dimensions can transfer high-quality images many centimeters from the object plane. Here, we show that multiphoton microscopy through GRIN lenses enables minimally invasive, subcellular resolution several millimeters in the anesthetized, intact animal, and we present in vivo images of cortical layer V and hippocampus in the anesthetized Thy1-YFP line H mouse. Microangiographies from deep capillaries and blood vessels containing fluorescein-dextran and quantum dot-labeled serum in wild-type mouse brain are also demonstrated. PMID:14668300

  12. Security of quantum key distribution with multiphoton components

    PubMed Central

    Yin, Hua-Lei; Fu, Yao; Mao, Yingqiu; Chen, Zeng-Bing

    2016-01-01

    Most qubit-based quantum key distribution (QKD) protocols extract the secure key merely from single-photon component of the attenuated lasers. However, with the Scarani-Acin-Ribordy-Gisin 2004 (SARG04) QKD protocol, the unconditionally secure key can be extracted from the two-photon component by modifying the classical post-processing procedure in the BB84 protocol. Employing the merits of SARG04 QKD protocol and six-state preparation, one can extract secure key from the components of single photon up to four photons. In this paper, we provide the exact relations between the secure key rate and the bit error rate in a six-state SARG04 protocol with single-photon, two-photon, three-photon, and four-photon sources. By restricting the mutual information between the phase error and bit error, we obtain a higher secure bit error rate threshold of the multiphoton components than previous works. Besides, we compare the performances of the six-state SARG04 with other prepare-and-measure QKD protocols using decoy states. PMID:27383014

  13. Spectroscopic analysis of skin intrinsic signals for multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Pena, Ana-Maria; Strupler, Mathias; Boulesteix, Thierry; Senni, Karim; Godeau, Gaston; Beaurepaire, Emmanuel; Schanne-Klein, Marie-Claire

    2006-02-01

    We recorded multiphoton images of human skin biopsies using endogenous sources of nonlinear optical signals. We detected simultaneously two-photon excited fluorescence (2PEF) from intrinsic fluorophores and second harmonic generation (SHG) from collagen. We observed SHG from fibrillar collagens in the dermis, whereas no SHG was detectable from the non fibrillar type IV collagen in the basal laminae. We compared these distinct behaviours of collagens I and IV in SHG microscopy to polarization-resolved surface SHG experiments on thin films of collagens I and IV molecules. We observed similar signals for both types of molecular films, except for the chiroptical contributions which are present only for collagen I and enhance the signal typically by a factor of 2. We concluded that SHG microscopy is a sensitive probe of the micrometer-scale structural organization of collagen in biological tissues. In order to elucidate the origin of the endogenous fluorescence signals, we recorded 2PEF spectra at various positions in the skin biopsies, and compared these data to in vitro spectroscopic analysis. In particular, we studied the keratin fluorescence and determined its 2PEF action cross section. We observed a good agreement between 2PEF spectra recorded in the keratinized upper layers of the epidermis and in a solution of purified keratin. Finally, to illustrate the capabilities of this technique, we recorded 2PEF/SHG images of skin biopsies obtained from patients of various ages.

  14. Tunneling dynamics in multiphoton ionization and attoclock calibration.

    PubMed

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

    2015-02-27

    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. PMID:25768761

  15. Multiphoton population transfer between rovibrational states of HF

    NASA Astrophysics Data System (ADS)

    Topcu, Turker; Robicheaux, Francis

    2011-05-01

    Efficient population transfer by adiabatically chirping through a multiphoton resonance in microwave driven and impulsively kicked Rydberg atoms has been reported both experimentally and theoretically. Previous work has demonstrated that the physical mechanism responsible for the transition can be viewed as a classical process in phase space as well as a quantum mechanical resonant transition. Here we report on our classical and quantum mechanical simulations in which we have exploited this mechanism to vibrationally excite an HF molecule up to | ν = 4 , J > from its ground state using an intense IR pulse. We compare one-dimensional quantum and classical models where there are no rotational degrees of freedom. We find that for low laser intensities, the transition is classically forbidden although it occurs quantum mechanically through tunneling. We show that for larger peak intensities, the transfer can be looked upon as a classical transition in phase space, similar to that observed in the atomic case. We extend our simulations to fully three-dimensional quantum calculations and investigate the effect of coupling between different rotational pathways. We briefly discuss the effect of thermal averaging over the final J-states. This work was supported by the Office of Basic Energy Sciences, U.S. Department of Energy.

  16. Performance evaluation of a sensorless adaptive optics multiphoton microscope.

    PubMed

    Skorsetz, Martin; Artal, Pablo; Bueno, Juan M

    2016-03-01

    A wavefront sensorless adaptive optics technique was combined with a custom-made multiphoton microscope to correct for specimen-induced aberrations. A liquid-crystal-on-silicon (LCoS) modulator was used to systematically generate Zernike modes during image recording. The performance of the instrument was evaluated in samples providing different nonlinear signals and the benefit of correcting higher order aberrations was always noticeable (in both contrast and resolution). The optimum aberration pattern was stable in time for the samples here involved. For a particular depth location within the sample, the wavefront to be precompensated was independent on the size of the imaged area (up to ∼ 360 × 360 μm(2)). The mode combination optimizing the recorded image depended on the Zernike correction control sequence; however, the final images hardly differed. At deeper locations, a noticeable dominance of spherical aberration was found. The influence of other aberration terms was also compared to the effect of the spherical aberration. PMID:26469361

  17. Security of quantum key distribution with multiphoton components

    NASA Astrophysics Data System (ADS)

    Yin, Hua-Lei; Fu, Yao; Mao, Yingqiu; Chen, Zeng-Bing

    2016-07-01

    Most qubit-based quantum key distribution (QKD) protocols extract the secure key merely from single-photon component of the attenuated lasers. However, with the Scarani-Acin-Ribordy-Gisin 2004 (SARG04) QKD protocol, the unconditionally secure key can be extracted from the two-photon component by modifying the classical post-processing procedure in the BB84 protocol. Employing the merits of SARG04 QKD protocol and six-state preparation, one can extract secure key from the components of single photon up to four photons. In this paper, we provide the exact relations between the secure key rate and the bit error rate in a six-state SARG04 protocol with single-photon, two-photon, three-photon, and four-photon sources. By restricting the mutual information between the phase error and bit error, we obtain a higher secure bit error rate threshold of the multiphoton components than previous works. Besides, we compare the performances of the six-state SARG04 with other prepare-and-measure QKD protocols using decoy states.

  18. Security of quantum key distribution with multiphoton components.

    PubMed

    Yin, Hua-Lei; Fu, Yao; Mao, Yingqiu; Chen, Zeng-Bing

    2016-01-01

    Most qubit-based quantum key distribution (QKD) protocols extract the secure key merely from single-photon component of the attenuated lasers. However, with the Scarani-Acin-Ribordy-Gisin 2004 (SARG04) QKD protocol, the unconditionally secure key can be extracted from the two-photon component by modifying the classical post-processing procedure in the BB84 protocol. Employing the merits of SARG04 QKD protocol and six-state preparation, one can extract secure key from the components of single photon up to four photons. In this paper, we provide the exact relations between the secure key rate and the bit error rate in a six-state SARG04 protocol with single-photon, two-photon, three-photon, and four-photon sources. By restricting the mutual information between the phase error and bit error, we obtain a higher secure bit error rate threshold of the multiphoton components than previous works. Besides, we compare the performances of the six-state SARG04 with other prepare-and-measure QKD protocols using decoy states. PMID:27383014

  19. The analysis of aging skin based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  20. Recent developments in the theory of dissociation

    PubMed Central

    SPITZER, CARSTEN; BARNOW, SVEN; FREYBERGER, HARALD J; GRABE, HANS JOERGEN

    2006-01-01

    Although the construct of dissociation was introduced into psychiatry at the end of the 19th century by Pierre Janet, the term still lacks a coherent conceptualization, which is partially reflected by differences in the classification of dissociative and conversion disorders in ICD-10 and DSM-IV. Given the clinical significance of dissociative psychopathology in numerous clinical conditions, it is very valuable that various efforts have been made to refine and to specify current conceptualizations in recent years. The most promising and convincing approaches converge in subdividing dissociation into qualitatively different types, i.e. pathological versus non-pathological dissociation, and "detachment" versus "compartmentalization". We review these concepts and discuss their scientific and clinical potential as well as their limitations. PMID:16946940

  1. The Shutdown Dissociation Scale (Shut-D)

    PubMed Central

    Schalinski, Inga; Schauer, Maggie; Elbert, Thomas

    2015-01-01

    The evolutionary model of the defense cascade by Schauer and Elbert (2010) provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D) was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity). A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups) from healthy controls. The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding. PMID:25976478

  2. Dissociation and Memory Fragmentation in Posttraumatic Stress Disorder: An Evaluation of the Dissociative Encoding Hypothesis

    PubMed Central

    Bedard-Gilligan, Michele; Zoellner, Lori A.

    2012-01-01

    Several prominent theories of posttraumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review, we summarize the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus, initial evidence points more toward a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation. PMID:22348400

  3. Low noise laser system generating 26-fs pulse duration, 30-kW peak power, and tunability from 800- to 1200-nm for ultrafast spectroscopy and multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Resan, Bojan; Brunner, Felix; Rohrbacher, Andreas; Ammann, Hubert; Weingarten, Kurt J.

    2012-01-01

    We demonstrate a novel low noise, tunable, high-peak-power, ultrafast laser system based on a SESAM-modelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression. The spectral selection, tuning, and pulse compression are performed with a simple prism compressor. The spectral broadening and fiber parameters are chosen to insure low-noise operation of the tunable output. The long-term stable output pulses are tunable from 800 to 1200 nm, with a peak power up to 30 kW and pulse duration down to 26 fs. This system is attractive for variety of applications including ultrafast spectroscopy, multiphoton (TPE, SHG, THG, CARS) and multimodal microscopy, nanosurgery, nanostructuring, and optical coherence tomography (OCT). Such system is simpler, lower-cost, and much easier to use (fully turn-key) compared to a currently available solutions for near-infrared ultrashort pulses, typically a Ti:sapphire laser-pumped OPO.

  4. Label-free multiphoton imaging and photoablation of preinvasive cancer cells

    NASA Astrophysics Data System (ADS)

    Zhuo, Shuangmu; Chen, Jianxin; Wu, Guizhu; Zhu, Xiaoqin; Jiang, Xingshan; Xie, Shusen

    2012-01-01

    Detection and treatment of early lesions in epithelial tissue offer several possibilities for curing cancer, but it is challenging. Here, we present an optical technique, the combination of multiphoton imaging and absorption, to label-freely detect and ablate preinvasive cancer cells in epithelial tissue. We find that multiphoton imaging can label-freely visualize the principal features of nuclear atypia associated with epithelial precancerous lesions, and the spatial localization of multiphoton absorption can perform targeted ablation of preinvasive cancer cells with micrometer-sized volume precision. These results indicate that this optical technique has the capability to label-freely visualize and remove preinvasive cancer cells in epithelial tissue. This study highlights the potential of this technique as a "seek-and-treat" tool for early lesions in epithelial tissue.

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

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; König, K.

    2015-02-01

    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.

  6. Distinguishing human normal or cancerous esophagus tissue ex vivo using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liu, N. R.; Chen, G. N.; Wu, S. S.; Chen, R.

    2014-02-01

    Application of multiphoton microscopy (MPM) to clinical cancer research has greatly developed over the last few years. In this paper, we mainly focus on two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) for investigating esophageal cancer. We chiefly discuss the SHG/TPEF image and spectral characteristics of normal and cancerous esophagus submucosa with the combined multi-channel imaging mode and Lambda mode of a multiphoton microscope (LSM 510 META). Great differences can be detected, such as collagen content and morphology, glandular-shaped cancer cells, TPEF/SHG intensity ratio, and so on, which demonstrate that the multiphoton imaging technique has the potential ability for minimally-invasive early cancer diagnosis.

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

    PubMed

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

    2007-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  9. From state dissociation to status dissociatus.

    PubMed

    Antelmi, Elena; Ferri, Raffaele; Iranzo, Alex; Arnulf, Isabelle; Dauvilliers, Yves; Bhatia, Kailash P; Liguori, Rocco; Schenck, Carlos H; Plazzi, Giuseppe

    2016-08-01

    The states of being are conventionally defined by the simultaneous occurrence of behavioral, neurophysiological and autonomic descriptors. State dissociation disorders are due to the intrusion of features typical of a different state into an ongoing state. Disorders related to these conditions are classified according to the ongoing main state and comprise: 1) Dissociation from prevailing wakefulness as seen in hypnagogic or hypnopompic hallucinations, automatic behaviors, sleep drunkenness, cataplexy and sleep paralysis 2) Dissociation from rapid eye movement (REM) sleep as seen in REM sleep behavior disorder and lucid dreaming and 3) Dissociation from NREM sleep as seen in the disorders of arousal. The extreme expression of states dissociation is characterized by the asynchronous occurrence of the various components of the different states that prevents the recognition of any state of being. This condition has been named status dissociatus. According to the underlying disorders/diseases and to their severity, among status dissociatus we may recognize disorders in which such an extreme dissociation occurs only at night time or intermittently (i.e., autoimmune encephalopathies, narcolepsy type 1 and IgLON5 parasomnia), and others in which it occurs nearly continuously with complete loss of any conventionally defined state of being, and of the circadian pattern (agrypnia excitata). Here, we render a comprehensive review of all diseases/disorders associated with state dissociation and status dissociatus and propose a critical classification of this complex scenario. PMID:26431902

  10. Real-time optical diagnosis of gastric cancer with serosal invasion using multiphoton imaging

    PubMed Central

    Yan, Jun; Zheng, Yu; Zheng, Xiaoling; Liu, Zhangyuanzhu; Liu, Wenju; Chen, Dexin; Dong, Xiaoyu; Li, Kai; Liu, Xiumin; Chen, Gang; Lu, Jianping; Chen, Jianxin; Zhuo, Shuangmu; Li, Guoxin

    2016-01-01

    A real-time optical biopsy, which could determine tissue histopathology, would be of extraordinary benefit to staging laparoscopy for gastric cancer with serosal invasion (T4) that requires downstage treatment. We investigated the feasibility of using multiphoton imaging to perform a real-time optical diagnosis of gastric cancer with or without serosal invasion. First, a pilot study was performed to establish the optical diagnostic features of gastric cancer with or without serosal invasion using multiphoton imaging compared with hematoxylin-eosin staining and Masson’s trichrome staining. Second, a blinded study was performed to compare the diagnostic sensitivity, specificity, and accuracy of multiphoton imaging and endoscopic ultrasonography (EUS) for T4 gastric cancer. In the pilot study, multiphoton imaging revealed collagen loss and degradation and cellular and nuclear pleomorphism in gastric cancer with serosal invasion. The collagen content in gastric cancer with or without serosal invasion was 0.36 ± 0.18 and 0.79 ± 0.16 (p < 0.001), respectively. In the blinded study, the sensitivity, specificity, and accuracy of EUS and multiphoton imaging for T4 gastric cancer were 70% and 90% (p = 0.029), 66.67% and 96.67% (p = 0.003), and 68.33% and 93.33% (p = 0.001), respectively. It is feasible to use multiphoton imaging to make a real-time optical diagnosis of gastric cancer with or without serosal invasion. PMID:27499365

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

    PubMed

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

    2011-05-01

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

  12. Mixed-Color Multiphoton Transitions as Additional Quantum Channels for Electron Photoemission

    NASA Astrophysics Data System (ADS)

    Huang, Wayne; Becker, Maria; Beck, Joshua; Batelaan, Herman

    2016-05-01

    We demonstrate mixed-color electron photoemission from tungsten nanotips. In the experiment, second-harmonic photons were introduced to modify the multiphoton emission process. A twofold increase in quantum efficiency results from the opening up of an additional three-photon quantum channel. The super-additive photoelectron signal can be controlled by input power, field polarization, and pulse overlap. The results of our study provide new prospects for quantum photonics, multiphoton microscopy, and spin-polarized electron sources. We acknowledge supports from NSF, Grant Number 1306565, 1430519. NSF Grant Number 1306565, 1430519.

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

    SciTech Connect

    Noh, Heung-Ryoul; Moon, Han Seb

    2011-11-15

    We present a diagrammatic method for complete characterization of multiphoton processes in three-level atomic systems. By considering the interaction routes of the coupling and probe photons for a ladder-type, three-level, noncycling (or cycling) atomic system, we are able to completely discriminate between the pure one-photon and the pure two-photon resonance effects, and the effect of their combination in electromagnetically induced transparency (EIT) using our diagrammatic method. We show that the proposed diagrammatic method is very useful for the analysis of multiphoton processes in ladder-type EIT.

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    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.

  15. Fermi-coupled spherically adapted effective states in the collisionless multiphoton excitation of SF 6

    NASA Astrophysics Data System (ADS)

    Di Lauro, C.; Lattanzi, F.

    1982-10-01

    A calculation method for the collisionless multiphoton excitation of SF 6 by intense CO 2 laser light up to a chain of parallel nv3, ( n - 1) v3 + v2 + v6 … vibrational-rotational ladders linked by Fermi interaction is described. Spherically adapted effective states suitable to the purpose are defined, and matrix elements for multiphoton excitation in the rotatingwave approximation effective hamiltonian formalism are given in this basis. The method is aimed at the investigation of population transfer between the cited parallel vibrational ladders, and is suitable for computer-calculation programmation.

  16. Effect of Multiphoton Processes on Geometric Quantum Computation in Superconducting Circuit QED

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Yong

    2012-11-01

    We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail.

  17. Theory of dissociative tunneling ionization

    NASA Astrophysics Data System (ADS)

    Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

    2016-05-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees of freedom. In the regime where the BO approximation is applicable, imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally, the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fields, where the BO approximation does not apply, the weak-field asymptotic theory describes the spectrum accurately.

  18. Dissociative Ionization of Pyridine by Electron Impact

    NASA Technical Reports Server (NTRS)

    Dateo, Christopher; Huo, Winifred; Kwak, Dochan (Technical Monitor)

    2002-01-01

    In order to understand the damage of biomolecules by electrons, a process important in radiation damage, we undertake a study of the dissociative ionization (DI) of pyridine (C5H5N) from the low-lying ionization channels. The methodology used is the same as in the benzene study. While no experimental DI data are available, we compare the dissociation products from our calculations with the dissociative photoionization measurements of Tixier et al. using dipole (e, e(+) ion) coincidence spectroscopy. Comparisons with the DI of benzene is also made so as to understand the difference in DI between a heterocyclic and an aromatic molecule.

  19. Dissociation of Natural and Artificial Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Misyura, S. Y.

    2016-02-01

    Present work deals with natural and artificial methane hydrate dissociation. The heating of the powder produced due to the temperature difference between the external air and the powder. The dissociation rate was determined by gravimetric method. The range of the partial self-preservation for the natural hydrate is significantly longer than for the artificial one and moved to higher temperatures. The destruction of the natural sample is slower than the artificial one. The time-averaged dissociation rate for the artificial sample is equal to 1,25 %/s and for the natural hydrate corresponds to 0,59 %/s.

  20. Products of Dissociative Recombination in the Ionosphere

    NASA Technical Reports Server (NTRS)

    Cosby, Philip

    1996-01-01

    SRI International undertook a novel experimental measurement of the product states formed by dissociative ro-combination (DR) of C2(+), NO(+), and N2(+) as a function of both electron energy and reactant ion vibrational level. For these measurements we used a recently developed experimental technique for measuring dissociation product distributions that allows both the branching ratios to be accurately determined and the electronic and ro-vibrational state composition of the reactant ions to be specified. DR is the dominant electron loss mechanism in all regions of the ionosphere. In this process, electron attachment to the molecular ion produces an unstable neutral molecule that rapidly dissociates.

  1. Wavepacket theory of collisional dissociation in molecules

    SciTech Connect

    Kulander, K.

    1980-01-01

    An explicit integration scheme is used to solve the time dependent Schroedinger equation for wavepackets which model collisions in the collinear H + H/sub 2/ system. A realistic LEPS-type potential energy surface is used. Collision energies considered are above the dissociation threshold and probabilities for collision induced dissociation are reported. Also quantum mechanical state-to-state transition probabilities are generated. These results are compared to extensive classical trajectory calculations performed on this same system. The time evolution of the wavepacket densities is studied to understand the dynamics of the collinear collisional dissociation process.

  2. Multiphoton ionization-fragmentation patterns of tertiary amines

    NASA Astrophysics Data System (ADS)

    Parker, D. H.; Bernstein, R. B.; Lichtin, D. A.

    1981-09-01

    Multiphoton ionization (MPI)-fragmentation patterns are reported for a series of normal and caged tertiary amines. Ionization is enhanced by two-photon resonance with the 3s and 3p Rydberg states of trimethylamine, triethylamine, and the caged amines quinuclidine and triethylenediamine. Over the wavelength region λ = 400-530 nm, N(CH3)3 ionizes to the parent ion (P) and fragments only by the loss of a H atom to yield the P-H daughter ion; N(C2H5)3 ionizes to its parent ion and fragments by the loss of a methyl to form the P-CH3 ion. The branching ratio of daughter to parent ions is found to be essentially independent of laser intensity but strongly dependent on laser wavelength. The caged amines quinuclidine [N(C2H4)3CH, or ABCO] and triethylenediamine [N(C2H4)3N, or DABCO] fragment extensively over this λ range in a manner dependent on both laser wavelength and intensity. The extent of daughter ion formation in N(CH3)3 and N(C2H5)3 can be understood by consideration of the wavelength regions in which the total available energy from the initial three- or four-photon ionization event exceeds the appearance potential of the given daughter ion. For the caged amines direct observation of this mechanism is masked by fragmentation due to sequential absorption of photons (during the ˜5 ns pulse duration) by the parent and/or daughter ions. The present results show that even for molecules with broad, unstructured UV absorption and MPI spectra such as N(CH3)3 and N(C2H5)3, considerable information on photon-molecule and photon-ion interactions can still be gained by the MPI mass spectrometry technique.

  3. Multiphoton-scattering theory and generalized master equations

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Chang, Darrick E.; Cirac, J. Ignacio

    2015-11-01

    We develop a scattering theory to investigate the multiphoton transmission in a one-dimensional waveguide in the presence of quantum emitters. It is based on a path integral formalism, uses displacement transformations, and does not require the Markov approximation. We obtain the full time evolution of the global system, including the emitters and the photonic field. Our theory allows us to compute the transition amplitude between arbitrary initial and final states, as well as the S matrix of the asymptotic in and out states. For the case of few incident photons in the waveguide, we also rederive a generalized master equation in the Markov limit. We compare the predictions of the developed scattering theory and that with the Markov approximation. We illustrate our methods with five examples of few-photon scattering: (i) by a two-level emitter, (ii) in the Jaynes-Cummings model; (iii) by an array of two-level emitters; (iv) by a two-level emitter in the half-end waveguide; and (v) by an array of atoms coupled to Rydberg levels. In the first two, we show the application of the scattering theory in the photon scattering by a single emitter, and examine the correctness of our theory with the well-known results. In the third example, we analyze the condition of the Markov approximation for the photon scattering in the array of emitters. In the fourth one, we show how a quantum emitter can generate entanglement of outgoing photons. Finally, we highlight the interplay between the phenomenon of electromagnetic-induced transparency and the Rydberg interaction, and show how this results in a rich variety of possibilities in the quantum statistics of the scattering photons.

  4. Large field of view multiphoton microscopy of human skin

    NASA Astrophysics Data System (ADS)

    Balu, Mihaela; Mikami, Hideharu; Hou, Jue; Potma, Eric O.; Tromberg, Bruce J.

    2016-03-01

    Clinical examination crucially relies on the ability to quickly examine large tissue areas and rapidly zoom in to regions of interest. Skin lesions often show irregularity in color and appearance in general, especially when they start to progress towards malignancy. Large field of view (FOV) and automatic translation of the imaging area are critical in the assessment of the entire lesion. Imaging of limited FOVs of the lesion can easily result in false negative diagnosis. We present a multiphoton microscope based on two-photon excited fluorescence and second-harmonic generation that images FOVs of about 0.8 mm2 (without stitching adjacent FOVs) at speeds of 10 frames/second (800 x 800 pixels) with lateral and axial resolutions of 0.5 μm and 2.5 μm, respectively. The main novelty of this instrument is the design of the scan head, which includes a fast galvanometric scanner, relay optics, a beam expander and a high NA objective lens. We optimized the system based on the Olympus 25x, 1.05NA water immersion lens, that features a long working distance of 1 mm. Proper tailoring of the beam expander, which consists of the scan and tube lens elements, enables scaling of the FOV. The design criteria include a flat wavefront of the beam, minimum field curvature, and suppressed spherical aberrations. All aberrations in focus are below the Marechal criterion of 0.07λ rms for diffraction-limited performance. We demonstrate the practical utility of this microscope by ex-vivo imaging of wide FOVs in normal human skin.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  6. Dissociative identity disorder presenting as dermatitis artefacta.

    PubMed

    Ozmen, Mine; Erdogan, Ayten; Aydemir, Ertugrul H; Oguz, Oya

    2006-06-01

    Dermatitis artefacta is a rare psychiatric condition characterized by rubbing of skin blisters and denial of self-infliction. Dissociation may be comorbid with self-injurious behavior. A background of emotional disturbances during formative years and in later life often results in feelings of isolation and insecurity, which can lead to dissociation as a primary defense mechanism used to overcome traumatic events. In this case report, we describe a female patient with dermatitis artefacta associated with dissociative identity disorder. The patient was a 14-year-old girl. Multiple large, deep ulcerations with unnatural shapes were seen on her left forearm. The ulcerations were thought to be self-inflicted. Psychiatric examination revealed that she had a different identity, and inflicted the lesions when this was assumed. This case leads us to suggest that patients with dermatitis artefacta might have comorbid dissociative experiences, which cannot be identified easily. PMID:16796649

  7. Collision-induced gas phase dissociation rates

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1990-01-01

    The Landau-Zener theory of reactive cross sections was applied to diatomic molecules dissociating from a ladder of vibrational states. The result predicts a dissociation rate that is quite well duplicated by an Arrhenius function having a preexponential temperature dependence of about T(sub -1/2), at least for inert collision partners. This relation fits experimental data reasonably well. The theory is then used to calculate the effect of vibrational nonequilibrium on dissociation rate. For Morse oscillators, the results are about the same as given by Hammerling, Kivel, and Teare in their analytic approximation for harmonic oscillators, though at very high temperature a correction for the partition function limit is included. The empirical correction for vibration nonequilibrium proposed by Park, which is a convenient algorithm for CFD calculations, is modified to prevent a drastic underestimation of dissociation rates that occurs with this method when vibrational temperature is much smaller than the kinetic temperature of the gas.

  8. Research Reports: Hallucinogens and Dissociative Drugs

    MedlinePlus

    ... in bizarre or dangerous behavior. Hallucinogens such as LSD, psilocybin, peyote, DMT, and ayahuasca cause emotions to ... Take Hallucinogenic or Dissociative Drugs? How Do Hallucinogens (LSD, Psilocybin, Peyote, DMT, and Ayahuasca) Affect the Brain ...

  9. Dissociation energy of molecules in dense gases

    NASA Technical Reports Server (NTRS)

    Kunc, J. A.

    1992-01-01

    A general approach is presented for calculating the reduction of the dissociation energy of diatomic molecules immersed in a dense (n = less than 10 exp 22/cu cm) gas of molecules and atoms. The dissociation energy of a molecule in a dense gas differs from that of the molecule in vacuum because the intermolecular forces change the intramolecular dynamics of the molecule, and, consequently, the energy of the molecular bond.

  10. Dissociative Ionization of Benzene by Electron Impact

    NASA Technical Reports Server (NTRS)

    Huo, Winifred; Dateo, Christopher; Kwak, Dochan (Technical Monitor)

    2002-01-01

    We report a theoretical study of the dissociative ionization (DI) of benzene from the low-lying ionization channels. Our approach makes use of the fact that electron motion is much faster than nuclear motion and DI is treated as a two-step process. The first step is electron-impact ionization resulting in an ion with the same nuclear geometry as the neutral molecule. In the second step the nuclei relax from the initial geometry and undergo unimolecular dissociation. For the ionization process we use the improved binary-encounter dipole (iBED) model. For the unimolecular dissociation step, we study the steepest descent reaction path to the minimum of the ion potential energy surface. The path is used to analyze the probability of unimolecular dissociation and to determine the product distributions. Our analysis of the dissociation products and the thresholds of the productions are compared with the result dissociative photoionization measurements of Feng et al. The partial oscillator strengths from Feng et al. are then used in the iBED cross section calculations.

  11. Collision induced dissociation of alpha hydroxy acids

    NASA Astrophysics Data System (ADS)

    Bandu, Mary L.; Grubbs, Thomas; Kater, Marcus; Desaire, Heather

    2006-03-01

    Alpha hydroxy acids typically dissociate in tandem mass spectrometric experiments to produce product ions representing a neutral loss of 46 Da (CH2O2) in negative ion mode. Although it is widely accepted that the carboxylate group is lost in the dissociation process, the origin of the remaining two hydrogens is unclear. The current study utilizes an alpha hydroxy acid chemical library and deuterium labeling experiments to identify the origin of the two hydrogens lost during dissociation. Secondly, this study investigates the lower m/z region of the CID spectrum, a region previously unexplored, to aid in characterizing the dissociation mechanism. Further experiments testing the energy requirements and time parameters of the dissociation also are consistent with criteria previously defined for ion-neutral complex formation. In addition to describing the mechanism for the loss of CH2O2, we have conducted experiments that demonstrate the important chemical features of molecules that can prevent alpha hydroxy acids from undergoing the loss of 46 Da. By understanding the chemical composition of the 46 Da loss, the dissociation mechanism responsible for the loss, and the factors that hinder this mechanistic pathway, chemical information about alpha hydroxy acids can be obtained from their CID data.

  12. Unimolecular dissociation of cyclopentadiene and indene

    SciTech Connect

    Yi, W.; Chattopadhyay, A.; Bersohn, R. )

    1991-05-01

    The dissociation of hydrogen atoms from the methylene group of cyclopentadiene (CP) and indene (ID) excited with a 193 nm photon has been studied by hydrogen atom laser induced fluorescence. The rate of dissociation of IND was 7.4{times}10{sup 6} s{sup {minus}1} but that of CP was too fast to measure. The ratio of H atoms to D atoms generated from 5-deuteriocyclopentadiene (5-dCP) was 3.91{plus minus}0.46. Rice--Ramsberger--Kassel--Marcus theory was used to calculate the rates of dissociation of CP and 5-dCP. The quantum yield for dissociating H atoms from CP was 0.85{plus minus}0.07. The ejected H atoms have a Maxwell velocity distribution with temperatures which are equal to the vibrational temperatures, 3690 and 2479 K for CP and IND, respectively. The most important result of the work is this confirmation of an earlier finding on a different set of molecules that the translational temperature of the fragments {ital after} the dissociation is equal to the vibrational temperature {ital before} the dissociation. This is explained by the assumption that the motion of the fast, light hydrogen atom is partly decoupled from that of the heavier, slower atoms.

  13. Why Infrared?

    ERIC Educational Resources Information Center

    Harris, J. R.

    1973-01-01

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

  14. Semiclassical analysis of long-wavelength multiphoton processes: The Rydberg atom

    NASA Astrophysics Data System (ADS)

    Vela-Arevalo, Luz V.; Fox, Ronald F.

    2004-06-01

    We study the problem of multiphoton processes for intense, long-wavelength irradiation of atomic and molecular electrons. An exact, nonperturbative approach is applied to the standard vector potential coupling Hamiltonian for a three-dimensional hydrogenlike atom in a microwave field treated semiclassically. Multiphoton probability exchange is calculated in both the velocity and the length gauges, by applying the Goeppert-Mayer gauge transformation. The expansion of the time-dependent solution in terms of Floquet states delineates the mechanism of multiphoton transitions. A detailed analysis of the Floquet states and quasienergies as functions of the field parameters allows us to describe the relation between avoided quasienergy crossings and multiphoton probability exchange. We formulate analytical expressions for the variation of quasienergies and Floquet states with respect to the field parameters, and demonstrate that avoided quasienergy crossings are accompanied by dramatic changes in the Floquet states. Analysis of the Floquet states, for small values of the field strength, yields selection rules for the avoided quasienergy crossings. In the case of strong fields, the simultaneous choice of frequency and strength of the field producing an avoided crossing results in improved ionization probability.

  15. Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2008-07-15

    Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

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

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell'Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

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

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [

    F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)
    ], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  18. The Multiphoton Interaction of Lambda Model Atom and Two-Mode Fields

    NASA Technical Reports Server (NTRS)

    Liu, Tang-Kun

    1996-01-01

    The system of two-mode fields interacting with atom by means of multiphotons is addressed, and the non-classical statistic quality of two-mode fields with interaction is discussed. Through mathematical calculation, some new rules of non-classical effects of two-mode fields which evolue with time, are established.

  19. Multi-photon transitions and Rabi resonance in continuous wave EPR.

    PubMed

    Saiko, Alexander P; Fedaruk, Ryhor; Markevich, Siarhei A

    2015-10-01

    The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines. PMID:26295168

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  1. Photoelectron momentum spectra for multiphoton ionization of Hydrogen atoms by intense laser pulses

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Serge; Macek, Joseph

    2007-06-01

    Full three-dimensional electron momentum distribution for multiphoton ionization of Hydrogen atoms by intense laser pulses are calculated by solving the time-dependent solutions of Schr"odinger equation on a three-dimensional lattice in a scaled coordinate representation (CSLTDSE). This approach allows one to circumvent many difficulties related to the propagation of wave function to macroscopic distances.

  2. Nonergodicity in Electron Capture Dissociation Investigated Using Hydrated Ion Nanocalorimetry

    PubMed Central

    Leib, Ryan D.; Donald, William A.; Bush, Matthew F.; O’Brien, Jeremy T.; Williams, Evan R.

    2007-01-01

    Hydrated divalent magnesium and calcium clusters are used as nanocalorimeters to measure the internal energy deposited into size-selected clusters upon capture of a thermally generated electron. The infrared radiation emitted from the cell and vacuum chamber surfaces as well as from the heated cathode results in some activation of these clusters, but this activation is minimal. No measurable excitation due to inelastic collisions occurs with the low-energy electrons used under these conditions. Two different dissociation pathways are observed for the divalent clusters that capture an electron: loss of water molecules (pathway I) and loss of a H atom and water molecules (pathway II). For Ca(H2O)n2+, pathway I occurs exclusively for n ≥ 30 whereas pathway II occurs exclusively for n ≤ 22 with a sharp transition in the branching ratio for these two processes that occurs for n ≈ 24. The number of water molecules lost by both pathways increases with increasing cluster size reaching a broad maximum between n = 23 and 32, and then decreases for larger clusters. From the number of water molecules that are lost from the reduced cluster, the average and maximum possible internal energy is determined to be ~4.4 and 5.2 eV, respectively, for Ca(H2O)302+. This value is approximately the same as the calculated ionization energies of M(H2O)n+, M = Mg and Ca, for large n indicating that the vast majority of the recombination energy is partitioned into internal modes of the ion and that the dissociation of these ions is statistical. For smaller clusters, estimates of the dissociation energies for the loss of H and of water molecules are obtained from theory. For Mg(H2O)n2+, n = 4 – 6, the average internal energy deposition is estimated to be 4.2 – 4.6 eV. The maximum possible energy deposited into the n = 5 cluster is < 7.1 eV, which is significantly less than the calculated recombination energy for this cluster. There does not appear to be a significant trend in the

  3. Supersonic jet/multiphoton ionization spectrometry of chemical species resulting from thermal decomposition and laser ablation of polymers

    NASA Astrophysics Data System (ADS)

    Hozumi, Masami; Murata, Yoshiaki; Cheng-Huang Lin, Imasaka, Totaro

    1995-04-01

    The chemical species resulting from thermal decomposition and laser ablation of polymers are measured by excitation/fluorescence and multiphoton ionization/mass spectrometries after supersonic jet expansion for rotational cooling to simply the optical spectrum. The signal of minor chemical species occurred is strongly enhanced by resonant excitation and multiphoton ionization, and even the isomer can be clearly differentiated. For example, p-cresol occurred by thermal decomposition of polycarbonate is detected selectively by mass-selected resonant multiphoton ionization spectrometry. Various chemical species occurred by laser ablation of even a polystyrene foam are also measured by this technique.

  4. Ex vivo applications of multiphoton microscopy in urology

    NASA Astrophysics Data System (ADS)

    Jain, Manu; Mukherjee, Sushmita

    2016-03-01

    Background: Routine urological surgery frequently requires rapid on-site histopathological tissue evaluation either during biopsy or intra-operative procedure. However, resected tissue needs to undergo processing, which is not only time consuming but may also create artifacts hindering real-time tissue assessment. Likewise, pathologist often relies on several ancillary methods, in addition to H&E to arrive at a definitive diagnosis. Although, helpful these techniques are tedious and time consuming and often show overlapping results. Therefore, there is a need for an imaging tool that can rapidly assess tissue in real-time at cellular level. Multiphoton microscopy (MPM) is one such technique that can generate histology-quality images from fresh and fixed tissue solely based on their intrinsic autofluorescence emission, without the need for tissue processing or staining. Design: Fresh tissue sections (neoplastic and non-neoplastic) from biopsy and surgical specimens of bladder and kidney were obtained. Unstained deparaffinized slides from biopsy of medical kidney disease and oncocytic renal neoplasms were also obtained. MPM images were acquired using with an Olympus FluoView FV1000MPE system. After imaging, fresh tissues were submitted for routine histopathology. Results: Based on the architectural and cellular details of the tissue, MPM could characterize normal components of bladder and kidney. Neoplastic tissue could be differentiated from non-neoplastic tissue and could be further classified as per histopathological convention. Some of the tumors had unique MPM signatures not otherwise seen on H&E sections. Various subtypes of glomerular lesions were identified as well as renal oncocytic neoplasms were differentiated on unstained deparaffinized slides. Conclusions: We envision MPM to become an integral part of regular diagnostic workflow for rapid assessment of tissue. MPM can be used to evaluate the adequacy of biopsies and triage tissues for ancillary studies

  5. Thermal dissociation behavior and dissociation enthalpies of methane-carbon dioxide mixed hydrates.

    PubMed

    Kwon, Tae-Hyuk; Kneafsey, Timothy J; Rees, Emily V L

    2011-06-30

    Replacement of methane with carbon dioxide in hydrate has been proposed as a strategy for geologic sequestration of carbon dioxide (CO(2)) and/or production of methane (CH(4)) from natural hydrate deposits. This replacement strategy requires a better understanding of the thermodynamic characteristics of binary mixtures of CH(4) and CO(2) hydrate (CH(4)-CO(2) mixed hydrates), as well as thermophysical property changes during gas exchange. This study explores the thermal dissociation behavior and dissociation enthalpies of CH(4)-CO(2) mixed hydrates. We prepared CH(4)-CO(2) mixed hydrate samples from two different, well-defined gas mixtures. During thermal dissociation of a CH(4)-CO(2) mixed hydrate sample, gas samples from the head space were periodically collected and analyzed using gas chromatography. The changes in CH(4)-CO(2) compositions in both the vapor phase and hydrate phase during dissociation were estimated based on the gas chromatography measurements. It was found that the CO(2) concentration in the vapor phase became richer during dissociation because the initial hydrate composition contained relatively more CO(2) than the vapor phase. The composition change in the vapor phase during hydrate dissociation affected the dissociation pressure and temperature; the richer CO(2) in the vapor phase led to a lower dissociation pressure. Furthermore, the increase in CO(2) concentration in the vapor phase enriched the hydrate in CO(2). The dissociation enthalpy of the CH(4)-CO(2) mixed hydrate was computed by fitting the Clausius-Clapeyron equation to the pressure-temperature (PT) trace of a dissociation test. It was observed that the dissociation enthalpy of the CH(4)-CO(2) mixed hydrate lays between the limiting values of pure CH(4) hydrate and CO(2) hydrate, increasing with the CO(2) fraction in the hydrate phase. PMID:21604671

  6. Dissociations between developmental dyslexias and attention deficits

    PubMed Central

    Lukov, Limor; Friedmann, Naama; Shalev, Lilach; Khentov-Kraus, Lilach; Shalev, Nir; Lorber, Rakefet; Guggenheim, Revital

    2014-01-01

    We examine whether attention deficits underlie developmental dyslexia, or certain types of dyslexia, by presenting double dissociations between the two. We took into account the existence of distinct types of dyslexia and of attention deficits, and focused on dyslexias that may be thought to have an attentional basis: letter position dyslexia (LPD), in which letters migrate within words, attentional dyslexia (AD), in which letters migrate between words, neglect dyslexia, in which letters on one side of the word are omitted or substituted, and surface dyslexia, in which words are read via the sublexical route. We tested 110 children and adults with developmental dyslexia and/or attention deficits, using extensive batteries of reading and attention. For each participant, the existence of dyslexia and the dyslexia type were tested using reading tests that included stimuli sensitive to the various dyslexia types. Attention deficit and its type was established through attention tasks assessing sustained, selective, orienting, and executive attention functioning. Using this procedure, we identified 55 participants who showed a double dissociation between reading and attention: 28 had dyslexia with normal attention and 27 had attention deficits with normal reading. Importantly, each dyslexia with suspected attentional basis dissociated from attention: we found 21 individuals with LPD, 13 AD, 2 neglect dyslexia, and 12 surface dyslexia without attention deficits. Other dyslexia types (vowel dyslexia, phonological dyslexia, visual dyslexia) also dissociated from attention deficits. Examination of 55 additional individuals with both a specific dyslexia and a certain attention deficit found no attention function that was consistently linked with any dyslexia type. Specifically, LPD and AD dissociated from selective attention, neglect dyslexia dissociated from orienting, and surface dyslexia dissociated from sustained and executive attention. These results indicate that

  7. Competitive bond rupture in the photodissociation of bromoacetyl chloride and 2- and 3-bromopropionyl chloride: adiabatic versus diabatic dissociation.

    PubMed

    Hsu, Ming-Yi; Tsai, Po-Yu; Wei, Zheng-Rong; Chao, Meng-Hsuan; Zhang, Bing; Kasai, Toshio; Lin, King-Chuen

    2013-04-01

    Competitive bond dissociation mechanisms for bromoacetyl chloride and 2- and 3-bromopropionyl chloride following the (1) [n(O)→π*(C=O)] transition at 234-235 nm are investigated. Branching ratios for C−Br/C−Cl bond fission are found by using the (2+1) resonance-enhanced multiphoton ionization (REMPI) technique coupled with velocity ion imaging. The fragment branching ratios depend mainly on the dissociation pathways and the distances between the orbitals of Br and the C=O chromophore. C−Cl bond fission is anticipated to follow an adiabatic potential surface for a strong diabatic coupling between the n(O)π*(C=O) and np (Cl)σ*(C−Cl) bands. In contrast, C−Br bond fission is subject to much weaker coupling between n(O)π*(C=O) and np (Br)σ*(C−Br). Thus, a diabatic pathway is preferred for bromoacetyl chloride and 2-bromopropionyl chloride, which leads to excited-state products. For 3-bromopropionyl chloride, the available energy is not high enough to reach the excited-state products such that C−Br bond fission must proceed through an adiabatic pathway with severe suppression by nonadiabatic coupling. The fragment translational energies and anisotropy parameters for the three molecules are also analyzed and appropriately interpreted. PMID:23400968

  8. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E.; Miller, Michael A.

    2010-08-24

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  9. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E.; Miller, Michael A.

    2007-03-13

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  10. Refractive index change in dissociating shocked benzene

    SciTech Connect

    Erskine, D.J.

    1994-06-01

    A calculation is made of the refractive index of a shocked solution of hydrocarbon species and spheroidal carbon particles that would be the dissociation products of benzene. The results is evaluated for benzene shocked to 15 GPa, both for an arbitrary endpoint distribution of products and reactant, and for a specific endpoint distribution suggested by a statistical-mechanical calculation. In the case of diamond particles, the refractive index is predicted to decrease by a small amount (from 1.96 to 1.75) as the dissociation proceeds. In the case of graphite particles of large oblateness, the refractive index could increase significantly through the dissociation (from 1.96 to 2.75 for infinitely oblate platelets). Thus the measurement of the time dependent refractive index through the dissociation of shocked benzene can indicate the morphology of the carbon particulates as well as the time scale for this reaction. We propose using the refractive index as a measure of completion of the dissociation reaction. This would allow a determination of the instantaneous amount of carbon in particulate form, information which is valuable in conjunction with Mie scattering experiments for example.

  11. Intrinsic disorder accelerates dissociation rather than association.

    PubMed

    Umezawa, Koji; Ohnuki, Jun; Higo, Junichi; Takano, Mitsunori

    2016-08-01

    The intrinsically disordered protein (IDP) has distinct properties both physically and biologically: it often becomes folded when binding to the target and is frequently involved in signal transduction. The physical property seems to be compatible with the biological property where fast association and dissociation between IDP and the target are required. While fast association has been well studied, fueled by the fly-casting mechanism, the dissociation kinetics has received less attention. We here study how the intrinsic disorder affects the dissociation kinetics, as well as the association kinetics, paying attention to the interaction strength at the binding site (i.e., the quality of the "fly lure"). Coarse-grained molecular dynamics simulation of the pKID-KIX system, a well-studied IDP system, shows that the association rate becomes larger as the disorder-inducing flexibility that was imparted to the model is increased, but the acceleration is marginal and turns into deceleration as the quality of the fly lure is worsened. In contrast, the dissociation rate is greatly enhanced as the disorder is increased, indicating that intrinsic disorder serves for rapid signal switching more effectively through dissociation than association. Proteins 2016; 84:1124-1133. © 2016 Wiley Periodicals, Inc. PMID:27122223

  12. Ion-induced dissociation dynamics of acetylene

    SciTech Connect

    De, Sankar; Rajput, Jyoti; Roy, A.; Safvan, C. P.; Ghosh, P. N.

    2008-02-15

    We report on the results of dissociation dynamics of multiple charged acetylene molecules formed in collision with 1.2 MeV Ar{sup 8+} projectiles. Using the coincidence map, we can separate out the different dissociation pathways between carbon and hydrogen ionic fragments as well as complete two-body breakup events. From the measured slopes of the coincidence islands for carbon atomic fragments and theoretical values determined from the charge and momentum distribution of the correlated particles, we observe a diatom like behavior of the C-C charged complex during dissociation of multiply charged C{sub 2}H{sub 2}. We conclude that this behavior in breakup dynamics is a signature of sequentiality in dissociation of this multiply charged molecular species. The shape and orientation of the islands give further information about the momentum balance in the fragmentation process of two- or many-body dissociation pathways. Kinetic energy release of different breakup channels are reported here and compared with values calculated from the pure Coulomb explosion model.

  13. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, Charles G. [Pleasanton, CA

    1978-08-29

    A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

  14. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, C.G.

    1978-08-29

    Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

  15. Mechanisms and energetics of hydride dissociation reactions on surfaces of plasma-deposited silicon thin films

    NASA Astrophysics Data System (ADS)

    Singh, Tejinder; Valipa, Mayur S.; Mountziaris, T. J.; Maroudas, Dimitrios

    2007-11-01

    We report results from a detailed analysis of the fundamental silicon hydride dissociation processes on silicon surfaces and discuss their implications for the surface chemical composition of plasma-deposited hydrogenated amorphous silicon (a-Si:H) thin films. The analysis is based on a synergistic combination of first-principles density functional theory (DFT) calculations of hydride dissociation on the hydrogen-terminated Si(001)-(2×1) surface and molecular-dynamics (MD) simulations of adsorbed SiH3 radical precursor dissociation on surfaces of MD-grown a-Si :H films. Our DFT calculations reveal that, in the presence of fivefold coordinated surface Si atoms, surface trihydride species dissociate sequentially to form surface dihydrides and surface monohydrides via thermally activated pathways with reaction barriers of 0.40-0.55eV. The presence of dangling bonds (DBs) results in lowering the activation barrier for hydride dissociation to 0.15-0.20eV, but such DB-mediated reactions are infrequent. Our MD simulations on a-Si :H film growth surfaces indicate that surface hydride dissociation reactions are predominantly mediated by fivefold coordinated surface Si atoms, with resulting activation barriers of 0.35-0.50eV. The results are consistent with experimental measurements of a-Si :H film surface composition using in situ attenuated total reflection Fourier transform infrared spectroscopy, which indicate that the a-Si :H surface is predominantly covered with the higher hydrides at low temperatures, while the surface monohydride, SiH(s ), becomes increasingly more dominant as the temperature is increased.

  16. Infrared Camera

    NASA Technical Reports Server (NTRS)

    1997-01-01

    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.

  17. Dissociation in virtual reality: depersonalization and derealization

    NASA Astrophysics Data System (ADS)

    Garvey, Gregory P.

    2010-01-01

    This paper looks at virtual worlds such as Second Life7 (SL) as possible incubators of dissociation disorders as classified by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition3 (also known as the DSM-IV). Depersonalization is where "a person feels that he or she has changed in some way or is somehow unreal." Derealization when "the same beliefs are held about one's surroundings." Dissociative Identity Disorder (DID), previously known as multiple personality disorder fits users of Second Life who adopt "in-world" avatars and in effect, enact multiple distinct identities or personalities (known as alter egos or alters). Select questions from the Structured Clinical Interview for Depersonalization (SCI-DER)8 will be discussed as they might apply to the user's experience in Second Life. Finally I would like to consider the hypothesis that rather than a pathological disorder, dissociation is a normal response to the "artificial reality" of Second Life.

  18. Electron Transfer Dissociation of Oligonucleotide Cations.

    PubMed

    Smith, Suncerae I; Brodbelt, Jennifer S

    2009-06-01

    Electron transfer dissociation (ETD) of multi-protonated 6 - 20-mer oligonucleotides and 12- and 14-mer duplexes is compared to collision activated dissociation (CAD). ETD causes efficient charge reduction of the multi-protonated oligonucleotides in addition to limited backbone cleavages to yield sequence ions of low abundance. Subsequent CAD of the charge-reduced oligonucleotides formed upon electron transfer, in a net process termed electron transfer collision activated dissociation (ETcaD), results in rich fragmentation in terms of w, a, z, and d products, with a marked decrease in the abundance of base loss ions and internal fragments. Complete sequencing was possible for nearly all oligonucleotides studied. ETcaD of an oligonucleotide duplex resulted in specific backbone cleavages, with conservation of weaker non-covalent bonds. PMID:20161288

  19. Infrared Thermometer

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Diatek Corporation, San Diego, CA and the Jet Propulsion Lab developed the Diatek Model 7000 aural thermometer which weighs only eight ounces, and measures temperature in less than two seconds using infrared astronomy technology to measure the amount of infrared energy emitted by the eardrum (the same way temperature of stars and planets is measured). This method avoids contact with mucous membranes, virtually eliminating the possibility of cross infection, and permits temperature measurement of newborn, critically ill, or incapacitated patients. Diatek Corporation was purchased by Welch Allyn Inc. The Diatek Model 7000 is now marketed as SureTemp.

  20. Infrared Scanning

    NASA Technical Reports Server (NTRS)

    1987-01-01

    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.

  1. Infrared astronomy

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  2. Psychotherapy and pharmacotherapy for patients with dissociative identity disorder.

    PubMed

    Gentile, Julie P; Dillon, Kristy S; Gillig, Paulette Marie

    2013-02-01

    There is a wide variety of what have been called "dissociative disorders," including dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, and forms of dissociative disorder not otherwise specified. Some of these diagnoses, particularly dissociative identity disorder, are controversial and have been questioned by many clinicians over the years. The disorders may be under-diagnosed or misdiagnosed, but many persons who have experienced trauma report "dissociative" symptoms. Prevalence of dissociative disorders is unknown, but current estimates are higher than previously thought. This paper reviews clinical, phenomenological, and epidemiological data regarding diagnosis in general, and illustrates possible treatment interventions for dissociative identity disorder, with a focus on psychotherapy interventions and a review of current psychopharmacology recommendations as part of a comprehensive multidisciplinary treatment plan. PMID:23556139

  3. Swirling flow of a dissociated gas

    NASA Technical Reports Server (NTRS)

    Wolfram, W. R., Jr.; Walker, W. F.

    1975-01-01

    Most physical applications of the swirling flow, defined as a vortex superimposed on an axial flow in the nozzle, involve high temperatures and the possibility of real gas effects. The generalized one-dimensional swirling flow in a converging-diverging nozzle is analyzed for equilibrium and frozen dissociation using the ideal dissociating gas model. Numerical results are provided to illustrate the major effects and to compare with results obtained for a perfect gas with constant ratio of specific heats. It is found that, even in the case of real gases, perfect gas calculations can give a good estimate of the reduction in mass flow due to swirl.

  4. Dissociation of ultracold molecules with Feshbach resonances

    SciTech Connect

    Duerr, Stephan; Volz, Thomas; Rempe, Gerhard

    2004-09-01

    Ultracold molecules are associated from an atomic Bose-Einstein condensate by ramping a magnetic field across a Feshbach resonance. The reverse ramp dissociates the molecules. The kinetic energy released in the dissociation process is used to measure the widths of four Feshbach resonances in {sup 87}Rb. This method to determine the width works remarkably well for narrow resonances even in the presence of significant magnetic-field noise. In addition, a quasimonoenergetic atomic wave is created by jumping the magnetic field across the Feshbach resonance.

  5. Dissociation and recombination in an inhomogeneous gas

    NASA Astrophysics Data System (ADS)

    Kuščer, Ivan

    1991-09-01

    The system of Boltzmann equations of Ludwig and Heil for a dissociating gas mixture is reviewed and reformulated in terms of differential cross sections. For the purpose of Monte Carlo simulations, collision models of the type of Borgnakke and Larsen are proposed. In case of short-lived transient flows of molecular gases and at not too high temperatures, simulation of scattering collisions is expected to suffice; the distribution function of the dissociated particles can be evaluated afterwards by integration, and recombination can be ignored.

  6. Quantum Zeno control of coherent dissociation

    SciTech Connect

    Khripkov, C.; Vardi, A.

    2011-08-15

    We study the effect of dephasing on the coherent dissociation dynamics of an atom-molecule Bose-Einstein condensate. We show that when phase-noise intensity is strong with respect to the inverse correlation time of the stimulated process, dissociation is suppressed via a Bose enhanced quantum Zeno effect. This is complementary to the quantum Zeno control of phase-diffusion in a bimodal condensate by symmetric noise [Phys. Rev. Lett. 100, 220403 (2008)] in that the controlled process here is phase formation and the required decoherence mechanism for its suppression is purely phase noise.

  7. Water Dissociation upon Adsorption onto Free Iron Clusters Is Size Dependent.

    PubMed

    Kiawi, Denis M; Chernyy, Valeriy; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L B F M; Bakker, Joost M

    2016-07-01

    Cationic iron clusters, produced through laser ablation and subsequently complexed with a water molecule Fen(+)-H2O (n = 6-15) are mass-selectively investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 300-1700 cm(-1) spectral range. The experimental data are complemented by density functional theory calculations at the OPBE/TZP level for the Fe13(+)-H2O system. The observed spectra can be explained by a mixture of clusters where for a majority water is adsorbed molecularly but for a small but significant fraction also dissociation of water molecules occurs. The bands observed at frequencies 300-700 cm(-1) exhibit regular, size-dependent frequency shifts, showing that (a) dissociation takes places on all cluster sizes and (b) the interaction of water with the cluster surface is not influenced much by the particular cluster structure. The intensity evolution of the absorption bands suggests that dissociation is increasingly probable for larger cluster sizes. PMID:27266896

  8. Infrared telescope

    NASA Technical Reports Server (NTRS)

    Karr, G. R.; Hendricks, J. B.

    1985-01-01

    The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

  9. Infrared Thermometers

    ERIC Educational Resources Information Center

    Schaefers, John

    2006-01-01

    An infrared (IR) thermometer lab offers the opportunity to give science students a chance to measure surface temperatures, utilizing off-the-shelf technology. Potential areas of study include astronomy (exoplanets), electromagnetic spectrum, chemistry, evaporation rates, anatomy, crystal formation, and water or liquids. This article presents one…

  10. Infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Lopez, B. A.

    1984-11-01

    Infrared spectroscopic analysis is reviewed. Applications to chemical analysis of preimpregnated carbon fiber materials, including polystyrene spectra, epoxy resin analysis, mineral loads analysis, determination of epoxy groups and identification of spurious organic materials are discussed. The advantages of the method for quality control are pointed out.

  11. Carbon monoxide dissociative attachment and resonant dissociation by electron-impact

    NASA Astrophysics Data System (ADS)

    Laporta, V.; Tennyson, J.; Celiberto, R.

    2016-02-01

    Low-energy dissociative electron attachment and resonant electron impact dissociation of CO molecule are considered. Ro-vibrationally resolved cross sections and rate coefficients for both the processes are calculated using an ab-initio model based on the low-lying \\text{X}{{}2}\\Pi resonance of CO-. Final results show that the cross sections increases very rapidly as a function of the ro-vibrational level; these cross sections should be useful for understanding kinetic dissociation of CO in strongly non-equilibrium plasmas.

  12. Kinetic ion thermometers for electron transfer dissociation.

    PubMed

    Pepin, Robert; Tureček, František

    2015-02-19

    Peptide fragment ions of the z-type were used as kinetic ion thermometers to gauge the internal energy of peptide cation-radicals produced by electron transfer in the gas-phase. Electron transfer dissociation (ETD)-produced z2 ions containing the leucine residue, z2(Leu-Lys) and z2(Leu-Arg), were found to undergo spontaneous dissociation by loss of C3H7 that was monitored by time-resolved kinetic measurements on the time scale of the linear ion trap mass spectrometer. Kinetic modeling of the dissociations, including collisional cooling and product loss by neutralization, provided unimolecular rate constants for dissociation that were converted to the z ion internal energies using RRKM theory. The internal energy of z2(Leu-Lys) and z2(Leu-Arg) fragment ions was found to decrease with the increasing size of the precursor peptide ion, indicating vibrational energy partitioning between the ion and neutral fragments and ergodic behavior. The experimentally determined excitation in the peptide cation-radicals upon electron transfer (285-327 kJ mol(-1)) was found to be lower than that theoretically calculated from the reaction exothermicity. The reasons for this missing energy are discussed. PMID:25594857

  13. Double Dissociation between Reading and Spelling Deficits

    ERIC Educational Resources Information Center

    Moll, Kristina; Landerl, Karin

    2009-01-01

    In two studies dissociations between reading and spelling skills were examined. Study 1 reports equally high prevalence rates for isolated deficits in reading (7%) or spelling (6%) in a representative sample (N = 2,029) of German-speaking elementary school children. In Study 2, children with isolated deficits were presented with the same words to…

  14. EVIDENCE FOR CO DISSOCIATION ON RHODIUM SURFACES

    SciTech Connect

    Castner, D.G.; Dubois, L.H.; Sexton, B.A.; Somorjai, G.A.

    1980-06-01

    Carbon monoxide adsorbs molecularly on rhodium surfaces at 300K, but if the rhodium samples are heated in the presence of carbon monoxide, there is evidence for carbon-oxygen bond breaking at step and/or defect sites. The effects of step and defect site density, subsurface oxygen concentration, and oxygen dissolution into the rhodium lattice on CO dissociation are discussed.

  15. Enabling Multiphoton and Second Harmonic Generation Imaging in Paraffin-Embedded and Histologically Stained Sections

    PubMed Central

    Monaghan, Michael G.; Kroll, Sebastian; Brucker, Sara Y.

    2016-01-01

    Nonlinear microscopy, namely multiphoton imaging and second harmonic generation (SHG), is an established noninvasive technique useful for the imaging of extracellular matrix (ECM). Typically, measurements are performed in vivo on freshly excised tissues or biopsies. In this article, we describe the effect of rehydrating paraffin-embedded sections on multiphoton and SHG emission signals and the acquisition of nonlinear images from hematoxylin and eosin (H&E)-stained sections before and after a destaining protocol. Our results reveal that bringing tissue sections to a physiological state yields a significant improvement in nonlinear signals, particularly in SHG. Additionally, the destaining of sections previously processed with H&E staining significantly improves their SHG emission signals during imaging, thereby allowing sufficient analysis of collagen in these sections. These results are important for researchers and pathologists to obtain additional information from paraffin-embedded tissues and archived samples to perform retrospective analysis of the ECM or gain additional information from rare samples. PMID:27018844

  16. High-fidelity spatially resolved multiphoton counting for quantum imaging applications.

    PubMed

    Chrapkiewicz, Radosław; Wasilewski, Wojciech; Banaszek, Konrad

    2014-09-01

    We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for nonlinearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of the Mandel parameter and the noise reduction factor in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one detected photon per an event area-substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution. PMID:25166081

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

    SciTech Connect

    Fox, Ronald F.; Vela-Arevalo, Luz V.

    2002-11-01

    The problem of multiphoton processes for intense, long-wavelength irradiation of atomic and molecular electrons is presented. The recently developed method of quasiadiabatic time evolution is used to obtain a nonperturbative analysis. When applied to the standard vector potential coupling, an exact auxiliary equation is obtained that is in the electric dipole coupling form. This is achieved through application of the Goeppert-Mayer gauge. While the analysis to this point is general and aimed at microwave irradiation of Rydberg atoms, a Floquet analysis of the auxiliary equation is presented for the special case of the periodically driven harmonic oscillator. Closed form expressions for a complete set of Floquet states are obtained. These are used to demonstrate that for the oscillator case there are no multiphoton resonances.

  18. In vitro imaging of embryonic stem cells using multiphoton luminescence of gold nanoparticles

    PubMed Central

    Nagesha, D; Laevsky, GS; Lampton, P; Banyal, R; Warner, C; DiMarzio, C; Sridhar, S

    2007-01-01

    Recent advances in nonlinear optical techniques and materials such as quantum wells, nanowires and noble-metal nanoparticles have led to advances in cellular imaging wherein various nanoparticles have been shown to improve both in vitro and in vivo visualization. In this paper, we demonstrate in vitro imaging using multi-photon photoluminescence of gold nanoparticles from two different cell types – Dictyostelium discoideum and mouse embryonic stem cells. By observing nanoparticles we show that embryonic stem cells maintained their ability to proliferate for several passages while grown in the presence of gold nanoparticles. The advantages of multi-photon luminescence using gold nanoparticles have important implications for use in stem cell proliferation experiments and in vitro experiments to monitor differentiation. PMID:18203448

  19. Statistical properties of multiphoton time-dependent three-boson coupled oscillators

    SciTech Connect

    Abdalla, M. Sebawe; Perina, Jan; Krepelka, Jaromir

    2006-06-15

    We investigate the quantum statistics of three time-dependent coupled oscillators in the presence of multiphoton processes. The system is connected with the two-atom multiphoton Tavis-Cummings model. The solution of the Heisenberg equations of the motion is obtained in a compact form. We assume that the modes are initially prepared in coherent states, and we discuss nonclassical phenomena (squeezing and sub-Poissonian behavior). Further, we examine the joint quasi-distribution functions as well as photon-number distribution and its factorial moments. The system has shown that the nonclassical effect is apparent in compound modes (1,3) and (2,3). Moreover, the superstructure phenomenon is observed when the photon transition is increased.

  20. Multiphoton ac Stark effect in a bichromatically driven two-level atom

    NASA Astrophysics Data System (ADS)

    Rudolph, T. G.; Freedhoff, H. S.; Ficek, Z.

    1998-08-01

    We study the interaction of a two-level atom with two lasers of different frequencies and amplitudes: a strong laser of Rabi frequency 2Ω1 on resonance with the atomic transition, and a weaker laser detuned by subharmonics (2Ω1/n) of the Rabi frequency of the first. We find that under these conditions the second laser couples the dressed states created by the first in an n-photon process, resulting in ``doubly dressed'' states and in a ``multiphoton ac Stark'' effect. We calculate the eigenstates of the doubly dressed atom and their energies, and illustrate the role of this multiphoton ac Stark effect in its fluorescence, absorption, and Autler-Townes spectra.

  1. Identification of normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections

    NASA Astrophysics Data System (ADS)

    Zhou, Yi; Chen, Zhifen; Kang, Deyong; li, Lianhuang; Zhuo, Shuangmu; Zhu, Xiaoqin; Guan, Guoxian; Chen, Jianxin

    2016-01-01

    Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) as a potential diagnostic tool is attractive. MPM can effectively provide information about morphological and biochemical changes in biological tissues at the molecular level. In this paper, we attempt to identify normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections (both in transverse and longitudinal sections). The results show that MPM can display different microstructure changes in the transverse and longitudinal sections of colorectal muscularis propria. MPM also can quantitatively describe the alteration of collagen content between normal and cancerous muscle layers. These are important pathological findings that MPM images can bring more detailed complementary information about tissue architecture and cell morphology through observing the transverse and longitudinal sections of colorectal muscularis propria. This work demonstrates that MPM can be better for identifying the microstructural characteristics of normal and cancerous human colorectal muscularis propria in different sections.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The early diagnosis of intestinal metaplasia (IM) in the stomach together with effective therapeutic interventions is crucial to reducing the mortality-rates of the patients associated with gastric cancer. However, it is challenging during conventional white-light endoscopy, and histological analysis remains the ‘gold standard’ for the final diagnosis. Here, we describe a label-free imaging method, multiphoton microscopy (MPM), for the identification of IM in the stomach. It was found that multiphoton imaging provides cellular and subcellular details to the identification of IM from normal gastric tissues. In particular, there is significant difference in the population density of goblet cells between normal and IM gastric tissues, providing substantial potential to become a quantitative intrinsic marker for in vivo clinical diagnosis of early gastric lesions. To our knowledge, this is the first demonstration of the potential of MPM for the identification of IM.

  3. Multiphoton microscopy with clearing for three dimensional histology of kidney biopsies

    PubMed Central

    Olson, Eben; Levene, Michael J.; Torres, Richard

    2016-01-01

    We present a multiphoton microscopy approach with clearing optimized for pathology evaluation producing image quality comparable to traditional histology. Use of benzyl alcohol/benzyl benzoate with 4',6-diamidino-2-phenylindole and eosin in an optimized imaging setup results in optical sections nearly indistinguishable from traditionally-cut sections. Application to human renal tissue demonstrates diagnostic-level image quality can be maintained through 1 millimeter of tissue. Three dimensional perspectives reveal changes of glomerular capsule cells not evident on single sections. Collagen-derived second harmonic generation can be visualized through entire biopsies. Multiphoton microscopy with clearing has potential for increasing the yield of histologic evaluation of biopsy specimens. PMID:27570700

  4. High-Resolution Mosaic Imaging with Multifocal, Multiphoton Photon-Counting Microscopy

    SciTech Connect

    Chandler, E.; Hoover, E.; Field, J.; Sheetz, K.; Amir, W.; Carriles, R.; Ding, S. Y.; Squier, J.

    2009-04-10

    High-resolution mosaic imaging is performed for the first time to our knowledge with a multifocal, multiphoton, photon-counting imaging system. We present a novel design consisting of a home-built femtosecond Yb-doped KGdWO{sub 4} laser with an optical multiplexer, which is coupled with a commercial Olympus IX-71 microscope frame. Photon counting is performed using single-element detectors and an inexpensive electronic demultiplexer and counters.

  5. Two-color multiphoton ionization of diazabicyclooctane in a supersonic free jet

    NASA Astrophysics Data System (ADS)

    Fujii, Masaaki; Ebata, Takayuki; Mikami, Naohiko; Ito, Mitsuo

    1983-11-01

    Two-color multiphoton ionization (MPI) spectroscopy has been applied for diazabicyclooctane (DABCO) in a supersonic free jet. The MPI spectra due to transitions from the various vibronic levels of the S 1 (3s Rydberg) state which were excited by the first laser revealed the high Rydberg states above the adiabatic ionization potential. The ionization process and the vibrational potential of the ion are discussed.

  6. Multiphoton Process and Anomalous Potential of Cell Membrane by Laser Radiation

    NASA Technical Reports Server (NTRS)

    Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhar, Ping; Dong, Lifang

    1996-01-01

    In this paper, by the use of quantum biology and quantum optics, the laser induced potential variation of cell membrane has been studied. Theoretically, we have found a method of calculating the monophoton and multiphoton processes in the formation of the anomalous potential of cell membrane. In contrast with the experimental results, our numerical result is in the same order. Therefore, we have found the possibility of cancer caused by the laser induced anomalous cell potential.

  7. Continuum generation in ultra high numerical aperture fiber with application to multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sayler, Nicholas

    Nonlinear microscopy benefits from broadband laser sources, enabling efficient excitation of an array of fluorophores, for example. This work demonstrates broadening of a narrow band input pulse (6 nm to 40 nm) centered at 1040 nm with excellent shot-to-shot stability. In a preliminary demonstration, multiphoton imaging with pulses from the fiber is performed. In particular second harmonic imaging of corn starch is performed.

  8. Multiphoton lasing in atomic potassium: Steady-state and dynamic behavior

    SciTech Connect

    Font, J. L.; Fernandez-Soler, J. J.; Vilaseca, R.; Gauthier, Daniel J.

    2005-12-15

    We show theoretically that it is possible to generate laser light based on two-photon and other high-order multiphoton processes when an atomic beam of optically driven potassium atoms crosses a high-finesse optical cavity. We use a rigorous model that takes into account all the atomic substates involved in the optical interactions and is valid for any drive and lasing field intensities. The polarizations of the drive and lasing fields are assumed to be fixed. Stable and unstable laser emission branches are obtained, which are represented as a function of cavity detuning and are analyzed in terms of the fundamental quantum processes yielding them. Closed-curve laser-emission profiles are obtained for multiphoton lasing based on processes involving more than one lasing photon. Two-photon laser emission branches show relatively long segments of stationary emission, combined in general with some segments of nonstationary emission, or with segments of mixture with three-photon emission processes. Rayleigh and hyper-Rayleigh processes can become simultaneously resonant, entailing in such case a large and fast transfer of population from the atomic initial ground sublevel to other ground sublevels with different z components of the total angular momentum. They could be useful in generating multiphoton correlated field states. In all cases the largest laser emission intensities are obtained from the highest-order processes, rather than the lowest. These results open the way to the understanding of experiments performed in the past years and suggest possibilities for more efficient and varied types of multiphoton laser operation.

  9. Experimental Dissociation of Methane Hydrates Through Depressurization

    NASA Astrophysics Data System (ADS)

    Borgfeldt, T.; Flemings, P. B.; Meyer, D.; You, K.

    2015-12-01

    We dissociated methane hydrates by stepwise depressurization. The initial hydrates were formed by injecting gas into a cylindrical sample of brine-saturated, coarse-grained sand at hydrate-stable conditions with the intention of reaching three-phase equilibrium. The sample was initially at 1°C with a pore pressure of 1775 psi and a salinity of 7 wt. % NaBr. The depressurization setup consisted of one pump filled with tap water attached to the confining fluid port and a second pump attached to the inlet port where the methane was injected. Depressurization was conducted over sixteen hours at a constant temperature of 1°C. The pore pressure was stepwise reduced from 1775 psi to atmospheric pressure by pulling known volumes of gas from the sample. After each extraction, we recorded the instantaneous and equilibrium pore pressure. 0.503 moles of methane were removed from the sample. The pore pressure decreased smoothly and nonlinearly with the cumulative gas withdrawn from the sample. We interpret that hydrate began to dissociate immediately with depressurization, and it continued to dissociate when the pressure decreased below the three-phase pressure for 1°C and 0 wt. % salinity. Two breaks in slope in the pressure vs. mass extracted data are bounded by smooth, nonlinear curves with differing slopes on either side. We attribute the breaks to dissociation of three zones of hydrate concentration. We created a box model to simulate the experimental behavior. For a 10% initial gas saturation (estimated from the hydrate formation experiment and based on mass conservation), an initial hydrate saturation of 55% is required to match the total methane extracted from the sample. Future experiments will be conducted over a longer timespan while monitoring hydrate dissociation with CT imaging throughout the process.

  10. Initial electronic coherence in molecular dissociation induced by an attosecond pulse

    NASA Astrophysics Data System (ADS)

    Medišauskas, Lukas; Patchkovskii, Serguei; Harvey, Alex; Brambila, Danilo S.; Neidel, Christian; Klei, Jesse; Rouzée, Arnaud; Vrakking, Marc J. J.; Ivanov, Misha Yu.

    2015-11-01

    We investigate the influence of the attosecond electron dynamics of photoionization on the femtosecond fragmentation of the molecular ion left behind. We consider the dissociative photoionization dynamics of the N2 molecule, induced by an attosecond extreme-ultraviolet (XUV) pulse in the presence of a moderately strong infrared (IR) laser field. We show that the kinetic energy spectrum of N+ fragments depends on (i) the phases between the different electronic states of N2 + established by the photoionization process and (ii) phases associated with the vibrational dynamics in the dissociating molecular ion. We show that the phase acquired during the photoionization can be obtained from the dependence of the N+ ion kinetic energy release spectra on the time delay between the XUV and IR pulses.

  11. The Effect of Hydrogen on the Bonding and Dissociation of Carbon Monoxide on AN IRON(100) Surface

    NASA Astrophysics Data System (ADS)

    Nassir, Mohamed Husain

    1993-01-01

    Adsorption and coadsorption of CO and H _2 on Fe(100) was studied using the following six methods: Temperature programmed desorption (TPD), x -ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), high resolution electron energy loss spectroscopy (HREELS), single reflection Fourier transform infrared spectroscopy (FTIR) and low-energy electron diffraction (LEED). The binding and dissociation of CO on a clean and hydrogen presaturated Fe(100) surface were investigated to provide better understanding of the first step in the Fischer-Tropsch synthesis, an important industrial catalytic reaction for converting CO and hydrogen to hydrocarbon. CO adsorbs molecularly on the clean surface in three states alpha_1, alpha_2 and alpha_3 . At temperatures above 350 K but below 440 K, CO is bound to the surface only in the highly perturbed alpha_3 state (pi -bonded geometry). The CO alpha_3 molecules are believed to occupy the 4-fold hollow sites. When the surface temperature is raised above 440 K, a fraction of the alpha_3 desorbs and the remainder dissociates. The dissociation fragments replace the CO alpha_3 molecules in the 4-fold hollow sites. These fragments recombine at higher temperatures and appear as beta CO. The bonding and dissociation of CO in the alpha_3 received more attention because it is believed that this state is a precursor to dissociation. A model describing the partitioning between desorption and dissociation is proposed in which the dissociation fragments displace the strongly bound CO in the beta -bonded state. The stoichiometry of this reaction at saturation requires that only half the original CO adsorbed in the beta-bonded CO state can dissociate. Presaturating the surface with hydrogen affects the bonding and dissociation of CO on the iron surface. One effect is to weaken CO-Fe bonds which results in a very weakly bound state (alpha^' _1). In addition to the alpha ^'_1 state, presaturating the surface with hydrogen

  12. Thermal dissociation behavior and dissociation enthalpies of methane-carbon dioxide mixed hydrates

    SciTech Connect

    Kwon, T.H.; Kneafsey, T.J.; Rees, E.V.L.

    2011-02-15

    Replacement of methane with carbon dioxide in hydrate has been proposed as a strategy for geologic sequestration of carbon dioxide (CO{sub 2}) and/or production of methane (CH{sub 4}) from natural hydrate deposits. This replacement strategy requires a better understanding of the thermodynamic characteristics of binary mixtures of CH{sub 4} and CO{sub 2} hydrate (CH{sub 4}-CO{sub 2} mixed hydrates), as well as thermophysical property changes during gas exchange. This study explores the thermal dissociation behavior and dissociation enthalpies of CH{sub 4}-CO{sub 2} mixed hydrates. We prepared CH{sub 4}-CO{sub 2} mixed hydrate samples from two different, well-defined gas mixtures. During thermal dissociation of a CH{sub 4}-CO{sub 2} mixed hydrate sample, gas samples from the head space were periodically collected and analyzed using gas chromatography. The changes in CH{sub 4}-CO{sub 2} compositions in both the vapor phase and hydrate phase during dissociation were estimated based on the gas chromatography measurements. It was found that the CO{sub 2} concentration in the vapor phase became richer during dissociation because the initial hydrate composition contained relatively more CO{sub 2} than the vapor phase. The composition change in the vapor phase during hydrate dissociation affected the dissociation pressure and temperature; the richer CO{sub 2} in the vapor phase led to a lower dissociation pressure. Furthermore, the increase in CO{sub 2} concentration in the vapor phase enriched the hydrate in CO{sub 2}. The dissociation enthalpy of the CH{sub 4}-CO{sub 2} mixed hydrate was computed by fitting the Clausius-Clapeyron equation to the pressure-temperature (PT) trace of a dissociation test. It was observed that the dissociation enthalpy of the CH{sub 4}-CO{sub 2} mixed hydrate lays between the limiting values of pure CH{sub 4} hydrate and CO{sub 2} hydrate, increasing with the CO{sub 2} fraction in the hydrate phase.

  13. Psychotherapy and Pharmacotherapy for Patients with Dissociative Identity Disorder

    PubMed Central

    Gentile, Julie P.; Dillon, Kristy S.

    2013-01-01

    There is a wide variety of what have been called “dissociative disorders,” including dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, and forms of dissociative disorder not otherwise specified. Some of these diagnoses, particularly dissociative identity disorder, are controversial and have been questioned by many clinicians over the years. The disorders may be under-diagnosed or misdiagnosed, but many persons who have experienced trauma report “dissociative” symptoms. Prevalence of dissociative disorders is unknown, but current estimates are higher than previously thought. This paper reviews clinical, phenomenological, and epidemiological data regarding diagnosis in general, and illustrates possible treatment interventions for dissociative identity disorder, with a focus on psychotherapy interventions and a review of current psychopharmacology recommendations as part of a comprehensive multidisciplinary treatment plan. PMID:23556139

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  16. Multiphoton fragmentation and ionization of CF{sub 2}HCl molecules and clusters by UV radiation

    SciTech Connect

    Lokhman, V. N.; Ogurok, D. D.; Ryabov, E. A.

    2006-07-15

    The results of experimental studies of multiphoton ionization of CF{sub 2}HCl molecules and clusters by UV laser radiation in the wavelength range 217-236 nm are reported. In the case of molecules, the main reaction products are CF{sub 2}H{sup +} and CF{sup +} ions as well as atomic chlorine. It is found that the spectra of the products of ionization of free molecules and molecules condensed into clusters differ qualitatively: multiphoton ionization of clusters does not yield CF{sub 2}H{sup +} ions. The dependences of the ion yield on the intensity of laser radiation and its wavelength are measured. The effect of a constant electric field and the radiation spectral width on the multiphoton ionization process is demonstrated. The shape of the velocity distributions is determined for a number of products. A strong anisotropy is detected in the reaction of formation of CF{sub 2}H{sup +} ions. Possible mechanisms for these processes are discussed.

  17. Weak-field multiphoton femtosecond coherent control in the single-cycle regime.

    PubMed

    Chuntonov, Lev; Fleischer, Avner; Amitay, Zohar

    2011-03-28

    Weak-field coherent phase control of atomic non-resonant multiphoton excitation induced by shaped femtosecond pulses is studied theoretically in the single-cycle regime. The carrier-envelope phase (CEP) of the pulse, which in the multi-cycle regime does not play any control role, is shown here to be a new effective control parameter that its effect is highly sensitive to the spectral position of the ultrabroad spectrum. Rationally chosen position of the ultrabroadband spectrum coherently induces several groups of multiphoton transitions from the ground state to the excited state of the system: transitions involving only absorbed photons as well as Raman transitions involving both absorbed and emitted photons. The intra-group interference is controlled by the relative spectral phase of the different frequency components of the pulse, while the inter-group interference is controlled jointly by the CEP and the relative spectral phase. Specifically, non-resonant two- and three-photon excitation is studied in a simple model system within the perturbative frequency-domain framework. The developed intuition is then applied to weak-field multiphoton excitation of atomic cesium (Cs), where the simplified model is verified by non-perturbative numerical solution of the time-dependent Schrödinger equation. We expect this work to serve as a basis for a new line of femtosecond coherent control experiments. PMID:21451714

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

    NASA Astrophysics Data System (ADS)

    Gainer, Christian F.; Romanowski, Marek

    2013-02-01

    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 μm, and an axial resolution of ~5 μm. 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.

  19. Multiphoton fluorescence imaging of NADH to quantify metabolic changes in epileptic tissue in vitro

    NASA Astrophysics Data System (ADS)

    Chia, Thomas H.; Zinter, Joseph; Spencer, Dennis D.; Williamson, Anne; Levene, Michael J.

    2007-02-01

    A powerful advantage of multiphoton microscopy is its ability to image endogenous fluorophores such as the ubiquitous coenzyme NADH in discrete cellular populations. NADH is integral in both oxidative and non-oxidative cellular metabolism. NADH loses fluorescence upon oxidation to NAD +; thus changes in NADH fluorescence can be used to monitor metabolism. Recent studies have suggested that hypo metabolic astrocytes play an important role in cases of temporal lobe epilepsy (TLE). Current theories suggest this may be due to defective and/or a reduced number of mitochondria or dysfunction of the neuronal-astrocytic metabolic coupling. Measuring NADH fluorescence changes following chemical stimulation enables the quantification of the cellular distribution of metabolic anomalies in epileptic brain tissue compared to healthy tissue. We present what we believe to be the first multiphoton microscopy images of NADH from the human brain. We also present images of NADH fluorescence from the hippocampus of the kainate-treated rat TLE model. In some experiments, human and rat astrocytes were selectively labeled with the fluorescent dye sulforhodamine 101 (SR101). Our results demonstrate that multiphoton microscopy is a powerful tool for assaying the metabolic pathologies associated with temporal lobe epilepsy in humans and in rodent models.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  1. Real-time digital signal processing in multiphoton and time-resolved microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The use of multiphoton interactions in biological tissue for imaging contrast requires highly sensitive optical measurements. These often involve signal processing and filtering steps between the photodetector and the data acquisition device, such as photon counting and lock-in amplification. These steps can be implemented as real-time digital signal processing (DSP) elements on field-programmable gate array (FPGA) devices, an approach that affords much greater flexibility than commercial photon counting or lock-in devices. We will present progress toward developing two new FPGA-based DSP devices for multiphoton and time-resolved microscopy applications. The first is a high-speed multiharmonic lock-in amplifier for transient absorption microscopy, which is being developed for real-time analysis of the intensity-dependence of melanin, with applications in vivo and ex vivo (noninvasive histopathology of melanoma and pigmented lesions). The second device is a kHz lock-in amplifier running on a low cost (50-200) development platform. It is our hope that these FPGA-based DSP devices will enable new, high-speed, low-cost applications in multiphoton and time-resolved microscopy.

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

    PubMed

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

    2015-01-01

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

  3. Multiphoton and tunneling ionization probability of atoms and molecules in an intense laser field

    NASA Astrophysics Data System (ADS)

    Zhao, Song-Feng; Liu, Lu; Zhou, Xiao-Xin

    2014-02-01

    We theoretically studied ionization of atoms exposed to an intense laser field by using three different methods, i.e., the numerical solution of the single-active-electron approximation based time-dependent Schrödinger equation (SAE-TDSE), the Perelomov-Popov-Terent'ev (PPT) model, and the Ammosov-Delone-Krainov (ADK) model. The ionization of several linear molecules in a strong laser field is also investigated with the molecular ADK (MO-ADK) and the molecular PPT (MO-PPT) model. We show that the ionization probability from the PPT and the MO-PPT model agrees well with the corresponding SAE-TDSE result in both the multiphoton and tunneling ionization regimes. By considering the volume effect of the laser field, the ionization signal obtained from the PPT and the MO-PPT model fits well the experimental data in the whole range of the multiphoton and tunneling ionization regimes. However, both the ADK and MO-ADK models seriously underestimate the ionization probabilities (or signals) in the multiphoton regime.

  4. Role of quantum trajectory in high-order harmonic generation in the Keldysh multiphoton regime

    NASA Astrophysics Data System (ADS)

    Li, Peng-Cheng; Chu, Shih-I.

    2016-05-01

    We present a systematic study of quantum-trajectory analysis of high-order harmonic generation (HHG) by solving accurately the time-dependent Schrödinger equation for a hydrogen atom in the multiphoton regime where the Keldysh parameter is greater unity. We perform the time-frequency transform to explore the spectral characteristics of the HHG. We find that the time-frequency spectra exhibit a broken distribution at above-threshold HHG due to the competition associated with the short- and long-trajectories when the ionization process is pushed from the multiphoton regime into the tunneling regime, it implies that the harmonic emission in the broken regions of time-frequency spectra are suppressed. In addition, we present a time-dependent density-functional theory approach for an ab initio study of the effect of correlated multielectron responses on the harmonic emission of Ar atom associated with the quantum trajectories in the multiphoton regime. This work is partially supported by DOE.

  5. Multiphoton Imaging of Upconverting Lanthanide Nanoparticles in Three Dimensional Models of Cancer

    PubMed Central

    Gainer, Christian F.; Romanowski, Marek

    2013-01-01

    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 μm, and an axial resolution of ~5 μm. 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. PMID:24353385

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  11. Using multiphoton fluorescence lifetime imaging to characterize liver damage and fluorescein disposition in liver in vivo

    NASA Astrophysics Data System (ADS)

    Thorling, Camilla A.; Studier, Hauke; Crawford, Darrell; Roberts, Michael S.

    2016-03-01

    Liver disease is the fifth most common cause of death and unlike many other major causes of mortality, liver disease rates are increasing rather than decreasing. There is no ideal measurement of liver disease and although biopsies are the gold standard, this only allows for a spot examination and cannot follow dynamic processes of the liver. Intravital imaging has the potential to extract detailed information over a larger sampling area continuously. The aim of this project was to investigate whether multiphoton and fluorescence lifetime imaging microscopy could detect early liver damage and to assess whether it could detect changes in metabolism of fluorescein in normal and diseased livers. Four experimental groups were used in this study: 1) control; 2) ischemia reperfusion injury; 3) steatosis and 4) steatosis with ischemia reperfusion injury. Results showed that multiphoton microscopy could visualize morphological changes such as decreased fluorescence of endogenous fluorophores and the presence of lipid droplets, characteristic of steatosis. Fluorescence lifetime imaging microscopy showed increase in NADPH in steatosis with and without ischemia reperfusion injury and could detect changes in metabolism of fluorescein to fluorescein monoglurcuronide, which was impaired in steatosis with ischemia reperfusion injury. These results concluded that the combination of multiphoton microscopy and fluorescence lifetime imaging is a promising method of assessing early stage liver damage and that it can be used to study changes in drug metabolism in the liver as an indication of liver disease and has the potential to replace the traditional static liver biopsy currently used.

  12. What contributes to predicting change in the treatment of dissociation: initial levels of dissociation, PTSD, or overall distress?

    PubMed

    Brand, Bethany L; Stadnik, Ryan

    2013-01-01

    Individuals with dissociative disorders (DDs) suffer from high levels of dissociation as well as posttraumatic stress disorder (PTSD) and general distress. No research has investigated how changes in dissociation relate to changes in other symptoms over the course of treatment in patients with DD. Using a prospective, naturalistic design, we collected reports of symptoms from a sample of therapists and their patients diagnosed with dissociative identity disorder or dissociative disorder not otherwise specified who participated in the Treatment Outcome of Patients with Dissociative Disorders study. The patients completed surveys at intake (Time 1) into the study and at 30-month follow-up (Time 4). We found that dissociative symptoms, including amnesia, depersonalization/derealization, and absorption, at the initial assessment of the study ("initial") were related to initial levels of PTSD and general distress and that changes in dissociative symptoms were related to changes in PTSD and general distress. Initial dissociation was a significant predictor of change in dissociation at 30 months when we controlled for length of time for follow-up, length of time practicing therapy, and length of time treating dissociative patients. Our results suggest that a reduction in dissociative symptoms in DD patients is associated with reductions in the overall severity of dissociative, posttraumatic stress, and distress symptoms. PMID:23627481

  13. Infrared floodlight

    DOEpatents

    Levin, Robert E.; English, George J.

    1986-08-05

    An infrared floodlight assembly designed particularly for security purposes and including a heat-conducting housing, a lens secured to the housing to provide a closure therefor, and a floodlight located within (and surrounded by) the housing. The floodlight combines the use of a tungsten halogen light source and dichroic hot and cold mirrors for directing substantially only infrared radiation toward the assembly's forward lens. Visible radiation is absorbed by the housing's interior wall(s) and, optionally, by a filter located between the floodlight and lens. An optional means may be used within the floodlight to reflect all forward radiation back toward the paraboloidal hot mirror or, alternatively, to reflect only visible radiation in this direction. The dichroic hot and cold mirrors preferably each comprise a glass substrate having multiple layers of titanium dioxide and silicon dioxide thereon.

  14. CO chemisorption and dissociation at high coverages during CO hydrogenation on Ru catalysts.

    PubMed

    Loveless, Brett T; Buda, Corneliu; Neurock, Matthew; Iglesia, Enrique

    2013-04-24

    Density functional theory (DFT) and infrared spectroscopy results are combined with mechanism-based rate equations to assess the structure and thermodynamics of chemisorbed CO (CO*) and its activation during Fischer-Tropsch synthesis (FTS). CO* binding becomes weaker with increasing coverage on Ru(0001) and Ru201 clusters, but such decreases in binding energy occur at higher coverages on Ru201 clusters than on Ru(0001) surfaces (CO*/Ru = 1.55 to 0.75); such differences appear to reflect weaker repulsive interactions on the curved surfaces prevalent on small Ru201 clusters. Ru201 clusters achieve stable supramonolayer coverages (CO*/Ru > 1) by forming geminal dicarbonyls at low-coordination corner/edge atoms. CO* infrared spectra on Ru/SiO2 (~7 nm diameter) detect mobile adlayers that anneal into denser structures at saturation. Mechanism-based FTS rate equations give activation energies that reflect the CO*-saturated surfaces prevalent during catalysis. DFT-derived barriers show that CO* predominantly reacts at (111) terraces via H-assisted reactions, consistent with measured effects of H2 and CO pressures and cluster size effects on rates and O-rejection selectivities. Barriers are much higher for unassisted CO* dissociation on (111) terraces and low-coordination atoms, including step-edge sites previously proposed as active sites for CO* dissociation during FTS. DFT-derived barriers indicate that unassisted CO* dissociation is irreversible, making such steps inconsistent with measured rates. The modest activation barriers of H-assisted CO* dissociation paths remove a requirement for special low-coordination sites for unassisted CO* activation, which is inconsistent with higher rates on larger clusters. These conclusions seem generally applicable to Co, Fe, and Ru catalysts, which show similar FTS rate equations and cluster size effects. This study also demonstrates the feasibility and relevance of DFT treatments on the curved and crowded cluster surfaces where

  15. Dissociation of acetaldehyde in intense laser field: Coulomb explosion or field-assisted dissociation?

    NASA Astrophysics Data System (ADS)

    Elshakre, Mohamed E.; Gao, Lirong; Tang, Xiaoping; Wang, Sufan; Shu, Yafei; Kong, Fanao

    2003-09-01

    Dissociation of acetaldehyde in moderate strong laser field of 1013-1014W/cm2 was investigated. Singly charged parent ion CH3CHO+ and fragmental ions CH3+, CHO+, C2H4+, O+, CH2CHO+, and H+ were produced by 800 nm laser of 100 fs pulse duration and recorded by time-of-flight mass spectrometer. The CH3+ fragment further dissociated to CH2+, CH+, and C+ ions at higher intensity. Ab initio calculated results show that the singly-, doubly-, and triply charged parent ions are stable. So, the dissociation mechanism was not due to Coulomb explosion of multicharged ion. A field-assisted dissociation (FAD) theory, which assumes that only one bond undergoes dissociation while the rest of the molecular geometry stays unchanged, was employed to treat the dissociation dynamics. Accordingly, the dressed potential energy surfaces of the ground state for the parent and the fragment ions were calculated. Corresponding quasiclassical trajectory calculations show that the bond ruptures take place in the order of C-C, C-O, and C-H, agreeing with the observation. The observed angular dependence and charge distribution of the product ions can also be interpreted by the FAD theory.

  16. Does phasic trauma treatment make patients with dissociative identity disorder treatment more dissociative?

    PubMed

    Brand, Bethany; Loewenstein, Richard J

    2014-01-01

    Proponents of the iatrogenic model of the etiology of dissociative identity disorder (DID) have expressed concern that treatment focused on direct engagement and interaction with dissociated self-states harms DID patients. However, empirical data have shown that this type of DID treatment is beneficial. Analyzing data from the prospective Treatment of Patients With Dissociative Disorders (TOP DD) Study, we test empirically whether DID treatment is associated with clinically adverse manifestations of dissociated self-states: acting so differently that one feels like different people, hearing voices, and dissociative amnesia. We show that, over the course of the study, there were significant decreases in feeling like different people and hearing voices. These results indicate that this form of DID treatment does not lead to symptomatic worsening in these dimensions, as predicted by the iatrogenic model. Indeed, treatment provided by TOP DD therapists reduced, rather than increased, the extent to which patients experienced manifestations of pathological dissociation. Because severe symptomatology and impairment are associated with DID, iatrogenic harm may come from depriving DID patients of treatment that targets DID symptomatology. PMID:24377972

  17. Infrared retina

    DOEpatents

    Krishna, Sanjay; Hayat, Majeed M.; Tyo, J. Scott; Jang, Woo-Yong

    2011-12-06

    Exemplary embodiments provide an infrared (IR) retinal system and method for making and using the IR retinal system. The IR retinal system can include adaptive sensor elements, whose properties including, e.g., spectral response, signal-to-noise ratio, polarization, or amplitude can be tailored at pixel level by changing the applied bias voltage across the detector. "Color" imagery can be obtained from the IR retinal system by using a single focal plane array. The IR sensor elements can be spectrally, spatially and temporally adaptive using quantum-confined transitions in nanoscale quantum dots. The IR sensor elements can be used as building blocks of an infrared retina, similar to cones of human retina, and can be designed to work in the long-wave infrared portion of the electromagnetic spectrum ranging from about 8 .mu.m to about 12 .mu.m as well as the mid-wave portion ranging from about 3 .mu.m to about 5 .mu.m.

  18. Infrared backscattering

    NASA Technical Reports Server (NTRS)

    Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

    1989-01-01

    All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

  19. In-Vacuum Dissociator for Atomic-Hydrogen Masers

    NASA Technical Reports Server (NTRS)

    Vessot, R. F.

    1987-01-01

    Thermal control and vacuum sealing achieved while contamination avoided. Simple, relatively inexpensive molecular-hydrogen dissociator for atomic-hydrogen masers used on Earth or in vacuum of space. No air cooling required, and absence of elastomeric O-ring seals prevents contamination. In-vacuum dissociator for atomic hydrogen masers, hydrogen gas in glass dissociator dissociated by radio-frequency signal transmitted from surrounding 3-turn coil. Heat in glass conducted away by contacting metal surfaces.

  20. Multiphoton tomography with tunable Ti:sapphire laser (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans G.; Li, Tuan; König, Karsten

    2016-03-01

    Femtosecond near infrared laser microscopes are widely used to perform high resolution 3D imaging of biological samples based on second harmonic generation (SHG) and non-resonant simultaneous absorption of two or more photons at GW/cm2 intensities. However, high contrast imaging of living specimens without any destructive effect is limited to certain laser and exposure parameters with respect to the optical properties of the target. We compared three different femtosecond lasers, including a novel ultra-compact ultrashort fiber laser, in the range of 15-180 fs and repetition rates of 50-300 MHz for optimal non-destructive two-photon autofluorescence imaging. In particular we determined the thresholds for the onset of photodamage effects such as impaired cell reproduction.