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Sample records for picosecond infrared studies

  1. Picosecond infrared study of carbonmonoxy cytochrome c oxidase: Ligand transfer dynamics and binding orientations

    SciTech Connect

    Peterson, K.A.; Stoutland, P.O.; Dyer, R.B.; Woodruff, W.H.

    1991-01-01

    Cytochrome c oxidase (CcO), an enzyme which catalyzes the reduction of dioxygen to water in the terminal step of the respiratory chain, combines several fundamental chemical processes in performing its function. The coordination chemistry and ligation dynamics of the cytochrome {alpha}{sub 3}-Cu{sub B} site, where O{sub 2} and other small molecules such as CO, NO and isocyanates can bind, are essential to the function of the enzyme. Recent time-resolved infrared (TRIR) and visible absorption measurements have shown that coordination to Cu{sub B}{sup +} is an obligatory mechanistic step for CO entering the cytochrome {alpha}{sub 3} heme site and departing the protein after photodissociation. The timescale (> 10{sup {minus}7} s) of the TRIR measurements precluded observation of the ligation dynamics immediately following photodissociation. Here we report a picosecond timescale TRIR study of these events. The results reveal that the photoinitiated ligand transfer of CO from Fe{sub a3}{sup 2+} to Cu{sub B}{sup +}, which are believed to lie 4--5 {Angstrom} apart, occurs within 1 ps. 9 refs., 2 figs.

  2. Laser-induced reactions in a deep UV resist system: Studied with picosecond infrared spectroscopy

    SciTech Connect

    Lippert, T.; Koskelo, A.; Stoutland, P.O.

    1995-12-31

    One of the most technologically important uses of organic photochemistry is in the imaging industry where radiation-sensitive organic monomers and polymers are used in photoresists. A widely-used class of compounds for imaging applications are diazoketones; these compounds undergo a photoinduced Wolff rearrangement to form a ketene intermediate which subsequently hydrolyses to a base-soluble, carboxylic acid. Another use of organic molecules in polymer matrices is for dopant induced ablation of polymers. As part of a program to develop diagnostics for laser driven reactions in polymer matrices, we have investigated the photoinduced decomposition of 5-diazo-2,2-dimethyl-1,3-dioxane-4,6-dione (5-diazo Meldrum`s acid, DM) in a PMMA matrix using picosecond infrared spectroscopy. In particular, irradiation of DM with a 60 ps 266 nm laser pulse results in immediate bleaching of the diazo infrared band ({nu} = 2172 cm{sup -1}). Similarly, a new band appears within our instrument response at 2161 cm{sup -1} (FWHM = 29 cm{sup -1}) and is stable to greater than 6 ns.; we assign this band to the ketene photoproduct of the Wolff rearrangement. Using deconvolution techniques we estimate a limit for its rate of formation of {tau} < 20 ps. The linear dependence of the absorbance change with the pump power (266 nm) even above the threshold of ablation suggest that material ejection take place after 6ns.

  3. Picosecond melting of peptide nanotubes using an infrared laser: a nonequilibrium simulation study.

    PubMed

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

    2015-11-01

    Self-assembled functional peptide biomaterials are emerging with a wide range of envisioned applications in the field of nanotechnology. Currently, methods and tools have been developed to control and manipulate as well as to explore new properties of self-assembled structures. However, considerably fewer studies are being devoted to developing efficient methods to degrade or recycle such extremely stable biomaterials. With this in mind, here we suggest a theoretical framework, inspired by the recent developed mid-infrared free-electron laser pulse technology, to dissociate peptide nanotubes. Adopting a diphenylalanine channel as a prototypical example, we find that the primary step in the dissociation process occurs due to the strong resonance between the carboxylate bond vibrations of the diphenylalanine peptides and the tuned laser frequencies. The effects of laser irradiation are determined by a balance between tube formation and dissociation. Our work shows a proof of concept and should provide a motivation for future experimental developments with the final aim to open a new and efficient way to cleave or to recycle bio-inspired materials.

  4. 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.

  5. 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.

  6. Study of picosecond processes of an intercalated dipyridophenazine Cr(III) complex bound to defined sequence DNAs using transient absorption and time-resolved infrared methods.

    PubMed

    Devereux, Stephen J; Keane, Páraic M; Vasudevan, Suni; Sazanovich, Igor V; Towrie, Michael; Cao, Qian; Sun, Xue-Zhong; George, Michael W; Cardin, Christine J; Kane-Maguire, Noel A P; Kelly, John M; Quinn, Susan J

    2014-12-21

    Picosecond transient absorption (TA) and time-resolved infrared (TRIR) measurements of rac-[Cr(phen)2(dppz)](3+) () intercalated into double-stranded guanine-containing DNA reveal that the excited state is very rapidly quenched. As no evidence was found for the transient electron transfer products, it is proposed that the back electron transfer reaction must be even faster (<3 ps).

  7. Applications of infrared free electron lasers in picosecond and nonlinear spectroscopy

    NASA Astrophysics Data System (ADS)

    Fann, W. S.; Benson, S. V.; Madey, J. M. J.; Etemad, S.; Baker, G. L.; Rothberg, L.; Roberson, M.; Austin, R. H.

    1990-10-01

    In this paper we describe two different types of spectroscopic experiments that exploit the characteristics of the infrared FEL, Mark III, for studies of condensed matter: - the spectrum of χ(3)(-3ω; ω, ω, ω) in polyacetylene: an application of the free electron laser in nonlinear optical spectroscopy, and - a dynamical test of Davydov-like solitons in acetanilide using a picosecond free electron laser. These two studies highlight the unique contributions FELs can make to condensed-matter spectroscopy.

  8. A New Technology for Applanation Free Corneal Trephination: The Picosecond Infrared Laser (PIRL)

    PubMed Central

    Linke, Stephan J.; Frings, Andreas; Ren, Ling; Gomolka, Amadeus; Schumacher, Udo; Reimer, Rudolph; Hansen, Nils-Owe; Jowett, Nathan; Richard, Gisbert; Miller, R. J. Dwayne

    2015-01-01

    The impact of using a Femtosecond laser on final functional results of penetrating keratoplasty is low. The corneal incisions presented here result from laser ablations with ultrafast desorption by impulsive vibrational excitation (DIVE). The results of the current study are based on the first proof-of-principle experiments using a mobile, newly introduced picosecond infrared laser system, and indicate that wavelengths in the mid-infrared range centered at 3 μm are efficient for obtaining applanation-free deep cuts on porcine corneas. PMID:25781907

  9. 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

  10. 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.

  11. Picosecond infrared laser (PIRL): an ideal phonomicrosurgical laser?

    PubMed

    Hess, Markus; Hildebrandt, Michael Dominik; Müller, Frank; Kruber, Sebastian; Kroetz, Peter; Schumacher, Udo; Reimer, Rudolph; Kammal, Michael; Püschel, Klaus; Wöllmer, Wolfgang; Miller, Dwayne

    2013-11-01

    A comparison of tissue cutting effects in excised cadaver human vocal folds after incisions with three different instruments [scalpel, CO2 laser and the picosecond infrared laser-(PIRL)] was performed. In total, 15 larynges were taken from human cadavers shortly after death. After deep freezing and thawing for the experiment, the vocal folds suspended in the hemilarynx were incised. Histology and environmental scanning electron microscopy (ESEM) analyses were performed. Damage zones after cold instrument cuts ranged from 51 to 135 μm, as compared to 9-28 μm after cutting with the PIRL. It was shown that PIRL incision had smaller zones of tissue coagulation and tissue destruction, when compared with scalpel and CO2 laser cuts. The PIRL technology provides an (almost) atraumatic laser, which offers a quantum jump towards realistic 'micro'-phonosurgery on a factual cellular dimension, almost entirely avoiding coagulation, carbonization, or other ways of major tissue destruction in the vicinity of the intervention area. Although not available for clinical use yet, the new technique appears promising for future clinical applications, so that technical and methodological characteristics as well as tissue experiments seem worthwhile to be communicated at this stage of development. PMID:23708442

  12. Picosecond infrared laser (PIRL): an ideal phonomicrosurgical laser?

    PubMed

    Hess, Markus; Hildebrandt, Michael Dominik; Müller, Frank; Kruber, Sebastian; Kroetz, Peter; Schumacher, Udo; Reimer, Rudolph; Kammal, Michael; Püschel, Klaus; Wöllmer, Wolfgang; Miller, Dwayne

    2013-11-01

    A comparison of tissue cutting effects in excised cadaver human vocal folds after incisions with three different instruments [scalpel, CO2 laser and the picosecond infrared laser-(PIRL)] was performed. In total, 15 larynges were taken from human cadavers shortly after death. After deep freezing and thawing for the experiment, the vocal folds suspended in the hemilarynx were incised. Histology and environmental scanning electron microscopy (ESEM) analyses were performed. Damage zones after cold instrument cuts ranged from 51 to 135 μm, as compared to 9-28 μm after cutting with the PIRL. It was shown that PIRL incision had smaller zones of tissue coagulation and tissue destruction, when compared with scalpel and CO2 laser cuts. The PIRL technology provides an (almost) atraumatic laser, which offers a quantum jump towards realistic 'micro'-phonosurgery on a factual cellular dimension, almost entirely avoiding coagulation, carbonization, or other ways of major tissue destruction in the vicinity of the intervention area. Although not available for clinical use yet, the new technique appears promising for future clinical applications, so that technical and methodological characteristics as well as tissue experiments seem worthwhile to be communicated at this stage of development.

  13. Picosecond Optical Studies of Solids.

    NASA Astrophysics Data System (ADS)

    Broomfield, Seth Emlyn

    Available from UMI in association with The British Library. Requires signed TDF. Hot carrier relaxation is studied in the alloy semiconductor Ga_{rm 1-x} Al_{rm x}As by analysis of time-resolved luminescence at 4K. Photoexcited carrier densities in the range 10^{16 } to 10^{18}cm ^{-3} were created by 5ps laser pulses in alloys with x values ranging from 0 to 0.36. Carrier temperature cooling curves are discussed in terms of emission and absorption of non-equilibrium phonons by carriers, intervalley scattering of electrons and alloy disorder effects. Energy relaxation within a band of localised exciton states is studied in Ga_{rm 1 -x}Al_{rm x} As by analysis of time-resolved photoluminescence at 4K with a photoexcited carrier density of 10 ^{14}cm^{-3 }. It is found that the width of the band of localised states increases with the degree of alloy disorder as x ranges from 0 to 0.36. A form for the density of localised states is obtained. The intersite exciton overlap is estimated. Photoluminescence of the semiconductor gallium selenide is measured for carrier densities below 3 times 10^{18}cm ^{-3} at 2K. Biexcitons are identified by analysis of the photoluminescence at high densities. This is confirmed by induced optical absorption experiments. It is shown that biexciton dissociation by interaction with low-energy optical phonons occurs as the lattice temperature is increased. The group velocity of excitonic polaritons is obtained from measurements of the time-of-flight of 5ps optical pulses across a 1mum thick layer of gallium arsenide at 4K. The group velocity has a minimum value of 4 times 10 ^5ms^{-1} at the transverse exciton energy, and has a dependence on photon energy which agrees well with a model describing spatial dispersion of polaritons.

  14. Time-resolved fluorescence polarization spectroscopy of visible and near infrared dyes in picosecond dynamics

    NASA Astrophysics Data System (ADS)

    Pu, Yang; Alfano, Robert R.

    2015-03-01

    Near-infrared (NIR) dyes absorb and emit light within the range from 700 to 900 nm have several benefits in biological studies for one- and/or two-photon excitation for deeper penetration of tissues. These molecules undergo vibrational and rotational motion in the relaxation of the excited electronic states, Due to the less than ideal anisotropy behavior of NIR dyes stemming from the fluorophores elongated structures and short fluorescence lifetime in picosecond range, no significant efforts have been made to recognize the theory of these dyes in time-resolved polarization dynamics. In this study, the depolarization of the fluorescence due to emission from rotational deactivation in solution will be measured with the excitation of a linearly polarized femtosecond laser pulse and a streak camera. The theory, experiment and application of the ultrafast fluorescence polarization dynamics and anisotropy are illustrated with examples of two of the most important medical based dyes. One is NIR dye, namely Indocyanine Green (ICG) and is compared with Fluorescein which is in visible range with much longer lifetime. A set of first-order linear differential equations was developed to model fluorescence polarization dynamics of NIR dye in picosecond range. Using this model, the important parameters of ultrafast polarization spectroscopy were identified: risetime, initial time, fluorescence lifetime, and rotation times.

  15. Mitotic spindle studied using picosecond laser scissors

    NASA Astrophysics Data System (ADS)

    Baker, N. M.; Botvinick, E. L.; Shi, Linda; Berns, M. B.; Wu, George

    2006-08-01

    In previous studies we have shown that the second harmonic 532 nm, from a picosecond frequency doubled Nd:YAG laser, can cleanly and selectively disrupt spindle fiber microtubules in live cells (Botvinick et al 2004, Biophys. J. 87:4303-4212). In the present study we have ablated different locations and amounts of the metaphase mitotic spindle, and followed the cells in order to observe the fate of the irradiated spindle and the ability of the cell to continue through mitosis. Cells of the rat kangaroo line (PTK2) were stably transfected by ECFP-tubulin and, using fluorescent microscopy and the automated RoboLase microscope, (Botvinick and Berns, 2005, Micros. Res. Tech. 68:65-74) brightly fluorescent individual cells in metaphase were irradiated with 0.2447 nJ/micropulse corresponding to an irradiance of 1.4496*10^7 J/(ps*cm^2) . Upon irradiation the exposed part of the mitotic spindle immediately lost fluorescence and the following events were observed in the cells over time: (1) immediate contraction of the spindle pole towards the cut, (2) recovery of connection between pole and cut microtubule, (3) completion of mitosis. This system should be very useful in studying internal cellular dynamics of the mitotic spindle.

  16. Resonant infrared ablation of polystyrene with single picosecond pulses generated by an optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Duering, Malte; Haglund, Richard; Luther-Davies, Barry

    2014-01-01

    We report on resonant infrared laser ablation of polystyrene using single 8 ps pulses at a wavelength of 3.31 μm generated by a MgO:PPLN optical parametric amplifier pumped by a Nd:YLF laser. We determined the single-pulse ablation threshold to be 0.46 J/cm2, about a factor of five smaller than in previous free-electron-laser studies. Time-resolved imaging of the laser-target interaction reveals that the detailed dynamics of the ablation process begin with thermal expansion of a large volume of hot material from which a less dense plume of polymeric material evaporates. This plume disappears on a time scale of 0.75 μs and the hot polymer material recedes back into the crater from which it was expelled. Subsequently, and on a much longer time scale, structural alterations in the ablation crater continue to evolve for at least another millisecond. Our results suggest that single picosecond pulses are effective for the ablation of polymers and exhibit dynamics similar to those observed in studies using a free-electron laser.

  17. Reduction of thermocoagulative injury via use of a picosecond infrared laser (PIRL) in laryngeal tissues.

    PubMed

    Böttcher, Arne; Kucher, Stanislav; Knecht, Rainald; Jowett, Nathan; Krötz, Peter; Reimer, Rudolph; Schumacher, Udo; Anders, Sven; Münscher, Adrian; Dalchow, Carsten V; Miller, R J Dwayne

    2015-04-01

    The carbon dioxide (CO2) laser is routinely used in glottic microsurgery for the treatment of benign and malignant disease, despite significant collateral thermal damage secondary to photothermal vaporization without thermal confinement. Subsequent tissue response to thermal injury involves excess collagen deposition resulting in scarring and functional impairment. To minimize collateral thermal injury, short-pulse laser systems such as the microsecond pulsed erbium:yttrium-aluminium-garnet (Er:YAG) laser and picosecond infrared laser (PIRL) have been developed. This study compares incisions made in ex vivo human laryngeal tissues by CO2 and Er:YAG lasers versus PIRL using light microscopy, environmental scanning electron microscopy (ESEM), and infrared thermography (IRT). In comparison to the CO2 and Er:YAG lasers, PIRL incisions showed significantly decreased mean epithelial (59.70 µm) and subepithelial (22.15 µm) damage zones (p < 0.05). Cutting gaps were significantly narrower for PIRL (133.70 µm) compared to Er:YAG and CO2 lasers (p < 0.05), which were more than 5 times larger. ESEM revealed intact collagen fibers along PIRL cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 and Er:YAG laser incisions. IRT demonstrated median temperature rise of 4.1 K in PIRL vocal fold incisions, significantly less than for Er:YAG laser cuts (171.85 K; p < 0.001). This study has shown increased cutting precision and reduced lateral thermal damage zones for PIRL ablation in comparison to conventional CO2 and Er:YAG lasers in human glottis and supraglottic tissues.

  18. Octave-spanning infrared supercontinuum generation in robust chalcogenide nanotapers using picosecond pulses.

    PubMed

    Shabahang, Soroush; Marquez, Michael P; Tao, Guangming; Piracha, Mohammad U; Nguyen, Dat; Delfyett, Peter J; Abouraddy, Ayman F

    2012-11-15

    We report on infrared supercontinuum generation extending over more than one octave of bandwidth, from 850 nm to 2.35 μm, produced in a single spatial mode from a robust, compact, composite chalcogenide glass nanotaper. A picosecond laser at 1.55 μm pumps a high-index-contrast, all-solid nanotaper that strongly confines the field to a 480 nm diameter core, while a thermally compatible built-in polymer jacket lends the nanotaper mechanical stability. PMID:23164864

  19. Ambient Mass Spectrometry Imaging with Picosecond Infrared Laser Ablation Electrospray Ionization (PIR-LAESI).

    PubMed

    Zou, Jing; Talbot, Francis; Tata, Alessandra; Ermini, Leonardo; Franjic, Kresimir; Ventura, Manuela; Zheng, Jinzi; Ginsberg, Howard; Post, Martin; Ifa, Demian R; Jaffray, David; Miller, R J Dwayne; Zarrine-Afsar, Arash

    2015-12-15

    A picosecond infrared laser (PIRL) is capable of cutting through biological tissues in the absence of significant thermal damage. As such, PIRL is a standalone surgical scalpel with the added bonus of minimal postoperative scar tissue formation. In this work, a tandem of PIRL ablation with electrospray ionization (PIR-LAESI) mass spectrometry is demonstrated and characterized for tissue molecular imaging, with a limit of detection in the range of 100 nM for reserpine or better than 5 nM for verapamil in aqueous solution. We characterized PIRL crater size using agar films containing Rhodamine. PIR-LAESI offers a 20-30 μm vertical resolution (∼3 μm removal per pulse) and a lateral resolution of ∼100 μm. We were able to detect 25 fmol of Rhodamine in agar ablation experiments. PIR-LAESI was used to map the distribution of endogenous methoxykaempferol glucoronide in zebra plant (Aphelandra squarrosa) leaves producing a localization map that is corroborated by the literature. PIR-LAESI was further used to image the distribution inside mouse kidneys of gadoteridol, an exogenous magnetic resonance contrast agent intravenously injected. Parallel mass spectrometry imaging (MSI) using desorption electrospray ionization (DESI) and matrix assisted laser desorption ionization (MALDI) were performed to corroborate PIR-LAESI images of the exogenous agent. We further show that PIR-LAESI is capable of desorption ionization of proteins as well as phospholipids. This comparative study illustrates that PIR-LAESI is an ion source for ambient mass spectrometry applications. As such, a future PIRL scalpel combined with secondary ionization such as ESI and mass spectrometry has the potential to provide molecular feedback to guide PIRL surgery. PMID:26561279

  20. Ambient Mass Spectrometry Imaging with Picosecond Infrared Laser Ablation Electrospray Ionization (PIR-LAESI).

    PubMed

    Zou, Jing; Talbot, Francis; Tata, Alessandra; Ermini, Leonardo; Franjic, Kresimir; Ventura, Manuela; Zheng, Jinzi; Ginsberg, Howard; Post, Martin; Ifa, Demian R; Jaffray, David; Miller, R J Dwayne; Zarrine-Afsar, Arash

    2015-12-15

    A picosecond infrared laser (PIRL) is capable of cutting through biological tissues in the absence of significant thermal damage. As such, PIRL is a standalone surgical scalpel with the added bonus of minimal postoperative scar tissue formation. In this work, a tandem of PIRL ablation with electrospray ionization (PIR-LAESI) mass spectrometry is demonstrated and characterized for tissue molecular imaging, with a limit of detection in the range of 100 nM for reserpine or better than 5 nM for verapamil in aqueous solution. We characterized PIRL crater size using agar films containing Rhodamine. PIR-LAESI offers a 20-30 μm vertical resolution (∼3 μm removal per pulse) and a lateral resolution of ∼100 μm. We were able to detect 25 fmol of Rhodamine in agar ablation experiments. PIR-LAESI was used to map the distribution of endogenous methoxykaempferol glucoronide in zebra plant (Aphelandra squarrosa) leaves producing a localization map that is corroborated by the literature. PIR-LAESI was further used to image the distribution inside mouse kidneys of gadoteridol, an exogenous magnetic resonance contrast agent intravenously injected. Parallel mass spectrometry imaging (MSI) using desorption electrospray ionization (DESI) and matrix assisted laser desorption ionization (MALDI) were performed to corroborate PIR-LAESI images of the exogenous agent. We further show that PIR-LAESI is capable of desorption ionization of proteins as well as phospholipids. This comparative study illustrates that PIR-LAESI is an ion source for ambient mass spectrometry applications. As such, a future PIRL scalpel combined with secondary ionization such as ESI and mass spectrometry has the potential to provide molecular feedback to guide PIRL surgery.

  1. Surfaces and thin films studied by picosecond ultrasonics

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse ( pump pulse''). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  2. Picosecond-time-resolved studies of nonradiative relaxation in ruby and alexandrite

    SciTech Connect

    Gayen, S.K.; Wang, W.B.; Petricevic, V.; Alfano, R.R.

    1985-01-01

    Dynamics of the nonradiative transitions between the /sup 4/T/sub 2/ pump band and the /sup 2/E storage level of the Cr/sup 3 +/ ion in ruby and alexandrite crystals is studied using the picosecond excite-and-probe absorption technique. A 527-nm picosecond pulse excites the /sup 4/T/sub 2/ state of the Cr/sup 3 +/ ion, and an infrared picosecond probe pulse monitors the subsequent growth and decay of population in the excited states as a function of pump-probe delay. An upper limit of 7 ps is determined for the nonradiative lifetime of the /sup 4/T/sub 2/ state in ruby. A vibrational relaxation time of 25 ps for the /sup 4/T/sub 2/ band in alexandrite is estimated. The time to attain thermal equilibrium population between the /sup 2/E and /sup 4/T/sub 2/ levels of alexandrite following excitation of /sup 4/T/sub 2/ band is estimated to be approx. 100 ps.

  3. Peak power tunable mid-infrared oscillator pumped by a high power picosecond pulsed fiber amplifier with bunch output

    NASA Astrophysics Data System (ADS)

    Wei, Kaihua; Guo, Yan; Lai, Xiaomin; Fan, Shanhui

    2016-07-01

    A high power mid-infrared optical parametric oscillator (OPO) with picosecond pulse bunch output is experimentally demonstrated. The pump source was a high power master oscillation power amplifier (MOPA) picosecond pulsed fiber amplifier. The seed of the MOPA was a gain-switched distributed Bragg reflector (DBR) laser diode (LD) with picosecond pulse operation at a high repetition rate. The seed laser was amplified to 50 W by two-stage pre-amplifiers and a large mode area (LMA) Yb fiber based power-amplifier. A fiber-pigtailed acousto-optic modulator with the first order diffraction transmission was inserted into the second pre-amplifier to form a picosecond pulse bunch train and to change the peak power simultaneously. The power-amplified pulse bunches were focused to pump a wavelength-tunable OPO for emitting high power mid-infrared laser. By adjusting the OPO cavity length, the maximum average idler powers obtained at 3.1, 3.3 and 3.5 μm were 7, 6.6 and 6.4 W respectively.

  4. Excited state dynamics and activation parameters of remarkably slow photoinduced CO loss from (η⁶-benzene)Cr(CO)₃ in n-heptane solution: a DFT and picosecond-time-resolved infrared study.

    PubMed

    Clark, Ian P; George, Michael W; Greetham, Gregory M; Harvey, Emma C; Long, Conor; Manton, Jennifer C; Pryce, Mary T

    2010-11-01

    The electronic structure of (η⁶-benzene)Cr(CO)₃ has been calculated using density functional theory and a molecular orbital interaction diagram constructed based on the Cr(CO)₃ and benzene fragments. The highest occupied molecular orbitals are mainly metal based. The nature of the lowest energy excited states were determined by time-dependent density functional theory, and the lowest energy excited state was found to have significant metal to carbonyl charge transfer character. The photochemistry of (η⁶-benzene)Cr(CO)₃ was investigated by time-resolved infrared spectroscopy with picosecond time resolution. The low energy excited state was detected following irradiation at 400 nm, and this exhibited ν(CO) bands at lower energy than the equivalent ν(CO) bands of (η⁶-benzene)Cr(CO)₃, consistent with metal to carbonyl charge transfer character, and is formed with excess vibrational energy, relaxing to the v = 0 vibrational state within 3 ps. The resulting "cold" excited state decays to form the CO-loss species (η⁶-benzene)Cr(CO)₂ in approximately 70% yield and to reform (η⁶-benzene)Cr(CO)₃ within 150 ps. The rates of relaxation from the vibrationally hot state to the cold excited state and its subsequent reaction to yield (η⁶-benzene)Cr(CO)₂ were measured over a range of temperatures from 274 to 320 K, and the activation parameters for both processes were obtained from Eyring plots. The vibrational relaxation exhibits a negative activation enthalpy ΔH(‡) (-10 (±4) kJ mol⁻¹) and a negative activation entropy ΔS(‡) (-50 (±16) J mol⁻¹ K⁻¹). A significant barrier (ΔH(‡) = +12 (±4) kJ mol⁻¹) was obtained for the formation of (η⁶-benzene)Cr(CO)₂ with a ΔS(‡) value close to zero. These data are used to propose a model for the CO-loss process to yield (η⁶-benzene)Cr(CO)₂ and to explain why low temperature irradiation of (η⁶-benzene)Cr(CO)₃ with light of wavelengths greater than 400 nm produced

  5. (Surfaces and thin films studied by picosecond ultrasonics)

    SciTech Connect

    Maris, H.J.; Tauc, J.

    1990-01-01

    This research supported by grant FG02-86ER45367 is the study of the properties of solids by means of the picosecond technique. In this research we investigate both fundamental problems in phonon physics and lattice dynamics, and we also apply the technique to the non-destructive evaluation of thin-film microstructures. In the experiments a picosecond light pulse is absorbed at a surface, thereby generating an elastic pulse. This strain pulse propagates through the sample, and is detected at a later time by means of a time-delayed probe light pulse. During the past year our research has been concentrated in three main areas. We have made an extensive series of measurements of ultrasonic attenuation as a function of frequency and temperature in glasses. We have succeeded in generating and detecting surface acoustic waves in microstructures with surface gratings and dot arrays, and have performed several experiments to study the structure of thin films and surface layers. The third area is the investigation of heat flow from metal films into dielectric crystals, and the possible observation of second sound. Also included is the proposal for next years work. 7 refs., 3 figs.

  6. Retinal threshold studies for nanosecond and picosecond visible laser pulses

    NASA Astrophysics Data System (ADS)

    Roach, William P.; DiCarlo, Cheryl D.; Noojin, Gary D.; Stolarski, David J.; Amnotte, Rodney E.; Smith, Audrey B.; Rogers, Mark E.; Cain, Clarence P.

    1995-05-01

    Threshold measurements for Minimum Visible Lesions (MVL) at the retina are reported for 60 picoseconds (ps) and 4 nanoseconds (ns), single laser pulses in rhesus monkey eyes using a visible wavelength of 532 nanometers (nm) from a doubled Nd:YAG laser. The 50% probability for damage (ED50) dosages are calculated for 1 hour and 24 hour post exposures using 95% fiducial limits. For both pulsewidths, the threshold values calculated by probit analysis decrease between the 1 hour and 24 hour ophthalmoscopic evaluations. The ED50 value determined for the 60 ps pulsewidth was less than half the value at 4 ns (0.43 (mu) J/60 ps vs. 0.90 (mu) J/4 ns at 24 hours) for both readings. Of the 136 exposures for pulse energies ranging from 0.03 to 5.0 (mu) J no hemorrhagic lesions were produced for either pulsewidth studied. However, at 6.6 (mu) J one intraretinal hemorrhagic lesion was observed for 60 ps. The slope of the probit curve was higher for 60 ps when compared with the 4 ns value (3.03 at 60 ps vs. 2.68 at 4 ns). MVL threshold doses calculated are comparable with those reported in the literature. However, the 4 ns MVL values is less than one order of magnitude (a factor 4.7) above the Maximum Permissible Exposure (MPE) level as defined by the 'American National Standard For The Safe Use Of Lasers', ANSI Z136.1-19932. We present the current MVL data as it compares with previous data obtained for picosecond and femtosecond laser pulse thresholds and provide a preliminary assessment of how the ANSI MPE standard might be amended.

  7. Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

    2016-03-01

    In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, <=50um with ps laser, and <=20um with sub-ps laser, respectively was observed as a criteria of selecting the laser pulse width. The effects of laser processing parameters on speed and efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

  8. Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1982-01-01

    Spectroscopic and excited state decay kinetics are reported for monomeric and polymeric forms of ultraviolet stabilizers in the 2-(2'-hydroxyphenyl)-benzotriazole and 2-hydroxybenzophenone classes. For some of these molecules in various solvents at room temperature, (1) ground state absorption spectra, (2) emission spectra, (3) picosecond time-resolved transient absorption spectra, (4) ground state absorption recovery kinetics, (5) emission kinetics, and (6) transient absorption kinetics are reported. In the solid state at low temperatures, emission spectra and their temperature dependent kinetics up to approximately 200K as well as, in one case, the 12K excitation spectra of the observed dual emission are also reported.

  9. Millijoule-level picosecond mid-infrared optical parametric amplifier based on MgO-doped periodically poled lithium niobate.

    PubMed

    Xu, Hongyan; Yang, Feng; Chen, Ying; Liu, Ke; Du, Shifeng; Zong, Nan; Yang, Jing; Bo, Yong; Peng, Qinjun; Zhang, Jingyuan; Cui, Dafu; Xu, Zuyan

    2015-03-20

    A millijoule-level high pulse energy picosecond (ps) mid-infrared (MIR) optical parametric amplifier (OPA) at 3.9 μm based on large-aperture MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal was demonstrated for the first time, to the best of our knowledge. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser at 10 Hz and injected by an energy-adjustable near-infrared seed based on a barium boron oxide (BBO) optical parametric generator/optical parametric amplifier (OPG/OPA) with double-pass geometry. Output energy of 1.14 mJ at 3.9 μm has been obtained at pump energy of 15.2 mJ. Furthermore, the performance of MIR OPG in MgO:PPLN was also investigated for comparing with the seeded OPA.

  10. Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy.

    PubMed

    Elias, Benjamin; Creely, Caitriona; Doorley, Gerard W; Feeney, Martin M; Moucheron, Cécile; Kirsch-DeMesmaeker, Andrée; Dyer, Joanne; Grills, David C; George, Michael W; Matousek, Pavel; Parker, Anthony W; Towrie, Michael; Kelly, John M

    2008-01-01

    Transient species formed by photoexcitation (400 nm) of [Ru(dppz)(tap)2]2+ (1) (dppz = dipyrido[3,2-a:2',3'-c]phenazine; tap=1,4,5,8-tetraazaphenanthrene) in aqueous solution and when intercalated into a double-stranded synthetic polynucleotide, [poly(dG-dC)]2, have been observed on a picosecond timescale by both visible transient absorption (allowing monitoring of the metal complex intermediates) and transient infrared (IR) absorption spectroscopy (allowing direct study of the DNA nucleobases). By contrast with its behavior when free in aqueous solution, excitation of 1 when bound to [poly(dG-dC)]2 causes a strong increase in absorbance at 515 nm due to formation of the reduced complex [Ru(dppz)(tap)2]+ (rate constant=(2.0+/-0.2) x 10(9) s(-1)). The subsequent reformation of 1 proceeds with a rate constant of (1.1+/-0.2) x 10(8) s(-1). When the process is carried out in D2O, the rates of formation and removal of [Ru(dppz)(tap)2]+ are reduced (rate constants (1.5+/-0.3) x 10(9) and (0.7+/-0.2) x 10(8) s(-1) respectively) consistent with proton-coupled electron transfer processes. Picosecond transient IR measurements in the 1540-1720 cm(-1) region in D2O solution confirm that the reduction of 1 intercalated into [poly(dG-dC)]2 is accompanied by bleaching of IR ground-state bands of guanine (1690 cm(-1)) and cytosine (1656 cm(-1)), each with similar rate constants.

  11. 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.

  12. Ultrafast charge separation in a photoreactive rhenium-appended porphyrin assembly monitored by picosecond transient infrared spectroscopy.

    PubMed

    Gabrielsson, Anders; Hartl, Frantisek; Zhang, Hong; Lindsay Smith, John R; Towrie, Michael; Vlcek, Antonín; Perutz, Robin N

    2006-04-01

    Rhenium(bipyridine)(tricarbonyl)(picoline) units have been linked covalently to tetraphenylmetalloporphyrins of magnesium and zinc via an amide bond between the bipyridine and one phenyl substituent of the porphyrin. The resulting complexes, abbreviated as [Re(CO)(3)(Pic)Bpy-MgTPP][OTf] and [Re(CO)(3)(Pic)Bpy-ZnTPP][OTf], exhibit no signs of electronic interaction between the Re(CO)(3)(bpy) units and the metalloporphyrin units in their ground states. However, emission spectroscopy reveals solvent-dependent quenching of porphyrin emission on irradiation into the long-wavelength absorption bands localized on the porphyrin. The characteristics of the excited states have been probed by picosecond time-resolved absorption (TRVIS) spectroscopy and time-resolved infrared (TRIR) spectroscopy in nitrile solvents. The presence of the charge-separated state involving electron transfer from MgTPP or ZnTPP to Re(bpy) is signaled in the TRIR spectra by a low-frequency shift in the nu(CO) bands of the Re(CO)(3) moiety similar to that observed by spectroelectrochemical reduction. Long-wavelength excitation of [Re(CO)(3)(Pic)Bpy-MTPP][OTf] results in characteristic TRVIS spectra of the S(1) state of the porphyrin that decay with a time constant of 17 ps (M = Mg) or 24 ps (M = Zn). The IR bands of the CS state appear on a time scale of less than 1 ps (Mg) or ca. 5 ps (Zn) and decay giving way to a vibrationally excited (i.e., hot) ground state via back electron transfer. The IR bands of the precursors recover with a time constant of 35 ps (Mg) or 55 ps (Zn). The short lifetimes of the charge-transfer states carry implications for the mechanism of reaction in the presence of triethylamine.

  13. Surfaces and thin films studied by picosecond ultrasonics. Progress report, December 1, 1989--November 30, 1992

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse (``pump pulse``). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  14. Picosecond optical limiting in reverse saturable absorbers: a theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Lepkowicz, Richard; Kobyakov, Andrey; Hagan, David J.; van Stryland, Eric W.

    2002-01-01

    We theoretically and experimentally study absorption of picosecond laser pulses in materials described by a four-level system that exhibit reverse saturable absorption (RSA). Using an approximate solution to the rate equations, we derive, analyze, and verify, numerically and experimentally, a single dynamical equation for the spatial evolution of the pulse fluence that includes both the rate equations and the propagation equation. This analytical approach considerably simplifies the study of optical limiting with picosecond pulses and helps to predict the behavior of the nonlinear transmittance, the level of output signal clamping, and a possible turnover from RSA to saturable absorption that restricts the performance of optical limiters based on RSA. The results obtained can also be used to characterize RSA materials by the pump-probe technique.

  15. Toward picosecond time-resolved X-ray absorption studies of interfacial photochemistry

    NASA Astrophysics Data System (ADS)

    Gessner, Oliver; Mahl, Johannes; Neppl, Stefan

    2016-05-01

    We report on the progress toward developing a novel picosecond time-resolved transient X-ray absorption spectroscopy (TRXAS) capability for time-domain studies of interfacial photochemistry. The technique is based on the combination of a high repetition rate picosecond laser system with a time-resolved X-ray fluorescent yield setup that may be used for the study of radiation sensitive materials and X-ray spectroscopy compatible photoelectrochemical (PEC) cells. The mobile system is currently deployed at the Advanced Light Source (ALS) and may be used in all operating modes (two-bunch and multi-bunch) of the synchrotron. The use of a time-stamping technique enables the simultaneous recording of TRXAS spectra with delays between the exciting laser pulses and the probing X-ray pulses spanning picosecond to nanosecond temporal scales. First results are discussed that demonstrate the viability of the method to study photoinduced dynamics in transition metal-oxide semiconductor (SC) samples under high vacuum conditions and at SC-liquid electrolyte interfaces during photoelectrochemical water splitting. Opportunities and challenges are outlined to capture crucial short-lived intermediates of photochemical processes with the technique. This work was supported by the Department of Energy Office of Science Early Career Research Program.

  16. Picosecond infrared spectroscopy as probe for photochemical or thermal reactions in solid matrices

    SciTech Connect

    Lippert, T.; Funk, D.J.; Strauss, C.E.M.; Stoutland, P.O.

    1998-08-01

    Spectroscopy in the mid-IR on timescales from pico to milliseconds has been developed for the study of laser-material interactions over broad timescales. To reach these timescales the authors have employed two configurations: (1) for the ps to ns timescale a one and a two stage difference frequency mixing setup is employed, (2) for the longer timescale, CW mid-IR laser diodes have been used. In general, they excite the sample with one pulse at 1064/266/355 nm and probe some time later in the mid IR (2900--800 cm{sup {minus}1}). In the case of photochemical reaction, they excite the sample directly in the UV. Alternatively, they initiate thermal reactions by pumping a heater dye at 1.064 {micro}m, which quickly converts the photon energy into heat. The potential of this technique to study reactions in the solid state was demonstrated for a photochemically induced (266 nm) reaction (Wolff rearrangement of a {alpha}-diazo-ketone to {alpha}-keto-ketene) in a polymer matrix. Thermal initiation resulted in a similar reaction. The position, amplitude and width of the product bands changed, they believe due to additional side reactions and temperature effects.

  17. Picosecond dynamics of reactions in the liquid phase: studies of iodine photodissociation and development of new laser techniques

    SciTech Connect

    Berg, M.A.

    1985-09-01

    Iodine photodissociation and recombination was studied as a model for processes common to chemical reaction in the liquid phase. Picosecond transient absorption measurements from 1000 to 295 nm were used to monitor the dynamics in a variety of solvents. Most of the atoms which undergo geminate recombination were found to do so in less than or equal to 15 ps, in agreement with the results of existing molecular dynamics simulations. Vibrational relaxation times vary from approx.15 ps near the middle of the ground state well to approx.150 ps for complete relaxation to v = 0. The prediction of strong resonant vibrational energy transfer to chlorinated methane solvents was not supported, but some evidence for this mechanism was found for alkane solvents. Current theory is unable to explain the large variation (65 to 2700 ps) of the excited A'-state lifetime in various solvents. The 10-Hz amplified, synchronously-pumped dye laser which was used in these studies is described and characterized. SERS (Stimulated Electronic Raman Scattering) and difference frequency mixing were used in the generation of the infrared and far-infrared, respectively. 54 refs., 38 figs., 3 tabs. (WRF)

  18. High-power, mid-infrared, picosecond pulses generated by compression of a CO₂ laser beat-wave in GaAs.

    PubMed

    Pigeon, J J; Tochitsky, S Ya; Joshi, C

    2015-12-15

    We report on the generation of a train of ∼2  ps, 10 μm laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl crystals. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO₂ laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves, we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  19. Picosecond nonlinear optical studies of gold nanoparticles synthesised using coriander leaves (Coriandrum sativum)

    NASA Astrophysics Data System (ADS)

    Venugopal Rao, S.

    2011-07-01

    The results are presented from the experimental picosecond nonlinear optical (NLO) studies of gold nanoparticles synthesised using coriander leaf (Coriandrum sativum) extract. Nanoparticles with an average size of ∼30 nm (distribution of 5-70 nm) were synthesised according to the procedure reported by Narayanan et al. [Mater. Lett. 2008, 62, 4588-4591]. NLO studies were carried out using the Z-scan technique using 2 ps pulses near 800 nm. Open-aperture data suggested saturation absorption as the nonlinear absorption mechanism, whereas closed-aperture data suggested a positive nonlinearity. The magnitude of third-order nonlinearity was estimated to be (3.3 ± 0.6) × 10-13 esu. A solvent contribution to the nonlinearity was also identified and estimated. A comparison is attempted with some recently reported NLO studies of similar gold nanostructures.

  20. Picosecond charge transport in rutile at high carrier densities studied by transient terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Zajac, V.; Němec, H.; Kužel, P.

    2016-09-01

    We study terahertz photoconductivity of a rutile single crystal between 10 and 300 K under strong photoexcitation by femtosecond pulses at 266 nm. A marked dependence of the carrier mobility on the carrier density is observed leading to highly complex transport phenomena on a picosecond time scale. We develop a general model of carrier photoconductive response in the case of time dependent inhomogeneous distribution of carrier density and mobility. This allows us to assess an important role of both electrons and holes in the response of photoexcited rutile. At low temperatures, the carrier mobility is initially reduced due to the electron-hole scattering and increases by one order of magnitude upon ambipolar diffusion of the carriers into deeper regions of the sample. At room temperature, contributions of transient hot optical phonons and/or of midinfrared polaron excitations with charge-density-dependent dielectric strength emerge in the photoconductivity spectra.

  1. Mid-infrared picosecond pump-dump-probe and pump-repump-probe experiments to resolve a ground-state intermediate in cyanobacterial phytochrome Cph1.

    PubMed

    van Wilderen, Luuk J G W; Clark, Ian P; Towrie, Michael; van Thor, Jasper J

    2009-12-24

    Multipulse picosecond mid-infrared spectroscopy has been used to study photochemical reactions of the cyanobacterial phytochrome photoreceptor Cph1. Different photophysical schemes have been discussed in the literature to describe the pathways after photoexcitation, particularly, to identify reaction phases that are linked to photoisomerisation and electronic decay in the 1566-1772 cm(-1) region that probes C=C and C=O stretching modes of the tetrapyrrole chromophore. Here, multipulse spectroscopy is employed, where, compared to conventional visible pump-mid-infrared probe spectroscopy, an additional visible pulse is incorporated that interacts with populations that are evolving on the excited- and ground-state potential energy surfaces. The time delays between the pump and the dump pulse are chosen such that the dump pulse interacts with different phases in the reaction process. The pump and dump pulses are at the same wavelength, 640 nm, and are resonant with the Pr ground state as well as with the excited state and intermediates. Because the dump pulse additionally pumps the remaining, partially recovered, and partially oriented ground-state population, theory is developed for estimating the fraction of excited-state molecules. The calculations take into account the model-dependent ground-state recovery fraction, the angular dependence of the population transfer resulting from the finite bleach that occurs with linearly polarized intense femtosecond optical excitation, and the partially oriented population for the dump field. Distinct differences between the results from the experiments that use a 1 or a 14 ps dump time favor a branching evolution from S1 to an excited state or reconfigured chromophore and to a newly identified ground-state intermediate (GSI). Optical dumping at 1 ps shows the instantaneous induced absorption of a delocalized C=C stretching mode at 1608 cm(-1), where the increased cross section is associated with the electronic ground

  2. Single water solvation dynamics in the 4-aminobenzonitrile-water cluster cation revealed by picosecond time-resolved infrared spectroscopy.

    PubMed

    Miyazaki, Mitsuhiko; Nakamura, Takashi; Wohlgemuth, Matthias; Mitrić, Roland; Dopfer, Otto; Fujii, Masaaki

    2015-11-28

    The dynamics of a solvent is important for many chemical and biological processes. Here, the migration dynamics of a single water molecule is triggered by the photoionization of the 4-aminobenzonitrile-water (4ABN-W) cluster and monitored in real time by picosecond time-resolved IR (ps TRIR) spectroscopy. In the neutral cluster, water is hydrogen-bonded to the CN group. When this CN-bound cluster is selectively ionized with an excess energy of 1238 cm(-1), water migrates with a lifetime of τ = 17 ps from the CN to the NH2 group, forming a more stable 4ABN(+)-W(NH) isomer with a yield of unity. By decreasing the ionization excess energy, the yield of the CN → NH2 reaction is reduced. The relatively slow migration in comparison to the ionization-induced solvent dynamics in the related acetanilide-water cluster cation (τ = 5 ps) is discussed in terms of the internal excess energy after photoionization and the shape of the potential energy surface. PMID:26490096

  3. Infrared detection with high-[Tc] bolometers and response of Nb tunnel junctions to picosecond voltage pulses

    SciTech Connect

    Verghese, S.

    1993-05-01

    Oxide superconductors with high critical temperature [Tc] make sensitive thermometers for several types of infrared bolometers. The authors built composite bolometers with YBa[sub 2]Cu[sub 3]O[sub 7[minus][delta

  4. Optical tomography of human skin with subcellular spatial and picosecond time resolution using intense near infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Wollina, Uwe; Riemann, Iris; Peukert, Christiane; Halbhuber, Karl-Juergen; Konrad, Helga; Fischer, Peter; Fuenfstueck, Veronika; Fischer, Tobias W.; Elsner, Peter

    2002-06-01

    We describe the novel high resolution imaging tool DermaInspect 100 for non-invasive diagnosis of dermatological disorders based on multiphoton autofluorescence imaging (MAI)and second harmonic generation. Femtosecond laser pulses in the spectral range of 750 nm to 850 nm have been used to image in vitro and in vivo human skin with subcellular spatial and picosecond temporal resolution. The non-linear induced autofluorescence originates mainly from naturally endogenous fluorophores/protein structures like NAD(P)H, flavins, keratin, collagen, elastin, porphyrins and melanin. Second harmonic generation was observed in the stratum corneum and in the dermis. The system with a wavelength-tunable compact 80 MHz Ti:sapphire laser, a scan module with galvo scan mirrors, piezoelectric objective positioner, fast photon detector and time-resolved single photon counting unit was used to perform optical sectioning and 3D autofluorescence lifetime imaging (t-mapping). In addition, a modified femtosecond laser scanning microscope was involved in autofluorescence measurements. Tissues of patients with psoriasis, nevi, dermatitis, basalioma and melanoma have been investigated. Individual cells and skin structures could be clearly visualized. Intracellular components and connective tissue structures could be further characterized by tuning the excitation wavelength in the range of 750 nm to 850 nm and by calculation of mean fluorescence lifetimes per pixel and of particular regions of interest. The novel non-invasive imaging system provides 4D (x,y,z,t) optical biopsies with subcellular resolution and offers the possibility to introduce a further optical diagnostic method in dermatology.

  5. Microviscosity in polyacrylamide gels with pendant triphenyl-methane leuco derivatives: picosecond time-resolved fluorescence study

    NASA Astrophysics Data System (ADS)

    Tamai, Naoto; Ishikawa, Masazumi; Kitamura, Noboru; Masuhara, Hiroshi

    1991-10-01

    Picosecond fluorescence dynamics of triphenylmethane dyes bonded to polyacrylamide gels before and after swelling was studied by a single-photon timing technique. Microviscosity in the gels after swelling was estimated to be 10-11 cP by examining the viscosity dependence of fluorescence dynamics of malachite green in various alcohols. The results were interpreted in terms of structured stiff water in a microcavity of the gels.

  6. [Study of cancer cells fluorescence lifetime based on picosecond time resolution].

    PubMed

    Chen, Bi-Fang; Liu, Tian-Fu

    2006-08-01

    The object of the present study was the ultrafast photodynamic processes of hematoporphyrin derivative (HPD) for diagnosis and therapy of cancer. Time-resolved fluorescence spectra of cancerous and normal cells were measured using an ultrashort pulse laser spectral technique and picosecond time-correlated single-photon counting system. The fast part of cancerous and normal cells fluorescence decay was approximately 150 and 300 ps, the fluorescence peak intensity of cancerous and normal cells decayed about 10% and 55% in 12 hour, the lifetime of cancerous and normal cells was about 824 and 1 798 ps by calculating date of fluorescence decay, and HPD stay time was about 17 and 6 days in the cancerous and normal cells sample respectively. The data show that cancerous cells were greatly intimate with HPD. The results obtained can be used as an important basis for the diagnosis of cancer based on ultrashort pulse laser spectral technique. The results will contribute to feebleness ultrafast fluorescence of biology sample for real time measurement. PMID:17058959

  7. Study on third-order nonlinear optical properties of 4-methylsulfanyl chalcone derivatives using picosecond pulses

    SciTech Connect

    D'silva, E.D.; Podagatlapalli, G. Krishna; Venugopal Rao, S.; Dharmaprakash, S.M.

    2012-11-15

    Graphical abstract: Photograph and schematic representation of Z-scan experimental setup used to investigate third order nonlinear properties of the chalcone materials. Highlights: ► Br and NO{sub 2} substituted chalcone derivatives were exposed to picosecond laser pulses. ► Third-order nonlinear optical (NLO) properties were investigated. ► Compounds show promising third-order and optical limiting properties. ► These materials found suitable for electrical and optical applications. -- Abstract: In this paper we present results from the experimental study of third-order nonlinear optical (NLO) properties of three molecules of Br and NO{sub 2} substituted chalcone derivatives namely (2E)-1-(4-bromophenyl)-3-[4(methylsulfanyl)phenyl]prop-2-en-1-one (4Br4MSP), (2E)-1-(3-bromophenyl)-3-[4-(methylsulfanyl) phenyl]prop-2-en-1-one (3Br4MSP) and (2E)-3[4(methylsulfanyl) phenyl]-1-(4-nitrophenyl)prop-2-en-1-one (4N4MSP). The NLO properties have been investigated by Z-scan technique using 2 ps laser pulses at 800 nm. The nonlinear refractive indices, nonlinear absorption coefficient, and the magnitude of third-order susceptibility have been determined. The values obtained are of the order of 10{sup −7} cm{sup 2}/GW, 10{sup −3} cm/GW and 10{sup −14} esu respectively. The molecular second hyperpolarizability for the chalcone derivatives is of the order of 10{sup −32} esu. The coupling factor, excited state cross section, ground state cross section etc. were determined. The optical limiting (OL) property was studied. The results suggest that the nonlinear properties investigated for present chalcones are comparable with some of the reported chalcone derivatives and can be desirable for NLO applications.

  8. Infrared detection with high-{Tc} bolometers and response of Nb tunnel junctions to picosecond voltage pulses

    SciTech Connect

    Verghese, S.

    1993-05-01

    Oxide superconductors with high critical temperature {Tc} make sensitive thermometers for several types of infrared bolometers. The authors built composite bolometers with YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thermometers on sapphire substrates which have higher sensitivity than competing thermal detectors which operate at temperatures above 77 K. A 1 x 1 mm bolometer with gold black serving as the radiation absorber has useful sensitivity for wavelengths 20--100 {mu}m. A 3 x 3 mm bolometer with a bismuth film as the absorber operates from 20--100 {mu}m. High-{Tc} bolometers which are fabricated with micromachining techniques on membranes of Si or Si{sub 3}N{sub 4} have potential application to large-format arrays which are used for infrared imaging. A nonisothermal high-{Tc} bolometer can be fabricated on a membrane of yttria-stabilized zirconia (YSZ) which is in thermal contact with the heat sink along the perimeter of the membrane. A thermal analysis indicates that the YSZ membrane bolometer can have improved sensitivity compared to the sapphire bolometer for spectrometer applications. The quasiparticle tunneling current in a superconductor-insulator-superconductor (SIS) junction is highly nonlinear in the applied voltage. The authors have made the first measurement of the linear response of the quasiparticle current in a Nb/AlO{sub x}/Nb junction over a broad bandwidth from 75--200 GHz. Nonlinear measurements made with these pulses may provide information about the quasiparticle lifetime. Preliminary data from such measurements are presented.

  9. High power mid-infrared supercontinuum generation in a single-mode ZBLAN fiber pumped by amplified picosecond pulses at 2 μm

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Liu, Jiang; Shi, Hongxing; Tan, Fangzhou; Jiang, Yijian; Wang, Pu

    2015-03-01

    We report high power all fiber mid-infrared (mid-IR) supercontinuum (SC) generation in a single-mode ZBLAN (ZrF4- BaF2-LaF3-AlF3-NaF) fiber with up to 21.8 W average output power from 1.9 to beyond 3.8 μm pumped by amplified picosecond pulses from a master oscillator power amplifier (MOPA) based on small-core single-mode thulium-doped fiber (TDF) with injected seed pulse width of 24 ps and repetition of 93.6 MHz at 1963 nm. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage thulium-doped fiber amplifier (TDFA) to mid-IR SC output is 17%. It is, to the best of our knowledge, the highest average power mid-IR SC generation in a ZBLAN fiber to date. In addition, a noise-like fiber oscillator based on a nonlinear loop mirror (NOLM) with wavepacket width of ~1.4 ns and repetition rate of 3.36 MHz at 1966 nm is also used as a seed of the MOPA for mid-IR SC generation in the ZBLAN fiber. At last, a mid-IR SC from 1.9 to beyond 3.6 μm with average output power of 14.3W, which is limited by injected noise-like pulses power, is generated. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage TDFA to mid-IR SC output is 14.9%. This proves the amplified noise-like pulses are also appropriate for high power mid-IR SC generation in the ZBLAN fiber.

  10. Photoionization-induced π↔ H site switching dynamics in phenol(+)-Rg (Rg = Ar, Kr) dimers probed by picosecond time-resolved infrared spectroscopy.

    PubMed

    Miyazaki, Mitsuhiko; Sakata, Yuri; Schütz, Markus; Dopfer, Otto; Fujii, Masaaki

    2016-09-21

    The ionization-induced π↔ H site switching reaction in phenol(+)-Rg (PhOH(+)-Rg) dimers with Rg = Ar and Kr is traced in real time by picosecond time-resolved infrared (ps-TRIR) spectroscopy. The ps-TRIR spectra show the prompt appearance of the non-vanishing free OH stretching band upon resonant photoionization of the π-bound neutral clusters, and the delayed appearance of the hydrogen-bonded (H-bonded) OH stretching band. This result directly proves that the Rg ligand switches from the π-bound site on the aromatic ring to the H-bonded site at the OH group by ionization. The subsequent H →π back reaction converges the dimer to a π↔ H equilibrium. This result is in sharp contrast to the single-step π→ H forward reaction in the PhOH(+)-Ar2 trimer with 100% yield. The reaction mechanism and yield strongly depend on intracluster vibrational energy redistribution. A classical rate equation analysis for the time evolutions of the band intensities of the two vibrations results in similar estimates for the time constants of the π→ H forward reaction of τ+ = 122 and 73 ps and the H →π back reaction of τ- = 155 and 188 ps for PhOH(+)-Ar and PhOH(+)-Kr, respectively. The one order of magnitude slower time constant in comparison to the PhOH(+)-Ar2 trimer (τ+ = 7 ps) is attributed to the decrease in density of states due to the absence of the second Ar in the dimer. The similar time constants for both PhOH(+)-Rg dimers are well rationalized by a classical interpretation based on the comparable potential energy surfaces, reaction pathways, and density of states arising from their similar intermolecular vibrational frequencies. PMID:27550720

  11. Photoionization-induced π↔ H site switching dynamics in phenol(+)-Rg (Rg = Ar, Kr) dimers probed by picosecond time-resolved infrared spectroscopy.

    PubMed

    Miyazaki, Mitsuhiko; Sakata, Yuri; Schütz, Markus; Dopfer, Otto; Fujii, Masaaki

    2016-09-21

    The ionization-induced π↔ H site switching reaction in phenol(+)-Rg (PhOH(+)-Rg) dimers with Rg = Ar and Kr is traced in real time by picosecond time-resolved infrared (ps-TRIR) spectroscopy. The ps-TRIR spectra show the prompt appearance of the non-vanishing free OH stretching band upon resonant photoionization of the π-bound neutral clusters, and the delayed appearance of the hydrogen-bonded (H-bonded) OH stretching band. This result directly proves that the Rg ligand switches from the π-bound site on the aromatic ring to the H-bonded site at the OH group by ionization. The subsequent H →π back reaction converges the dimer to a π↔ H equilibrium. This result is in sharp contrast to the single-step π→ H forward reaction in the PhOH(+)-Ar2 trimer with 100% yield. The reaction mechanism and yield strongly depend on intracluster vibrational energy redistribution. A classical rate equation analysis for the time evolutions of the band intensities of the two vibrations results in similar estimates for the time constants of the π→ H forward reaction of τ+ = 122 and 73 ps and the H →π back reaction of τ- = 155 and 188 ps for PhOH(+)-Ar and PhOH(+)-Kr, respectively. The one order of magnitude slower time constant in comparison to the PhOH(+)-Ar2 trimer (τ+ = 7 ps) is attributed to the decrease in density of states due to the absence of the second Ar in the dimer. The similar time constants for both PhOH(+)-Rg dimers are well rationalized by a classical interpretation based on the comparable potential energy surfaces, reaction pathways, and density of states arising from their similar intermolecular vibrational frequencies.

  12. Picosecond lasers: the next generation of short-pulsed lasers.

    PubMed

    Freedman, Joshua R; Kaufman, Joely; Metelitsa, Andrea I; Green, Jeremy B

    2014-12-01

    Selective photothermolysis, first discussed in the context of targeted microsurgery in 1983, proposed that the optimal parameters for specific thermal damage rely critically on the duration over which energy is delivered to the tissue. At that time, nonspecific thermal damage had been an intrinsic limitation of all commercially available lasers, despite efforts to mitigate this by a variety of compensatory cooling mechanisms. Fifteen years later, experimental picosecond lasers were first reported in the dermatological literature to demonstrate greater efficacy over their nanosecond predecessors in the context of targeted destruction of tattoo ink. Within the last 4 years, more than a decade after those experiments, the first commercially available cutaneous picosecond laser unit became available (Cynosure, Westford, Massachusetts), and several pilot studies have demonstrated its utility in tattoo removal. An experimental picosecond infrared laser has also recently demonstrated a nonthermal tissue ablative capability in soft tissue, bone, and dentin. In this article, we review the published data pertaining to dermatology on picosecond lasers from their initial reports to the present as well as discuss forthcoming technology.

  13. Picosecond near-infrared excited transient Raman spectra of β-carotene in the excited S 2 state: Solvent effects on the in-phase C dbnd C stretching band and vibronic coupling

    NASA Astrophysics Data System (ADS)

    Sakamoto, Akira; Matsuno, Shinya; Tasumi, Mitsuo

    2010-07-01

    Picosecond time-resolved Raman spectra of β-carotene in the excited S 2 ( 1Bu+) state have been obtained in resonance with its near-infrared transient absorption. The Raman band due to the in-phase C dbnd C stretching mode of β-carotene in the S 2 state has been observed at about 1550 cm -1. The solvent effects on this band are discussed in comparison with the previous results on the corresponding bands in the ground S 0 ( 1Ag-) state and the excited S 1 ( 2Ag-) state.

  14. Picosecond and nanosecond studies of the photoreduction of benzophenone by N,N-diethylaniline and triethylamine

    SciTech Connect

    Devadoss, C.; Fessenden, R.W. )

    1991-09-19

    The photoreduction of benzophenone by N,N-diethylaniline and triethylamine has been examined in a number of solvents by both nano- and picosecond laser photolysis. With diethylaniline, electron transfer is the primary step and the spectrum of the ion pair has been detected even in nonpolar solvents such as benzene and cyclohexane. Rapid proton transfer then takes place to form a high yield of the ketyl radical. The lifetime of the ion pair in benzene is about 900 ps. In acetonitrile, the ion pair dissociated into individual ions which then decay by back electron transfer and proton transfer. A spectral shift to the red occurs over 100 ps as the contact ion pair dissociated. In acidic alcohols such as methanol and trifluoroethanol, proton transfer from the alcohol occurs to produce the ketyl radical. In the case of triethylamine, no distinct absorption band for benzophenone anion was seen in picosecond experiments but difference spectra, which removed much of the spectrum of benzophenone triplet, clearly showed some contribution from the anion. For this compound, it is likely that electron transfer occurs first followed by very fast proton transfer.

  15. Infrared sky noise study

    NASA Technical Reports Server (NTRS)

    Westphal, J. A.

    1972-01-01

    The hardware and techniques to measure and compare sky noise at several sites were studied, and a device was developed that would maximize its output and minimize its output for modulation. The instrument and its functions are described. The nature of sky emissions and the fluctuation, gaseous sources of sky noise, and aerosol sources are discussed. It is concluded that sky noise really exists, and the spatial distribution of the sky noise sources are such that observed noise values are linear functions of chopping stroke.

  16. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    SciTech Connect

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-07

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11–54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  17. Recrystallization of picosecond laser-melted ZnO nanoparticles in a liquid: a molecular dynamics study.

    PubMed

    Hu, Ming; Poulikakos, Dimos; Grigoropoulos, Costas P; Pan, Heng

    2010-04-28

    We employ molecular dynamics simulation to investigate the rapid melting and subsequent cooling process of zinc oxide (ZnO) nanoparticles in liquid tetradecane upon picosecond laser heating. The coalescence of two neighboring melted nanoparticles into a larger particle and the recrystallization of the latter upon cooling were studied. Severe undercooling and distinct recalescence occurs and the structure of the nanoparticle transforms from its initial hexagonal wurtzite structure to a face-centered cubic structure after recrystallization. By analyzing the heating/cooling process, we demonstrated that the particle size has a large impact on the interfacial thermal conductance between the nanoparticle and the surrounding liquid, as well as on the solidification initiation and solidification completion temperatures. We also investigated the thermal behavior of the surrounding liquid layer at the neighborhood of the particle surface. Boiling of the liquid layer was found in the case of extremely high heat fluxes.

  18. Recrystallization of picosecond laser-melted ZnO nanoparticles in a liquid: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Hu, Ming; Poulikakos, Dimos; Grigoropoulos, Costas P.; Pan, Heng

    2010-04-01

    We employ molecular dynamics simulation to investigate the rapid melting and subsequent cooling process of zinc oxide (ZnO) nanoparticles in liquid tetradecane upon picosecond laser heating. The coalescence of two neighboring melted nanoparticles into a larger particle and the recrystallization of the latter upon cooling were studied. Severe undercooling and distinct recalescence occurs and the structure of the nanoparticle transforms from its initial hexagonal wurtzite structure to a face-centered cubic structure after recrystallization. By analyzing the heating/cooling process, we demonstrated that the particle size has a large impact on the interfacial thermal conductance between the nanoparticle and the surrounding liquid, as well as on the solidification initiation and solidification completion temperatures. We also investigated the thermal behavior of the surrounding liquid layer at the neighborhood of the particle surface. Boiling of the liquid layer was found in the case of extremely high heat fluxes.

  19. Picosecond optoelectronic devices

    SciTech Connect

    Lee, C.L.

    1984-01-01

    Ever since the invention of picosecond lasers, scientists and electronic engineers have been dreaming of inventing electronic devices that can record in real time the physical and electronic events that take place on picosecond time scales. With the exception of the expensive streak camera, this dream has been largely unfullfilled. Today, a real-time oscilloscope with picosecond time resolution is still not available. To fill the need for even better time resolution, researchers have turned to optical pulses and thus a hybrid technology has emerged-picosecond optoelectronics. This technology, based on bulk photoconductors, has had a slow start. However, because of the simplicity, scaleability, and jitterfree nature of the devices, the technology has recently experienced a rapid growth. This volume reviews the major developments in the field of picosecond optoelectronics over the past decade.

  20. Picosecond spectroscopic studies of energy transfer in phycobiliproteins and model dye systems

    SciTech Connect

    Switalski, S.C.

    1987-02-01

    Energy transfer was investigated in the ..cap alpha beta.. monomer and separated ..cap alpha.. and ..beta.. subunits of C-phycocyanin from Anabaena variabilis and Anacystis nidulans, using steady-state and picosecond spectroscopy. Fluorescence excitation polarization spectra were consistent with a sensitizing (s) - fluorescing (f) model using a Forster energy transfer mechanism. The rise in polarization across the absorption band towards longer wavelength for the ..beta.. subunit and the ..cap alpha beta.. monomer was attributed to energy transfer among the three chromophores in the ..cap alpha beta.. monomer and between the 2 chromophores in the ..beta.. subunit. The constant polarization of the ..cap alpha.. subunit, with one chromophore, is consistent with a lack of any possibility of energy transfer. Fluorescence emission maxima were at 640 nm for the ..cap alpha beta.. monomer and the separated subunits of Anabaena variabilis, and 645 nm for the ..beta.. subunit, 640 nm for the ..cap alpha.. subunit, and 644 nm for ..cap alpha beta.. monomer of Anacystis nidulans. We have shown that the labels s and f are not consistent with all the steady-state spectroscopic results. 171 refs., 32 figs., 15 tabs.

  1. Time-dependent radiolytic yield of OH• radical studied by picosecond pulse radiolysis.

    PubMed

    El Omar, Abdel Karim; Schmidhammer, Uli; Jeunesse, Pierre; Larbre, Jean-Philippe; Lin, Mingzhang; Muroya, Yusa; Katsumura, Yosuke; Pernot, Pascal; Mostafavi, Mehran

    2011-11-10

    Picosecond pulse radiolysis measurements using a pulse-probe method are performed to measure directly the time-dependent radiolytic yield of the OH(•) radical in pure water. The time-dependent absorbance of OH(•) radical at 263 nm is deduced from the observed signal by subtracting the contribution of the hydrated electron and that of the irradiated empty fused silica cell which presents also a transient absoption. The time-dependent radiolytic yield of OH(•) is obtained by assuming the yield of the hydrated electron at 20 ps equal to 4.2 × 10(-7) mol J(-1) and by assuming the values of the extinction coefficients of e(aq)(-) and OH(•) at 782 nm (ε(λ=782 nm) = 17025 M(-1) cm(-1)) and at 263 nm (ε(λ=263 nm) = 460 M(-1) cm(-1)), respectively. The value of the yield of OH(•) radical at 10 ps is found to be (4.80 ± 0.12) × 10(-7) mol J(-1). PMID:21970432

  2. Photochemistry of (η6-anisole)Cr(CO)3 and (η6-thioanisole)Cr(CO)3: evidence for a photoinduced haptotropic shift of the thioanisole ligand, a picosecond time-resolved infrared spectroscopy and density functional theory investigation.

    PubMed

    Clark, Ian P; George, Michael W; Greetham, Gregory M; Harvey, Emma C; Long, Conor; Manton, Jennifer C; McArdle, Hazel; Pryce, Mary T

    2012-01-26

    The photochemistry of (η(6)-anisole)Cr(CO)(3) and (η(6)-thioanisole)Cr(CO)(3) was investigated by picosecond time-resolved infrared spectroscopy in n-heptane solution at 298 K. Two independent excited states are populated following 400 nm excitation of each of these complexes. An excited state with some metal-to-CO charge-transfer character is responsible for the CO-loss process, which is slow compared to CO-loss from Cr(CO)(6). Observed first order rate constants of 1.8 × 10(10) s(-1) and 2.5 × 10(10) s(-1) were obtained for the anisole and thioanisole complexes, respectively. The second excited state has metal-to-arene charge transfer character and results in a haptotropic shift of the thioanisole ligand. DFT calculations characterized the excited states involved and the nature of the haptotropic shift intermediate observed for the thioanisole species.

  3. Picosecond Resonance Raman Spectroscopy of Visual Pigments.

    NASA Astrophysics Data System (ADS)

    Carlsen, William Frederick

    We have constructed a picosecond Raman spectrometer to obtain information about primary events in visual excitation. The excitation source at 532 nm is a frequency doubled modelocked Nd:YAG laser optimized for short pulses, high repetition rates, and high pulse to pulse stability. The sample illumination geometry is optimized for pulsed Raman measurements using low magnification light collection and optical multi-channel detection. This instrument gives high signal to noise ratios and high data rates. The visual pigment rhodopsin was studied with this picosecond Raman instrument. We found that within 20 picoseconds of absorbing a photon, low wavenumber Raman bands characteristic of the first photo-intermediate bathorhodopsin appear. This scattering at 853, 875, and 920 wavenumbers arises from enhanced hydrogen out of plane vibrations from a strained all-trans configuration of the retinal chromophore in the protein. Furthermore, bands characteristic of isorhodopsin appear within the 10 picosecond pulse. We therefore conclude that the 11-cis retinal chromophore of rhodopsin isomerizes to a strained all-trans configuration and can further isomerize to a 9-cis form on absorbing a second photon, all within 20 picoseconds. Measurements starting with isorhodopsin show that the reverse process, 9-cis to trans to 11-cis, can also occur within 20 picoseconds. The resonance Raman spectra of bathorhodopsin formed from rhodopsin, however, exhibits consistent small differences from that of bathorhodopsin formed from isorhodopsin. Spectra of corresponding pigments deuterated at the retinal 12 carbon position also show slight differences. These data suggest that the bathorhodopsins formed from rhodopsin and isorhodopsin are initially different. They appear, however, to converge to a common intermediate by the end of 20 picoseconds. This resonance Raman study reveals that much of the isomerization of retinal takes place within a few picoseconds of the absorption of a photon by

  4. Observation of the picosecond supercontinuum

    NASA Astrophysics Data System (ADS)

    Siffalovic, Peter; Bugar, Ignac; Vojtek, Pavel

    1999-07-01

    Properties of the picosecond supercontinuum generated from water have been studied. We have shown development of a stimulated Raman scattering cross-phase modulation spectrum at the anti-Stokes side of the pump frequency. Supercontinuum diffraction patterns have been recorded and diffraction angles for several wavelengths have been measured. Requirement of the supercontinuum generation power threshold have been found out for different outputs. We have also analyzed defocusing interaction among pulses of the pump train.

  5. Photochemistry of (η(6)-arene)Cr(CO)3 (arene = methylbenzoate, naphthalene, or phenanthrene) in n-heptane solution: population of two excited states following 400 nm excitation as detected by picosecond time-resolved infrared spectroscopy.

    PubMed

    Clark, Ian P; George, Michael W; Greetham, Gregory M; Harvey, Emma C; Long, Conor; Manton, Jennifer C; Pryce, Mary T

    2011-04-14

    The photochemistry of (η(6)-methylbenzoate)Cr(CO)(3), (η(6)-naphthalene)Cr(CO)(3), and (η(6)-phenanthrene)Cr(CO)(3) in n-heptane solution was investigated by picosecond time-resolved infrared spectroscopy (TRIR). The observation of two transient IR features in the organic carbonyl region at 1681 and 1724 cm(-1) following 400 nm excitation of (η(6)-methylbenzoate)Cr(CO)(3) confirms formation of two excited states which are classified as metal-to-arene charge transfer (MACT) and metal-to-CO charge transfer (MCCT), respectively. Time-dependent density functional theory calculations have been used to support these assignments. Population of the MCCT excited state results in a slow (150 ps) expulsion of one CO ligand. Excitation of (η(6)-naphthalene)Cr(CO)(3) or (η(6)-phenanthrene)Cr(CO)(3) at either 400 or 345 nm produced two excited states: the MCCT state results in CO loss, while the MACT excited state results in a change to the coordination mode of the polyaromatic ligands before relaxing to the parent complex. A comparison of the infrared absorptions observed following the population of the MACT excited state with those calculated for nonplanar polyaromatic intermediates provides a model for the reduced hapticity species.

  6. Laser-driven phase transitions in aqueous colloidal gold nanoparticles under high pressure: picosecond pump-probe study.

    PubMed

    Hashimoto, Shuichi; Katayama, Tetsuro; Setoura, Kenji; Strasser, Michael; Uwada, Takayuki; Miyasaka, Hiroshi

    2016-02-14

    Pump-probe transient extinction spectroscopy was used to analyze 355 nm picosecond laser heating-induced phenomena in 60 nm-diameter aqueous gold nanoparticles (AuNPs) under a high pressure of 60 MPa. Kinetic spectroscopy revealed that a supercritical layer surrounding the AuNP nucleated with a lifetime of approximately 1 ns during its dynamic expansion and decay for a fluence of 19.6 mJ cm(-2). Moreover, in the post-mortem transmission electron micrographs we observed a number of fragments, a small percentage of size-reduced cores, and erupted particles among the intact particles after 60 shots, suggesting that evaporation occurred under laser illumination. The particle temperature calculation indicated that evaporation begins with a liquid droplet AuNP surrounded by a supercritical layer at temperatures below the boiling point of gold. By applying high pressure, we obtained a clear picture of the evaporation event, which was not possible at ambient pressure because bubble formation caused particle temperatures to rise uncontrollably. In this study, we shed light on the critical role of the supercritical layer formed around the AuNP under high pressure during laser-induced evaporation. PMID:26812175

  7. Broadly tunable picosecond ir source

    DOEpatents

    Campillo, A.J.; Hyer, R.C.; Shapiro, S.L.

    1980-04-23

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 ..mu..m picosecond pulses (1) pass through a 4.5 cm long LiNbO/sub 3/ optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO/sub 3/ optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 ..mu..m along both pump lines are 6 to 8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 ..mu..m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 ..mu..J of tunable radiation over the 14.8 to 18.5 ..mu..m region. The bandwidth and wavelength of both the 2 and 16 ..mu..m radiation output are controlled solely by the diffraction grating.

  8. Broadly tunable picosecond IR source

    DOEpatents

    Campillo, Anthony J.; Hyer, Ronald C.; Shapiro, Stanley J.

    1982-01-01

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 .mu.m picosecond pulses (1) pass through a 4.5 cm long LiNbO.sub.3 optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO.sub.3 optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 .mu.m along both pump lines are 6-8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 .mu.m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 .mu.J of tunable radiation over the 14.8 to 18.5 .mu.m region. The bandwidth and wavelength of both the 2 and 16 .mu.m radiation output are controlled solely by the diffraction grating.

  9. [Surfaces and thin films studied by picosecond ultrasonics]. Annual progress report, [December 1, 1993--November 30, 1994

    SciTech Connect

    Maris, H.J.

    1994-10-01

    We are using picosecond optics techniques to perform ultrasonic and thermal transport measurements on thin films and nanostructures. We are investigating the basic physics of sound and phonon propagation in solids, and also attempting to develop practical techniques for the ultrasonic evaluation of thin-film nanostructures.

  10. A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

    NASA Astrophysics Data System (ADS)

    Mangote, B.; Gallais, L.; Zerrad, M.; Lemarchand, F.; Gao, L. H.; Commandré, M.; Lequime, M.

    2012-01-01

    A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al2O3, Nb2O5, HfO2, SiO2, Ta2O5, and ZrO2. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

  11. A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

    SciTech Connect

    Mangote, B.; Gallais, L.; Zerrad, M.; Lemarchand, F.; Gao, L. H.; Commandre, M.; Lequime, M.

    2012-01-15

    A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al{sub 2}O{sub 3}, Nb{sub 2}O{sub 5}, HfO{sub 2}, SiO{sub 2}, Ta{sub 2}O{sub 5}, and ZrO{sub 2}. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

  12. Picosecond beam monitor

    DOEpatents

    Schutt, D.W.; Beck, G.O.

    1974-01-01

    The current in the beam of a particle accelerator is monitored with picosecond resolution by causing the beam to impinge upon the center conductor of a coaxial line, generating a pulse of electromagnetic energy in response thereto. This pulse is detected by means such as a sampling oscilloscope. (Official Gazette)

  13. Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

    SciTech Connect

    Hamad, Syed; Nageswara Rao, S. V. S.; Pathak, A. P.; Krishna Podagatlapalli, G.; Mounika, R.; Venugopal Rao, S. E-mail: soma-venu@uohyd.ac.in

    2015-12-15

    We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO{sub 2} NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (<1 ps) and non-radiative transitions (>1 ps). Large third order optical nonlinearities (∼10{sup −14} e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm

  14. Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Hamad, Syed; Krishna Podagatlapalli, G.; Mounika, R.; Nageswara Rao, S. V. S.; Pathak, A. P.; Venugopal Rao, S.

    2015-12-01

    We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ˜2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ˜9.5 nm, ˜37 nm, ˜45 nm and ˜42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO2 NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ˜150 fs (100 MHz) and ˜70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (<1 ps) and non-radiative transitions (>1 ps). Large third order optical nonlinearities (˜10-14 e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm suggesting that the

  15. CO photodissociation dynamics in cytochrome P450BM3 studied by subpicosecond visible and mid-infrared spectroscopy.

    PubMed

    Rupenyan, Alisa; Commandeur, Jan; Groot, Marie Louise

    2009-07-01

    Cytochrome P450BM3 is a bacterial enzyme with a heme cofactor that binds small diatomic ligands. Here we report the first study of carbon monoxide (CO) photodissociation and rebinding in ferrous P450BM3 on an ultrafast time scale. We monitored dissociation of carbon monoxide upon Soret band excitation using visible and infrared femtosecond spectroscopy between 100 fs and 4 ns. The dynamics of the ferric P450 was probed for reference in the visible spectral region. In the photodissociated ferrous P450-CO complex, the vibrational hot deligated ground state is populated in 0.2 ps and relaxes on a picosecond time scale. The onset of geminate recombination of CO with the heme is observed on a nanosecond time scale. In the mid-infrared spectral region, the bleached absorption due to the bound C=O stretch vibration is constant on the picosecond to 1 ns time scale, indicating that the photodissociation yield is 100% and that rebinding occurs after 1 ns. In the infrared absorption difference spectra, we additionally resolve two small bands of dissociated CO molecules at 2092 and 2114 cm(-1). This indicates that the escape of photolyzed CO to solvent and the geminate recombination are preceded by transient docking within the protein in a manner similar to that of globins. The bands partially decay with a time constant of 1 ps, possibly due to a relaxation of the protein around the CO docking site, allowing for greater orientational freedom of the CO molecules.

  16. Ab Initio Study of Hot Carriers in the First Picosecond after Sunlight Absorption in Silicon

    NASA Astrophysics Data System (ADS)

    Bernardi, Marco; Vigil-Fowler, Derek; Lischner, Johannes; Neaton, Jeffrey B.; Louie, Steven G.

    2014-06-01

    Hot carrier thermalization is a major source of efficiency loss in solar cells. Because of the subpicosecond time scale and complex physics involved, a microscopic characterization of hot carriers is challenging even for the simplest materials. We develop and apply an ab initio approach based on density functional theory and many-body perturbation theory to investigate hot carriers in semiconductors. Our calculations include electron-electron and electron-phonon interactions, and require no experimental input other than the structure of the material. We apply our approach to study the relaxation time and mean free path of hot carriers in Si, and map the band and k dependence of these quantities. We demonstrate that a hot carrier distribution characteristic of Si under solar illumination thermalizes within 350 fs, in excellent agreement with pump-probe experiments. Our work sheds light on the subpicosecond time scale after sunlight absorption in Si, and constitutes a first step towards ab initio quantification of hot carrier dynamics in materials.

  17. Picosecond Spin Caloritronics

    NASA Astrophysics Data System (ADS)

    Cahill, David G.

    The coupling of spin and heat, i.e., spin caloritronics, gives rise to new physical phenomena in nanoscale spin devices and new ways to manipulate local magnetization. Our work in this field takes advantage of recent advances in the measurement and understanding of heat transport at the nanoscale using ultrafast lasers. We use a picosecond duration pump laser pulses as a source of heat and picosecond duration probe laser pulses to detect changes in temperature, spin accumulation, and spin transfer torque using a combination of time-domain thermoreflectance and time-resolved magneto-optic Kerr effect Our pump-probe optical methods enable us to change the temperature of ferromagnetic layers on a picosecond time-scale and generate enormous heat fluxes on the order of 100 GW m-2 that persist for ~ 30 ps. Thermally-driven ultrafast demagnetization of a perpendicular ferromagnet leads to spin accumulation in a normal metal and spin transfer torque in an in-plane ferromagnet. The data are well described by models of spin generation and transport based on differences and gradients of thermodynamic parameters. The spin-dependent Seebeck effect of a perpendicular ferromagnetic layer converts a heat current into spin current, which in turn can be used to exert a spin transfer torque (STT) on a second ferromagnetic layer with in-plane magnetization. Using a [Co,Ni] multilayer as the source of spin, an energy fluence of ~ 4 J m-2 creates thermal STT sufficient to induce ~ 1 % tilting of the magnetization of a 2 nm-thick CoFeB layer.

  18. OSA proceedings on picosecond electronics and optoelectronics

    SciTech Connect

    Sollner, T.C.L.G. . Lincoln Lab.); Bloom, D.M. . Edward L. Ginzton Lab.)

    1989-01-01

    This book presents an introduction to optical communications. Systems considerations of this important application of optoelectronics are used to provide the motivation for many of the papers that follow. The authors are also concerned with another optoelectronic application, the measurement of phenomena that take place on a picosecond time scale. Short optical or electrical pulses are used to sample the parameter of interest, usually electric fields, in electronic or optoelectronic devices and circuits. Several methods of sampling are described, as are improvements to components that make up these systems. The authors address the electronic and optoelectronic components that lay the foundation for the systems considered above. Diode laser chirping, picosecond optical pulse amplifiers, a spread-spectrum approach to modulation, and two novel methods of picosecond pulse synthesis are discussed. Papers on tunneling and resonant tunneling are presented. Devices based on these effects have promise in high-speed electronics. Several papers investigate the speed of electron tunneling between two reservoirs and the effect of speed on device performance. Resonant-tunneling diode switches are also considered. This book also covers transistors as well as studies of carrier transport on the picosecond time scale. Excellent results for silicon FETs are given, demonstrating the great flexibility of that established technology.

  19. Picosecond absorption relaxation measured with nanosecond laser photoacoustics

    NASA Astrophysics Data System (ADS)

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2010-10-01

    Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural—including strongly scattering and nonfluorescent—materials.

  20. An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for ``double kinetics'' experiments: Application to fluorescence resonance excitation energy transfer study of protein folding

    NASA Astrophysics Data System (ADS)

    Ishay, Eldad Ben; Hazan, Gershon; Rahamim, Gil; Amir, Dan; Haas, Elisha

    2012-08-01

    The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals. Here, we report the development of an instrument, picosecond double kinetics apparatus, that enables recording of multiple fluorescence decay curves with picosecond excitation pulses over wide spectral range during microsecond data collection for each curve. The design is based on recording and averaging multiphoton pulses of fluorescence decay using a fast 13 GHz oscilloscope during microsecond time intervals at selected time points over the course of a chemical reaction or conformational transition. We tested this instrument in a double kinetics experiment using reference probes (N-acetyl-tryptophanamide). Very low stochastic noise level was attained, and reliable multi-parameter analysis such as derivation of distance distributions from time resolved FRET (fluorescence resonance excitation energy transfer) measurements was achieved. The advantage of the pulse recording and averaging approach used here relative to double kinetics methods based on the established time correlated single photon counting method, is that in the pulse recording approach, averaging of substantially fewer kinetic experiments is sufficient for obtaining the data. This results in a major reduction in the consumption of labeled samples, which in many cases, enables the performance of important experiments that were not previously feasible.

  1. Mariner Jupiter/Saturn infrared instrument study

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The Mariner Jupiter/Saturn infrared instrumentation conceptual design study was conducted to determine the physical and operational characteristics of the instruments needed to satisfy the experiment science requirements. The design of the instruments is based on using as many proven concepts as possible. Many design features are taken from current developments such as the Mariner, Pioneer 10, Viking Orbiter radiometers, and Nimbus D spectrometer. Calibration techniques and error analysis for the instrument system are discussed.

  2. Picosecond laser filamentation in air

    NASA Astrophysics Data System (ADS)

    Schmitt-Sody, Andreas; Kurz, Heiko G.; Bergé, Luc; Skupin, Stefan; Polynkin, Pavel

    2016-09-01

    The propagation of intense picosecond laser pulses in air in the presence of strong nonlinear self-action effects and air ionization is investigated experimentally and numerically. The model used for numerical analysis is based on the nonlinear propagator for the optical field coupled to the rate equations for the production of various ionic species and plasma temperature. Our results show that the phenomenon of plasma-driven intensity clamping, which has been paramount in femtosecond laser filamentation, holds for picosecond pulses. Furthermore, the temporal pulse distortions in the picosecond regime are limited and the pulse fluence is also clamped. In focused propagation geometry, a unique feature of picosecond filamentation is the production of a broad, fully ionized air channel, continuous both longitudinally and transversely, which may be instrumental for many applications including laser-guided electrical breakdown of air, channeling microwave beams and air lasing.

  3. [Study on photographing experiment of infrared detector].

    PubMed

    Wang, De-Jiang; Zhang, Tao

    2011-01-01

    Infrared detectors are widely used in multi spectral remote sensing systems, and in order to verify photographing principles of infrared time delay integration (TDI) detector, and make preparations for future research, a verification system for infrared TDI camera is proposed in the present paper. Experimental methods are explained thoroughly and two major factors which affect image quality are analyzed. First, the causes of image motion and their effects on the quality of image are studied, and a novel architecture using high precision DC-speed machine is presented, then the relationship between velocity of precision turntable and detectors line transfer frequency is determined by Kalman algorithm. Second, four focusing means are analyzed and compared, and video signal amplitude method is selected according to practical application. Finally, a genuine demo system is established in national supervision and test center for optics mechanics quality. 5.3, 6.4 and 9.2 mm drones are chosen for testing. Experimental results indicate that the obtained drone is vivid, and camera's resolution achieves 11.3 lines per mm, which satisfies preliminary aims.

  4. Picosecond x-ray measurements from 100 eV to 30 keV

    SciTech Connect

    Attwood, D.T.; Kauffman, R.L.; Stradling, G.L.

    1980-10-15

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices.

  5. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.

    1993-03-01

    The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.

  6. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    underlying physics. There are now at least six different disciplines that deal with infrared radiation in one form or another, and in one or several different spectral portions of the whole IR range. These are spectroscopy, astronomy, thermal imaging, detector and source development and metrology, as well the field of optical data transmission. Scientists working in these fields range from chemists and astronomers through to physicists and even photographers. This issue presents examples from some of these fields. All the papers—though some of them deal with fundamental or applied research—include interesting elements that make them directly applicable to university-level teaching at the graduate or postgraduate level. Source (e.g. quantum cascade lasers) and detector development (e.g. multispectral sensors), as well as metrology issues and optical data transmission, are omitted since they belong to fundamental research journals. Using a more-or-less arbitrary order according to wavelength range, the issue starts with a paper on the physics of near-infrared photography using consumer product cameras in the spectral range from 800 nm to 1.1 µm [1]. It is followed by a series of three papers dealing with IR imaging in spectral ranges from 3 to 14 µm [2-4]. One of them deals with laboratory courses that may help to characterize the IR camera response [2], the second discusses potential applications for nondestructive testing techniques [3] and the third gives an example of how IR thermal imaging may be used to understand cloud cover of the Earth [4], which is the prerequisite for successful climate modelling. The next two papers cover the vast field of IR spectroscopy [5, 6]. The first of these deals with Fourier transform infrared spectroscopy in the spectral range from 2.5 to 25 µm, studying e.g. ro-vibrational excitations in gases or optical phonon interactions within solids [5]. The second deals mostly with the spectroscopy of liquids such as biofuels and special

  7. Picosecond time-resolved emission studies. I. Real-time measurements of solvent-solute interactions. II. Kinetics of energy flow in a photosynthetic antenna system. [4-aminophthalimide

    SciTech Connect

    Yeh, S.W.

    1985-11-01

    Using a picosecond fluorimeter, the dynamics of solvation of electronically excited 4-aminophthalimide in a variety of solvents is measured. The solvation process is manifested by a time-dependent red shift in the emission spectrum in certain solvents. This red shift is time-resolved using a streak camera system. The time constant of the relaxation is found to correlate strongly with the longitudinal dielectric relaxation rate of the solvent. The correlation holds for changes in solvent, for isotopic substitution of a solvent, and for changes in temperature. Never before have direct measurements of excited-state solvation dynamics been shown to correlate with dielectric relaxation over such a wide range of experimental conditions. Emission from certain photosynthetic antenna complexes, phycobilisomes, and from the building blocks of phycobilisomes, phycobiliproteins, has also been studied using the streak camera system. Both the rising and filling portions of the time-resolved emission profiles of the fluorescing chromophores in these structures are studied. The rates of energy transfer between structural domains of the antenna complex and within the isolated biliprotein complexes are deduced from these studies. Comparison of emission profiles from a series of structurally distinct phycobilisomes isolated from three related strains of cyanobacteria have provided new insights into the correlation of the energy transfer function and macromolecular structure in these light-harvesting antenna systems. 133 refs., 58 figs., 14 tabs.

  8. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    underlying physics. There are now at least six different disciplines that deal with infrared radiation in one form or another, and in one or several different spectral portions of the whole IR range. These are spectroscopy, astronomy, thermal imaging, detector and source development and metrology, as well the field of optical data transmission. Scientists working in these fields range from chemists and astronomers through to physicists and even photographers. This issue presents examples from some of these fields. All the papers—though some of them deal with fundamental or applied research—include interesting elements that make them directly applicable to university-level teaching at the graduate or postgraduate level. Source (e.g. quantum cascade lasers) and detector development (e.g. multispectral sensors), as well as metrology issues and optical data transmission, are omitted since they belong to fundamental research journals. Using a more-or-less arbitrary order according to wavelength range, the issue starts with a paper on the physics of near-infrared photography using consumer product cameras in the spectral range from 800 nm to 1.1 µm [1]. It is followed by a series of three papers dealing with IR imaging in spectral ranges from 3 to 14 µm [2-4]. One of them deals with laboratory courses that may help to characterize the IR camera response [2], the second discusses potential applications for nondestructive testing techniques [3] and the third gives an example of how IR thermal imaging may be used to understand cloud cover of the Earth [4], which is the prerequisite for successful climate modelling. The next two papers cover the vast field of IR spectroscopy [5, 6]. The first of these deals with Fourier transform infrared spectroscopy in the spectral range from 2.5 to 25 µm, studying e.g. ro-vibrational excitations in gases or optical phonon interactions within solids [5]. The second deals mostly with the spectroscopy of liquids such as biofuels and special

  9. New format presentation for infrared spectral emittance data. Infrared spectrometry studies, phase 5

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.; Green, A. A.

    1972-01-01

    Methods for infrared radiance measurements from geological materials were studied for airborne use over terrains with minimal vegetation. The tasks of the investigation were: (1) calculation of emittance ratios, (2) comparison of IR spectral emittance data with K-band scatterometer data over Pisgah Crater, and (3) standard infrared spectral file. Published papers reporting the research are included.

  10. High brightness picosecond electron gun

    SciTech Connect

    Merano, M.; Collin, S.; Renucci, P.; Gatri, M.; Sonderegger, S.; Crottini, A.; Ganiere, J.D.; Deveaud, B.

    2005-08-15

    We have developed a high brightness picosecond electron gun. We have used it to replace the thermionic electron gun of a commercial scanning electron microscope (SEM) in order to perform time-resolved cathodoluminescence experiments. Picosecond electron pulses are produced, at a repetition rate of 80.7 MHz, by femtosecond mode-locked laser pulses focused on a metal photocathode. This system has a normalized axial brightness of 93 A/cm{sup 2} sr kV, allowing for a spatial resolution of 50 nm in the secondary electron imaging mode of the SEM. The temporal width of the electron pulse is 12 ps.

  11. Study on vibrational relaxation dynamics of phenol-water complex by picosecond time-resolved IR-UV pump-probe spectroscopy in a supersonic molecular beam

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yasunori; Inokuchi, Yoshiya; Ebata, Takayuki; Petković, Milena

    2013-06-01

    A comparative study of vibrational energy relaxation (VER) between the monohydrated complexes of phenol-d0 and phenol-d1 is investigated in a supersonic molecular beam. The direct time-resolved measurement of energy redistribution from the phenolic OH/OD stretching mode of the phenol-d0-H2O/phenol-d1-D2O is performed by picosecond IR-UV pump-probe spectroscopy. Two complexes follow the same relaxation process that begins with the intramolecular vibrational energy redistribution (IVR) and the intermolecular vibrational energy redistribution (IVR), which is followed by the vibrational predissociation (VP). The difference in the relaxation lifetimes between them is discussed by anharmonic force field and RRKM calculations. Anharmonic analysis implies that intra- (IVR) and intermolecular (IVR) relaxations occur in parallel in the complexes. The RRKM-predicted dissociation (VP) lifetimes show qualitative agreement with the observed results, suggesting that VP takes place after the statistical energy distribution in the complexes.

  12. Infrared Imaging System for Studying Brain Function

    NASA Technical Reports Server (NTRS)

    Mintz, Frederick; Mintz, Frederick; Gunapala, Sarath

    2007-01-01

    A proposed special-purpose infrared imaging system would be a compact, portable, less-expensive alternative to functional magnetic resonance imaging (fMRI) systems heretofore used to study brain function. Whereas a typical fMRI system fills a large room, and must be magnetically isolated, this system would fit into a bicycle helmet. The system would include an assembly that would be mounted inside the padding in a modified bicycle helmet or other suitable headgear. The assembly would include newly designed infrared photodetectors and data-acquisition circuits on integrated-circuit chips on low-thermal-conductivity supports in evacuated housings (see figure) arranged in multiple rows and columns that would define image coordinates. Each housing would be spring-loaded against the wearer s head. The chips would be cooled by a small Stirling Engine mounted contiguous to, but thermally isolated from, the portions of the assembly in thermal contact with the wearer s head. Flexible wires or cables for transmitting data from the aforementioned chips would be routed to an integrated, multichannel transmitter and thence through the top of the assembly to a patch antenna on the outside of the helmet. The multiple streams of data from the infrared-detector chips would be sent to a remote site, where they would be processed, by software, into a three-dimensional display of evoked potentials that would represent firing neuronal bundles and thereby indicate locations of neuronal activity associated with mental or physical activity. The 3D images will be analogous to current fMRI images. The data would also be made available, in real-time, for comparison with data in local or internationally accessible relational databases that already exist in universities and research centers. Hence, this system could be used in research on, and for the diagnosis of response from the wearer s brain to physiological, psychological, and environmental changes in real time. The images would also be

  13. Infrared laboratory studies of synthetic planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Williams, D.

    1973-01-01

    Previous research dealing with telluric gases is briefly reviewed. Current research concerning absorption-line broadening, and particulate constituents of planetary atmospheres are discussed. Two articles are included: optical constants of liquid ammonia in the infrared, and broadening of infrared absorption lines at reduced temperatures for nitrous oxide.

  14. Optothermal response of plasmonic nanofocusing lens under picosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Du, Z.; Chen, C.; Traverso, L.; Xu, X.; Pan, L.; Chao, I.-H.; Lavine, A. S.

    2014-03-01

    This work studied the optothermal response of plasmonic nanofocusing structures under picosecond pulsed laser irradiation. The surface plasmon polariton is simulated to calculate the optical energy dissipation as the Joule heating source and the thermal transport process is studied using a two temperature model (TTM). At the picosecond time scale that we are interested in, the Fourier heat equation is used to study the electron thermal transport and the hyperbolic heat equation is used to study the lattice thermal transport. For comparison, the single temperature model (STM) is also studied. The difference between TTM and STM indicates that TTM provides more accurate estimates in the picosecond time scale and the STM results are only reliable when the local electron and lattice temperature difference is negligible.

  15. [The study of transpiration influence on plant infrared radiation character].

    PubMed

    Ling, Jun; Zhang, Shuan-Qin; Pan, Jia-Liang; Lian, Chang-Chun; Yang, Hui

    2012-07-01

    Studying vegetation infrared radiation character is the base of developing infrared camouflage and concealment technology of ground military target. Accurate fusion of target and background can be achieved by simulating formation mechanism of vegetation infrared radiation character. Leaf transpiration is characteristic physiological mechanism of vegetation and one of the main factors that influence its infrared radiation character. In the present paper, physical model of leaf energy balance is set up. Based on this model the influence of plant transpiration on leaf temperature is analyzed and calculated. The daily periodic variation of transpiration, leaf temperature and infrared radiation character of typical plants such as camphor tree and holly is actually measured with porometer and infrared thermal imaging system. By contrasting plant leaf with dryness leaf, experimental data indicates that plant transpiration can regulate leaf energy balance effectively and control leaf temperature in a reasonable range and suppress deep range variation of leaf infrared radiation character.

  16. Preparation of water soluble L-arginine capped CdSe/ZnS QDs and their interaction with synthetic DNA: Picosecond-resolved FRET study

    SciTech Connect

    Giri, Anupam; Goswami, Nirmal; Lemmens, Peter; Pal, Samir Kumar

    2012-08-15

    Graphical abstract: Förster resonance energy transfer (FRET) studies on the interaction of water soluble arginine-capped CdSe/ZnS QDs with ethidium bromide (EB) labeled synthetic dodecamer DNA. Highlights: ► We have solubilized CdSe/ZnS QD in water replacing their TOPO ligand by L-arginine. ► We have studied arginine@QD–DNA interaction using FRET technique. ► Arginine@QDs act as energy donor and ethidium bromide-DNA acts as energy acceptor. ► We have applied a kinetic model to understand the kinetics of energy transfer. ► Circular dichroism studies revealed negligible perturbation in the DNA B-form in the arg@QD-DNA complex. -- Abstract: We have exchanged TOPO (trioctylphosphine oxide) ligand of CdSe/ZnS core/shell quantum dots (QDs) with an amino acid L-arginine (Arg) at the toluene/water interface and eventually rendered the QDs from toluene to aqueous phase. We have studied the interaction of the water soluble Arg-capped QDs (energy donor) with ethidium (EB) labeled synthetic dodecamer DNA (energy acceptor) using picoseconds resolved Förster resonance energy transfer (FRET) technique. Furthermore, we have applied a model developed by M. Tachiya to understand the kinetics of energy transfer and the distribution of acceptor (EB-DNA) molecules around the donor QDs. Circular dichroism (CD) studies revealed a negligible perturbation in the native B-form structure of the DNA upon interaction with Arg-capped QDs. The melting and the rehybridization pathways of the DNA attached to the QDs have been monitored by the CD which reveals hydrogen bonding is the associative mechanism for interaction between Arg-capped QDs and DNA.

  17. Raman and infrared spectroscopic study of turquoise minerals.

    PubMed

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed. PMID:25956330

  18. Raman and infrared spectroscopic study of turquoise minerals

    NASA Astrophysics Data System (ADS)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  19. Raman and infrared spectroscopic study of turquoise minerals.

    PubMed

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed.

  20. Spectrum of synchronous picosecond sonoluminescence

    NASA Astrophysics Data System (ADS)

    Hiller, Robert; Putterman, Seth J.; Barber, Bradley P.

    1992-08-01

    The clocklike emission of picosecond pulses of light with a peak power over 30 mW has been observed to originate from a bubble trapped at the velocity node of a resonant sound field in water. The spectrum of this bright sonoluminescence is broadband and our measurements show that if a spectral peak exists, it lies at photon energies above 6 eV.

  1. The use of picosecond lasers beyond tattoos.

    PubMed

    Forbat, E; Al-Niaimi, F

    2016-10-01

    Picosecond lasers are a novel laser with the ability to create a pulse of less than one nanosecond. They have been available in the clinical context since 2012. Dermatologists are now using picosecond lasers regularly for the treatment of blue and green pigment tattoo removal. This article reviews the use of picosecond lasers beyond tattoo removal. The overall consensus for the use of picosecond lasers beyond tattoo treatment is positive. With examples of this in the treatment of nevus of Ota, minocycline-induced pigmentation, acne scarring, and rhytides.

  2. The use of picosecond lasers beyond tattoos.

    PubMed

    Forbat, E; Al-Niaimi, F

    2016-10-01

    Picosecond lasers are a novel laser with the ability to create a pulse of less than one nanosecond. They have been available in the clinical context since 2012. Dermatologists are now using picosecond lasers regularly for the treatment of blue and green pigment tattoo removal. This article reviews the use of picosecond lasers beyond tattoo removal. The overall consensus for the use of picosecond lasers beyond tattoo treatment is positive. With examples of this in the treatment of nevus of Ota, minocycline-induced pigmentation, acne scarring, and rhytides. PMID:27183360

  3. [Surfaces and thin films studied by picosecond ultrasonics]. Annual progress report, [December 1, 1992--November 30, 1993

    SciTech Connect

    Maris, H.J.; Tauc, J.

    1993-11-01

    The goal of this research is the study of the propagation of very high frequency sound waves in amorphous materials and liquids in order to achieve a better fundamental understanding of how heat flows in these materials.

  4. The effect of picosecond laser pulses on redox-dependent processes in mice red blood cells studied in vivo

    NASA Astrophysics Data System (ADS)

    Voronova, Olga; Gening, Tatyana; Abakumova, Tatyana; Sysolyatin, Aleksey; Zolotovskiy, Igor; Antoneeva, Inna; Ostatochnikov, Vladimir; Gening, Snezhanna

    2014-02-01

    The study highlights the effect of different modes of in vivo laser irradiation of mice using a PFL8LA laser with λ = 1560 nm, pulse duration of 1,4•10-12 s, peak power of 3,72•103 W and average output power of 20•10-3 W on the lipid peroxidation parameters: conjugated dienes, ketodienes and conjugated trienes, malondialdehyde, Schiff bases and the activity of antioxidant enzymes - catalase, glutathione -S-transferase and superoxide dismutase in erythrocytes and plasma of mice. Two groups of mice received a total dose of 3.8 J/cm2 per group, but the 1st group was irradiated only once, while the 2nd - four times. Significant differences in the parameters of the 1st and 2nd groups indicate different effects of the irradiation modes on redox-dependent processes in red blood cells of mice.

  5. Effect of room temperature surface active ionic liquids on aggregated nanostructures of γ-Cyclodextrins: A picosecond fluorescence spectroscopic study

    NASA Astrophysics Data System (ADS)

    Kuchlyan, Jagannath; Banerjee, Chiranjib; Ghosh, Surajit; Kundu, Niloy; Banik, Debasis; Sarkar, Nilmoni

    2014-05-01

    In this Letter we report on controllable transition of aggregated γ-Cyclodextrins (γ-CDs) nanostructures by tuning the concentration of a long chain ionic liquid, 1-dodecyl-3-methyl imidazolium chloride (C12mimCl) added to the aqueous solution of γ-CDs. The gradual increase in concentration of C12mimCl first results in the breaking of γ-CDs aggregates by the formation of inclusion complexes with C12mimCl and then self-organizes into a new supramolecular aggregate. This spontaneous transition from one nanostructure to another has been established by spectroscopic and microscopic studies. It is worth to mention that addition of 1-octyl-3-methyl imidazolium chloride (C8mimCl) does not lead to any such transition.

  6. Picosecond laser studies of V-T processes in gases and electronic excitation transport in disordered systems

    SciTech Connect

    Hedstrom, J.F.

    1987-06-01

    SVL fluorescence spectroscopy was used to study intramolecular energy transfer from the 0/sup 0/ level of aniline induced by collisions with CO/sub 2/. Time-correlated photon counting was used to measure concentration dependent fluorescence depolarization for rhodamine 6G in glycerol. Fluorescence decays from these viscous solutions provide data for analyzing the three-dimensional, three-body excitation transport theory developed by Gochanour, Andersen and Fayer for disordered systems. The two-dimensional, two-body excitation theory developed by Loring and Fayer was also examined using time-resolved fluorescence depolarization techniques. The samples, made up of submonolayers of rhodamine 3B adsorbed onto optically flat fused silica yield fluorescence profiles which agree well with profiles developed from the theory for reduced surface coverages up to approx.0.4. At higher coverages, excitation trapping by rhodamine 3B aggregates truncates the depolarization process, yielding apparent reduced coverages which are appreciably lower than the true coverages.

  7. Picosecond coherent anti-Stokes Raman scattering (CARS) study of vibrational dephasing of carbon disulfide and benzene in solution

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Woodward, Anne M.; Stephenson, John C.

    1986-01-01

    The vibrational dephasing of the 656/cm mode (nu1, a1g) of CS2 and the 991/cm mode (nu2, a1g) of benzene have been studied as a function of concentration in mixtures with a number of solvents using a ps time-resolved CARS technique. This technique employs two tunable synchronously-pumped mode-locked dye lasers in a stimulated Raman pump, coherent anti-Stokes Raman probe time-resolved experiment. Results are obtained for CS2 in carbon tetrachloride, benzene, nitrobenzene, and ethanol and for benzene nu2 in CS2. The dephasing rates of CS2 nu1 increase on dilution with the polar solvents and decrease or remain constant on dilution with the nonpolar solvents. The CS2/benzene solutions show a contrasting behavior, with the CS2 nu1 dephasing rate being nearly independent of concentration whereas the benzene nu2 dephasing rate decreases on dilution. These results are compared to theoretical models for vibrational dephasing of polyatomic molecules in solution.

  8. Infrared spectroscopy study of irradiated PVDF

    SciTech Connect

    Chappa, Veronica; Grosso, Mariela del; Garcia Bermudez, Gerardo; Behar, Moni

    2007-10-26

    The effects induced by 1 MeV/amu ion irradiations were compared to those induced by 4-12 MeV/amu irradiations. Structural analysis with infrared spectroscopy (FTIR) was carried out on PVDF irradiated using C and He beams with different fluences. From these spectra it was observed, as a function of fluence, an overall destruction of the polymer, amorphization of the crystalline regions and the creation of in-chain unsaturations. The track dimensions were determined using a previously developed Monte Carlo simulation code and these results were compared to a semiempirical model.

  9. Picosecond lasers for tattoo removal: a systematic review.

    PubMed

    Reiter, Ofer; Atzmony, Lihi; Akerman, Lehavit; Levi, Assi; Kershenovich, Ruben; Lapidoth, Moshe; Mimouni, Daniel

    2016-09-01

    Given that the pigment particles in tattoos have a relaxation time of <10 ns, picosecond lasers would be expected to be more effective than nanosecond lasers in tattoo removal. To systematically review the evidence regarding the effectiveness and safety of picosecond lasers for tattoo removal, Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and reference lists were searched for relevant trials. The primary outcome was >70 % clearance of tattoo pigment. Secondary outcomes were 90-100 % clearance of tattoo pigment, number of laser sessions required, and adverse effects. Eight trials were included, six with human participants (160 participants) and 2 with animal models. Seven of the eight trials explored the usage of either 755, 758, 795, 1064, or 1064/532-nm picosecond lasers for black and blue ink tattoos. In the human trials, 69-100 % of tattoos showed over 70 % clearance of pigment after 1-10 laser treatments. Reported side effects included pain, hyperpigmentation and hypopigmentation, blister formation and transient erythema, edema, and pinpoint bleeding. Included articles varied in type of laser investigated, mostly non-comparative studies and with a medium to high risk of bias. There is sparse evidence that picosecond lasers are more effective than their nanosecond counterparts for mainly black and blue ink tattoo removal, with minor side effects.

  10. Picosecond lasers for tattoo removal: a systematic review.

    PubMed

    Reiter, Ofer; Atzmony, Lihi; Akerman, Lehavit; Levi, Assi; Kershenovich, Ruben; Lapidoth, Moshe; Mimouni, Daniel

    2016-09-01

    Given that the pigment particles in tattoos have a relaxation time of <10 ns, picosecond lasers would be expected to be more effective than nanosecond lasers in tattoo removal. To systematically review the evidence regarding the effectiveness and safety of picosecond lasers for tattoo removal, Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and reference lists were searched for relevant trials. The primary outcome was >70 % clearance of tattoo pigment. Secondary outcomes were 90-100 % clearance of tattoo pigment, number of laser sessions required, and adverse effects. Eight trials were included, six with human participants (160 participants) and 2 with animal models. Seven of the eight trials explored the usage of either 755, 758, 795, 1064, or 1064/532-nm picosecond lasers for black and blue ink tattoos. In the human trials, 69-100 % of tattoos showed over 70 % clearance of pigment after 1-10 laser treatments. Reported side effects included pain, hyperpigmentation and hypopigmentation, blister formation and transient erythema, edema, and pinpoint bleeding. Included articles varied in type of laser investigated, mostly non-comparative studies and with a medium to high risk of bias. There is sparse evidence that picosecond lasers are more effective than their nanosecond counterparts for mainly black and blue ink tattoo removal, with minor side effects. PMID:27311768

  11. Case study: using infrared technology for evidentiary purposes

    NASA Astrophysics Data System (ADS)

    Jolivet, Noel D.; Hansen, Joel; Miller, John Lester; Beniga, Rico; Austria, Rich

    2014-06-01

    Infrared technology and imaging systems are already used extensively by the law enforcement (LE) community, typically to gain a tactical advantage or obtain immediate situational awareness. As the use of infrared technology becomes more affordable and widespread, LE is finding new ways to use it and leverage the results in the courtroom as evidence. A case study will be presented where infrared imagery was used to support the Portland Police Bureau (PPB) in prosecuting an individual for a crime where a conviction might not have been assured without said imagery. Tests conducted at FLIR Systems, combined with expert witness testimony by a FLIR employee, helped a jury understand the significance of a key piece of infrared evidence, resulting in a conviction of the criminal. This case was the first Federal case of its kind where infrared imagery was used forensically as evidence and, as such, established precedence. Prior to this, infrared imagery has been offered and debated in court only as to whether it constitutes a legal search. Courtroom observations and lessons learned from this trial have shown that both industry and LE can do a better job of making the prosecution's cases stronger utilizing infrared technology and thus taking criminals off the street.

  12. Simultaneous picosecond and femtosecond solitons delivered from a nanotube-mode-locked all-fiber laser.

    PubMed

    Han, D D; Liu, X M; Cui, Y D; Wang, G X; Zeng, C; Yun, L

    2014-03-15

    We propose a compact nanotube-mode-locked all-fiber laser that can simultaneously generate picosecond and femtosecond solitons at different wavelengths. The pulse durations of picosecond and femtosecond solitons are measured to be ∼10.6  ps and ∼466  fs, respectively. Numerical results agree well with the experimental observations and clearly reveal that the dynamic evolutions of the picosecond and femtosecond solitons are qualitatively distinct in the intracavity. Our study presents a simple, stable, low-cost, and dual-scale ultrafast-pulsed laser source suitable for practical applications in optical communications.

  13. Picosecond spectroscopic studies of equilibrium structural fluctuations of native and partially unfolded states of Zinc II-substituted and metal-free cytochromes C

    NASA Astrophysics Data System (ADS)

    Tripathy, Jagnyaseni

    Picosecond time-resolved fluorescence spectroscopy was employed to characterize the equilibrium and non-equilibrium protein structural fluctuations in Zn II-substituted (ZnCytc) and metal-free (fbCytc) cytochromes c using dynamic fluorescence Stokes shift (FSS) and fluorescence anisotropy (FA) measurements. The intrinsic porphyrin chromophore is used as the probe for the structural fluctuations of the surrounding protein and solvent. The FSS experiments examine how the time scales detected from the dynamic solvation of a chromoprotein report changes in the character of motion. ZnCytc and fbCytc serve as limited, single-chromophore models for photosynthetic reaction center and light-harvesting proteins. The dynamic solvation of redox and light-harvesting chromophores in photosynthesis plays an important role in the quantum efficiency of electron transfer and energy transfer performed by these systems, respectively. The FSS response function of fbCytc in water is biexponential over the 100-ps--50-ns regime and the two time constants are 1.4 ns and 9.1 ns. ZnCytc under similar solution conditions shows a biexponential FSS response but with time constants of 0.2 ns and 1.5 ns. The two correlation times from the FSS response function correspond to motions of the hydrophobic core and the solvent-contact layer, respectively. Both FSS correlation times were lengthened and the solvation reorganization energy was reduced from 43 cm-1 to 33 cm-1 in the presence of 50% (v/v) glycerol. A Brownian diffusion model with thermally activated barrier crossings on the protein-folding energy landscape is used to interpret these results. The conclusion is that the mean-squared deviations of the fluctuations exhibited by fbCytc are perhaps a factor of ten larger than those in ZnCytc, which is consistent with the suggestion that fbCytc assumes a dynamic, partially unfolded structure with some of the characteristics of a molten globule. The nature of the motion associated with the

  14. Picosecond kinetics of p-dimethylaminobenzonitrile

    SciTech Connect

    Huppert, D.; Rand, S.D.; Rentzepis, P.M.; Barbara, P.F.; Struve, W.S.; Grabowski, Z.R.

    1981-12-15

    The nanosecond and picosecond resolved dual fluorescences of p-dimethylaminobenzonitrile (DAB), in various solvents and glasses excited by 266 nm 20 ps FWHM laser pulses, have been investigated. Pulse-limited rise times are exhibited by the b*-state emission whose decay in turn feeds directly the risetime of a*-state emission at 440--600 nm in most solvents studied. The a*-state emission was monitored at 520--600 nm in order to eliminate contribution from the b*-state. Within the experimental resolution, the b*-state fluorescence decay times vary approximately linearly with solvent viscosity. The a*-state fluorescence decay times vary with both solvent and temperature, and may reflect either thermally assisted intersystem crossing from the solvated singlet a*-state (presumably of twisted internal charge transfer character) to a corresponding solvated triplet of slightly higher energy, or a thermally activated internal conversion of the /sup 1/TICT to the ground state.

  15. Fundamentals of picosecond laser ultrasonics.

    PubMed

    Matsuda, Osamu; Larciprete, Maria Cristina; Li Voti, Roberto; Wright, Oliver B

    2015-02-01

    The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned.

  16. On the field evaporation behavior of a model Ni-Al-Cr superalloy studied by picosecond pulsed-laser atom-probe tomography.

    PubMed

    Zhou, Yang; Booth-Morrison, Christopher; Seidman, David N

    2008-12-01

    The effects of varying the pulse energy of a picosecond laser used in the pulsed-laser atom-probe (PLAP) tomography of an as-quenched Ni-6.5 Al-9.5 Cr at.% alloy are assessed based on the quality of the mass spectra and the compositional accuracy of the technique. Compared to pulsed-voltage atom-probe tomography, PLAP tomography improves mass resolving power, decreases noise levels, and improves compositional accuracy. Experimental evidence suggests that Ni2+, Al2+, and Cr2+ ions are formed primarily by a thermally activated evaporation process, and not by post-ionization of the ions in the 1+ charge state. An analysis of the detected noise levels reveals that for properly chosen instrument parameters, there is no significant steady-state heating of the Ni-6.5 Al-9.5 Cr at.% tips during PLAP tomography. PMID:18986610

  17. An infrared study of dust in Type IIn supernovae

    NASA Astrophysics Data System (ADS)

    Fox, Ori Dosovitz

    2010-11-01

    Given their high sensitivity to warm dust, infrared observations serve as important probes of supernovae and the surrounding supernova environment. Warm dust can trace progenitor mass loss rates, circumstellar interaction, and dust formation in the supernova environment, ultimately contributing to a broader understanding of stellar evolution, supernova explosion mechanics, and the origin of dust in the universe. The Type IIn supernova subclass, named for the "narrow" emission lines, tends to exhibit late-time infrared emission from warm dust more often than other subclasses. These supernovae, however, are particularly rare, consisting of only ˜2--3% of all core-collapse events. With only a handful of Type IIn observations at infrared wavelengths, the nature of the Type IIn environments and progenitors remain relatively unknown. This thesis presents an infrared study of Type IIn supernovae, beginning with a case study of SN 2005ip. A combination of Spitzer/IRS and IRAC, APO/TripleSpec, and FanCam data constrain the dust mass, temperature, and luminosity, identify the origin and heating mechanism of the warm dust, and characterize the progenitor system. Expanding on this work, a warm Spitzer/IRAC mission surveys the coordinates of 68 Type IIn supernovae within 250 Mpc from the past ten years. The detection of late-time emission from nine targets (>10%) nearly doubles the database of existing mid-infrared observations of Type IIn events. Pre-exisiting dust produced by massive progenitor eruptions (i.e., luminous blue variables) and heated by an infrared echo likely dominates the observed mid-infraraed flux. Finally, a characterization of the next generation of near-infrared detectors identifies several non-ideal noise sources and calibrations procedures. The resulting improvement in detector sensitivity paves the way for the next generation of transient observations as they trend towards cooler objects and higher redshifts.

  18. Study Of A Formulated Pesticide By Photoacoustic Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lowry, S. R.; Mead, D. G.; Vidrine, D. W.

    1981-10-01

    Photoacoustic infrared spectroscopy has been used to study the interactions of a carbamate insecticide with a clay carrier. The ability of photoacoustic infrared spectroscopy to measure infrared spectra from opaque samples non-destructively, is particularly valuable in this study where weak bonds might be destroyed by sample grinding. The results of this study show that the strong N-H stretching modes, which appear at approximately 3300 cm-1 in in the pure insecticide, are missing in the subtraction of the N-H group spectrum. This suggests that the hydrogen attached to the nitrogen of the carbamate is forming a reasonably strong bond with the hydrated silicate structure of the clay carrier. This interaction may effect the release rate of the pesticide upon application.

  19. Astronomical polarization studies at radio and infrared wavelengths. Part 2: Far infrared polarization of dust clouds

    NASA Technical Reports Server (NTRS)

    Dennison, B. K.

    1976-01-01

    Far infrared polarization of dust clouds is examined. The recently observed 10 micron polarization of the Orion Nebula and the Galactic Center suggests that far infrared polarization may be found in these objects. Estimates are made of the degree of far infrared polarization that may exist in the Orion Nebula. An attempt to observe far infrared polarization from the Orion Nebula was carried out.

  20. Studying infrared light therapy for treating Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Han, Mengmeng; Wang, Qiyan; Zeng, Yuhui; Meng, Qingqiang; Zhang, Jun; Wei, Xunbin

    2016-03-01

    Alzheimer's disease (AD) is an extensive neurodegenerative disease. It is generally believed that there are some connections between AD and amyloid protein plaques in the brain. AD is a chronic disease that usually starts slowly and gets worse over time. The typical symptoms are memory loss, language disorders, mood swings and behavioral issues. Gradual losses of somatic functions eventually lead patients to death. Currently, the main therapeutic method is pharmacotherapy, which may temporarily reduce symptoms, but has many side effects. No current treatment can reverse AD's deterioration. Infrared (IR) light therapy has been studied in a range of single and multiple irradiation protocols in previous studies and was found beneficial for neuropathology. In our research, we have verified the effect of infrared light on AD through Alzheimer's disease mouse model. This transgenic mouse model is made by co-injecting two vectors encoding mutant amyloid precursor protein (APP) and mutant presenilin-1 (PSEN1). We designed an experimental apparatus for treating mice, which primarily includes a therapeutic box and a LED array, which emits infrared light. After the treatment, we assessed the effects of infrared light by testing cognitive performance of the mice in Morris water maze. Our results show that infra-red therapy is able to improve cognitive performance in the mouse model. It might provide a novel and safe way to treat Alzheimer's disease.

  1. Laboratory infrared studies of molecules of atmospheric and astrophysical interest

    NASA Technical Reports Server (NTRS)

    Rao, N. N.

    1982-01-01

    Nineteen reprints on the molecular species are compiled. Much of the work was done by using the Doppler-limited resolution provided by diode lasers. The diode laser was used as a source to a grating spectrometer which has been used earlier for high resolution studies. This technique provided many advantages. Wherever possible, the studies have been directed to intensity determinations of infrared bands.

  2. Study on an infrared endoscope for energized laparoscopic method

    NASA Astrophysics Data System (ADS)

    Chen, Minghui; Song, Chengli

    2014-11-01

    An infrared endoscopic system has been developed to investigate thermal spread and collateral damage during energized laparoscopic surgery, the system consists of an infrared endoscope and a thermal camera (3-5 μm) with combined thermal sensitivity of 0.05°C. The system performance was evaluated in live animals with electrosurgical devices to monitor intraoperative thermal changes. During activation periods, the peak temperature of the jaws averaged 100.5 ± 5.8 ° with a thermal spread of 3.0 ± 0.9 mm. For laparoscopic dissections of the esophagus-gastric junction with the 10 mm Atlas, the maximum jaw temperature was 105.2 ± 2.1 ° with a bigger thermal spread of 11.5 ± 7.2 mm). The study has confirmed that infrared endoscopy is a very useful tool adjunct to conventional endoscopy, which may improve the safety of energized laparoscopic dissections.

  3. Flamingos near-infrared study of the Serpens cloud

    NASA Astrophysics Data System (ADS)

    Hasan, Priya

    We present the results of a deep near-infrared imaging survey of the Serpens Cloud made with FLAMINGOS at the 2.1 m telescope at Kitt Peak National Observatory. We study the distribution of young embedded sources using the nearest neighbor method applied to a carefully selected sample of near-infrared excess (NIRX) stars that trace the latest episode of star formation in the complex. Our analysis finds the existence of six clusters, of which three are new in the molecular cloud. We determined a median age for the cluster to be 1-2 Myr at a mean distance of 300 pc.

  4. Social Perception in Infancy: A Near Infrared Spectroscopy Study

    ERIC Educational Resources Information Center

    Lloyd-Fox, Sarah; Blasi, Anna; Volein, Agnes; Everdell, Nick; Elwell, Claire E.; Johnson, Mark H.

    2009-01-01

    The capacity to engage and communicate in a social world is one of the defining characteristics of the human species. While the network of regions that compose the social brain have been the subject of extensive research in adults, there are limited techniques available for monitoring young infants. This study used near infrared spectroscopy to…

  5. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  6. Study of Heat Transfer Dynamics from Gold Nanorods to the Environment via Time-Resolved Infrared Spectroscopy.

    PubMed

    Nguyen, Son C; Zhang, Qiao; Manthiram, Karthish; Ye, Xingchen; Lomont, Justin P; Harris, Charles B; Weller, Horst; Alivisatos, A Paul

    2016-02-23

    Studying the local solvent surrounding nanoparticles is important to understanding the energy exchange dynamics between the particles and their environment, and there is a need for spectroscopic methods that can dynamically probe the solvent region that is in nearby contact with the nanoparticles. In this work, we demonstrate the use of time-resolved infrared spectroscopy to track changes in a vibrational mode of local water on the time scale of hundreds of picoseconds, revealing the dynamics of heat transfer from gold nanorods to the local water environment. We applied this probe to a prototypical plasmonic photothermal system consisting of organic CTAB bilayer capped gold nanorods, as well as gold nanorods coated with varying thicknesses of inorganic mesoporous-silica. The heat transfer time constant of CTAB capped gold nanorods is about 350 ps and becomes faster with higher laser excitation power, eventually generating bubbles due to superheating in the local solvent. Silica coating of the nanorods slows down the heat transfer and suppresses the formation of superheated bubbles.

  7. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    NASA Astrophysics Data System (ADS)

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-02-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

  8. Picosecond resolution soft x-ray laser plasma interferometry

    SciTech Connect

    Moon, S; Nilsen, J; Ng, A; Shlyaptsev, V; Dunn, J; Hunter, J; Keenan, R; Marconi, M; Filevich, J; Rocca, J; Smith, R

    2003-12-01

    We describe a soft x-ray laser interferometry technique that allows two-dimensional diagnosis of plasma electron density with picosecond time resolution. It consists of the combination of a robust high throughput amplitude division interferometer and a 14.7 nm transient inversion soft x-ray laser that produces {approx} 5 ps pulses. Due to its picosecond resolution and short wavelength scalability, this technique has potential for extending the high inherent precision of soft x-ray laser interferometry to the study of very dense plasmas of significant fundamental and practical interest, such as those investigated for inertial confined fusion. Results of its use in the diagnostics of dense large scale laser-created plasmas are presented.

  9. INFRARED STUDY OF FULLERENE PLANETARY NEBULAE

    SciTech Connect

    Garcia-Hernandez, D. A.; Acosta-Pulido, J. A.; Manchado, A.; Garcia-Lario, P.; Stanghellini, L.; Shaw, R. A.; Cataldo, F. E-mail: amt@iac.es E-mail: Pedro.Garcia-Lario@sciops.esa.int E-mail: letizia@noao.edu

    2012-12-01

    We present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in the Large Magellanic Cloud (LMC), and seven in the Small Magellanic Cloud (SMC). Among the 16 PNe studied, we present the first detection of C{sub 60} (and possibly also C{sub 70}) fullerenes in the PN M 1-60 as well as of the unusual {approx}6.6, 9.8, and 20 {mu}m features (attributed to possible planar C{sub 24}) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity ({approx}5% in the Galaxy, {approx}20% in the LMC, and {approx}44% in the SMC) and we interpret this as a possible consequence of the limited dust processing occurring in Magellanic Cloud (MC) PNe. CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature ({approx}30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. Furthermore, the data suggest that fullerene PNe likely evolve from low-mass progenitors and are usually of low excitation. We do not find a metallicity dependence on the estimated fullerene abundances. The observed C{sub 60} intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [Ne III]/[Ne II] ratios using photoionization, suggesting that possibly the UV radiation from the central star, and

  10. Metal nanofilms studied with infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Fahsold, Gerhard; Priebe, Andreas; Pucci, Annemarie; Otto, Andreas

    2006-03-01

    Metal films with thickness in the nanometer range are optically transparent. In the IR range their transmittance may show both the Drude-type behaviour of coalesced islands and the tail of the plasmon absorption of single islands. Therefore, IR transmittance spectroscopy is a sensitive tool for in-situ studies of metal-film growth on insulating substrates and of the film conductivity. With IR transmittance spectroscopy the in-plane film conductivity and its correlation to the film-growth process can be determined without electrical contacts. Adsorbate induced changes can be observed well. Their analysis may give insight into the adsorbate-metal bonding. Depending on the film's roughness the IR lines of adsorbate-vibration modes may be strongly modified because of their interaction with electronic excitations of the film. The atomic roughness of cold-condensed metal films produces additional IR activity: strong IR activity of Raman lines of centrosymmetric adsorbate molecules is observed in those cases where the adsorbate has states close to the Fermi level.

  11. Femtosecond-picosecond laser photolysis studies on the dynamics of excited charge-transfer complexes: Aromatic hydrocarbon-acid anhydride, -tetracyanoethylene, and -tetracyanoquinodimethane systems in acetonitrile solutions

    SciTech Connect

    Asahi, Tsuyoshi; Mataga, Noboru )

    1991-03-07

    Formation processes of contact ion pairs (CIP) from the excited Franck-Condon (FC) state of charge-transfer (CT) complexes of aromatic hydrocarbons with acid anhydride as well as cyano compound acceptors in acetonitrile solution and charge recombination (CR) rates (k{sub CR}{sup CIP}) of produced CIP states have been investigated by femtosecond and picosecond laser phototlysis and time-resolved absorption spectral measurements covering a wide range of free energy gap-{Delta}G{degree}{sub ip} between the ion pair and the ground state. It has been confirmed that the CIP formation becomes faster and k{sub CR}{sup CIP} of the produced CIP increases with increase of the strengths of the electron donor (D) and acceptor (A) in the complex, i.e., with decrease of the {minus}{Delta}G{degree}{sub ip} value. This peculiar energy gap dependence of k{sub CR}{sup CIP}, quite different from the bell-shaped one observed in the case of the solvent-separated ion pairs (SSIP) or loose ion pairs (LIP) formed by encounter between fluorescer and quencher in the fluoresence quenching reaction, has been interpreted by assuming the change of electronic and geometrical structures of CIP depending on the strengths of D and A.

  12. Picosecond and nanosecond studies of the photoreduction of benzophenone by 1,4-diazabicyclo(2. 2. 2)octane: Characterization of the transient

    SciTech Connect

    Devadoss, C.; Fessenden, R.W. )

    1990-05-31

    The transient that is produced in the quenching of triplet benzophenone by 1,4-diazabicyclo(2.2.2)octane (DABCO) has been examined by use of nano- and picosecond laser photolysis. The initial step in all solvents, both polar and nonpolar, is electron transfer to form a triplet contact ion pair. In nonpolar solvents, the ion pair remains in this form until it decays. For polar solvents, the spectra change somewhat over the first 100 ps showing that the solvation changes and the ion pair becomes solvent separated. The lifetime of the ion pair varies greatly with the solvent. In saturated hydrocarbons it is about 80 ps. Nonpolar solvents with either {pi} electrons or a lone pair of electrons stabilize the ion pair on the nanosecond to microsecond time scale. A small amount of alcohol in benzene also stabilizes the ion pair by hydrogen bonding. A shift in the peak position with time toward the blue accompanies the formation of hydrogen bonds in this case.

  13. Infrared Structural Biology: Detect Functionally Important Structural Motions of Proteins

    NASA Astrophysics Data System (ADS)

    Xie, Aihua

    Proteins are dynamic. Lack of dynamic structures of proteins hampers our understanding of protein functions. Infrared structural biology (IRSB) is an emerging technology. There are several advantages of IRSB for mechanistic studies of proteins: (1) its excellent dynamic range (detecting structural motions from picoseconds to >= seconds); (2) its high structural sensitivity (detect tiny but functionally important structural motions such as proton transfer and changes in hydrogen bonding interaction); (3) its ability to detect different structural motions simultaneously. Successful development of infrared structural biology demands not only new experimental techniques (from infrared technologies to chemical synthesis and cell biology), but also new data processing (how to translate infrared signals into quantitative structural information of proteins). These topics will be discussed as well as examples of how to use IRSB to study structure-function relationship of proteins. This work was supported by NSF DBI1338097 and OCAST HR10-078.

  14. Comprehensive Infrared Study of Tetryl, Dinitrotoluene, and Trinitrotoluene Compounds.

    PubMed

    Puiu, Adriana; Giubileo, Gianfranco; Cesaro, Stella Nunziante; Bencivenni, Luigi

    2015-12-01

    The present work describes an experimental and theoretical study of energetic materials used for detecting explosives in order to prevent terrorist actions, as well as for de-mining projects. Particular attention was devoted to examining the infrared absorption spectroscopy of classic explosives in order to create a useful mobile apparatus for on-field detection of explosives. This paper reports the vibrational absorption spectra of tetryl, dinitrotoluene, and trinitrotoluene molecules approached using two different spectroscopic techniques, Fourier transform infrared spectroscopy (FT-IR) and laser photoacoustic spectroscopy (LPAS). Diffuse reflectance Fourier transform infrared spectra of all samples were analyzed in a very wide spectral range (400-7500 cm(-1)) showing for the first time the existence of weak absorption bands attributable to overtones or combination bands, while laser photoacoustic spectroscopy spectra have been investigated in the fingerprint region of organic compounds that share the CO2 laser emission range (~920-1100 cm(-1)). The Fourier transform infrared spectra of both matrix isolated dinitrotoluenes have been also investigated. The theoretical treatment of tetryl is reported for the first time.

  15. Conceptual design study for Infrared Limb Experiment (IRLE)

    NASA Technical Reports Server (NTRS)

    Baker, Doran J.; Ulwick, Jim; Esplin, Roy; Batty, J. C.; Ware, Gene; Tew, Craig

    1989-01-01

    The phase A engineering design study for the Infrared Limb Experiment (IRLE) instrument, the infrared portion of the Mesosphere-Lower Thermosphere Explorer (MELTER) satellite payload is given. The IRLE instrument is a satellite instrument, based on the heritage of the Limb Infrared Monitor of the Stratosphere (LIMS) program, that will make global measurements of O3, CO2, NO, NO2, H2O, and OH from earth limb emissions. These measurements will be used to provide improved understanding of the photochemistry, radiation, dynamics, energetics, and transport phenomena in the lower thermosphere, mesosphere, and stratosphere. The IRLE instrument is the infrared portion of the MELTER satellite payload. MELTER is being proposed to NASA Goddard by a consortium consisting of the University of Michigan, University of Colorado and NASA Langley. It is proposed that the Space Dynamics Laboratory at Utah State University (SDL/USU) build the IRLE instrument for NASA Langley. MELTER is scheduled for launch in November 1994 into a sun-synchronous, 650-km circular orbit with an inclination angle of 97.8 deg and an ascending node at 3:00 p.m. local time.

  16. Shaping pulses using frequency conversion with a modulated picosecond free electron laser

    SciTech Connect

    Hooper, B.A.; Madey, J.M.J.

    1995-12-31

    Computer simulations and experiments indicate that we can shape the infrared picosecond pulses of the Mark III FEL in amplitude, frequency, and phase. Strongly modulated fundamental and second harmonic pulses have been generated by operating the Mark III FEL in the regime of strong sideband growth. In this paper, we present the results of simulations and experiments for second harmonic generation with fundamental inputs from 2 to 3 {mu}m.

  17. Investigations of morphological features of picosecond dual-wavelength laser ablation of stainless steel

    NASA Astrophysics Data System (ADS)

    Zhao, Wanqin; Wang, Wenjun; Mei, Xuesong; Jiang, Gedong; Liu, Bin

    2014-06-01

    Investigations on the morphological features of holes and grooves ablated on the surface of stainless steel using the picosecond dual-wavelength laser system with different powers combinations are presented based on the scarce researches on morphology of dual-wavelength laser ablation. The experimental results show the profiles of holes ablated by the visible beam appear V-shaped while those for the near-infrared have large openings and display U-shaped, which are independent of the ablation mechanism of ultrafast laser. For the dual-wavelength beam (a combination of visible beam and near-infrared), the holes resemble sunflower-like structures and have smoother ring patterns on the bottom. In general, the holes ablated by the dual-wavelength beam appear to have much flatter bottoms, linearly sloped side-walls and spinodal structures between the bottoms of the holes and the side-walls. Furthermore, through judiciously combining the powers of the dual-wavelength beam, high-quality grooves could be obtained with a flat worm-like structure at the bottom surface and less resolidified melt ejection edges. This study provides insight into optimizing ultrafast laser micromachining in order to obtain desired morphology.

  18. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect

    Sawyer, Karma Rae

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  19. Analysis of Picosecond Pulsed Laser Melted Graphite

    DOE R&D Accomplishments Database

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  20. The Stanford Picosecond FEL Center

    SciTech Connect

    Schwettman, H.A.; Smith, T.I.; Swent, R.L.

    1995-12-31

    In the past two years, FELs have decisively passed the threshold of scientific productivity. There are now six FEL facilities in the United States and Europe, each delivering more than 2000 hours of FEL beam time per year. at the present time approximately 100 papers are published each in referred journals describing optics experiments performed with FELs. Despite the recent success there are important challenges the FEL facilities must address. At Stanford these challenges include: (1) Providing sufficient experimental time at reasonable cost: At Stanford we provide 2000 hours of experimental time per year at a cost of approximately $500 per hour: We are now studying options for markedly increasing experimental time and decreasing cost per hour. (2) Competing effectively with conventional lasers in the mid-IR: Despite the NRC report we do not intend to concede the mid-IR to conventional lasers. FELs are capable of providing optical beams of exceptional quality and stability, and they can also be remarkable flexible devices. Improvements in our superconducting linac driver and our optical beam conditioning systems will dramatically enhance our FEL experimental capabilities. (3) making the transition from first generation to second generation experiments: Important pump-probe and photon echo experiments have been performed at Stanford and others are feasible using present capabilities. None-the-less we are now investing substantial experimental time to improving signal-to-noise and developing other optical cababilities. (4) Extending operation to the far-infrared where the FEL is unique inits capabilities: {open_quotes}FIREFLY{close_quotes} will extend our FEL capabilities to 100 microns. We are now seeking funds for optical instrumentation. (5) Creating and maintaining a good environment for graduate students.

  1. Combined infrared and Raman study of solid CO

    NASA Astrophysics Data System (ADS)

    Urso, R. G.; Scirè, C.; Baratta, G. A.; Compagnini, G.; Palumbo, M. E.

    2016-10-01

    Context. Knowledge about the composition and structure of interstellar ices is mainly based on the comparison between astronomical and laboratory spectra of astrophysical ice analogues. Carbon monoxide is one of the main components of the icy mantles of dust grains in the interstellar medium. Because of its relevance, several authors have studied the spectral properties of solid CO both pure and in mixtures. Aims: The aim of this work is to study the profile (shape, width, peak position) of the solid CO band centered at about 2140 cm-1 at low temperature, during warm up, and after ion irradiation to search for a structural variation of the ice sample. We also report on the appearance of the longitudinal optical-transverse optical (LO-TO) splitting in the infrared spectra of CO films to understand if this phenomenon can be related to a phase change. Methods: We studied the profile of the 2140 cm-1 band of solid CO by means of infrared and Raman spectroscopy. We used a free web interface that we developed that allows us to calculate the refractive index of the sample to measure the thickness of the film. Results: The profile of the fundamental band of solid CO obtained with infrared and Raman spectroscopy does not show any relevant modification after warm up or ion bombardment in the dose range investigated. We explain that the LO-TO splitting is not connected to a structural variation of the film. Ion irradiation causes the formation of new molecular species. Raman spectroscopy allowed us to detect, among other bands, a band centered at 1817 cm-1 that has been attributed to the infrared inactive species C2 and a band centered at 1767 cm-1 that remains unidentified.

  2. Dielectric breakdown induced by picosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

    1976-01-01

    The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger.

  3. Picosecond dynamics from lanthanide chloride melts

    NASA Astrophysics Data System (ADS)

    Kalampounias, Angelos G.

    2012-12-01

    The picosecond dynamics of molten lanthanide chlorides is studied by means of vibrational spectroscopy. Polarized Raman spectra of molten LaCl3, NdCl3, GdCl3, DyCl3, HoCl3 and YCl3 are fitted to a model enabling to obtain the times of vibrational dephasing, tν and vibrational frequency modulation tω. Our aim is to find possible sensitive indicators of short-time dynamics. It has been found that all lanthanide chlorides exhibit qualitative similarities in the vibrational relaxation and frequency modulation times in the molten state. It appears that the vibrational correlation functions of all melts comply with the Rothschild approach assuming that the environmental modulation is described by a stretched exponential decay. The evolution of the dispersion parameter α indicates the deviation of the melts from the model simple liquid and the similar local environment in which the oscillator is placed and with which it is coupled. The "packing" of the anions around central La3+ cation seems to be the key factor for the structure and the dynamics of the melts. The results are discussed in the framework of the current phenomenological status of the field.

  4. Picosecond lasers with the dynamical operation control

    NASA Astrophysics Data System (ADS)

    Mikheev, N. G.; Morozov, V. B.; Olenin, A. N.; Yakovlev, D. V.

    2016-04-01

    Numerical model for simulation of generation process in advanced pulse-periodic high-peak-power picosecond diode-pumped Nd:YAG and Nd:YLF lasers has been developed. The model adequately describes picosecond pulse formation governed by active and passive mode-locking, negative feedback and adjustable loss level in the oscillator cavity. Optical jitter of output pulses attributed to laser generation development from spontaneous noise level was evaluated using statistical analysis of calculation results. In the presented laser scheme, minimal jitter value on the level ~40 ps was estimated.

  5. Study of oral cavity lesions by infrared spectroscopy.

    PubMed

    Giorgini, E; Conti, C; Rocchetti, R; Rubini, C; Sabbatini, S; Librando, V; Tosi, G

    2016-01-01

    Fourier transform infrared (FTIR) microspectroscopy is considered a useful tool in the biomedical field, for analysing in situ and at cellular level, very small areas of tissues and cells, with minimal sample preparation and without the use of stains or probes. This spectroscopic technique has been successfully applied to analyse biological samples from patients affected by tumoral pathologies, with particular attention to oral cavity lesions. In this study, we describe the application of FTIR microspectroscopy to characterize and discriminate the most recurrent benign and malignant diseases of oral cavity compartment. Infrared maps were acquired on tissues affected by the following pathologies: squamous cell carcinoma, adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, squamous dysplasia, keratocystic odontogenic tumor, radicular cyst, residual cyst, unicystic ameloblastoma, and ameloblastic fibroma, together with healthy tissue samples (used as control group). The epithelial and connective components of all samples were distinguished and submitted to multivariate analysis. The results were in agreement with histological suggestions. PMID:27049108

  6. High-power picosecond laser diodes based on different methods of fast gain control for high-precision radar applications

    NASA Astrophysics Data System (ADS)

    Vainshtein, Sergey; Kostamovaara, Juha; Lantratov, Vladimir; Kaluzhniy, Nikolay; Mintairov, Sergey

    2007-05-01

    Current-pumped picosecond-range laser diodes with a peak power significantly exceeding that achievable from gainswitched lasers are of major interest for a large variety of commercial applications. A group of phenomena have been explored in which the peak transient gain is efficiently controlled by a fast reduction in the pumping current. Common to all these phenomena is the fact that the peak powers of the emitted picosecond optical pulses (15-100 ps) exceed that obtainable from gain-switched laser diodes by at least an order of magnitude, although the physical reasons for the high gain and the design principles of the semiconductor structures are different. The main problem in the realization of these picosecond modes in low-cost practical systems is the high sensitivity of the operation regime to structural and circuit parameters. A related problem is the questionable reproducibility of the fabrication processes used so far. Proper development of reliable high-power picosecond transmitters will require the use of more advanced fabrication methods and further study of the effect of structural parameters on the properties of the picosecond lasing mode. In this paper we report on a record value for the power density of the picosecond lasing (50W / 30ps) obtained from a laser diode chip of width 20 μm and give a qualitative interpretation of the operating mode. Use of the MOCVD process for diode fabrication should allow reproducible technology for picosecond laser diodes to be developed.

  7. Studies of planetary boundary layer by infrared thermal imagery

    SciTech Connect

    Albina, Bogdan; Dimitriu, Dan Gheorghe Gurlui, Silviu Octavian; Cazacu, Marius Mihai; Timofte, Adrian

    2014-11-24

    The IR camera is a relatively novel device for remote sensing of atmospheric thermal processes from the Planetary Boundary Layer (PBL) based on measurements of the infrared radiation. Infrared radiation is energy radiated by the motion of atoms and molecules on the surface of aerosols, when their temperature is more than absolute zero. The IR camera measures directly the intensity of radiation emitted by aerosols which is converted by an imaging sensor into an electric signal, resulting a thermal image. Every image pixel that corresponds to a specific radiance is pre-processed to identify the brightness temperature. The thermal infrared imaging radiometer used in this study, NicAir, is a precision radiometer developed by Prata et al. The device was calibrated for the temperature range of 270–320 K and using a calibration table along with image processing software, important information about variations in temperature can be extracted from acquired IR images. The PBL is the lowest layer of the troposphere where the atmosphere interacts with the ground surfaces. The importance of PBL lies in the fact that it provides a finite but varying volume in which pollutants can disperse. The aim of this paper is to analyze the PBL altitude and thickness variations over Iasi region using the IR imaging camera as well as its behavior from day to night and thermal processes occurring in PBL.

  8. Studies of planetary boundary layer by infrared thermal imagery

    NASA Astrophysics Data System (ADS)

    Albina, Bogdan; Cazacu, Marius Mihai; Timofte, Adrian; Dimitriu, Dan Gheorghe; Gurlui, Silviu Octavian

    2014-11-01

    The IR camera is a relatively novel device for remote sensing of atmospheric thermal processes from the Planetary Boundary Layer (PBL) based on measurements of the infrared radiation. Infrared radiation is energy radiated by the motion of atoms and molecules on the surface of aerosols, when their temperature is more than absolute zero. The IR camera measures directly the intensity of radiation emitted by aerosols which is converted by an imaging sensor into an electric signal, resulting a thermal image. Every image pixel that corresponds to a specific radiance is pre-processed to identify the brightness temperature. The thermal infrared imaging radiometer used in this study, NicAir, is a precision radiometer developed by Prata et al. The device was calibrated for the temperature range of 270-320 K and using a calibration table along with image processing software, important information about variations in temperature can be extracted from acquired IR images. The PBL is the lowest layer of the troposphere where the atmosphere interacts with the ground surfaces. The importance of PBL lies in the fact that it provides a finite but varying volume in which pollutants can disperse. The aim of this paper is to analyze the PBL altitude and thickness variations over Iasi region using the IR imaging camera as well as its behavior from day to night and thermal processes occurring in PBL.

  9. Studies of dust grain properties in infrared reflection nebulae.

    PubMed

    Pendleton, Y J; Tielens, A G; Werner, M W

    1990-01-20

    We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light. PMID:11538693

  10. [Near infrared spectroscopy study on water content in turbine oil].

    PubMed

    Chen, Bin; Liu, Ge; Zhang, Xian-Ming

    2013-11-01

    Near infrared (NIR) spectroscopy combined with successive projections algorithm (SPA) was investigated for determination of water content in turbine oil. Through the 57 samples of different water content in turbine oil scanned applying near infrared (NIR) spectroscopy, with the water content in the turbine oil of 0-0.156%, different pretreatment methods such as the original spectra, first derivative spectra and differential polynomial least squares fitting algorithm Savitzky-Golay (SG), and successive projections algorithm (SPA) were applied for the extraction of effective wavelengths, the correlation coefficient (R) and root mean square error (RMSE) were used as the model evaluation indices, accordingly water content in turbine oil was investigated. The results indicated that the original spectra with different water content in turbine oil were pretreated by the performance of first derivative + SG pretreatments, then the selected effective wavelengths were used as the inputs of least square support vector machine (LS-SVM). A total of 16 variables selected by SPA were employed to construct the model of SPA and least square support vector machine (SPA-LS-SVM). There is 9 as The correlation coefficient was 0.975 9 and the root of mean square error of validation set was 2.655 8 x 10(-3) using the model, and it is feasible to determine the water content in oil using near infrared spectroscopy and SPA-LS-SVM, and an excellent prediction precision was obtained. This study supplied a new and alternative approach to the further application of near infrared spectroscopy in on-line monitoring of contamination such as water content in oil.

  11. Studies of dust grain properties in infrared reflection nebulae.

    PubMed

    Pendleton, Y J; Tielens, A G; Werner, M W

    1990-01-20

    We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light.

  12. High spatial resolution mid-infrared studies of planetary systems

    NASA Astrophysics Data System (ADS)

    Skemer, Andrew

    I present the results of six papers related the formation and evolution of planets and planetary systems, all of which are based on high-resolution, ground-based, mid-infrared observations. The first three chapters are studies of T Tauri binaries. T Tauri stars are young, low mass stars, whose disks form the building blocks of extrasolar planets. The first chapter is a study of the 0.68"/0.12" triple system, T Tauri. Our spatially resolved N-band photometry reveals silicate absorption towards one component, T Tau Sa, indicating the presence of an edge-on disk, which is in contrast to the other components. The second chapter is an adaptive optics fed N-band spectroscopy study of the 0.88" binary, UY Aur. We find that the dust grains around UY Aur A are ISM-like, while the mineralogy of the dust around UY Aur B is more uncertain, due to self-extinction. The third chapter presents a survey of spatially resolved silicate spectroscopy for nine T Tauri binaries. We find with 90%-95% confidence that the silicate features of the binaries are more similar than those of randomly paired single stars. This implies that a shared binary property, such as age or composition, is an important parameter in dust grain evolution. The fourth chapter is a study of the planetary system, 2MASS 1207. We explore the source of 2MASS 1207 b's under-luminosity, which has typically been explained as the result of an edge-on disk of large, grey-extincting dust grains. We find that the edge-on disk theory is incompatible with several lines of evidence, and suggest that 2MASS 1207 b's appearance can be explained by a thick cloudy atmosphere, which might be typical among young, planetary systems. The fifth chapter is a study of the white dwarf, Sirius B, which in the context of this thesis is being studied as a post-planetary system. Our N-band imaging demonstrates that Sirius B does not have an infrared excess, in contrast to previous results. The sixth chapter is a study of mid-infrared

  13. Infrared Imaging, Spectroscopic, and Photometric Studies of Comets

    NASA Technical Reports Server (NTRS)

    Gehrz, Robert D.

    1997-01-01

    We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have

  14. Experimental study of infrared filaments under different initial conditions

    NASA Astrophysics Data System (ADS)

    Mirell, Daniel Joseph

    In 1964, four years after the first working laser was constructed, long skinny damage tracks and fluorescence trails were seen inside of certain transparent media that were excited by intense light pulses [1]. What was so remarkable about these features was the narrowness of the spatial profile and their long propagation length in the beam in concert with the very high intensity of the light that would be necessary to produce them. A purely linear model of light propagation through such media was insufficient to explain the results of these experiments and hence a new area of nonlinear optics, latex coined filamentation (to describe the length, slimness, and intensity of the light field), was born. Filament studies begin with a medium that has a nonlinear index of refraction, n¯2, that interacts with an intense beam of light so as to cause it to self-focus. The n¯2 of liquid and solid transparent media is much higher than the n¯ 2 of gases and therefore a much higher intensity of laser source would need to be invented to begin the study of filaments in air. With the advent of the Ti-Sapphire Kerr-lens modelocked laser [2], working in combination with the development of the chirped pulse amplifier system in the mid-1990's, light intensities sufficient to produce filaments in air was realized. Since that time much experimental and theoretical work has been done to better understand some of the additional complexities that arise specifically in the filamentation of light in air using several different wavelengths (UV to IR) and pulsewidths (femto- to pico-seconds). Many theoretical models exist each with a different emphasis on the various physical mechanisms that may produce the features experimentally observed in filaments. The experimental work has sought to give the theoretician better data on some of the properties of filaments such as the: (a) spatial and temporal structure of the beam and of the produced plasma (that arises due to the high intensity light

  15. Infrared absorption study of neutron-transmutation-doped germanium

    NASA Technical Reports Server (NTRS)

    Park, I. S.; Haller, E. E.

    1988-01-01

    Using high-resolution far-infrared Fourier transform absorption spectroscopy and Hall effect measurements, the evolution of the shallow acceptor and donor impurity levels in germanium during and after the neutron transmutation doping process was studied. The results show unambiguously that the gallium acceptor level concentration equals the concentration of transmutated Ge-70 atoms during the whole process indicating that neither recoil during transmutation nor gallium-defect complex formation play significant roles. The arsenic donor levels appear at full concentration only after annealing for 1 h at 450 C. It is shown that this is due to donor-radiation-defect complex formation. Again, recoil does not play a significant role.

  16. A femtosecond visible/visible and visible/mid-infrared transient absorption study of the light harvesting complex II.

    PubMed

    Stahl, Andreas D; Di Donato, Mariangela; van Stokkum, Ivo; van Grondelle, Rienk; Groot, Marie Louise

    2009-12-16

    Light harvesting complex II (LHCII) is the most abundant protein in the thylakoid membrane of higher plants and green algae. LHCII acts to collect solar radiation, transferring this energy mainly toward photosystem II, with a smaller amount going to photosystem I; it is then converted into a chemical, storable form. We performed time-resolved femtosecond visible pump/mid-infrared probe and visible pump/visible probe absorption difference spectroscopy on purified LHCII to gain insight into the energy transfer in this complex occurring in the femto-picosecond time regime. We find that information derived from mid-infrared spectra, together with structural and modeling information, provides a unique visualization of the flow of energy via the bottleneck pigment chlorophyll a604.

  17. Optical Studies on Antimonide Superlattice Infrared Detector Material

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Soibel, Alexander; Hill, Cory J.; Ting, David Z.; Khoshakhlagh, Arezou; Liao, Anna; Keo, Sam; Lee, Michael C.; Nguyen, Jean; Mumolo, Jason M.; Gunapala, Sarath D.

    2010-01-01

    In this study the material quality and optical properties of type II InAs/GaSb superlattices are investigated using transmission and photoluminescence (PL) spectroscopy. The influence of the material quality on the intensity of the luminescence and on the electrical properties of the detectors is studied and a good correlation between the photodetector current-voltage (IV) characteristics and the PL intensity is observed. Studies of the temperature dependence of the PL reveal that Shockley-Read-Hall processes are limiting the minority carrier lifetime in both the mid-IR wavelength and the long-IR wavelength detector material studied. These results demonstrate that PL spectroscopy is a valuable tool for optimization of infrared detectors.

  18. Study on laser and infrared attenuation performance of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-cui; Liu, Qing-hai; Dai, Meng-yan; Cheng, Xiang; Fang, Guo-feng; Zhang, Tong; Liu, Haifeng

    2014-11-01

    In recent years, the weapon systems of laser and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. However, military smoke, a rapid and effective passive jamming method, can effectively counteract the attack of precision-guided weapons by their scattering and absorbing effects. The traditional smoke has good visible light (0.4-0.76μm) obscurant performance, but hardly any effects to other electromagnetic wave bands while the weapon systems of laser and IR imaging guidance usually work in broad band, including the near-infrared (1-3μm), middle-infrared (3-5μm), far-infrared (8-14μm), and so on. Accordingly, exploiting new effective obscurant materials has attracted tremendous interest worldwide nowadays. As is known, the nano-structured materials have lots of unique properties comparing with the traditional materials suggesting that they might be the perfect alternatives to solve the problems above. Carbon nanotubes (CNTs) are well-ordered, all-carbon hollow graphitic nano-structured materials with a high aspect ratio, lengths from several hundred nanometers to several millimeters. CNTs possess many unique intrinsic physical-chemical properties and are investigated in many areas reported by the previous studies. However, no application research about CNTs in smoke technology field is reported yet. In this paper, the attenuation performances of CNTs smoke to laser and IR were assessed in 20m3 smoke chamber. The testing wavebands employed in experiments are 1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. The main parameters were obtained included the attenuation rate, transmission rate, mass extinction coefficient, etc. The experimental results suggest that CNTs smoke exhibits excellent attenuation ability to the broadband IR radiation. Their mass extinction coefficients are all above 1m2·g-1. Nevertheless, the mass extinction coefficients vary with the sampling time

  19. 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)

  20. Long life feasibility study for the shuttle infrared telescope facility

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A study was conducted to assess the feasibility of designing an Infrared Telescope of the 1 meter class which would operate effectively as a Shuttleborne, 14-day Spacelab payload and then be adapted with little modification to work as a 6 month Space station or free flyer payload. The optics configuration and requirements from a previous study were used without modification. In addition, an enhancement to 2 year mission lengths was studied. The cryogenic system selected was a hybrid design with an internal solid Hydrogen tank at 8 Kelvin and an internal superfluid tank at 2K. In addition to the cryogenic design, a detailed look at secondary mirror actuators for chopping, focus and decenter was conducted and analysis and cryo test reported.

  1. Tunable Infrared Laser Instruments for Airborne Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Fried, A.; Diskin, G.; Weibring, P.; Richter, D.; Walega, J. G.; Sachse, G.; Slate, T.; Rana, M.; Podolske, J.

    2008-01-01

    Tunable infrared laser-based instruments on airborne platforms have provided invaluable contributions to atmospheric studies over the past several decades. This paper presents an overview of some recent studies and developments using this approach that were presented at the 2007 Field Laser Applications in Industry and Research (FLAIR, http://www.inoa.it/flair/) conference in Florence, Italy. The present overview only covers select in situ absorption-based instruments that were presented in the airborne session at this conference. In no case are comprehensive details presented. These details can be found in the numerous references given. Additional approaches based upon cavity-enhanced and photoacoustic measurements, which are also making invaluable contributions in airborne atmospheric studies, are not discussed in this brief overview.

  2. The molecular structure of chloritoid: a mid-infrared and near-infrared spectroscopic study.

    PubMed

    Li, Kuo; Liu, Qinfu; Cheng, Hongfei; Deng, Yutao; Frost, Ray L

    2015-06-15

    The mineral chloritoid collected from the argillite in the bottom of Yaopo Formation of Western Beijing was characterized by mid-infrared (MIR) and near-infrared (NIR) spectroscopy. The MIR spectra showed all fundamental vibrations including the hydroxyl units, basic aluminosilicate framework and the influence of iron on the chloritoid structure. The NIR spectrum of the chloritoid showed combination (ν+δ)OH bands with the fundamental stretching (ν) and bending (δ) vibrations. Based on the chemical component data and the analysis result from the MIR and NIR spectra, the crystal structure of chloritoid from western hills of Beijing, China, can be illustrated. Therefore, the application of the technique across the entire infrared region is expected to become more routine and extend its usefulness, and the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for the unit cell structural analysis.

  3. Tunable Far Infrared Studies in Support of Stratospheric Measurements

    NASA Technical Reports Server (NTRS)

    Chance, Kelly V.; Park, K.; Nolt, I. G.; Evenson, K. M.

    2001-01-01

    This report summarizes research done under NASA Grant NAG5-4653. The research performed under this grant has been a collaboration between institutions including the Smithsonian Astrophysical Observatory, the National Institute of Standards and Technology, the University of Oregon, and the NASA Langley Research Center. The program has included fully line-resolved measurements of submillimeter and far infrared spectroscopic line parameters (pressure broadening coefficients and their temperature dependences, and line positions) for the analysis of field measurements of stratospheric constituents, far infrared database improvements, and studies for improved satellite measurements of the Earth's atmosphere. This research program is designed to enable the full utilization of spectra obtained in far infrared/submillimeter field measurements, such as FIRS-2, FILOS, IBEX, SLS, EosMLS, and proposed European Space Agency measurements of OH (e.g., PIRAMHYD and SFINX) for the retrieval of accurate stratospheric altitude profiles of key trace gases involved in ozone layer photochemistry. For the analysis of the spectra obtained in the stratosphere from far infrared measurements it is necessary to have accurate values of the molecular parameters (line positions, strengths, and pressure broadening coefficients) for the measured molecules and for possible interfering species. Knowledge of line positions is in increasingly good shape, with some notable exceptions. The increase in position information includes research that has been performed in the present program of research on HO2, H2O, H2O2, O3, HCl, HF, HBr, HI, CO, OH, and ClO. Examples where further line position studies are necessary include hot band and minor isotopomer lines of some of the major trace species (H2O, O3) and normal lines of some triatomic and larger molecules (NO2). Knowledge of strengths is in generally good shape, since most of the lines are from electric dipole transitions whose intensities are well

  4. Laser ablation of CFRP using picosecond laser pulses at different wavelengths from UV to IR

    NASA Astrophysics Data System (ADS)

    Wolynski, Alexander; Herrmann, Thomas; Mucha, Patrick; Haloui, Hatim; L'huillier, Johannes

    Laser processing of carbon fibre reinforced plastics (CFRP) has a great industrial relevance for high performance structural parts in airplanes, machine tools and cars. Through-holes drilled by nanosecond laser pulses show thermal induced molten layers and voids. Recently, picosecond lasers have demonstrated the ability to drill high-efficient and high-quality rivet through-holes. In this paper a high-power picosecond laser system operating at different wavelengths (355 nm, 532 nm and 1064 nm) has been used for CFRP ablation experiments to study the influence of different laser parameters in terms of machining quality and processing time.

  5. Picosecond pulsed diode ring laser gyroscope

    SciTech Connect

    Rosker, M.J.; Christian, W.R.; McMichael, I.C.

    1994-12-31

    An external ring cavity containing as its active medium a pair of InGaAsP diodes is modelocked to produce picosecond pulses. In such a laser, a small frequency difference proportional to the nonreciprocal phase shift (resulting from, e.g., the Sagnac effect) can be observed by beating together the counter propagating laser arms; the device therefore acts as a rotating sensor. In contrast to a conventional (cw) ring laser gyroscope, the pulsed gyroscope can avoid gain competition, thereby enabling the use of homogeneously broadened gain media like semiconductor diodes. Temporal separation of the pulses within the cavity also discriminates against frequency locking of the lasers. The picosecond pulsed diode ring laser gyroscope is reviewed. Both active and passive modelocking are discussed.

  6. Interstellar ices studied with the Infrared Space Observatory.

    PubMed

    Whittet, D C

    1997-06-01

    The Infrared Space Observatory (ISO) was launched by the European Space Agency on 17 November 1995. The availability of spectra from the Short Wavelength Spectrometer (SWS) on ISO is a landmark in the study of interstellar ices and organics; they provide a wealth of data in the 2-20 microns region of the spectrum covering the principal solid state resonances of condensed matter in interstellar clouds. We thus have the opportunity to study many species likely to be relevant to the inventory of CNO-bearing interstellar material present at the formation of our own and other planetary systems. This paper presents a brief overview of what has been learned from the data available so far. A comparison is made between the compositions of ices in molecular clouds, protostellar condensations and comets. Key areas of uncertainty are highlighted as a basis for future research.

  7. High Power Picosecond Laser Pulse Recirculation

    SciTech Connect

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  8. High-power picosecond laser pulse recirculation.

    PubMed

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J

    2010-07-01

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  9. High-power picosecond laser pulse recirculation.

    PubMed

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J

    2010-07-01

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses. PMID:20596201

  10. A picosecond high pressure gas switch

    SciTech Connect

    Cravey, W.R.; Poulsen, P.P.; Pincosy, P.A.

    1992-06-01

    Work is being done to develop a high pressure gas switch (HPGS) with picosecond risetimes for UWB applications. Pulse risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at high pressures and higher electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With these high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized on the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with lab data.

  11. A study of the proteorhodopsin primary photoreaction by low-temperature FTIR difference and ultrafast transient infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Amsden, Jason J.

    Proteorhodopsin (PR), a newly discovered microbial rhodopsin found in marine proteobacteria, functions as a light-driven proton pump similar to bacteriorhodopsin (BR). PR-containing bacteria account for ˜13% of the microorganisms in the oceans' photic zone and are responsible for a significant fraction of the biosphere's solar energy conversion. We study the initial response of proteorhodopsin to photon absorption using a combination of low-temperature (80 K) Fourier transform infrared (FTIR) difference spectroscopy and ultrafast transient infrared (TIR) spectroscopy. Low-temperature FTIR difference spectroscopy combined with site-directed mutagenesis and isotope labeling is used to detect and characterize changes occurring in the conformation of the retinal chromophore, protein, and internal water molecules of green-absorbing PR (GPR) and blue-absorbing PR (BPR) during the initial phototransition. Measurements on cryogenically trapped intermediates do not accurately reflect all native structural changes occurring in PR and other microbial rhodopsins on ultrafast time scales at room temperature. Recent studies demonstrate that photoactive proteins such as photoactive yellow protein, myoglobin, and green-fluorescent protein, can react within several picoseconds to photon absorption by their chromophores. Faster subpicosecond protein responses have been suggested to occur in rhodopsin-like proteins where retinal chromophore photoisomerization may impulsively drive structural changes in nearby protein groups. Here, I test this possibility by investigating the earliest protein and chromophore structural changes occurring in GPR using ultrafast TIR spectroscopy with ˜200 fs time resolution combined with non-perturbing isotope labeling. On the basis of total-15N and retinal C15D (retinal with a deuterium on carbon 15) isotope labeling, the all-trans to 13-cis retinal chromophore isomerization occurs with a 500-700 fs time constant and the amide II mode of one or more

  12. Functional near-infrared spectroscopy studies in children

    PubMed Central

    2012-01-01

    Psychosomatic and developmental behavioral medicine in pediatrics has been the subject of significant recent attention, with infants, school-age children, and adolescents frequently presenting with psychosomatic, behavioral, and psychiatric symptoms. These may be a consequence of insecurity of attachment, reduced self-confidence, and peer -relationship conflicts during their developmental stages. Developmental cognitive neuroscience has revealed significant associations between specific brain lesions and particular cognitive dysfunctions. Thus, identifying the biological deficits underlying such cognitive dysfunction may provide new insights into therapeutic prospects for the management of those symptoms in children. Recent advances in noninvasive neuroimaging techniques, and especially functional near-infrared spectroscopy (NIRS), have contributed significant findings to the field of developmental cognitive neuroscience in pediatrics. We present here a comprehensive review of functional NIRS studies of children who have developed normally and of children with psychosomatic and behavioral disorders. PMID:22433235

  13. Raman and infrared spectroscopic study of kamphaugite-(Y)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo

    2015-05-01

    We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH)·H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm-1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed.

  14. Infrared spectroscopy of molecules with nanorod arrays: a numerical study.

    PubMed

    Tardieu, Clément; Vincent, Grégory; Haïdar, Riad; Collin, Stéphane

    2016-04-15

    Nanorod arrays with diameters much smaller than the wavelength exhibit sharp resonances with strong electric-field enhancement and angular dependence. They are investigated for enhanced infrared spectroscopy of molecular bonds. The molecule 3-cyanopropyldimethylchlorosilane (CS) is taken as a reference, and its complex permittivity is determined experimentally in the 3-5 μm wavelength range. When grafted on silicon nitride nanorods, we show numerically that its weak absorption bands due to chemical bond vibrations can be enhanced by several orders of magnitude compared with unstructured thin film. We propose a figure of merit (FoM) to assess the performance of this spectroscopic scheme, and we study the impact of the nanorod cross section on the FoM.

  15. Ultrafast infrared studies of complex ligand rearrangements in solution

    SciTech Connect

    Payne, Christine K.

    2003-05-31

    The complete description of a chemical reaction in solution depends upon an understanding of the reactive molecule as well as its interactions with the surrounding solvent molecules. Using ultrafast infrared spectroscopy it is possible to observe both the solute-solvent interactions and the rearrangement steps which determine the overall course of a chemical reaction. The topics addressed in these studies focus on reaction mechanisms which require the rearrangement of complex ligands and the spectroscopic techniques necessary for the determination of these mechanisms. Ligand rearrangement is studied by considering two different reaction mechanisms for which the rearrangement of a complex ligand constitutes the most important step of the reaction. The first system concerns the rearrangement of a cyclopentadienyl ring as the response of an organometallic complex to a loss of electron density. This mechanism, commonly referred to as ''ring slip'', is frequently cited to explain reaction mechanisms. However, the ring slipped intermediate is too short-lived to be observed using conventional methods. Using a combination of ultrafast infrared spectroscopy and electronic structure calculations it has been shown that the intermediate exists, but does not form an eighteen-electron intermediate as suggested by traditional molecular orbital models. The second example examines the initial steps of alkyne polymerization. Group 6 (Cr, Mo, W) pentacarbonyl species are generated photolytically and used to catalyze the polymerization of unsaturated hydrocarbons through a series of coordination and rearrangement steps. Observing this reaction on the femto- to millisecond timescale indicates that the initial coordination of an alkyne solvent molecule to the metal center results in a stable intermediate that does not rearrange to form the polymer precursor. This suggests that polymerization requires the dissociation of additional carbonyl ligands before rearrangement can occur. Overall

  16. Crosstalk study of near infrared InGaAs detectors

    NASA Astrophysics Data System (ADS)

    Li, Xue; Tang, Hengjing; Li, Tao; Fan, Cui; Shao, Xiumei; Li, Jianwei; Wei, Jun; Gong, Haimei

    2016-05-01

    Crosstalk characteristics of high density FPA detectors attract widespread attention in the application of electro-optical systems. Crosstalk characteristics of near-infrared (NIR) InGaAs photodiodes and focal plane arrays (FPAs) were studied in this paper. The mesa type detector was investigated by using laser beam induced current technique (LBIC) to measure the absorption outside the designed photosensitive area, and the results show that the excess absorption enlarges the crosstalk of the adjacent pixels. The structure optimization using the effective absorption layer between the pixels can effectively reduce the crosstalk to 2.5%. The major crosstalk components of the optimization photodiode come from the electronic signal caused by carrier lateral diffusion. For the planar type detectors, test structures were used to compare the crosstalk of different structures, and the guard ring structure shows good suppression of the crosstalk. Then the back-illuminated 32x32 InGaAs photodiodes with 30μm pitch were designed, and LBIC was used to measure its lateral diffusion of the effective carriers and fill factor of photosensitive area. The results indicate that the fill factor of detectors can reach up to 98% when the diffusion region is optimized, and the minimum response exists between two neighborhood pixels. Based on these crosstalk measurement results and optimizing structure designs, the linear InGaAs photodiodes were designed and thus the InGaAs FPA assembly was fabricated. The assembly shows higher electro-optical performance and good improvement on crosstalk. The assembly was applied in infrared imaging system and modulation transfer function (MTF) of FPA assembly was calculated to be above 0.50. The clear image based on FPA assembly was obtained.

  17. Near-infrared laser delivery of nanoparticles to developing embryos: a study of efficacy and viability.

    PubMed

    Umanzor-Alvarez, Jose; Wade, Emily C; Gifford, Aliya; Nontapot, Kankowan; Cruz-Reese, Ariana; Gotoh, Tetsuya; Sible, Jill C; Khodaparast, Giti A

    2011-05-01

    Targeted delivery of materials to individual cells remains a challenge in nanoscience and nanomedicine. Near infrared (NIR) laser injection may be a promising alternative to manual injection (where the micropipet diameter limits targeting to small cells) or other laser techniques (such as picosecond green and UV lasers, which can be damaging to cells). However, the efficiency with which NIR pulses can deliver nanoparticles and any adverse effects on living cells needs thorough testing. Toward this end, we have determined the efficacy and toxicity of delivering quantum dots (QDs) into cells of Xenopus laevis embryos by NIR laser injection. Because this model system provides not only living cells but also a developing organism, we were able to assess relatively long-term effects of NIR pulses on embryonic development (through the tadpole stage). We developed parameters for NIR pulses that did not affect embryonic viability or morphology and delivered QDs as effectively as manual injection. Higher intensities of NIR pulses caused permanent damage to the targeted cells, and thus NIR pulses may also prove useful for ablation of specific cells within tissues.

  18. Near-infrared laser delivery of nanoparticles to developing embryos: a study of efficacy and viability.

    PubMed

    Umanzor-Alvarez, Jose; Wade, Emily C; Gifford, Aliya; Nontapot, Kankowan; Cruz-Reese, Ariana; Gotoh, Tetsuya; Sible, Jill C; Khodaparast, Giti A

    2011-05-01

    Targeted delivery of materials to individual cells remains a challenge in nanoscience and nanomedicine. Near infrared (NIR) laser injection may be a promising alternative to manual injection (where the micropipet diameter limits targeting to small cells) or other laser techniques (such as picosecond green and UV lasers, which can be damaging to cells). However, the efficiency with which NIR pulses can deliver nanoparticles and any adverse effects on living cells needs thorough testing. Toward this end, we have determined the efficacy and toxicity of delivering quantum dots (QDs) into cells of Xenopus laevis embryos by NIR laser injection. Because this model system provides not only living cells but also a developing organism, we were able to assess relatively long-term effects of NIR pulses on embryonic development (through the tadpole stage). We developed parameters for NIR pulses that did not affect embryonic viability or morphology and delivered QDs as effectively as manual injection. Higher intensities of NIR pulses caused permanent damage to the targeted cells, and thus NIR pulses may also prove useful for ablation of specific cells within tissues. PMID:21381199

  19. Humidity-dependent dynamic infrared linear dichroism study of a poly(ester urethane).

    PubMed

    Schoonover, Jon R; Steckle, Warren P; Cox, Jonathan D; Johnston, Cliff T; Wang, Yanqia; Gillikin, Angela M; Palmer, Richard A

    2007-05-01

    Fourier transform infrared techniques, infrared difference spectroscopy and dynamic infrared linear dichroism (DIRLD), have been utilized to explore the effects of humidity and water absorption on a poly(ester urethane). An environmental infrared microbalance cell was used to measure the infrared spectra as a function of humidity and accompanying weight change for the absorption-desorption processes. The infrared difference data indicate that exposure to humidity affects the hydrogen-bonding interactions in the polymer. Dynamic infrared linear dichroism studies in tensile deformation mode as a function of humidity demonstrate how changes in water content affect the orientational response of functional groups. Complex behavior as a function of humidity for functional groups involved in hydrogen bonding indicates that water absorbed by the polymer affects the micro-environments near these functional groups.

  20. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle.

    PubMed

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  1. Picosecond and subpicosecond visible laser ablation of optically transparent polymers

    NASA Astrophysics Data System (ADS)

    Serafetinides, A. A.; Skordoulis, C. D.; Makropoulou, M. I.; Kar, A. K.

    1998-09-01

    The ablation rates, as a function of the laser fluence, of the optically transparent polymers, Nylon-6,6 and PMMA, are reported using picosecond and subpicosecond laser pulses, obtained from a Regenerative Amplified Nd:YAG laser system. The laser pulses had a duration of 100 ps at 1064 and 532 nm wavelengths and 0.8 ps at 595 nm. The ablation rate results indicate a strong saturation behaviour for both polymers in the investigated irradiation conditions. The material removal is 2-3 times higher in the case of the visible (532 nm) picosecond laser ablation experiments. The surface topology of the polymers was also studied. The obtained Atomic Force Microscopy images reveal no mechanical damage in the inner ablation crater wall. The qualitative analysis of the ablation mechanism for ultrashort pulse laser irradiation reveals a combination of photochemically induced direct bond dissociation and a photothermal process due to the relaxation of the excited polymers within the vibrational levels of the ground state.

  2. Picosecond and femtosecond laser ablation of hard tissues

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexander A.; Makropoulou, Mersini I.; Kar, Ajoy K.; Khabbaz, Marouan

    1996-12-01

    In this study, the interaction of picosecond and femtosecond pulsed laser radiation with human dental tissue was investigated experimentally, as this unexplored field is expected to be a potential alternative in powerful laser processing of biomedical structures. Dentin ablation rate experiments were performed by using teeth sections of different thickness. Dental tissue samples were irradiated in air with i) a regenerative amplifier laser at 1064 nm, pulse duration 110 ps, ii) the second harmonic laser at 532 nm, pulse duration 100 ps, and iii) a picosecond tunable dye amplifier at 595 nm, pulse width 800 fs. In all the experiments the pulse repetition rate was 10 Hz. The ablation rate per pulse at different energy fluence settings was calculated by measuring the time needed for the perforation of the whole dental sample thickness. Short laser pulses can confine thermal energy within the optical zone, which maximizes photothermal and photomechanical mechanisms of interaction. Tissue ablation rates were found to be comparable to or better than other nanosecond lasers, and left smooth surfaces, free of thermal damage.

  3. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    PubMed Central

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  4. Subpicosecond and picosecond laser ablation of dental enamel: comparative analysis

    NASA Astrophysics Data System (ADS)

    Rode, Andrei V.; Madsen, Nathan R.; Kolev, Vesselin Z.; Gamaly, Eugene G.; Luther-Davies, Barry; Dawes, Judith M.; Chan, A.

    2004-06-01

    We report the use of sub-picosecond near-IR and ps UV pulsed lasers for precision ablation of freshly extracted human teeth. The sub-picosecond laser wavelength was ~800nm, with pulsewidth 150 fs and pulse repetition rate of 1kHz; the UV laser produced 10 ps pulses at 266 nm with pulse rate of ~1.2x105 pulses/s; both lasers produced ~1 W of output energy, and the laser fluence was kept at the same level of 10-25 J/cm2. Laser radiation from both laser were effectively absorbed in the teeth enamel, but the mechanisms of absorption were radically different: the near-IR laser energy was absorbed in a plasma layer formed through the optical breakdown mechanism initiated by multiphoton absorption, while the UV-radiation was absorbed due to molecular photodissociation of the enamel and conventional thermal deposition. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain low with subpicosecond laser pulses, but risen up to 30°C, well above the 5°C pain level with the UV-laser. This study demonstrates the potential for ultra-short-pulsed lasers to precision and painless ablation of dental enamel, and indicated the optimal combination of laser parameters in terms of pulse energy, duration, intensity, and repetition rate, required for the laser ablation rates comparable to that of mechanical drill.

  5. Protein stabilization by osmolytes from hyperthermophiles: effect of mannosylglycerate on the thermal unfolding of recombinant nuclease a from Staphylococcus aureus studied by picosecond time-resolved fluorescence and calorimetry.

    PubMed

    Faria, Tiago Q; Lima, João C; Bastos, Margarida; Maçanita, António L; Santos, Helena

    2004-11-19

    2-O-alpha-Mannosylglycerate, a negatively charged osmolyte widely distributed among (hyper)thermophilic microorganisms, is known to provide notable protection to proteins against thermal denaturation. To study the mechanism responsible for protein stabilization, pico-second time-resolved fluorescence spectroscopy was used to characterize the thermal unfolding of a model protein, Staphylococcus aureus recombinant nuclease A (SNase), in the presence or absence of mannosylglycerate. The fluorescence decay times are signatures of the protein state, and the pre-exponential coefficients are used to evaluate the molar fractions of the folded and unfolded states. Hence, direct determination of equilibrium constants of unfolding from molar fractions was carried out. Van't Hoff plots of the equilibrium constants provided reliable thermodynamic data for SNase unfolding. Differential scanning calorimetry was used to validate this thermodynamic analysis. The presence of 0.5 m potassium mannosylglycerate caused an increase of 7 degrees C in the SNase melting temperature and a 2-fold increase in the unfolding heat capacity. Despite the considerable degree of stabilization rendered by this solute, the nature and population of protein states along unfolding were not altered in the presence of mannosylglycerate, denoting that the unfolding pathway of SNase was unaffected. The stabilization of SNase by mannosylglycerate arises from decreased unfolding entropy up to 65 degrees C and from an enthalpy increase above this temperature. In molecular terms, stabilization is interpreted as resulting from destabilization of the denatured state caused by preferential exclusion of the solute from the protein hydration shell upon unfolding, and stabilization of the native state by specific interactions. The physiological significance of charged solutes in hyperthermophiles is discussed.

  6. Amplitude and polarization instability of picosecond light pulses exciting a semiconductor optical resonator.

    PubMed

    Markarov, V A; Pershin, S M; Podshivalov, A A; Zadoian, R S; Zheludev, N I

    1983-11-01

    The first results of our study of nonlinear shift, distortion of form, and destruction of picosecond light pulses interacting with a nonlinear Fabry-Perot resonator in a strongly nonstationary regime are reported. Polarization instability of the light pulse transmitted through a nonlinear resonator has been observed. PMID:19718182

  7. Tuneable Heterodyne Infrared Spectrometer for atmospheric and astronomical studies.

    PubMed

    Sonnabend, Guido; Wirtz, Daniel; Schmülling, Frank; Schieder, Rudolf

    2002-05-20

    The transportable setup of the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) is presented. Frequency tuneability over a wide range provided by the use of tuneable diode lasers as local oscillators (LO) allows a variety of molecules in the mid-infrared to be observed. Longtime integration, which is essential for astronomical observations, is possible owing to tight frequency control of the LO with optical feedback from an external cavity. THIS is developed to fly on the Stratospheric Observatory for Infrared Astronomy beginning in 2006 but can also be used on different types of ground-based telescopes.

  8. Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

    SciTech Connect

    Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

    2013-12-02

    We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes.

  9. Study of laser reflection of infrared cameras with germanium optics

    NASA Astrophysics Data System (ADS)

    Chiu, Patrio; Shih, Ishiang; Shi, S.; Laou, Philips

    2003-09-01

    Infrared cameras are widely used in today's battlefield for surveillance purpose. Because of retroreflection, an incident laser beam entering the camera optics results in a beam reflecting back to the direction of the laser source. An IR detector positioned close to the laser source can then detect the reflected beam. This effect can reveal the location of the cameras and thus increases the risk of covert operations. In the present work, the characteristics of the retroreflection is studied. It is found that the reflection intensity is high when the incident beam enters through the middle part of the lenses while it is low and the beam is diverged when entering through the outer part of the lenses. The reflection is symmetric when the incident beam is normal to the lenses while asymmetric when it is incident with an angle to the lenses. In order to study the potential effects on retroreflection of modified camera optics, IR low index slides (ZnSe and KCl with refractive indices of 2.49 and 1.54, respectively) with different thicknesses (2mm, 4mm and 6mm) are placed in the optical system. The result shows that the focal point of the lenses is changed by the addition of the slide but the optical paths of the reflection remain unchanged. The relationship between the different slides and beam intensity is also studied.

  10. GIRL: German Infrared Laboratory. Telescope study, phase B

    NASA Technical Reports Server (NTRS)

    Schlegelmilch, R.; Zeiss, C.

    1981-01-01

    The construction and mounting of mirrors for an infrared telescope are described. Tests conducted to determine the thermal and stress characteristics of various types of mounting for main and collection mirrors are also discussed.

  11. Dynamical test of Davydov-type solitons in acetanilide using a picosecond free-electron laser

    NASA Astrophysics Data System (ADS)

    Fann, Wunshain; Rothberg, Lewis; Roberson, Mark; Benson, Steve; Madey, John; Etemad, Shahab; Austin, Robert

    1990-01-01

    Picosecond infrared excitation experiments on acetanilide, an α-helix protein analog, indicate that the anomalous 1650-cm-1 band which appears on cooling of acetanilide crystals persists for at least several microseconds following rapid pulsed heating. The ground-state recovery time is 15+/-5 psec, consistent with a conventional mode strongly coupled to the phonon bath. We therefore suggest that the unusual temperature-dependent spectroscopy of acetanilide can be accounted for by slightly nondegenerate hydrogen atom configurations in the crystal.

  12. Towards microfluidic reactors for in situ synchrotron infrared studies

    NASA Astrophysics Data System (ADS)

    Silverwood, I. P.; Al-Rifai, N.; Cao, E.; Nelson, D. J.; Chutia, A.; Wells, P. P.; Nolan, S. P.; Frogley, M. D.; Cinque, G.; Gavriilidis, A.; Catlow, C. R. A.

    2016-02-01

    Anodically bonded etched silicon microfluidic devices that allow infrared spectroscopic measurement of solutions are reported. These extend spatially well-resolved in situ infrared measurement to higher temperatures and pressures than previously reported, making them useful for effectively time-resolved measurement of realistic catalytic processes. A data processing technique necessary for the mitigation of interference fringes caused by multiple reflections of the probe beam is also described.

  13. The application of near infrared spectroscopy in nutritional intervention studies

    PubMed Central

    Jackson, Philippa A.; Kennedy, David O.

    2013-01-01

    Functional near infrared spectroscopy (NIRS) is a non-invasive optical imaging technique used to monitor cerebral blood flow (CBF) and by proxy neuronal activation. The use of NIRS in nutritional intervention studies is a relatively novel application of this technique, with only a small, but growing, number of trials published to date. These trials—in which the effects on CBF following administration of dietary components such as caffeine, polyphenols and omega-3 polyunsaturated fatty acids are assessed—have successfully demonstrated NIRS as a sensitive measure of change in hemodynamic response during cognitive tasks in both acute and chronic treatment intervention paradigms. The existent research in this area has been limited by the constraints of the technique itself however advancements in the measurement technology, paired with studies endeavoring increased sophistication in number and locations of channels over the head should render the use of NIRS in nutritional interventions particularly valuable in advancing our understanding of the effects of nutrients and dietary components on the brain. PMID:23964231

  14. Radiometric Study of Soil Profiles in the Infrared Band

    NASA Astrophysics Data System (ADS)

    Ponomareva, T. V.; Ponomarev, E. I.

    2016-02-01

    The applicability of radiometric survey of soil profiles in the infrared range for the analysis of soil physical properties was studied. Radiometric data were obtained for different dates of the growing season for a number of soil profiles. The specificity of temperature profiles of texture-differentiated soils (Luvisols and Retisols) as related to weather conditions of the growing season was examined. The correlation analysis showed a close relationship between the air and surface soil temperatures and between the radiometric and thermodynamic soil temperatures in the upper 10 cm. In the studied profiles, the gradient of radiometric temperatures reached 0.5-0.8°C/cm in the humus horizons and sharply decreased at the depth of more than 15-20 cm. The gradient analysis of radiometric images made it possible to outline the boundaries of soil horizons. For the texture-differentiated soils, the most distinct boundaries were established between the gray-humus AY horizon and the underlying eluvial EL horizon in podzolic soils and between the AY horizon and the underlying humus-eluvial AEL horizon in gray soils.

  15. Design study of a laser-cooled infrared sensor

    NASA Astrophysics Data System (ADS)

    Hehlen, Markus P.; Boncher, William L.; Love, Steven P.

    2015-03-01

    The performance of a solid-state optical refrigerator is the result of a complex interplay of numerous optical and thermal parameters. We present a first preliminary study of an optical cryocooler using ray-tracing techniques. A numerical optimization identified a non-resonant cavity with astigmatism. This geometry offered more efficient pump absorption by the YLF:10%Yb laser-cooling crystal compared to non-resonant cavities without astigmatism that have been pursued experimentally so far. Ray tracing simulations indicate that ~80% of the incident pump light can absorbed for temperatures down to ~100 K. Calculations of heat loads, cooling power, and net payload heat lift are presented. They show that it is possible to cool a payload to a range of 90-100 K while producing a net payload heat lift of 80 mW and 300 mW when pumping a YLF:10%Yb crystal with 20 W and 50 W at 1020 nm, respectively. This performance is suited to cool HgCdTe infrared detectors that are used for sensing in the 8-12 μm atmospheric window. While the detector noise would be ~6× greater at 100 K than at 77 K, the laser refrigerator would introduce no vibrations and thus eliminate sources of microphonic noise that are limiting the performance of current systems.

  16. Design study of a laser-cooled infrared sensor

    SciTech Connect

    Hehlen, Markus Peter; Boncher, William Lawrence; Love, Steven Paul

    2015-03-10

    The performance of a solid-state optical refrigerator is the result of a complex interplay of numerous optical and thermal parameters. We present a first preliminary study of an optical cryocooler using ray-tracing techniques. A numerical optimization identified a non-resonant cavity with astigmatism. This geometry offered more efficient pump absorption by the YLF:10%Yb laser-cooling crystal compared to non-resonant cavities without astigmatism that have been pursued experimentally so far. Ray tracing simulations indicate that ~80% of the incident pump light can absorbed for temperatures down to ~100 K. Calculations of heat loads, cooling power, and net payload heat lift are presented. They show that it is possible to cool a payload to a range of 90–100 K while producing a net payload heat lift of 80 mW and 300 mW when pumping a YLF:10%Yb crystal with 20 W and 50 W at 1020 nm, respectively. This performance is suited to cool HgCdTe infrared detectors that are used for sensing in the 8–12 μm atmospheric window. While the detector noise would be ~6× greater at 100 K than at 77 K, the laser refrigerator would introduce no vibrations and thus eliminate sources of microphonic noise that are limiting the performance of current systems.

  17. Design study of a laser-cooled infrared sensor

    DOE PAGESBeta

    Hehlen, Markus Peter; Boncher, William Lawrence; Love, Steven Paul

    2015-03-10

    The performance of a solid-state optical refrigerator is the result of a complex interplay of numerous optical and thermal parameters. We present a first preliminary study of an optical cryocooler using ray-tracing techniques. A numerical optimization identified a non-resonant cavity with astigmatism. This geometry offered more efficient pump absorption by the YLF:10%Yb laser-cooling crystal compared to non-resonant cavities without astigmatism that have been pursued experimentally so far. Ray tracing simulations indicate that ~80% of the incident pump light can absorbed for temperatures down to ~100 K. Calculations of heat loads, cooling power, and net payload heat lift are presented. Theymore » show that it is possible to cool a payload to a range of 90–100 K while producing a net payload heat lift of 80 mW and 300 mW when pumping a YLF:10%Yb crystal with 20 W and 50 W at 1020 nm, respectively. This performance is suited to cool HgCdTe infrared detectors that are used for sensing in the 8–12 μm atmospheric window. While the detector noise would be ~6× greater at 100 K than at 77 K, the laser refrigerator would introduce no vibrations and thus eliminate sources of microphonic noise that are limiting the performance of current systems.« less

  18. Infrared thermometry study of nanofluid pool boiling phenomena

    PubMed Central

    2011-01-01

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement. PMID:21711754

  19. Infrared thermometry study of nanofluid pool boiling phenomena.

    PubMed

    Gerardi, Craig; Buongiorno, Jacopo; Hu, Lin-Wen; McKrell, Thomas

    2011-03-16

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

  20. Infrared thermometry study of nanofluid pool boiling phenomena

    NASA Astrophysics Data System (ADS)

    Gerardi, Craig; Buongiorno, Jacopo; Hu, Lin-Wen; McKrell, Thomas

    2011-12-01

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

  1. Infrared thermography based studies on mobile phone induced heating

    NASA Astrophysics Data System (ADS)

    Lahiri, B. B.; Bagavathiappan, S.; Soumya, C.; Jayakumar, T.; Philip, John

    2015-07-01

    Here, we report the skin temperature rise due to the absorption of radio frequency (RF) energy from three handheld mobile phones using infrared thermography technique. Experiments are performed under two different conditions, viz. when the mobile phones are placed in soft touch with the skin surface and away from the skin surface. Additionally, the temperature rise of mobile phones during charging, operation and simultaneous charging and talking are monitored under different exposure conditions. It is observed that the temperature of the cheek and ear regions monotonically increased with time during the usage of mobile phones and the magnitude of the temperature rise is higher for the mobile phone with higher specific absorption rate. The increase in skin temperature is higher when the mobile phones are in contact with the skin surface due to the combined effect of absorption of RF electromagnetic power and conductive heat transfer. The increase in the skin temperature in non-contact mode is found to be within the safety limit of 1 °C. The measured temperature rise is in good agreement with theoretical predictions. The empirical equation obtained from the temperature rise on the cheek region of the subjects correlates well with the specific absorption rate of the mobile phones. Our study suggests that the use of mobile phones in non-contact mode can significantly lower the skin temperature rise during its use and hence, is safer compared to the contact mode.

  2. Expansion dynamics of supercritical water probed by picosecond time-resolved photoelectron spectroscopy.

    PubMed

    Gladytz, Thomas; Abel, Bernd; Siefermann, Katrin R

    2015-02-21

    Vibrational excitation of liquid water with femtosecond laser pulses can create extreme states of water. Yet, the dynamics directly after initial sub-picosecond delocalization of molecular vibrations remain largely unclear. We study the ultrafast expansion dynamics of an accordingly prepared supercritical water phase with a picosecond time resolution. Our experimental setup combines vacuum-compatible liquid micro-jet technology and a table top High Harmonic light source driven by a femtosecond laser system. An ultrashort laser pulse centered at a wavelength of 2900 nm excites the OH-stretch vibration of water molecules in the liquid. The deposited energy corresponds to a supercritical phase with a temperature of about 1000 K and a pressure of more than 1 GPa. We use a time-delayed extreme ultraviolet pulse centered at 38.6 eV, and obtained via High Harmonic generation (HHG), to record valence band photoelectron spectra of the expanding water sample. The series of photoelectron spectra is analyzed with noise-corrected target transform fitting (cTTF), a specifically developed multivariate method. Together with a simple fluid dynamics simulation, the following picture emerges: when a supercritical phase of water expands into vacuum, temperature and density of the first few nanometers of the expanding phase drop below the critical values within a few picoseconds. This results in a supersaturated phase, in which condensation seeds form and grow from small clusters to large clusters on a 100 picosecond timescale.

  3. Picosecond laser ablation of porcine sclera

    NASA Astrophysics Data System (ADS)

    Góra, Wojciech S.; Harvey, Eleanor M.; Dhillon, Baljean; Parson, Simon H.; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    Lasers have been shown to be successful in certain medical procedures and they have been identified as potentially making a major contribution to the development of minimally invasive procedures. However, the uptake is not as widespread and there is scope for many other applications where laser devices may offer a significant advantage in comparison to the traditional surgical tools. The purpose of this research is to assess the potential of using a picosecond laser for minimally invasive laser sclerostomy. Experiments were carried out on porcine scleral samples due to the comparable properties to human tissue. Samples were prepared with a 5mm diameter trephine and were stored in lactated Ringer's solution. After laser machining, the samples were fixed in 3% glutaraldehyde, then dried and investigated under SEM. The laser used in the experiments is an industrial picosecond TRUMPF TruMicro laser operating at a wavelength of 1030nm, pulse length of 6ps, repetition rate of 1 kHz and a focused spot diameter of 30μm. The laser beam was scanned across the samples with the use of a galvanometer scan head and various ablation patterns were investigated. Processing parameters (pulse energy, spot and line separation) which allow for the most efficient laser ablation of scleral tissue without introducing any collateral damage were investigated. The potential to create various shapes, such as linear incisions, square cavities and circular cavities was demonstrated.

  4. Picosecond High Pressure Gas Switch experiment

    SciTech Connect

    Cravey, W.R.; Freytag, E.K.; Goerz, D.A.; Poulsen, P.; Pincosy, P.A.

    1993-08-01

    A high Pressure Gas Switch has been developed and tested at LLNL. Risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere pressures. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at higher pressures and electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With such high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized using the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with experimental data. Modifications made to the WASP HV pulser in order to drive the HPGS will also be discussed. Recovery times of less than 1 ms were recorded without gas flow in the switch chambers. Low pressure synthetic air was used as the switch dielectric. Longer recovery times were required when it was necessary to over-voltage the switch.

  5. IN SITU INFRARED STUDY OF CATALYTIC DECOMPOSITION OF NO

    SciTech Connect

    KHALID ALMUSAITEER; RAM KRISHNAMURTHY; STEVEN S.C. CHUANG

    1998-08-18

    The growing concerns for the environment and increasingly stringent standards for NO emission have presented a major challenge to control NO emissions from electric utility plants and automobiles. Catalytic decomposition of NO is the most attractive approach for the control of NO emission for its simplicity. Successful development of an effective catalyst for NO decomposition will greatly decrease the equipment and operation cost of NO control. Due to lack of understanding of the mechanism of NO decomposition, efforts on the search of an effective catalyst have been unsuccessful. Scientific development of an effective catalyst requires fundamental understanding of the nature of active site, the rate-limiting step, and an approach to prolong the life of the catalyst. Research is proposed to study the reactivity of adsorbates for the direct NO decomposition and to investigate the feasibility of two novel approaches for improving catalyst activity and resistance to sintering. The first approach is the use of silanation to stabilize metal crystallites and supports for Cu-ZSM-5 and promoted Pt catalysts; the second is utilization of oxygen spillover and desorption to enhance NO decomposition activity. An innovative infrared reactor system will be used to observe and determine the dynamic behavior and the reactivity of adsorbates during NO decomposition, oxygen spillover, and silanation. A series of experiments including X-ray diffraction, temperature programmed desorption, temperature programmed reaction, X-ray photoelectron spectroscopy will be used to characterized the catalysts. The information obtained from this study will provide a scientific basis for developing an effective catalyst for the NO decomposition under practical flue gas conditions.

  6. In Situ Infrared Study of Catalytic Decomposition of NO

    SciTech Connect

    Cher-Dip Tan; Steven S.C. Chuang

    1997-07-17

    The growing concerns for the environment and increasingly stringent standards for NO emission have presented a major challenge to control NO emmissions from electric utility plants and automobiles. Catalytic decomposition of NO is the most attractive approach for the control of NO emission for its simplicity. Successful development of an effective catalyst for NO decomposition will greatly decrease the equipment and operation cost of NO control. Due to lack of understanding of the mechanism of NO decomposition, efforts on the search of an effective catalyst have been unsuccesful. Scientific development of an effective catalyst requires fundamental understanding of the nature of active site, the rate-limiting step, and an approach to prolong the life of the catalyst. Research is proposed to study the reactivity of adsorbates for the direct NO decomposition and to investigate the feasibility of two novel approaches for improving catalyst activity and resistance to sintering. The first approach is the use of silanation to stabilize metal crystallites and supports for Cu-ZSM-5 and promoted Pt catalysts; the second is utilization of oxygen spillover and desorption to enhance NO decomposition activity. An innovative infrared reactor system will be used to observe and determine the dynamic behavior and the reactivity of adsorbates during NO decomposition, oxygen spillover, and silanation. A series of experiments including X-ray diffraction, temperature programmed desorption, temperature programmed reaction, X-ray photoelectron spectroscopy will be used to characterized the catalysts. The information obtained from this study will provide a scientific basis for developing an effective catalyst for the NO decomposition under practical flue gas conditions.

  7. Monolithic millimeter-wave and picosecond electronic technologies

    SciTech Connect

    Talley, W.K.; Luhmann, N.C.

    1996-03-12

    Theoretical and experimental studies into monolithic millimeter-wave and picosecond electronic technologies have been undertaken as a collaborative project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Coherent Millimeter-Wave Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. The work involves the design and fabrication of monolithic frequency multiplier, beam control, and imaging arrays for millimeter-wave imaging and radar, as well as the development of high speed nonlinear transmission lines for ultra-wideband radar imaging, time domain materials characterization and magnetic fusion plasma applications. In addition, the Coherent Millimeter-Wave Group is involved in the fabrication of a state-of-the-art X-band ({approximately}8-11 GHz) RF photoinjector source aimed at producing psec high brightness electron bunches for advanced accelerator and coherent radiation generation studies.

  8. Study on Senna alata and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Adiana, M. A.; Mazura, M. P.

    2011-04-01

    Senna alata L. commonly known as candle bush belongs to the family of Fabaceae and the plant has been reported to possess anti-inflammatory, analgesic, laxative and antiplatelet-aggregating activity. In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional infrared correlation spectroscopy (2D-IR) to study the main constituents of S. alata and its different extracts (extracted by hexane, dichloromethane, ethyl acetate and methanol in turn). The findings indicated that FT-IR and 2D-IR can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can identify the main chemical constituents in medicinal materials and their extracts, but also compare the components differences among similar samples. In a conclusion, FT-IR spectroscopy combined with 2D correlation analysis provides a powerful method for the quality control of traditional medicines.

  9. Infrared Spectroscopic Study for the Hydrated Clusters of Pentane Cation

    NASA Astrophysics Data System (ADS)

    Endo, Tomoya; Matsuda, Yoshiyuki; Fujii, Asuka

    2016-06-01

    We performed infrared predissociation spectroscopy of size-selected pentane-water cluster cations, [pentane-(H2O)n]+, n=1-3, generated through the vacuum-ultraviolet photoionization. In the infrared spectra of the di- and tri-hydrated clusters, there appear broad features which spread to the lower frequency region from 2800 cm-1. These broad features are assigned to vibrations of a proton, which is transferred from CH of the pentane cation to the water molecules. These results indicate that the pentane cation has high proton donor ability. We will discuss these results based on theoretical conputations.

  10. An infrared and luminescence study of tritiated amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Kosteski, T.; Kherani, N.P.; Gaspari, F.; Zukotynski, S.; Shmayda, W.

    1997-07-01

    Tritium has been incorporated into amorphous silicon. Infrared spectroscopy shows new infrared vibration modes due to silicon-tritium (Si-T) bonds in the amorphous silicon network. Si-T vibration frequencies are related to Si-H vibration frequencies by simple mass relationships. Inelastic collisions of {beta} particles, produced as a result of tritium decay, with the amorphous silicon network results in the generation of electron-hole pairs. Radiative recombination of these carriers is observed. Dangling bonds associated with the tritium decay reduce luminescence efficiency.

  11. Infrared laser sealing of porcine tissues: preliminary in vivo studies

    NASA Astrophysics Data System (ADS)

    Cilip, Christopher M.; Hutchens, Thomas C.; Kerr, Duane; Latimer, Cassandra; Rosenbury, Sarah B.; Giglio, Nicholas C.; Schweinsberger, Gino R.; Perkins, William C.; Wilson, Christopher R.; Ward, Arlen; Nau, William H.; Fried, Nathaniel M.

    2015-02-01

    We are exploring infrared (IR) lasers as an alternative energy modality to radiofrequency (RF) and ultrasonic (US) devices intended to provide rapid surgical hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1470-nm IR laser sealed and cut ex vivo porcine renal arteries of 1-8 mm in 2 s, yielding burst pressures < 1200 mmHg (compared to normal systolic blood pressure of 120 mmHg) and thermal coagulation zones < 3 mm (including the seal). This preliminary study describes in vivo testing of a laser probe in a porcine model. A prototype, fiber optic based handheld probe with vessel/tissue clasping mechanism was tested on blood vessels < 6 mm diameter using incident 1470-nm laser power of 35 W for 1-5 s. The probe was evaluated for hemostasis after sealing isolated and bundled vasculature of abdomen and hind leg, as well as liver and lung parenchyma. Sealed vessel samples were collected for histological analysis of lateral thermal damage. Hemostasis was achieved in 57 of 73 seals (78%). The probe consistently sealed vasculature in small bowel mesentery, mesometrium, and gastro splenic and epiploic regions. Seal performance was less consistent on hind leg vasculature including saphenous arteries and bundles and femoral and iliac arteries. Collagen denaturation averaged 1.6 mm in 8 samples excised for histologic examination. A handheld laser probe sealed porcine vessels in vivo. With further improvements in probe design and laser parameter optimization, IR lasers may provide an alternative to RF and US vessel sealing devices.

  12. A Satellite Infrared Technique for Diurnal Rainfall Variability Studies

    NASA Technical Reports Server (NTRS)

    Anagnostou, Emmanouil

    1998-01-01

    Reliable information on the distribution of precipitation at high temporal resolution (infrared (IR) brightness temperatures from geostationary platforms have a weak physical connection to precipitation, however, their high sampling frequency makes them attractive in studying the temporal evolution of cloudiness and convection. On the other hand, microwave-based (MW) observations from lower sampling-frequency polar-orbiting platforms can provide a better physical connection to precipitating hydrometeors. A recent invention in rainfall estimation from a combination of these two sensors involves adjustment of IR estimates using co-existing MW-based precipitation data on a monthly basis. These techniques use the MW data to remove systematic errors in IR rain estimates, while retaining the high sampling frequency of IR observations (approximately every 15-30 minutes). Perhaps of even greater importance to climate and hydrometeorological applications is the separation of mesoscale convective systems into a portion of rain associated with deep convection (hereafter called convective precipitation), and to precipitation falling from more widespread anvil clouds. This current work focuses on estimation of tropical convective and stratiform rainfall. We attempt to answer fundamental questions, such as : is estimation of convective and stratiform precipitation from IR feasible? If so, how accurate can this be? What is the scale dependence of the IR algorithm's performance? To address these questions, quantitative comparisons are performed between coincident IR- and MW-based instantaneous rainfall estimates at the MW 85 Ghz resolution (-12.5 km). Our data set spans a three-month period (January to March, 1996) of MW and IR observations over northern South America (15N-15S and 35W-80W), which includes the Amazon river basin.

  13. Fourier Transform Infrared Spectroscopic Studies Of Wheat In The Mid Infrared

    NASA Astrophysics Data System (ADS)

    Olinger, Jill M.; Griffiths, Peter R.

    1989-12-01

    Official grain standards of the United States state that wheat may be divided into seven classes which are: Durum, Red Durum, Hard Red Spring, Hard Red Winter, Soft Red Winter, White, and Mixed.1 Most end uses of wheat involve converting the grain into flour through one of a variety of grinding methods. The quality of wheat-based products is often very dependent upon the type or class of wheat which was used to make the flour. Pasta products, for example, are made almost exclusively from the flour of durum wheats, which are the hardest of the wheats listed above. The highest quality breads are produced using flour from wheats classed as hard, whereas cakes, cookies and pastries are considered best when flour from wheats classed as soft are used. It is obvious then that the capability of determining the class of a particular wheat, especially with respect to hardness, is of economic importance to growers, processors, and merchants of wheat and wheat products. Hardness has been measured in many different ways 2-5 but, as of yet, no one method has become the method of choice. This paper reports on the use of principal components analysis (PCA) of mid infrared diffuse reflectance (DR) spectra of diluted ground wheats to aid in the classification of those wheats with respect to their hardness. The theory and mathematics involved in a principal component analysis have been described elsewhere.9

  14. Preparation of thin polymer films for infrared reaction rate studies

    NASA Technical Reports Server (NTRS)

    Garrard, G. G.; Houston, D. W.

    1970-01-01

    Procedure for preparing thin films for infrared spectrophotometric analysis involves pressing of a neat mixture of reactants between nonreactive thin polymer films with noninterfering absorption bands. Pressing is done under a pressure that gives desirable thickness. Following this process, the film sandwich is cut to accommodate the laboratory instrument.

  15. Measuring picosecond isomerization kinetics via broadband microwave spectroscopy.

    PubMed

    Dian, Brian C; Brown, Gordon G; Douglass, Kevin O; Pate, Brooks H

    2008-05-16

    The rotational spectrum of a highly excited molecule is qualitatively different from its pure rotational spectrum and contains information about the intramolecular dynamics. We have developed a broadband Fourier transform microwave spectrometer that uses chirped-pulse excitation to measure a rotational spectrum in the 7.5- to 18.5-gigahertz range in a single shot and thereby reduces acquisition time sufficiently to couple molecular rotational spectroscopy with tunable laser excitation. After vibrationally exciting a single molecular conformation of cyclopropane carboxaldehyde above the barrier to C-C single-bond isomerization, we applied line-shape analysis of the dynamic rotational spectrum to reveal a product yield and picosecond reaction rate that were significantly different from statistical predictions. The technique should be widely applicable to dynamical studies of radical intermediates, molecular complexes, and conformationally flexible molecules with biological interest.

  16. Picosecond Acoustic Measurement of Anisotropic Properties of Thin Films

    SciTech Connect

    Perton, M.; Rossignol, C.; Chigarev, N.; Audoin, B.

    2007-03-21

    Properties of thin metallic films have been studied extensively by means of laser-picosecond ultrasonics. Generation of longitudinal and shear waves via thermoelastic mechanism and large source has been only demonstrated for waves vectors along the normal to the interface. However, such measurements cannot provide complete information about elastic properties of films. As it has been already shown for nanosecond ultrasonics, the knowledge of group or phase velocities in several directions for sources with small lateral size allows determining the stiffness tensor coefficients of a sample. The experimental set-up was prepared to obtain the thinnest size for the source to achieve acoustic diffraction. The identification of the stiffness tensor components, based on the inversion of the bulk waves phase velocities, is applied to signals simulated and experimentally recorded for a material with hexagonal properties. First estimation of stiffness tensor coefficients for thin metallic film 2.1 {mu}m has been performed.

  17. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  18. Timing characteristics of Large Area Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Adams, B. W.; Elagin, A.; Frisch, H. J.; Obaid, R.; Oberla, E.; Vostrikov, A.; Wagner, R. G.; Wang, J.; Wetstein, M.

    2015-09-01

    The LAPPD Collaboration was formed to develop ultrafast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub-picosecond laser. We observe single-photoelectron time resolutions of a 20 cm × 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 μm, and median gains higher than 107. The RMS measured at one particular point on an LAPPD detector is 58 ps, with ± 1σ of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  19. High-intensity coherent FIR radiation from sub-picosecond electron bunches

    SciTech Connect

    Kung, P.H.; Lihn, Hung-chi; Wiedemann, H.; Bocek, D.

    1994-01-01

    A facility to generate high-intensity, ultra-short pulses of broad-band far-infrared radiation has been assembled and tested at Stanford. The device uses sub-picosecond relativistic electron bunches to generate coherent radiation through transition or synchrotron radiation in the far-infrared (FIR) regime between millimeter waves and wavelengths of about 100 {mu}m and less. Experimental results show a peak radiation power of greater than 0.33 MW within a micro-bunch and an average FIR radiation power of 4 mW. The average bunch length of 2856 micro-bunches within a 1 {mu}sec macro-pulse is estimated to be about 480 sec. Simulations experimental setup and results will be discussed.

  20. Joint microwave and infrared studies for soil moisture determination

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.; Schieldge, J. P.; Kahle, A. B. (Principal Investigator)

    1980-01-01

    The feasibility of using a combined microwave-thermal infrared system to determine soil moisture content is addressed. Of particular concern are bare soils. The theoretical basis for microwave emission from soils and the transport of heat and moisture in soils is presented. Also, a description is given of the results of two field experiments held during vernal months in the San Joaquin Valley of California.

  1. High Efficiency Near Infrared Spectrometer for Zodiacal Light Spectral Study

    NASA Technical Reports Server (NTRS)

    Kutyrea, A. S.

    2008-01-01

    We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 61 2, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I lneat 5 184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

  2. Study on the characteristics of different infrared transmission in atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Wang, Jing-yuan; Xu, Zhi-yong; Chang, Shuai; Zhao, Ji-yong; Chen, Yi-wang; Wang, Rong; Wei, Yi-mei

    2015-10-01

    It is known theoretically that the long wavelength infrared has better performance when transmitting in atmospheric turbulence. In order to evaluate the influence of the atmospheric turbulence quantificationally, the characteristics of different infrareds transmission in atmospheric turbulence are simulated and studied. A series of time relevant phase screens of atmospheric turbulence are simulated based on Fourier transform method proposed by McGlamery. Wind speed and direction are introduced in the meantime. Wavefront distortion, image spot dancing and spreading, receive loss of different wavelengths (0.85μm, 3.6μm, 10.6μm) are simulated respectively and compared to each other. The results show that the performances of long wavelength infrared (10.6μm) are the best, mid wavelength infrared (3.6μm) takes the second place and short wavelength infrared (0.85μm) is the worst.

  3. Infrared study of transitional disks in Ophiuchus with Herschel

    NASA Astrophysics Data System (ADS)

    Rebollido, Isabel; Merín, Bruno; Ribas, Álvaro; Bustamante, Ignacio; Bouy, Hervé; Riviere-Marichalar, Pablo; Prusti, Timo; Pilbratt, Göran L.; André, Philippe; Ábrahám, Péter

    2015-09-01

    Context. Observations of nearby star-forming regions with the Herschel Space Observatory complement our view of the protoplanetary disks in Ophiuchus with information about the outer disks. Aims: The main goal of this project is to provide new far-infrared fluxes for the known disks in the core region of Ophiuchus and to identify potential transitional disks using data from Herschel. Methods: We obtained PACS and SPIRE photometry of previously spectroscopically confirmed young stellar objects (YSO) in the region and analysed their spectral energy distributions. Results: From an initial sample of 261 objects with spectral types in Ophiuchus, we detect 49 disks in at least one Herschel band. We provide new far-infrared fluxes for these objects. One of them is clearly a new transitional disk candidate. Conclusions: The data from Herschel Space Observatory provides fluxes that complement previous infrared data and that we use to identify a new transitional disk candidate. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Final reduced Herschel maps are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/581/A30Appendix A is available in electronic form at http://www.aanda.orgAll tables are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/581/A30

  4. [Study on the soil mid-infrared photoacoustic spectroscopy].

    PubMed

    Du, Chang-wen; Zhou, Jian-min; Wang, Huo-yan; Zhang, Jia-bao; Zhu, An-ning

    2008-06-01

    Infrared photoacoustic spectroscopy (PAS) is a new style to obtain data based on photoacoustic theory. Photoacoustic thoeory is based on the absorption of electromagnetic radiation by analyte molecules, and the absorbed energy is measured by detecting pressure fluctuations in the form of sound waves or shock pulses. In contrast to conventional absorption spectroscopy, PAS allows the determination of absorption coefficients over several orders of magnitude, even in very black and strongly scattering soil samples. Red soil, fulvic soil and paddy soil were collected from Fengqiu National Ecological Experimental Station, Yingtan Red Soil Experimental Station, and Changshu Ecological Experimental Station, respectively. These soil samples were used as experimental materials to characterize the Fourier transform mid-infrared photoacoustic spectra (FTIR-PAS). Compared with infrared transmittance spectra and reflectance spectra, the testing of FTIR-PAS spectra was very fast and convenient without any pr-treatment, and there were more abundant absorptions as well as appropriate absorption values in the spectra; The main soil components (kaolin, bentonite, sand and CaCO3) also showed several strong absorptions with specific characteristics in the spectra; Further more, the interference of water with the PAS spectra was significantly smaller than that with reflectance spectra. Therefore, the soil properties could be better characterized by FTIR-PAS. The principal components analysis based on the FTIR-PAS spectra indicated that there were two main principal components (PCA1, PCA2) which contained 98.17% variance of the spectra, and the two-dimensionol distribution was made by plotting these two principal components to classify the soil type, and the results indicated that this distribution could be applied to distinguish soil type, which provided new technique for soil identification as well as further quantitative analysis in soil science.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  6. Study of infrared point source simulator for generating the multi-decoy

    NASA Astrophysics Data System (ADS)

    Zeng, Chang-e.; Yang, Di; Su, Jian-gang; Huang, Yan-jun; Wang, Zhi-sheng

    2013-08-01

    The hardware-in-loop test system for infrared point-type guide missile was introduced;The decoy irradiation and motion characteristics were analyzed; multi-decoy generation mode and principle were studied.

  7. Infrared Thermography Applied to the Study of Cultural Heritage

    NASA Astrophysics Data System (ADS)

    Mercuri, F.; Cicero, C.; Orazi, N.; Paoloni, S.; Marinelli, M.; Zammit, U.

    2015-06-01

    Active infrared thermography is an important non-destructive technique frequently employed in the analysis of cultural heritage. For its capability to show subsurface features in the artifacts, this technique has been used to investigate various kinds of artifacts, composed of different structures and materials. In this work, an overview of its recent applications is presented. In particular, the detection of cold working features in bronze sculpture investigations, of buried features in ancient book bindings, such as their structural characteristics and written scraps re-used in their manufacturing process, and on the investigation of defects and inhomogeneities in illuminations, is reported.

  8. Design study for Thermal Infrared Multispectral Scanner (TIMS)

    NASA Technical Reports Server (NTRS)

    Stanich, C. G.; Osterwisch, F. G.; Szeles, D. M.; Houtman, W. H.

    1981-01-01

    The feasibility of dividing the 8-12 micrometer thermal infrared wavelength region into six spectral bands by an airborne line scanner system was investigated. By combining an existing scanner design with a 6 band spectrometer, a system for the remote sensing of Earth resources was developed. The elements in the spectrometer include an off axis reflective collimator, a reflective diffraction grating, a triplet germanium imaging lens, a photoconductive mercury cadmium telluride sensor array, and the mechanical assembly to hold these parts and maintain their optical alignment across a broad temperature range. The existing scanner design was modified to accept the new spectrometer and two field filling thermal reference sources.

  9. The Far-Infrared Surveyor Mission study: paper I, the genesis

    NASA Astrophysics Data System (ADS)

    Meixner, M.; Cooray, A.; Carter, R.; DiPirro, M.; Flores, A.; Leisawitz, D.; Armus, L.; Battersby, C.; Bergin, E.; Bradford, C. M.; Ennico, K.; Melnick, G. J.; Milam, S.; Narayanan, D.; Pontoppidan, K.; Pope, A.; Roellig, T.; Sandstrom, K.; Su, K. Y. L.; Vieira, J.; Wright, E.; Zmuidzinas, J.; Alato, S.; Carey, S.; Gerin, M.; Helmich, F.; Menten, K.; Scott, D.; Sakon, I.; Vavrek, R.

    2016-07-01

    This paper describes the beginning of the Far-Infrared Surveyor mission study for NASA's Astrophysics Decadal 2020. We describe the scope of the study, and the open process approach of the Science and Technology Definition Team. We are currently developing the science cases and provide some preliminary highlights here. We note key areas for technological innovation and improvements necessary to make a Far-Infrared Surveyor mission a reality.

  10. Water dynamics in salt solutions studied with ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy.

    PubMed

    Fayer, Michael D; Moilanen, David E; Wong, Daryl; Rosenfeld, Daniel E; Fenn, Emily E; Park, Sungnam

    2009-09-15

    Water is ubiquitous in nature, but it exists as pure water infrequently. From the ocean to biology, water molecules interact with a wide variety of dissolved species. Many of these species are charged. In the ocean, water interacts with dissolved salts. In biological systems, water interacts with dissolved salts as well as charged amino acids, the zwitterionic head groups of membranes, and other biological groups that carry charges. Water plays a central role in a vast number of chemical processes because of its dynamic hydrogen-bond network. A water molecule can form up to four hydrogen bonds in an approximately tetrahedral arrangement. These hydrogen bonds are continually being broken, and new bonds are being formed on a picosecond time scale. The ability of the hydrogen-bond network of water to rapidly reconfigure enables water to accommodate and facilitate chemical processes. Therefore, the influence of charged species on water hydrogen-bond dynamics is important. Recent advances in ultrafast coherent infrared spectroscopy have greatly expanded our understanding of water dynamics. Two-dimensional infrared (2D IR) vibrational echo spectroscopy is providing new observables that yield direct information on the fast dynamics of molecules in their ground electronic state under thermal equilibrium conditions. The 2D IR vibrational echoes are akin to 2D nuclear magnetic resonance (NMR) but operate on time scales that are many orders of magnitude shorter. In a 2D IR vibrational echo experiment (see the Conspectus figure), three IR pulses are tuned to the vibrational frequency of interest, which in this case is the frequency of the hydroxyl stretching mode of water. The first two pulses "label" the initial molecular structures by their vibrational frequencies. The system evolves between pulses two and three, and the third pulse stimulates the emission of the vibrational echo pulse, which is the signal. The vibrational echo pulse is heterodyne, detected by combining it

  11. Infrared studies of galactic center x-ray sources

    NASA Astrophysics Data System (ADS)

    DeWitt, Curtis

    In this dissertation I use a variety of approaches to discover the nature of a subset of the nearly 10,000 X-ray point sources in the 2° x 0.8° region around the Galactic Center. I produced a JHK s source catalog of the 170 x170 region around Sgr A* an area containing 4339 of these X-ray sources, with the ISPI camera on the CTIO 4-m telescope. I cross-correlated the Chandra and ISPI catalogs to find potential near-infrared (NIR) counterparts to the X-ray sources. The extreme NIR source crowding in the field means that it is not possible to establish the authenticity of the matches with astrometry and photometry alone. I found 2137 IR/X-ray astrometrically matched sources; statistically I calculated that my catalog contains 289+/-13 true matches to soft X-ray sources and 154 +/- 39 matches to hard X-ray sources. However, the fraction of matches to hard sources that are spurious is 90%, compared to 40% for soft source matches, making the hard source NIR matches particularly challenging for spectroscopic follow-up. I statistically investigated the parameter space of matched sources and identified a set of 98 NIR matches to hard X-ray sources with reddenings consistent with the GC distance which have a 45% probability of being true counterparts. I created two additional photometric catalogs of the GC region to investigate the variability of X-ray counterparts over a time baseline of several years. I found 48 variable NIR sources matched to X-ray sources, with 2 spectroscopically confirmed to be true counterparts (1 in previous literature and one in this study). I took spectra of 46 of my best candidates for counterparts to X-ray sources toward the GC, and spectroscopically confirmed 4 sources as the authentic physical counterpart on the basis of emission lines in the H and K band spectra. These sources include a Be high mass X-ray binary located 16 pc in projection away from Sgr A*; a hard X-ray symbiotic binary located 22 pc in projection from Sgr A*; an O

  12. Development of near infrared spectrometer for gem materials study

    NASA Astrophysics Data System (ADS)

    Jindata, W.; Meesiri, W.; Wongkokua, W.

    2015-07-01

    Most of gem materials can be characterized by infrared absorption spectroscopy. Normally, mid infrared absorption technique has been applied for investigating fundamental vibrational modes. However, for some gem materials, such as tourmaline, NIR is a better choice due to differentiation. Most commercial NIR spectrometers employ complicated dispersive grating or Fourier transform techniques. In this work, we developed a filter type NIR spectrometer with the availability of high efficiency and low-cost narrow bandpass NIR interference filters to be taught in a physics laboratory. The instrument was designed for transmission-mode configuration. A 50W halogen lamp was used as NIR source. There were fourteen NIR filters mounted on a rotatory wheel for wavelength selection ranging from 1000-1650 nm with steps of 50 nm. A 1.0 mm diameter of InGaAs photodiode was used as the detector for the spectrometer. Hence, transparent gem materials can be used as samples for experiment. Student can learn vibrational absorption spectroscopy as well as Beer-Lambert law from the development of this instrument.

  13. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): A SOUNDING ROCKET PAYLOAD TO STUDY THE NEAR INFRARED EXTRAGALACTIC BACKGROUND LIGHT

    SciTech Connect

    Zemcov, M.; Bock, J.; Hristov, V.; Levenson, L. R.; Mason, P.; Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K.; Wada, T.; Battle, J.; Cooray, A.; Keating, B.; Renbarger, T.; Kim, M. G.; Lee, D. H.; Nam, U. W.; Sullivan, I.; Suzuki, K.

    2013-08-15

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recoverable and has flown four times, with modifications to the payload having been informed by analysis of the first flight data. All four instruments performed to specifications during the subsequent flights, and the scientific data from these flights are currently being analyzed.

  14. Feasibility study of electron transfer quantum well infrared photodetectors for spectral tuning in the long-wave infrared band

    SciTech Connect

    Jolley, Greg; Dehdashti Akhavan, Nima; Umana-Membreno, Gilberto; Antoszewski, Jarek; Faraone, Lorenzo

    2013-11-21

    An electron transfer quantum well infrared photodetector (QWIP) consisting of repeating units of two coupled quantum wells (QWs) is capable of exhibiting a two color voltage dependent spectral response. However, significant electron transfer between the coupled QWs is required for spectral tuning, which may require the application of relatively high electric fields. Also, the band structure of coupled quantum wells is more complicated in comparison to a regular quantum well and, therefore, it is not always obvious if an electron transfer QWIP can be designed such that it meets specific performance characteristics. This paper presents a feasibility study of the electron transfer QWIP and its suitability for spectral tuning. Self consistent calculations have been performed of the bandstructure and the electric field that results from electron population within the quantum wells, from which the optical characteristics have been obtained. The band structure, spectral response, and the resonant final state energy locations have been compared with standard QWIPs. It is shown that spectral tuning in the long-wave infrared band can be achieved over a wide wavelength range of several microns while maintaining a relatively narrow spectral response FWHM. However, the total absorption strength is more limited in comparison to a standard QWIP, since the higher QW doping densities require much higher electric fields for electron transfer.

  15. Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

    PubMed

    Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

    2016-01-01

    We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

  16. Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

    PubMed

    Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

    2016-01-01

    We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied. PMID:26696156

  17. A rheumatoid arthritis study by Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Carvalho, Carolina S.; Silva, Ana Carla A.; Santos, Tatiano J. P. S.; Martin, Airton A.; dos Santos Fernandes, Ana Célia; Andrade, Luís E.; Raniero, Leandro

    2012-01-01

    Rheumatoid arthritis is a systemic inflammatory disease of unknown causes and a new methods to identify it in early stages are needed. The main purpose of this work is the biochemical differentiation of sera between normal and RA patients, through the establishment of a statistical method that can be appropriately used for serological analysis. The human sera from 39 healthy donors and 39 rheumatics donors were collected and analyzed by Fourier Transform Infrared Spectroscopy. The results show significant spectral variations with p<0.05 in regions corresponding to protein, lipids and immunoglobulins. The technique of latex particles, coated with human IgG and monoclonal anti-CRP by indirect agglutination known as FR and CRP, was performed to confirm possible false-negative results within the groups, facilitating the statistical interpretation and validation of the technique.

  18. Infrared Photoablation Studies of Arsenic Selenide with the Vanderbilt FEL

    NASA Astrophysics Data System (ADS)

    Adair, Janet; Marka, Zsuzsanna; Albert, Mike; Singh, Shailesh; Tolk, Norman

    2000-03-01

    In recent years arsenic selenide has shown a high potential for application as an infrared fiber material. It transmits in most of the 2-10 micron region, which is available at the Vanderbilt Free Electron Laser (FEL). The ablation threshold was measured for the bulk material at several different wavelengths corresponding to impurity absorption, such as Se-H and C-H vibrational modes. Using a time of flight spectrometer to detect the ablated particles, individual As/Se ions as well as bigger clusters of 6 As/Se atoms were observed. The Vanderbilt FEL delivers 3-5 microsecond long macropulses which consist of 1 ps long micropulses separated by 350 ps. Previous threshold measurements were made with the entire length of the macropulse hitting the sample. In the future a Pockel cell will be used to reduce the length of the macropulse to investigate the pulse length dependence of the ablation process. (Work funded by ONR)

  19. An infrared study of Orion Molecular Cloud-2 (OMC-2)

    SciTech Connect

    Johnson, J.J.; Gehrz, R.D.; Jones, T.J.; Hackwell, J.A.; Grasdalen, G.L. The Aerospace Corp., Space Sciences Laboratory, Los Angeles, CA Wyoming Infrared Observatory, Laramie )

    1990-08-01

    This paper reports 1.2-23 micron photometry for 11 discrete sources in Orion Molecular Cloud-2 (OMC-2). These data, combined with H and K photometric and K polarimetric images, are used to model the cluster sources. Most appear to be young stars of roughly solar mass. Some have circumstellar dust reradiation or reflection nebulosity. A model based on single scattering of light from an exciting star explains some features of the IRS 1 nebula, the largest reflection nebula in OMC-2. However, the red colors and high surface brightness of the IRS 1 nebula require a cool excitation source that is more luminous than far-infrared observations would indicate. 34 refs.

  20. Infrared cameras are potential traceable "fixed points" for future thermometry studies.

    PubMed

    Yap Kannan, R; Keresztes, K; Hussain, S; Coats, T J; Bown, M J

    2015-01-01

    The National physical laboratory (NPL) requires "fixed points" whose temperatures have been established by the International Temperature Scale of 1990 (ITS 90) be used for device calibration. In practice, "near" blackbody radiators together with the standard platinum resistance thermometer is accepted as a standard. The aim of this study was to report the correlation and limits of agreement (LOA) of the thermal infrared camera and non-contact infrared temporal thermometer against each other and the "near" blackbody radiator. Temperature readings from an infrared thermography camera (FLIR T650sc) and a non-contact infrared temporal thermometer (Hubdic FS-700) were compared to a near blackbody (Hyperion R blackbody model 982) at 0.5 °C increments between 20-40 °C. At each increment, blackbody cavity temperature was confirmed with the platinum resistance thermometer. Measurements were taken initially with the thermal infrared camera followed by the infrared thermometer, with each device mounted in turn on a stand at a fixed distance of 20 cm and 5 cm from the blackbody aperture, respectively. The platinum thermometer under-estimated the blackbody temperature by 0.015 °C (95% LOA: -0.08 °C to 0.05 °C), in contrast to the thermal infrared camera and infrared thermometer which over-estimated the blackbody temperature by 0.16 °C (95% LOA: 0.03 °C to 0.28 °C) and 0.75 °C (95% LOA: -0.30 °C to 1.79 °C), respectively. Infrared thermometer over-estimates thermal infrared camera measurements by 0.6 °C (95% LOA: -0.46 °C to 1.65 °C). In conclusion, the thermal infrared camera is a potential temperature reference "fixed point" that could substitute mercury thermometers. However, further repeatability and reproducibility studies will be required with different models of thermal infrared cameras.

  1. A Picosecond 14.7 nm X-Ray Laser for Probing Matter Undergoing Rapid Changes

    SciTech Connect

    Dunn, J; Smith, R F; Nilsen, J; Nelson, A J; Van Buuren, T W; Moon, S J; Hunter, J R; Filevich, J; Rocca, J J; Marconi, M C; Shlyaptsev, V N

    2002-10-07

    With laser-driven tabletop x-ray lasers now operating in the efficient saturation regime, the source characteristics of high photon flux, high monochromaticity, picosecond pulse duration, and coherence are well-matched to many applications involving the probing of matter undergoing rapid changes. We give an overview of recent experiments at the Lawrence Livermore National Laboratory (LLNL) Compact Multipulse Terawatt (COMET) laser using the picosecond 14.7 nm x-ray laser as a compact, ultrafast probe for surface analysis and for interferometry of laser-produced plasmas. The plasma density measurements for known laser conditions allow us to reliably and precisely benchmark hydrodynamics codes. In the former case, the x-ray laser ejects photo-electrons, from the valence band or shallow core-levels of the material, and are measured in a time-of-flight analyzer. Therefore, the electronic structure can be studied directly to determine the physical properties of materials undergoing rapid phase changes.

  2. Amplification of Picosecond Pulses in a 140-GHz Gyrotron-Traveling Wave Tube

    PubMed Central

    Kim, H. J.; Nanni, E. A.; Shapiro, M. A.; Sirigiri, J. R.; Woskov, P. P.; Temkin, R. J.

    2011-01-01

    An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro-TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE06 mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing by the finite gain bandwidth of 1.2 GHz. Experimental results taken over a wide range of parameters show good agreement with a theoretical model in the small signal gain regime. These results show that in order to limit the pulse broadening effect in gyrotron amplifiers, it is crucial to both choose an operating frequency at least several percent above the cutoff of the waveguide circuit and operate at the center of the gain spectrum with sufficient gain bandwidth. PMID:21230783

  3. Tunable far infrared studies of molecular parameters in support of stratospheric measurements

    NASA Technical Reports Server (NTRS)

    Chance, Kelly V.; Evenson, K. M.; Park, K.; Radostitz, J. V.; Jennings, D. A.; Nolt, I. G.; Vanek, M. D.

    1991-01-01

    Lab studies were made in support of far infrared spectroscopy of the stratosphere using the Tunable Far InfraRed (TuFIR) method of ultrahigh resolution spectroscopy and, more recently, spectroscopic and retrieval calculations performed in support of satellite-based atmospheric measurement programs: the Global Ozone Monitoring Experiment (GOME), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY).

  4. Experimental studies of the far-infrared spectra of cosmic-type ices

    NASA Technical Reports Server (NTRS)

    Hudson, Reggie L.

    1992-01-01

    Work performed during the period is reported. The abstract of a paper presented at the Second International Workshop on the Nature of Cometary Organic Matter is included. Far infrared spectra of amorphous and crystalline water ice before and after proton irradiation is presented. Also, a study of clathrate hydrates was conducted in which a methanol (CH3OH) clathrate hydrate was prepared and its far-infrared spectrum investigated. This paper is also included.

  5. A Study of Thermal Infrared Field Spectral Signatures: Implications for Studies of Mars.

    NASA Astrophysics Data System (ADS)

    Keim, E.; Kirkland, L.; Herr, K.; Adams, P.; Hackwell, J.

    2000-10-01

    Hyperspectral data recorded of indurated, weathered carbonates by the airborne imaging spectrometer SEBASS show that some massive carbonates exhibit dramatically reduced spectral contrast for the strong carbonate bands at 6.5 and 11.25 microns. If massive carbonates are present on Mars, this type of reduced spectral contrast could explain why they have not been detected using thermal infrared data sets, including the Global Surveyor Thermal Emission Spectrometer (TES). It could also cause similarly rough carbonates to be missed by the planned 2001 nine-band radiometer THEMIS, and could affect measurements by a landed spectrometer. On the other hand, SEBASS data demonstrate that these deposits can be detected by spectra recorded with sufficient signal-to-noise ratio (SNR). The observed reduction in band contrast is significant, and we conclude it is cause by surface roughness effects [1]. The nature of carbonate and other formations on Mars is uncertain, but a rough surface is certainly a possibility that must be taken into account. These results should be considered in planning for future instruments and when utilizing current data sets to set detection limits. Most spectral studies to determine detection limits rely predominantly on laboratory measurements of well-crystalline, pure end-members, with desirable instrument parameters and detection limits based on those results. However, our results show the importance of extending thermal infrared spectral studies to the field, and the relevance to spectral studies of Mars. This effect was found by drawing on expertise and unique technology most commonly used for the Department of Defense (DoD). The significance of the lessons learned illustrate the importance both of extending spectral studies to the field, and of drawing on non-traditional groups in order to best define what is needed to detect and identify interesting materials on Mars using infrared spectroscopy. [1] Kirkland L. et al. (2000) LPSC abs.1876 and

  6. Photon number resolving in picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Blazej, Josef; Hamal, Karel

    2005-04-01

    We are reporting on research and development in the field of thin-layer planar silicon avalanche photodiodes operated as photon counters in a Geiger mode. We have developed and tested a technique, which permits an estimation of the photon number initiated a detection process. It can be applied in a time correlated photon counting experiment simultaneously with originally required time interval estimation. The principal limitation is a using of laser pulse with width below 30 ps to achieve detection concurrent in compare with carrier multiplication speed. The number of photons which triggered the avalanche is estimated on the basis of the effective rise-time difference of the avalanche current. The active quenching and gating circuit provides two uniform electrical pulses, and the time interval between them is related to the number of photons detected. The strong temporal correlation between avalanche start and one of pulses is preserved. Employing the picosecond event timing device, the photon number can be estimated within the dynamical range from 1 up to 1000 photons with the resolution better than a factor of three. The avalanche structure is operated on temperature achievable by thermo-electrical cooling. The applications of presented technique are in any time correlated photon counting (TCPC) measurement where the additional information about signal strength, i.e. statistical number of photons in laser pulse, is interesting. Other applications in the testing of quantum-well-based single photon light sources or squeezed light sources are expected.

  7. A new photometric study of Herbig Ae/Be stars in the infrared

    NASA Astrophysics Data System (ADS)

    Chen, P. S.; Shan, H. G.; Zhang, P.

    2016-04-01

    In this paper we collected almost all HAeBe stars known so far (253 sources in total) to photometrically study their infrared properties. The 2MASS, WISE, IRAS and AKARI data are employed to make analyses. It is shown from several two-color diagrams that from 1 μm to 60 μm infrared radiations from circumstellar disks with the power law distribution play a very important role for infrared excesses which are much larger than that for ordinary Be stars. In the WISE two-color diagram, (W2-W3) vs. (W1-W2), some sources show thermal emissions probably due to dust surrounded and enhanced PAH features at 3.3 and 11.3 μm. In the wavelength longer than 60 μm infrared radiations are not so influenced by the circumstellar disk, but mainly from the ISM surrounded.

  8. Infrared spectrometry studies: Spectral digital data acquisition system (1971 version)

    NASA Technical Reports Server (NTRS)

    Lu, L.; Lyon, R. J. P.

    1971-01-01

    The construction of the Stanford Spectral Digital Data Acquisition System is described. The objective of the system is to record both the spectral distribution of incoming radiation from the rock samples measured by the spectroradiometer (Exotech Model 10-34 Circular Variable Filter Infrared Spectroradiometer) together with other weather information. This system is designed for both laboratory and field measurement programs. The multichannel inputs (8 channels) of the system are as follows: Ch 1 the Spectro-radiometer, Ch 2 the radiometer (PRT-5), and Ch 3 to Ch 8 for the weather information. The system records data from channel 1 and channel 2 alternately for 48 times, before a fast sweep across the six weather channels, to form a single scan in the scan counter. The operation is illustrated in a block diagram, and the theory of operation is described. The outputs are written on a 7-track magnetic tape with IBM compatible form. The format of the tape and the playback computer programs are included. The micro-pac digital modules and a CIPHER model 70 tape recorder (Cipher Data Products) are used. One of the major characteristics of this system is that it is externally clocked by the spectroradiometer instead of taking data at intervals of various wavelengths by using internal-clocking.

  9. Raman and infrared spectroscopic study of boussingaultite and nickelboussingaultite

    NASA Astrophysics Data System (ADS)

    Culka, Adam; Jehlička, Jan; Němec, Ivan

    2009-08-01

    The Raman and infrared spectra of two secondary sulphate minerals, boussingaultite [(NH 4) 2Mg(SO 4) 2·6H 2O] and nickelboussingaultite [(NH 4) 2Ni,Mg(SO 4) 2·6H 2O] have been collected. Two bands observed at 983 and 990 cm -1 were attributed to the ν1(SO 42-) symmetric stretching vibration. The bands at 1133, 1096 and 1063 cm -1 in boussingaultite spectra and bands at 1149, 1093 and 1063 cm -1 in nickelboussingaultite spectra were attributed to the ν3(SO 42-) antisymmetric stretching vibration. The splitting of the ν4(SO 42-) bending vibration produced bands at 625 and 615 cm -1 in the boussingaultite spectra and 652, 624 and 602 cm -1 in the nickelboussingaultite spectra. Similarly, in the case of the ν2(SO 4) bending vibration, the bands were observed at 454 cm -1 in the boussingaultite spectra and 482, 457 and 440 cm -1 in the nickelboussingaultite spectra. The splitting of bands is the result of lowered symmetry of sulphate ions and possibly a result of substitution of Mg ions by Ni ions in nickelboussingaultite. The bands in the NH 4+ bending vibration region were observed at 1705 and 1678 cm -1 ( ν2), 1460 and 1438 cm -1 ( ν4) for the mineral boussingaultite. In the high wavenumber region the bands arising from the OH (bands above 3000 cm -1) and the NH 4+ (2940, 2918 and 2845 cm -1) stretching vibrations were identified.

  10. A Thermal Infrared Radiation Parameterization for Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Suarez, Max J.; Liang, Xin-Zhong; Yan, Michael M.-H.; Cote, Charles (Technical Monitor)

    2001-01-01

    This technical memorandum documents the longwave radiation parameterization developed at the Climate and Radiation Branch, NASA Goddard Space Flight Center, for a wide variety of weather and climate applications. Based on the 1996-version of the Air Force Geophysical Laboratory HITRAN data, the parameterization includes the absorption due to major gaseous absorption (water vapor, CO2, O3) and most of the minor trace gases (N2O, CH4, CFCs), as well as clouds and aerosols. The thermal infrared spectrum is divided into nine bands. To achieve a high degree of accuracy and speed, various approaches of computing the transmission function are applied to different spectral bands and gases. The gaseous transmission function is computed either using the k-distribution method or the table look-up method. To include the effect of scattering due to clouds and aerosols, the optical thickness is scaled by the single-scattering albedo and asymmetry factor. The parameterization can accurately compute fluxes to within 1% of the high spectral-resolution line-by-line calculations. The cooling rate can be accurately computed in the region extending from the surface to the 0.01-hPa level.

  11. NEAR-INFRARED SPECTROSCOPIC STUDY OF V1647 ORI

    SciTech Connect

    Brittain, Sean D.; Liskowsky, Joseph; Rettig, Terrence W.; Simon, Theodore; Gibb, Erika L.

    2010-01-01

    We present new high-resolution infrared echelle spectra of V1647 Ori, the young star that illuminates McNeil's nebula. From the start, V1647 Ori has been an enigmatic source that has defied classification, in some ways resembling eruptive stars of the FUor class and in other respects the EXor variables. V1647 Ori underwent an outburst in 2003 before fading back to its pre-outburst brightness in 2006. In 2008, it underwent a new outburst. In this paper, we present high-resolution K-band and M-band spectra from the W. M. Keck Observatory that were acquired during the 2008 outburst. We compare the spectra to spectra acquired during the previous outburst and quiescent phases. We find that the luminosity and full width at half maximum power of Br gamma increased as the star has brightened and decreased when the star faded, indicating that these phases are driven by variations in the accretion rate. We also show that the temperature of the CO emission has varied with the stellar accretion rate, confirming suggestions from modeling of the heating mechanisms of the inner disk. Finally, we find that the lowest energy blueshifted CO absorption lines originally reported in 2007 are no longer detected. The absence of these lines confirms the short-lived nature of the outflow launched at the start of the quiescent phase in 2006.

  12. Fourier transform infrared studies in hypergolic ignition of ionic liquids.

    PubMed

    Chambreau, Steven D; Schneider, Stefan; Rosander, Michael; Hawkins, Tom; Gallegos, Christopher J; Pastewait, Matthew F; Vaghjiani, Ghanshyam L

    2008-08-28

    A class of room-temperature ionic liquids (RTILs) that exhibit hypergolic activity toward fuming nitric acid is reported. Fast ignition of dicyanamide ionic liquids when mixed with nitric acid is contrasted with the reactivity of the ionic liquid azides, which show high reactivity with nitric acid, but do not ignite. The reactivity of other potential salt fuels is assessed here. Rapid-scan, Fourier transform infrared (FTIR) spectroscopy of the preignition phase indicates the evolution of N 2O from both the dicyanamide and azide RTILs. Evidence for the evolution of CO 2 and isocyanic acid (HNCO) with similar temporal behavior to N 2O from reaction of the dicyanamide ionic liquids with nitric acid is presented. Evolution of HN 3 is detected from the azides. No evolution of HCN from the dicyanamide reactions was detected. From the FTIR observations, biuret reaction tests, and initial ab initio calculations, a mechanism is proposed for the formation of N 2O, CO 2, and HNCO from the dicyanamide reactions during preignition. PMID:18681416

  13. Ribosomal DNA nanoprobes studied by Fourier transform infrared spectroscopy.

    PubMed

    Fagundes, Jaciara; Castilho, Maiara L; Téllez Soto, Claudio A; Vieira, Laís de Souza; Canevari, Renata A; Fávero, Priscila P; Martin, Airton A; Raniero, Leandro

    2014-01-24

    Paracoccidioides brasiliensis (P. brasiliensis) is a thermo-dimorphic fungus that causes paracoccidioidomycosis. Brazil epidemiological data shows that endemic areas are the subtropical regions, especially where agricultural activities predominate such as the Southeast, South, and Midwest. There are several tests to diagnose paracoccidioidomycosis, but they have many limitations such as low sensitivity, high cost, and a cross-reacting problem. In this work, gold nanoprobes were used to identify P. brasiliensis as an alternative diagnostic technique, which is easier to apply, costs less, and has great potential for application. The specific Ribosomal sequence of P. brasiliensis DNA was amplified and used to design the nanoprobes using a thiol-modified oligonucleotide. The results of positive and negative tests were done by UV-visible and Fourier Transform Infrared (FT-IR) measurements. The deconvolution of FT-IR sample spectra showed differences in the vibrational modes from the hydrogen bridge NHN and NHO bands that form the double helix DNA for samples matching the DNA sequence of nanoprobes that could be used to classify the samples.

  14. Studying hot exozodiacal dust with near-infrared interferometry

    NASA Astrophysics Data System (ADS)

    Absil, Olivier; Defrère, Denis; Le Bouquin, Jean-Baptiste; Mollier, Benjamin; Augereau, Jean-Charles; Coudé du Foresto, Vincent; Di Folco, Emmanuel; Ertel, Steve; ten Brummelaar, Theo

    2012-07-01

    Since our first detection of a resolved near-infrared emission around the main sequence star Vega, which we identified as the signature of hot dust grains close to the sublimation limit, we have been systematically searching for similar signatures around a magnitude-limited sample of nearby main sequence stars with the FLUOR instrument at the CHARA array. About 40 targets with spectral types ranging from A to K have been observed within the last 6 years, leading to first statistical trends on the occurence of the bright exozodi phenomenon as a function of spectral type. Our target sample is balanced between stars known to harbour cold dust populations from space-based missions (e.g., Spitzer, Herschel) and stars without cold dust, so that the occurence of abundant hot dust can also be correlated with the presence of large reservoirs of cold planetesimals. In this paper, we present preliminary conclusions from the CHARA/FLUOR survey. We also discuss the first results obtained in 2011/2012 with the new PIONIER visiting instrument at the VLTI, which is now used to extend our survey sample to the Southern hemisphere and to fainter targets. A first measurement of the exozodi/star flux ratio as a function of wavelength within the H band is presented, thanks to the low spectral resolution capability of PIONIER. Finally, we also briefly discuss our plans for extending the survey to fainter targets in the Northern hemisphere with an upgraded version of the FLUOR beam combiner.

  15. Laser surface texturing of cast iron steel: dramatic edge burr reduction and high speed process optimisation for industrial production using DPSS picosecond lasers

    NASA Astrophysics Data System (ADS)

    Bruneel, David; Kearsley, Andrew; Karnakis, Dimitris

    2015-07-01

    In this work we present picosecond DPSS laser surface texturing optimisation of automotive grade cast iron steel. This application attracts great interest, particularly in the automotive industry, to reduce friction between moving piston parts in car engines, in order to decrease fuel consumption. This is accomplished by partially covering with swallow microgrooves the inner surface of a piston liner and is currently a production process adopting much longer pulse (microsecond) DPSS lasers. Lubricated interface conditions of moving parts require from the laser process to produce a very strictly controlled surface topography around the laser formed grooves, whose edge burr height must be lower than 100 nm. To achieve such a strict tolerance, laser machining of cast iron steel was investigated using an infrared DPSS picosecond laser (10ps duration) with an output power of 16W and a repetition rate of 200 kHz. The ultrashort laser is believed to provide a much better thermal management of the etching process. All studies presented here were performed on flat samples in ambient air but the process is transferrable to cylindrical geometry engine liners. We will show that reducing significantly the edge burr below an acceptable limit for lubricated engine production is possible using such lasers and remarkably the process window lies at very high irradiated fluences much higher that the single pulse ablation threshold. This detailed experimental work highlights the close relationship between the optimised laser irradiation conditions as well as the process strategy with the final size of the undesirable edge burrs. The optimised process conditions are compatible with an industrial production process and show the potential for removing extra post)processing steps (honing, etc) of cylinder liners on the manufacturing line saving time and cost.

  16. Detection of nonlinear picosecond acoustic pulses by time-resolved Brillouin scattering

    SciTech Connect

    Gusev, Vitalyi E.

    2014-08-14

    In time-resolved Brillouin scattering (also called picosecond ultrasonic interferometry), the time evolution of the spatial Fourier component of an optically excited acoustic strain distribution is monitored. The wave number is determined by the momentum conservation in photon-phonon interaction. For linear acoustic waves propagating in a homogeneous medium, the detected time-domain signal of the optical probe transient reflectivity shows a sinusoidal oscillation at a constant frequency known as the Brillouin frequency. This oscillation is a result of heterodyning the constant reflection from the sample surface with the Brillouin-scattered field. Here, we present an analytical theory for the nonlinear reshaping of a propagating, finite amplitude picosecond acoustic pulse, which results in a time-dependence of the observed frequency. In particular, we examine the conditions under which this information can be used to study the time-evolution of the weak-shock front speed. Depending on the initial strain pulse parameters and the time interval of its nonlinear transformation, our theory predicts the detected frequency to either be monotonically decreasing or oscillating in time. We support these theoretical predictions by comparison with available experimental data. In general, we find that picosecond ultrasonic interferometry of nonlinear acoustic pulses provides access to the nonlinear acoustic properties of a medium spanning most of the GHz frequency range.

  17. Generation of picosecond pulses in a dye laser excited by radiation from an argon laser with passively locked modes

    SciTech Connect

    Vinogradova, A.A.; Krindach, D.P.; Nazarov, B.I.; Tsapenko, A.M.

    1980-01-01

    Passive locking of argon laser modes was used in generation of tunable picosecond pulses in a synchronously excited dye laser. An experimental study was made of the characteristics of the dye laser radiation as a function of the argon laser characteristics.

  18. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  19. Study of jamming of the frequency modulation infrared seekers

    NASA Astrophysics Data System (ADS)

    Qian, Fang; Guo, Jin; Shao, Jun-feng; Wang, Ting-feng

    2013-09-01

    The threat of the IR guidance missile is a direct consequence of extensive proliferation of the airborne IR countermeasure. The aim of a countermeasure system is to inject false information into a sensor system to create confusion. Many optical seekers have a single detector that is used to sense the position of its victim in its field of view. A seeker has a spinning reticle in the focal plane of the optical system that collects energy from the thermal scene and focuses it on to the detector. In this paper, the principle of the conical-scan FM reticle is analyzed. Then the effect that different amplitude or frequency modulated mid-infrared laser pulse acts on the reticle system is simulated. When the ratio of jamming energy to target radiation (repression) gradually increases, the azimuth error and the misalignment angle error become larger. The results show that simply increasing the intensity of the jamming light achieves little, but it increases the received signal strength of the FM reticle system ,so that the target will be more easily exposed. A slow variation of amplitude will warp the azimuth information received by the seeker, but the target can't be completely out of the missile tracking. If the repression and the jamming frequency change at the same time, the jamming effects can be more obvious. When the jamming signal's angular frequency is twice as large as the carrier frequency of the reticle system, the seeker will can't receive an accurate signal and the jamming can be achieved. The jamming mechanism of the conical-scan FM IR seeker is described and it is helpful to the airborne IR countermeasure system.

  20. 500 picosecond TDC for DIRC at BABAR

    SciTech Connect

    Lebbolo, H.; Bailly, P.; Chauveau, J.

    1997-12-31

    A 16 channel TDC chip has been developed at LPNHE Paris, to equip the Front-End electronics of the Detector of Internally Reflected Cerenkov light (DIRC) of the BABAR experiment at the SLAC B factory (Stanford, USA). Binning is 500 picosecond, conversion time is 32 ns, with a fall range of 32 {mu}s. The chip integrates channel buffering and selective readout of data falling within a programmable window defined by the level one trigger latency and resolution. The selective readout allows to manage random inputs at a maximum average rate of 100 kHz on each channel and makes data available at any time a trigger occurs. The maximum average rate of L1 accept trigger will be 2 kHz. The chip, housed in a 68 pin PLCC package, is designed in 0.7 {mu}m CMOS technology and manufactured by ATMEL ES2. The TDC section and channel FIFOs are full custom designs. The TDC uses 16 independent voltage controlled digital delay lines and a 17th calibration channel which allows to tune the delays on the 59.5 MHZ reference clock. The selective readout algorithm has been synthesized from Verilog description and uses ATMEL ES2 standard cells. Die size is 36 mm2 and power less than 100 mW with all inputs fired at 100 kHZ. Prototypes test results show performances better than the specifications for the chip to be used on the DIRC detector. The ten production prototypes have been delivered mid May 1997.

  1. Infrared and infrared emission spectroscopic study of selected magnesium carbonate minerals containing ferric iron--implications for the geosequestration of greenhouse gases.

    PubMed

    Frost, Ray L; Bahfenne, Silmarilly; Graham, Jessica

    2008-12-15

    The proposal to remove greenhouse gases by pumping liquid carbon dioxide several kilometres below ground level implies that many carbonate containing minerals will be formed. Among these minerals, the formation of two hydrotalcite-like minerals coalingite and brugnatellite is possible, thus necessitating a study of such minerals and their thermal stability. The two such carbonate-bearing minerals brugnatellite and coalingite have been characterised by a combination of infrared and infrared emission spectroscopy. Infrared emission spectroscopy is most useful to determine the stability of these minerals. The infrared spectra of the OH stretching region are characterised by OH and water stretching vibrations. Intense (CO3)(2-) symmetric and antisymmetric stretching vibrations support the concept that the carbonate ion is distorted in these minerals. The position of the water bending vibration indicates that the water is strongly hydrogen bonded in the mineral structure. IES spectra show the temperature range of the thermal stability of these minerals.

  2. A primary study on finding hot groundwater using infrared remote sensing

    NASA Astrophysics Data System (ADS)

    Qiao, Y.; Wu, Q.

    Hot groundwater is a kind of valuable natural resources to be explored utilized. Shanxi Province, located in the eastern Loess Plateau of China, is rich in geothermal resources, most of which was found in irrigation well drilling or geological survey. Basic study is weak. Now new developed Remote Sensing technique provides geothermal study with an advanced way. Air-RS information of thermal infrared and dada from thermal channel of Meteorological Landset AVHRR has been used widely. A thermal infrared channel (TM6) was installed in the U. S. second Landset, Its resolving power of space is as high as 120 m, 10 times more t an one ofh AVHRR. A Landset earth recourses launched by China and Brazil (CBERS-1) in 1999, including a spectrum of thermal infrared. It is paid a great interested and attention to survey geothermal resources using thermal infrared. This article is a brief introduction of finding hot groundwater with on the bases of differences of thermal radiation of objects reflected by thermal infrared in the Landset, and treated with HIS colors changes. This study provides an advanced way widely used to exploit hot groundwater and to promote the development of tourism and geothermal medical in China.

  3. Interpreting picosecond acoustics in the case of low interface stiffness.

    PubMed

    Hohensee, Gregory T; Hsieh, Wen-Pin; Losego, Mark D; Cahill, David G

    2012-11-01

    Analysis of data acquired in time-domain thermoreflectance (TDTR) experiments requires accurate measurements of the thickness of the metal film optical transducer that absorbs energy from the pump optical pulse and provides a temperature dependent reflectivity that is interrogated by the probe optical pulse. This thickness measurement is typically accomplished using picosecond acoustics. The presence of contaminants and native oxides at the interface between the sample and transducer often produce a picosecond acoustics signal that is difficult to interpret. We describe heuristics for addressing this common difficulty in interpreting picosecond acoustic data. The use of these heuristics can reduce the propagation of uncertainties and improve the accuracy of TDTR measurements of thermal transport properties.

  4. The Laser-assisted photoelectric effect of He, Ne, Ar and Xe in intense extreme ultraviolet and infrared laser fields

    NASA Astrophysics Data System (ADS)

    Hayden, P.; Dardis, J.; Hough, P.; Richardson, V.; Kennedy, E. T.; Costello, J. T.; Düsterer, S.; Redlin, H.; Feldhaus, J.; Li, W. B.; Cubaynes, D.; Meyer, M.

    2016-02-01

    In this paper, we report results on two-colour above-threshold ionisation, where extreme ultraviolet pulses of femtosecond duration were synchronised to intense infrared laser pulses of picosecond duration, in order to study the laser-assisted photoelectric effect of atomic helium, neon, krypton and xenon which leads to the appearance of characteristic sidebands in the photoelectron spectra. The observed trends are found to be well described by a simple model based on the soft-photon approximation, at least for the relatively low optical intensities of up to ? employed in these early experiments.

  5. High power industrial picosecond laser from IR to UV

    NASA Astrophysics Data System (ADS)

    Saby, Julien; Sangla, Damien; Pierrot, Simonette; Deslandes, Pierre; Salin, François

    2013-02-01

    Many industrial applications such as glass cutting, ceramic micro-machining or photovoltaic processes require high average and high peak power Picosecond pulses. The main limitation for the expansion of the picosecond market is the cost of high power picosecond laser sources, which is due to the complexity of the architecture used for picosecond pulse amplification, and the difficulty to keep an excellent beam quality at high average power. Amplification with fibers is a good technology to achieve high power in picosecond regime but, because of its tight confinement over long distances, light undergoes dramatic non linearities while propagating in fibers. One way to avoid strong non linearities is to increase fiber's mode area. Nineteen missing holes fibers offering core diameter larger than 80μm have been used over the past few years [1-3] but it has been shown that mode instabilities occur at approximately 100W average output power in these fibers [4]. Recently a new fiber design has been introduced, in which HOMs are delocalized from the core to the clad, preventing from HOMs amplification [5]. In these so-called Large Pitch Fibers, threshold for mode instabilities is increased to 294W offering robust single-mode operation below this power level [6]. We have demonstrated a high power-high efficiency industrial picosecond source using single-mode Large Pitch rod-type fibers doped with Ytterbium. Large Pitch Rod type fibers can offer a unique combination of single-mode output with a very large mode area from 40 μm up to 100μm and very high gain. This enables to directly amplify a low power-low energy Mode Locked Fiber laser with a simple amplification architecture, achieving very high power together with singlemode output independent of power level or repetition rate.

  6. A semiconductor injection-switched high-pressure sub-10-picosecond carbon dioxide laser amplifier

    NASA Astrophysics Data System (ADS)

    Hughes, Michael Kon Yew

    A multiatmospheric-pressure-broadened CO2 laser amplifier was constructed to amplify sub-10-picosecond pulses generated with semiconductor switching. High-intensity, mid-infrared, amplified pulses have many applications: especially in fields such as non-linear optics, laser-plasma interaction, and laser particle acceleration. The injected pulses are produced by exciting GaAs (or an engineered, fast-recombination time semiconductor) with an ultrafast visible laser pulse to induce transient free carriers with sufficient density to reflect a co-incident hybrid-CO2 laser pulse. The short pulse is injected directly into the regenerative amplifier cavity from an intra-cavity semiconductor switch. The CO2-gas-mix amplifier is operated at 1.24 MPa which is sufficient to collisionally broaden the individual rotational spectral lines so that they merge to produce a gain spectrum wide enough to support pulses less than 10 ps long. After sufficient amplification, the pulse is switched out with another semiconductor switch pumped with a synchronized visible-laser pulse. This system is demonstrated and analysed spectrally and temporally. The pulse-train spectral analysis is done for a GaAs-GaAs double-switch arrangement using a standard spectrometer and two HgCdTe detectors; one of which is used for a reference signal. An infrared autocorrelator was designed and constructed to temporally analyse the pulse trains emerging from the amplifier. Interpretation of the results was aided by the development of a computer model for short-pulse amplification which incorporated saturation effects, rotational- and vibrational-mode energy redistribution between pulse round trips, and the gain enhancement due to one sequence band. The results show that a sub-10-picosecond pulse is injected into the cavity and that it is amplified with some trailing pulses at 18 ps intervals generated by coherent effects. The energy level reached, estimated through modelling, was >100 mJ/cm2.

  7. Picosecond Pulse Radiolysis of Highly Concentrated Carbonate Solutions.

    PubMed

    Ghalei, Mohammad; Ma, Jun; Schmidhammer, Uli; Vandenborre, Johan; Fattahi, Massoud; Mostafavi, Mehran

    2016-03-10

    Highly concentrated potassium carbonate aqueous solutions are studied by picosecond pulse radiolysis with the purpose of exploring the formation processes of carbonate radical CO3(•-). The transient absorption band of solvated electron produced by ionizing is markedly shifted from 715 to 600 nm when the solute concentration of K2CO3 is 5 mol L(-1). This spectral shift is even more important than that observed for the solvated electron in 10 mol L(-1) KOH solutions. The broad absorption band of solvated electron in K2CO3 solutions overlaps with that of carbonate radical CO3(•-) formed at ultrashort time. Nitrate ion is used to scavenge the solvated electron and to observe the contribution of carbonate radical CO3(•-). The analysis of the amplitude and the kinetics of carbonate radical formation in highly concentrated solutions shows that CO3(•-) is formed within the electron pulse (7 ps) by two parallel mechanisms: a direct effect on the solute and the oxidation of the solute by water radical hole H2O(•+). These two mechanisms are followed by an additional one, by reaction between the solute and OH(•) radical especially in lower concentration. The radiolytic yield of each process is discussed. PMID:26885876

  8. Improved infrared cell reactor for use in transient response studies: the catalytic oxidation of CO reexamined

    SciTech Connect

    Nagai, M.; Lucietto, L.L.; Li, Y.; Gonzalez, R.D.

    1986-10-01

    Recent advances in rapid scan infrared spectroscopy have revived an interest in in situ transient response studies in catalysis. However, the requirement of combining a small dead space cell volume reactor essential for transient response studies with single-pass differential flow capabilities has not yet been met. In order to meet these requirements, an infrared cell-reactor should conform to the following: (1) the residence time in the infrared cell-reactor should be less than the time required for scanning the spectrum; (2) the reactant gases should preferably be forced through the sample disk with little or no leakage around the edges: (3) the outlet from the infrared cell-reactor should be properly interfaced with a gas chromatograph or another suitable analytical measuring device such as a quadrupole mass spectrometer; and (4) the cell should be constructed to handle adequate heating schedules. In this paper the authors report on a new design which combines the features. The authors also consider the catalytic oxidation of CO over Pt/SiO/sub 2/ to illustrate the transient capabilities of the infrared cell-reactor. 11 references.

  9. Molecular evolution of the infrared sensory gene TRPA1 in snakes and implications for functional studies.

    PubMed

    Geng, Jie; Liang, Dan; Jiang, Ke; Zhang, Peng

    2011-01-01

    TRPA1 is a calcium ion channel protein recently identified as the infrared receptor in pit organ-containing snakes. Therefore, understanding the molecular evolution of TRPA1 may help to illuminate the origin of "heat vision" in snakes and reveal the molecular mechanism of infrared sensitivity for TRPA1. To this end, we sequenced the infrared sensory gene TRPA1 in 24 snake species, representing nine snake families and multiple non-snake outgroups. We found that TRPA1 is under strong positive selection in the pit-bearing snakes studied, but not in other non-pit snakes and non-snake vertebrates. As a comparison, TRPV1, a gene closely related to TRPA1, was found to be under strong purifying selection in all the species studied, with no difference in the strength of selection between pit-bearing snakes and non-pit snakes. This finding demonstrates that the adaptive evolution of TRPA1 specifically occurred within the pit-bearing snakes and may be related to the functional modification for detecting infrared radiation. In addition, by comparing the TRPA1 protein sequences, we identified 11 amino acid sites that were diverged in pit-bearing snakes but conserved in non-pit snakes and other vertebrates, 21 sites that were diverged only within pit-vipers but conserved in the remaining snakes. These specific amino acid substitutions may be potentially functional important for infrared sensing.

  10. Synchronization of sub-picosecond electron and laser pulses

    SciTech Connect

    Rosenzweig, J.B.; Le Sage, G.P.

    1999-07-01

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail. (AIP) {copyright} {ital 1999 American Institute of Physics.}

  11. Synchronization of sub-picosecond electron and laser pulses

    SciTech Connect

    Rosenzweig, J. B.; Le Sage, G. P.

    1999-07-12

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail.

  12. Use of in situ Fourier transform infrared spectroscopy to study freezing and drying of cells.

    PubMed

    Wolkers, Willem F; Oldenhof, Harriëtte

    2015-01-01

    An infrared spectrum gives information about characteristic molecular vibrations of specific groups in molecules. Fourier transform infrared spectroscopy can be applied to study lipids and proteins in cells or tissues. Spectra can be collected during cooling, heating, or dehydration of a sample using a temperature-controlled sample holder or a sample holder for controlled dehydration. In the current chapter, acquisition and analysis of infrared spectra during cooling, warming, or dehydration is described. Spectra analysis involving assessment of specific band positions, areas, or ratios is described. Special emphasis is given on studying membrane phase behavior and protein denaturation in cells or tissues. In addition, methods are presented to determine the water-to-ice phase change during freezing, dehydration kinetics, and the glass transition temperature of amorphous systems.

  13. Picosecond intersubband hole relaxation in p-type quantum wells

    SciTech Connect

    Xu, Z.; Fauchet, P.M.; Rella, C.W.; Schwettman, H.A.

    1995-12-31

    We report the first direct measurement of the relaxation time of holes in p-type quantum wells using tunable, subpicosecond mid-infrared laser pulses in a pump-probe arrangement. The QW layers consisted of 50 In{sub 0.5}Ga{sub 0.5}As/Al{sub 0.5}Ga{sub 0.5}As periods. The In{sub 0.5}Ga{sub 0.5}As well was 4 nm wide and the Al{sub 0.5}Ga{sub 0.5}As barrier was 8 nm wide. The dopant concentration was 10{sup 19} CM{sup -3} which corresponds to a sheet density of 1.2 x 10{sup 13} CM{sup -2}. The room temperature IR spectrum showed a 50 meV wide absorption peak at 5.25 {mu}m (220 meV). This energy agrees with the calculated n=1 heavy hole to n=1 light hole transition energy of 240 meV (150 meV for strain and 90 meV for confinement). The large absorption width results from hole-hole scattering and the difference in dispersion relations between the two subbands. The equal-wavelength pump-probe transmission measurements were performed using the Stanford free electron laser (FEL). The FEL pulses were tuned between 4 and 6 {mu} m and their duration was less than 1 ps. The measurements were performed as a function of temperature, pump wavelength and intensity (from 0.3 to 10 GW/cm{sup 2}). In all our experiments, we find an increase of transmission (decrease of absorption or bleaching) following photopumping, which recovers as a single exponential with a time constant (relaxation time) of the order of 1 picosecond. The maximum change in transmission is linear with pump 2 intensity below 1 GW/cm{sup 2} and saturates to {approximately}3% with a saturation intensity I{sub sat} of 3 GW/cm{sup 2}. As the saturation regime is entered, the relaxation time increases from 0.8 ps to 1.8 ps. This relaxation time depends on the temperature T: it increases from 0.8 ps to 1.3 ps as T decreases from 300 K to 77 K. Finally, when we tune the laser through the absorption band, the magnitude of the signal changes but its temporal behavior does not change, within the accuracy of the measurements.

  14. Optically active substituted polyacetylene@carbon nanotube hybrids: Preparation, characterization and infrared emissivity property study

    SciTech Connect

    Bu, Xiaohai; Zhou, Yuming Zhang, Tao; Wang, Yongjuan; Zhang, Zewu; He, Man

    2014-08-15

    Optically active substituted polyacetylene@multiwalled carbon nanotubes (SPA@MWCNTs) nanohybrids were fabricated by wrapping helical SPA copolymers onto the surface of modified nanotubes through ester bonding linkage. SPA copolymer based on chiral phenylalanine and serine was pre-polymerized by a rhodium zwitterion catalyst in THF, and evidently proved to possess strong optical activity and adopt a predominately one-handed helical conformation. Various characterizations including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) demonstrated that the SPA had been covalently grafted onto the nanotubes without destroying their original graphite structure. The wrapped SPA was found to exhibit an enhancement in thermal stability and still maintained considerable optical activity after grafting. The infrared emissivity property of the nanohybrids at 8–14 μm was investigated in addition. The results indicated that the SPA@MWCNTs hybrid matrix could possess a much lower infrared emissivity value (ε=0.707) than raw MWCNTs, which might be due to synergistic effect of the unique helical conformation of optically active SPA and strengthened interfacial interaction between the organic polymers and inorganic nanoparticles. - Graphical abstract: Optically active SPA@MWCNTs nanohybrids with low infrared emissivity. - Highlights: • Synthesis of optically active SPA copolymer derived from serine and phenylalanine. • Preparation and characterization of optically active SPA@MWCNTs nanohybrids. • Application study of the SPA@MWCNTs nanohybrids (ε=0.707) in lowering the infrared emissivity.

  15. Study on the diagnostic system of scoliosis by using infrared camera.

    PubMed

    Jeong, Jin-hyoung; Park, Eun-jeong; Cho, Chang-ok; Kim, Yoon-jeong; Lee, Sang-sik

    2015-01-01

    In this study, the radiation generated in the diagnosis of scoliosis, to solve the problems by using an infrared camera and an optical marker system that can diagnose scoliosis developed. System developed by the infrared camera attached to the optical spinal curvature is recognized as a marker to shoot the angle between the two optical markers are measured. Measurement of angle, we used the Cobb's Angle method used in the diagnosis of spinal scoliosis. We developed a software to be able to output to the screen using an infrared camera to diagnose spinal scoliosis. Software is composed of camera output unit was manufactured in Labview, angle measurement unit, in Cobb's Angle measurement unit. In the future, kyphosis, Hallux Valgus, such as the diagnosis of orthopedic disorders that require the use of a diagnostic system is expected case.

  16. POLARIZED RADIO SOURCES: A STUDY OF LUMINOSITY, REDSHIFT, AND INFRARED COLORS

    SciTech Connect

    Banfield, Julie K.; George, Samuel J.; Taylor, A. Russ; Stil, Jeroen M.; Kothes, Roland; Scott, Douglas

    2011-05-20

    The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic Survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used Very Large Array observations with a total intensity rms of 87 {mu}Jy beam{sup -1} to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04 < z < 3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.

  17. Comparative Study Using Different Infrared Zones of the Solventless Activation of Organic Reactions

    PubMed Central

    Córdova, María Olivia Noguez; Flores Ramírez, Carlos I.; Bejarano, Benjamín Velasco; Arroyo Razo, Gabriel A.; Pérez Flores, Francisco J.; Tellez, Vladimir Carranza; Ruvalcaba, René Miranda

    2011-01-01

    In this work, the results of a study comparing the use of irradiation from different regions of the infrared spectrum for the promotion of several organic reactions, are presented and discussed. This use of eco-conditions provides a green approach to chemical synthesis. A set of ten different organic reactions were evaluated, including the Knoevenagel, Hantzsch, Biginelli and Meldrum reactions. It is important to highlight the use of a commercial device that produces infrared irradiation in the near infrared region and its distribution by convection providing heating uniformity, significantly reducing reaction times, achieving good yields and proceeding in the absence of solvent. It is also worth noting that a variety of different reactions may be performed at the same time. Finally, the products obtained were identified using TLC, together with corresponding MS-data, complementarily in comparison of NMR 1H and 13C data with literature information. PMID:22272092

  18. [Study of infrared spectroscopy quantitative analysis method for methane gas based on data mining].

    PubMed

    Zhang, Ai-Ju

    2013-10-01

    Monitoring of methane gas is one of the important factors affecting the coal mine safety. The online real-time monitoring of the methane gas is used for the mine safety protection. To improve the accuracy of model analysis, in the present paper, the author uses the technology of infrared spectroscopy to study the gas infrared quantitative analysis algorithm. By data mining technology application in multi-component infrared spectroscopy quantitative analysis algorithm, it was found that cluster analysis partial least squares algorithm is obviously superior to simply using partial least squares algorithm in terms of accuracy. In addition, to reduce the influence of the error on the accuracy of model individual calibration samples, the clustering analysis was used for the data preprocessing, and such denoising method was found to improve the analysis accuracy.

  19. Tree Canopy Characterization for EO-1 Reflective and Thermal Infrared Validation Studies: Rochester, New York

    NASA Technical Reports Server (NTRS)

    Ballard, Jerrell R., Jr.; Smith, James A.

    2002-01-01

    The tree canopy characterization presented herein provided ground and tree canopy data for different types of tree canopies in support of EO-1 reflective and thermal infrared validation studies. These characterization efforts during August and September of 2001 included stem and trunk location surveys, tree structure geometry measurements, meteorology, and leaf area index (LAI) measurements. Measurements were also collected on thermal and reflective spectral properties of leaves, tree bark, leaf litter, soil, and grass. The data presented in this report were used to generate synthetic reflective and thermal infrared scenes and images that were used for the EO-1 Validation Program. The data also were used to evaluate whether the EO-1 ALI reflective channels can be combined with the Landsat-7 ETM+ thermal infrared channel to estimate canopy temperature, and also test the effects of separating the thermal and reflective measurements in time resulting from satellite formation flying.

  20. Study on the diagnostic system of scoliosis by using infrared camera.

    PubMed

    Jeong, Jin-hyoung; Park, Eun-jeong; Cho, Chang-ok; Kim, Yoon-jeong; Lee, Sang-sik

    2015-01-01

    In this study, the radiation generated in the diagnosis of scoliosis, to solve the problems by using an infrared camera and an optical marker system that can diagnose scoliosis developed. System developed by the infrared camera attached to the optical spinal curvature is recognized as a marker to shoot the angle between the two optical markers are measured. Measurement of angle, we used the Cobb's Angle method used in the diagnosis of spinal scoliosis. We developed a software to be able to output to the screen using an infrared camera to diagnose spinal scoliosis. Software is composed of camera output unit was manufactured in Labview, angle measurement unit, in Cobb's Angle measurement unit. In the future, kyphosis, Hallux Valgus, such as the diagnosis of orthopedic disorders that require the use of a diagnostic system is expected case. PMID:26405878

  1. Analytical estimation of solid angle subtended by complex well-resolved surfaces for infrared detection studies.

    PubMed

    Mahulikar, Shripad P; Potnuru, Santosh K; Kolhe, Pankaj S

    2007-08-01

    The solid angle (Omega) subtended by the hot power-plant surfaces of a typical fighter aircraft, on the detector of an infrared (IR) guided missile, is analytically obtained. The use of the parallel rays projection method simplifies the incorporation of the effect of the optical blocking by engine surfaces, on Omega-subtended. This methodology enables the evaluation of the relative contribution of the IR signature from well-resolved distributed sources, and is important for imaging infrared detection studies. The complex 3D surface of a rear fuselage is projected onto an equivalent planar area normal to the viewing aspect, which would give the same Omega-subtended. PMID:17676106

  2. A feasibility study: California Department of Forestry and Fire Protection utilization of infrared technologies for wildland fire suppression and management

    NASA Technical Reports Server (NTRS)

    Nichols, J. D.; Britten, R. A.; Parks, G. S.; Voss, J. M.

    1990-01-01

    NASA's JPL has completed a feasibility study using infrared technologies for wildland fire suppression and management. The study surveyed user needs, examined available technologies, matched the user needs with technologies, and defined an integrated infrared wildland fire mapping concept system configuration. System component trade-offs were presented for evaluation in the concept system configuration. The economic benefits of using infrared technologies in fire suppression and management were examined. Follow-on concept system configuration development and implementation were proposed.

  3. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  4. Do Infants Recognize the Arcimboldo Images as Faces? Behavioral and Near-Infrared Spectroscopic Study

    ERIC Educational Resources Information Center

    Kobayashi, Megumi; Otsuka, Yumiko; Nakato, Emi; Kanazawa, So; Yamaguchi, Masami K.; Kakigi, Ryusuke

    2012-01-01

    Arcimboldo images induce the perception of faces when shown upright despite the fact that only nonfacial objects such as vegetables and fruits are painted. In the current study, we examined whether infants recognize a face in the Arcimboldo images by using the preferential looking technique and near-infrared spectroscopy (NIRS). In the first…

  5. 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.

  6. Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution.

    PubMed

    Henn, T; Kiessling, T; Ossau, W; Molenkamp, L W; Biermann, K; Santos, P V

    2013-12-01

    We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast "white light" supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

  7. Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution

    SciTech Connect

    Henn, T.; Kiessling, T. Ossau, W.; Molenkamp, L. W.; Biermann, K.; Santos, P. V.

    2013-12-15

    We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast “white light” supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

  8. Alignment and Polarization Sensitivity Study for the Cassini-Composite InfraRed Spectrometer (CIRS) Far InfraRed (FIR) Interferometer

    NASA Technical Reports Server (NTRS)

    Crooke, Julie A.; Hagopian, John G.

    1998-01-01

    The Composite InfraRed Spectrometer (CIRS) instrument flying on the Cassini spacecraft to Saturn is a cryogenic spectrometer with far-infrared (FIR) and mid-infrared (MIR) channels. The CIRS FIR channel is a polarizing interferometer that contains three polarizing grid components. These components are an input polarizer, a polarizing beamsplitter, and an output polarizer/analyzer. They consist of a 1.5 micron thick mylar substrate with 2 gm wide copper wires, with 2 gm spacing (4 micron pitch) photolithographically deposited on the substrate. This paper details the polarization sensitivity studies performed on the output polarizer/analyzer, and the alignment sensitivity studies performed on the input polarizer and beamsplitter components in the FIR interferometer.

  9. Numerical study on the influence of aluminum on infrared radiation signature of exhaust plume

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Ye, Qing-qing; Li, Shi-peng; Wang, Ning-fei

    2013-09-01

    The infrared radiation signature of exhaust plume from solid propellant rockets has been widely mentioned for its important realistic meaning. The content of aluminum powder in the propellants is a key factor that affects the infrared radiation signature of the plume. The related studies are mostly on the conical nozzles. In this paper, the influence of aluminum on the flow field of plume, temperature distribution, and the infrared radiation characteristics were numerically studied with an object of 3D quadrate nozzle. Firstly, the gas phase flow field and gas-solid multi phase flow filed of the exhaust plume were calculated using CFD method. The result indicates that the Al203 particles have significant effect on the flow field of plume. Secondly, the radiation transfer equation was solved by using a discrete coordinate method. The spectral radiation intensity from 1000-2400 cm-1 was obtained. To study the infrared radiation characteristics of exhaust plume, an exceptional quadrate nozzle was employed and much attention was paid to the influences of Al203 particles in solid propellants. The results could dedicate the design of the divert control motor in such hypervelocity interceptors or missiles, or be of certain meaning to the improvement of ingredients of solid propellants.

  10. Advanced far infrared detector and double donor studies in Ge

    SciTech Connect

    Olsen, C.S.

    1994-12-01

    This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.

  11. Far infrared, near infrared, and radio molecular line studies of HFE 2, HFE 3, and FJM 6

    NASA Technical Reports Server (NTRS)

    Fischer, J.; Cassar, L.; Righini-Cohen, G.; Simon, M.

    1979-01-01

    Far-infrared, near-infrared, and radio molecular-line observations of the regions of HFE 2, HFE 3, and FJM 6 are described. At positions of high molecular column density nearest to the reported positions of these sources, their infrared emission cannot be confirmed at upper bounds below those of the original detection. Near-infrared observations of the FJM 6 region (which includes the Bok globule Barnard 361) reveal a number of stellar sources, most of which are behind the molecular cloud and are reddened by it. Visual extinction through B 361 estimated by star counts yields A sub V/N(/C-13/O) = 3.7 + or - 1.6) x 10 to the -16th mag sq cm. The gas temperature and the upper bound on the dust temperature in the FJM 6 region are consistent with cosmic-ray heating of the cloud, while the values of these parameters for the clouds in the HFE 2 and HFE 3 regions do not appear consistent with either cosmic-ray or radiative heating.

  12. Infrared laser heating for studies of cellulose degradation

    SciTech Connect

    Jackson, J.P.; Arthurs, E.; Schwalbe, L.A.; Sega, R.M.; Windish, D.; Long, W.H.; Stappaerts, E.A.

    1988-09-15

    We describe a new technique for studying thermally induced chemical transformations in cellulose. The apparatus consists of a carbon dioxide laser for heating, an IR thermometer, and an optical reflectance spectrometer for tracking the progressive discoloration of the sample. To illustrate the technique, we present measurements from a single piece of sample linen along five isotherms in the 200--290/sup 0/C range. We derive an algebraic expression for the reflectivity of the sample as a function of the areal concentrations of the chromophoric states produced at temperature. The results are then explained in terms of first-order chemical rate theory and a four-step model. From the measurements we derive the activation energies, Arrhenius constants, and reflectivities of the chromophoric states.

  13. Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies

    NASA Astrophysics Data System (ADS)

    Kwiatek, Anna; Mielke, Zofia

    2015-01-01

    A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(2p,2d) study of pyridoxal was performed. The calculations resulted in five stable PLHB conformers stabilized by intramolecular Osbnd H⋯O bonding between phenolic OH and carbonyl Cdbnd O groups and another thirteen conformers in which OH or/and aldehyde groups are rotated by 180° around CO or/and CC bonds leading, respectively, to formation of PLO, PLA and PLOA conformers. The analysis of the spectra of the as-deposited matrix indicated that two most stable PLHB1 and PLHB2 conformers with intramolecular hydrogen bond are present in the matrix. The exposure of the PL/Ar matrix to mercury lamp radiation (λ > 345 nm) induced conformational change of PLHB isomers to PLOA ones.

  14. Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies.

    PubMed

    Kwiatek, Anna; Mielke, Zofia

    2015-01-25

    A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(2p,2d) study of pyridoxal was performed. The calculations resulted in five stable PLHB conformers stabilized by intramolecular O-H⋯O bonding between phenolic OH and carbonyl C=O groups and another thirteen conformers in which OH or/and aldehyde groups are rotated by 180° around CO or/and CC bonds leading, respectively, to formation of PLO, PLA and PLOA conformers. The analysis of the spectra of the as-deposited matrix indicated that two most stable PLHB1 and PLHB2 conformers with intramolecular hydrogen bond are present in the matrix. The exposure of the PL/Ar matrix to mercury lamp radiation (λ>345 nm) induced conformational change of PLHB isomers to PLOA ones. PMID:25173527

  15. Shuttle infrared telescope facility (SIRTF) preliminary design study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    An overall picture of the SIRTF system is first presented, including the telescope, focal plane instruments, cryogen supply, shuttle and spacelab support subsystems, mechanical and data interfaces with the vehicles, ground support equipment, and system requirements. The optical, mechanical, and thermal characteristics of the telescope are then evaluated, followed by a description of the SIRTF internal stabilization subsystem and its interface with the IPS. Expected performance in the shuttle environment is considered. Tradeoff studies are described, including the Gregorian versus the Cassegrain telescope, aperture diameter tradeoff, a CCD versus an image dissector for the star tracker, the large ambient telescope versus the SIRTF, and a dedicated gimbal versus the IPS. Operations from integration through launch and recovery are also discussed and cost estimates for the program are presented.

  16. Processing infrared images for target detection: A literature study

    NASA Astrophysics Data System (ADS)

    Alblas, B. P.

    1988-07-01

    Methods of image processing applied to IR images to obtain better detection and/or recognition of military targets, particularly vehicles, are reviewed. The following subjects are dealt with: histogram specification, scanline degradation, correlation, clutter and noise. Only a few studies deal with the effects of image processing on human performance. Most of the literature concerns computer vision. Local adaptive and image dependent techniques appear to be the most promising methods of obtaining higher observation performance. In particular the size-contrast box filter and histogram specification methods seem to be suitable. There is a need for a generally applicable definition of image quality and clutter level to evaluate the utility of a specified algorithm. Proposals for further research are given.

  17. Time-resolved infrared studies of protein conformational dynamics

    SciTech Connect

    Woodruff, W.H.; Causgrove, T.P.; Dyer, R.B.; Callender, R.H.

    1994-12-01

    We have demonstrated that TRIR in the amide I region gives structural information regarding protein conformational changes in realtime, both on processes involved in the development of the functional structure (protein folding) and on protein structural changes that accompany the functional dynamics of the native structure. Assignment of many of the amide I peaks to specific amide or sidechain structures will require much additional effort. Specifically, the congestion and complexity of the protein vibrational spectra dictate that isotope studies are an absolute requirement for more than a qualitative notion of the structural interpretation of these measurements. It is clear, however, that enormous potential exists for elucidating structural relaxation dynamics and energetics with a high degree of structural specificity using this approach.

  18. Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies.

    PubMed

    Kwiatek, Anna; Mielke, Zofia

    2015-01-25

    A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(2p,2d) study of pyridoxal was performed. The calculations resulted in five stable PLHB conformers stabilized by intramolecular O-H⋯O bonding between phenolic OH and carbonyl C=O groups and another thirteen conformers in which OH or/and aldehyde groups are rotated by 180° around CO or/and CC bonds leading, respectively, to formation of PLO, PLA and PLOA conformers. The analysis of the spectra of the as-deposited matrix indicated that two most stable PLHB1 and PLHB2 conformers with intramolecular hydrogen bond are present in the matrix. The exposure of the PL/Ar matrix to mercury lamp radiation (λ>345 nm) induced conformational change of PLHB isomers to PLOA ones.

  19. Mariner Jupiter/Saturn 1977 infrared interferometer spectrometer (MJS' 77) design study

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A design study of the Infrared Interferometer Spectrometer and Radiometer (IRIS) instrument for the Mariner Jupiter/Saturn 1977 mission was conducted. The objective of the study was to investigate a number a potential problem areas identified in previous studies and to develop the instrument system designs along the lines providing for the optimum performance obtainable with the allowable budgets. The considerations for the optical design, mechanical design, and electronic design are examined.

  20. Studying soil properties using visible and near infrared spectral analysis

    NASA Astrophysics Data System (ADS)

    Moretti, S.; Garfagnoli, F.; Innocenti, L.; Chiarantini, L.

    2009-04-01

    This research is carried out inside the DIGISOIL Project, whose purposes are the integration and improvement of in situ and proximal measurement technologies, for the assessment of soil properties and soil degradation indicators, going form the sensing technologies to their integration and their application in digital soil mapping. The study area is located in the Virginio river basin, about 30 km south of Firenze, in the Chianti area, where soils with agricultural suitability have a high economic value connected to the production of internationally famous wines and olive oils. The most common soil threats, such as erosion and landslide, may determine huge economic losses, which must be considered in farming management practices. This basin has a length of about 23 km for a basin area of around 60,3 Km2. Geological formations outcropping in the area are Pliocene to Pleistocene marine and lacustrine sediments in beds with almost horizontal bedding. Vineyards, olive groves and annual crops are the main types of land use. A typical Mediterranean climate prevails with a dry summer followed by intense and sometimes prolonged rainfall in autumn, decreasing in winter. In this study, three types of VNIR and SWIR techniques, operating at different scales and in different environments (laboratory spectroscopy, portable field spectroscopy) are integrated to rapidly quantify various soil characteristics, in order to acquire data for assessing the risk of occurrence for typically agricultural practice-related soil threats (swelling, compaction, erosion, landslides, organic matter decline, ect.) and to collect ground data in order to build up a spectral library to be used in image analysis from air-borne and satellite sensors. Difficulties encountered in imaging spectroscopy, such as influence of measurements conditions, atmospheric attenuation, scene dependency and sampling representation are investigated and mathematical pre-treatments, using proper algorithms, are applied and

  1. Development of infrared interferometry for upper atmospheric emission studies.

    PubMed

    Baker, D; Steed, A; Stair, A T

    1981-05-15

    This paper is a review of the historical development of the Michelson interferometer into modern-day Fourier transform spectrometry (FTS) used for upper atmospheric emission studies in the near IR. For the period of the last decade, the focus of the review is upon USAF/USU interferometric instruments. Michelson invented the "cross beam" interferometer in 1880; however, the first interferogram was not reported until that of Wood in 1911. Fellgett deduced the multiplex advantage in 1949. By the early 1950s, both Jacqui-not and Rupert had pointed out the throughput advantage, and Fellgett and Strong had each obtained Fourier transforms of interferograms. In 1959, J. Connes and Gush obtained a spectrum of the nighttime IR airglow in 30 min using a Michelson interferometer. In 1962 Gush and Buijs flew an interferometer aboard a balloon to obtain spectra from the airglow. Mertz and M. Block developed a commercial Michelson interferometer in about 1959. L. Block of AFCRL flew a Michelson interferometer aboard a satellite in 1962. In 1965, Connes and Connes obtained high-resolution spectra of planets using cat's-eye retroreflectors coupled with an interferometrically controlled step and integrate method. NASA successfully flew an interferometer aboard a satellite in 1969, which led to including FTS experiments on the planetary probes. In 1965 Tukey and Cooley published their FFT computer program based upon the algorithm of Good. AFGL/USU applied the FFT algorithm to FTS that same year. Stair launched a rocketborne liquid-He cooled interferometer in 1976 which obtained spectra of earth limb emissions. Mertz in 1959 approached field-of-view widening of an interferometer using variable thickness glass compensator plates. Baker and his USU staff used the Connes-Bouchareine compensation method to develop a series of wide-angle Michelson interferometers (WAMIs) for airglow and auroral studies. In 1973, they created a cryogenic WAMI to obtain an IR airglow spectrum in only 10 sec

  2. A far-infrared radiometer to study optically thin ice clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Libois, Q.; Ivanescu, L.; Blanchet, J. P.; Barbero, F.; Laurence, C.; Pelletier, L. S.; Proulx, C.; Dejmek, M.

    2015-12-01

    The water cycle in the dry and cold Arctic is not well understood. In particular, ice clouds, which play a significant role in the radiative budget of this region, are poorly known. In addition to filling a gap in cloud observation at high latitudes, the deployment of CALIPSO and CloudSat satellites also highlighted the ubiquity of optically thin ice clouds during the polar night in the Arctic. These clouds can significantly alter the amount of far infrared radiation escaping the Earth, and consequently the temperatures in the upper atmosphere. Since their signature in the far infrared is also very sensitive to their microphysical properties (crystals size and shape) and optical depth, these quantities can be retrieved from satellite observations. Such measurements in the far infrared (particularly beyond 30 μm), were until recently constrained by technical limitations, but recent advancements in micro-bolometers technology at INO (Québec) has allowed to study this under-explored spectral region. In this context, a satellite mission dedicated to studying thin ice clouds in the Arctic (TICFIRE) is under review at the Canadian Space Agency. We present here the Far InfraRed Radiometer (FIRR), which is meant to be a breadboard for the future satellite instrument. The FIRR measures atmospheric radiation in 9 spectral bands extending from 8 to 50 μm. After characterization in the laboratory, it was operated from the ground under various atmospheric conditions. These measurements were successfully compared to radiative transfer simulations, pointing out the potential of the FIRR to detect ice clouds and to measure low water vapor contents. In April 2015, the FIRR was operated on board an aircraft during the pan-arctic NETCARE campaign. It was looking downward to mimic satellite observations, which is to our knowledge a first in the far infrared. Simultaneously, atmospheric profiles and clouds microphysical properties were measured by probes mounted on the same aircraft

  3. Picosecond laser cutting and drilling of thin flex glass

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, Krystian L.; Brunton, Adam; Rumsby, Phil; Hand, Duncan P.

    2016-03-01

    We investigate the feasibility of cutting and drilling thin flex glass (TFG) substrates using a picosecond laser operating at wavelengths of 1030 nm, 515 nm and 343 nm. 50 μm and 100 μm thick AF32®Eco Thin Glass (Schott AG) sheets are used. The laser processing parameters such as the wavelength, pulse energy, pulse repetition frequency, scan speed and the number of laser passes which are necessary to perform through a cut or to drill a borehole in the TFG substrate are studied in detail. Our results show that the highest effective cutting speeds (220 mm/s for a 50 μm thick TFG substrate and 74 mm/s for a 100 μm thick TFG substrate) are obtained with the 1030 nm wavelength, whereas the 343 nm wavelength provides the best quality cuts. The 515 nm wavelength, meanwhile, can be used to provide relatively good laser cut quality with heat affected zones (HAZ) of <25 μm for 50 μm TFG and <40 μm for 100 μm TFG with cutting speeds of 100 mm/s and 28.5 mm/s, respectively. The 343 nm and 515 nm wavelengths can also be used for drilling micro-holes (with inlet diameters of ⩽75 μm) in the 100 μm TFG substrate with speeds of up to 2 holes per second (using 343 nm) and 8 holes per second (using 515 nm). Optical microscope and SEM images of the cuts and micro-holes are presented.

  4. Picosecond time scale modification of forward scattered light induced by absorption inside particles.

    PubMed

    Kervella, Myriam; d'Abzac, Françoix-Xavier; Hache, François; Hespel, Laurent; Dartigalongue, Thibault

    2012-01-01

    The aim of this work is to evaluate the influence of absorption processes on the Time Of Flight (TOF) of the light scattered out of a thick medium in the forward direction. We use a Monte-Carlo simulation with temporal phase function and Debye modes. The main result of our study is that absorption inside the particle induces a decrease of the TOF on a picosecond time scale, measurable with a femtosecond laser apparatus. This decrease, which exhibits a neat sensitivity to the absorption coefficient of particles, could provide an efficient way to measure this absorption.

  5. Spur decay of the solvated electron in picosecond radiolysis measured with time-correlated absorption spectroscopy

    SciTech Connect

    Bartels, D.M.; Cook, A.R.; Mudaliar, M.; Jonah, C.D.

    2000-03-02

    Spur decay kinetics of the hydrated electron following picosecond pulse radiolysis of water have been measured using a time-correlated transient absorption technique with an asynchronous mode-locked laser. The 11 ns time window afforded by this signal-averaging technique is ideal to match up with more conventional transient absorption measurements taken to microsecond time scales. The precise data recorded in this study require a revision downward of the time zero solvated electron yield to approximately 4.0 per 100 eV of energy absorbed, to match the best available scavenger product measurements.

  6. Si nanostructures grown by picosecond high repetition rate pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Pervolaraki, M.; Komninou, Ph.; Kioseoglou, J.; Athanasopoulos, G. I.; Giapintzakis, J.

    2013-08-01

    One-step growth of n-doped Si nanostructures by picosecond ultra fast pulsed laser deposition at 1064 nm is reported for the first time. The structure and morphology of the Si nanostructures were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Transmission electron microscopy studies revealed that the shape of the Si nanostructures depends on the ambient argon pressure. Fibrous networks, cauliflower formations and Si rectangular crystals grew when argon pressure of 300 Pa, 30 Pa and vacuum (10-3 Pa) conditions were used, respectively. In addition, the electrical resistance of the vacuum made material was investigated.

  7. Ion acceleration in a solitary wave by an intense picosecond laser pulse.

    PubMed

    Zhidkov, A; Uesaka, M; Sasaki, A; Daido, H

    2002-11-18

    Acceleration of ions in a solitary wave produced by shock-wave decay in a plasma slab irradiated by an intense picosecond laser pulse is studied via particle-in-cell simulation. Instead of exponential distribution as in known mechanisms of ion acceleration from the target surface, these ions accelerated forwardly form a bunch with relatively low energy spread. The bunch is shown to be a solitary wave moving over expanding plasma; its velocity can exceed the maximal velocity of ions accelerated forward from the rear side of the target.

  8. Infrared diode laser study of the hydrogen bifluoride anion FHF(-) and FDF(-)

    NASA Astrophysics Data System (ADS)

    Kawaguchi, K.; Hirota, E.

    1986-03-01

    In connection with certain difficulties, no infrared spectroscopic studies of anions in discharge plasmas have been reported until the recent observations of the OH(-) vibration-rotation spectrum by Owrutsky et al. (1985). The present paper is concerned with observations regarding the vibration-rotation spectrum of the hydrogen bifluoride anion. The FHF(-) ion has played an important part in the study of the hydrogen bond. The high-resolution infrared study reported in this paper gives precise information about the molecular structure and vibrational frequencies of the anion. It is pointed out that the frequency shift between the gas phase and the solid phase, especially observed in the nu-3 band, will be useful to estimate intermolecular forces in the solid phase. Attention is given to the experiments, the observed spectra and the analysis, the velocity modulated spectrum and identification of molecular species, the vibrational assignments for FHF(-), and the spectrum of FDF(-).

  9. Rheo-attenuated total reflectance infrared spectroscopy: a new tool to study biopolymers.

    PubMed

    Boulet-Audet, Maxime; Vollrath, Fritz; Holland, Chris

    2011-03-01

    Whilst rheology is the reference technique to study the mechanical properties of unspun silk, we know little of the structure and the dynamics that generate them. By coupling infrared spectroscopy and shearing forces to study silk fibroin conversion, we are introducing a novel tool to address this gap in our knowledge. Here the silk conversion process has been studied dynamically using polarized attenuated total reflectance Fourier transform infrared spectroscopy whilst applying shear, thus revealing silk protein conformation and molecular orientation in situ. Our results show that the silk conversion process starts with a pre-alignment of the proteins followed by a rapid growth of the β-sheet formation and then a subsequent deceleration of the growth. We propose that this tool will provide further insight into not only silk but any biopolymer solution, opening a new window into biological materials.

  10. Preliminary study on diffuse axonal injury by Fourier transform infrared spectroscopy histopathology imaging.

    PubMed

    Yang, Tiantong; He, Guanglong; Zhang, Xiang; Chang, Lin; Zhang, Haidong; Ripple, Mary G; Fowler, David R; Li, Ling

    2014-01-01

    The objective of this study was to evaluate the application of Fourier transform infrared (FTIR) spectroscopy for detecting diffuse axonal injury (DAI) in a mouse model. Brain tissues from DAI mouse model were prepared with H&E, silver, and β-amyloid precursor protein (β-APP) immunohistochemistry stains and were also studied with FTIR. The infrared spectrum images showed high absorption of amide II in the subcortical white matter of the experimental mouse brain, while there was no obvious expression of amide II in the control mouse brain. The areas with high absorption of amide II were in the same distribution as the DAI region confirmed by the silver and β-APP studies. The result suggests that high absorption of amide II correlates with axonal injury. The use of FTIR imaging allows the biochemical changes associated with DAI pathologies to be detected in the tissues, thus providing an important adjunct method to the current conventional pathological diagnostic techniques.

  11. [Study on estimation of deserts soil total phosphorus content from thermal-infrared emissivity].

    PubMed

    Hou, Yan-jun; Tiyip, Tashpolat; Zhang, Fei; Sawut, Mamat; Nurmemet, Ilyas

    2015-02-01

    Soil phosphorus provides nutrient elements for plants, is one of important parameters for evaluating soil quality. The traditional method for soil total phosphorus content (STPC) measurement is not effective and time-consuming. However, remote sensing (RS) enables us to determine STPC in a fast and efficient way. Studies on the estimation of STPC in near-infrared spectroscopy have been developed by scholars, but model accuracy is still poor due to the low absorption coefficient and unclear absorption peak of soil phosphorus in near-infrared. In order to solve the deficiency which thermal-infrared emissivity estimate desert soil total phosphorus content, and could improve precision of estimation deserts soil total phosphorus. In this paper, characteristics of soil thermal-infrared emissivity are analyzed on the basis of laboratory processing and spectral measurement of deserts soil samples from the eastern Junggar Basin. Furthermore, thermal-infrared emissivity based RS models for STPC estimation are established and accuracy assessed. Results show that: when STPC is higher than 0.200 g x kg(-1), the thermal-infrared emissivity increases with the increase of STPC on the wavelength between 8.00 microm and 13 microm, and the emissivity is more sensitive to STPC on the wavelength between 9.00 and 9.6 microm; the estimate mode based on multiple stepwise regression was could not to estimate deserts soil total phosphorus content from thermal-infrared emissivity because the estimation effects of them were poor. The estimation accuracy of model based on partial least squares regression is higher than the model based on multiple stepwise regression. However, the accuracy of second-order differential estimation model based on partial least square regression is higher than based on multiple stepwise regression; The first differential of continuous remove estimation model based on partial least squares regression is the best model with R2 of correction and verification are up to

  12. Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy.

    PubMed

    Huber, A J; Ocelic, N; Hillenbrand, R

    2008-03-01

    We demonstrate that mid-infrared surface phonon polariton excitation, propagation and interference can be studied by scattering-type near-field optical microscopy (s-SNOM). In our experiments we image surface phonon polaritons (SPPs) propagating on flat SiC crystals. They are excited by weakly focused illumination of single or closely spaced metal disks we fabricated on the SiC surface by conventional photolithography. SPP imaging is performed by pseudo-heterodyne interferometric detection of infrared light scattered by the metal tip of our s-SNOM. The pseudo-heterodyne technique simultaneously yields optical amplitude and phase images which allows us to measure the SPP wave vector--including its sign--and the propagation length and further to study SPP interference. High resolution imaging of SPPs could be applied to investigate for example SPP focusing or heat transfer by SPPs in low dimensional nanostructures.

  13. Initial Technology Assessment for the Large UV-Optical-Infrared (LUVOIR) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Feinberg, Lee D.; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-01-01

    The NASA Astrophysics Divisions 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet-optical-infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for bio-signatures via direct-imaging and spectroscopic characterization of habitable exo-planets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV-Optical Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  14. An infrared spectroscopic study of H-bond network in hyperbranched polyester polyol

    NASA Astrophysics Data System (ADS)

    Žagar, Ema; Grdadolnik, Jože

    2003-10-01

    A FTIR study of aliphatic hyperbranched polyester of the fourth generation Boltorn H40 (BH40) is presented. In order to properly assign the main vibrational bands in infrared spectrum temperature measurements, hydration and H/D exchange experiments were performed. Beside these experiments, difference spectroscopy, 2D generalized correlation infrared spectroscopy (2-DGCS) and band fitting procedure were employed to study the main interactions in polymer. On the basis of the detected interactions between various groups the structure of a H-bond network in hyperbranched polyester is proposed. Three main H-bond interactions were detected. Besides CO⋯HO and HO⋯HO a third type of H-bond is present (CO⋯HO⋯HO). A minor type of interactions represent the hydrogen bond formed with the carboxyl COOH group and impurities, which may be present in lower concentration.

  15. Initial technology assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) mission concept study

    NASA Astrophysics Data System (ADS)

    Bolcar, Matthew R.; Feinberg, Lee; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-07-01

    The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  16. An investigation of model forensic bone in soil environments studied using infrared spectroscopy.

    PubMed

    Howes, Johanna M; Stuart, Barbara H; Thomas, Paul S; Raja, Sophil; O'Brien, Christopher

    2012-09-01

    Infrared spectroscopy has been used to examine changes to bone chemistry as a result of soil burial. Pig carcasses were buried as part of a controlled field study, and pig bone was used in soil environments established in the laboratory. The variables of species type, bone pretreatment, soil type and pH, moisture content, temperature, and burial time were investigated. The crystallinity index (CI) and the organic and carbonate contents of the bones were monitored. The data revealed decreasing trends in the organic and carbonate contents and an increase in the CI of the bone with burial time. An acidic soil environment and soil type are the factors that have the most influence on bone chemistry as a result of burial. The study demonstrates the potential of infrared spectroscopy as a straightforward method of monitoring the changes associated with aging of bones in a variety of soil environments.

  17. Initial Technology Assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Feinberg, Lee; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-01-01

    The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  18. Study on probability of detection for fatigue cracks in sonic infrared imaging

    NASA Astrophysics Data System (ADS)

    Zhu, Jun-zhen; Zhang, Chao-sheng; Feng, Fu-zhou; Min, Qing-xu; Xu, Chao

    2016-07-01

    Detection reliability of sonic infrared imaging is one of the increasingly important aspects for out of lab applications. And for the detection reliability evaluation, probability of detection (POD) for different defects under given test conditions has been successfully used as an accepted quantitative measurement. In this study, we test a set of C45 ferritic steel plates with artificial fatigue cracks. Experimental results show that the crack heating response increases with the increasing crack length, and the relationship between the logarithmic form of heat response signal and the crack length appears to be linear. Based on the above statistic characteristics, the linear regression analysis and the Wald method are adopted to estimate the POD function and its confidence interval. The study aims to provide a quantitative evaluation method for detection reliability in sonic infrared imaging.

  19. Study of optical techniques for the Ames unitary wind tunnel. Part 5: Infrared imagery

    NASA Technical Reports Server (NTRS)

    Lee, George

    1992-01-01

    A survey of infrared thermography for aerodynamics was made. Particular attention was paid to boundary layer transition detection. IR thermography flow visualization of 2-D and 3-D separation was surveyed. Heat transfer measurements and surface temperature measurements were also covered. Comparisons of several commercial IR cameras were made. The use of a recently purchased IR camera in the Ames Unitary Plan Wind Tunnels was studied. Optical access for these facilities and the methods to scan typical models was investigated.

  20. Picosecond X-ray streak camera dynamic range measurement

    NASA Astrophysics Data System (ADS)

    Zuber, C.; Bazzoli, S.; Brunel, P.; Fronty, J.-P.; Gontier, D.; Goulmy, C.; Raimbourg, J.; Rubbelynck, C.; Trosseille, C.

    2016-09-01

    Streak cameras are widely used to record the spatio-temporal evolution of laser-induced plasma. A prototype of picosecond X-ray streak camera has been developed and tested by Commissariat à l'Énergie Atomique et aux Énergies Alternatives to answer the Laser MegaJoule specific needs. The dynamic range of this instrument is measured with picosecond X-ray pulses generated by the interaction of a laser beam and a copper target. The required value of 100 is reached only in the configurations combining the slowest sweeping speed and optimization of the streak tube electron throughput by an appropriate choice of high voltages applied to its electrodes.

  1. Heterodyne picosecond thermoreflectance applied to nanoscale thermal metrology

    NASA Astrophysics Data System (ADS)

    Dilhaire, S.; Pernot, G.; Calbris, G.; Rampnoux, J. M.; Grauby, S.

    2011-12-01

    Picosecond thermoreflectance is an unprecedented powerful technique for nanoscale heat transfer analysis and metrology, but different sources of artifacts were reported in the literature making this technique difficult to use for long delay (several ns) thermal analysis. We present in this paper a new heterodyne picosecond thermoreflectance (HPTR) technique. As it uses two slightly frequency shifted lasers instead of a mechanical translation stage, it is possible to avoid all artifacts leading to erroneous thermal parameter identifications. The principle and set-up are described as well as the model. The signal delivered by the HPTR experiment is calculated for each excitation configurations, modulating or not the pump beam. We demonstrate the accuracy of the technique in the identification of the thermal conductivity of a 50 nm thick SiO2 layer. Then, we discuss the role of the modulation frequency for nanoscale heat transfer analysis.

  2. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement.

    PubMed

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-11-01

    A compact multifunctional optical correlator system for pulse width measurement of ultrashort ultraviolet (UV) pulses has been designed and experimentally demonstrated. Both autocorrelation and cross-correlation functions are measured using a single nonlinear crystal, and the switching between two measurements requires no adjustment of phase matching and detector. The system can measure UV pulse widths from sub-picoseconds to 100 ps, and it involves no auxiliary pulse in the measurement. The measurement results on a burst-mode picosecond UV laser show a high-quality performance on speed, accuracy, resolution, and dynamic range. The proposed correlator can be applied to measure any ultrashort UV pulses produced through sum-frequency generation or second-harmonic generation. PMID:25402928

  3. The cosmic infrared background experiment-2 (CIBER-2) for studying the near-infrared extragalactic background light

    NASA Astrophysics Data System (ADS)

    Shirahata, Mai; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha; Enokuchi, Akito; Hristov, Viktor; Kanai, Yoshikazu; Kim, Min Gyu; Korngut, Phillip; Lanz, Alicia; Lee, Dae-Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Morford, Tracy; Ohnishi, Yosuke; Park, Won-Kee; Sano, Kei; Takeyama, Norihide; Tsumura, Kohji; Wada, Takehiko; Wang, Shiang-Yu; Zemcov, Michael

    2016-07-01

    We present the current status of the Cosmic Infrared Background ExpeRiment-2 (CIBER-2) project, whose goal is to make a rocket-borne measurement of the near-infrared Extragalactic Background Light (EBL), under a collaboration with U.S.A., Japan, South Korea, and Taiwan. The EBL is the integrated light of all extragalactic sources of emission back to the early Universe. At near-infrared wavelengths, measurement of the EBL is a promising way to detect the diffuse light from the first collapsed structures at redshift z˜10, which are impossible to detect as individual sources. However, recently, the intra-halo light (IHL) model is advocated as the main contribution to the EBL, and our new result of the EBL fluctuation from CIBER-1 experiment is also supporting this model. In this model, EBL is contributed by accumulated light from stars in the dark halo regions of low- redshift (z<2) galaxies, those were tidally stripped by the interaction of satellite dwarf galaxies. Thus, in order to understand the origin of the EBL, both the spatial fluctuation observations with multiple wavelength bands and the absolute spectroscopic observations for the EBL are highly required. After the successful initial CIBER- 1 experiment, we are now developing a new instrument CIBER-2, which is comprised of a 28.5-cm aluminum telescope and three broad-band, wide-field imaging cameras. The three wide-field (2.3×2.3 degrees) imaging cameras use the 2K×2K HgCdTe HAWAII-2RG arrays, and cover the optical and near-infrared wavelength range of 0.5-0.9 μm, 1.0-1.4 μm and 1.5-2.0 μm, respectively. Combining a large area telescope with the high sensitivity detectors, CIBER-2 will be able to measure the spatial fluctuations in the EBL at much fainter levels than those detected in previous CIBER-1 experiment. Additionally, we will use a linear variable filter installed just above the detectors so that a measurement of the absolute spectrum of the EBL is also possible. In this paper, the scientific

  4. Photodynamic inactivation of microorganisms which cause pulmonary diseases with infrared light: an in vitro study

    NASA Astrophysics Data System (ADS)

    Leite, Ilaiáli S.; Geralde, Mariana C.; Salina, Ana C.; Medeiros, Alexandra I.; Kurachi, Cristina; Bagnato, Vanderlei S.; Inada, Natalia M.

    2014-03-01

    Lower respiratory infections are among the leading causes of death worldwide. In this study, it was evaluated the interaction of indocyanine green, a photosensitizer activated by infrared light, with alveolar macrophages and the effectiveness of the photodynamic therapy using this compound against Streptococcus pneumoniae . Initial experiments analyzed indocyanine green toxicity to alveolar macrophages in the dark with different drug concentrations and incubation times, and macrophage viability was obtained with the MTT method. The average of the results showed viability values below 90% for the two highest concentrations. Experiments with Streptococcus pneumoniae showed photodynamic inactivation with 10 μM indocyanine green solution. Further experiments with the bacteria in co-culture with AM will be conducted verifying the photodynamic inactivation effectiveness of the tested drug concentrations and incubation periods using infrared light.

  5. Study of wavefront error and polarization of a side mounted infrared window

    NASA Astrophysics Data System (ADS)

    Liu, Jiaguo; Li, Lin; Hu, Xinqi; Yu, Xin

    2008-03-01

    The wavefront error and polarization of a side mounted infrared window made of ZnS are studied. The Infrared windows suffer from temperature gradient and stress during their launch process. Generally, the gradient in temperature changes the refractive index of the material whereas stress produces deformation and birefringence. In this paper, a thermal finite element analysis (FEA) of an IR window is presented. For this purpose, we employed an FEA program Ansys to obtain the time-varying temperature field. The deformation and stress of the window are derived from a structural FEA with the aerodynamic force and the temperature field previously obtained as being the loads. The deformation, temperature field, stress field, ray tracing and Jones Calculus are used to calculate the wavefront error and the change of polarization state.

  6. The Rho Ophiuchi cloud young stellar population - Results of a near-infrared study

    NASA Technical Reports Server (NTRS)

    Greene, Thomas P.; Young, Erick T.

    1991-01-01

    An imaging survey of 1.4 sq pc of the Rho Ophiuchi dark cloud in the J, H, and K near-infrared photometric bands was conducted. Approximately 332 of the 481 detected sources are associated with the cloud, and 30 percent of these have near-infrared excesses, indicative of disks or circumstellar material surrounding these young stellar objects (YSOs). The K-band luminosity function is significantly different in different regions of the survey area, suggesting that YSOs in these regions have different ages or mass functions. The entire survey area has a high star formation efficiency of about 23 percent. Finally, many newly detected sources provide a relatively large, uniformly sensitive sample of objects for study at longer wavelengths to better determine true source luminosities and evolutionary lifetimes.

  7. Optical Design Trade Study for the Wide Field Infrared Survey Telescope [WFIRST

    NASA Technical Reports Server (NTRS)

    Content, David A.; Goullioud, R.; Lehan, John P.; Mentzell, John E.

    2011-01-01

    The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics mission by the Astro2010 Decadal Survey incorporating the Joint Dark Energy Mission (JDEM)-Omega payload concept and multiple science white papers. This mission is based on a space telescope at L2 studying exoplanets [via gravitational microlensing], probing dark energy, and surveying the near infrared sky. Since the release of NWNH, the WFIRST project has been working with the WFIRST science definition team (SDT) to refine mission and payload concepts. We present the driving requirements. The current interim reference mission point design, based on the use of a 1.3m unobscured aperture three mirror anastigmat form, with focal imaging and slitless spectroscopy science channels, is consistent with the requirements, requires no technology development, and out performs the JDEM-Omega design.

  8. X-ray production with sub-picosecond laser pulses

    SciTech Connect

    Schappert, G.T.; Cobble, J.A.; Fulton, R.D.; Kyrala, G.A.

    1993-12-31

    The interaction of intense, sub-picosecond laser pulses with solid targets produces intense picosecond x-ray pulses. With focused laser pulses of several 10 {sup 18} W/cm{sup 2}, He-like and H-like line radiation from targets such as aluminum and silicon has been produced. The energy conversion efficiency from the laser pulse energy to the 1--2 keV line x-rays is nearly one percent. The duration of the line x-ray radiation is of the order of ten picoseconds, although this may be an upper estimate because of the temporal resolution of the x-ray streak camera. The spatial extent of the x-ray source region is only slightly larger than the laser focal spot, or about 10 {mu}m in diameter. With these characteristics, such x-ray sources emit an intensity of nearly 10{sup 14} W/cm{sup 2}. Experiments and modeling which led to the above conclusions will be discussed.

  9. A sensitivity study for far infrared balloon-borne limb emission sounding of stratospheric trace gases

    NASA Astrophysics Data System (ADS)

    Xu, J.; Schreier, F.; Vogt, P.; Doicu, A.; Trautmann, T.

    2013-05-01

    This paper presents a sensitivity study performed for trace gases retrieval from synthetic observations by TELIS (TErahertz and submillimeter LImb Sounder) which is a stratospheric balloon-borne cryogenic heterodyne spectrometer. Issues pertaining to hydroxyl radical (OH) retrieval from the far infrared measurements by the 1.8 THz channel are addressed. The study is conducted by a retrieval code PILS (Profile Inversion for Limb Sounding) developed to solve the nonlinear inverse problems arising in the analysis of infrared/microwave limb sounding measurements. PILS combines a line-by-line forward model with automatic differentiation for computing Jacobians and employs regularized nonlinear least squares inversion. We examine the application of direct and iterative regularization methods and evaluate the performance of single- and multi-profile retrievals. Sensitivities to expected errors in calibration procedure, instrumental knowledge and atmospheric profiles have been analyzed. Nonlinearity effect, inaccurate sideband ratio, and pointing error turned out to be the dominant error sources. Furthermore, the capability of multi-channel simultaneous retrieval from the far infrared and submillimeter data has been investigated. The errors and averaging kernels infer that the quality of the obtained hydrogen chloride (HCl) can be improved by significantly better exploitation of information from the observations.

  10. Structural study of photodegraded acrylic-coated lime wood using Fourier transform infrared and two-dimensional infrared correlation spectroscopy.

    PubMed

    Popescu, Carmen-Mihaela; Simionescu, Bogdan C

    2013-06-01

    The weathering of acrylic films and acrylic-coated lime wood (Tillia cordata Mill.) were examined using Fourier transform infrared (FT-IR) and two-dimensional infrared correlation spectroscopy. The obtained results showed chemical changes induced by exposure to weathering conditions, in both films and coated wood. The observed spectral changes of the acrylic films refer to the absorption band assigned to the C-O stretching, which progressively decreases with increasing exposure time. In the spectra of treated wood samples the main signal indicating the advance of oxidation during the photodegradation exposure is the gradual increase and broadening of the band in the carbonyl region. This is due to the formation of the non-hydrogen bonded aliphatic carboxylic acids and γ-lactone structures in the acrylic resin and of the nonconjugated ketones, carboxyl groups, and lactones in wood. As a consequence, the increase of the 1734 cm(-1) band is due to the degradation of lignin from wood surface. These observations are also supported by the decreased intensities of the bands at 1598 and 1505 cm(-1), assigned to C=C of aromatic skeletal (lignin). The relative intensity of the characteristic aromatic lignin band at 1505 cm(-1) decreases up to 25% of its original value after weathering, being less than half of the value obtained for uncoated wood. Two-dimensional infrared (2D IR) correlation spectroscopy was used to identify the sequence of the modifications of the different stretching vibrations bands under the weathering conditions, the method allowing the prediction of the order of degradation reactions. The acrylic resin degradation starts with the formation of radicals by abstraction of the tertiary hydrogen atoms of the methyl acrylate units and the α-CH3 groups from the ethyl methacrylate units. The subsequent decomposition and oxidation led to the formation of alcohol groups, hydroperoxides, ketones, and/or carboxylic acid groups. The 2D IR correlation spectra of

  11. Nonlinear processes upon two-photon interband picosecond excitation of PbWO4 crystal

    NASA Astrophysics Data System (ADS)

    Lukanin, V. I.; Karasik, A. Ya

    2016-09-01

    A new experimental method is proposed to study the dynamics of nonlinear processes occurring upon two-photon interband picosecond excitation of a lead tungstate crystal and upon its excitation by cw probe radiation in a temporal range from several nanoseconds to several seconds. The method is applied to the case of crystal excitation by a sequence of 25 high-power picosecond pulses with a wavelength of 523.5 nm and 633-nm cw probe radiation. Measuring the probe beam transmittance during crystal excitation, one can investigate the influence of two-photon interband absorption and the thermal nonlinearity of the refractive index on the dynamics of nonlinear processes in a wide range of times (from several nanoseconds to several seconds). The time resolution of the measuring system makes it possible to distinguish fast and slow nonlinear processes of electronic or thermal nature, including the generation of a thermal lens and thermal diffusion. An alternative method is proposed to study the dynamics of induced absorption transformation and, therefore, the dynamics of the development of nonlinear rocesses upon degenerate two-photon excitation of the crystal in the absence of external probe radiation.

  12. OLBERS: An Interplanetary Probe to Study Visible and Infrared Diffuse Backgrounds

    NASA Astrophysics Data System (ADS)

    Désert, F.-X.

    1995-10-01

    The visible extragalactic background (though as yet undetected) is insufficient to explain the abundance of heavy elements in galaxies: either there should be some diffuse extragalactic light in the near infrared (from 1 to 10 μm) and/or in the far infrared (≥100 μm) if dust has reprocessed the star light. We propose a new space mission to be dedicated to the search and mapping of primordial stellar light from the visible to the mid-infrared (20 μm). In this spectrum range, detectors have reached such a sensitivity that the mission should aim at being (source) photon noise limited, and not any longer background photon noise limited. For that purpose, a small passively cooled telescope with large format CCDs and CIDs could be sent beyond the zodiacal dust cloud (which is absent beyond a solar distance of about 3 AU). In that case, the only remaining foregrounds before reaching the extragalactic background, is due to the Milky Way integrated emission from stars and the diffuse galactic light due to scattering and emission by interstellar dust, which are all unavoidable. Maps of the extragalactic light could be obtained at the arcminute resolution with high signal to noise ratio. This mission is the next logical step after IRAS, COBE and ISO for the study of extragalactic IR backgrounds. It has been proposed as a possible medium-sized mission for the post-horizon 2000 ESA program that could be a piggy back of a planetary mission.

  13. Mapping Glacial Weathering Processes with Thermal Infrared Remote Sensing: A Case Study at Robertson Glacier, Canada

    NASA Astrophysics Data System (ADS)

    Rutledge, A. M.; Christensen, P. R.; Shock, E.; Canovas, P. A., III

    2014-12-01

    Geologic weathering processes in cold environments, especially subglacial chemical processes acting on rock and sediment, are not well characterized due to the difficulty of accessing these environments. Glacial weathering of geologic materials contributes to the solute flux in meltwater and provides a potential source of energy to chemotrophic microbes, and is thus an important component to understand. In this study, we use Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data to map the extent of glacial weathering in the front range of the Canadian Rockies using remotely detected infrared spectra. We ground-truth our observations using laboratory infrared spectroscopy, x-ray diffraction, and geochemical analyses of field samples. The major goals of the project are to quantify weathering inputs to the glacial energy budget, and to link in situ sampling with remote sensing capabilities. Robertson Glacier, Alberta, Canada is an excellent field site for this technique as it is easily accessible and its retreating stage allows sampling of fresh subglacial and englacial sediments. Infrared imagery of the region was collected with the ASTER satellite instrument. At that same time, samples of glacially altered rock and sediments were collected on a downstream transect of the glacier and outwash plain. Infrared laboratory spectroscopy and x-ray diffraction were used to determine the composition and abundance of minerals present. Geochemical data were also collected at each location, and ice and water samples were analyzed for major and minor elements. Our initial conclusion is that the majority of the weathering seems to be occurring at the glacier-rock interface rather than in the outwash stream. Results from both laboratory and ASTER data indicate the presence of leached weathering rinds. A general trend of decreasing carbonate abundances with elevation (i.e. residence time in ice) is observed, which is consistent with increasing calcium ion

  14. [The Study on Infrared Spectra of 7-Hydroxycoumarin by Density Functional Theory].

    PubMed

    Jia, Fei-yun; Su, Yu; Ran, Ming; Zhu, Jiang; Zhang, Bo

    2016-01-01

    Infrared spectroscopy is an important source of information for the identification of the compounds structure and it is great significant for biological activity research of natural and organic drug molecules. With the theoretical calculation method is more reasonable and calculation accuracy continues to improve, Theoretical calculate advantage is more obvious in the infrared spectrum simulation and vibration modes attributable identified. And it has important reference value for experimental study of infrared spectral analysis. Using density functional theory, geometry optimizations and frequencies calculation of 7-Hydroxycoumarin were performed at the level of B3LYP/6-311G(d, p), the stable structure and all vibration modes of 7-Hydroxycoumarin were attained. The results show that the infrared absorption peak of 7-hydroxycoumarin is mainly distributed in the several regions in wave number of 3 700-3 500, 3 150-3 000, 1 750-1 400, 1 400-1 000, 1 000-50 cm(-1). In addition to the vibration in a wave number range of 3 700-3 500, 3 150-3 000 cm(-1) is relatively independent, and were attributed to OH stretching vibration and benzene ring CH stretching vibration, the other several vibration regions are more complex, the different degree of spectral peaks is composed of multiple vibration modes. Finally, based on the theoretical analysis of the vibration mode, the vibration modes of 7-Hydroxycoumarin molecule were assigned, and in order to discuss the reliability of theoretical calculation method, the correlation diagram of the main absorption peak of 7-hydroxyl group was drawn from the theoretical value of X axis and the experimental value of Y axis, the correlation between experimental IR data and calculated IR data of 7-Hydroxycoumarin was analyzed through the linear regression method. Results show that they have good correlation, correlation coefficient values "r" equals 0.998 5, and the theory calculation of 7-Hydroxycoumarin IR by density functional theory at

  15. Triggered infrared spectroscopy for investigating metalloprotein chemistry.

    PubMed

    Vincent, Kylie A

    2010-08-13

    Recent developments in infrared (IR) spectroscopic time resolution, sensitivity and sample manipulation make this technique a powerful addition to the suite of complementary approaches for the study of time-resolved chemistry at metal centres within proteins. Application of IR spectroscopy to proteins has often targeted the amide bands as probes for gross structural change. This article focuses on the possibilities arising from recent IR technical developments for studies that monitor localized vibrational oscillators in proteins--native or exogenous ligands such as NO, CO, SCN(-) or CN(-), or genetically or chemically introduced probes with IR-active vibrations. These report on the electronic and coordination state of metals, the kinetics, intermediates and reaction pathways of ligand release, hydrogen-bonding interactions between the protein and IR probe, and the electrostatic character of sites in a protein. Metalloprotein reactions can be triggered by light/dark transitions, an electrochemical step, a change in solute composition or equilibration with a new gas atmosphere, and spectra can be obtained over a range of time domains as far as the sub-picosecond level. We can expect to see IR spectroscopy exploited, alongside other spectroscopies, and crystallography, to elucidate reactions of a wide range of metalloprotein chemistry with relevance to cell metabolism, health and energy catalysis.

  16. Mapping soil surface macropores using infrared thermography: an exploratory laboratory study.

    PubMed

    de Lima, João L M P; Abrantes, João R C B; Silva, Valdemir P; de Lima, M Isabel P; Montenegro, Abelardo A A

    2014-01-01

    Macropores and water flow in soils and substrates are complex and are related to topics like preferential flow, nonequilibrium flow, and dual-continuum. Hence, the quantification of the number of macropores and the determination of their geometry are expected to provide a better understanding on the effects of pores on the soil's physical and hydraulic properties. This exploratory study aimed at evaluating the potential of using infrared thermography for mapping macroporosity at the soil surface and estimating the number and size of such macropores. The presented technique was applied to a small scale study (laboratory soil flume). PMID:25371915

  17. Diffraction of picosecond bulk longitudinal and shear waves in micron thick films

    NASA Astrophysics Data System (ADS)

    Audoin, B.; Perton, M.; Chigarev, N.; Rossignol, C.

    2008-01-01

    Investigation of thin metallic film properties by means of picosecond ultrasonics [C. Thomsen et al., Phys. Rev. Lett. 53, 989 (1984)] has been under the scope of several studies. Generation of longitudinal and shear waves [T. Pézeril et al., Phys. Rev. B 73, 132301 (2006); O. Matsuda et al., Phys. Rev. Lett. 93, 095501 (2004)] with a wave vector normal to the film free surface has been demonstrated. Such measurements cannot provide complete information about properties of anisotropic films. Extreme focusing of a laser pump beam (≈0.5 μm) on the sample surface has recently allowed us to provide evidence of picosecond acoustic diffraction in thin metallic films (≈1 μm) [C. Rossignol et al., Phys. Rev. Lett. 94, 166106 (2005)]. The resulting longitudinal and shear wavefronts propagate at group velocity through the bulk of the film. To interpret the received signals, source directivity diagrams are calculated taking into account material anisotropy, optical penetration, and laser beam width on the sample surface. It is shown that acoustic diffraction increases with optical penetration, so competing with the increasing of directivity caused by beam width. Reflection with mode conversion at the film-substrate interface is discussed.

  18. Production of picosecond, kilojoule, petawatt laser pulses via Raman amplification of nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Trines, R.; Bingham, R.; Norreys, P.; Fiúza, F.; Fonseca, R. A.; Silva, L. O.; Cairns, R. A.

    2011-10-01

    The demonstration of fast-ignition (FI) inertial confinement fusion (ICF) requires the delivery of 40 kJ - 100 kJ of laser energy to the hot spot within 16 ps. In addition, third harmonic conversion to 351 nm is needed to optimize Iλ2 to obtain the correct hot electron energy. High-energy picosecond petawatt beams at 351 nm are difficult to generate using conventional solid-state laser systems. Previous studies of Raman amplification concentrated on maximizing the intensity and power of femtosecond pulses [Trines et al., Nature Physics (2010)]. Here we present particle-in-cell simulations and analytic theory that confirm that Raman amplification of high-energy nanosecond pulses in plasma can generate petawatt peak power pulses of picosecond duration with high efficiency (up to 60%), even at 351 nm wavelength. This scheme provides a potential new route for the realization of fast ignition ICF in the laboratory, as well as access to wide range of other high energy density physics research applications. This work was supported by STFC's CLF and CfFP, by EPSRC through grant EP/G04239X/1 and by FCT (Portugal) through grants PTDC/FIS/66823/2006 and SFRH/BD/38952/2007.

  19. Observation of picosecond superfluorescent pulses in rubidium atomic vapor pumped by 100-fs laser pulses

    SciTech Connect

    Ariunbold, Gombojav O.; Kash, Michael M.; Sautenkov, Vladimir A.; Li, Hebin; Welch, George R.; Rostovtsev, Yuri V.; Scully, Marlan O.

    2010-10-15

    We study the superfluorescence (SF) from a gas of rubidium atoms. The atoms of a dense vapor are excited to the 5D state from the 5S state by a two-photon process driven by 100-fs laser pulses. The atoms decay to the 6P state and then to the 5S state. The SF emission at 420 nm on the 6P-5S transition is recorded by a streak camera with picosecond time resolution. The time duration of the generated SF is tens of picoseconds, which is much shorter than the time scale of the usual relaxation processes, including spontaneous emission and atomic coherence dephasing. The dependence of the time delay between the reference input pulse and SF is measured as a function of laser power. The experimental data are described quantitatively by a simulation based on the semiclassical atom-field interaction theory. The observed change in scaling laws for the peak intensity and delay time can be elucidated by an SF theory in which the sample length is larger than the cooperation length.

  20. Selective ablation of thin films in latest generation CIGS solar cells with picosecond pulses

    NASA Astrophysics Data System (ADS)

    Burn, Andreas; Romano, Valerio; Muralt, Martin; Witte, Reiner; Frei, Bruno; Bücheler, Stephan; Nishiwaki, Shiro

    2012-03-01

    Recent developments in Cu(In,Ga)Se2 (CIGS) thin film photovoltaics enabled the manufacturers to produce highly efficient solar modules. Nevertheless, the production process still lacks a competitive process for module patterning. Today, the industry standard for the serial interconnection of cells is still based on mechanical scribing for the P2 and P3 process. A reduction of the non-productive "dead zone" between the P1 and P3 scribes is crucial for further increasing module efficiency. Compact and affordable picosecond pulsed laser sources are promising tools towards all-laser scribing of CIGS solar modules. We conducted an extensive parameter study comprising picosecond laser sources from 355 to 1064 nm wavelength and 10 to 50 ps pulse duration. Scribing results were analyzed by laser scanning microscope, scanning electron microscope and energy dispersive X-ray spectroscopy. We developed stable and reliable processes for the P1, P2 and P3 scribe. The best parameter sets were then used for the production of functional mini-modules. For comparison, the same was done for a selection of nanosecond pulsed lasers. Standardized analysis of the modules has shown superior electrical performance of the interconnections and confirmed the feasibility of a dead zone width of less than 200 ìm on an entire mini module.

  1. Nanoparticles based laser-induced surface structures formation on mesoporous silicon by picosecond laser beam interaction

    NASA Astrophysics Data System (ADS)

    Talbi, A.; Petit, A.; Melhem, A.; Stolz, A.; Boulmer-Leborgne, C.; Gautier, G.; Defforge, T.; Semmar, N.

    2016-06-01

    In this study, laser induced periodic surface structures were formed on mesoporous silicon by irradiation of Nd:YAG picosecond pulsed laser beam at 266 nm wavelength at 1 Hz repetition rate and with 42 ps pulse duration. The effects of laser processing parameters as laser beam fluence and laser pulse number on the formation of ripples were investigated. Scanning electron microscopy and atomic force microscopy were used to image the surface morphologies and the cross section of samples after laser irradiation. At relatively low fluence ∼20 mJ/cm2, ripples with period close to the laser beam wavelength (266 nm) and with an always controlled orientation (perpendicular to the polarization of ps laser beam) appeared after a large laser pulse number of 12,000. It has been found that an initial random distribution of SiOx nanoparticles is periodically structured with an increase of the laser pulse number. Finally, it is experimentally demonstrated that we formed a 100 nm liquid phase under the protusion zones including the pores in the picosecond regime.

  2. A switchable femtosecond and picosecond soliton fiber laser mode-locked by carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Chuang; Zhang, Chunmin

    2015-07-01

    We propose a switchable dual-scale nanotube-mode-locking fiber laser based on a fiber loop mirror and fiber Bragg grating. The loop mirror not only works as a broadband reflector, but also a birefringence-induced filter. By adjusting the polarization controller in the loop, the operation wavelength can be switched between 1530 and 1560 nm. The femtosecond soliton at 1560 nm has a bandwidth of 5.5 nm and pulse duration of 680 fs, while the picosecond soliton is centered at 1529.5 nm with the bandwidth of 0.11 nm and pulse duration of 23.3 ps. The dual-scale solitons display more than 30 times a difference of pulse width, as well as distinct spectral bandwidth, repetition rate, and pulse energy. Our study provides the flexibly switchable ultrashort pulse sources at femtosecond and picosecond scales, which are suitable for practical applications.

  3. Near-infrared spectroscopy as an auxiliary tool in the study of child development

    PubMed Central

    de Oliveira, Suelen Rosa; Machado, Ana Carolina Cabral de Paula; de Miranda, Débora Marques; Campos, Flávio dos Santos; Ribeiro, Cristina Oliveira; Magalhães, Lívia de Castro; Bouzada, Maria Cândida Ferrarez

    2015-01-01

    OBJECTIVE: To investigate the applicability of Near-Infrared Spectroscopy (NIRS) for cortical hemodynamic assessment tool as an aid in the study of child development. DATA SOURCE: Search was conducted in the PubMed and Lilacs databases using the following keywords: ''psychomotor performance/child development/growth and development/neurodevelopment/spectroscopy/near-infrared'' and their equivalents in Portuguese and Spanish. The review was performed according to criteria established by Cochrane and search was limited to 2003 to 2013. English, Portuguese and Spanish were included in the search. DATA SYNTHESIS: Of the 484 articles, 19 were selected: 17 cross-sectional and two longitudinal studies, published in non-Brazilian journals. The analyzed articles were grouped in functional and non-functional studies of child development. Functional studies addressed the object processing, social skills development, language and cognitive development. Non-functional studies discussed the relationship between cerebral oxygen saturation and neurological outcomes, and the comparison between the cortical hemodynamic response of preterm and term newborns. CONCLUSIONS: NIRS has become an increasingly feasible alternative and a potentially useful technique for studying functional activity of the infant brain. PMID:25862295

  4. Picosecond pulses compression at 1053-nm center wavelength by using a gas-filled hollow-core fiber compressor

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Yuan; Wang, Ding; Leng, Yu-Xin; Dai, Ye

    2015-01-01

    We theoretically study the nonlinear compression of picosecond pulses with 10-mJ of input energy at the 1053-nm center wavelength by using a one-meter-long gas-filled hollow-core fiber (HCF) compressor and considering the third-order dispersion (TOD) effect. It is found that when the input pulse is about 1 ps/10 mJ, it can be compressed down to less than 20 fs with a high transmission efficiency. The gas for optimal compression is krypton gas which is filled in a HCF with a 400-μm inner diameter. When the input pulse duration is increased to 5 ps, it can also be compressed down to less than 100 fs efficiently under proper conditions. The results show that the TOD effect has little impact on picosecond pulse compression and the HCF compressor can be applied on compressing picosecond pulses efficiently with a high compression ratio, which will benefit the research of high-field laser physics. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204328, 61221064, 61078037, 11127901, and 11134010), the National Basic Research Program of China (Grant No. 2011CB808101), the Commission of Science and Technology of Shanghai, China (Grant No. 12dz1100700), the Natural Science Foundation of Shanghai, China (Grant No. 13ZR1414800), and the International Science and Technology Cooperation Program of China (Grant No. 2011DFA11300).

  5. Infrared fiber optic evanescent wave spectroscopy for the study of diffusion in the human skin

    NASA Astrophysics Data System (ADS)

    Raichlin, Yosef; Goldberg, I.; Brenner, Sarah; Shulzinger, Evgeny; Katzir, Abraham

    2002-03-01

    Fourier Transform Infrared (FTIR) spectroscopic systems make use of Attenuated Total Reflection (ATR) elements for the study of skin in dermatology. FTIR - ATR allows real time and reagent-less analysis of several components, simultaneously. The potential for skin studies is increased by the development of the flexible fiber optic sensor made from infrared transparent polycrystalline silver halide. Segments of fibers can replace the ATR sensing elements inside an FTIR system. Moreover a Fiberoptic Evanescent Wave Spectroscopy (FEWS) can also be used for real time in vivo measurement on skin, in situ. We used FEWS to study the diffusion of UV sunscreen lotions from the outer skin layer into the dermis and epidermis, and used the various absorption bands to differentiate between the behavior of the organic and the water molecules in the lotion. FEWS can be a powerful tool for studying the transport of drugs and cosmetic creams through the skin from the stratum corneum to the dermis and epidermis and for studying the lateral diffusion of various molecules into the skin, in vivo and in real time.

  6. The study of a single BGC823 cell using Fourier transform infrared microspectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Qi, Zeming; Wang, Shengyi; Liu, Gang; Gao, Helong; Tian, Yangchao

    2011-09-01

    In order to investigate gastric cancer at cellular and sub-cellular level, a single human gastric adenocarcinoma BGC823 cell was studied by an infrared microscope equipped with a focal plane array (FPA) detector. The spectra showed difference between the nucleus and the endoplasmic reticulum (ER) of the BGC823 cell. The peak of v asPO 2- was shifted to a higher wavenumber at the nucleus compared with that at the ER. The height ratios of 2954 cm -1/2922 cm -1 (CH 3/CH 2) and 1088 cm -1/1539 cm -1 (DNA/amide II) of the nucleus were significantly higher than those of the ER. Furthermore, chemical images reveal the intensity distributions of lipids, proteins and DNA of the single BGC823 cell, and the intense absorptions of proteins and DNA were observed in the nuclear region of the cell while the intense absorption of lipids was found in the ER region of the cell. The Fourier transform infrared (FTIR) microspectroscopic imaging result indicates the study of the single gastric cancer cell at sub-cellular level can be beneficial for knowing gastric cancer more which will be of great importance for the study and diagnosis of gastric cancer. The result also suggests that FPA is a useful tool in the study of a single cell and may be a powerful tool for study and diagnosis of gastric cancer.

  7. 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…

  8. Infrared study of the metal-insulator transition regime in vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Qazilbash, M. M.; Chae, B. G.; Kim, H. T.; Basov, D. N.

    2007-03-01

    Vanadium dioxide (VO2) undergoes a metal-insulator transition at Tc 340 K. The transition region of a VO2 film has been studied with infrared ellipsometry and near-normal incidence reflectance between 40 cm-1 and 5000 cm-1. The measured optical constants are compared to calculations based on effective medium theories. The anomalies in the frequency and temperature dependence of the optical constants will be presented. The implications of the data for the mechanism of the metal-insulator transition will be discussed.

  9. Vibrational structure of the polyunsaturated fatty acids eicosapentaenoic acid and arachidonic acid studied by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kiefer, Johannes; Noack, Kristina; Bartelmess, Juergen; Walter, Christian; Dörnenburg, Heike; Leipertz, Alfred

    2010-02-01

    The spectroscopic discrimination of the two structurally similar polyunsaturated C 20 fatty acids (PUFAs) 5,8,11,14,17-eicosapentaenoic acid and 5,8,11,14-eicosatetraenoic acid (arachidonic acid) is shown. For this purpose their vibrational structures are studied by means of attenuated total reflection (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The fingerprint regions of the recorded spectra are found to be almost identical, while the C-H stretching mode regions around 3000 cm -1 show such significant differences as results of electronic and molecular structure alterations based on the different degree of saturation that both fatty acids can be clearly distinguished from each other.

  10. Decomposition of NO studied by infrared emission and CO laser absorption

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Flower, W. L.; Kruger, C. H.

    1975-01-01

    A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation has been developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. The rate constant for the dominant reaction of O and NO to yield N and O2 was inferred from comparisons with computer simulations of the reactive flow.

  11. Decomposition of NO studied by infrared emission and CO laser absorption

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Flower, W. L.; Monat, J. P.; Kruger, C. H.

    1974-01-01

    A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation was developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. Rate constants for dominant reactions were inferred from comparisons with computer simulations of the reactive flow.

  12. Thermal Physical, and Infrared Spectroscopic Studies on Glasses Prepared by Microwave Route

    SciTech Connect

    Jagadeesha, N.; Gowda, V. C. Veeranna; Chakradhar, R. P. S.; Reddy, C. Narayana

    2011-07-15

    This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO{sub 4/2}]{sup -} and [B{sub 2}V{sub 2}O{sub 9}]{sup 2-}) groups are confirmed by Infrared Spectroscopy of investigated glasses.

  13. Correlation Study Of Diffenrential Skin Temperatures (DST) For Ovulation Detection Using Infra-Red Thermography

    NASA Astrophysics Data System (ADS)

    Rao, K. H. S.; Shah, A. v.; Ruedi, B.

    1982-11-01

    The importance of ovulation time detection in the Practice of Natural Birth Control (NBC) as a contraceptive tool, and for natural/artificial insemination among women having the problem of in-fertility, is well known. The simple Basal Body Temperature (BBT) method of ovulation detection is so far unreliable. A newly proposed Differential Skin Temperature (DST) method may help minimize disturbing physiological effects and improve reliability. This paper explains preliminary results of a detailed correlative study on the DST method, using Infra-Red Thermography (IRT) imaging, and computer analysis techniques. Results obtained with five healthy, normally menstruating women volunteers will be given.

  14. Atomic Force Microscopy and Infrared Spectroscopy Studies of Hydrogen Baked Si Surfaces

    NASA Astrophysics Data System (ADS)

    Vatel, Olivier; Verhaverbeke, Steven; Bender, Hugo; Caymax, Matty; Chollet, Frederic; Vermeire, Bert; Mertens, Paul; André, Elie; Heyns, Marc

    1993-10-01

    A H2 pre-bake at temperatures over 1050°C is typically used prior to Si epitaxial growth. In this study surface microroughness probed with tapping mode Atomic Force Microscopy (AFM) is correlated with multiple internal reflection infrared spectroscopy measurements for the different steps involved before epitaxy. A novel sample preparation technique was used for the multiple internal reflection set-up. A strong correlation was found between the presence of surface terraces and the IR double monohydride peaks for H2 annealed Si surfaces. We therefore put forward that the terraces are due to the H2 pre-bake step. These terraces remain after epitaxial deposition.

  15. Study of advanced InSb arrays for SIRTF (Space Infrared Telescope Facility)

    NASA Technical Reports Server (NTRS)

    Hoffman, Alan; Feitt, Robert

    1989-01-01

    The Santa Barbara Research Center has completed a study leading to the development of advanced Indium Antimonide detector arrays for the Space Infrared Telescope Facility (SIRTF) Focal Plane Array Detector (FPAD) Subsystem of the Infrared Array Camera (IRAC) Band 1. The overall goal of the study was to perform design tradeoff studies, analysis and research to develop a Direct Readout Integrated Circuit to be hybridized to an advanced, high performance InSb detector array that would satisfy the technical requirements for Band 1 as specified in the IRAC Instrument Requirements Document (IRD), IRAC-202. The overall goal of the study was divided into both a near-term goal and a far-term goal. The near-term goal identifies current technology available that approaches, and in some cases meets the program technological goals as specified in IRAC-202. The far-term goal identifies technology development required to completely achieve SIRTF program goals. Analyses of potential detector materials indicates that InSb presently meets all Band 1 requirements and is considered to be the baseline approach due to technical maturity. The major issue with regard to photovoltaic detectors such as InSb and HgCdTe is to achieve a reduction in detector capacitance.

  16. Studies of fullerene absorption and production using an infrared free-electron laser

    SciTech Connect

    Affatigato, M.; Haglund, R.F.; Ying, Z.C.; Compton, R.N.

    1995-12-31

    Tunable photon sources such as free-electron lasers are potentially valuable tools in spectroscopic studies of fullerenes, a new class of carbon materials with unique cage structures. We have used the infrared free-electron-laser facility at Vanderbilt University to study the infrared absorption of gas-phase fullerene molecules and also to investigate the effects of an infrared laser in the synthesis and crystallization of fullerene materials. In one experiment, fullerene vapor was created in a heat pipe through which the FEL beam was passed; the transmission of the FEL beam relative to a reference detector was measured as a function of wavelength. A large (>10%) absorption of the IR laser was observed when it passed through C{sub 60} vapor at {approximately}800{degrees}C. Due to the broad spectral width of the FEL as well as spectral congestion, no spectral peaks were seen when the laser wavelength was tuned across a T{sub 1u}C{sub 60} IR mode near 7.0 {mu}. However, it is expected that the vibrational features can be resolved experimentally by passing the transmitted beam through a monochromator. In a separate experiment, the FEL beam was focused onto a surface of graphite or graphite/metal mixture target. Various fullerene molecules, including endohedral types, were produced when the soot was recovered from the ablation chamber. The yield of the products was measured to be {approximately}0.4 g/J of the incident laser energy. However, both the yield and the product distribution are virtually, the same as those in experiments using a nanosecond Nd:YAG laser. This suggests that the laser wavelength is not a crucial parameter in making fullerenes by laser ablation. Even when the laser is at resonance with one of the vibrational modes of C{sub 60}, the fullerene production is neither substantially enhanced nor suppressed.

  17. Luminescence studies and infrared emission of erbium-doped calcium zirconate phosphor.

    PubMed

    Tiwari, Neha; Dubey, Vikas

    2016-05-01

    The near-infrared-to-visible upconversion luminescence behaviour of Er(3+)-doped CaZrO3 phosphor is discussed in this manuscript. The phosphor was prepared by a combustion synthesis technique that is suitable for less-time-taking techniques for nanophosphors. The starting materials used for sample preparation were Ca(NO3)2.4H2O, Zr(NO3)4 and Er(NO3)2, and urea was used as a fuel. The prepared sample was characterized by X-ray diffraction (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopy. All prepared phosphors with variable Er(3+) concentrations (0.5-2.5 mol%) were studied by photoluminescence analysis. It was found that the excitation spectra of the prepared phosphor showed a sharp excitation peak centred at 980 nm. The emission spectra with variable Er(3+) concentrations showed strong peaks in the 555 nm and 567 nm range, with a dominant peak at 555 nm due to the ((2)H(11/2),(4)S(3/2)) transition and a weaker transition at 567 nm associated with 527 nm. Spectrophotometric determination of the peak was evaluated by the Commission Internationale de I'Eclairage (CIE) method These upconverted emissions were attributed to a two-photon process. The excitation wavelength dependence of the upconverted luminescence, together with its time evolution after infrared pulsed excitation, suggested that energy transfer upconversion processes were responsible for the upconversion luminescence. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer processes were discussed as possible upconversion mechanisms. The cross-relaxation process in Er(3+) was also investigated.

  18. Combined studies of chemical composition of urine sediments and kidney stones by means of infrared microspectroscopy.

    PubMed

    Tamošaitytė, Sandra; Hendrixson, Vaiva; Želvys, Arūnas; Tyla, Ramūnas; Kučinskienė, Zita A; Jankevičius, Feliksas; Pučetaitė, Milda; Jablonskienė, Valerija; Šablinskas, Valdas

    2013-02-01

    Results of the structural analysis of urinary sediments by means of infrared spectral microscopy are presented. The results are in good agreement with the results of standard optical microscopy in the case of single-component and crystalline urinary sediments. It is found that for noncrystalline or multicomponent sediments, the suggested spectroscopic method is superior to optical microscopy. The chemical structure of sediments of any molecular origin can be elucidated by this spectroscopic method. The method is sensitive enough to identify solid particles of drugs present in urine. Sulfamethoxazole and traces of other medicines are revealed in this study among the other sediments. We also show that a rather good correlation exists between the type of urinary sediments and the renal stones removed from the same patient. Spectroscopic studies of urinary stones and corresponding sediments from 76 patients suffering from renal stone disease reveal that in 73% of cases such correlation exists. This finding is a strong argument for the use of infrared spectral microscopy to prevent kidney stone disease because stones can be found in an early stage of formation by using the nonintrusive spectroscopic investigation of urinary sediments. Some medical recommendations concerning the overdosing of certain pharmaceuticals can also be derived from the spectroscopic studies of urinary sediments.

  19. a Fourier Transform Infrared Study of Competing Equilibrium in P-Vinyl Phenol) Blends.

    NASA Astrophysics Data System (ADS)

    Lichkus, Andrew Murray

    In this thesis a Fourier transform infrared (FTIR) spectroscopic study of polymer blends containing poly(p -vinyl phenol) (PVPh) is presented. The characteristics of the intermolecular hydrogen bonding arising from the interaction between the phenolic hydroxyl and carbonyl groups of the different polyacrylates are discussed. The experimental work is focussed primarily on the PVPh with polyacrylate blend systems which include poly(methyl acrylate), poly(ethyl acrylate), poly(n-butyl acrylate), poly(n-pentyl acrylate) and poly(2-ethyl-hexyl acrylate). The infrared bands associated with the intermolecular hydrogen bonding between the phenolic hydroxyl and acrylate carbonyl group are identified. The proportion of hydrogen bonded carbonyl groups in these blends is quantified both as a function of composition and temperature. The effect of the pendant group on the extent of the intermolecular interaction is discussed. The experimental results from this study, including those obtained by other workers, are recast into theoretical phase diagrams via the application of an association model describing binary blends involving hydrogen bonds. The phase diagrams are compared with experimental observations and found to be in broad general agreement. The theoretical predictions of the model with respect to the effect of molecular weight and polymer repeat unit size on the predicted phase behavior is discussed. This study confirms that the phase behavior of polymer blends exhibiting hydrogen bonding can be adequately described by a model employing a competing equilibrium scheme which includes an excess free energy function to account for the specific interactions.

  20. Study on dietary fibre by Fourier transform-infrared spectroscopy and chemometric methods.

    PubMed

    Chylińska, Monika; Szymańska-Chargot, Monika; Kruk, Beata; Zdunek, Artur

    2016-04-01

    Fresh fruit is an important part of the diet of people all over the world as a significant source of water, vitamins and natural sugars. Nowadays it is also one of the main sources of dietary fibre. In fruit the dietary fibre is simply cell wall consisting essentially of polysaccharides. The aim of present study was to predict the contents of pectins, cellulose and hemicelluloses by partial least squares regression (PLS) analysis on the basis of Fourier transform-infrared (FT-IR) spectra of fruit cell wall residue. The second purpose was to analyse the composition of dietary fibre from fruit based on FT-IR spectral information in combination with chemometric methods (principle components analysis (PCA) and hierarchical cluster analysis (HCA)). Additionally the contents of polysaccharides in studied fruits were determined by analytical methods. It has been shown that the analysis of infrared spectra and the use of multivariate statistical methods can be useful for studying the composition of dietary fibre. PMID:26593472

  1. Effects of Somatothermal Far-Infrared Ray on Primary Dysmenorrhea: A Pilot Study

    PubMed Central

    Ke, Yu-Min; Ou, Ming-Chiu; Ho, Cheng-Kun; Lin, Yung-Sheng; Liu, Ho-Yen; Chang, Wen-An

    2012-01-01

    The purpose of this study was to assess the beneficial effects of using a far-infrared (FIR) belt on the management of patients with primary dysmenorrhea. This is the first study to determine the efficacy of somatothermal FIR using a parallel-arm randomized sham-controlled and double-blinded design with objective physical evidence and psychometric self-reports. Fifty-one Taiwanese women with primary dysmenorrhea were enrolled in the study. Results indicate that there was an increased abdominal temperature of 0.6°C and a 3.27% increase in abdominal blood flow in the FIR group (wearing FIR belt) compared to those in the control group (wearing sham belt). Verbal rating scale and numeric rating scale scores in the FIR group were both lower than those in the control group. Compared to the blank group (wearing no belt), the average dysmenorrhea pain duration of the FIR group was significantly reduced from 2.5 to 1.8 days, but there was no significant difference in the control group. These results demonstrate that the use of a belt made of far-infrared ceramic materials can reduce primary dysmenorrhea. PMID:23320024

  2. Combined studies of chemical composition of urine sediments and kidney stones by means of infrared microspectroscopy

    NASA Astrophysics Data System (ADS)

    Tamošaitytė, Sandra; Hendrixson, Vaiva; Želvys, Arūnas; Tyla, Ramūnas; Kučinskienė, Zita A.; Jankevičius, Feliksas; Pučetaitė, Milda; Jablonskienė, Valerija; Šablinskas, Valdas

    2013-02-01

    Results of the structural analysis of urinary sediments by means of infrared spectral microscopy are presented. The results are in good agreement with the results of standard optical microscopy in the case of single-component and crystalline urinary sediments. It is found that for noncrystalline or multicomponent sediments, the suggested spectroscopic method is superior to optical microscopy. The chemical structure of sediments of any molecular origin can be elucidated by this spectroscopic method. The method is sensitive enough to identify solid particles of drugs present in urine. Sulfamethoxazole and traces of other medicines are revealed in this study among the other sediments. We also show that a rather good correlation exists between the type of urinary sediments and the renal stones removed from the same patient. Spectroscopic studies of urinary stones and corresponding sediments from 76 patients suffering from renal stone disease reveal that in 73% of cases such correlation exists. This finding is a strong argument for the use of infrared spectral microscopy to prevent kidney stone disease because stones can be found in an early stage of formation by using the nonintrusive spectroscopic investigation of urinary sediments. Some medical recommendations concerning the overdosing of certain pharmaceuticals can also be derived from the spectroscopic studies of urinary sediments.

  3. Development and applications of infrared structural biology

    NASA Astrophysics Data System (ADS)

    Kang, Zhouyang

    Aspartic acid (Asp), Glutamic acid (Glu) and Tyrosine (Tyr) often play critical roles at the active sites of proteins. Probing the structural dynamics of functionally important Asp/Glu and Tyr provides crucial information for protein functionality. Time-resolved infrared structural biology offers strong advantages for its high structural sensitivity and broad dynamic range (picosecond to kilosecond). In order to connect the vibrational frequencies to specific structures of COO- groups and phenolic --OH groups, such as the number, type, and geometry of hydrogen bond interactions, we develop two sets of vibrational structural markers (VSM), built on the symmetric and asymmetric stretching frequencies for COO- and C-O stretching and C-O-H bending frequencies for phenolic --OH. Extensive quantum physics (density functional theory) based computational studies, combined with site-specific isotope labeling as well as site-directed mutagenesis, and experimental FTIR data on Asp/Glu in proteins, are used to establish a unique correlation between the vibrations and multiple types of hydrogen bonding interactions. Development of those vibrational structural markers significantly enhances the power of time-resolved infrared structural biology for the study of functionally important structural dynamics of COO- from Asp/Glu and phenolic --OH from Tyr residues in proteins, including rhodopsin for biological signaling, bacteriorhodopsin and PYP for proton transfer, photosystem II for energy transformation, and HIV protease for enzymatic catalysis. Furthermore, this approach can be adopted in the future development of vibrational structural markers for other functionally important amino acid residues in proteins, such as arginine (Arg), histidine (His), and serine (Ser).

  4. Mechanical Properties of Nuclear Fuel Surrogates using Picosecond Laser Ultrasonics

    SciTech Connect

    David Hurley; Marat Khafizov; Farhad Farzbod; Eric Burgett

    2013-05-01

    Detailed understanding between microstructure evolution and mechanical properties is important for designing new high burnup nuclear fuels. In this presentation we discuss the use of picosecond ultrasonics to measure localize changes in mechanical properties of fuel surrogates. We develop measurement techniques that can be applied to investigate heterogeneous elastic properties caused by localize changes in chemistry, grain microstructure caused by recrystallization, and mechanical properties of small samples prepared using focused ion beam sample preparation. Emphasis is placed on understanding the relationship between microstructure and mechanical properties

  5. Picosecond dynamics of photoexcited carriers in interacting silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Kořínek, Miroslav; Trojánek, František; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Kübel, Christian; Malý, Petr

    2016-07-01

    The non-radiative Auger carrier recombination plays an important role in physics and the application of semiconductor nanocrystals. Here we report on the effect of inter-nanocrystal carrier interaction on Auger recombination. We prepared a special set of samples containing silicon nanocrystals embedded in silicon oxide with well-defined geometry. The picosecond carrier recombination rate measured by femtosecond pump and probe technique was found to be strongly dependent on the inter-nanocrystal separation. The observed decrease of the decay rate with nanocrystal separation on the nanometer scale is interpreted in terms of the wave function overlap appearing in the relevant matrix element describing the recombination process.

  6. In Vitro picosecond ultrasonics in a single cell

    NASA Astrophysics Data System (ADS)

    Rossignol, C.; Chigarev, N.; Ducousso, M.; Audoin, B.; Forget, G.; Guillemot, F.; Durrieu, M. C.

    2008-09-01

    Ultrasonics signals at frequencies 5.7±0.1 and 6.8±0.1GHz are measured in two organelles of a single vegetal cell in vitro with a picosecond ultrasonic technique. Using standard values for cell optical index, ultrasound velocities of 1.6±0.1 and 2.0±0.1μm/ns are measured from several signals recorded in the vacuole and in the nucleus of a single Allium cepa cell, respectively. A 1μm lateral and 0.25μm depth resolution is attained.

  7. Cryogenically-cooled Yb:YGAG ceramic picosecond oscillator

    NASA Astrophysics Data System (ADS)

    Mužik, J.; Jelínek, M.; Miura, T.; Smrž, M.; Endo, A.; Mocek, T.; Kubeček, V.

    2016-04-01

    In this work, a passively mode-locked Yb:YGAG (Yb:Y3Ga2Al3O12) ceramic laser generating picosecond pulses at liquid-nitrogen temperature is demonstrated. The Yb:YGAG has a similar structure to Yb:YAG, but its emission bandwidth at cryogenic temperature remains much broader, which is advantageous for ultrashort pulse generation and amplification. Using this laser material, a stable train of pulses at a wavelength of 1026 nm was obtained, with measured pulse duration of 2.4 ps, which is more than four times shorter than that achieved with a cryogenically-cooled Yb:YAG.

  8. A rapid-scanning autocorrelation scheme for continuous monitoring of picosecond laser pulses

    SciTech Connect

    Yasa, Zafer A.; Amer, Nabil M.

    1981-03-01

    In this paper, we describe a scheme for rapidly introducing a periodic linear time delay to a train of picosecond laser pulses. Finally, by incorporating this scheme in one arm of the Michelson interferometer of a conventional autocorrelator, the second order intensity autocorrelation function of a cw train of picosecond pulses is continuously displayed on an oscilloscope.

  9. Infrared studies of induced superconductivity in indium-arsenide quantum wells

    NASA Astrophysics Data System (ADS)

    Eckhause, Tobias Andrew

    The describe experiments which probe the electrical and infrared optical properties of superconductor-semiconductor hybrid structures, specifically structures where superconducting Nb contacts the two-dimensional electron gas in an InAs quantum well. In order to study the supercurrent-carrying Andreev states in a Josephson junction, we conduct transport, experiments in Josephson field-effect transistors, where a voltage applied to an insulated gate modulates the density of electrons in and the supercurrent through an InAs-based weak link. The density-dependence of the critical current fits a model for the Andreev states in the junction in which quasiparticles travel ballistically across the quantum well between superconducting electrodes. Probing the dynamics of these states on the scale of the superconducting energy gap in Nb, we find robust signatures of the proximity effect in the InAs using far-infrared transmission spectroscopy. A model for the conductivity of superconducting thin films predicts transmission spectra which show similarities to the transmission spectra measured in our structures. From this fit we extract an effective energy gap in the InAs quantum well due to the proximity of superconducting Nb. We probe these structures in both superconductor/normal metal geometries---where the superconducting Nb lies directly on top of a layer of InAs---and superconductor/normal metal/superconductor geometries---where the an InAs quantum well connects superconducting Nb stripes. In both geometries we observe proximity effects in the far-infrared transmission spectra of the InAs.

  10. [Study on XRD and infrared spectroscopy of nephrites from Xinjiang and Xiuyan, Liaoning].

    PubMed

    Chen, Quan-Li; Bao, De-Qing; Yin, Zuo-Wei

    2013-11-01

    The nephrite species with different colors from Xinjiang and Xiuyan, Liaoning, including gray nephrite, yellow nephrite, white nephrite, jasper and He-Mo nephrite, a special nephrite from Xiuyan, were selected for the present study. The gemological testing method, infrared absorption spectroscopy and X-ray powder diffraction were used to analyze and compare the gemological characteristics of the nephrite with different colors and textures from the above localities, in order to understand the similarities and differences between these nephrites with similar colors but different origin, and provide a theoretical basis for the identification of the nephrite origin. The results show that the nephrites from Xinjiang and Xiuyan, Liaoning province have similar gemological properties. They have similar refractive index of 1.60-1.62 and density of 2.660-3.020 g x cm(-3), and only the density has some differences with different colors. The fluorescence.characteristics are not obvious in these nephrites. The major constituent minerals for these nephrites are tremolite, and small amounts of clay minerals such as chlorite and illite are found in the jasper from Xinjiang. Based on the X-ray powder diffraction analysis on the different types of nephrite from two localities, it was shown that the character of spectra peaks and diffraction intensity of different types of nephrite can reflect the texture of the nephrite and the size of crystalline particles to some extent. The infrared absorption spectra are similar for the nephrites from two localities. The infrared absorption spectrum does not make sense to identify the origin and species of nephrites.

  11. In Situ Fourier transform infrared spectroscopic study of the thermal degradation of isotactic poly(propylene).

    PubMed

    He, Peng; Xiao, Yan; Zhang, Puming; Zhu, Na; Zhu, Xinyuan; Yan, Deyue

    2005-01-01

    The conformational change of isotactic poly(propylene) (iPP) during the thermal degradation process has been carefully studied by in situ Fourier transform infrared (FT-IR) spectroscopy. This new method of studying thermal degradation of iPP not only shows the conventional kinetic parameter information of thermal degradation such as the degradation activation energy DeltaE and the degradation factor n, which are in accord with the results of traditional thermogravimetry experiments, but also indicates that many significant molecular structure changes occur during the thermal degradation process that come from some characteristic absorption band changes of in situ FT-IR. A multivariate approach, principal components analysis (PCA), is applied to the analysis of infrared (IR) data, and the results further confirm the multi-step processes of the thermal degradation of iPP. Above all, this is a new application to polymer thermal degradation by in situ FT-IR that connects the intermediate conformational change with final results during thermal degradation.

  12. STUDIES OF THE Be STAR X PERSEI DURING A BRIGHT INFRARED PHASE

    SciTech Connect

    Mathew, Blesson; Banerjee, D. P. K.; Naik, Sachindra; Ashok, N. M.

    2013-06-15

    We present multi-epoch photometric and spectroscopic near-infrared observations of the Be star X Persei in the JHK bands covering the wavelength range 1.08-2.35 {mu}m. Combining results from our earlier studies with the present observations, it is shown that the equivalent widths and line fluxes of the prominent H I and He I lines anti-correlate with the strength of the adjacent continuum. That is, during the span of the observations, the JHK broadband fluxes increase while the emission equivalent width values of the H I and He I lines decrease (the lines under consideration being the Paschen and Brackett lines of hydrogen and the 1.7002 {mu}m and 2.058 {mu}m lines of helium). Such an anti-correlation effect is not commonly observed in Be stars in the optical; in the infrared, this may possibly be the first reported case of such behavior. We examine different mechanisms that could possibly cause it and suggest that it could originate due to a radiatively warped, precessing circumstellar disk. It is also shown that during the course of our studies, X Per evolved to an unprecedented state of high near-IR brightness with J, H, K magnitudes of 5.20, 5.05, and 4.84, respectively.

  13. High-resolution infrared studies of perdeutero-spiropentane, C5D8

    NASA Astrophysics Data System (ADS)

    Erickson, B. A.; Ju, X.; Nibler, J. W.; Beaudry, C. M.; Blake, T. A.

    2016-07-01

    Perdeutero-spiropentane (C5D8) has been synthesized, and infrared and Raman spectra are reported for the first time. Wavenumber assignments are made for most of the fundamental vibrational states. Gas phase infrared spectra were recorded at a resolution (0.002 cm-1) sufficient to resolve individual rovibrational lines and show evidence of strong Coriolis and/or Fermi resonance interactions for most bands. However a detailed rovibrational analysis of the fundamental ν15 (b2) parallel band proved possible, and a fit of more than 1600 lines yielded a band origin of 1053.84465(10) cm-1 and ground state constants (in units of cm-1): B0 = 0.1120700(9), DJ = 1.51(3) × 10-8, DJK = 3.42(15) × 10-8. We note that the B0 value is significantly less than a value of Ba = 0.1140 cm-1 calculated using structural parameters from an earlier electron diffraction (ED) study, whereas one expects Ba to be lower than B0 because of thermal averaging over higher vibrational levels. A similar discrepancy was noted in an earlier study of C5H8 (Price et al., 2011). The structural and spectroscopic results are in good accord with values computed at the anharmonic level using the B3LYP density functional method with a cc-pVTZ basis set.

  14. Optical and electrical studies of single walled carbon nanotubes for infrared sensing and photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Omari, Mones A.

    Carbon nanotubes are emerging as highly promising opto-electro-mechanical device components essential for the development of a variety of hybrid opto-electronic, electro-mechanical and bio-medical technologies on the nanoscale and have been a subject of continued research. In particular, single-walled carbon nanotubes are predicted to exhibit strong light absorption induced by photon-assisted electronic transitions, free carrier and plasmonic-based absorption. Single-walled carbon nanotubes have been confirmed to exhibit a strong photoconduction response in the infrared range, which can provide many new opportunities in engineering nano-photovoltaic and optoelectronic devices. At the same time, the use of strong chemical reagents has been long considered as one of the key processing steps for the separation and purification of single-walled carbon nanotube post-synthesis. In this work, optically-induced voltage in carbon nanotube bundles and thin-films configured as two-terminal resistive elements and operating as junctionless photo-cells in the infrared range as well as the time-dependent wet-processing of HiPCo nanotubes in phosphoric acid and its effect on the structural, transport, infrared light absorption, and photoconduction characteristics were studied. As the photo-voltage generated is found to appear only for asymmetric and off-contact illuminations, the effect is explained based on a photo-generated heat flow model. The engineered cell prototypes were found to yield electrical powers of ˜ 30 pW while demonstrating improved conversion efficiency under high-flux illumination. The cell is also shown to act as an uncooled infrared sensor, with its dark-to-photocurrent ratio improving as temperature increases. The wet-processing of HiPCo nanotubes was done for a nominal time intervals of 1, 2 and 3 hours. The treatment was found to be a two-step process that initially results in the removal and partial replacement of most pre-existing C-O, O-H and CHx groups

  15. [The Study on Infrared Spectra of 7-Hydroxycoumarin by Density Functional Theory].

    PubMed

    Jia, Fei-yun; Su, Yu; Ran, Ming; Zhu, Jiang; Zhang, Bo

    2016-01-01

    Infrared spectroscopy is an important source of information for the identification of the compounds structure and it is great significant for biological activity research of natural and organic drug molecules. With the theoretical calculation method is more reasonable and calculation accuracy continues to improve, Theoretical calculate advantage is more obvious in the infrared spectrum simulation and vibration modes attributable identified. And it has important reference value for experimental study of infrared spectral analysis. Using density functional theory, geometry optimizations and frequencies calculation of 7-Hydroxycoumarin were performed at the level of B3LYP/6-311G(d, p), the stable structure and all vibration modes of 7-Hydroxycoumarin were attained. The results show that the infrared absorption peak of 7-hydroxycoumarin is mainly distributed in the several regions in wave number of 3 700-3 500, 3 150-3 000, 1 750-1 400, 1 400-1 000, 1 000-50 cm(-1). In addition to the vibration in a wave number range of 3 700-3 500, 3 150-3 000 cm(-1) is relatively independent, and were attributed to OH stretching vibration and benzene ring CH stretching vibration, the other several vibration regions are more complex, the different degree of spectral peaks is composed of multiple vibration modes. Finally, based on the theoretical analysis of the vibration mode, the vibration modes of 7-Hydroxycoumarin molecule were assigned, and in order to discuss the reliability of theoretical calculation method, the correlation diagram of the main absorption peak of 7-hydroxyl group was drawn from the theoretical value of X axis and the experimental value of Y axis, the correlation between experimental IR data and calculated IR data of 7-Hydroxycoumarin was analyzed through the linear regression method. Results show that they have good correlation, correlation coefficient values "r" equals 0.998 5, and the theory calculation of 7-Hydroxycoumarin IR by density functional theory at

  16. Quantitative infrared spectroscopic method for the study of the hydration of ions in aqueous solutions

    SciTech Connect

    Kristiansson, O.; Lindgren, J.; de Villepin, J.

    1988-05-05

    An infrared spectroscopic method for the study of the hydration of ions in aqueous solutions has been developed. OD stretching bands of isotopically dilute HDO molecules in the first hydration sphere of ions are obtained when the absorption from H/sub 2/O molecules and HDO molecules in the bulk water are removed by a double difference technique. The method is applied to aqueous solutions of Ni(ClO/sub 4/)/sub 2/, Ni(BF/sub 4/)/sub 2/, and Ni(PF/sub 6/)/sub 2/. Coordination numbers of 4.6 +/- 0.8 for the ClO/sub 4//sup -/ anion and 3.9 +/- 0.8 for the BF/sub 4//sup -/ anion are obtained. A systematic study of the influence of different salt and HDO concentrations has been undertaken. It is found that Lambert-Beer's law is valid in the concentration ranges studied.

  17. A bipolar radiofrequency, infrared, vacuum and mechanical massage device for treatment of cellulite: a pilot study.

    PubMed

    Hexsel, Doris M; Siega, Carolina; Schilling-Souza, Juliana; Porto, Manoela D; Rodrigues, Ticiana C

    2011-12-01

    Cellulite has a complex and multifactorial etiology. Synergistic action on treating cellulite has gained support in the treatment of cellulite. This study evaluated safety and efficacy of a bipolar radiofrequency, infrared, vacuum and mechanical massage device for cellulite treatment and reduction of body measures. This was a pilot study, which assessed 9 subjects who presented body mass index from 18 to 25 Kg/Kg and at least grade 6 in the Cellulite Severity Scale (CSS). All subjects underwent a 12-session treatment of posterior thighs and buttocks. There was a significant reduction of the hip circumference (p = 0.001), however, no changes in thigh circumferences were observed (p = 0.4). CSS has improved specifically on both buttocks [p = 0.002 (left side) and p = 0.038 (right side)], and no changes were observed on thighs. The studied device demonstrated efficacy in the reduction of cellulite severity and body circumference measures in the buttocks.

  18. [Infrared spectroscopic study on storage substance mobilization of crop seeds in germination].

    PubMed

    Liu, Gang; Tan, Li-Ping; Dong, Qin

    2008-01-01

    The traditional method to study the storage substance mobilization of seeds during the process of germination is chemical extraction, which is troublesome and time consuming. In the present paper, Fourier transform infrared spectroscopy was used to study the storage substance mobilization of legume and cereal seeds in germination. The spectral results show that legume seeds (soybean, pea and broad bean) exhibit similar remarkable changes in the region from 1 000 to 1 200 cm(-1) in germination, which suggest that the storage carbohydrates in endosperm of legume seeds are mobilized during the process of germination. Notable changes were observed on amide bands of protein and lipid band in the spectra of germinating cereal seeds (rice, wheat and barley), indicating that storage proteins and lipids in cotyledon were utilized during the process of cereal seed germination. The results suggest that vibrational spectroscopy has the advantages of rapidress and convenience in the study of crop seeds and seed physiology.

  19. Femtosecond wavelength-tunable OPCPA system based on picosecond fiber laser seed and picosecond DPSS laser pump.

    PubMed

    Danilevičius, R; Zaukevičius, A; Budriūnas, R; Michailovas, A; Rusteika, N

    2016-07-25

    We present a compact and stable femtosecond wavelength-tunable optical parametric chirped pulse amplification (OPCPA) system. A novel OPCPA front-end was constructed using a multi-channel picosecond all-in-fiber source for seeding DPSS pump laser and white light supercontinuum generation. Broadband chirped pulses were parametrically amplified up to 1 mJ energy and compressed to less than 40 fs duration. Pulse wavelength tunability in the range from 680 nm to 930 nm was experimentally demonstrated. PMID:27464199

  20. Time-resolved infrared absorption studies of the dynamics of radical reactions.

    SciTech Connect

    Macdonald, R. G.

    2008-01-01

    There is very little information available about the dynamics of radical+radical interactions. These processes are important in combustion being chain termination steps as well as generating new molecular species. To study these processes, a new experimental apparatus has been constructed to investigate radical-radical dynamics. The first radical or atomic species is produced with a known concentration in a microwave discharge flow system. The second is produced by pulsed laser photolysis of a suitable photolyte. The time dependence of individual rovibrational states of the product is followed by absorption of a continuous infrared laser. This approach will allow the reaction of interest to be differentiated from other radical reactions occurring simultaneously. The experimental approach is highly versatile, being able to detect a number of molecular species of particular interest to combustion processes such as water, methane, acetylene etc. at the state specific level. State specific infrared absorption coefficients of radicals can be measured in situ allowing for the determination of the absolute concentrations and hence branching ratios for reactions having multiple reaction pathways.

  1. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  2. A Study of Planetary Nebulae using the Faint Object Infrared Camera for the SOFIA Telescope

    NASA Technical Reports Server (NTRS)

    Davis, Jessica

    2012-01-01

    A planetary nebula is formed following an intermediate-mass (1-8 solar M) star's evolution off of the main sequence; it undergoes a phase of mass loss whereby the stellar envelope is ejected and the core is converted into a white dwarf. Planetary nebulae often display complex morphologies such as waists or torii, rings, collimated jet-like outflows, and bipolar symmetry, but exactly how these features form is unclear. To study how the distribution of dust in the interstellar medium affects their morphology, we utilize the Faint Object InfraRed CAmera for the SOFIA Telescope (FORCAST) to obtain well-resolved images of four planetary nebulae--NGC 7027, NGC 6543, M2-9, and the Frosty Leo Nebula--at wavelengths where they radiate most of their energy. We retrieve mid infrared images at wavelengths ranging from 6.3 to 37.1 micron for each of our targets. IDL (Interactive Data Language) is used to perform basic analysis. We select M2-9 to investigate further; analyzing cross sections of the southern lobe reveals a slight limb brightening effect. Modeling the dust distribution within the lobes reveals that the thickness of the lobe walls is higher than anticipated, or rather than surrounding a vacuum surrounds a low density region of tenuous dust. Further analysis of this and other planetary nebulae is needed before drawing more specific conclusions.

  3. A multispectral study of an extratropical cyclone with Nimbus 3 medium resolution infrared radiometer data

    NASA Technical Reports Server (NTRS)

    Holub, R.; Shenk, W. E.

    1973-01-01

    Four registered channels (0.2 to 4, 6.5 to 7, 10 to 11, and 20 to 23 microns) of the Nimbus 3 Medium Resolution Infrared Radiometer (MRIR) were used to study 24-hr changes in the structure of an extratropical cyclone during a 6-day period in May 1969. Use of a stereographic-horizon map projection insured that the storm was mapped with a single perspective throughout the series and allowed the convenient preparation of 24-hr difference maps of the infrared radiation fields. Single-channel and multispectral analysis techniques were employed to establish the positions and vertical slopes of jetstreams, large cloud systems, and major features of middle and upper tropospheric circulation. Use of these techniques plus the difference maps and continuity of observation allowed the early detection of secondary cyclones developing within the circulation of the primary cyclone. An automated, multispectral cloud-type identification technique was developed, and comparisons that were made with conventional ship reports and with high-resolution visual data from the image dissector camera system showed good agreement.

  4. An experimental study on infrared drying kinetics of an aqueous adhesive supported by polymer composite

    NASA Astrophysics Data System (ADS)

    Allanic, Nadine; Le Bideau, Pascal; Glouannec, Patrick; Deterre, Rémi

    2016-04-01

    The infrared drying of an aqueous polymer emulsion spread on a thin composite flat film is experimentally studied. The composite film is composed of polyamide fibers supported by a poly(vinyl fluoride) film. The aqueous polymer is an Ethylene Vinyl Acetate emulsion playing the role of adhesive. It is spread over the film with a low thickness, about one hundred micrometers. The aim of this work is to understand the effects of the presence of fibers on the drying of this thin-layer product. With this in mind, a specific laboratory set up composed of a near infrared heater is used in order to get the drying kinetics. First, incident heat fluxes received at the product surface and transmittances of materials (semi-transparent medium) are measured with an ad-hoc heat flux sensor. Then, many experiments are performed with and without fibers. For linking the final moisture content to the fibers thermal and hydric behavior, a microscopic analysis of the dried samples is investigated. This analysis is performed for two thicknesses of polymer corresponding to two covering rates of fibers.

  5. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers.

    PubMed

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C; Belkin, Mikhail A

    2016-02-16

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1-6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides.

  6. Studying the Diurnal Cycle of Convection Using a TRMM-Calibrated Infrared Rain Algorithm

    NASA Technical Reports Server (NTRS)

    Negri, Andrew J.

    2005-01-01

    The development of a satellite infrared (IR) technique for estimating convective and stratiform rainfall and its application in studying the diurnal variability of rainfall on a global scale is presented. The Convective-Stratiform Technique (CST), calibrated by coincident, physically retrieved rain rates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), is applied over the global tropics. The technique makes use of the IR data from the TRMM Visible/Infrared Scanner (VIRS) before application to global geosynchronous satellite data. The calibrated CST technique has the advantages of high spatial resolution (4 km), filtering of nonraining cirrus clouds, and the stratification of the rainfall into its convective and stratiform components, the last being important for the calculation of vertical profiles of latent heating. The diurnal cycle of rainfall, as well as the division between convective and Stratiform rainfall will be presented. The technique is validated using available data sets and compared to other global rainfall products such as Global Precipitation Climatology Project (GPCP) IR product, calibrated with TRMM Microwave Imager (TMI) data. Results from five years of PR data will show the global-tropical partitioning of convective and stratiform rainfall.

  7. Studying the Diurnal Cycle of Convection Using a TRMM-Calibrated Infrared Rain Algorithm

    NASA Technical Reports Server (NTRS)

    Negri, Andrew J.; Adler, Robert F.; Huffman, George J.; Manyin, Michael

    2004-01-01

    The development of a satellite infrared (IR) technique for estimating convective and stratiform rainfall and its application in studying the diurnal variability of rainfall on a global scale is presented. The Convective-Stratiform Technique (CST), calibrated by coincident, physically retrieved rain rates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), is applied over the global tropics. The technique makes use of the IR data from the TRMM Visible/Infrared Scanner (VIRS) before application to global geosynchronous satellite data. The calibrated CST technique has the advantages of high spatial resolution (4 km), filtering of non-raining cirrus clouds, and the stratification of the rainfall into its convective and stratiform components, the last being important for the calculation of vertical profiles of latent heating. The diurnal cycle of rainfall, as well as the division between convective and stratiform rainfall will be presented. The technique is validated using available data sets and compared to other global rainfall products such as Global Precipitation Climatology Project (GPCP) IR product, calibrated with TRMM Microwave Imager (TMI) data. Results from five years of PR data will show the global-tropical partitioning of convective and stratiform rainfall.

  8. Fourier transform infrared spectroscopy studies of water-polymer interactions in chemically amplified photoresists

    SciTech Connect

    McDonough, Laurie A.; Chikan, Viktor; Kim, Zee Hwan; Leone, Stephen R.; Hinsberg, William D.

    2004-12-08

    Fourier-Transform Infrared (FTIR) absorption spectroscopy is implemented to measure the infrared spectrum of water absorbed by the Poly(t-butoxycarbonylstyrene) (tBOC) and the ketal-protected Poly(hydroxystyrene) (KRS-XE) polymer photoresists. The shape and intensity of the OH stretching band of the water spectrum is monitored in a variety of humidity conditions in order to obtain information on the hydrogen-bonding interactions between the water and the polymer chains. The band is deconvoluted into four sub-bands, which represent four types of water molecules in different environments. Because of the hydrophilicity of the polymers studied, a large portion of the sorbed water molecules is believed to be strongly bound to the polar sites of the polymer. The ratios of each type of water are found to be dependent on the humidity conditions to which the sample was exposed. At higher humidities, there is an increase in the fraction of free and weakly-bound water molecules. These findings are used to explain the humidity dependence of the deprotection reaction rates, since certain types of water may slow transport of reactive species within the polymer network.

  9. Application of Fourier transform infrared spectroscopy to studies of aqueous protein solutions.

    PubMed

    Zuber, G; Prestrelski, S J; Benedek, K

    1992-11-15

    Modern protein Fourier transform infrared (FT-IR) spectroscopy has proven to be a versatile and sensitive technique, applicable to many aspects of protein characterization. The major practical drawback for the FT-IR spectroscopy of proteins is the large absorbance band of water, which overlaps the amide I resonances. D2O is often substituted for H2O in infrared experiments. Removal of water from protein samples can be complicated and tedious and potentially lead to denaturation, aggregation, or sample loss. Solvent removal by dialysis is difficult for suspensions and sols. A new method called the D2O dilution technique (Ddt) is described which simplifies the sample preparation step and improves the solvent subtraction. The effect of the D2O concentration on the IR spectrum of aqueous solutions of several model proteins was studied. Dilution of aqueous samples with D2O yields good quality spectra. The Ddt has been evaluated for quantitative analysis using standard proteins and its applicability to solutions and suspensions of a genetically engineered malaria antigen is demonstrated. Use of resolution-enhancement techniques with spectra in mixed solvents has also been investigated. PMID:1489088

  10. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers

    PubMed Central

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C.; Belkin, Mikhail A.

    2016-01-01

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1–6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides. PMID:26879901

  11. Studies in Above- and Below-Threshold Harmonics in Argon with an Infrared Femtosecond Laser

    NASA Astrophysics Data System (ADS)

    Chew, Andrew; Yin, Yanchun; Li, Jie; Ren, Xiaoming; Cunningham, Eric; Wu, Yi; Chang, Zenghu

    2016-05-01

    We investigate and compare the above- and below-threshold harmonics in Argon gas using our recently-developed 1 kHz, two-cycle (11.4 fs), 3mJ, and carrier-envelope-phase(CEP)-stable laser at 1.6 μm. Such ultraviolet pulses can serve as pump or probe for studying dynamics in atoms and molecules. Unlike high harmonics with photon energy well above the ionization potential, the mechanism for generating harmonics near the ionization threshold is still under intense investigation. Previous work by Chini et al. on below-threshold harmonics was done using a 0.8 μm few-cycle Ti:Sapphire spectrally-broadened source with energy up to 300 μJ. It has been predicted by theory that free-free transitions dominate the below threshold harmonic generation as the laser wavelength increase from near infrared to mid-infrared. We are therefore interested in investigating how using a longer wavelength laser might lead to changes to the behavior of below-threshold harmonics when we vary various parameters. We report the π-periodity CEP dependence and ellipticity dependence of the above- and below-threshold harmonics. This material was based on work supported by National Science Foundation (1068604), Army Research Office (W911NF-14-1-0383), Air Force Office of Scientific Research (FA9550-15-1-0037) and the DARPA PULSE program by a Grant from AMRDEC (W31P4Q1310017).

  12. Mid-infrared study of stones from the Sutter's Mill meteorite

    NASA Astrophysics Data System (ADS)

    Nuevo, Michel; Sandford, Scott A.; Flynn, George J.; Wirick, Susan

    2014-11-01

    The Sutter's Mill meteorite fell in northern California on April 22, 2012. Several fragments of the meteorite were recovered, some of them shortly after the fall, others several days later after a heavy rainstorm. In this work, we analyzed several samples of four fragments―SM2, SM12, SM20, and SM30―from the Sutter's Mill meteorite with two infrared (IR) microscopes operating in the 4000-650 cm-1 (2.5-15.4 μm) range. Spectra show absorption features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics. Spectra of specific minerals vary from one particle to another within a given stone, and even within a single particle, indicating a nonuniform mineral composition. Infrared features associated with aliphatic CH2 and CH3 groups associated with organics are also seen in several spectra. However, the presence of organics in the samples studied is not clear because these features overlap with carbonate overtone bands. Finally, other samples collected within days after the rainstorm show evidence for bacterial terrestrial contamination, which indicates how quickly meteorites can be contaminated on such small scales.

  13. THE MILKY WAY PROJECT: A STATISTICAL STUDY OF MASSIVE STAR FORMATION ASSOCIATED WITH INFRARED BUBBLES

    SciTech Connect

    Kendrew, S.; Robitaille, T. P.; Simpson, R.; Lintott, C. J.; Bressert, E.; Povich, M. S.; Sherman, R.; Schawinski, K.; Wolf-Chase, G.

    2012-08-10

    The Milky Way Project citizen science initiative recently increased the number of known infrared bubbles in the inner Galactic plane by an order of magnitude compared to previous studies. We present a detailed statistical analysis of this data set with the Red MSX Source (RMS) catalog of massive young stellar sources to investigate the association of these bubbles with massive star formation. We particularly address the question of massive triggered star formation near infrared bubbles. We find a strong positional correlation of massive young stellar objects (MYSOs) and H II regions with Milky Way Project bubbles at separations of <2 bubble radii. As bubble sizes increase, a statistically significant overdensity of massive young sources emerges in the region of the bubble rims, possibly indicating the occurrence of triggered star formation. Based on numbers of bubble-associated RMS sources, we find that 67% {+-} 3% of MYSOs and (ultra-)compact H II regions appear to be associated with a bubble. We estimate that approximately 22% {+-} 2% of massive young stars may have formed as a result of feedback from expanding H II regions. Using MYSO-bubble correlations, we serendipitously recovered the location of the recently discovered massive cluster Mercer 81, suggesting the potential of such analyses for discovery of heavily extincted distant clusters.

  14. A SPITZER INFRARED SPECTROGRAPH STUDY OF DEBRIS DISKS AROUND PLANET-HOST STARS

    SciTech Connect

    Dodson-Robinson, Sarah E.; Beichman, C. A.; Carpenter, John M.; Bryden, Geoffrey

    2011-01-15

    Since giant planets scatter planetesimals within a few tidal radii of their orbits, the locations of existing planetesimal belts indicate regions where giant planet formation failed in bygone protostellar disks. Infrared observations of circumstellar dust produced by colliding planetesimals are therefore powerful probes of the formation histories of known planets. Here we present new Spitzer infrared spectrograph (IRS) spectrophotometry of 111 solar-type stars, including 105 planet hosts. Our observations reveal 11 debris disks, including two previously undetected debris disks orbiting HD 108874 and HD 130322. Combining the 32 {mu}m spectrophotometry with previously published MIPS photometry, we find that the majority of debris disks around solar-type stars have temperatures in the range 60 {approx}< T{sub dust} {approx}< 100 K. Assuming a dust temperature T{sub dust} = 70 K, which is representative of the nine debris disks detected by both IRS and MIPS, debris rings surrounding Sun-like stars orbit between 15 and 240 AU depending on the mean particle size. Our observations imply that the planets detected by radial-velocity searches formed within 240 AU of their parent stars. If any of the debris disks studied here have mostly large, blackbody emitting grains, their companion giant planets must have formed in a narrow region between the ice line and 15 AU.

  15. The atmopheric infrared sounder data products for weather prediction and climate studies

    NASA Astrophysics Data System (ADS)

    Pagano, T.; Chahine, M.; Aumann, H.; Lambrigtsen, B.; Fetzer, E.; Olsen, E.; Fishbein, E.; Thompson, C.; Lee, S. Y.

    The Atmospheric Infrared Sounder (AIRS) is a space based remote sensing instrument on the Earth Observing System Aqua Spacecraft. Aqua was launched in May of 2002 in a 1:30 pm equatorial crossing daytime ascending orbit. AIRS measures 2378 channels in the infrared from 3.7 um to 15.4 um and 4 channels in the Vis/NIR. The high number of infrared channels allows measurement of a wide range of data products useful for weather forecasting and climate studies. A major objective of the AIRS Project is to provide data products useful for improving weather forecasts. Current forecast models are very accurate and to improve upon these requires accuracies in products never achieved before. AIRS product requirements for improved forecasts include temperature profiles to 1K/km, humidity accuracies to 15%, sea surface temperature to 0.5K, and land surface temperature to 1K. Weather centers have not traditionally assimilated geophysical products, so the AIRS data products include a "Cloud Cleared Radiance" (CCR) product. The CCR products need to be accurate to 1K across the spectrum. The AIRS project has achieved the majority of the above requirements. Many of these parameters used for weather are also candidates for climate studies. The most fundamental product proposed to be used for climate studies are the AIRS calibrated radiances. It is from this product that all other products can be derived. However, with 2378 channels, each AIRS granule (file) is approximately 150 Mb in size making long term and global trending using the radiance products cumbersome. Several of the level 2 products are also candidates for climate studies including temperature layers and water vapor layers . To make climate studies easier for the user, the AIRS project has developed Level 3 products which include spatially and/or temporally aggregated AIRS data Level 2 products of various types. All AIRS Products that are currently available to the public can be obtained from the GSFC DAAC at http

  16. A Cerenkov source of high-power picosecond pulsed microwaves

    SciTech Connect

    Zhang, T.B.; Marshall, T.C.; Hirshfield, J.L. |

    1998-06-01

    One or more electron bunches passing along the axis of a dielectric-lined cylindrical waveguide are shown to emit picosecond pulses of high-power broad-band microwave radiation. The bunches can be generated by an S-band RF gun, and thus spaced from one another by 10.5 cm in a macropulse sequence, or a single more intense bunch can be generated using a laser-illuminated photocathode in the RF gun. Theory is developed for the excitation of TM{sub 0m} modes of this waveguide which propagate at the bunch velocity from Cerenkov radiation emitted by a single intense bunch. A train of picosecond coherent wakefield pulses is shown to follow the bunch, when the waveguide modes have nearly constant spacing in frequency. An example is shown for an alumina-lined waveguide with 10-nC 3--15-ps bunches having an initial energy of 6 MeV. Computations are presented of the mode spectrum of the radiation and its time structure. It is also shown that measurements of the mode spectrum, or of the energy loss of the bunch, can be used to infer the axial density profile of the bunch. Certain features of the theory are compared with the results of a preliminary experiment.

  17. Picosecond laser surface micropatterning of ceramics by optical fiber induction

    NASA Astrophysics Data System (ADS)

    Li, Jian; Ji, Lingfei; Hu, Yan; Wu, Yan; Yan, Yinzhou

    2015-06-01

    Parallel microgrooves and mesh structure with a line width of about 16 μm, which is much smaller than the diameter of the laser focus spot of 50 μm, are fabricated on Al2O3 ceramic surfaces by picosecond laser patterning with optical fiber induction. The patterned grooves are of high quality without burr, recasting or thermally induced cracks. Grain refinement of the groove surfaces caused by the rapid condensation and redeposition during picosecond laser irradiation with optical fiber induction improved the smoothness and mechanical strength of the grooves. Different patterns can be fabricated by adjusting the optical fiber layout, which is independent of the laser scanning direction. The regions etched by the laser are kept in near-field contact with the optical fibers when the laser beam passes through the fibers and irradiates the ceramic surface. This results in localized field enhancement between the transparent optic fiber and ceramic surface, which produces the precise microgrooves. The developed technique allows high-resolution micromachining of the surfaces of hard and brittle ceramic-type materials.

  18. Picosecond dynamics of benzophenone anion solvation

    SciTech Connect

    Lin, Y.; Jonah, C.D. )

    1993-01-14

    The dynamics of benzophenone anion solvation in alcohols are studied by pulse-radiolysis techniques. The solvation process is characterized by the blue shift of the transient absorption spectrum of the anion and is faster for the smaller alcohols. The anion is solvated more slowly than the electron in the same solvent, but the solvation times of both are similar to [tau][sub 2], the solvent dielectric relaxation time. The familiar phenomenological two-state model of solvation was found to be inappropriate for describing the anion solvation process. A multistate process appears to be a more appropriate description. The authors modeled the kinetics of the spectral relaxation. In most cases, nearly quantitative agreement between the calculated and observed spectra is achieved. The characteristic relaxation times for the alcohol solvents around the anions were also reproduced. 50 refs., 8 figs., 3 tabs.

  19. Picoseconds-Laser Modification of Thin Films

    SciTech Connect

    Gakovic, Biljana; Trtica, Milan; Batani, Dimitri; Desai, Tara; Redaelli, Renato

    2006-04-07

    The interaction of a Nd:YAG laser, pulse duration of 40 ps, with a titanium nitride (TiN) and tungsten-titanium (W-Ti) thin films deposited at silicon was studied. The peak intensity on targets was up to 1012 W/cm2. Results have shown that the TiN surface was modified, by the laser beam, with energy density of {>=}0.18 J/cm2 ({lambda}laser= 532 nm) as well as of 30.0 J/cm2 ({lambda}laser= 1064 nm). The W-Ti was surface modified with energy density of 5.0 J/cm2 ({lambda}laser= 532 nm). The energy absorbed from the Nd:YAG laser beam is partially converted to thermal energy, which generates a series of effects such as melting, vaporization of molten materials, dissociation and ionization of the vaporized material, appearance of plasma, etc. The following morphological changes of both targets were observed: (i) The appearance of periodic microstructures, in the central zone of the irradiated area, for laser irradiation at 532 nm. Accumulation of great number of laser pulses caused film ablation and silicon modification. (ii) Hole formation on the titanium nitride/silicon target was registered at 1064 nm. The process of the Nd:YAG laser interaction with both targets was accompanied by plasma formation above the target.

  20. Numerical analysis of laser ablation and damage in glass with multiple picosecond laser pulses.

    PubMed

    Sun, Mingying; Eppelt, Urs; Russ, Simone; Hartmann, Claudia; Siebert, Christof; Zhu, Jianqiang; Schulz, Wolfgang

    2013-04-01

    This study presents a novel numerical model for laser ablation and laser damage in glass including beam propagation and nonlinear absorption of multiple incident ultrashort laser pulses. The laser ablation and damage in the glass cutting process with a picosecond pulsed laser was studied. The numerical results were in good agreement with our experimental observations, thereby revealing the damage mechanism induced by laser ablation. Beam propagation effects such as interference, diffraction and refraction, play a major role in the evolution of the crater structure and the damage region. There are three different damage regions, a thin layer and two different kinds of spikes. Moreover, the electronic damage mechanism was verified and distinguished from heat modification using the experimental results with different pulse spatial overlaps.

  1. Absolute response of Fuji imaging plate detectors to picosecond-electron bunches

    SciTech Connect

    Zeil, K.; Kraft, S. D.; Jochmann, A.; Kroll, F.; Jahr, W.; Schramm, U.; Karsch, L.; Pawelke, J.; Hidding, B.; Pretzler, G.

    2010-01-15

    The characterization of the absolute number of electrons generated by laser wakefield acceleration often relies on absolutely calibrated FUJI imaging plates (IP), although their validity in the regime of extreme peak currents is untested. Here, we present an extensive study on the dependence of the sensitivity of BAS-SR and BAS-MS IP to picosecond electron bunches of varying charge of up to 60 pC, performed at the electron accelerator ELBE, making use of about three orders of magnitude of higher peak intensity than in prior studies. We demonstrate that the response of the IPs shows no saturation effect and that the BAS-SR IP sensitivity of 0.0081 photostimulated luminescence per electron number confirms surprisingly well data from previous works. However, the use of the identical readout system and handling procedures turned out to be crucial and, if unnoticed, may be an important error source.

  2. Picosecond Diffraction at the ESRF: How Far Have We Come and Where Are We Going?

    SciTech Connect

    Wulff, Michael; Kong Qingyu; Cammarata, Marco; Lo Russo, Manuela; Anfinrud, Philip; Schotte, Friedrich; Lorenc, Maciej; Ihee, Hyotcherl; Kim, Tae Kyu; Plech, Anton

    2007-01-19

    The realization of solution phase pump-probe diffraction experiments on beamline ID09B is described. The pink beam from a low-K in-vacuum undulator is used to study the structural dynamics of small molecules in solution to 100 picosecond time resolution and at atomic resolution. The X-ray chopper and the associated timing modes of the synchrotron are described. The dissociation of molecular iodine in liquid CCl4 is studied by single pulse diffraction. The data probe not only the iodine structures but also the solvent structure as the latter is thermally excited by the flow of energy from recombining iodine atoms. The low-q part of the diffraction spectra is a sensitive probe of the hydrodynamics of the solvent as a function of time.

  3. Middle infrared spectral studies of geologic materials in their natural state using photothermal beam deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Eastes, J. W.; Low, M. J. D.

    1984-04-01

    The use of a novel laboratory spectral technique is described for the recording of middle infrared (MIR) absorption spectra of natural surfaces with no sample preparation. Such a technique allows evaluation of spectral influences of surficial films such as weathering products, lichen cover or desert varnish on the spectra of the substrate geologic materials. In remote sensing applications the technique should provide spectral information more nearly representative of field conditions and may improve interpretation of thermal imagery. The technique, called photothermal beam deflection spectroscopy (PBDS) was originally developed for studies of surface chemistry in situations where it is impractical or impossible to separate surface layers from their substrate. In the present studies the spectral characteristics of natural rock and mineral surfaces have been examined.

  4. Study of varnish layers with optical coherence tomography in both visible and infrared domains

    NASA Astrophysics Data System (ADS)

    Latour, Gaël; Georges, Gaëlle; Siozade, Laure; Deumié, Carole; Echard, Jean-Philippe

    2009-07-01

    Optical Coherence Tomography (OCT) is an attractive technique to study works of art because it allows non-destructive and contactless analysis. In the case of musical instruments, the study of wood finishes could give interesting information as the thicknesses of the layers, the number of layers and the presence of fillers. A time-domain full-field OCT, achieving high resolution, is used in both visible and near infrared ranges to characterize semi-transparent layers containing scattering particles as charged varnish layers. We present OCT measurements on wood varnished with different coatings. We show that the detection of pigment particles is dependent of the spectral range and that both spectral domains allow to reach micrometer-scale spatial resolutions.

  5. Post-mortem cooling of the human head: an infrared thermology study.

    PubMed

    Khallaf, A; Williams, R W

    1991-01-01

    The post-mortem cooling of the human head, over the first fifteen hours after death, was measured by infrared thermology. A detailed temperature map of the head and face was obtained by the use of image processing techniques and the cooling behaviour of twelve preselected facial features was observed. The two main findings of the study were a difference in cooling pattern between the upper and the lower part of the head, and a consistency in the cooling pattern of the lower part of the head in all the cases studied. A comparison of various model fits to the raw data was undertaken and the "best" bodies, models and features were determined on a statistical basis. The formula that best fitted the raw data was a novel double application of Newton's law. The features with the least error in data fitting were the chin and zygoma; that with the most error was the mouth.

  6. Fourier transform infrared imaging analysis in discrimination studies of St. John's wort (Hypericum perforatum).

    PubMed

    Huck-Pezzei, V A; Pallua, J D; Pezzei, C; Bittner, L K; Schönbichler, S A; Abel, G; Popp, M; Bonn, G K; Huck, C W

    2012-10-01

    In the present study, Fourier transform infrared (FTIR) imaging and data analysis methods were combined to study morphological and molecular patterns of St. John's wort (Hypericum perforatum) in detail. For interpretation, FTIR imaging results were correlated with histological information gained from light microscopy (LM). Additionally, we tested several evaluation processes and optimized the methodology for use of complex FTIR microscopic images to monitor molecular patterns. It is demonstrated that the combination of the used spectroscopic method with LM enables a more distinct picture, concerning morphology and distribution of active ingredients, to be gained. We were able to obtain high-quality FTIR microscopic imaging results and to distinguish different tissue types with their chemical ingredients.

  7. Fourier transform infrared and Raman spectroscopy studies on magnetite/Ag/antibiotic nanocomposites

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Olena; Jurga-Stopa, Justyna; Coy, Emerson; Peplinska, Barbara; Pietralik, Zuzanna; Jurga, Stefan

    2016-02-01

    This article presents a study on the detection of antibiotics in magnetite/Ag/antibiotic nanocomposites using Fourier transform infrared (FTIR) and Raman spectroscopy. Antibiotics with different spectra of antimicrobial activities, including rifampicin, doxycycline, cefotaxime, and ceftriaxone, were studied. Mechanical mixtures of antibiotics and magnetite/Ag nanocomposites, as well as antibiotics and magnetite nanopowder, were investigated in order to identify the origin of FTIR bands. FTIR spectroscopy was found to be an appropriate technique for this task. The spectra of the magnetite/Ag/antibiotic nanocomposites exhibited very weak (for doxycycline, cefotaxime, and ceftriaxone) or even no (for rifampicin) antibiotic bands. This FTIR "invisibility" of antibiotics is ascribed to their adsorbed state. FTIR and Raman measurements show altered Csbnd O, Cdbnd O, and Csbnd S bonds, indicating adsorption of the antibiotic molecules on the magnetite/Ag nanocomposite structure. In addition, a potential mechanism through which antibiotic molecules interact with magnetite/Ag nanoparticle surfaces is proposed.

  8. Do GSM 900MHz signals affect cerebral blood circulation? A near-infrared spectrophotometry study

    NASA Astrophysics Data System (ADS)

    Wolf, Martin; Haensse, Daniel; Morren, Geert; Froehlich, Juerg

    2006-06-01

    Effects of GSM 900MHz signals (EMF) typical for a handheld mobile phone on the cerebral blood circulation were investigated using near-infrared spectrophotometry (NIRS) in a three armed (12W/kg, 1.2W/kg, sham), double blind, randomized crossover trial in 16 healthy volunteers. During exposure we observed borderline significant short term responses of oxyhemoglobin and deoxyhemoglobin concentration, which correspond to a decrease of cerebral blood flow and volume and were smaller than regular physiological changes. Due to the relatively high number of statistical tests, these responses may be spurious and require further studies. There was no detectable dose-response relation or long term response within 20min. The detection limit was a fraction of the regular physiological changes elicited by functional activation. Compared to previous studies using PET, NIRS provides a much higher time resolution, which allowed investigating the short term effects efficiently, noninvasively, without the use of radioactive tracers and with high sensitivity.

  9. Wide Field Infra-Red Survey Telescope (WFIRST) 2.4-Meter Mission Study

    NASA Technical Reports Server (NTRS)

    Content, D.; Aaron, K.; Alplanalp, L.; Anderson, K.; Capps, R.; Chang, Z.; Dooley, J.; Egerman, R.; Goullioud, R.; Klein, D.; Kruk, J.; Kuan, G.; Melton, M.; Ruffa, J.; Underhill, M.; Buren, D. Van

    2013-01-01

    The most recent study of the Wide Field Infrared Survey Telescope (WFIRST) mission is based on reuse of an existing 2.4m telescope. This study was commissioned by NASA to examine the potential science return and cost effectiveness of WFIRST by using this significantly larger aperture telescope. We review the science program envisioned by the WFIRST 2012-2013 Science Definition Team (SDT), an overview of the mission concept, and the telescope design and status. Comparisons against the previous 1.3m and reduced cost 1.1m WFIRST design concepts are discussed. A significant departure from past point designs is the option for serviceability and the geostationary orbit location which enables servicing and replacement instrument insertion later during mission life. Other papers at this conference provide more in depth discussion of the wide field instrument and the optional exoplanet imaging coronagraph instrument.

  10. A far-infrared radiative closure study in the Arctic: Application to water vapor

    NASA Astrophysics Data System (ADS)

    Delamere, J. S.; Clough, S. A.; Payne, V. H.; Mlawer, E. J.; Turner, D. D.; Gamache, R. R.

    2010-09-01

    Far-infrared (λ > 15.0 μm) (far-IR) radiative processes provide a large fraction of Earth's outgoing longwave radiation and influence upper tropospheric vertical motion. Water vapor, because of its abundance and strong absorption properties over an extended spectral range, is the primary source of these radiative processes. Historically, the lack of spectrally resolved radiometric instruments and the opacity of the lower atmosphere have precluded extensive studies of far-IR water vapor absorption properties. The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program has organized a series of field experiments, the Radiative Heating in Underexplored Bands Campaigns (RHUBC), to address this deficiency. The first phase of RHUBC took place in 2007 at the ARM North Slope of Alaska Climate Research Facility. Measurements taken before and during this campaign have provided the basis for a clear-sky radiative closure study aimed at reducing key uncertainties associated with far-IR radiative transfer models. Extended-range Atmospheric Emitted Radiance Interferometer infrared radiance observations taken in clear sky conditions were compared against calculations from the Line-By-Line Radiative Transfer Model. The water vapor column amounts used in these calculations were retrieved from 183 GHz radiometer measurements. The uncertainty in these integrated water vapor retrievals is approximately 2%, a notable improvement over past studies. This far-IR radiative closure study resulted in an improvement to the Mlawer-Tobin Clough-Kneiyzs-Davies (MT_CKD) water vapor foreign continuum model and updates to numerous, far-IR water vapor line parameters from their values in the circa 2006 version of the HITRAN molecular line parameter database.

  11. Active mode-locking of mid-infrared quantum cascade lasers with short gain recovery time.

    PubMed

    Wang, Yongrui; Belyanin, Alexey

    2015-02-23

    We investigate the dynamics of actively modulated mid-infrared quantum cascade lasers (QCLs) using space- and time-domain simulations of coupled density matrix and Maxwell equations with resonant tunneling current taken into account. We show that it is possible to achieve active mode locking and stable generation of picosecond pulses in high performance QCLs with a vertical laser transition and a short gain recovery time by bias modulation of a short section of a monolithic Fabry-Perot cavity. In fact, active mode locking in QCLs with a short gain recovery time turns out to be more robust to the variation of parameters as compared to previously studied lasers with a long gain recovery time. We investigate the effects of spatial hole burning and phase locking on the laser output.

  12. Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

    NASA Astrophysics Data System (ADS)

    Berg, Christopher Michael

    An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

  13. Vibrational dynamics of azide-derivatized amino acids studied by nonlinear infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Okuda, Masaki; Ohta, Kaoru; Tominaga, Keisuke

    2015-06-01

    Recently, biomolecules which are labeled by azide or thiocyanate groups in solutions and proteins have been studied to examine microscopic environment around a solute by nonlinear infrared (IR) spectroscopy. In this study, we have performed two-dimensional infrared (2D-IR) spectroscopy to investigate the vibrational frequency fluctuations of two different azide-derivatized amino acids, Ala (N3-Ala) and Pro (N3-Pro), and N3- in water. From the 2D-IR experiments, it was found that the frequency-frequency time correlation function (FFTCF) of solute can be modeled by a delta function plus an exponential function and constant. FFTCF for each probe molecule has a decay component of about 1 ps, and this result suggests that the stretching mode of the covalently bonded azide group is sensitive to the fluctuations of hydrogen bond network system, as found in previous studies of N3- in water. In contrast to FFTCF of N3-, FFTCF of the azide-derivatized amino acids contains static component. This static component may reflect dynamics of water affected by the solutes or the structural fluctuations of the solute itself. We also performed the IR pump-probe measurements for the probe molecules in water in order to investigate vibrational energy relaxation (VER) and reorientational relaxation. It was revealed that the charge fluctuations in the azide group are significant for the VER of this mode in water, reflecting that the VER rate of N3- is faster than those of the azide-derivatized amino acids. While the behaviors of the anisotropy decay of N3-Ala and N3- are similar to each other, the anisotropy decay of N3-Pro contains much slower decaying component. By considering the structural difference around the vibrational probe between N3-Ala and N3-Pro, it is suggested that the structural freedom of the probe molecules can affect the reorientational processes.

  14. Infrared dermal thermography on diabetic feet soles to predict ulcerations: a case study

    NASA Astrophysics Data System (ADS)

    Liu, Chanjuan; van der Heijden, Ferdi; Klein, Marvin E.; van Baal, Jeff G.; Bus, Sicco A.; van Netten, Jaap J.

    2013-03-01

    Diabetic foot ulceration is a major complication for patients with diabetes mellitus. If not adequately treated, these ulcers may lead to foot infection, and ultimately to lower extremity amputation, which imposes a major burden to society and great loss in health-related quality of life for patients. Early identification and subsequent preventive treatment have proven useful to limit the incidence of foot ulcers and lower extremity amputation. Thus, the development of new diagnosis tools has become an attractive option. The ultimate objective of our project is to develop an intelligent telemedicine monitoring system for frequent examination on patients' feet, to timely detect pre-signs of ulceration. Inflammation in diabetic feet can be an early and predictive warning sign for ulceration, and temperature has been proven to be a vicarious marker for inflammation. Studies have indicated that infrared dermal thermography of foot soles can be one of the important parameters for assessing the risk of diabetic foot ulceration. This paper covers the feasibility study of using an infrared camera, FLIR SC305, in our setup, to acquire the spatial thermal distribution on the feet soles. With the obtained thermal images, automated detection through image analysis was performed to identify the abnormal increased/decreased temperature and assess the risk for ulceration. The thermography for feet soles of patients with diagnosed diabetic foot complications were acquired before the ordinary foot examinations. Assessment from clinicians and thermography were compared and follow-up measurements were performed to investigate the prediction. A preliminary case study will be presented, indicating that dermal thermography in our proposed setup can be a screening modality to timely detect pre-signs of ulceration.

  15. NO binding kinetics in myoglobin investigated by picosecond Fe K-edge absorption spectroscopy

    PubMed Central

    Silatani, Mahsa; Lima, Frederico A.; Penfold, Thomas J.; Rittmann, Jochen; Reinhard, Marco E.; Rittmann-Frank, Hannelore M.; Borca, Camelia; Grolimund, Daniel; Milne, Christopher J.; Chergui, Majed

    2015-01-01

    Diatomic ligands in hemoproteins and the way they bind to the active center are central to the protein’s function. Using picosecond Fe K-edge X-ray absorption spectroscopy, we probe the NO-heme recombination kinetics with direct sensitivity to the Fe-NO binding after 532-nm photoexcitation of nitrosylmyoglobin (MbNO) in physiological solutions. The transients at 70 and 300 ps are identical, but they deviate from the difference between the static spectra of deoxymyoglobin and MbNO, showing the formation of an intermediate species. We propose the latter to be a six-coordinated domed species that is populated on a timescale of ∼200 ps by recombination with NO ligands. This work shows the feasibility of ultrafast pump–probe X-ray spectroscopic studies of proteins in physiological media, delivering insight into the electronic and geometric structure of the active center. PMID:26438842

  16. Measurements of Electron Transport in Foils Irradiated with a Picosecond Time Scale Laser Pulse

    SciTech Connect

    Brown, C. R. D.; Hoarty, D. J.; James, S. F.; Swatton, D.; Hughes, S. J.; Morton, J. W.; Guymer, T. M.; Hill, M. P.; Chapman, D. A.; Andrew, J. E.; Comley, A. J.; Shepherd, R.; Dunn, J.; Chen, H.; Schneider, M.; Brown, G.; Beiersdorfer, P.; Emig, J.

    2011-05-06

    The heating of solid foils by a picosecond time scale laser pulse has been studied by using x-ray emission spectroscopy. The target material was plastic foil with a buried layer of a spectroscopic tracer material. The laser pulse length was either 0.5 or 2 ps, which resulted in a laser irradiance that varied over the range 10{sup 16}-10{sup 19} W/cm{sup 2}. Time-resolved measurements of the buried layer emission spectra using an ultrafast x-ray streak camera were used to infer the density and temperature conditions as a function of laser parameters and depth of the buried layer. Comparison of the data to different models of electron transport showed that they are consistent with a model of electron transport that predicts the bulk of the target heating is due to return currents.

  17. Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Theodorakos, I.; Zergioti, I.; Vamvakas, V.; Tsoukalas, D.; Raptis, Y. S.

    2014-01-01

    In this work, a picosecond diode pumped solid state laser and a nanosecond Nd:YAG laser have been used for the annealing and the partial nano-crystallization of an amorphous silicon layer. These experiments were conducted as an alternative/complementary to plasma-enhanced chemical vapor deposition method for fabrication of micromorph tandem solar cell. The laser experimental work was combined with simulations of the annealing process, in terms of temperature distribution evolution, in order to predetermine the optimum annealing conditions. The annealed material was studied, as a function of several annealing parameters (wavelength, pulse duration, fluence), as far as it concerns its structural properties, by X-ray diffraction, SEM, and micro-Raman techniques.

  18. Patterned graphene ablation and two-photon functionalization by picosecond laser pulses in ambient conditions

    SciTech Connect

    Bobrinetskiy, I. I. Otero, N.; Romero, P. M.; Emelianov, A. V.

    2015-07-27

    Direct laser writing is a technology with excellent prospects for mask-less processing of carbon-based nanomaterials, because of the wide range of photoinduced reactions that can be performed on large surfaces with submicron resolution. In this paper, we demonstrate the use of picoseconds laser pulses for one-step ablation and functionalization of graphene. Varying the parameters of power, pulse frequency, and speed, we demonstrated the ablation down to 2 μm width and up to mm-long lines as well as functionalization with spatial resolution less than 1 μm with linear speeds in the range of 1 m/s. Raman and atomic-force microscopy studies were used to indicate the difference in modified graphene states and correlation to the changes in optical properties.

  19. Laser Processing of Thin Glass Printed Circuit Boards with a Picosecond Laser at 515 nm Wavelength

    NASA Astrophysics Data System (ADS)

    Plat, K.; Witzendorff, P. v.; Suttmann, O.; Overmeyer, L.

    High temperature applications of printed circuit boards (PCB)require materials with specifically adapted properties. Hence, conventional electrically isolating glass fiber and epoxy-resin materials have to be replaced by thin borosilicate glass.Therefore, an industrially suitable process to remove the metal coatings from the brittle thin glass has to be developed. Laser processing has the advantage of individualization for the production of customer-specific PCBs. Thus, laser ablation of metal coatings for electrical isolation is investigated with different material composites based on thin glass.The study aims to identify a laser process for a picosecond laser source with 515 nm wavelength to perform the process without damaging the glass substrate with a high throughput.

  20. 355, 532, and 1064 nm picosecond laser interaction with grass tissues

    NASA Astrophysics Data System (ADS)

    Kim, Jaehun; Ki, Hyungson

    2012-12-01

    In this article, we investigate how 355, 532, and 1064 nm picosecond lasers interact with grass tissues. We have identified five interaction regimes, and based on this classification, interaction maps have been constructed from a systematic experiment. The optical properties of light absorbing grass constituents are studied theoretically in order to understand how and how much light is absorbed by grass tissues. Scanning electron microscopy and optical microscopy are employed for observing morphological and structural changes of grass tissues. To the best of the authors' knowledge, this is the first investigation into laser interaction with plant leaves and reveals some fundamental findings regarding how a laser interacts with grass tissues and how plant leaves can be processed using lasers.

  1. Sub-picosecond streak camera measurements at LLNL: From IR to x-rays

    SciTech Connect

    Kuba, J; Shepherd, R; Booth, R; Steward, R; Lee, E W; Cross, R R; Springer, P T

    2003-12-21

    An ultra fast, sub-picosecond resolution streak camera has been recently developed at the LLNL. The camera is a versatile instrument with a wide operating wavelength range. The temporal resolution of up to 300 fs can be achieved, with routine operation at 500 fs. The streak camera has been operated in a wide wavelength range from IR to x-rays up to 2 keV. In this paper we briefly review the main design features that result in the unique properties of the streak camera and present its several scientific applications: (1) Streak camera characterization using a Michelson interferometer in visible range, (2) temporally resolved study of a transient x-ray laser at 14.7 nm, which enabled us to vary the x-ray laser pulse duration from {approx}2-6 ps by changing the pump laser parameters, and (3) an example of a time-resolved spectroscopy experiment with the streak camera.

  2. Investigation on Soft X-Ray Lasers with a Picosecond-Laser-Irradiated Gas Puff Target

    SciTech Connect

    Fiedorowiez, H; Bartnik, A; Jarocki, R; Rakowski, R; Dunn, J; Smith, R F; Hunter, J; Hilsen, J; Shlyaptsev, V N

    2002-10-09

    We present results of experimental studies on transient gain soft x-ray lasers with a picosecond-laser-irradiated gas puff target. The target in a form of an elongated gas sheet is formed by pulsed injection of gas through a slit nozzle using a high-pressure electromagnetic valve developed and characterized at the Institute of Optoelectronics. The x-ray laser experiments were performed at the Lawrence Livermore National Laboratory using the tabletop Compact Multipulse Terawatt (COMET) laser to irradiate argon, krypton or xenon gas puff targets. Soft x-ray lasing in neon-like argon on the 3p-3s transition at 46.9 nm and the 3d-3p transition at 45.1 nm have been demonstrated, however, no amplification for nickel-like krypton or xenon was observed. Results of the experiments are presented and discussed.

  3. Picosecond Neutron Yields from Ultra-Intense Laser-Target Interactions

    NASA Astrophysics Data System (ADS)

    Ellison, C. Leland; Fuchs, Julien

    2009-11-01

    High-flux neutron sources for neutron imaging and materials analysis applications have typically been provided by accelerator-based (Spallation Neutron Source) and reactor-based (High Flux Isotope Reactor) neutron sources. A novel approach is to use ultra-intense (> 10^18 W/cm^2) laser-target interactions to generate picosecond, collimated neutrons. Here we examine the feasibility of a source based on current (LULI) and upcoming laser facility capabilities. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. The parameters of the deuteron beam are well understood from laser-plasma and laser-target studies relevant to fast-ignition fusion. Expected neutron yields are presented in comparison to conventional neutron sources, previous experimental neutron yields, and within the context of neutron shielding safety requirements.

  4. Towards a table-top microscope for nanoscale magnetic imaging using picosecond thermal gradients

    PubMed Central

    Bartell, J. M.; Ngai, D. H.; Leng, Z.; Fuchs, G. D.

    2015-01-01

    Research advancement in magnetoelectronics is challenged by the lack of a table-top magnetic measurement technique with the simultaneous temporal and spatial resolution necessary for characterizing magnetization dynamics in devices of interest, such as magnetic memory and spin torque oscillators. Although magneto-optical microscopy provides superb temporal resolution, its spatial resolution is fundamentally limited by optical diffraction. To address this challenge, we study heat rather than light as a vehicle to stroboscopically transduce a local magnetic moment into an electrical signal while retaining picosecond temporal resolution. Using this concept, we demonstrate spatiotemporal magnetic microscopy using the time-resolved anomalous Nernst effect (TRANE). Experimentally and with supporting numerical calculations, we find that TRANE microscopy has temporal resolution below 30 ps and spatial resolution determined by the area of thermal excitation. Based on these findings, we suggest a route to exceed the limits imposed by far-field optical diffraction. PMID:26419515

  5. Morphology and crystalline phase characteristics of α-GST films irradiated by a picosecond laser

    NASA Astrophysics Data System (ADS)

    Zhao, J. J.; Liu, F. R.; Han, X. X.; Bai, N.; Wan, Y. H.; Lin, X.; Liu, F.

    2014-01-01

    The morphology and crystalline phase characteristics of amorphous Ge2Sb2Te5 films irradiated by a picosecond laser were investigated by 3D surface profiler, atomic force microscopy (AFM) and transmission electron microscopy (TEM) integrated with selected area electron diffraction (SAED). The laser irradiated spot was divided into strong ablation area, gentle ablation area, melting area and irradiation area. By theoretical calculation, the ablation and melting thresholds were determined to be 173.05 mJ cm-2 and 99.19 mJ cm-2 respectively. Meantime, the local fine morphologies of the ablation and melting areas were shown and analyzed. We also studied the irradiation area which was made up by the non-phase-change area and phase-change area. In the phase-change area, crystalline phase was determined to be face-centered cubic structure and crystalline phase characteristics for films with different thicknesses were discussed.

  6. High-speed laser-assisted cutting of strong transparent materials using picosecond Bessel beams

    NASA Astrophysics Data System (ADS)

    Bhuyan, M. K.; Jedrkiewicz, O.; Sabonis, V.; Mikutis, M.; Recchia, S.; Aprea, A.; Bollani, M.; Trapani, P. Di

    2015-08-01

    We report single-pass cutting of strong transparent glass materials of 700 μm thickness with a speed up to 270 mm/s using single-shot nanostructuring technique exploiting picosecond, zero-order Bessel beams at laser wavelength of 1030 nm. Particularly, we present results of a systematic study of cutting of tempered glass which has high resistance to thermal and mechanical shocks due to the inhomogeneous material properties along its thickness, and homogeneous glass that identify a unique focusing geometry and a finite pitch dependency, for which cutting with high quality and high reproducibility can be achieved. These results represent a significant advancement in the field of high-speed cutting of technologically important transparent materials.

  7. Low-order harmonic generation in metal ablation plasmas in nanosecond and picosecond laser regimes

    SciTech Connect

    Lopez-Arias, M.; Oujja, M.; Sanz, M.; Castillejo, M.; Ganeev, R. A.; Boltaev, G. S.; Satlikov, N. Kh.; Tugushev, R. I.; Usmanov, T.

    2012-02-15

    Low-order harmonics, third and fifth, of IR (1064 nm) laser emission have been produced in laser ablation plasmas of the metals manganese, copper and silver. The harmonics were generated in a process triggered by laser ablation followed by frequency up-conversion of a fundamental laser beam that propagates parallel to the target surface. These studies were carried out in two temporal regimes by creating the ablation plasma using either nanosecond or picosecond pulses and then probing the plasma plume with pulses of the same duration. The spatiotemporal behavior of the generated harmonics was characterized and reveals the distinct composition and dynamics of the plasma species that act as nonlinear media, allowing the comparison of different processes that control the generation efficiency. These results serve to guide the choice of laser ablation plasmas to be used for efficient high harmonic generation of laser radiation.

  8. Ion attachment mass spectrometry combined with infrared image furnace for thermal analysis: evolved gas analysis studies.

    PubMed

    Kitahara, Yuki; Takahashi, Seiji; Kuramoto, Noriyuki; Sala, Martin; Tsugoshi, Takahisa; Sablier, Michel; Fujii, Toshihiro

    2009-04-15

    A well-established ion attachment mass spectrometer (IAMS) is combined with an in-house single-atom infrared image furnace (IIF) specifically for thermal analysis studies. Besides the detection of many chemical species at atmospheric pressure, including free radical intermediates, the ion attachment mass spectrometer can also be used for the analysis of products emanating from temperature-programmed pyrolysis. The performance and applicability of the IIF-IAMS is illustrated with poly(tetrafluoroethylene) (PTFE) samples. The potential of the system for the analysis of oxidative pyrolysis is also considered. Temperature-programmed decomposition of PTFE gave constant slopes of the plots of temperature versus signal intensity in a defined region and provided an apparent activation energy of 28.8 kcal/mol for the PTFE decomposition product (CF(2))(3). A brief comparison with a conventional pyrolysis gas chromatography/mass spectrometry system is also given.

  9. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    SciTech Connect

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S. Michael; Lokitz, Bradley S.; Minko, Sergiy; Hinrichs, Karsten

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights into the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.

  10. Infrared Spectral Studies of the Thermally-Driven Chemistry Present on Icy Satellites

    NASA Technical Reports Server (NTRS)

    Loeffler, Mark J.; Hudson, Reggie L.

    2012-01-01

    Remote sensing of Jupiters icy satellites has revealed that even though their surfaces arc composed mostly of water ice, molecules such as SO2, CO2, H2O2. O2, and O3 also are present. On Europa, a high radiation flux is believed to play a role in the formation of many of the minor species detected, and numerous laboratory studies have been devoted to explore this hypothesis. In this presentation we will discuss some of our recent research on another alteration pathway, thermally-driven chemical reactions, which are also important for understanding the chemical evolution of Europa's surface and sub-surface ices. We will focus on the infrared spectra of and reactions between H2O, SO2 and H2O2, at 80 - 130 K.

  11. NMR and Infrared Study of Thermal Oxidation of cis-1, 4-Polybutadiene

    NASA Technical Reports Server (NTRS)

    Gemmer, Robert V.; Golub, Morton A.

    1978-01-01

    A study of the microstructural changes occuring in CB during thermal, uncatalyzed oxidation was carried out. Although the oxidation of CB is accompanied by extensive crosslinking with attendant insolubilization, it was found possible to follow the oxidation of solid CB directly with C-13 NMR spectroscopy. The predominant products appearing in the C-13 NMR spectra of oxidized CB are epoxides. The presence of lesser amounts of alcohols, peroxides, and carbonyl structures was adduced from complementary infrared and NMR spectra of soluble extracts obtained from the oxidized, crosslinked CB. This distribution of functional groups contrasts with that previously reported for the autooxidation of 1,4-polyisoprene. The difference was rationalized in terms of the relative stabilities of intermediate radical species involved in the autoxidation of CB and 1,4-polyisoprene.

  12. Opening of an icosahedral boron framework: A combined infrared spectroscopic and computational study

    NASA Astrophysics Data System (ADS)

    Fagiani, Matias R.; Liu Zeonjuk, L.; Esser, Tim K.; Gabel, Detlef; Heine, Thomas; Asmis, Knut R.; Warneke, Jonas

    2015-04-01

    The opening of an icosahderal boron cage in the periodinated closo-dodecaborate B12I122- upon deiodination is studied using cryogenic ion trap vibrational spectroscopy combined with electronic structure calculations. Comparison of simulated vibrational spectra to the infrared photodissociation spectra of messenger-tagged B12I122- and B12In- (n = 7-9) formed by skimmer collision induced dissociation shows that the larger clusters absorb exclusively below 975 cm-1 and hence exhibit quasi-icosahedral B12-cage structures, while the higher energy absorptions in-between 1000 and 1300 cm-1 observed for n = 7 can only be recovered by considering a breakup of the icosahedral cage upon deiodination from n = 8 to n = 7.

  13. Prediction of Fundamental Vibrational Frequencies and Infrared Intensities: a Benchmark Study

    NASA Astrophysics Data System (ADS)

    Vázquez, Juana; Harding, Michael E.; Stanton, John F.

    2011-06-01

    In this work we investigate the performance of second-order vibrational perturbation theory (VPT2) using force fields computed at the fc-CCSD(T) level in conjunction with different double-, triple-, and quadruple-ζ basis sets for the prediction of fundamental vibrational frequencies and infrared intensities. A benchmark study comprising more than thirty small and medium sized molecules illustrates the accuracy and limitations of the presented scheme. Atomic natural orbital (ANOY, Y=0,1,2) [J. Almlöf and P. R. Taylor, J. Chem. Phys. 86, 4070 (1987)] and correlation-consistent (cc-pVXZ, X=D,T,Q) [T. H. Dunning, Jr., J. Chem. Phys. 90, 1007 (1989)] basis sets.

  14. Infrared and density functional theory studies of formic acid hydrate clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2016-08-01

    Infrared absorption spectra of formic acid hydrate clusters (HCOOH)m(H2O)n have been measured in noble gas matrices (Ar and Kr). The concentration dependence of the spectra and the comparison with a previous experimental study on HCOOH(H2O) and HCOOH(H2O)2 [Geoge et al., Spectrochim. Acta, Part A 60 (2004) 3225] led to the identification of large clusters. Density functional theory calculations at the B3LYP-DCP/6-31+G(2d,2p) level were carried out to determine the anharmonic vibrational properties of the clusters, enabling a consistent assignment of the observed vibrational peaks to specific clusters.

  15. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    DOE PAGESBeta

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S. Michael; et al

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights intomore » the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.« less

  16. A CO LINE AND INFRARED CONTINUUM STUDY OF THE ACTIVE STAR-FORMING COMPLEX W51

    SciTech Connect

    Kang, Miju; Lee, Youngung; Choi, Minho; Bieging, John H.; Kulesa, Craig A.; Peters, William L.

    2010-09-15

    We present the results of an extensive observational study of the active star-forming complex W51 that was observed in the J = 2 - 1 transition of the {sup 12}CO and {sup 13}CO molecules over a 1.{sup 0}25 x 1.{sup 0}00 region with the University of Arizona Heinrich Hertz Submillimeter Telescope. We use a statistical equilibrium code to estimate physical properties of the molecular gas. We compare the molecular cloud morphology with the distribution of infrared (IR) and radio continuum sources and find associations between molecular clouds and young stellar objects (YSOs) listed in Spitzer IR catalogs. The ratios of CO lines associated with H II regions are different from the ratios outside the active star-forming regions. We present evidence of star formation triggered by the expansion of the H II regions and by cloud-cloud collisions. We estimate that about 1% of the cloud mass is currently in YSOs.

  17. A CO Line and Infrared Continuum Study of the Active Star-forming Complex W51

    NASA Astrophysics Data System (ADS)

    Kang, Miju; Bieging, John H.; Kulesa, Craig A.; Lee, Youngung; Choi, Minho; Peters, William L.

    2010-09-01

    We present the results of an extensive observational study of the active star-forming complex W51 that was observed in the J = 2 - 1 transition of the 12CO and 13CO molecules over a 1fdg25 × 1fdg00 region with the University of Arizona Heinrich Hertz Submillimeter Telescope. We use a statistical equilibrium code to estimate physical properties of the molecular gas. We compare the molecular cloud morphology with the distribution of infrared (IR) and radio continuum sources and find associations between molecular clouds and young stellar objects (YSOs) listed in Spitzer IR catalogs. The ratios of CO lines associated with H II regions are different from the ratios outside the active star-forming regions. We present evidence of star formation triggered by the expansion of the H II regions and by cloud-cloud collisions. We estimate that about 1% of the cloud mass is currently in YSOs.

  18. Infrared laser thermal fusion of blood vessels: preliminary ex vivo tissue studies.

    PubMed

    Cilip, Christopher M; Rosenbury, Sarah B; Giglio, Nicholas; Hutchens, Thomas C; Schweinsberger, Gino R; Kerr, Duane; Latimer, Cassandra; Nau, William H; Fried, Nathaniel M

    2013-05-01

    Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical, and ultrasonic devices have recently replaced the use of sutures and mechanical clips (which leave foreign objects in the body) for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create an undesirably large collateral zone of thermal damage and tissue necrosis. We explore an alternative energy-based technology, infrared lasers, for rapid and precise thermal coagulation and fusion of the blood vessel walls. Seven near-infrared lasers (808, 980, 1075, 1470, 1550, 1850 to 1880, and 1908 nm) were tested during preliminary tissue studies. Studies were performed using fresh porcine renal vessels, ex vivo, with native diameters of 1 to 6 mm, and vessel walls flattened to a total thickness of 0.4 mm. A linear beam profile was applied normal to the vessel for narrow, full-width thermal coagulation. The laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength demonstrated the capability of sealing a wide range of blood vessels from 1 to 6 mm diameter with burst strengths of 578 ± 154, 530 ± 171, and 426 ± 174  mmHg for small, medium, and large vessel diameters, respectively. Lateral thermal coagulation zones (including the seal) measured 1.0 ± 0.4  mm on vessels sealed at this wavelength. Other laser wavelengths (1550, 1850 to 1880, and 1908 nm) were also capable of sealing vessels, but were limited by lower vessel seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels (>4  mm outer diameter). PMID:23640080

  19. Infrared laser thermal fusion of blood vessels: preliminary ex vivo tissue studies.

    PubMed

    Cilip, Christopher M; Rosenbury, Sarah B; Giglio, Nicholas; Hutchens, Thomas C; Schweinsberger, Gino R; Kerr, Duane; Latimer, Cassandra; Nau, William H; Fried, Nathaniel M

    2013-05-01

    Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical, and ultrasonic devices have recently replaced the use of sutures and mechanical clips (which leave foreign objects in the body) for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create an undesirably large collateral zone of thermal damage and tissue necrosis. We explore an alternative energy-based technology, infrared lasers, for rapid and precise thermal coagulation and fusion of the blood vessel walls. Seven near-infrared lasers (808, 980, 1075, 1470, 1550, 1850 to 1880, and 1908 nm) were tested during preliminary tissue studies. Studies were performed using fresh porcine renal vessels, ex vivo, with native diameters of 1 to 6 mm, and vessel walls flattened to a total thickness of 0.4 mm. A linear beam profile was applied normal to the vessel for narrow, full-width thermal coagulation. The laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength demonstrated the capability of sealing a wide range of blood vessels from 1 to 6 mm diameter with burst strengths of 578 ± 154, 530 ± 171, and 426 ± 174  mmHg for small, medium, and large vessel diameters, respectively. Lateral thermal coagulation zones (including the seal) measured 1.0 ± 0.4  mm on vessels sealed at this wavelength. Other laser wavelengths (1550, 1850 to 1880, and 1908 nm) were also capable of sealing vessels, but were limited by lower vessel seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels (>4  mm outer diameter).

  20. Infrared cross-sections and integrated band intensities of propylene: Temperature-dependent studies

    NASA Astrophysics Data System (ADS)

    Es-sebbar, Et-touhami; Alrefae, Majed; Farooq, Aamir

    2014-01-01

    Propylene, a by-product of biomass burning, thermal cracking of hydrocarbons and incomplete combustion of fossil fuels, is a ubiquitous molecule found in the environment and atmosphere. Accurate infrared (IR) cross-sections and integrated band intensities of propylene are essential for quantitative measurements and atmospheric modeling. We measured absolute IR cross-sections of propylene using Fourier Transform Infrared (FTIR) Spectroscopy over the wavenumber range of 400-6500 cm-1 and at gas temperatures between 296 and 460 K. We recorded these spectra at spectral resolutions ranging from 0.08 to 0.5 cm-1 and measured the integrated band intensities for a number of vibrational bands in certain spectral regions. We then compared the integrated band intensities measured at room temperature with values derived from the National Institute of Standards and Technology (NIST) and the Pacific Northwest National Laboratory (PNNL) databases. Our results agreed well with the results reported in the two databases with a maximum deviation of about 4%. The peak cross-sections for the primary bands decreased by about 20-54% when the temperature increased from 296 to 460 K. Moreover, we determined the integrated band intensities as a function of temperature for certain features in various spectral regions; we found no significant temperature dependence over the range of temperatures considered here. We also studied the effect of temperature on absorption cross-section using a Difference Frequency Generation (DFG) laser system. We compared the DFG results with those obtained from the FTIR study at certain wavenumbers over the 2850-2975 cm-1 range and found a reasonable agreement with less than 10% discrepancy.

  1. Infrared studies of the reaction of methanesulfonic acid with trimethylamine on surfaces.

    PubMed

    Nishino, Noriko; Arquero, Kristine D; Dawson, Matthew L; Finlayson-Pitts, Barbara J

    2014-01-01

    Organosulfur compounds generated from a variety of biological as well as anthropogenic sources are oxidized in air to form sulfuric acid and methanesulfonic acid (MSA). Both of these acids formed initially in the gas phase react with ammonia and amines in air to form and grow new particles, which is important for visibility, human health and climate. A competing sink is deposition on surfaces in the boundary layer. However, relatively little is known about reactions after they deposit on surfaces. We report here diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies of the reaction of MSA with trimethylamine (TMA) on a silicon powder at atmospheric pressure in synthetic air and at room temperature, either in the absence or in the presence of water vapor. In both cases, DRIFTS spectra of the product surface species are essentially the same as the transmission spectrum obtained for trimethylaminium methanesulfonate, indicating the formation of the salt on the surface with a lower limit to the reaction probability of γ > 10(-6). To the best of our knowledge, this is the first infrared study to demonstrate this chemistry from the heterogeneous reaction of MSA with an amine on a surface. This heterogeneous chemistry appears to be sufficiently fast that it could impact measurements of gas-phase amines through reactions with surface-adsorbed acids on sampling lines and inlets. It could also represent an additional sink for amines in the boundary layer, especially at night when the gas-phase reactions of amines with OH radical and ozone are minimized.

  2. Infrared laser thermal fusion of blood vessels: preliminary ex vivo tissue studies

    NASA Astrophysics Data System (ADS)

    Cilip, Christopher M.; Rosenbury, Sarah B.; Giglio, Nicholas; Hutchens, Thomas C.; Schweinsberger, Gino R.; Kerr, Duane; Latimer, Cassandra; Nau, William H.; Fried, Nathaniel M.

    2013-05-01

    Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical, and ultrasonic devices have recently replaced the use of sutures and mechanical clips (which leave foreign objects in the body) for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create an undesirably large collateral zone of thermal damage and tissue necrosis. We explore an alternative energy-based technology, infrared lasers, for rapid and precise thermal coagulation and fusion of the blood vessel walls. Seven near-infrared lasers (808, 980, 1075, 1470, 1550, 1850 to 1880, and 1908 nm) were tested during preliminary tissue studies. Studies were performed using fresh porcine renal vessels, ex vivo, with native diameters of 1 to 6 mm, and vessel walls flattened to a total thickness of 0.4 mm. A linear beam profile was applied normal to the vessel for narrow, full-width thermal coagulation. The laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength demonstrated the capability of sealing a wide range of blood vessels from 1 to 6 mm diameter with burst strengths of 578±154, 530±171, and 426±174 mmHg for small, medium, and large vessel diameters, respectively. Lateral thermal coagulation zones (including the seal) measured 1.0±0.4 mm on vessels sealed at this wavelength. Other laser wavelengths (1550, 1850 to 1880, and 1908 nm) were also capable of sealing vessels, but were limited by lower vessel seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels (>4 mm outer diameter).

  3. An Infrared Through Radio Study of the Properties and Evolution of IRDC Clumps

    NASA Astrophysics Data System (ADS)

    Battersby, Cara; Bally, John; Jackson, James M.; Ginsburg, Adam; Shirley, Yancy L.; Schlingman, Wayne; Glenn, Jason

    2010-09-01

    We examine the physical properties and evolutionary stages of a sample of 17 clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared, millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm data, Very Large Array radio continuum data, and Heinrich Hertz Telescope dense gas (HCO+ and N2H+) spectroscopic data. We combine literature studies of star formation tracers and dust temperatures within IRDCs with our search for ultracompact (UC) H II regions to discuss a possible evolutionary sequence for IRDC clumps. In addition, we perform an analysis of mass tracers in IRDCs and find that 8 μm extinction masses and 1.1 mm BGPS masses are complementary mass tracers in IRDCs except for the most active clumps (notably those containing UC H II regions), for which both mass tracers suffer biases. We find that the measured virial masses in IRDC clumps are uniformly higher than the measured dust continuum masses on the scale of ~1 pc. We use 13CO, HCO+, and N2H+ to study the molecular gas properties of IRDCs and do not see any evidence of chemical differentiation between hot and cold clumps on the scale of ~1 pc. However, both HCO+ and N2H+ are brighter in active clumps, due to an increase in temperature and/or density. We report the identification of four UC H II regions embedded within IRDC clumps and find that UC H II regions are associated with bright (gsim1 Jy) 24 μm point sources, and that the brightest UC H II regions are associated with "diffuse red clumps" (an extended enhancement at 8 μm). The broad stages of the discussed evolutionary sequence (from a quiescent clump to an embedded H II region) are supported by literature dust temperature estimates; however, no sequential nature can be inferred between the individual star formation tracers.

  4. Treatment of tattoos with a picosecond alexandrite laser: a prospective trial.

    PubMed

    Saedi, Nazanin; Metelitsa, Andrei; Petrell, Kathleen; Arndt, Kenneth A; Dover, Jeffrey S

    2012-12-01

    OBJECTIVE To study a picosecond 755-nm alexandrite laser for the removal of tattoos to confirm the efficacy of this therapy, focusing on the effect of therapy on the target lesion as well as the surrounding tissues and quantifying the number of necessary treatments. DESIGN Fifteen patients with tattoos were enrolled. Treatments were scheduled approximately 6 ± 2 weeks apart. Standard photographs using 2-dimensional imaging were taken at baseline, before each treatment, and 1 month and 3 months after the last treatment. SETTING Dermatology clinic at SkinCare Physicians in Chestnut Hill, Massachusetts. PATIENTS Fifteen patients with darkly pigmented tattoos. MAIN OUTCOME MEASURES Treatment efficacy was assessed by the level of tattoo clearance in standard photographs. These photographs were assessed by a blinded physician evaluator and based on a 4-point scale. Efficacy was also assessed based on physician and patient satisfaction measured on a 4-point scale. RESULTS Twelve of 15 patients with tattoos (80%) completed the study. All 12 patients obtained greater than 75% clearance. Nine patients (75%) obtained greater than 75% clearance after having 2 to 4 treatments. The average number of treatment sessions needed to obtain this level of clearance was 4.25. All 12 patients (100%) were satisfied or extremely satisfied with the treatment. Adverse effects included pain, swelling, and blistering. Pain resolved immediately after therapy, while the swelling and blistering resolved within 1 week. Hypopigmentation and hyperpigmentation were reported at the 3-month follow-up. CONCLUSION The picosecond 755-nm alexandrite laser is a safe and very effective procedure for removing tattoo pigment.

  5. Treatment of tattoos with a picosecond alexandrite laser: a prospective trial.

    PubMed

    Saedi, Nazanin; Metelitsa, Andrei; Petrell, Kathleen; Arndt, Kenneth A; Dover, Jeffrey S

    2012-12-01

    OBJECTIVE To study a picosecond 755-nm alexandrite laser for the removal of tattoos to confirm the efficacy of this therapy, focusing on the effect of therapy on the target lesion as well as the surrounding tissues and quantifying the number of necessary treatments. DESIGN Fifteen patients with tattoos were enrolled. Treatments were scheduled approximately 6 ± 2 weeks apart. Standard photographs using 2-dimensional imaging were taken at baseline, before each treatment, and 1 month and 3 months after the last treatment. SETTING Dermatology clinic at SkinCare Physicians in Chestnut Hill, Massachusetts. PATIENTS Fifteen patients with darkly pigmented tattoos. MAIN OUTCOME MEASURES Treatment efficacy was assessed by the level of tattoo clearance in standard photographs. These photographs were assessed by a blinded physician evaluator and based on a 4-point scale. Efficacy was also assessed based on physician and patient satisfaction measured on a 4-point scale. RESULTS Twelve of 15 patients with tattoos (80%) completed the study. All 12 patients obtained greater than 75% clearance. Nine patients (75%) obtained greater than 75% clearance after having 2 to 4 treatments. The average number of treatment sessions needed to obtain this level of clearance was 4.25. All 12 patients (100%) were satisfied or extremely satisfied with the treatment. Adverse effects included pain, swelling, and blistering. Pain resolved immediately after therapy, while the swelling and blistering resolved within 1 week. Hypopigmentation and hyperpigmentation were reported at the 3-month follow-up. CONCLUSION The picosecond 755-nm alexandrite laser is a safe and very effective procedure for removing tattoo pigment. PMID:22986470

  6. Decomposition of soil organic matter by ectomycorrhizal fungi studied by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Nicolás, César; Tunlid, Anders; Persson, Per

    2015-04-01

    Boreal forests accumulate a fifth of the global soil organic matter (SOM) pool and play an important role in the carbon cycling. Most trees in these boreal forests live in symbiosis with ectomycorrhizal fungi (EMF) that sheath the plant root tips. In the symbiotic relationship, EMF provide nutrients from the soil to plants such as nitrogen and phosphorous, and trees give carbon in return to the fungi. When foraging for these nutrients, EMF use different strategies to explore the soil matrix. Long-distance exploration types grow far into the soil surroundings of the roots, while short-medium distance exploration ones grow close to the root tips. Despite these morphological differences among EMF, there is still little evidence of their functional role in the SOM decomposition. In this study, two ectomycorrhizal fungi Paxillus involutus and Laccaria bicolor, which belong to long and medium-distance smooth exploration types respectively, were grown in axenic cultures on SOM extracted from forest litter. To trigger the fungal decomposing activity, the extracts were supplemented with glucose. Chemical analysis and infrared spectroscopy were used to analyze the organic matter and chemometric tools such as principal component analysis (PCA), two-dimensional (2D) correlation analysis and multivariate curve resolution-alternating least squares (MCR-ALS) analysis were applied to further understand the chemical changes in the SOM. The first principal component of PCA explained 77% of the total variability and separated the treatments based on two infrared spectral regions: polysaccharides (970-1,150 cm-1) and carbonyl region (1,620-1,800 cm-1). Moreover, the 2D correlation analysis showed that the polysaccharides region in both treatments was negatively correlated with the carbonyl region, suggesting the production of oxidized compounds such as ketones during the uptake of glucose. The 2D correlation analysis also revealed that the diminution of intensity in the

  7. Shelf life study of egg albumin in pasteurized and non-pasteurized eggs using visible-near infrared spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A twelve week shelf life study was conducted on the egg albumen from both pasteurized and non-pasteurized shell eggs using visible-near infrared spectroscopy. The goal of the study was to correlate the chemical changes detected in the spectra to the measurement of Haugh units (measure of interior eg...

  8. Interaction between beta-Purothionin and dimyristoylphosphatidylglycerol: a (31)P-NMR and infrared spectroscopic study.

    PubMed Central

    Richard, Julie-Andrée; Kelly, Isabelle; Marion, Didier; Pézolet, Michel; Auger, Michèle

    2002-01-01

    The interaction of beta-purothionin, a small basic and antimicrobial protein from the endosperm of wheat seeds, with multilamellar vesicles of dimyristoylphosphatidylglycerol (DMPG) was investigated by (31)P solid-state NMR and infrared spectroscopy. NMR was used to study the organization and dynamics of DMPG in the absence and presence of beta-purothionin. The results indicate that beta-purothionin does not induce the formation of nonlamellar phases in DMPG. Two-dimensional exchange spectroscopy shows that beta-purothionin decreases the lateral diffusion of DMPG in the fluid phase. Infrared spectroscopy was used to investigate the perturbations, induced by beta-purothionin, of the polar and nonpolar regions of the phospholipid bilayers. At low concentration of beta-purothionin, the temperature of the gel-to-fluid phase transition of DMPG increases from 24 degrees C to ~33 degrees C, in agreement with the formation of electrostatic interactions between the cationic protein and the anionic phospholipid. At higher protein concentration, the lipid transition is slightly shifted toward lower temperature and a second transition is observed below 20 degrees C, suggesting an insertion of the protein in the hydrophobic core of the lipid bilayer. The results also suggest that the presence of beta-purothionin significantly modifies the lipid packing at the surface of the bilayer to increase the accessibility of water molecules in the interfacial region. Finally, orientation measurements indicate that the alpha-helices and the beta-sheet of beta-purothionin have tilt angles of ~60 degrees and 30 degrees, respectively, relative to the normal of the ATR crystal. PMID:12324425

  9. Study of Fourier transform infrared spectra of cockroach nervous tissue and chitin

    NASA Astrophysics Data System (ADS)

    Ghadage, Vijay H.; Kulkarni, Gauri R.; Bhoraskar, Sudha V.

    2012-03-01

    Fourier Transform Infrared Spectroscopy (FTIR) is a very sensitive tool which is capable of providing strong insight on structural and functional changes in lipids and proteins induced by laser radiation. In the present work cockroach nervous tissue and chitin from tibia region are irradiated with Nd: YAG laser (λ= 1064 nm, Power =150mW) via fiber optics (Numerical aperture=0.22, diameter = 8 μ). Nd: YAG laser exposure time is varied from 10 sec to 50 sec for nervous tissue and chitin. FTIR (Fourier Transform Infra Red spectra) of cockroach nervous tissue and chitin are compared before and after laser irradiation. The FTIR spectrum of non irradiated cockroach nervous tissue shows clearly the peaks due to O-H (Carboxylic acid), C=O (Amide I), C=C (Aromatic), N=0 (Nitro), C-H (Alkenes), CH (Aromatics). FTIR Spectra of non irradiated cockroach chitin clearly shows O-H (Carboxylic acid), C=O (Carbonyl stretch), C=C (Aromatic), N=O (Nitro), C-O, (anhydrides), C-H (Alkenes stretch) group. FTIR spectra of laser radiated nervous tissue from cockroach tibia and chitin shows significant changes in transmittance for O-H, C=O, C=C, C-H, N=O, C-O and C-H groups. The percentage transmittance increases for O-H, C=C group for exposure time 10sec, 40sec and 50 sec for nervous tissue. The percentage transmittance increases for O-H, C=C group for exposure time 10sec, 20sec, 30sec and 40 sec for chitin. The study shows clearly that FTIR spectroscopy of nervous tissue can reveal the interactions between infrared laser light and nervous tissue.

  10. Matrix isolation infrared spectroscopic study of the vapor species over heated ReO{sub 3}

    SciTech Connect

    Almond, M.J.; Orrin, R.H.; Ogden, J.S.

    1996-02-01

    The vapor phase species over ReO{sub 3} heated in vacuo to approx 400C have been trapped in argon or nitrogen matrices at approx 12 K. The only species within such matrices detected by infrared spectroscopy is Re{sub 2}O{sub 7}. The bands of matrix-isolated Re{sub 2}O{sub 7} have been assigned by comparison with the spectrum of the gaseous compound. Most of the isolated Re{sub 2}O{sub 7} is shown to be in the monomeric form; thus, an infrared absorption at 916.5 cm{sup {minus}1} (N{sub 2} matrix), which had previously been assigned to an aggregate of Re{sub 2}O{sub 7} may, on the basis of annealing experiments, be attributed to the monomer. The solid remaining in the sample tube following heating of the ReO{sub 3} sample consists of ReO{sub 2} in both the monoclinic and orthorhombic crystal forms alongside some unreacted cubic ReO{sub 3} and a small amount of orthorhombic Re{sub 2}O{sub 7}. Thus, it is found that thermal decomposition of ReO{sub 3} in vacuo at 400 C follows the expected disproportionation route. The authors find no spectroscopic evidence for the existence of other species, such as ReO{sub 3} or HReO{sub 4}, in the vapor above heated ReO{sub 3}. This finding is in contrast to the results of earlier mass spectrometric studies that suggested that molecular ReO{sub 3} was present in the vapor together with Re{sub 2}O{sub 7}.

  11. Infrared thermography based magnetic hyperthermia study in Fe3O4 based magnetic fluids

    NASA Astrophysics Data System (ADS)

    Lahiri, B. B.; Ranoo, Surojit; Philip, John

    2016-09-01

    Owing to the immense clinical benefits, magnetic hyperthermia is likely to emerge as an alternate cancer therapeutic procedure in the near future. Presently, radio frequency immune fiber optic based sensors are being used to monitor temperature changes during magnetic hyperthermia measurements, which have inherent limitations due to the requirement of physical contact of the sensor with the sample, contamination and temperature monitoring at a single point. Here, we investigate the field induced heating of oil based oleic acid coated Fe3O4 nanofluid, synthesized using co-precipitation method, using infrared thermal imaging (IRT) camera and compare the results with those of fiber optic temperature sensor. Experiments were performed on nanofluid samples of four different concentrations and under five different external field amplitudes. The specific absorption rate (SAR) of the samples were determined from the initial rate of temperature rise measured using both the techniques. The SAR values determined from both the techniques were in very good agreement with each other, with in an accuracy of 5%, after incorporating convection loss correction on the infrared thermal imaging data. The consecutive thermal cycling on the samples showed good thermal stability and thermal recovery. The maximum SAR obtained was 95.9 W/gFe for a sample concentration and field amplitude of 23 wt.% and 57.3 kA m-1, respectively. This study showed the efficacy and accuracy of temperature measurement using IRT during field induced heating of magnetic nanofluid and its advantages over conventional point measurements techniques for real-time, non-contact and wide area temperature mapping without sample contamination.

  12. Study on 512×128 pixels InGaAs near infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Li, Xue; Tang, Hengjing; Huang, Songlei; Shao, Xiumei; Li, Tao; Huang, Zhangcheng; Gong, Haimei

    2014-10-01

    It is well known that In0.53Ga0.47As epitaxial material is lattice-matched to InP substrate corresponding to the wavelength from 0.9μm to 1.7μm, which results to high quality material and good device characteristics at room temperature. In order to develop the near infrared multi-spectral imaging, 512×128 pixels InGaAs Near Infrared Focal Plane Arrays (FPAs) were studied. The n-InP/i-InGaAs/n-InP double hereto-structure epitaxial material was grown by MBE. The 512×128 back-illuminated planar InGaAs detector arrays were fabricated, including the improvement of passivation film, by grooving the diffusion masking layer, the P type electrode layer, In bump condition and so on. The photo-sensitive region has the diffusion area of 23×23μm2 and pixel pitch of 30×30μm2 . The 512×128 detector arrays were individually hybridized on readout integrated circuit(ROIC) by Indium bump based on flip-chip process to make focal plane arrays (FPAs). The ROIC is based on a capacitive trans-impedance amplifier with correlated double sampling and integrated while readout (IWR) mode with high readout velocity of every pixel resulting in low readout noise and high frame frequency. The average peak detectivity and the response non-uniformity of the FPAs are 1.63×1012 cmHz1/2/W and 5.9%, respectively. The power dissipation and frame frequency of the FPAs are about 180mW and 400Hz, respectively.

  13. Advantages of Picosecond Laser Machining for Cutting-Edge Technologies

    NASA Astrophysics Data System (ADS)

    Moorhouse, C.

    The demand to reduce the size, weight and material cost of modern electronic devices results in a requirement for precision micromachining to aid product development. Examples include making smaller and more powerful smartphones with brighter displays, eliminating the requirement for post-process cleaning and machining the latest bio- absorbable medical stents. The pace of innovation in high-tech industries has led to ultrafast (picosecond) industrial lasers becoming an important tool for many applications and the high repetition rates now available help to meet industrial throughput levels. This is due to the unique operating regime (megawatts of peak power) enabling clean cutting and patterning of sensitive materials and thin films used in a number of novel devices and allows micromachining of wide bandgap, "difficult" materials such as glass.

  14. Picosecond laser-induced water condensation in a cloud chamber.

    PubMed

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-01

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient.

  15. Picosecond ir hole-burning spectroscopy on HDO ice Ih

    NASA Astrophysics Data System (ADS)

    Seifert, G.; Weidlich, K.; Graener, H.

    1997-12-01

    Transient hole-burning experiments using picosecond ir pulses in the region of the OH stretching vibration of crystalline HDO (in D2O) ice are reported; holes with a minimum width of 26 cm-1 are measured, proving the OH band to be inhomogeneously broadened. The inhomogeneous distribution having a half width of approximately 25 cm-1 can be related to structural disorder in ice. A vibrational lifetime of 0.5 ps<=T1<=2 ps is found for the OH stretching mode. Additional features in the transient data are attributed to the dissipation of excess energy; particularly microscopic energy flow in the immediate surroundings of primarily excited OH groups can be monitored.

  16. Thermodynamic properties of liquid gallium from picosecond acoustic velocity measurements.

    PubMed

    Ayrinhac, S; Gauthier, M; Le Marchand, G; Morand, M; Bergame, F; Decremps, F

    2015-07-15

    Due to discrepancies in the literature data the thermodynamic properties of liquid gallium are still in debate. Accurate measurements of adiabatic sound velocities as a function of pressure and temperature have been obtained by the combination of laser picosecond acoustics and surface imaging on sample loaded in diamond anvil cell. From these results the thermodynamic parameters of gallium have been extracted by a numerical procedure up to 10 GPa and 570 K. It is demonstrated that a Murnaghan equation of state accounts well for the whole data set since the isothermal bulk modulus BT has been shown to vary linearly with pressure in the whole temperature range. No evidence for a previously reported liquid-liquid transition has been found in the whole pressure and temperature range explored.

  17. Picosecond laser-induced water condensation in a cloud chamber.

    PubMed

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-01

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient. PMID:27607654

  18. Mechanical characterization of temperature-sensitive objects using picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Dehoux, T.; Audoin, B.; Zouani, O.; Durrieu, M. C.

    2011-01-01

    Biological objects are exquisitely sensitive to temperature variations and their mechanical characterization is often a challenge when using the picosecond ultrasonics technique. To reduce the laser-induced temperature rise, we place single biological cells on a thin metal transducer and we focus the laser beam that generates the acoustic waves at frequencies <= 150 GHz on the rear side of the transducer. The acoustic waves propagate through the transducer and are partially transmitted to the cell to create the so-called Brillouin oscillations. The frequency of these oscillations provides a direct measurement of the sound velocity. The simultaneous measurement of the acoustic reflection coefficient at the transducer/cell interface allows the determination of both the density and the compressibility of the cell.

  19. Synchronization of Sub-Picosecond Electron and Laser Pulses

    SciTech Connect

    Rosenzweig, J.B.; Le Sage G.P.

    2000-08-15

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is subpicosecond, with tens of femtosecond synchronization implied for next-generation experiments. Typically, an RF electron accelerator is synchronized to a short pulse laser system by detecting the repetition signal of a laser oscillator, adjusted to an exact subharmonic of the linac RF frequency, and multiplying or phase locking this signal to produce the master RF clock. Pulse-to-pulse jitter characteristic of self-mode-locked laser oscillators represents a direct contribution to the ultimate timing jitter between a high intensity laser focus and electron beam at the interaction point, or a photocathode drive laser in an RF photoinjector. This timing jitter problem has been addressed most seriously in the context of the RF photoinjector, where the electron beam properties are sensitive functions of relative timing jitter. The timing jitter achieved in synchronized photocathode drive laser systems is near, or slightly below one picosecond. The ultimate time of arrival jitter of the beam at the photoinjector exit is typically a bit smaller than the photocathode drive-laser jitter due to velocity compression effects in the first RF cell of the gun. This tendency of the timing of the electron beam arrival at a given spatial point to lock to the RF lock is strongly reinforced by use of magnetic compression.

  20. Functional near-infrared spectroscopy: a continuous wave type based system for human frontal lobe studies

    PubMed Central

    Venclove, Sigita; Daktariunas, Algis; Ruksenas, Osvaldas

    2015-01-01

    Functional Near-Infrared Spectroscopy (fNIRS) is an optical non-invasive brain monitoring technology that registers changes in hemodynamic responses within the cortex of the human brain. Over the last decades fNIRS became a promising method in neurosciences: it is non-invasive, portable and can be used in long term studies. All these advantages make it suitable for educational purposes as well. This paper presents basic methodological concept of optical engineering principles and suitable applications of fNIRS. We represent a continuous wave (cw-fNIRS) system that could be used for frontal lobe studies in human adults or as demonstration equipment for physiological measurements. This system has been validated by comparing it with commercial device fNIR400 from Biopac. A comparison of geometry, data and statistical analyses suggests similar hemodynamic responses recorded by both devices. Our study suggests that this system can be used for further development and as a guideline for researchers to develop a specific tool for applications in human brain studies. PMID:26869869

  1. High average power difference-frequency generation of picosecond mid-IR pulses at 80MHz using an Yb-fiber laser pumped optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Michel, Julia; Beutler, Marcus; Rimke, Ingo; Büttner, Edlef; Farinello, Paolo; Agnesi, Antonio; Petrov, Valentin P.

    2015-02-01

    We present an efficient coherent source widely tunable in the mid-infrared spectral range consisting of a commercial picosecond Yb-fiber laser operating at 80 MHz repetition rate, a synchronously-pumped OPO (SPOPO) and differencefrequency generation (DFG) in AgGaSe2. With an average input pump power of 7.8 W at 1032 nm and at 80 MHz, the SPOPO outputs are tunable from 1380 to 1980 nm (Signal) and from 2.1 to ~4 μm (Idler) with pulse durations between 2.1 and 2.6 ps over the entire tuning range. After temporally overlapping Signal and Idler through a delay line, the two beams are spatially recombined with a dichroic mirror (reflecting for the Signal in s-polarization and transmitting for the Idler in p-polarization), and focused by a 150 mm CaF2 lens to a common focus. For DFG we employ an AR-coated 10- mm thick AgGaSe2 nonlinear crystal cut for type-I interaction at θ =52°. The generated mid-infrared picosecond pulses are continuously tunable between 5 and 18 μm with average power up to 130 mW at 6 μm and more than 1 mW at 18 μm. Their spectra and autocorrelation traces are measured up to 15 μm and 11 μm, respectively, and indicate that the input spectral bandwidth and pulse duration are maintained to a great extent in the nonlinear frequency conversion processes. The pulse duration slightly decreases from 2.1 to 1.9 ps at 6.7 μm while the spectral bandwidth supports ~1.5 ps (~10 cm-1)durations across the entire mid-infrared tuning range. For the first time narrow-band mid-infrared pulses with energy exceeding 1 nJ are generated at such high repetition rates.

  2. A SPITZER/INFRARED SPECTROGRAPH SPECTRAL STUDY OF A SAMPLE OF GALACTIC CARBON-RICH PROTO-PLANETARY NEBULAE

    SciTech Connect

    Zhang Yong; Kwok Sun; Hrivnak, Bruce J. E-mail: sunkwok@hku.h

    2010-12-10

    Recent infrared spectroscopic observations have shown that proto-planetary nebulae (PPNs) are sites of active synthesis of organic compounds in the late stages of stellar evolution. This paper presents a study of Spitzer/Infrared Spectrograph spectra for a sample of carbon-rich PPNs, all except one of which show the unidentified 21 {mu}m emission feature. The strengths of the aromatic infrared band, 21 {mu}m, and 30 {mu}m features are obtained by decomposition of the spectra. The observed variations in the strengths and peak wavelengths of the features support the model that the newly synthesized organic compounds gradually change from aliphatic to aromatic characteristics as stars evolve from PPNs to planetary nebulae.

  3. Pulsed picosecond 766 nm laser source operating between 1-80 MHz with automatic pump power management

    NASA Astrophysics Data System (ADS)

    Schönau, Thomas; Siebert, Torsten; Härtel, Romano; Eckhardt, Thomas; Klemme, Dietmar; Lauritsen, Kristian; Erdmann, Rainer

    2013-03-01

    The optical amplification and frequency conversion of a gain-switched 1532 nm distributed feedback (DFB) laser diode over a wide range of repetition rates are studied. A two stage Erbium fiber amplifier setup is pumped at 976 nm and operated at 1 to 80MHz pulse repetition frequency. The seed laser repetition rate is evaluated directly inside the pumping electronics to set the optimum pump power. Second-harmonic generation to 766 nm is achieved in a periodically poled lithium niobate bulk crystal. There is a high demand of several hundred milliwatt of picosecond pulsed laser power for stimulated emission depletion (STED) microscopy.

  4. Picosecond transient circular dichroism of the photoreceptor protein of the light-adapted form of Blepharisma japonicum

    NASA Astrophysics Data System (ADS)

    Hache, François; Khuc, Mai-Thu; Brazard, Johanna; Plaza, Pascal; Martin, Monique M.; Checcucci, Giovanni; Lenci, Francesco

    2009-11-01

    We present a picosecond transient circular dichroism study of OBIP, the putative photoreceptor protein involved in the photophobic response of Blepharisma japonicum. The probe wavelength was chosen at 230 nm. The results are compared to those of the isolated chromophore, OxyBP, in solution. The CD changes in OBIP and OxyBP do not show the same dynamics: OBIP's signal relaxes in a few ps whereas no such decay is obtained for OxyBP. This observation brings support to the formerly evoked existence of a fast photoinduced reaction in the chromoprotein, and demonstrates the implication of local geometrical changes that accompany this process.

  5. Photoinduced electron transfer and back transfer in systems of randomly distributed donors and acceptors: picosecond transient grating experiments

    SciTech Connect

    Dorfman, R.C.; Lin, Y.; Zimmt, M.B.; Baumann, J.; Domingue, R.P.; Fayer, M.D.

    1988-07-28

    Electron transfer from an optically excited donor (rubrene) to randomly distributed acceptors (duroquinone) followed by electron back transfer in a rigid solution (sucrose octaacetate) has been studied theoretically and experimentally. The forward electron transfer process was observed by time-dependent fluorescence quenching measurements, while the electron back transfer from the radical anion to the radical cation was monitored by using the picosecond transient grating (TG) technique. A statistical mechanics theory is used to describe the highly exponential TG signals and to extract the forward and back transfer parameters from the data. The agreement between the theory and experiments is excellent. The values of the forward and back transfer parameters are reported.

  6. Near Infrared Imaging As a Method of Studying Tsetse Fly (Diptera: Glossinidae) Pupal Development.

    PubMed

    Moran, Zelda R; Parker, Andrew G

    2016-01-01

    Near infrared (NIR) photography and video was investigated as a method for observing and recording intrapuparial development in the tsetse fly Glossina palpalis gambiensis and other Muscomorpha (Cyclorrhapha) Diptera. We showed that NIR light passes through the puparium, permitting images of the true pupae and pharate adult to be captured. Various wavelengths of NIR light from 880 to 1060 nm were compared to study the development of tsetse fly pupae from larviposition to emergence, using time-lapse videos and photographs. This study was carried out to advance our understanding of tsetse pupal development, specifically with the goal of improving a sorting technique which could separate male from female tsetse flies several days before emergence. Separation of the sexes at this stage is highly desirable for operational tsetse sterile insect technique control programmes, as it would permit the easy retention of females for the colony while allowing the males to be handled, irradiated and shipped in the pupal stage when they are less sensitive to vibration. In addition, it presents a new methodology for studying the pupal stage of many coarctate insects for many applications. NIR imaging permits observation of living pupae, allowing the entire development process to be observed without disruption. PMID:27402791

  7. Valence processing of first impressions in the dorsomedial prefrontal cortex: a near-infrared spectroscopy study.

    PubMed

    Yu, Chi-Lin; Wang, Min-Ying; Hu, Jon-Fan

    2016-05-25

    Previous studies have suggested that the dorsomedial prefrontal cortex (dmPFC) plays a central role in processing first impressions; however, little is known about how dmPFC processes different valences of first impressions. Moreover, it is still unclear as to whether the dmPFC shows lateralization or only induces different levels of activation when processing positive and negative impressions. To address these questions in the present study, the brain activities for the impression judgments expressed by participants were measured with near-infrared spectroscopy. For each real facial picture, participants were asked to evaluate their first impressions on a scale from 'bad' to 'good' using a keyboard. The results showed that although the right dmPFC has a higher sensitivity in processing impressions, both the hemispheres of dmPFC showed a significant trend where the activation of positive impressions was higher than the negative ones. Accordingly, it is proposed that the dmPFC acts as a single mechanism responsible for delineating the processing of first impressions rather than two lateralized systems. Therefore, a 'positivity dominance hypothesis' is also proposed, which states that dmPFC in both hemispheres have a higher sensitivity and priority for positive impressions than negative ones. The present study provides valuable findings with respect to the role of the dmPFC in the processes of first impression formation. PMID:27035730

  8. Study on memories of temporal lobes and the principles of lateralization using near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamakura, Katsutoshi

    2007-01-01

    In this study we measured the variation of brain blood quantity (Oxy-Hb, Deoxy-Hb and Total-Hb) in the temporal lobes using near infrared spectroscopy (NIRS) when the tasks of the memories were presented to the subjects. The memories are classified into the short-term memory (STM) and the long-term memory (LTM) including the episodic and semantic memories. The subjects joined in this study are 11 persons who are university students including graduate students. We used the language task of letter-number sequencing, also reverse sequencing to measure STM and the task of the episodic memory to measure LTM. As a result of analysis, concerning the episodic memory, the variation of Oxy-Hb in the left temporal lobe was larger than that of Oxy-Hb in the right temporal lobe. The result might suggest that the episodic memory has a relationship with cerebral dominance concerning language area in the left temporal lobe. It seems that the episodic memory meditated with the function of language used in this study is much stored in the left temporal lobe than in the right temporal lobe. This result coincides with the principles of lateralization. The variation of Oxy-Hb in the language task of letter-number sequencing was smaller than that of Oxy-Hb in the language task of the episodic memory.

  9. Wrist Hypothermia Related to Continuous Work with a Computer Mouse: A Digital Infrared Imaging Pilot Study.

    PubMed

    Reste, Jelena; Zvagule, Tija; Kurjane, Natalja; Martinsone, Zanna; Martinsone, Inese; Seile, Anita; Vanadzins, Ivars

    2015-08-07

    Computer work is characterized by sedentary static workload with low-intensity energy metabolism. The aim of our study was to evaluate the dynamics of skin surface temperature in the hand during prolonged computer mouse work under different ergonomic setups. Digital infrared imaging of the right forearm and wrist was performed during three hours of continuous computer work (measured at the start and every 15 minutes thereafter) in a laboratory with controlled ambient conditions. Four people participated in the study. Three different ergonomic computer mouse setups were tested on three different days (horizontal computer mouse without mouse pad; horizontal computer mouse with mouse pad and padded wrist support; vertical computer mouse without mouse pad). The study revealed a significantly strong negative correlation between the temperature of the dorsal surface of the wrist and time spent working with a computer mouse. Hand skin temperature decreased markedly after one hour of continuous computer mouse work. Vertical computer mouse work preserved more stable and higher temperatures of the wrist (>30 °C), while continuous use of a horizontal mouse for more than two hours caused an extremely low temperature (<28 °C) in distal parts of the hand. The preliminary observational findings indicate the significant effect of the duration and ergonomics of computer mouse work on the development of hand hypothermia.

  10. Skin temperature increase caused by a mobile phone: a methodological infrared camera study.

    PubMed

    Straume, Aksel; Oftedal, Gunnhild; Johnsson, Anders

    2005-09-01

    Mobile phone users often complain about burning sensations or a heating of the ear region. The increase in temperature may be due to thermal insulation by the phone, heating of the mobile phone resulting from its electrical power dissipation, and radio frequency (RF) exposure. The main objective of this study was to use infrared (IR) camera techniques to find how much each of these factors contributes to the increase in skin temperature resulting from the use of one GSM 900 phone. One subject, a healthy male, took part in the study. He was holding the phone in a normal position when the phone was switched off, when it was switched on but with the antenna replaced by a 50 Omega load to eliminate the RF exposure, and when it was transmitting RF fields. The output power could be fixed, and the minimal and the maximal power levels of the phone were used. The study was designed as a double blind experiment. The changes in temperature after 15 and 30 min of mobile phone use were calculated on the exposed side of the head relative to the unexposed side. The insulation and the electrical power dissipation led to statistically significant rises in the skin temperature, while the RF exposure did not.

  11. Wrist Hypothermia Related to Continuous Work with a Computer Mouse: A Digital Infrared Imaging Pilot Study

    PubMed Central

    Reste, Jelena; Zvagule, Tija; Kurjane, Natalja; Martinsone, Zanna; Martinsone, Inese; Seile, Anita; Vanadzins, Ivars

    2015-01-01

    Computer work is characterized by sedentary static workload with low-intensity energy metabolism. The aim of our study was to evaluate the dynamics of skin surface temperature in the hand during prolonged computer mouse work under different ergonomic setups. Digital infrared imaging of the right forearm and wrist was performed during three hours of continuous computer work (measured at the start and every 15 minutes thereafter) in a laboratory with controlled ambient conditions. Four people participated in the study. Three different ergonomic computer mouse setups were tested on three different days (horizontal computer mouse without mouse pad; horizontal computer mouse with mouse pad and padded wrist support; vertical computer mouse without mouse pad). The study revealed a significantly strong negative correlation between the temperature of the dorsal surface of the wrist and time spent working with a computer mouse. Hand skin temperature decreased markedly after one hour of continuous computer mouse work. Vertical computer mouse work preserved more stable and higher temperatures of the wrist (>30 °C), while continuous use of a horizontal mouse for more than two hours caused an extremely low temperature (<28 °C) in distal parts of the hand. The preliminary observational findings indicate the significant effect of the duration and ergonomics of computer mouse work on the development of hand hypothermia. PMID:26262633

  12. Near Infrared Imaging As a Method of Studying Tsetse Fly (Diptera: Glossinidae) Pupal Development

    PubMed Central

    Moran, Zelda R.; Parker, Andrew G.

    2016-01-01

    Near infrared (NIR) photography and video was investigated as a method for observing and recording intrapuparial development in the tsetse fly Glossina palpalis gambiensis and other Muscomorpha (Cyclorrhapha) Diptera. We showed that NIR light passes through the puparium, permitting images of the true pupae and pharate adult to be captured. Various wavelengths of NIR light from 880 to 1060 nm were compared to study the development of tsetse fly pupae from larviposition to emergence, using time-lapse videos and photographs. This study was carried out to advance our understanding of tsetse pupal development, specifically with the goal of improving a sorting technique which could separate male from female tsetse flies several days before emergence. Separation of the sexes at this stage is highly desirable for operational tsetse sterile insect technique control programmes, as it would permit the easy retention of females for the colony while allowing the males to be handled, irradiated and shipped in the pupal stage when they are less sensitive to vibration. In addition, it presents a new methodology for studying the pupal stage of many coarctate insects for many applications. NIR imaging permits observation of living pupae, allowing the entire development process to be observed without disruption. PMID:27402791

  13. Valence processing of first impressions in the dorsomedial prefrontal cortex: a near-infrared spectroscopy study.

    PubMed

    Yu, Chi-Lin; Wang, Min-Ying; Hu, Jon-Fan

    2016-05-25

    Previous studies have suggested that the dorsomedial prefrontal cortex (dmPFC) plays a central role in processing first impressions; however, little is known about how dmPFC processes different valences of first impressions. Moreover, it is still unclear as to whether the dmPFC shows lateralization or only induces different levels of activation when processing positive and negative impressions. To address these questions in the present study, the brain activities for the impression judgments expressed by participants were measured with near-infrared spectroscopy. For each real facial picture, participants were asked to evaluate their first impressions on a scale from 'bad' to 'good' using a keyboard. The results showed that although the right dmPFC has a higher sensitivity in processing impressions, both the hemispheres of dmPFC showed a significant trend where the activation of positive impressions was higher than the negative ones. Accordingly, it is proposed that the dmPFC acts as a single mechanism responsible for delineating the processing of first impressions rather than two lateralized systems. Therefore, a 'positivity dominance hypothesis' is also proposed, which states that dmPFC in both hemispheres have a higher sensitivity and priority for positive impressions than negative ones. The present study provides valuable findings with respect to the role of the dmPFC in the processes of first impression formation.

  14. Serial time-encoded amplified microscopy (STEAM) based on a stabilized picosecond supercontinuum source.

    PubMed

    Zhang, Chi; Qiu, Yi; Zhu, Rui; Wong, Kenneth K Y; Tsia, Kevin K

    2011-08-15

    Temporal stability of the broadband source, such as supercontinuum (SC), is the key enabling factor for realizing high performance ultrafast serial time-encoded amplified microscopy (STEAM). Owing to that the long-pulse SC (picosecond to nanosecond) generation generally results in an ultrabroadband spectrum with significant pulse-to-pulse fluctuation, only the ultrashort-pulse (femtosecond) SC sources, which offer better temporal stability, have been employed in STEAM so far. Here we report a simple approach to achieve active control of picosecond SC stability and to help extend the applicability of SC in STEAM from the femtosecond to the picosecond or even nanosecond regimes. We experimentally demonstrate stable single-shot STEAM imaging at a frame rate of 4.9 MHz using the CW-triggered picosecond SC source. Such CW-stabilized SC can greatly reduce the shot-to-shot fluctuation, and thus improves the STEAM image quality significantly.

  15. Serial time-encoded amplified microscopy (STEAM) based on a stabilized picosecond supercontinuum source

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Qiu, Yi; Zhu, Rui; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2011-08-01

    Temporal stability of the broadband source, such as supercontinuum (SC), is the key enabling factor for realizing high performance ultrafast serial time-encoded amplified microscopy (STEAM). Owing to that the long-pulse SC (picosecond to nanosecond) generation generally results in an ultrabroadband spectrum with significant pulse-to-pulse fluctuation, only the ultrashort-pulse (femtosecond) SC sources, which offer better temporal stability, have been employed in STEAM so far. Here we report a simple approach to achieve active control of picosecond SC stability and to help extend the applicability of SC in STEAM from the femtosecond to the picosecond or even nanosecond regimes. We experimentally demonstrate stable single-shot STEAM imaging at a frame rate of 4.9 MHz using the CW-triggered picosecond SC source. Such CW-stabilized SC can greatly reduce the shot-to-shot fluctuation, and thus improves the STEAM image quality significantly.

  16. Ultrafast Optical Beam Deflection in a Planar Waveguide for High Dynamic Range Recording at Picosecond Resolution

    SciTech Connect

    Sarantos, C H; Heebner, J E

    2008-07-02

    We report the latest performance of an ultrafast, all-optical beam deflector based on a prism array imprinted in a planar waveguide. The deflector enables single-shot, high dynamic range optical recording with picosecond resolution.

  17. Picosecond laser spectroscopy of charge-separation in photosynthetic model systems

    NASA Astrophysics Data System (ADS)

    Schaafsma, T. J.; Hofstra, U.; Koehorst, R. B. M.; Sanders, G. M.; Vanderplas, H. C.

    Charge-separation in synthetic donor-pigment-acceptor (DPA) compounds and concentration dimers of porphyrins was investigated by fluorescence quenching, EPR-spectroscopy and picosecond optical absorption spectroscopy.

  18. Infrared and Raman spectroscopical studies of salicylic and salicylate derivatives in aqueous solution

    NASA Astrophysics Data System (ADS)

    Humbert, B.; Alnot, M.; Quilès, F.

    1998-03-01

    The assignment of vibrations of salicylic acid, salicylate monoanion and salicylate bianion in aqueous solution are discussed with the help of Raman spectroscopy, of attenuated total reflection infrared spectroscopy and of the computational density functional theory (DFT) approach.

  19. Measurement of single soybean seed attributes by near infrared technologies. A comparative study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four near infrared spectrophotometers, and their associated spectral collection methods, were tested and compared for measuring three soybean single seed attributes: weight (g), protein (%), and oil (%). Using partial least squares (PLS) and 4 preprocessing methods, the attribute which was significa...

  20. Mineralogical Composition of the Mexican Ordinary Chondrite Type Meteorite: A Raman, Infrared and XRD Study

    NASA Astrophysics Data System (ADS)

    Ostrooumov, M.

    2016-08-01

    The Raman microprobe (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of seven mexican meteorites: Aldama, Cosina, El Pozo, Escalon, Nuevo Mercurio,Pacula, Zapotitlan Salinas.

  1. Feasibility Study of Utilizing Existing Infrared Array Cameras for Daylight Star Tracking on NASA's Ultra Long Duration Balloon (ULDB) Missions

    NASA Technical Reports Server (NTRS)

    Tueller, Jack (Technical Monitor); Fazio, Giovanni G.; Tolls, Volker

    2004-01-01

    The purpose of this study was to investigate the feasibility of developing a daytime star tracker for ULDB flights using a commercially available off-the-shelf infrared array camera. This report describes the system used for ground-based tests, the observations, the test results, and gives recommendations for continued development.

  2. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    SciTech Connect

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary D.; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parameter dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.

  3. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    DOE PAGESBeta

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary D.; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parametermore » dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.« less

  4. Assessment study of infrared detector arrays for low-background astronomical research

    NASA Technical Reports Server (NTRS)

    Ando, K. J.

    1978-01-01

    The current state-of-the-art of infrared detector arrays employing charge coupled devices (CCD) or charge injection devices (CID) readout are assessed. The applicability, limitations and potentials of such arrays under the low-background astronomical observing conditions of interest for SIRFT (Shuttle Infrared Telescope Facility) are determined. The following are reviewed: (1) monolithic extrinsic arrays; (2) monolithic intrinsic arrays; (3) charge injection devices; and (4) hybrid arrays.

  5. AN INFRARED THROUGH RADIO STUDY OF THE PROPERTIES AND EVOLUTION OF IRDC CLUMPS

    SciTech Connect

    Battersby, Cara; Bally, John; Ginsburg, Adam; Glenn, Jason; Jackson, James M.; Shirley, Yancy L.; Schlingman, Wayne

    2010-09-20

    We examine the physical properties and evolutionary stages of a sample of 17 clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared, millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm data, Very Large Array radio continuum data, and Heinrich Hertz Telescope dense gas (HCO{sup +} and N{sub 2}H{sup +}) spectroscopic data. We combine literature studies of star formation tracers and dust temperatures within IRDCs with our search for ultracompact (UC) H II regions to discuss a possible evolutionary sequence for IRDC clumps. In addition, we perform an analysis of mass tracers in IRDCs and find that 8 {mu}m extinction masses and 1.1 mm BGPS masses are complementary mass tracers in IRDCs except for the most active clumps (notably those containing UC H II regions), for which both mass tracers suffer biases. We find that the measured virial masses in IRDC clumps are uniformly higher than the measured dust continuum masses on the scale of {approx}1 pc. We use {sup 13}CO, HCO{sup +}, and N{sub 2}H{sup +} to study the molecular gas properties of IRDCs and do not see any evidence of chemical differentiation between hot and cold clumps on the scale of {approx}1 pc. However, both HCO{sup +} and N{sub 2}H{sup +} are brighter in active clumps, due to an increase in temperature and/or density. We report the identification of four UC H II regions embedded within IRDC clumps and find that UC H II regions are associated with bright ({approx}>1 Jy) 24 {mu}m point sources, and that the brightest UC H II regions are associated with 'diffuse red clumps' (an extended enhancement at 8 {mu}m). The broad stages of the discussed evolutionary sequence (from a quiescent clump to an embedded H II region) are supported by literature dust temperature estimates; however, no sequential nature can be inferred between the individual star formation tracers.

  6. A review of performance of near-infrared fluorescence imaging devices used in clinical studies

    PubMed Central

    Zhu, B

    2015-01-01

    Near-infrared fluorescence (NIRF) molecular imaging holds great promise as a new “point-of-care” medical imaging modality that can potentially provide the sensitivity of nuclear medicine techniques, but without the radioactivity that can otherwise place limitations of usage. Recently, NIRF imaging devices of a variety of designs have emerged in the market and in investigational clinical studies using indocyanine green (ICG) as a non-targeting NIRF contrast agent to demark the blood and lymphatic vasculatures both non-invasively and intraoperatively. Approved in the USA since 1956 for intravenous administration, ICG has been more recently used off label in intradermal or subcutaneous administrations for fluorescence imaging of the lymphatic vasculature and lymph nodes. Herein, we summarize the devices of a variety of designs, summarize their performance in lymphatic imaging in a tabular format and comment on necessary efforts to develop standards for device performance to compare and use these emerging devices in future, NIRF molecular imaging studies. PMID:25410320

  7. The background-limited infrared-submillimeter spectrograph (BLISS) for SPICA: a design study

    NASA Astrophysics Data System (ADS)

    Bradford, C. M.; Bock, James; Holmes, Warren; Kenyon, M.; Beyer, A.; Werner, M.; Rud, M.; Prouvé, T.; Echternach, P.; Irwin, K.; Cho, S.; Harwit, M.; Stacey, G.; Helou, G.; Armus, L.; Appleton, P.; Smith, J. D.; Gorti, U.; Rieke, G.; Egami, E.; Lester, D.; Glenn, J.; Malkan, M.; Dale, D.

    2010-07-01

    We are developing the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) for SPICA to provide a breakthrough capability for far-IR survey spectroscopy. SPICAs large cold aperture allows mid-IR to submm observations which are limited only by the natural backgrounds, and BLISS is designed to operate near this fundamental limit. BLISS-SPICA is 6 orders of magnitude faster than the spectrometers on Herschel and SOFIA in obtaining full-band spectra. It enables spectroscopy of dust-obscured galaxies at all epochs back to the rst billion years after the Big Bang (redshift 6), and study of all stages of planet formation in circumstellar disks. BLISS covers 35 - 433 microns range in ve or six wavelength bands, and couples two 2 sky positions simultaneously. The instrument is cooled to 50 mK for optimal sensitivity with an on-board refrigerators. The detector package is 4224 silicon-nitride micro-mesh leg-isolated bolometers with superconducting transition-edge-sensed (TES) thermistors, read out with a cryogenic time-domain multiplexer. All technical elements of BLISS have heritage in mature scientic instruments, and many have own. We report on our design study in which we are optimizing performance while accommodating SPICAs constraints, including the stringent cryogenic mass budget. In particular, we present our progress in the optical design and waveguide spectrometer prototyping. A companion paper in Conference 7741 (Beyer et al.) discusses in greater detail the progress in the BLISS TES bolometer development.

  8. A functional near-infrared spectroscopy study of sustained attention to local and global target features.

    PubMed

    De Joux, Neil; Russell, Paul N; Helton, William S

    2013-04-01

    Despite a long history of vigilance research, the role of global and local feature discrimination in vigilance tasks has been relatively neglected. In this experiment participants performed a sustained attention task requiring either global or local shape stimuli discrimination. Reaction time to local feature discriminations was characterized by a quadratic trend over time-on-task with performance levels returning to initial levels late in the task. This trend did not occur in the global shape discrimination task. Functional near-infrared spectroscopy (fNIRS) was utilized in this study as an index of cerebral activation. In both tasks there was increased right hemisphere relative to left hemisphere oxygenation and right hemisphere oxygenation increased with time-on-task. Left hemisphere oxygenation, however, decreased slightly in the global task, but increased significantly in the local task as task duration increased. Indeed, total oxygenation, averaging both right and left, increased more with time-on-task in the local discrimination task. Both the performance and physiological results of this study indicate increased utilization of bilateral cerebral resources with time-on-task in the local, but not the global discrimination vigil.

  9. Study of the hydrolysis of uranium hexafluoride by Fourier transform infrared spectroscopy

    SciTech Connect

    Anderson, S.P.

    1982-08-01

    The reaction of uranium hexafluoride with water has been studied by using Fourier transform infrared (FT-IR) spectroscopy. Several different methods for accomplishing this task have been carried out. In addition, interpretatins of the results have been made. These interpretations have been based on literature values for the reactants and for compounds analogous to possible products. It was shown that classical matrix-isolation techniques proved to be unsatisfactory for studying this reaction. Other methods were developed in order to obtain results. They were: (1) the codeposition of pure UF/sub 6/ and H/sub 2/O on a cold window at 16/sup 0/K, (2) the codeposition of argon matrix to sample ratios of 10:1 to 2:1 of UF/sub 6/ and H/sub 2/O at 16/sup 0/K, and (3) the annealing of the samples produced by (1) and (2) while they were being scanned with FT-IR. 78 refs., 86 figs., 7 tabs.

  10. An experimental study of noise in mid-infrared quantum cascade lasers of different designs

    NASA Astrophysics Data System (ADS)

    Schilt, Stéphane; Tombez, Lionel; Tardy, Camille; Bismuto, Alfredo; Blaser, Stéphane; Maulini, Richard; Terazzi, Romain; Rochat, Michel; Südmeyer, Thomas

    2015-04-01

    We present an experimental study of noise in mid-infrared quantum cascade lasers (QCLs) of different designs. By quantifying the high degree of correlation occurring between fluctuations of the optical frequency and voltage between the QCL terminals, we show that electrical noise is a powerful and simple mean to study noise in QCLs. Based on this outcome, we investigated the electrical noise in a large set of 22 QCLs emitting in the range of 7.6-8 μm and consisting of both ridge-waveguide and buried-heterostructure (BH) lasers with different geometrical designs and operation parameters. From a statistical data processing based on an analysis of variance, we assessed that ridge-waveguide lasers have a lower noise than BH lasers. Our physical interpretation is that additional current leakages or spare injection channels occur at the interface between the active region and the lateral insulator in the BH geometry, which induces some extra noise. In addition, Schottky-type contacts occurring at the interface between the n-doped regions and the lateral insulator, i.e., iron-doped InP, are also believed to be a potential source of additional noise in some BH lasers, as observed from the slight reduction in the integrated voltage noise observed at the laser threshold in several BH-QCLs.

  11. Fourier transform infrared analysis of Tamra Bhasma at different levels: A preliminary study

    PubMed Central

    Chaudhari, Swapnil Y.; Rajput, Dhirajsingh S.; Galib, R.; Prajapati, Pradeep Kumar

    2015-01-01

    Introduction: Tamra Bhasma, one among the herbo-metallic preparations is extensively used in Ayurveda for different conditions. To make it safe to use, Tamra has to pass through a set of classical pharmaceutical procedures including a series of quenching in prescribed liquids, followed by incineration with black sulfide of mercury and herbal juice of Citrus jambhiri Lush. and corm of Amorphophallus campanulatus Linn. FTIR profiles of Tamra Bhasma at different levels is not available. Aim: To evaluate the chemical changes in Tamra Bhasma at different steps by following Fourier transform infrared (FTIR) spectroscopy. Materials and Methods: In current study, raw Tamra, intermediate samples obtained during purification, incineration and Amritikarana were analyzed using FTIR. Results: It was observed that Shodhana procedure leads in the formation of bonds between surface particles of Tamra and Shodhana media. These formed bonds on the surface of Shodhita Tamra samples gave various sharp peaks representing presence of many functional groups. Conclusion: The FTIR spectra revealed that both Bhasma samples contained organic compounds probably in the form of a complex with common functional groups like alkyl, methyl, etc., which need further studies for exact characterization of the complexes. PMID:26730144

  12. The structure of betaxolol studied by infrared spectroscopy and natural bond orbital theory

    NASA Astrophysics Data System (ADS)

    Canotilho, João; Castro, Ricardo A. E.

    2010-08-01

    Betaxolol is a selective β 1 receptor blocker used in the treatment of hypertension and glaucoma. A study of the betaxolol structure based on infrared spectroscopy and natural bond orbital (NBO) theory is the main aim of the present research. FTIR spectra of the solid betaxolol were recorded in the region from 4000 to 400 cm -1, in the temperature range between 25 and -170 °C. For spectral interpretation, spectrum of the deuterated betaxolol and the theoretical vibrational spectra of the conformer present in the solid obtained at the B3LYP/6-31G* level of theory, were used. Further insight into the structure was provided by natural bond orbital theory. NBO analysis of the conformer, before and after optimization, was carried out at the same level of theory referred above. Vibrational modes involved in hydrogen bond in the stretching and bending region were used in the estimation of the enthalpy using empirical correlations between enthalpy and the frequency shift that occurs as a result of the establishment of intermolecular hydrogen bonds. A detailed study of the structure of betaxolol and of its intermolecular interactions was obtained from the combination spectroscopy and NBO theory.

  13. Motor response investigation in individuals with cerebral palsy using near infrared spectroscopy: pilot study.

    PubMed

    Chaudhary, Ujwal; Hall, Michael; Gonzalez, Jean; Elbaum, Leonard; Bloyer, Martha; Godavarty, Anuradha

    2014-01-20

    Cerebral palsy (CP) describes a group of motor impairment syndromes secondary to genetic that may be due to acquired disorders of the developing brain. In this study, near infrared spectroscopy (NIRS) is used to investigate the prefrontal cortical activation and lateralization in response to the planning and execution of motor skills in controls and individuals with CP. The prefrontal cortex, which plays a dominant role in the planning and execution of motor skill stimulus, is noninvasively imaged using a continuous wave-based NIRS system. During the study, 7 controls (4 right-handed and 3 left-handed) and 2 individuals with CP (1 right-handed and 1 left-handed) over 18 years of age performed 30 s of a ball throwing task followed by 30 s rest in a 5-block paradigm. The optical signal acquired from the NIRS system was processed to elucidate the activation and lateralization in the prefrontal region of controls and individuals with CP. The preliminary result indicated a difference in activation between the task and rest conditions in all the participant types. Bilateral dominance was observed in the prefrontal cortex of controls in response to planning and execution of motor skill tasks, while an ipsilateral dominance was observed in individuals with CP. In conjunction, similar contralateral dominance was observed during rest periods, both in controls and individuals with CP.

  14. Structural effects of simvastatin on liver rate tissue: Fourier transform infrared and Raman microspectroscopic studies

    NASA Astrophysics Data System (ADS)

    Garip, Sebnem; Bayari, Sevgi Haman; Severcan, Mete; Abbas, Sherif; Lednev, Igor K.; Severcan, Feride

    2016-02-01

    Simvastatin is one of the most frequently prescribed statins because of its efficacy in the treatment of hypercholesterolemia, reducing cardiovascular risk and related mortality. Determination of its side effects on different tissues is mandatory to improve safe use of this drug. In the present study, the effects of simvastatin on molecular composition and structure of healthy rat livers were investigated by Fourier transform infrared and Raman imaging. Simvastatin-treated groups received 50 mg/kg/day simvastatin for 30 days. The ratio of the area and/or intensity of the bands assigned to lipids, proteins, and nucleic acids were calculated to get information about the drug-induced changes in tissues. Loss of unsaturation, accumulation of end products of lipid peroxidation, and alterations in lipid-to-protein ratio were observed in the treated group. Protein secondary structure studies revealed significant decrease in α-helix and increase in random coil, while native β-sheet decreases and aggregated β-sheet increases in treated group implying simvastatin-induced protein denaturation. Moreover, groups were successfully discriminated using principal component analysis. Consequently, high-dose simvastatin treatment induces hepatic lipid peroxidation and changes in molecular content and protein secondary structure, implying the risk of liver disorders in drug therapy.

  15. A comparative study of infrared and microwave heating for microbial decontamination of paprika powder

    PubMed Central

    Eliasson, Lovisa; Isaksson, Sven; Lövenklev, Maria; Ahrné, Lilia

    2015-01-01

    There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices’ sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms. PMID:26483783

  16. A System Trade Study of Remote Infrared Imaging for Space Shuttle Reentry

    NASA Technical Reports Server (NTRS)

    Schwartz, Richard J.; Ross, Martin N.; Baize, Rosemary; Horvath, Thomas J.; Berry, Scott A.; Krasa, Paul W.

    2008-01-01

    A trade study reviewing the primary operational parameters concerning the deployment of imaging assets in support of the Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) project was undertaken. The objective was to determine key variables and constraints for obtaining thermal images of the Space Shuttle orbiter during reentry. The trade study investigated the performance characteristics and operating environment of optical instrumentation that may be deployed during a HYTHIRM data collection mission, and specified contributions to the Point Spread Function. It also investigated the constraints that have to be considered in order to optimize deployment through the use of mission planning tools. These tools simulate the radiance modeling of the vehicle as well as the expected spatial resolution based on the Orbiter trajectory and placement of land based or airborne optical sensors for given Mach numbers. Lastly, this report focused on the tools and methodology that have to be in place for real-time mission planning in order to handle the myriad of variables such as trajectory ground track, weather, and instrumentation availability that may only be known in the hours prior to landing.

  17. Fourier transform infrared study of the effect of different cations on bacteriorhodopsin protein thermal stability.

    PubMed Central

    Heyes, Colin D; Wang, Jianping; Sanii, Laurie S; El-Sayed, Mostafa A

    2002-01-01

    The effect of divalent ion binding to deionized bacteriorhodopsin (dI-bR) on the thermal transitions of the protein secondary structure have been studied by using temperature-dependent Fourier transform infrared (FT-IR) spectroscopy. The native metal ions in bR, Ca(2+), and Mg(2+), which we studied previously, are compared with Mn(2+), Hg(2+), and a large, synthesized divalent organic cation, ((Et)(3)N)(2)Bu(2+). It was found that in all cases of ion regeneration, there is a pre-melting, reversible conformational transition in which the amide frequency shifts from 1665 to 1652 cm(-1). This always occurs at approximately 80 degrees C, independent of which cation is used for the regeneration. The irreversible thermal transition (melting), monitored by the appearance of the band at 1623 cm(-1), is found to occur at a lower temperature than that for the native bR but higher than that for acid blue bR in all cases. However, the temperature for this transition is dependent on the identity of the cation. Furthermore, it is shown that the mechanism of melting of the organic cation regenerated bR is different than for the metal cations, suggesting a difference in the type of binding to the protein (either to different sites or different binding to the same site). These results are used to propose specific direct binding mechanisms of the ions to the protein of deionized bR. PMID:11867472

  18. Rotational dynamics of confined C60 from near-infrared Raman studies under high pressure

    SciTech Connect

    Zou, Y.; Liu, B.; Wang, L.; Liu, D.; Yu, S.; Wang, P.; Wang, T.; Yao, M.; Li, Q.; Zou, B.; Cui, T.; Zou, G.; Wagberg, T.; Sundqvist, B.; Mao, H.-K.

    2009-12-29

    Peapods present a model system for studying the properties of dimensionally constrained crystal structures, whose dynamical properties are very important. We have recently studied the rotational dynamics of C60 molecules confined inside single walled carbon nanotube (SWNT) by analyzing the intermediate frequency mode lattice vibrations using near-infrared Raman spectroscopy. The rotation of C60 was tuned to a known state by applying high pressure, at which condition C60 first forms dimers at low pressure and then forms a single-chain, nonrotating, polymer structure at high pressure. In the latter state the molecules form chains with a 2-fold symmetry. We propose that the C60 molecules in SWNT exhibit an unusual type of ratcheted rotation due to the interaction between C60 and SWNT in the “hexagon orientation,” and the characteristic vibrations of ratcheted rotation becomes more obvious with decreasing temperature.

  19. Microstructural and Photoacoustic Infrared Spectroscopic Studies of Human Cortical Bone with Osteogenesis Imperfecta

    NASA Astrophysics Data System (ADS)

    Gu, Chunju; Katti, Dinesh R.; Katti, Kalpana S.

    2016-04-01

    The molecular basis of bone disease osteogenesis imperfecta (OI) and the mineralization of hydroxyapatite in OI bone have been of significant research interest. To further investigate the mechanism of OI disease and bone mineralization, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and x-ray diffraction (XRD) are used in the present study to describe the structural and compositional differences between OI and healthy bone. OI bone exhibits more porous, fibrous features, abnormal collagen fibrils, and abnormal mineral deposits. Likewise, photoacoustic-FTIR experiments indicate an aberrant collagen structure and an altered mineral structure in OI. In contrast, there is neither significant difference in the non-collagenous proteins (NCPs) composition observed nor apparent change in the crystal structure between OI and healthy bone minerals as shown in XRD and energy-dispersive x-ray spectroscopy (EDS) results. This observation indicates that the biomineralization process is more controlled by the bone cells and non-collagenous phosphorylated proteins. The present study also confirms that there is an orientational influence on the stoichiometry of the mineral in OI bone. Also, a larger volume of the hydrated layer in the transverse plane than the longitudinal plane of the mineral crystal structure is proposed. The appearance of a new C-S band in the FTIR spectra in OI bone suggests the substitution of glycine by cysteine in collagen molecules or/and an increased amount of cysteine-rich osteonectin that relates to mineral nucleation and mineral crystal formation.

  20. A comparative study of infrared and microwave heating for microbial decontamination of paprika powder.

    PubMed

    Eliasson, Lovisa; Isaksson, Sven; Lövenklev, Maria; Ahrné, Lilia

    2015-01-01

    There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices' sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.