... across the military departments and agencies for Research ... Title : Absorption Calorimetry and Laser Induced Damage Threshold Measurements on ...
DTIC Science & Technology
... Title : POSSIBILITY OF ABSORPTION OF SOLAR LYMAN ALPHA RADIATION BY THE INTERPLANETARY MEDIUM,. Descriptive ...
... Title : Characterization and Analysis of the CO(2) Laser-Induced Ablation of Lithium Target via Laser-Induced Fluorescence and Absorption ...
... AND SUBTITLE Laser Induced Asymmetry and Inhomegeneous Broadening of the ... tuned to either of the Doppler broadened hyperfine absorption ...
... Accession Number : ADD854771. Title : Laser-Induced Damage and Two-Photon Absorption Measurements in CdTe. Descriptive ...
... Accession Number : ADD255887. Title : Laser-Induced Damage and Two-Photon Absorption Measurements in CdTe. Descriptive ...
Mar 29, 2011 ... Thermal-Dissociation Laser Induced Fluorescence, TD-LIF, Ronald C. Cohen (PI) ... Harvard Lyman-� Photofragment Fluorescence Hygrometer ...
NASA Website
... MOLECULAR SPECTROSCOPY, LASER INDUCED FLUORESCENCE, MOLECULAR ... ABSORPTION, ATOMIC SPECTROSCOPY, DISSOCIATION ...
Laser-induced fluorescence and phosphorescence as well as infrared and visible absorption spectra of
NASA Technical Reports Server (NTRS)
in the near infrared wavelength range--review and measurements Laser-Induced Interstitial Thermotherapy ed G
E-print Network
... RESPONSE, SIGNALS, LEVEL(QUANTITY), PHOTONS, NERVOUS SYSTEM, EYE, ABSORPTION, PIGMENTS, FROGS, LASER DAMAGE ...
... been measured by monitoring the loss rate of hydrogen atoms in the presence of excess Cl2 and F2 via time-resolved, laser-induced Lyman-alpha ...
Nov 12, 2000 ... These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest. ...
Sep 6, 2011 ... An adjustable molecular hydrogen absorption cell provided temperature data on the incoming Lyman-alpha radiation, and a hydrogen-discharge ...
A two-photon absorption process was used to study resonance ionization spectroscopy of atoms, molecules in the gas phase, laser-induced fluorescence spectra in the condensed phase and laser induced chemical reactions in solutions. 8 refs., 1 fig., 1 tab.
Energy Citations Database
The continuous absorption spectra of small molecules have been examined using Laser Induced Photodissociation Spectroscopy (LIPS). In this technique, molecules are photolyzed using a flashlamp-pumped tunable dye laser; the atomic products of the dissociat...
National Technical Information Service (NTIS)
An analytical solution is presented for the reconstruction of spatially resolved species number densities from spatially resolved laser-induced fluorescence measurements when the integrated absorption of the laser light is known. The stability of the solu...
Laser-induced Lyman-(alpha) fluorescence of the hydrogen isotopes is investigated with regard to diagnostic applications in magnetically confined fusion plasmas. A formal analysis is presented for two excitation schemes: one-photon and Doppler-free two-ph...
This investigation covers the development of nonintrusive, laser-based optical diagnostic tools for the measurement of trace amount molecular species in hostile, reactive environments such as plasmas. Two- photon laser induced fluorescence (LIF) spectroscopy is applied to obtain the temperature of atomic hydrogen and Cavity Ring-Down Spectroscopy (CRDS) to ...
NASA Astrophysics Data System (ADS)
A method and apparatus are disclosed for measuring trace amounts of constituents in samples by using laser induced breakdown spectroscopy and laser induced fluorescence under ambient conditions. The laser induced fluorescence is performed at a selected wavelength ...
... SOLAR RADIATION), ABSORPTION ... SCATTERING, HYDROGEN, ALPHA PARTICLES ... PHOTOMETERS, MEASUREMENT, PHOTOMULTIPLIER ...
A separate hydrogen deuterium absorption cell measures the relative abundance of deuterium and hydrogen from their lyman-alpha emission. ...
... have devised for measuring the absolute H density involves absorption spectroscopy on the Lyman-alpha transition of ...
Sep 18, 2007 ... Remote chemical analysis via spectroscopy is an important tool in the ... Laser Induced Breakdown Spectroscopy, absorption spectroscopy and ...
CW lasers were applied to path-integrated absorption measurements of transient shock-tube flows and spatially resolved laser-induced fluorescence ...
... flash photolysis has been used to study triplet state absorption and fluorescence emission of monomers and dimers of acridine orange and other ...
... Descriptors : *Patent applications, *Laser beams, *Reaction kinetics, *Carbon dioxide lasers, Chemical reactions, Excitation, Angles, Absorption ...
... Absorption by reacted phenolphthalein provided cross-stream average product thickness and laser induced fluorescence intensity provided the ...
Arguments are presented that QSO Lyman-alpha absorption lines might arise in denser environments than is usually thought, with a larger neutral fraction in the gas than in the usual models of rarefied intergalactic clouds, and a much smaller total mean mass density in Lyman-alpha clouds. A model is sketched in which collapse or ...
Studying the Lyman-alpha forest allows us to trace the cosmological distribution of matter through time, and may reveal insights into important questions such as the onset of galaxy formation. An equation for determining the number of Lyman-alpha absorpti...
Cracks can affect laser damage susceptibility in three ways. These are field intensification due to interference, enhanced absorption due to trapped material in the cracks, and increased mechanical weakness. Enhanced absorption is the most important effect.
DOE Information Bridge
The rate constants for H atom reactions with Cl2 and F2 have been measured by monitoring the loss rate of hydrogen atoms in the presence of excess Cl2 and F2 via time-resolved, laser-induced Lyman-alpha fluorescence. The rate constants for H + F2 and H + ...
Eastern chilled mirror dewpoint hygrometer and a fast response Lyman Alpha absorption hygrometer as the radiosondes were launched intercomparisons between the aircraft lyman alpha hygrometer and the radiosonde and aircraft lyman alpha hygrometer for 22 co-located ascents. Figure 3. Figure 4. These comparisons show
Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorp...
Laser-induced motion is calculated for an underdense magnetically confined plasma column subjected to axial laser heating. Perturbation velocities and densities are determined for small values of the disturbance parameter defined as the ratio of the speed of sound to the speed of plasma growth due directly to laser absorption. The calculation ...
The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species has been applied to single-point measurements of velocity and static temperature in the NASA Ames Interaction Heating Facility (IHF) arc j...
Plasmas created by a Nd:yttrium aluminum garnet laser show systematic changes in local electron temperature when bathed by a continuous wave laser of increasing irradiance. By monitoring the local electron density, the laser light absorption coefficient, and the signal to noise ratio in neutral emissions, we explain the changes in electron temperature and signal to noise to be ...
A numerical iterative procedure is presented for the evaluation of the effect of signal absorption in two-color laser-induced incandescence measurements. The correction process is applied to our experimental data in an axisymmetric flame [Appl. Opt. 44, 7414 (2005)]. The influence of signal trapping on peak soot temperature and on soot volume fraction has ...
absorption by human tissue-like plastic, aiding in the de- velopment of protective technologies to ... planetary hydrogen emission, the Lyman Alpha line . ...
Accordling to the theory of big-bang nucleosynthesis (Yang ... the Lyman a absorption lines in high red-shift quasar spectra. These systems are ...
The interpretation that the nighttime Lyman alpha observed from rockets is solar Lyman alpha that was transported to the night side by the earth's extensive hydrogen envelope (the geocorona) is considered in detail. The equations of radiation transfer are solved for several spherically symmetric models of the hydrogen distribution. ...
Ion and neutral parameters are determined in the high electron density, magnetized, hydrogen plasma beam of an ITER divertor relevant plasma via measurements of the n=2 excited neutrals. Ion rotation velocity (up to 7 km/s) and temperature (2-3?eV~T_{e}) are obtained from analysis of H? spectra measured close to the plasma source. The methodology for neutral density determination is explained ...
PubMed
Ion and neutral parameters are determined in the high electron density, magnetized, hydrogen plasma beam of an ITER divertor relevant plasma via measurements of the n=2 excited neutrals. Ion rotation velocity (up to 7 km/s) and temperature (2�3eV~Te) are obtained from analysis of H? spectra measured close to the plasma source. The methodology for neutral density determination is explained ...
We study the characteristics of the ultraviolet continuum of the quasar PKS 0405-123 using the archival HST/FOS spectrum. The spectrum from 1150 to 3300 Angstroms shows a steeply rising continuum in F_? with a strong absorption feature ~ 100 Angstroms wide around the intrinsic Lyman limit of this z=0.574 quasar. The spectrum also shows ...
A review is presented of the current state of knowledge of laser energy absorption in gas engines, such as laser-powered rockets. Absorption for both continuous wave (CW) and pulsed engines are considered. For CW engines, absorption by laser-supported combustion (LSC) waves and by molecular resonance are possible mechanisms. For pulsed ...
Optical absorption and emission spectra provide information about the distribution of local atomic environments of rare earths in glass and how they change with glass composition and processing. Laser-induced fluorescence line-narrowed spectra provide add...
We present a new and unique way of forming an intense electric field near a molecule in order to induce electrochromism. We have done this by creating an electron-hole pair within close proximity to, but electronically isolated form, a polarizable molecul...
This book discusses the tools and concepts used by practitioners in the field of laser spectroscopy and provides reference material for further study. Resonance photoionization, laser absorption, laser-induced breakdown, photodissociation, Raman scattering, remote sensing, and laser-induced fluorescence are presented.
In this report, we conduct the initial theoretical investigation of emission of radiation by DNA components upon the absorption of infrared (IR) radiation. Excitation wavelengths in 9 and 11 urn region are of interest. These transitions are related to the...
The chemical aging of pentaerythritol tetranitrate (PETN) has been and continues to be an important problem in producing and maintaining high energy compounds and components. The work done to date has identified several key concerns in evaluating the chem...
In the nanosecond laser ablation regime, absorption of laser energy by the plasma during its early stage expansion critically influences the properties of the plasma and thus its interaction with ambient air. These influences can significantly alter spect...
The Lyman edge region in the spectra of 11 high-redshift quasars is studied using data designed to detect broadened Lyman edge absorption predicted by thermal models of the 'big blue bump' continuum component, especially thin accretion disks. Three objects have broadened, partial edges near the systemic redshifts, as ...
Theoretical Lyman ? absorption profiles show a significant dependence on temperature of the H2 satellite at 1600 �, whereas the H2+ satellite at 1400 � remains unchanged. The use of opacities calculated with different approximations concerning the electric dipole transition moment (constant, dependent on interatomic distance, and modulated by the ...
Excimer laser radiation changes the physical and optical properties of fused silica. These changes include laser induced absorption and density changes in the glass. Such effects may have an impact on the length of time for which optical elements made of fused silica can be used in DUV lithography systems. Corning Incorporated has ...
It has been conjectured that atomic oxygen and ozone can have a great influence on the plasma oxidation of ultrathin aluminum for magnetic tunnel junctions. In order to measure the density of O and ozone, two-photon absorption laser induced fluorescence measurements are performed in the dc glow plasma that is used for the oxidation ...
We have made progress in the areas related to the propulsion and confinement of gas responsible for broad absorption troughts in QSOs: Radiative Acceleration in BALQSOs; The 'Ghost' of Lyman (alpha); and Magnetic Confinement of Absorbing Gas.
Low reslution IUE spectra of SS Cygni obtained near quiescence show a strong absorption feature near 1225A. If this feature is interpreted as the red wing of the Lyman alpha absorption in the spectrum of the white dwarf component, then the star has an eff...
A multitude of absorption lines seen shortward of QSO Ly-alpha emission, that cannot be traced to heavy element absorption systems, are assumed to be Ly-alpha lines arising in intervening clouds. Studies of these Ly-alpha clouds, typically done at 1 A or ...
Absorption lines in the Ly(alpha) forest can be thought of as peaks in neutral hydrogen density along lines of sight. The column density distribution (the number density of absorption lines as a function of column density) is then a statistic of density p...
Direct absorption spectroscopy is used for the measurement of atmospheric OH; autocalibration is achieved by laser induced fluorescence. Measurements by optical absorption present problems concerning the selfproduction of OH, test sensitivity and interact...
Laser induced fluorescence (LIF) was utilized for the determination of the densities of Ti atoms and ions (Ti+) in a dc magnetron discharge. The densities were measured under different discharge conditions, namely the discharge current, working pressure and distance from the magnetron target. The total density of species in the discharge was calculated ...
Chirped pulse amplification is increasingly used to produce intense ultrashort laser pulses. When high-efficiency gratings are the dispersive element, as in the LLNL Petawatt laser, their susceptibility to laser induced damage constitutes a limitation on the peak intensities that can be reached. To obtain robust gratings, it is necessary to understand the ...
UV absorption in the combustion phase of spark-ignition engines strongly influences laser-induced-fluorescence measurements and flame-emission techniques because of the attenuation of a laser and/or signal light. This absorption was assessed with spatial, spectral, and temporal resolutions in an optically accessible research engine. ...
UV absorption in the combustion phase of spark-ignition engines strongly influences laser-induced-fluorescence measurements and flame-emission techniques because of the attenuation of a laser and or signal light. This absorption was assessed with spatial, spectral, and temporal resolutions in an optically accessible research engine. ...
We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, ...
Nonlinear absorption through laser-induced breakdown (LIB) offers the possibility of localized energy deposition in linearly transparent media and thus of non-invasive surgery inside the eye. The general sequence of events--plasma formation, stress wave emission, cavitation--is always the same, but the detailed characteristics of these processes depend ...
Laser-induced incandescence is both characterized and demonstrated for the measurement of metal nanoparticle concentration. Reported are the results of an initial characterization of the spectral and temporal signature of the laser-induced incandescence as a function of the excitation laser fluence and wavelength. Validation of the incandescence as a measure of the ...
Spatially resolved laser-induced fluorescence has been used to observe and measure the isotope shift for atomic lithium in the 2/sup 2/Preverse arrow2/sup 2/S transitions. A modified saturated absorption spectrum was also obtained for the ''overlapping'' transitions. The /sup 7/Li-/sup 6/Li isotope shift in the absence ...
High resolution laser induced fluorescence excitation spectra upon absorption in the A1B3u ? X1Ag band of jet-cooled terrylene have been recorded. Precise energies of three vibronic transitions are deduced. Low lying vibrations are found in both electronic states. Rotational constants in ground and excited state are determined by band ...
The ground state density of xenon atoms has been measured by spatially resolved laser-induced fluorescence spectroscopy with two-photon excitation in the diffusion chamber of a magnetized Helicon plasma. This technique allows the authors to directly measure the relative variations of the xenon atom density without any assumptions. A significant neutral gas density depletion ...
The method of laser induced fluorescence used to analyse dissolved organic matter (DOM) in water was discussed. The fluorescence spectrum was normalized by the intensity of Raman scattering for reducing some negative effect induced by the intensity of excitation, the fluorescence absorption by water, and receiving conditions etc. The ...
Excimer laser radiation changes the physical and optical properties of fused silica. These changes include compaction of the glass and induced absorption, both of which have an impact on the expected lifetime of silica lenses used in optical microlithography. We report on our ongoing study of excimer laser induced changes in fused ...
Self-absorption is used in laser induced breakdown spectroscopy to obtain quantitative analytical information. In this approach two plasmas are generated with a laser pulse that is split into two beams separated by a few millimeters and incident on the target material. One of the beams generates plasma that acts as the light source ...
Column densities NH of atomic hydrogen have been derived for 40 OB stars from spectral scans at Lyman alpha obtained by the Copernicus (OAO-3) satellite. The stars are all between 60 and 1100 pc away with a range of mean densities n sub H of 0.01 to 2.5 a...
The present study deals with the study of surface enhanced fluorescence of Tryptophan by Silver Nanoparticles. Absorption and fluorescence studies of Tryptophan with and without Ag-nanoparticles are presented here. Homebuilt Laser Induced Fluorescence (LIF) Spectroscopy setup was used for the fluorescence studies. Calibration plots for ...
Polymers incorporating photochromic molecules are promising materials for flexible optical switches and optical data storage devices. A study on reversible photoswitching of azobenzene incorporated polydimethylsiloxane is carried out using transmittance and UV-VIS absorption measurements. The influence of light intensity on the photoswitching behavior is also investigated. The ...
I develop a Lyman-a radiative transfer (RT) Monte Carlo code for cosmological simulations. High resolution, along with appropriately treated cooling, can result in simulated environments with very high optical depths. Thus, solving the Lyman-a RT problem in cosmological simulations can take an unrealistically long time. For this reason, I develop methods ...
Laser-induced damage in transparent dielectrics leads to the formation of laser-modified material as a result of exposure to extreme localized temperatures and pressures. In this work, we used an infrared thermal imaging system in combination with a fluorescence microscope to map the dynamics of the local surface temperature and fluorescence intensity under cw, UV excitation ...
A classical medical ultrasound system was combined with a pulsed laser source to allow laser-induced ultrasound imaging (optoacoustics). Classical ultrasound is based on reflection and scattering of an incident acoustic pulse at internal tissue structures. Laser-induced ultrasound is generated in situ by heating optical absorbing structures, such as blood ...
the discovery of the binary character of the bright star a-centauri. The period of ~ 250 years that intervenes GMRT observations of several low redshift Damped Lyman alpha systems, based on absorption of radio
a Lyman- alpha absorption hygrometer. [8] Measurements of b on both aircraft were obtained using., 17, 905�922, 2001. Weinstock, E. M., et al., New fast response photofragment fluorescence hygrometer
The RHESSI data show two main periods of GRB emission. ..... D. E. vanden Berk ( PSU), and J. Racusin (PSU) report on behalf of the Swift team: The ..... (GCN 6032), the absence of Lyman-alpha forest absorption at short wavelengths ...
The Quasar Absorption Line Survey of bright sources is an efficient observing program designed to provide a homogeneous data base of absorption features. The data will reveal absorption regions in galaxies, in clusters of galaxies, in voids, in large-scale structures, in Lyman ALPHA clouds, and wi provide ...
The discovery of the second quasar with a redshift greater than 4 is reported. This object, which has an r magnitude of 21.0, was detected on a CCD grism survey. The spectrum of the quasar has strong, relatively narrow (but resolved) emission lines; there is a deep absorption trough about 100 A wide on the blue wing of the Lyman-alpha line; and the ...
The paper presents high-SNR spectroscopic observations of the z = 1.776 absorption system toward the QSO MC 1331+170. Data on C, Si, Fe, O, Mg, and Al at the Lyman-alpha and 21-cm redshift are presented, and the existence of detectable absorption by C and Si in several states of ionization makes it possible to construct a range of ...
The optical depths of the solar H Lyman ..cap alpha.. and the He 584-A lines in interplanetary space are calculated. From these the solar line profiles at Saturn and Uranus are determined. It is found that the solar H Lyman ..cap alpha.. line can be diminished strongly within a spectral region of vertical-bar..delta..lambdavertical-bar<0.2 A from the ...
Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the ...
... Descriptors : *LASER INDUCED FLUORESCENCE, *DIATOMIC MOLECULES ... EXCITATION, THESES, QUENCHING, NITROGEN LASERS. ...
thicket of absorption lines (see examples from Wolfe et al. 1993; ApJ, 404, 480). Many (but not all) of these absorption features are thought to be from the same transition: Lyman (n = 1 to n = 2) in hydrogen. The absorption lines are located at different wavelengths because they arise from different hydrogen ...
often exhibit a dense thicket of absorption lines (see examples from Wolfe et al. 1993; ApJ, 404, 480). Many (but not all) of these absorption features are thought to be from the same transition: Lyman # (n = 1 to n = 2) in hydrogen. The absorption lines are located at di#erent wavelengths because they arise
Previously we have shown that the size of laser induced damage sites in both KDP and SiO2 is largely governed by the duration of the laser pulse which creates them. Here we present a model based on experiment and simulation that accounts for this behavior. Specifically, we show that solid-state laser-supported absorption fronts are ...
Previously we have shown that the size of laser induced damage sites in both KDP and SiO{sub 2} is largely governed by the duration of the laser pulse which creates them. Here we present a model based on experiment and simulation that accounts for this behavior. Specifically, we show that solid-state laser-supported absorption fronts ...
We investigate Lyman-alpha emission from high-redshift galaxies, by combining hydrodynamic simulations with three dimensional radiative transfer calculations. We focus on a set of major mergers of galaxies in the redshift range of z 3 -7, with a mass range of 2-5*10^{12} Msun. The hydrodynamic simulations include star formation, black hole growth, and feedback processes. The ...
We propose high resolution UV spectroscopy of the bright low redshift QSO KUV18217+64 to study selected absorption systems in the low redshift Lyman ALPHA forest. Observations with the G160M grating and GHRS will be used to resolve the strong Lyman ALPHA and Lyman BETA absorption lines that ...
The resistance of PMMA with various concentrations of dibutyl phthalate plasticizer to Nd-laser radiation at a wavelength of 1.06 microns and a pulse duration of 30 ns was studied experimentally. The concentration of centers responsible for destruction is calculated, and the switch-on dynamics of matrix absorption connected with thermoelastic stresses is analyzed. ...
Simultaneous high-speed in-cylinder measurements of laser-induced fluorescence of biacetyl as a fuel tracer and mid-infrared broadband absorption of fuel and combustion products (water and carbon dioxide) using a spark plug probe are compared in an optical engine. The study addresses uncertainties and the applicability of absorption measurements at a ...
Laser induced cavitation bubbles in water results from either dielectric breakdown or the fast evaporation due to radiation absorption. The bubbles expand, reach a maximum radius and then supersonically collapse producing a by shock wave. So far, laser induced cavitation has been observed by ...
We present results from two projects in which we have used the HI 21cm emission line as a tracer of gas-rich galaxy populations in the vicinity of Lyman-? absorbers. In the first case, we examine the HI environment of sbs 1543+593, the nearest damped Lyman-? absorber. We use a vla map of the region around this lsb galaxy which itself shows an extended HI ...
Interstellar/interplanetary neutral H atoms which are observed towards the upwind (UW) and downwind (DW) directions do not originate from the same region of the heliospheric interface. If the neutral/plasma coupling is not negligible, the variations of the plasma properties with the distance to the stagnation line are imprinted in the neutral atoms and in the relationship between the UW and DW ...
The contents of this book are: Semiclassical principles of atomic and molecular spectra; Lasers for spectroscopy; Resonance photoionization spectroscopy; Applications of laser absorption; Laser plasmas for chemical analysis; Laser-induced molecular dissociation; Laser Raman techniques; Laser remote sensing techniques; and Applications for laser-induced ...
Benzene vapor was photolyzed at 248 nm using a pulsed Exciplex laser, and aerosol formation was observed using light scattering. Multiphoton absorption occurs at laser energies >30 MJ cm sup -2 pulse sup -1 , with acetylene as predominant reaction product...
. This could also assist in the analysis of experimental measurements of methods which allow for sample cooling- niques, including UV�vis light absorption, laser-excited fluorescence, laser-induced incandescence, light mobility particle sizer, small angle neutro scattering, and transmission electron microscopy. Proc Combust
Modern laser-spectroscopic techniques usually incorporate one or more laser beams and depend on their radiative interaction with some spectroscopic feature of the gas. Attention is given to laser absorption, laser-induced fluorescence, Rayleigh scattering, and Raman scattering. Consideration is given to UV Rayleigh scattering applied to aerodynamic flows ...
In the near-zero gravity aboard the orbiting Space Shuttle, .... Also, the sample can be squeezed by applying short power pulses to the heating or levitation coils. ..... EXPERIENCE: Following graduation from Cornell University in 1982, .... flow reactor using laser induced fluorescence and laser absorption . ...
Laser-induced Plasma Spectroscopy was performed during the spines ablation of Opuntia by using Nd:YAG microsecond laser pulses. The results show strong absorption in Glochids that causes the intense electronic noise on the spectra. This process is consider suitable for practical elimination of spines in alimentary products like opuntia.
Recent experimental and theoretical investigations of the interaction of light with small particles such as aerosols and hydrosols are discussed in a collection of review essays. Topics addressed include morphology-dependent resonances, spectroscopy of single levitated micron-sized particles, absorption and fluorescence spectroscopy of aerosols, ...
Acoustical waves have been observed in CO2, at initial pressures between 2 and 25 Torr, caused by sudden heating from incident CO2 laser pulses. The effect was observed by monitoring the temperature increase of the window of the absorption cell due to the...
The absorption and fluorescence spectra and fluorescence decay kinetics of Cd(1-x)Mn(x)F2 crystals with x = 0.018, 0.063, 0.084, 0.26 were measured as a function of temperature under argon-ion and nitrogen laser excitation. In addition, laser-induced grat...
Starting from the absorption of laser energy at a subsurface nanoparticle in fused silica, we simulate the consequent buildup of stresses and resulting mechanical material damage . The simulation indicates the formation of micropits with size comparable to a wavelength, similar to experimental observation. Possible mechanisms for enhanced local light absorbtion are discussed.
We report absorption, fluorescence and nonlinear optical properties of fused silica implanted with Ti, Cu and Bi and doses of 1(center dot)10(sup 15) ions/cm(sup 2) to 6(center dot)10(sup 16) ions/cm(sup 2) when irradiated with 532 nm laser light. The flu...
A laser-induced photoacoustic spectroscopy is developed for the direct speciation of transuranic elements in natural aquatic systems. Speciation sensitivities are attained to the sub- mu mol range, e.g., the Am sup 3+ ion with its molar absorption coeffic...
A qualitative LIBS analysis of Prickly Pear is presented. The spectra for Q:Switch regime from cladode and spine are similar, while shows an intense electronic noise due the high absorption in spines for free-running regime.
any coloration, even after several hours of exposure. The absorption spectrum of the photochromic at 308-nm of a 0.05% Ce 3~:CaF~sample, coloration of the crystal was observed due to laser induced measured. The coloration is photo-reversible, and may be bleached by illumination in the defect center
The collision dynamics in collision induced chemical reactions were studied. It was found that reactive systems exhibit a collision induced absorption which enhances the rate of reaction by effectively lowering the activation energy. A classical model was developed that describes the phenomenon correctly which can be used to investigate its various aspects theoretically.
Following a brief discussion of the properties of lasers and a description of measuring techniques, the effects of laser radiation are discussed as they relate to absorption at opaque surfaces, laser-induced particle emission, gas breakdown, damage to transparent materials and effects on biological systems. The concluding chapter discusses applications of ...
The combined effect of electrostriction and radiative absorption in the formation of laser induced gratings in fluids is calculated. For pure electrostrictive gratings, the reflectivity is a damped oscillation with alternately higher and lower maxima. The damping is determined by viscosity and heat transfer. The normalized difference ...
Laser-induced fluorescence (LIF) and electronic absorption spectroscopy (EAS) were used to examine pyrene adsorbed on Al2O3(1120) as a function of surface coverage, temperature, and adlayer order. Temperature-programmed LIF and EAS techniques were employe...
The collisional dynamics of the 5(2)P levels in rubidium has been examined using steady-state laser absorption and spectrally-resolved laser induced fluorescence techniques. State-to-state cross-sections for energy transfer between Zeeman split levels ran...
The resonance transition 2P-2S of the atomic hydrogen (Lyman-alpha emission) is the strongest and most conspicuous feature in the solar EUV spectrum. The Lyman-alpha radiation transfer depends on the resonance scattering from the hydrogen atoms in the atmosphere and on the O2 absorption. Since the Lyman-alpha ...
We present observations of a peculiar Lyman alpha-emitting galaxy at redshift 3.344, discovered in a deep, blind spectroscopic survey for faint Lyman alpha emitters with the Magellan II telescope in the Hubble Ultra Deep Field (HUDF). The galaxy exhibits complex Lyman alpha emission, including an extended, asymmetric component that is ...
Low-resolution GHRS spectra of the UV-bright BL Lac object PKS2155-304 (Bruhweiler et al. 1992) have revealed 5-6 new local Lyman-ALPHA systems, including a complex of 3 lines in the redshift range z=0.053-0.059. The central line at 1285 A is one of the strongest, lowest-redshift Lyman-ALPHA absorption lines known, but no associated ...
Results of a detailed study are presented how the solar H Lyman- radiation infiltrades the lower thermosphere and mesosphere. Wavelength and temperature dependent ab- sorption by molecular oxygen and multiple resonance scattering by atomic hydrogen and the associated Doppler effect is included in a Monte Carlo program describing the radiation transfer in the atmosphere. For ...
An improved Lyman-alpha hygrometer is described, which employs a solar-blind photomultiplier (PM) tube as a detector, ensuring large signal-to-noise ratios and allowing miniaturization of sampling volume. The drawback of the instrument is the relatively wide spectral window. In order to avoid a spurious sensitivity to oxygen density fluctuations, an active filtering cell is ...
The maximal laser power transmitted through polycrystalline silver halide fibers is limited by their IR absorption and optical strength. The mechanisms of the IR absorption and laser-induced breakdown (LIB) thresholds Pc in AgClxBr1-x crystals and polycrystalline fibers were studied. Investigations, including mechanical treatments, heat treatments, and ...
Two-dimensional imaging of CO distributions in combustion gases is demonstrated using planar laser-induced fluorescence. The illumination technique is based on the combination of a nonlinear absorption scheme, in which two photons at 230.1 nm excite several rotational transitions of the B (1)Sigma(+) ? X(1)Sigma(+) system, and the use of an ultraviolet ...
We present a simple theoretical model for the emission from double pulse laser-induced plasmas that was developed to better understand the processes and factors involved in enhancement of plasma emission. In this model, the plasma emission is directly proportional to the square of plasma density, its volume, and the fraction of second laser pulse absorbed through inverse ...
Numerous atomic analytes in plumes produced by pulsed-laser ablation fluoresced upon ArF laser irradiation. The likely mechanism was photoexcitation to levels near the ionization limit. These levels were dense and were probably broadened by the extreme plume density to allow efficient absorption of 193 nm photons. The excited atoms relaxed to intermediate states as the plume ...
Estimation of the local dissociation degree and the local mass-specific enthalpy of a pure oxygen plasma flow determined mainly from laser-induced fluorescence measurements are reported. Measurements have been conducted for several generator parameters in an inductively heated plasma wind tunnel. Additional probe measurements of total pressure together with the deduced ...
Laser-induced fluorescence (LIF) of high-purity fused silica irradiated by ArF excimer laser is studied experimentally. LIF bands of the fused silica centered at 281 nm, 478 nm, and 650 nm are observed simultaneously. Furthermore, the angular distribution of the three fluorescence peaks is examined. Microscopic image of the laser modified fused silica indicates that scattering ...
Laser-induced breakdown spectroscopy (LIBS) measurements of alkali in the high-temperature exhaust of a glass furnace show an attenuation of the Na and K LIBS signals that correlates with the stoichiometry of the bath gas surrounding the spark. The results are explained as being due to (1) a strong increase in the concentration of atomic Na and K, resulting in neutral line ...
Studies on some laser interactions to fluid materials are presented. Firstly, pulsed-laser-induced cavitation bubble in liquid nitrogen is investigated by YAG laser irradiation. High speed schlieren photographs by Imacon-790 are taken to observe the laser-induced bubble dynamics. Bubble and solid wall interactions are also investigated. Based on the results obtained, a novel ...
Biomaterial, such as chitosan, poly lactic acid, etc., containing fluorescence agent was deposited onto biology hard tissue, such as teeth, fingernail of dog or cat, or sapphire substrate by free electron laser induced forward transfer method for direct write marking. Spin-coated biomaterial with fluorescence agent of rhodamin-6G or zinc phthalochyamine ...
In this work, Laser-induced breakdown spectroscopy (LIBS) has been applied to characterization of plasmas generated in air at atmospheric pressure from a calcium hydroxide sample with a known concentration of Mg by using an infrared Nd:YAG laser. The influence of laser irradiance on plasma morphology and emission intensity was studied. Spatially-integrated intensities of Mg ...
The chemical evolution of the high redshift intergalactic and interstellar media of galaxies is studied using QSO absorption lines. The redshift evolution of damped Lyman alpha (DLA) system metallicity is studied down to z=0.5, and no significant increase in metals is found. The CIV/HI ratio in the Lyman alpha forest is investigated at ...
Results of near-simultaneous IUE and Voyager ultraviolet spectrometer (UVS) observations of 3C 273, obtained during the period of 1985 late July-early August are reported. The UVS data show a significant drop in flux for observed wavelengths below 1060 A. This may be due to Lyman continuum absorption in the rest frame of 3C 273. If so, then the lack of ...
We present an empirical model that describes the experimentally observed laser-induced bulk damage and conditioning behavior in deuterated Potassium dihydrogen Phosphate (DKDP) crystals in a self-consistent way. The model expands on an existing nanoabsorber precursor model and the multi-step absorption mechanism to include two populations of absorbing ...
