32 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Fluorescence"  
Results: 1 - 24 next
open access

Data report: Illinois, Indiana, Kentucky, Tennessee, and Ohio. National Uranium Resource Evaluation Program. Hydrogeochemical and stream sediment reconnaissance

Description: This report presents the results of ground water, stream water, and stream sediment reconnaissance in Illinois, Indiana, Kentucky, Tennessee, and Ohio. The following sample types were collected in each state: Illinois - 716 stream sediment, 1046 ground water, 337 stream water; Indiana - 126 stream sediment, 443 ground water, 111 stream water; Kentucky - 4901 stream sediment, 6408 ground water, 3966 stream water; Tennessee - 3309 stream sediment, 3574 ground water, 1584 stream water; Ohio - 1214… more
Date: February 1, 1982
Creator: Sargent, K. A.; Cook, J. R. & Fay, W. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Practical applications of activation analysis and other nuclear techniques

Description: Neeutron activation analysis (NAA) is a versatile, sensitive multielement, usually nondestructive analytical technique used to determine elemental concentrations in a variety of materials. Samples are irradiated with neutrons in a nuclear reactor, removed, and for the nondestructive technique, the induced radioactivity measured. This measurement of ..gamma.. rays emitted from specific radionuclides makes possible the quantitative determination of elements present. The method is described, advan… more
Date: January 1, 1982
Creator: Lyon, W.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Place of HgI/sub 2/ energy-dispersive x-ray detectors

Description: After a review of solid-state conduction counters, in general, and of the history of mercuric iodide, in particular, the theory of operation of solid-state energy-dispersive HgI/sub 2/ detectors is dicusssed. The main factors which limit energy resolution in solid-state compound detectors are considered, including statistical fluctuations in charge generation, the window effect, trapping, inhomogeneities in the detector material, and electronic noise. Potential applications of room-temperature … more
Date: January 1, 1982
Creator: Dabrowski, A. J.; Huth, G. C.; Iwanczyk, J. S.; Kusmiss, J. H.; Barton, J. S.; Szymczyk, J. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Progress report, April 1, 1981 to March 31, 1982

Description: Our experiments on chemical reactions might be described by a laser specialist as pump and probe experiments. The pump process is a photodissociation and the probe process is a laser induced fluorescence (LIF). Both these processes would be somewhat limited if they were confined to one photon excitations. For example, to probe vibrationally and rotationally excited CO molecules one can conveniently use Bernheim's technique of exciting the A'..pi.. reverse arrow X'..sigma.. transition in CO by a… more
Date: January 1, 1982
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

On-line composition with laser-based techniques

Description: Current methods for determining the composition of coal gasification streams generally involve sampling, some treatment, and inherent delay times prior to analysis. Optical instrumentation, on the other hand, provides the potential for on-line, rapid-response monitoring of gasifier streams. Among the optical technques that appear quite promising for this application are coherent anti-Stokes Raman scattering (CARS), laser-induced breakdown spectroscopy (LIBS), Fourier transform infrared spectros… more
Date: January 1, 1982
Creator: Finch, F.T. & Hartford, A. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Development of significantly improved catalysts for coal liquefaction and upgrading of coal extracts

Description: During 1979-80, a new generation of very active, long-lived catlaysts for hydrotrating was discovered at the Stamford Research Laboratories of the American Cyanamid Company. The catalysts are based on a unique substrate prepared in bead form from a rehydratable alumina. Their spherical shape, crush strength, and abrasion resistance seem ideally suited for the ebullated bed reactors used in the H-COAL process developed by Hydrocarbon Research, Inc. (HRI). The beads have internal pore structures … more
Date: January 1, 1982
Creator: Sinha, V. T.; Kutzenco, P. D.; Preston, W. J.; Brinen, J. S.; Graham, S. W.; Butensky, M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Investigations of glass structure using fluorescence line narrowing and moleuclar dynamics simulations

Description: The local structure at individual ion sites in simple and multicomponent glasses is simulated using methods of molecular dynamics. Computer simulations of fluoroberyllate glasses predict a range of ion separations and coordination numbers that increases with increasing complexity of the glass composition. This occurs at both glass forming and glass modifying cation sites. Laser-induced fluorescence line-narrowing techniques provide a unique probe of the local environments of selected subsets of… more
Date: July 2, 1982
Creator: Weber, M. J. & Brawer, S. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Resonance-fluorescence kinetic study of oxygen atom + hydrocarbon reactions, V: O(/sup 3/P) + Neopentane (415-922K)

Description: Absolute values of the rate constants for the reaction of O(/sup 3/P) with neo-C/sub 5/H/sub 12/ were determined directly with the use of the complementary techniques: flash photolysis (FP) and discharge flow (DF). The O-atoms were monitored via resonance fluorescence (RF) in both systems, allowing experiments to be carried out at very low (0). Secondary reactions were averted in this way, and the rate data thus obtained were stoichiometry-free. The DF-RF experiments were performed over the tem… more
Date: January 1, 1982
Creator: Michael, J. V.; Keil, D. G. & Klemm, R. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Synchronous detection of laser-induced fluorescence

Description: Many toxic or carcinogenic organic molecules have large absorption and fluorescence emission cross sections and can thus be detected by laser-induced fluorescence (LIF) in liquid samples at parts-per-billion levels or better. The technique of synchronous detection of laser-induced fluorescence (SDLIF) provides a way to distinguish between the fluorescence from a toxic molecule and the fluorescence from a background substance. This is done by synchronously scanning the laser excitation and fluor… more
Date: January 1, 1982
Creator: Quigley, G.P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fluorescent scattering by molecules embedded in small particles. Progress report, February 1, 1981-January 31, 1982

Description: In earlier work a model of fluorescent and Raman scattering by active molecules represented as classical electric dipoles embedded in small particles was developed. The intensity and angular distribution of the inelastically scattered radiation was shown to depend on the geometric and optical properties of the particle. The model was originally developed for particles having spherical shape and later extended to concentric spheres, cylinders, and prolate spheroids. The active molecules were ori… more
Date: January 31, 1982
Creator: Chew, H. & McNulty, P.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Photochemistry of 1 and 2-(2-methylphenyl)-1,6-heptadiene. [4a-methyl-1,2,3,4,4a,9,10,10a-octahydrophenanthrene]

Description: In an attempt to synthesize partially saturated phenanthrene derivatives by an intramolecular Diels-Alder reaction between a photochemically produced o-xylylene (diene) and a tethered dienophile, it was found that 1 and 2 underwent a photochemically allowed (2 + 2) cycloaddition. Irradiation of 1 gave 6-(2-methylphenyl)bicyclo(3.2.0)heptane in 86% yield. Upon irradiation of 2, a benzvalene rearrangement of 2 first took place, producing the meta isomer 2-(3-methylphenyl)-1,6-heptadiene, followed… more
Date: January 1, 1982
Creator: Barrows, R. D. & Hornback, J. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effect of oxygen monolayer coverages on titanium sputtering yields as determined by simultaneous laser fluorescence and auger measurements

Description: The presence of an oxide layer can strongly influence the charge-state of species ejected from ion-bombarded metal surfaces, as well as the total sputtering yield. These quantities directly affect the influx of metallic impurities from the wall region into the plasmas of fusion devices. Surface coverage can also modify the distribution of sputtered atoms among electronic states and thus the apparent impurity density detected by the laser fluorescence spectroscopy (LFS) technique. The measuremen… more
Date: January 1, 1982
Creator: Pellin, M. J.; Young, C. E.; Mendelsohn, M. H.; Gruen, D. M.; Wright, R. B. & DeWald, A. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Oxygen and titanium sputtering yields as determined by laser fluorescence and Auger electron spectroscopy for monolayer oxygen coverage of polycrystalline Ti

Description: The presence of an oxide layer can strongly influence the charge-state of species ejected from ion-bombarded metal surfaces, as well as the total sputtering yield. These quantities directly affect the influx of metallic impurities from the wall region into the plasmas of fusion devices. Surface coverage can also modify the distribution of sputtered atoms among electronic states and thus the apparent impurity density detected by the laser fluorescence spectroscopy (LFS) technique. The measuremen… more
Date: January 1, 1982
Creator: Pellin, M. J.; Young, C. E.; Mendelsohn, M. H.; Gruen, D. M.; Wright, R. B. & DeWald, A. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Uses of synchrotron radiation

Description: X-ray fluorescence has long been used as a technique for elemental analysis. X-ray fluorescence techniques have a number of features that make them attractive for application to biomedical samples. In the past few years synchrotron radiation x-ray sources have been developed and, because of their properties, their use can improve the sensitivity for trace element analysis by two to three orders of magnitude. Also, synchrotron radiation will make possible an x-ray microprobe with resolution in t… more
Date: January 1, 1982
Creator: Gordon, B. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Early history of physics with accelerators

Description: The early history of physics at accelerators is reviewed, with emphasis on three experiments which have had a profound influence on our veiw of the structure of matter: The Franck and Hertz experiment opening practical ways of studying nuclear disintegration, and the discovery of the del/sup + +/ isobar of the proton by Fermi and collaborators, revealing structure in the nucleon. Fermi's work is illustrated by pages from his notebooks.
Date: January 1, 1982
Creator: Anderson, H.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Laser detection of toxic molecules and carcinogens

Description: Fluorescence from large organic molecules is broadband and relatively structureless. Thus, the detection of hazardous molecules in various environments using laser-induced fluorescence is difficult because of obscuration from other fluorescing sources (paints, other impurities, etc.). Laser-optical techniques that can be used to avoid this problem are discussed. The techniques of Synchronous Detection of Laser-Induced Fluorescence (SDLIF), and Resonant Raman Scattering are discussed. It is conc… more
Date: January 1, 1982
Creator: Quigley, G.P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Metal-atom fluorescence from the quenching of metastable rare gases by metal carbonyls

Description: A flowing afterglow apparatus was used to study the metal fluorescence resulting from the quenching of metastable rare-gas states by metal carbonyls. The data from the quenching or argon, neon, and helium by iron and nickel carbonyl agreed well with a restricted degree of freedom model indicating a concerted bond-breaking dissociation.
Date: November 1, 1982
Creator: Hollingsworth, W.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Trace element measurements with synchrotron radiation

Description: Aspects of the application of synchrotron radiation to trace element determinations by x-ray fluorescence have been investigated using beams from the Cornell facility, CHESS. Fluoresced x rays were detected with a Si(Li) detector placed 4 cm from the target at 90/sup 0/ to the beam. Thick samples of NBS Standard Reference Materials were used to calibrate trace element sensitivity and estimate minimum detectable limits for this method.
Date: January 1, 1982
Creator: Hanson, A. L.; Kraner, H. W.; Jones, K. W.; Gordon, B. M. & Mills, R. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design considerations for an x-ray microprobe

Description: The optical design of a fluorescent microprobe covering the x-ray region from 2 to 16 keV is considered for the NSLS x-ray ring. The limit on detectability is from total flux (photons/..mu..m/sup 2/) and several design choices are considered to match the optical system to the storage ring to maximize throughput. The tradeoffs in image quality and energy resolution of these designs have been considered and within these constraints two firm proposals are presented.
Date: January 1, 1982
Creator: Howells, M.R. & Hastings, J.B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Application of XRF to measure strontium in human bone in vivo

Description: As a basis for better understanding the role that Sr fulfills in human body, it is desirable to measure directly the main Sr store in human body. Although strontium is omnipresent in human tissues, 99% is stored inthe mineral portion of the bone. In the present study x-ray fluorescence (XRF) was applied to measure the strontium content of the tibial shaft in vivo. The feasibility studies showed that normal levels of stable strontium in the bone can be measured successfully.
Date: January 1, 1982
Creator: Wielopolski, L.; Vartsky, D.; Yasumura, S. & Cohn, S.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Laser-based instrumentation for the detection of chemical agents

Description: Several laser-based techniques are being evaluated for the remote, point, and surface detection of chemical agents. Among the methods under investigation are optoacoustic spectroscopy, laser-induced breakdown spectroscopy (LIBS), and synchronous detection of laser-induced fluorescence (SDLIF). Optoacoustic detection has already been shown to be capable of extremely sensitive point detection. Its application to remote sensing of chemical agents is currently being evaluated. Atomic emission from … more
Date: January 1, 1982
Creator: Hartford Jr., A.; Sander, R. K.; Quigley, G. P.; Radziemski, L. J. & Cremers, D. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Multiple-photon laser-induced fluorescence. [HS and DS radicals]

Description: The technique of multiple-photon laser-induced fluorescence has been used to study the spectroscopy and dynamics of atoms, molecules, and free radicals. Among the species investigated were iodine atoms (I), carbon monoxide (CO), molecular iodine (I/sub 2/), and HS and DS radicals. 7 figures.
Date: January 1, 1982
Creator: Tiee, J.J.; Ferris, M. J.; Loge, G. W.; Wampler, F. B. & Hartford, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Outer-shell excitation mechanisms and static-mode laser-fluorescence spectroscopy of sputtered atoms

Description: A review of the literature on atoms sputtered in electronically excited states is given together with a discussion of various mechanisms that have been proposed to account for the observations. The major observational features that have emerged from the older studies may be summarized as follows: (1) the kinetic energies of neutral atoms in highly excited electronic states are 1-2 orders of magnitude greater than E/sub b/, the surface binding energy; (2) relative yields show approximately expon… more
Date: January 1, 1982
Creator: Gruen, D. M.; Pellin, M. J.; Young, C. E.; Mendelsohn, M. H. & DeWald, A. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Static-mode laser-fluorescence spectroscopy: a new technique for studying excitation mechanisms in particle-surface collisions

Description: The recent development of static mode laser fluorescence spectroscopy provides a new technique for measuring the hitherto inaccessible distributions among low lying excited electronic energy levels at well defined surface oxygen coverages. Because of the sensitivity and selectivity of the LFS method, it is now possible to probe the effects on excitation coefficients of oxygen coverages at monolayer levels using simultaneous Auger measurements which in turn can be correlated with specific adsorb… more
Date: January 1, 1982
Creator: Gruen, D. M.; Pellin, M. J.; Young, C. E. & Mendelsohn, M. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen