Laser Applications to Chemical Analysis最新文献_第8页

Laser Based Refractive Index Detection in Capillary Tubes 基于激光的毛细管折射率检测

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1992.pd7

A. Bruno

引用次数: 0

Degenerate Four-Wave Mixing in a Methane/Air Flame Using a Regeneratively Mode-Locked Ti:Sapphire Laser 利用再生锁模钛蓝宝石激光器在甲烷/空气火焰中的简并四波混频

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.fb.3

M. Linne, G. Fiechtner

引用次数: 0

Time Resolved Spectra of Lightning Simulation in Titan's Atmosphere 土卫六大气中闪电模拟的时间分辨光谱

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.tuc4

H. S. Lakkaraju, D. Jebens, W. Borucki, C. P. McKay

引用次数: 0

Molecular Surface Analysis Utilizing Laser Desorption/Laser Ionization 利用激光解吸/激光电离进行分子表面分析

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1992.thb4

K. Lykke, P. Wurz, D. Parker, J. E. Hunt, M. Pellin, D. Gruen

{"title":"Molecular Surface Analysis Utilizing Laser Desorption/Laser Ionization","authors":"K. Lykke, P. Wurz, D. Parker, J. E. Hunt, M. Pellin, D. Gruen","doi":"10.1364/laca.1992.thb4","DOIUrl":"https://doi.org/10.1364/laca.1992.thb4","url":null,"abstract":"The ability to analyze surface elemental composition has existed for some time. The various methods include Auger Electron Spectroscopy (AES), Secondary Ion Mass Spectrometry (SIMS), and many more.1 However, molecular surface analysis is only now achieving the same sensitivity and selectivity. Molecular surface analysis often utilizes various optical probes: IR Reflection Absorption Spectroscopy, Sum-Frequency (or Second Harmonic) Generation Spectroscopy on Surfaces, etc. These techniques are generally lacking species-specific information. Another approach is to remove the molecule from the surface and probe it in the gas phase, e.g., with state- of-the-art mass spectrometry. Since mass spectrometry offers high resolution and high sensitivity, the remaining problems are removal of the molecule from the surface and ionization without alteration of the molecule (e.g., fragmentation). These pose serious complications for large molecules, in particular. Furthermore, if the molecule of interest is only a minor constituent of a sample, mass resolution and sensitivity are not sufficient for species identification, and a pre- selection in the ionization is often necessary. Our solution is to employ lasers for both desorption from the sample and ionization (post-ionization) of the gas-phase species. The ability to choose the wavelength and intensity of the desorption laser and the post-ionization laser allows for proper tailoring to the needs of the investigation. This will be demonstrated with two examples. First, a vulcanizate (rubber) will be analyzed with a time-of-flight mass spectrometer for the organic additives present in minor concentrations in the near-surface region. Second, a new class of carbon molecules (fullerenes) will be examined with a Fourier transform mass spectrometer.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115500389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Photoacoustic, Photothermal Beam Deflection and Flash Photolytic- High Pressure Rate Studies Done with a Pulsed Nd:YAG Laser 光声，光热光束偏转和闪光光解-脉冲Nd:YAG激光器的高压速率研究

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1992.pd3

S. J. Isak, K. B. Reddy, Rüdiger Hoffman, G. Kónya, R. van Eldik, E. Eyring

{"title":"Photoacoustic, Photothermal Beam Deflection and Flash Photolytic- High Pressure Rate Studies Done with a Pulsed Nd:YAG Laser","authors":"S. J. Isak, K. B. Reddy, Rüdiger Hoffman, G. Kónya, R. van Eldik, E. Eyring","doi":"10.1364/laca.1992.pd3","DOIUrl":"https://doi.org/10.1364/laca.1992.pd3","url":null,"abstract":"A combination of photoacoustic (PA), photothermal beam deflection (PBD) and fluorimetric spectroscopic measurements has been used to determine fluorescence quantum yields for cresyl violet perchlorate in methanolic and aqueous solutions. A concentration dependence of the fluorescence quantum yield is found to be significant. The same Quanta Ray DCR-2 Nd:YAG laser used in the PA and PBD experiments has been the flash photolysis light source at λ = 355 nm for a rate study of ring closure reactions of Mo(CO)5L complexes where L is one of several substituted 2,2'-bipyridine chelating ligands. The laser pulse creates the Mo(CO)5L species from Mo(CO)6/L dissolved in toluene. The sample liquid is in a compressible quartz pill-box cell housed in a steel autoclave that can be pressurized to 200 MPa. Values of the activation parameters ΔS# and ΔV# for the rate determining ring closure reaction are small and negative for two of the 2,2'-bipyridine ligands supporting the concept of an associative interchange mechanism for CO extrusion. For another, bulkier 2,2'-bipyridine type ligand ΔV# is small and positive suggesting a dissociative interchange mechanism. These results demonstrate a changeover in reaction mechanism with changes in steric hindrance.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115287872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Silicon Photopotential Relaxation In Different-Composition Electrolytes 不同成分电解质中的硅光势弛豫

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.tuc7

A. Maslov, Y. Petrov, V. Pustovoy, A. Prokhorov

引用次数: 0

Analysis of Ag/Au Alloy by Sputter Initiated Laser Ionization Spectrometry and Secondary Ion Mass Spectrometry 溅射激光电离光谱法和二次离子质谱法分析银/金合金

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.tub3

G. Havrilla, M. Nicholas, S. Bryan, J. Pruett

引用次数: 0

Surface Enhanced and Unenhanced Raman Scattering of Alkanethiols Adsorbed on Silver and Gold Surfaces 链烷硫醇在银和金表面吸附的表面增强和非增强拉曼散射

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.ma2

C. R. Johnston, Mark A. Bryant, J. Pemberton

引用次数: 0

Monte Carlo Model of a Single Molecule Counting Experiment 单分子计数实验的蒙特卡罗模型

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.thd.2

L. Davis, Li-Qiang Li

引用次数: 2

Chemical Species from Tritium-Breeding Compacts by Raman Spectroscopy 用拉曼光谱分析氚繁殖致密物中的化学物质

Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.tub.6

D. Taylor, F. Steinkruger, David E Christiansen, D. Gettemy

{"title":"Chemical Species from Tritium-Breeding Compacts by Raman Spectroscopy","authors":"D. Taylor, F. Steinkruger, David E Christiansen, D. Gettemy","doi":"10.1364/laca.1994.tub.6","DOIUrl":"https://doi.org/10.1364/laca.1994.tub.6","url":null,"abstract":"The retention of tritium in reactor breeding compacts has been studied in these experiments at conditions simulating nuclear reactor accidents, and the experimental results have been used to determine New Production Reactor safety envelopes. The tritium-breeding compacts tested contain thousands of spherical particles within a carbonaceous matrix; each particle is fabricated as a kernel of lithium aluminate, enriched in 6Li for breeding tritium by (n,α) reaction, surrounded by consecutive shells of porous carbon, pyrolytic carbon, silicon carbide, and pyrolytic carbon to retain the tritium during breeding. The experiments demonstrated that in an accident with a sudden reactor temperature jump to 1300°C, more than 99% of the tritium would be retained within the compact for over 50 hours, which is ample time to bring such an accident under control. In these experiments, chemical species released from the compacts were measured by laser-Raman spectroscopy to enable design of chemical safety systems. Chemical species that were observed at intermediate temperatures, including H2O, H2, CO, and hydrocarbons, resulted from compact exposure to air, whereas species released at high temperatures, including HT and CO, originated within the particles. The Raman data identified the dominant tritiated species to be HT, at concentrations commensurate with measurements of total tritium using ion chambers and scintillation counter. These tests attained Raman detectability as low as 6.4 parts-per-million (ppm) for HT.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124907559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0