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Molecular rotation in organized media: surface monolayers, liquid crystals and micelles 有组织介质中的分子旋转:表面单层、液晶和胶束
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.wb2
M. Wirth, Shiow-Hwa, J. Burbage
{"title":"Molecular rotation in organized media: surface monolayers, liquid crystals and micelles","authors":"M. Wirth, Shiow-Hwa, J. Burbage","doi":"10.1364/laca.1990.wb2","DOIUrl":"https://doi.org/10.1364/laca.1990.wb2","url":null,"abstract":"Molecular rotation in ordinary liquids is generally understood, albeit imperfectly. However, molecular rotation in more complicated and intriguing media, such as surface monolayers, liquid crystals and organized surfactants, is less understood. These media are structured, thus affecting the way a solute rotates. To study molecular rotation, the correlation of the orientations of 2 transition dipoles of a solute is measured as a function of time. The results are interpreted using the spherical harmonics to describe the decay of the correlation function. The keys to describing rotation in complicated media are 1) highly quantitative and sensitive measurements of the rotational correlation function and 2) development of mathematical models to describe hindered rotation. In this paper, the rotational behavior of solute probes in bonded chromatographic phases, micelles and liquid crystals is described and contrasted with rotational behavior in ordinary liquids.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"92 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":"123608964","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
Ultrasensitive Analysis Of Trace Atmospheric Species Using Diode Lasers: A Comparison Of High Frequency Modulation Techniques. 利用二极管激光器对痕量大气物质进行超灵敏分析:高频调制技术的比较。
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.wa7
D. S. Bomse, J. A. Silver, A. Stanton
{"title":"Ultrasensitive Analysis Of Trace Atmospheric Species Using Diode Lasers: A Comparison Of High Frequency Modulation Techniques.","authors":"D. S. Bomse, J. A. Silver, A. Stanton","doi":"10.1364/laca.1990.wa7","DOIUrl":"https://doi.org/10.1364/laca.1990.wa7","url":null,"abstract":"Numerous frequency modulation techniques are now available to overcome the large excess noise inherent to diode laser operation at low frequencies. In some cases, shot noise limited laser performance has been obtained with measured absorbances as low as 10-7. Combination of these novel methods with the long (10-100 m) optical paths provided by multipass cells makes feasible sub-part-per-billion detectivities for many gaseous compounds.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"77 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":"129808430","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
Laser Spectroscopy for Practical Isotope Ratio Measurements 实用同位素比值测量的激光光谱学
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.wb.3
R. Shaw, C. M. Barshick, J. P. Young, J. Ramsey
{"title":"Laser Spectroscopy for Practical Isotope Ratio Measurements","authors":"R. Shaw, C. M. Barshick, J. P. Young, J. Ramsey","doi":"10.1364/laca.1994.wb.3","DOIUrl":"https://doi.org/10.1364/laca.1994.wb.3","url":null,"abstract":"Isotope ratio measurements are typically accomplished by methods that are seldom amenable to field use. An example is thermal ionization mass spectrometry (TIMS)i where solid samples are dissolved, a filament loaded with the resulting solution, the filament mounted in a source chamber, the mass spectrometer pumped to low pressure, the filament heated to produce analyte ions, and finally the ions separated according to mass in either space or time for counting. There is a need for field mass spectrometric measurements, particularly in the environmental remediation arena, where near real time results can save time and reduce costs. Miniaturized ion traps that can be deployed for field measurement of organics have been reported. 2 There currently are no isotope ratio methods in field use.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"1 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":"130207984","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
Applications Of Fourier Transform Raman Spectroscopy To Polymeric Systems 傅里叶变换拉曼光谱在聚合物体系中的应用
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.wb1
J. Rabolt
{"title":"Applications Of Fourier Transform Raman Spectroscopy To Polymeric Systems","authors":"J. Rabolt","doi":"10.1364/laca.1990.wb1","DOIUrl":"https://doi.org/10.1364/laca.1990.wb1","url":null,"abstract":"Raman spectroscopy is an extremely sensitive technique used to characterize structure and local order in polymeric systems. Unfortunately it has never attained the routine analytical utility which other techniques such as infrared spectroscopy have due to the presence, in most long chain polymers, of trace amounts of impurities (chemical initiators, catalyst residues, stabilizers, etc.). These impurities give rise to strong fluorescence in the visible which interferes with the recording of a Raman spectrum in this region. Recently, however, with the advent of cw Nd:YAG lasers and low temperature InGaAs detectors, Raman spectroscopy in the near infrared has become possible. Near infrared photons do not give rise to fluorescence and hence Raman scattering from polymeric materials containing chromophores either as an inherent part of their molecular structure or as an impurity can be routinely obtained. The spectral distribution of the scattered light is obtained using a commercially available Fourier transform IR (FTIR) spectrometer thus giving name to the technique. Since the inception of this technique in 1985, Fourier transform Raman spectroscopy has been utilized to investigate the structure of biomolecules, the nature of order-disorder transitions in polysilanes and the orientation of side chain chromophores in carbon backbone polymers useful for nonlinear optical applications. Several examples will be used to explicitly illustrate the utility of this new spectroscopic technique.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"24 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":"130008092","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
The Sensitive Detection and Analyses of SiH3 and SiH Radicals Using Multiphoton Ionization Spectroscopy 多光子电离光谱对SiH3和SiH自由基的灵敏检测和分析
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.mb5
J. W. Hudgens, B. Tsai, Russell D. Johnson
{"title":"The Sensitive Detection and Analyses of SiH3 and SiH Radicals Using Multiphoton Ionization Spectroscopy","authors":"J. W. Hudgens, B. Tsai, Russell D. Johnson","doi":"10.1364/laca.1990.mb5","DOIUrl":"https://doi.org/10.1364/laca.1990.mb5","url":null,"abstract":"The free radicals, silyl (SiH3) and silylidyne (SiH), play important roles at the gas-surface interface during the chemical vapor deposition (CVD) of silicon films from silane, SiH4. We will report recent experiments that enable resonance enhanced multiphoton ionization (REMPI) spectroscopy to detect these radicals with great sensitivity. These newly developed REMPI detection methods should allow experimentalists to measure the relative concentration profile of SiH3, SiH, and Si radicals in the same experimental configuration and under the same conditions. For the SiH3 radical the new spectra will also permit temperature measurements.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"13 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":"120964433","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
Surface Raman Scattering as a Probe of Metal Surface Chemistry 表面拉曼散射作为金属表面化学的探针
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1992.thb1
J. Pemberton
{"title":"Surface Raman Scattering as a Probe of Metal Surface Chemistry","authors":"J. Pemberton","doi":"10.1364/laca.1992.thb1","DOIUrl":"https://doi.org/10.1364/laca.1992.thb1","url":null,"abstract":"Raman scattering is an attractive probe of surface and interfacial chemistry at metals due to the high degree of molecular specificity inherent in the results. One aspect of Raman scattering that enhances its utility for the study of metal surfaces is the ability to deduce orientational information about molecules at these metal surfaces from the presence of oriented electric fields at these surfaces with which selective vibrational modes can couple. These \"surface selection rules\" have been both theoretically described and experimentally validated for a variety of metal surfaces. Given the wealth of information available from such studies, potential applications for surface Raman scattering span the range from electrochemical to catalytic systems. Thus, considerable effort has been expended in an attempt to develop Raman scattering for the study of surface and interfacial phenomena. These efforts have largely been focused on overcoming problems attendant to sensitivity and selectivity for the interface in the presence of the bulk environment.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"87 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":"121173678","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
Near-field Optical Measurements at the Liquid/Air Interface 液体/空气界面的近场光学测量
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.wa.3
M. Seaver, A. E. Frost, M. Duncan
{"title":"Near-field Optical Measurements at the Liquid/Air Interface","authors":"M. Seaver, A. E. Frost, M. Duncan","doi":"10.1364/laca.1994.wa.3","DOIUrl":"https://doi.org/10.1364/laca.1994.wa.3","url":null,"abstract":"Near-field optical microscopy offers the benefit of dramatically improved optical resolution [1] in exchange for working in close proximity (10-50nm) to a thin sample (<20nm). Monolayers at the liquid/air interface fulfill the thin sample criterion and are spectroscopically disctict from the supporting liquid. However, the mobility of the interface suggests that when a tapered probe approaches closely, attractive forces may cause the interface to jump up and submerge the probe at probe-sample spacings much greater than the required working distance for near-field optics. We detect the evanescent field decay above the liquid/air interfaces for glycerol, mineral oil, and water. The ability to measure these evanescent decays demonstrates that near-field approach to the liquid/air interface is possible. The measured evanescent decay lengths agree well with the predicted values. The presence of gravity waves in deep (1-2 cm) liquid samples sets a lower limit on the distance of closest approach but does not prevent near-field measurements.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"13 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":"128526823","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
Comparison of Laser Raman Measurements and Fluid Dynamic Calculations in the Characterization of Atmospheric Pressure CVD Flow Reactor 激光拉曼测量与流体动力学计算在常压CVD流动反应器表征中的比较
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1992.wc2
W. V. Von Drasek, B. Jurcik, G. Jursich
{"title":"Comparison of Laser Raman Measurements and Fluid Dynamic Calculations in the Characterization of Atmospheric Pressure CVD Flow Reactor","authors":"W. V. Von Drasek, B. Jurcik, G. Jursich","doi":"10.1364/laca.1992.wc2","DOIUrl":"https://doi.org/10.1364/laca.1992.wc2","url":null,"abstract":"Gas flow dynamic information is obtained on an atmospheric pressure flow reactor. Density spatial profiles have been both predicted by modeling and measured experimentally using spontaneous Raman spectroscopy.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"4 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":"131555831","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
Do You Really Know What You Are Looking At - "True" or "False" Signals in Laser-Enhanced Ionization Spectrometry 你真的知道你在看什么-激光增强电离光谱中的“真”或“假”信号吗
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1990.tua7
O. Axner, S. Sjöström
{"title":"Do You Really Know What You Are Looking At - \"True\" or \"False\" Signals in Laser-Enhanced Ionization Spectrometry","authors":"O. Axner, S. Sjöström","doi":"10.1364/laca.1990.tua7","DOIUrl":"https://doi.org/10.1364/laca.1990.tua7","url":null,"abstract":"\u0000 \"Things are not always what they seem to be\"\u0000 - is a phrase which particularly concerns spectroscopists. This is nicely illustrated by the present paper which discusses and exemplifies a situation which, for more than a decade, has passed virtually unnoticed within the community of spectroscopists which are working with ionization techniques in flames, especially the Laser-Enhanced Ionization technique, (LEI), namely the influence of scattered laser light.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"59 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":"129346245","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
A 30 Hz CARS System for Concentration and Temperature Measurements in Supersonic, Turbulent, H2/Air Combustion 用于超音速，湍流，H2/空气燃烧浓度和温度测量的30 Hz CARS系统
Laser Applications to Chemical Analysis Pub Date : 1900-01-01 DOI: 10.1364/laca.1994.fb.4
M. Smith, Adele Cutler, M. Millard, G. Northam
{"title":"A 30 Hz CARS System for Concentration and Temperature Measurements in Supersonic, Turbulent, H2/Air Combustion","authors":"M. Smith, Adele Cutler, M. Millard, G. Northam","doi":"10.1364/laca.1994.fb.4","DOIUrl":"https://doi.org/10.1364/laca.1994.fb.4","url":null,"abstract":"CARS has become perhaps the most common non-intrusive laser diagnostic\u0000 technique used for the analysis of reacting gas flows.1-4\u0000 This paper describes the design and calibration of a dual broadband\u0000 CARS system assembled to measure single-point, single-shot,\u0000 temperature and species concentration in a simulated hydrogen-fueled\u0000 scramjet (Supersonic Combustion RamJET) engine model. No scramjet data\u0000 are included in this paper. However, the optical system design\u0000 features driven by the scramjet engine test environment are discussed.\u0000 During calibration, temperatures and relative concentrations of\u0000 N2 were derived by fitting single-shot CARS spectra\u0000 acquired at 30 Hz. This optical system was derived in part from a\u0000 previous 10 Hz system designed for thermometry only5. Since\u0000 N2 concentrations were found by spectral fitting, they were\u0000 not subject to problems of beam steering, or beam attenuation. These\u0000 problems, common in situations with high turbulence levels and\u0000 windows, interfere with concentration measurement strategies that\u0000 depend on acquiring absolute CARS signal intensities. In fuel-rich\u0000 conditions, single-shot temperatures were also found independently by\u0000 fitting H2 CARS spectra.","PeriodicalId":252738,"journal":{"name":"Laser Applications to Chemical Analysis","volume":"1 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":"129280641","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
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