Showing papers in "Applied Spectroscopy Reviews in 1978"
TL;DR: In this paper, the authors present a review of CARS spectroscopy of gases in the context of biological and fluorescent materials in dilute solution with an accuracy as low as ∼ 10−7 M.
Abstract: Coherent anti-Stokes Raman spectroscopy, or CARS as it has come to be known, is a relatively new spectroscopic technique which has gained considerable interest over the past few years because of its potential use as a powerful analytical tool and because of its unique and curious properties [1–98], Several review articles on the subject have been written recently [4, 30, 33, 35, 49, 67, 72, 90]. Some papers have attempted to describe the theoretical background [30, 33] and others have surveyed the entire subject matter [4, 35, 49, 67, 72, 90]. In this report we will review only CARS spectroscopy of gases. However, because of recent progress it might be well to at least reference some new results [18–21, 42, 47, 66] in resonance and “normal” CARS of biological and fluorescent materials in dilute solution (as low as ∼ 10−7 M). Moreover, since the emphasis of this paper is on applications, we will not attempt to derive the theory or the principles behind CARS but merely describe the results.
29 citations
TL;DR: In this paper, the authors describe the development of tunable dye lasers and the new science of nonlinear optics, which has been made possible by the development and use of laser technology for spectroscopic experiments.
Abstract: Since laser action was first achieved two decades ago, technological developments have improved the versatility of laser devices so that today we are able to design spectroscopic experiments largely without concern for the limitations of the irradiation source. Further, the development of laser techniques has presented new opportunities for spectroscopic research because of the new and unique properties of laser radiation. Much of the progress has been made possible through the development of tunable dye lasers and the new science of nonlinear optics. Lasers currently provide the purest, most intense sources of radiation while still offering tunability over a wide spectral range, in particular the region 150 to 11, 000 nm. Also, the special conditions of laser operation have allowed the generation of the shortest pulses known from any source of energy down to Fourier-transform-limited single pulses of ∼10−13 sec duration.
10 citations
TL;DR: A review of the application of rapid scanning spectrometers (RSS) to atomic spectroanalytical analysis can be found in this paper, where the optical characteristics of the RSS, as well as the analytical results are discussed.
Abstract: Determinations of metal content by single element atomic spectroscopy are well-established procedures in analytical laboratories. However, there has been considerable interest in methods for simultaneous multielement determinations as indicated by a recent review [1]. Correspondingly, much effort has been devoted to the development of detectors for multielement systems [2–8]. This review will report the application of rapid scanning spectrometers (RSS) to atomic spectroanalytical analysis. An instrument of this type can scan a selected wavelength window or region on a time scale ranging from a few microseconds to several seconds [4]. The scope of this review will be limited to RSS employing a mechanical means of rapid scanning, although much attention has been directed toward imaging devices such as the Vidicon tube and photodiode arrays [6–8]. The optical characteristics of the spectrometers, as well as the analytical results, will be discussed.
2 citations
TL;DR: Linear dichroism is the phenomenon of anisotropic absorption of light as mentioned in this paper, where the absorption intensity is proportional to the square of the scalar product between the electric field vector of the light and a molecule-characteristic transition moment vector.
Abstract: Linear dichroism is the phenomenon of anisotropic absorption of light. It is shown by materials containing oriented molecules for which the absorption varies with the direction. The absorption intensity is proportional to the square of the scalar product between the electric field vector of the light and a molecule-characteristic transition moment vector, the absorption being maximum when the light vector is polarized parallel to the transition moment and zero when perpendicular to it. Linear dichroism can therefore provide (1) directions of transition moments when the molecule orientation is known (spectroscopic applications), or (2) information on molecular orientation when the transition moments are known (structural applications). Both applications are useful in several chemical systems, but so far the use of linear dichroism has been confined to a relatively small number of specialized laboratories, not least because of a lack of appropriate commercial instruments. Plane-polarized spectra have long been measured on crystals and other well-oriented materials, but systems with less complete orientation have usually been studied by birefringence which has allowed greater sensitivity. Birefringence and linear dichroism are related by the dispersion equations and therefore in principle contain the same basic information. However, linear dichroism is better suited for practical use since it is related in a very simple way to more-or-less well-separated quantal transitions, while birefringence is a complicated average over all transitions in the molecule.
TL;DR: The recent development of a wide range of physical methods for studying single crystal surfaces under carefully controlled conditions has revolutionized the prospects for obtaining fundamental information at the molecular level in the field of surface physics and chemistry.
Abstract: The recent development of a wide range of physical methods for studying single crystal surfaces under carefully controlled conditions has revolutionized the prospects for obtaining fundamental information at the molecular level in the field of surface physics and chemistry. It is generally recognized [1] that in order to make further substantial advances in this field, techniques must be developed which give detailed structural information on the interfacial region. A brief description of such techniques currently under development follows.