Spectroscopic techniques monochromators

Most of the frequency-domain light scattering data of supercooled liquids are obtained by the two spectroscopic techniques discussed above. As an example, Fig. 4 shows partial spectra of glycerol obtained with a grating monochromator and a tandem FPI, which are combined into a single composite spectrum that extends from 400MHz some bve decades up in frequency. We will therefore be mostly concerned with these techniques in the following. 

The application of X-ray photoelectron spectroscopy (XPS) [1, 20-22], has considerably extended the possibilities. The main advantage of XPS is that, in contrast to the spectroscopic techniques mentioned above, it can in principle provide information on all valence levels. A drawback is that the energy resolution of spectra of solid samples is low, especially when a non-monochromated X-ray source (A1 Ka radiation with a natural width of 1 eV) is used. 

In summary, there seems to be no fluorimetric alternative to excel low-temperature techniques in analytical information throughput if chemical separations are to be avoided. Massive use in the environmental field has so far been restricted by the need to use fairly sophisticated devices such as high-resolution monochromators, cryostats, and, perhaps, dye lasers. On the other hand, a number of commercially available spectrofluorimeters provide inadequate spectral resolution for use in low-temperature spectroscopic techniques. However, given the high selectivity of such techniques, their use in the characterization of complex environmental samples will continue to grow in the foreseeable future. 

In contrast to the well-known difficulties of traditionally applied quantitative IR spectroscopy of mixtures in solid (powdered) samples, the near-infrared reflectance analysis (NIRA) technique [32] has gained importance over the last decade and can now be implemented on a variety of commercially available Instruments In a number of applications to Industrial, agricultural and pharmaceutical analyses. Both the NIRA instruments equipped with grating monochromators and those fitted with filter systems feature built—In microprocessors with software suited to the Intrinsic characteristics of this spectroscopic alternative. Filter Instruments generate raw optical data for only a few wave-... 

The contents of Chap. 4, which covers spectroscopic instrumentation and its application to wavelength and intensity measurements, are essential for the experimental realization of laser spectroscopy. Although spectrographs and monochromators, which played a major rule in classical spectroscopy, may be abandoned for many experiments in laser spectroscopy, there are still numerous applications where these instruments are indispensible. Of major importance for laser spectroscopists are the different kinds of interferometers. They are used not only in laser resonators to realize single-mode operation, but also for line-profile measurements of spectral lines and for very precise wavelength measurements. Since the determination of wavelength is a central problem in spectroscopy, a whole section discusses some modern techniques for precise wavelength measurements and their accuracy. 

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