Spectrometers spectrograph

The design and use of spectrographs or spectrometers involves a compromise between resolution—how close in wavelength two lines can be and still be seen as separate—and sensitivity—how weak a light can be observed or how... 

In 1951Castaing8 published results to show that an electron microscope could be converted into a useful x-ray emission spectrograph for point-to-point exploration on a micron scale. The conversion consisted mainly in adding a second electrostatic lens to obtain a narrower electron beam for the excitation of an x-ray spectrum, and adding an external spectrometer for analysis of the spectrum and measurement of analytical-line intensity. Outstanding features of the technique were the small size of sample (1 g cube, or thereabouts) and the absence of pronounced absorption and enhancement effects, which, of course, is characteristic of electron excitation (7.10). Castaing8 gives remarkable quantitative results for copper alloys the results in parentheses are the quotients... 

The apparatus as modified for x-ray emission spectrograph is also shown in Figure 11-1. The proportional counter may be used alone (pulse-height analysis Section 2.13) or a curved-crystal spectrometer can be employed to achieve better resolution. Analytical results were comparable to those quoted above, but localization of the area analyzed was considerably less sharp than the micron-diameter spot achieved in differential absorptiometry. 

It is interesting that the very broad, so-called spin-allowed transitions, like most of those in Fig. 2-1, were not actually recognized as such until the 1950 s. This was because of the characteristics of the spectrograph rather than the spectrometer. 

Since modern FTIR spectrometers can operate in a rapid scan mode with approximately 50 ms time resolution, TRIR experiments in the millisecond time regime are readily available. Recent advances in ultra-rapid scanning FTIR spectroscopy have improved the obtainable time resolution to 5 ms. Alternatively, experiments can be performed at time resolutions on the order of 1-10 ms with the planar array IR technique, which utilizes a spectrograph for wavelength dispersion and an IR focal plane detector for simultaneous detection of multiple wavelengths. ... 

The earlier stable isotope dilution mass spectrographic work was accomplished with a thermal ion mass spectrometer which had been specifically designed for isotope abundance measurements. However, Leipziger [829] demonstrated that the spark source mass spectrometer could also be used satisfactorily for this purpose. Although it did not possess the excellent precision of the thermal unit, Paulsen and coworkers [830] pointed out that it did have a number of important advantages. 

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