Spectrograph double

As early as 1940, Reitz used a double spectrograph with combined positive and negative dispersion for the reduction of stray light as he recorded Raman spectra of crystal powders on photographic plates. 

Por IR-Raman experiments, a mid-IR pump pulse from an OPA and a visible Raman probe pulse are used. The Raman probe is generated either by frequency doubling a solid-state laser which pumps the OPA [16], or by a two-colour OPA [39]. Transient anti-Stokes emission is detected with a monocliromator and photomultiplier [39], or a spectrograph and optical multichannel analyser [40]. 

The high performance of modem spectrographs means that low power lasers can be used as excitation sources. These are typically 10—100-mW devices which are air-cooled and can be operated from 117-V a-c lines. In the green, the Ar" (514.5-nm) laser remains the most popular but is being challenged by the smaller and more efficient frequency doubled Nd YAG (532-nm). In the nir, diode lasers (784-nm) and diode-pumped alexandrite... 

Spectrographically standardised substances 830 Spectrophotometer cells for, 664 data presentation, 665 double-beam, 667 layout of instruments, 666, 667 operation of, 672 radiation sources for, 664 single-beam, 666... 

A detachable monochromator (19) developed by Spex Industries, was another approach in minimizing stray light. It is a modified Czerny-Turner spectrograph which can be coupled to the exit slit of a double monochromator and function as a variable bandpass, variable frequency filter. This accessory, while providing the versatility of a triple monochromator, does not add much mechanical and optical complexity and can be removed when not wanted. 

D. T. Young, J. A. Marshall, J. L. Burch, T. L. Booker, A. G. Ghielmetti, and E. G. Shelley. A Double-Focusing Toroidal Mass Spectrograph for Energetic Plasmas. II Experimental Results, Nucl. Instr. and Meth., A258(1987) 304. 

Fig. 4.22. Mattauch-Herzog double-focusing mass spectrograph providing direction and momentum focusing of ions on a plane. [73] Reprinted from Ref. [1] with permission. American Association for the Advancement of Science, 1979.

Open-beam double-pass instruments using a retro-flector array to return the light beam back to the spectrograph are also in use (e.g., Mount, 1992 Mount and Harder, 1995 Harder et al., 1997a). Another variation is the use of a fast-scanning technique with pi-... 

Figure 3.6 Schematicofa double-focusing sector field mass spectrograph with Mattauch-Herzog geometry with a linear imaging curve (double focusing for ions of all masses simultaneously) modified field combination with 70°. In the mass spectrograph, photographic ion detection or focal plane array detectors are used for quasi-simultaneous detection of separated ion beams. (H. Kienitz (ed.), Massen-spektrometrie (1968), Verlag Chemie, Weinheim. Reproduced by permission of Wiley-VCH)...

Recently, Hieftje et al.15-16 equipped a small double-focusing mass spectrograph built in house with Mattauch-Herzog geometry with several ion sources (such as glow discharge, an inductively coupled plasma ion source or a microwave plasma torch) and a novel array detector for simultaneous ion detection. 

R. Robertson [62] examined the decomposition of nitroglycerine at temperatures from 90 to 135°C, using a carbon dioxide stream to remove volatile decomposition products. The concentration of nitrogen oxides in the jet of carbon dioxide was established spectrographically. He found in this way that nitroglycerine decomposed in a manner similar to that of fairly well stabilized nitrocellulose, but more rapidly. In the temperature range of 95—125°C, every 5° elevation of temperature doubled the decomposition rate in these conditions. 

Comparison with Sector Instruments. Modern double-focussing mass spectrometers have a long history of development, which was recently reviewed O) The instrument has evolved through a long series of complex and interweaving events beginning with the early experiments of J. J. Thomson (2) and the first mass spectrographs of... 

The basic experimental arrangement is shown in Figure 1. A Q-switched ruby pump laser is frequency doubled to pump a broadband dye laser with a piano-spherical cavity. The remaining ruby power and the dye pulse were then used for the non-linear spectroscopy experiments. Spectra were recorded on film or plates by means of a Spex Model 1701 spectrograph equipped with a camera. The smoothness of the dye output intensity with wavelength, which determines the sensitivity of the single-pulse spectra, varied from shot to shot and depended on the dye. 

Two measurements [31,10] were conducted at a low-inductance vacuum spark plasma and a tokamak plasma respectively. In both cases only the w line was reported. The first study used a double Johann spectrograph and characteristic K lines were used for calibration [31]. The energy of the w was 5.20558(55) keV or a 105 ppm result The second study [10] used a tokamak plasma and claimed an uncertainty of 40 ppm. Close lying Lyman series lines were used for calibration so this was a relative measurement chain assuming one-electron QED. Shorter wavelength calibration lines and helium-like resonances were observed in second order diffraction suggesting the significant systematic shifts discussed above. The third study [11] was a relative measurement to the w line and, as such, can not be compared to absolute measurements. 

Recently, Hieftje et equipped a small double-focusing mass spectrograph built in house... 

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