Single-crystal spectra

Spectroscopic analysis of Pu5+ and Pu6+ halides is in its initial stages. No low-temperature single-crystal spectra have been reported. A 25°C mull spectrum of the compound Rb2PuF7 was described earlier (37), and is now supplemented by the results for CsPuFg (31) PuF gas-phase spectra have been reported by several different groups at ANL (38-39). 

Most of the information content from ESR spectra of organometallic radicals and coordination complexes comes from dilute single-crystal spectra or frozen solution spectra. Nonetheless, there are some bits of information and applications that come uniquely from isotropic spectra, and we discuss those aspects in this chapter. 

Intensity dependence on rhombic distortion at Fe(IIl), 36 226-229 NIR CT bands, 36 217-220 polarized single-crystal spectra, 36 221-222... 

IV, EXPERIMENTAL SPECTRA AND THEIR ANALYSIS A. Single-Crystal Spectra... 

CsNiCl3-type). Table 6 summarizes results on electronic spectra. The three spin-allowed transitions are usually observed and extensive vibrational contribution has been observed in single crystal spectra.120,121 Intense spin-forbidden transitions may also be observed122 due to exchange interactions in the solid phase. The diiodide123,124 and the complex halides121 show trigonal distortion. 

The results observed for ethyne adsorbed on single-crystal surfaces are not easy to relate to those observed for ethyne on the finely divided metals. This is because the more readily interpreted spectra of the species on the flat surfaces occur at low temperature, whereas, with one exception, the spectra of the species on the metal particles have been obtained at room temperature. There is, however, one common finding, namely, that ethyli-dyne is frequently found in single-crystal spectra near 300 K and that this species has been found at room temperature on oxide-supported catalysts of Ni, Pd, and Rh. 

The tetrahedral structures XHj are still extensively investigated, and the factor-group splittings reported, although the attention is now also focussed on the single-crystal spectra. 

Remember that when single crystal spectra are studied a variety of weak lines due to forbidden transitions may be detected in addition to the main features. Also, radicals containing magnetic isotopes of low abundance, such as 13C, may contribute weak bands. 

Fig. 6. The temperature evolution of the single crystal spectra (//llZ-axis) of Cs2Zn099 Cu0.oi(ZrF6)2 6H20.

The peculiarities of the X-band spectra are more pronounced in the Q-band experiment. The corresponding powder spectra are shown in Fig. 8. (We have also measured single crystals spectra but there were some difficulties in signal detection at intermediate temperatures, between 35 and 50 K.) The Q-band temperature dependence of the line widths at T < 40 K is included in Fig. 7. 

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