Raman spectra complexes

IR and Raman spectroscopy have been commonly used and, for example, the effects of pressure on the Raman spectrum of a zinc compound with a N2C12 coordination sphere around the metal, have been investigated.28 IR spectroscopy has been utilized in studies of the hydration of zinc in aqueous solution and in the hydrated perchlorate salt.29 Gas phase chemistry of zinc complexes has been studied with some gas phase electron diffraction structures including amide and dithiocarbamate compounds.30-32... 

The ground state spectrum in Figure 5 exhibits the typical features of the Raman spectrum of a bipyridine complex (40,51,52). Seven relatively intense peaks dominate the spectrum. These may be approximately described as the seven symmetric C-C and C-N stretches expected of bipyridine in any point group wherein the two pyridine rings are related by a symmetry element. 

In Chapter 8, Stavola and Pearton discuss the local vibrational modes of complexes in Si that contain hydrogen or deuterium. They also show how one can use applied stress and polarized light to determine the symmetry of the defects. In the case of the B-H complex, the bond-center location of H is confirmed by vibrational and other measurements, although there are some remaining questions on the stress dependence of the Raman spectrum. The motion of H in different acceptor-H complexes is discussed for the Be-H complex, the H can tunnel between bond-center sites, while for B-H the H must overcome a 0.2 eV barrier to move between equivalent sites about the B. In the case of the H-donor complexes, instead of bonding directly to the donor, H is in the antibonding site beyond the Si atom nearest to the donor. The main experimental evidence for this is that nearly the same vibrational frequency is obtained for the different donor atoms. There is also a discussion of the vibrational modes of H tied to crystal defects such as those introduced by implantation. The relationship of the experimental results to recent theoretical studies is discussed throughout. 

Substitutional B in Si has a triply degenerate local mode that is observed in both IR absorption and Raman spectra. There are two naturally occur-ing isotopes, nB (82.2%) and 10B (18.8%), with distinct vibrational bands near 623 and 646 cm-1, respectively (Newman, 1969). Changes in the Raman spectrum of the B local mode upon passivation by H or D have been studied (Stutzmann, 1987 Stutzmann and Herrero, 1988a,b Herrero and Stutzmann, 1988a). Spectra are shown in Fig. 6 for samples of B doped Si that are unpassivated and passivated by H and D. Upon passivation, the vibrations due to isolated B are reduced in intensity and new features appear at 652 and 680 cm-1 independent of whether the B is complexed with Hor D. 

The behavior of the Raman spectrum under stress of the stretching vibration of the B—H complex has been reported recently by Stutzmann and Herrero (1988a,b) and by Herrero and Stutzmann (1988a,b). Spectra measured at 100 K are shown in Fig. 18 for several values of [100] stress. The dependence of the mode frequency on [100] and [112] stress is shown in Fig. 19. There were stress induced splittings observed for [100], [112], and [110] stress directions. For the [111] stress direction the line broadened for low stresses but did not split. Further, the stress-split component that shifts upward in frequency as the stress is increased decreases in intensity. 

Strong, complex feature at 618 cm-1 in resonance Raman spectrum when excited with 442 nm radiation... 

TeF4 and SbF5 form a 1 1 adduct (16). The Raman spectrum of this complex in the molten state has been recorded (65). It was not possible, however, to decide between the most plausible alternatives, i.e., ionization into the ions (TeF3)+ and (SbF ), or the formation of a fluorine-bridged structure F3TeFSbF5. 

For this purpose, we cleaned the lower than 1000 cm and higher than 1500 cm" areas by subtracting the Raman spectrum of the solvent (see Analysis Methods) in order to make some possible modifications of the sugar-phosphate part of DNA upon complexation conspicuous. Furthermore, we could expect to refine the nature of the weak interactions of SOAz with DNA b s by observing the low frequencies characteristic of these bases. 

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