Structure crystal vibrations

Weishaupt, M. and Strahle, J. (1976) Crystal structure and vibrational spectrum of tetraamminegold(III) nitrate. Zeitschrijifur Naturforschung, B31, 554-557. 

The results of a vibrational spectroscopic study of the SO2 complexes [RuX(S02)(NH3)4]" (X = Cl, Br) and [Ru(H20)(S02)NH3)4] + have been reported the j/(sym) and j/(asym) modes of the 5 -bound SO2 ligand come at lower frequencies than those of the free molecule. The ammonium salt of the sulfito complex tra 5-[Ru(S03-5)2(NH3)4] 4H20 has been structurally characterized. Although the crystals are stable when retained in the mother liquor, the isolated compound is only stable at 298 K for several days. Relationships between the structural and vibrational spectroscopic data are discussed. ... 

Spectroscopic (MS, NMR, IR) studies of quinoxalines were conducted . The structure and vibrational spectra of 2,3-bis(2-pyridyl)quinoxaline (bpq) and 2(A -methylpyridyl)-3-pyridylquinoxaline (meppq) useful for building blocks for dendrimers were measured by crystal X-ray diffraction and IR spectral experiments, respectively <2002JMT(589/90)301>. Those results were compared with ones calculated from the ab initio Hartee-Fock and the hybrid density functional methods. 

But if we examine the localized near the donor or the acceptor crystal vibrations or intra-molecular vibrations, the electron transition may induce much larger changes in such modes. It may be the substantial shifts of the equilibrium positions, the frequencies, or at last, the change of the set of normal modes due to violation of the space structure of the centers. The local vibrations at electron transitions between the atomic centers in the polar medium are the oscillations of the rigid solvation spheres near the centers. Such vibrations are denoted by the inner-sphere vibrations in contrast to the outer-sphere vibrations of the medium. The expressions for the rate constant cited above are based on the smallness of the shift of the equilibrium position or the frequency in each mode (see Eqs. (11) and (13)). They may be useless for the case of local vibrations that are, as a rule, high-frequency ones. The general formal approach to the description of the electron transitions in such systems based on the method of density function was developed by Kubo and Toyozawa [7] within the bounds of the conception of the harmonic vibrations in the initial and final states. 

The strong dependence of the layer structure on the nature of the contacting electrolyte has been further investigated by using the electrochemical quartz crystal microbalance (EQCM). As discussed above in Chapter 3, this technique is based on the measurement of the frequency with which a coated quartz crystal vibrates, and this frequency can then be related to the mass of this crystal provided that the material attached to the surface is rigid. In this way, the changes that occur in thin films as a result of redox processes can be monitored. 

Addition of CO to Ir(S03F)3 in HS03F results in the quantitative formation of Ir(C0)3(S03F)3 [139], Raman, infrared and 19F NMR spectroscopy indicate the presence of the mer- and /ac-isomers in solution, however, in the solid state, when solvent removal was rapid, it was established by an X-ray structure and vibrational spectroscopy that only the mer-Ir(C0)3(S03F)3 isomer crystallized. 

The least expensive approach is quasiharmonic lattice dynamics. The quasiharmonic approximation assumes that the free energy of a crystal can be written as the sum of a static contribution and a vibrational contribution. For periodic structures, this vibrational contribution is given by... 

Fig. 9. Structures of vibrational spectra in impure crystals, (a) represents impurities whose electronic states (e, e, ...) are uncoupled from the vibrations of the crystal. The phonon-spectra are superimposed on the eletron-ic levels (shaded area). Resonance (cor) or localised (coi) levels may appear, (b) If the impurity states are coupled to local vibrations, vibronic levels (v, v, .. .) appear whose spacings are generally much closer than for the electronic levels in (a). The superimposed phonon structures will fill in the energy range...

Matthew Marcus (center) received his PhD. in 1978from Harvard and joined Bell laboratories the same year. At Bell Labs, he worked on a variety of problems in materials science, with an emphasis on structure. Some of these problems include the structure of the liquid crystal blue phase, the precipitation kinetics of in Al films (probed by EXAFS), the relation between local structure and luminescence of Er in silica and silicon, and the structure and vibrations of nanoparticles of Au and CdSe. His contributions to EXAFS technique include methods for preparing samples and improved methods for fitting sets of data taken at different temperatures. In 1998, he left Bell Labs to work for KLA-Tencor, helping develop a new kind of PEEM-related electron microscope for wafer inspection. In 2001 he took on the position of Beamline Scientist at the Advanced Light Source, where he collaborates on environmental and materials problems using an X-ray microprobe. 

The process can be stimulated by vibrationally excited H2 molecules through their surface dissociation and diffusion of H atoms into the crystal structure. The process can be considered to be gasification of oxygen from the crystal structure by vibrationally excited hydrogen (Legasov et al., 1978c). Metal reduction starts from the surface. The front of metal formation propagates from the surface into the solid body. The depth of the reduction layer is limited by the recombination of H atoms ... 

Hayes, W., 1974, Crystals with the Fluorite Structure - Electronic, Vibrational and Defect Properties (Clarendon Press, Oxford). 

Theoretical calculations on the structure and vibrational spectra of [H(H20) ]" typically refer to free, isolated entities consequently, the results can be compared only with those of gas phase experiments, although simulated electrostatic effects of a crystal environment have been included for an isolated HjO" ion . 

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