Single crystal laser Raman spectroscopy

Abstract

The chemical implications of single crystal Raman spectroscopy by means of laser excitation are briefly outlined. Unambiguous assignments are presented for PdCl 2- 4 , PtCl 2- 4 , PtCl 2- 6 , PdCl 2- 6 , GeCl 2- 6 and TeCl 2- 6 species. Detailed scattering equations are applied to mercurous chloride. The vibrational spectra of cassiterite, anataseand rutile are discussed in terms of the factor group. Gallium trichloride and aluminium tribromide spectra are discussed from the viewpoint of a perturbed D 2h Raman tensor. The complex spectrum of molybdenum trioxide is interpreted in terms of a site-factor group analysis. Problems of birefringence, crystal imperfection, dichroism, the resonance Raman effect, twinning, enantiomorphism, internal reflexion and dependence of relative intensity on physical state are noted. The methods discussed are applied to the first-order spectra of centrosymmetric crystals and rely on the validity of the Raman tensor predictions resulting from factor group analysis.

Controllable Formation of (004)-Orientated Nb:TiO2 for High-Performance Transparent Conductive Oxide Thin Films with Tunable Near-Infrared Transmittance

“…The well-defined Raman spectra between 80 and 700 cm –1 are characteristic of the anatase phase for NTO thin films, as shown in Figure . All films show similar peaks appearing around 144, 197, 399, 513, and 639 cm –1 , which correspond to three Raman modes of anatase TiO 2 . − Raman experiments further confirm that NTO thin films do not exhibit any structural phase transition from anatase to rutile, and no NbO x phases are observed either. This is in good agreement with our XRD analysis.…”

Photodegradation of 1,2,4-Trichlorobenzene on Montmorillonite–TiO2 Nanocomposites

“…As X-ray diffraction did not provide conclusive information on the nature of titanium species existing in the solids, these were studied by Raman spectroscopy. The spectra ( Figure 2) showed that sample MTi1 was composed of both anatase and rutile phases, while sample MTi2 contained only anatase [29,30]. Considering that both samples were calcined under identical conditions, these results suggested that the crystallization of TiO 2 phases depended on the way the titanium precursor was reacted with montmorillonite.…”

Disulfide Bond Dihedral Angles from Raman Spectroscopy

“…In fact, Tobin (32) has cautioned that polarizabilities obtained from Raman experiments with crystals pertain to the crystal and not to the individual molecules. In general, only the frequencies (and not the intensities) can be relied on to reflect the Raman properties of the free molecule (33). Further, since the S-S stretch occurs at low frequency (about 500 cm-'), this internal mode of the molecule may couple with an overtone of a lattice mode in the crystal.…”