Far Infrared and Raman Spectra

The variation of the far-infrared and Raman spectra of zeolites, induced by the exchange of cations, clearly indicates that the cationic degrees of freedom manifest themselves in that frequency region where large-amplitude deforma-... 

The gas-phase Raman spectra of trimethylene imine and trimethylene imine-N-tf were studied later by Carreira et al.90 The transitions in the low-frequency region for trimethylene imine-N-d are shown in Fig. 4.21, and Table 4.13 summarizes the assignments of the transitions observed in the far infrared and Raman spectra. The... 

In the case of cyclobutane and cyclobutane-d8, the ratio of the A potential constants is calculated to be 1.4063 0.004, while the square of the ratio of the B potential constants is 1.367 0.0080 (T. B. Malloy and W. J. Lafferty, unpublished calculations). There is a small but significant discrepancy. The far-infrared and Raman spectra of five deu-terated species of trimethylene oxide (TMO) have been reported in an important series of papers by Wieser and his co-workers.24-26 In the case of this molecule, which has a low barrier of about 15 cm"r, the isotopic relations are found to fail totally. 

Irradiation of (305a) with M(CO)6 (M = Cr, Mo, W) in a molar ratio of 1 2 yields microcrystalline complexes [(305a)2 M(CO)4] M = Cr, W, and [(305a)3 Mo(CO)4] , n>2, which are insoluble in all organic solvents. Probably the complexes are polymeric. The structures were discussed on the basis of their mass, infrared, far infrared and Raman spectra. 

In the case of methanol, the gas phase dimer has not been observed experimentally, thus the configuration found in the crystal structure [31] is taken to be close to that expected for the free dimer at OK. Further, the far infrared and raman spectra are known only for the crystalline [49] state, and the symmetric stretch frequencies used here as guides are experimentally somewhat perturbed by crystal packing effects and thus are allowed to deviate somewhat from the observed values. The experimental dimerization data for methanol [20] is also not as well defined as it is for the carboxylic acids, and an average of several experimental values is used. 

Various ratio and distribution among the toughening zirconia polymorphs as result of the different sintering techniques could partially explain the obtained mechanical properties (Vickers hardness and fracture toughness by indentation). This assessment would be sustained by microstructural features analysis, XRD, far infrared and Raman spectra as follows. 

The effects of heating technique on the far infrared and Raman spectra were investigated. Additional bands development was observed on spectra as the crystal symmetry is lowered, and certain of these bands are highly sensitive to strain-induced distortions of the crystal lattice. 

In the gaseous state coupling of the vibrational transitions with the rotational degrees of freedom give rise to rotational-vibrational bands (Fig. 2.6-1 A). The structures of these bands characterize the shape of a molecule and its symmetry (see Sec. 2.7). Spectral lines in the far-infrared range and in low-frequency Raman spectra are due to pure, quantized rotations of the molecules. Infrared and Raman spectra of gases are discussed in detail in Secs. 4.3.1 and 4.3.2. 

The metal isotope technique has been used to assign the p(M—py) and /(MX) vibrations of Zn(py)2X2 and Ni(py)4X2. The former vibrations have been located in the 225-160 and 250-225 cm" regions, respectively, for the Zn(ll) and Ni(II) complexes. Figure 111-9 shows the infrared and Raman spectra of [ Zn(py)2CU) and its Zn analog. As expected from its C20 symmetry, two i (Zn—py) and two v ZtiC ) are metal-isotope sensitive. Far-infrared spectra of metal pyridine nitrate complexes, M(py)x(N03)y, have been reported. 

Progress in Infrared Spectroscopy, Vol. 1, H. A. Szymanski (editor). Plenum Press (1962). Proceedings of the fifth annual Infrared Spectroscopy Institute held in Canisius College, August 1961. Includes practical chapters on such topics as ultraviolet, far-infrared and Raman spectroscopy, as well as polymer spectra, for the industrial chemist. The question-and-answer section in the Appendix may be helpful in answering many of the beginner s basic questions. 

The purpose of this book is to provide a simple introduction to characteristic group frequencies so as to assist all who may need to interpret or examine infrared and Raman spectra. The characteristic absorptions of functional groups over the entire infrared region, including the far and near regions, are given in tables as well as being discussed and amplified in the text. 

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