Hydrogen stretching mode

Frequencies of the hydrogen stretching mode for H° at the bond-center site have been obtained from cluster calculations. Estreicher (1987) found the potential profile for displacements of H along the bond to be U-shaped and flat for small displacements (—0.1 A). Consequently, he found a very low vibrational frequency for such displacements ( that of single Si—H bonds). Other studies of the stretching mode have found 784 cm-1 (Deak et al., 1988) and 800 cm-1 (DeLeo et al., 1988). 

Abstract—A brief review is given of earlier low temperature studies (4° 20°K of the hydrogen stretching mode of H bonded species. Evidence for sharpening of band structure is quoted (e.g., acetyl glycine, hydrate salts). In contrast are studies for which the band breadth has been found to be virtually independent of tsmoerature (H80 CH3OH). 

For H4Ru4(CO)i2, a larger number of fundamental absorptions are expected, five Raman-active hydrogen stretching modes (Ai, B1, B2, and 2E) and three ir-active modes (B2 and 2E) coincident with the Raman bands. As mentioned above, the observed spectra consist of only two bands in both the Raman and ir,... 

If no absorption bands are present in the functional group region, with the exception of those arising from carbon-hydrogen stretching modes, consider the possibilities of ethers, alkyl halides, sulphur compounds, tertiary amines and nitro compounds as detailed in the sections below. 

The splitting of the fundamental vibration, essentially a hydrogen-stretching mode, has also been observed, being about 1.6 cm (Dennison and Hardy, Phys. Rev. 1932, 39, 938). 

It Is a familiar observation in vibrational spectroscopy that a hydrogen bending or deformation vibration has a fundamental frequency approximately half that of the hydrogen stretching modes. It may then happen that cubic enharmonic interaction terms in the potential couple the stretching mode to the overtone of the bending mode. The terms concerned will be of the type... 

Near-infrared spectra can be explained by assigning the bands to overtones and to combination frequencies of the hydrogen stretching modes. 

The infrared spectra of benzene and its derivatives show characteristic bands in three regions. The first is at 3030 cm for the phenyl-hydrogen stretching mode. The second ranges from 1500 to 2000 cm and includes aromatic ring C-C stretching vibrations. Finally, a useful set of bands due to C-H out-of-plane bending motions is found between 650 and 1000 cm ... 

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