Tables of molecular vibrational frequencies

Abstract

Fundamental vibrational frequencies of 109 molecular forms of 38 polyatomic chain molecules consisting of the CH3, CD3, CH2 CD2, CHD, O, and S groups are given as an extension of tables of molecular vibrational frequencies published in the NSRDS-NBS publication series and in this journal. On preparing the tables in this part, an approach, different from that in the previous parts, based on the calculations of normal vibration frequencies was adopted. A set of force constants which explains all the frequencies of small molecules for which the assignments had been established was obtained and then the frequencies of larger molecules was calculated and compared with the frequencies observed in the infrared and Raman spectra. The tables provide a convenient source of information for those who require vibrational energy levels and related properties in molecular spectroscopy, thermodynamics, analytical chemistry, and other fields of physics and chemistry.

Coke formation during the methanol conversion to olefins in zeolites studied by UV Raman spectroscopy

“…It can be seen À1 is assigned to the C±O stretching vibration, and the band at 1467 cm À1 is a deformation mode of the CH 3 group. The two bands at 2849 and 2954 cm À1 can be attributed to symmetric and asymmetric stretching vibrations of CH 3 group [23]. All these bands except for the one at 1023 cm À1 are shifted to higher wave numbers as compared to those of pure liquid methanol, indicating that methoxyl groups are formed on the zeolite surface [24,25].…”

An infrared spectroscopic and temperature-programmed desorption study of methyl iodide hydrogenation on Pd()

“…This therefore indicates that these features are due to molecular methyl iodide on the surface. These peaks can be straightforwardly assigned by comparison with gas-phase methyl iodide [24] and the assignments are displayed in Table 1. Note, however, that the relative intensities of the multilayer 1243-and 884-cm À1 features vary with exposure.…”

A comprehensive and comparative study of elastic electron scattering from OCS and CS2 in the energy region from 1.2 to 200 eV

“…The vibrational fundamental modes, whose energy spacing in both OCS (ν 1 : 107 meV, ν 2 : 64.5 meV, ν 3 : 256 meV) and CS 2 (ν 1 : 81 meV, ν 2 : 49 meV, ν 3 : 190 meV) 50 means they can of course be excited in both apparatus, might also make some contribution (together with rotational excitation) to the elastic scattering intensity. With the present energy resolution these modes can only be partially resolved in the low energy (high resolution) apparatus, and rotational effects cannot be resolved at all.…”