Publication
Reference
Lowen H.~W., Bier K.~D., Jodl H.~J. (1990). Vibron-phonon excitations in the molecular crystals N$_2$, O$_2$ and CO by Fourier transform infrared and Raman studies. J. Chem. Phys., 93, 8565 - 8575.
Names
  • H.~W. Lowen
  • K.~D. Bier
  • H.~J. Jodl
Article and keywords
Title
Vibron-phonon excitations in the molecular crystals N$_2$, O$_2$ and CO by Fourier transform infrared and Raman studies
Abstract
The influence of temperature on the vibron–phonon combination band in the Raman and infrared (ir) spectra of the N$_2$ and O$_2$ molecular crystals supports the possibility of an assignment of the main features in the sideband to strong contributions from translational and librational phonons in points of high symmetry in the reciprocal lattices. The temperature behavior in Raman and ir sideband spectra in α-N$_2$ is attributed to distinct anharmonicities in the isotropic and anisotropic parts of the potential and to different coupling mechanisms, resulting in a librational and translational weighted one-phonon density of states (DOS). In contrast, such an interpretation is not feasible for the poorly structured CO sideband, although the crystal structures of CO and N$_2$ are nearly identical. The difference is attributed to strong anharmonicities and the presence of a weak dipole moment in the former, which introduces strong lattice mode coupling. Crossing the α–β phase transition has marked effects on the sidebands (shape, intensity) in both N$_2$ and O$_2$ crystals, which reflects the orientational disorder in the β phase of the former and the importance of the change in magnetic interactions in the latter. For both molecular crystals, the vibron–phonon coupling to the electromagnetic field is stronger in the ir than in the Raman spectra and seems predominantly due to electrical anharmonicities.
Keywords
spectroscopy, transmission spectra, Raman spectra, Mid-IR, phonons, band position, band vibration mode, phase change, temperature, ices, molecular solids, O2, N2
Content
spectral data, band list data, experimental physics
Year
1990
Journal
Journal of Chemical Physics
Volume
93
Pages
8565 - 8575
Document type
article
Publication state
published
Doi
10.1063/1.459294
Identifiers