Publication
Names
  • Roberto Bini
Title
High-resolution infrared study of the translational lattice modes in α-N$_2$ single crystals
Abstract
The analysis of the far infrared spectrum of thin high quality α-N$_2$ single crystals as a function of temperature was carried out by high resolution Fourier-transform infrared spectroscopy. The bandwidths at T=8 K of the two translational modes, correlated to the two-phonon density of states, are considerably smaller than the Raman active modes. This result can be interpreted on the basis of a lower anharmonicity of the translations with respect to the librational modes. The α-N$_2$ is the first molecular crystal where such difference is found. The evolution of the T$^(1)_u$ linewidth was studied until the α-β phase transition. The relaxation of this mode is essentially dominated by fourth-order decay processes. The study of the frequency shifts of both infrared phonons allowed the contributions relative to different orders of the anharmonic potential to be separated. Finally a careful analysis of the relative intensities of the two phonons was carried out in the α phase.
Keywords
spectroscopy, transmission spectra, far-IR, band position, band width, band vibration mode, temperature, ices, molecular solids, N2
Content
spectral data, band list data, experimental physics
Year
1996
Journal
Journal of Chemical Physics
Volume
104
Number
12
Pages
4365 - 4370
Document type
article
Publication state
published