Manifestation of chaotic nuclear dynamics of highly excited polyatomic molecules in time-resolved electron diffraction data
by Ischenko, A. A.; Schafer, L.; Ewbank, J. D.
The effects of chaotic nuclear motion on time-resolved electron diffraction data recorded of vibrationally highly excited polyatomic molecules are investigated. For this purpose the time-dependent scattering intensities are expressed directly in terms of the joint phase space probability density in the form of the Wigner function. A simple semiclassical procedure is described that allows one to obtain the scattering intensities for polyatomic molecules in a state of chaotic nuclear motion using internuclear pair potentials. Model calculations show that electron diffraction intensities of molecules in a state of chaotic motion are clearly different from intensities obtained for systems in a state of regular nuclear motion. The procedure was applied to analyze electron diffraction data of sulfur hexafluoride, SF6, recorded in the temperature range from 650 K, the spectroscopically determined beginning of the quasi-continuum, up to 773 K. The analysis shows that, in this temperature range, the molecule exists in a state of regular nuclear motion. This result is remarkable because it indicates that the appearance of the quasi-continuum does not necessarily indicate the onset of chaotic nuclear motion.
- Journal
- Journal of Physical Chemistry A
- Volume
- 102
- Issue
- 37
- Year
- 1998
- Start Page
- 7329-7332
- URL
- https://dx.doi.org/10.1021/jp9820931
- ISBN/ISSN
- 1520-5215; 1089-5639
- DOI
- 10.1021/jp9820931