Vibrational predissociation of H5+.
Spirko, V.; Amano, T.; Kraemer, W. P.,
Journal of Chemical Physics, 124 244303 (2006)
The full nine-dimensional vibrational Hamiltonian for H-5(+) described in the literature [Kraemer , J. Mol. Spectrosc. 164, 500 (1994)] is adopted here for an approximate evaluation of the spectral linewidths of the observed H-H stretching modes of the H-5(+) ion and the corresponding modes of its D-5(+) isotopomer. In this approximation the high dimensionality of the original Hamiltonian is reduced to a three-dimensional model Hamiltonian which takes only the H-H stretching modes and the molecular dissociation mode into consideration assuming that they are adiabatically separable from the remaining modes. To make the calculations numerically feasible, the molecular degenerate ("skeletal") vibrations are assumed to take place in harmonic potentials, and the effect of the internal propeller rotation is completely disregarded. The linewidths calculated in this approximation are too small to explain the broad shapes of the observed spectral transitions. It can thus be argued that the failure to resolve rotational structure in the observed bands is mainly due to spectral congestion and only partly due to predissociation of the H-5(+) cluster.