ABSTRACT
We calculate the susceptibility responsible for self-focusing in SF(6) in two parts, the v(3)-ladder contribution and the quasi-continuum contribution. Our v(3)-ladder vibrational model is a classical triply degenerate anharmonic oscillator in the Cartesian basis with the anharmonicity parameters chosen to be consistent with the latest spectroscopic analysis of the 3v(3)-overtone spectrum. The rotational structure is represented by a distribution of these oscillators in which the distribution is chosen to correspond to the spectrum of the v(3) fundamental. Using our previously published model, we find that the quasi-continuum contribution is much smaller than the v(3)-ladder contribution to the susceptibility and always decreases with increasing laser energy. We find that the v(3) ladder is entirely responsible for self-focusing in SF(6) . The susceptibility curves show qualitative agreement with the 300-K self-focusing data of Nowak and Ham [Opt. Lett. 6, 185 (1981)] at CO(2)P(28), P(20), and P(10) in SF(6). Calculations with a two-dimensional diffraction-propagation code show good quantitative agreement with the Nowak and Ham data at CO(2)P(20) and P(10).
ABSTRACT
Two recent detailed models of multiple-photon excitation in SF(6) are compared. By performing equivalent vibration-rotation calculations using the two different basis sets, we have found that the results are in complete agreement. Rotational effects in both cases completely overshadow the vibrational structure, making a triply degenerate anharmonic oscillator model sufficient for describing multiple-photon excitation in SF(6).
ABSTRACT
Single-photon transition moments for overtone states of triply degenerate modes of spherical-top molecules applicable to multiple-photon dynamics calculations are derived for zeroth- and first-order theories. In each case the total transition strength for excitation out of a given angular momentum state is in agreement with well-known results for the triply degenerate oscillator. In contrast with recently published results, this work shows that all strongly allowed multiple-photon pathways do occur.
