A Molecular Beam Study of the Selective Dissociation of SF₆: The Influence of Laser Wavelength and Energy

Abstract

Though an almost innumerable number of contributions to the understanding of the multiphoton excitation of SF₆ has already been published, the interest in this molecule seems undiminished. The dispute about the details of the excitation mechanism is far from being settled definitely. To-date it is, however, commonly accepted that the lowest lying energy levels are pumped coherently [1,2]. The anharmonicity compensating mechanism is supposed to be anhannonic splitting of excited vibrational states [3] and rotational compensation [4]. It is further believed that, beginning at approximately V = 4 [4], the energy levels become sufficiently dense to be regarded as a quasi-continuum. Further excitation in this regime, which is just incoherent single photon heating, finally leads to the dissociation of the molecule. The detailed mechanism of the transition between these two regimes is still subject to controversial debates. Currently theoreticians as well as experimentalists mainly concentrate on questions of energy migration within the molecule and on the applicability of the unimolecular RRKM formalism to these phenomena.