			15min:

THE ORIGIN OF THE Ar cdots

I₂ B - X CONTINUUM EXCITATION SIGNAL BELOW AND ABOVE THE I₂( B ) DISSOCIATION LIMIT: BOUND-FREE TRANSITIONS OF THE LINEAR COMPLEX .

JOSHUA P. DARR, JOHN J. GLENNON AND RICHARD A. LOOMIS, Department of Chemistry, Washington University, One Brookings Drive, CB 1134, Saint Louis, MO 63130.

Discrete features associated with transitions of both the T-shaped and linear Ar cdots I₂( X , v ''=0) complexes are observed in laser-induced fluorescence and action spectroscopy experiments performed throughout the I₂ B - X electronic region. The binding energy of the linear conformer is directly measured to be 250(2) cm^-1, 10 to 15 cm^-1 greater than that of the T-shaped conformer. Continuum signals are observed in the spectra that continue to energies well above the I₂( B ) dissociation limit. Our results indicate that the continuum signals can be attributed to transitions of the linear Ar cdots I₂( X , v ''=0) complex to the inner, repulsive walls of many Ar + I₂( B , v ') intermolecular potentials. The excited state complexes are thus very short lived and undergo direct dissociation into Ar + I₂( B , v ') products. There is no evidence for the previously proposed one-atom caging mechanism.