COLLISION-INDUCED ABSORPTION IN MERCURY-RARE-GAS COLLISIONS

The far-wing excitation and probe technique is applied to observe quas imolecular absorption bands on the blue side of the Hg 6 S-1(0)-6 P-3( 2) atomic line for the Hg-Ar, Hg-Kr, and Hg-Xe mixtures. It is found t hat the excitation of this band is followed predominantly by a rapid e lastic half-collision scattering on the excited state potential yieldi ng the nascent product state Hg(P-3(2)) This gives direct evidence of the assignment of the absorption to the c (3)1-->X O-1 collision induc ed dipole transition of the Hg-rare-gas quasimolecules. A chance of no nadiabatic transition from the c state is negligibly small compared to the elastic scattering. Analytical procedures are presented to deduce the c-X transition dipole moment from the relevant potential energy c urves by making use of the Hund's coupling schemes of the molecular el ectronic states. The c-X transition dipole moment is estimated as a fu nction of the internuclear distance and is incorporated into the analy sis of the observed band profiles. The potential energy curves of the c, A O-3(+), and B (3)1 states an also estimated from the analysis for HE-Ar and Hg-Kr. The Hg-Xe system shows a small undulation in the c-- >X band suggesting that it involves a satellite structure due to an ex tremum of the c-X difference potential. (C) 1998 American Institute of Physics.