Laser-induced fluorescence ofHg2H1uexcimer molecules

Abstract

Vibrational levels of the H$1_u$ state in ${\mathrm{Hg}}_2$ excimer molecules, correlated with the 6? sup 1 P sub 1— atomic state, were selectively populated by stepwise excitation using the metastable A$0_g^{\pm }$ states for the intermediate step, and the fluorescence emitted in the H$1_u$→X$0_g^{+}$ bound-free decay was recorded with a spectrometer and a transient digitizer. The uv fluorescence bands, emitted in the decay of several upper-state vibrational levels with v’ ranging from 0 to 5, were centered near 1994 Å and consisted of well-resolved Condon internal diffraction patterns corresponding to appropriate upper-state vibrational wave functions. The energy separation between the A$0_g^{\pm }$ and H$1_u$ potential minima was determined and an estimate was made of the vibrational frequency ${\omega }_e$ of the H$1_u$ state. Much weaker excitation of the H$1_u$ state was also effected from the metastable B$1_g$ state, which allowed the energy separation between the B$1_g$ and A$0_g^{\pm }$ potential minima to be determined experimentally.