The excitation spectrum for the photoassociation (bound←free absorption) of thermalized pairs of Kr(4p6 1S0) and F(2p5 2P) atoms in Kr/F2 gas mixtures at 300 K has been recorded in the ultraviolet (208≤λ≤250 nm). By photodissociating F2 in the presence of Kr and subsequently photoexciting Kr-F collision pairs in the ground state thermal continuum with tunable laser radiation, deeply modulated Franck-Condon structure associated with bound←free transitions terminating on the lowest 26 vibrational levels of the B 2Σ ion pair state of the KrF molecule was observed. Since the KrF ground state interaction potential is repulsive, photoassociation occurs in a narrow (ΔR≈0.7 Å) Franck-Condon region and structural information regarding the upper and lower state potentials, as well as the dependence of the electronic transition moment on internuclear separation, can be extracted from the spectrum. The Kr-F system is presented here as an example of the effectiveness of photoassociation as a tool with which one can determine the chemical, structural and optical properties of small excimer molecules that are otherwise difficult to access experimentally.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry