The scattering of Hg(63P2) by CO, N2 and CO2

Abstract

The differential scattering pattern of a thermal beam of Hg(6³P₂) from CO, N₂ and CO₂ has been measured from 10° to 160°(CM). Pronounced and regular oscillations are observed over the whole angular range in each system. However, the envelope is not that of purely elastic scattering, the χ^4/3 sin X^I(χ) plot showing an almost monotonic decrease over the whole angular range. The spacing of the oscillations indicates a deflection function with an unusually broad bowl, interfering branches being 3 Å apart. Two models are put forward; both include partial adsorption of the wave front and the operation of two potentials. Detailed fitting of one model shows that a highly attractive long range potential (well depth ≈ 10 kT) is needed, but although the interference structure is well reproduced, the necessary range of the optical potential is not consistent with known quenching cross sections. A second model is given in outline and involves an avoided crossing around 8 Å producing a rapid steepening of the potential gradient at that point. Quenching begins at impact parameters ∼ 7 Å thus indicating a very large quenching cross section unless a rather sharply peaked adsorption function is postulated with a width of only ∼1 Å to give the known values of σ_qu.