Flash spectroscopy with mercury resonance radiation. Part 5.—Formation and relaxation of Hg(63P0)

Abstract

Relaxation rates of Hg(6³P₀) were investigated following black-body flash excitation and also following monochromatic flash excitation with the 2537 Å resonance line. In an excess of N₂ with black-body excitation, the Hg(6³P₀) exhibited anomalously slow decay profiles which were attributed to the production of N₂A³∑⁺_u by energy transfer from highly excited states of mercury. Accurate deactivation rates of Hg(6³P₀) by H₂, NO, CO, O₂, CO₂, N₂O, CH₄, C₂H₆, C₃H₈, C₂H₄ and NH₃ were measured by monitoring the weak 2537 Å afterglow following monochromatic excitation with very low flash energies.

Quantum yields for the Hg(6³P_{1 → 0}) relaxation were also measured in each of the gases, by comparing the [Hg(6³P₀)] with that formed in N₂ with the same fractional quenching of Hg(6³P₁).

The nature and symmetry of the intermediate complexes in Hg-photosensitised reactions were formulated with qualitative molecular orbital considerations. It was suggested that the relative stability of Hg(6³P₀) with respect to collisional deactivation is generally due simply to the decreased internal energy.