Lifetimes and collisions in KH, A 1Σ+, v′ = 5–22

Abstract

KH obtained in a high frequency discharge in K+H₂ is selectively excited by a pulsed dye laser to A ¹Σ⁺, v′ = 5–22, J′ = 8 or 9. The radiative lifetimes are measured. They decrease slowly from v′ = 5 (64 ns) to v′ = 19 (53 ns) and rapidly at v′ = 22 (34 ns). Rotational transfer cross sections by collisions with H₂ increase from v′ = 5 (41 Ų) to v′ = 19 (92 Ų) as do the electric dipole moments in the levels. The collision with the electrons of the discharge provide rotational transfers where the ΔJ′ = ±1 transitions are the greatest and vibrational transfers Δv′ = ±1, ±2, where the ΔJ′ = 0 transitions are small. These results are to be expected in polar molecules where the interaction of the electron with the permanent dipole moment of the molecule is predominant.