Energy Transfer in Monochromatically-Excited Hydrogen (B 1Σ u+). I. Excitation Processes, Electronic Quenching, and Vibrational Energy Transfer

Abstract

Excitation of HD molecules into specific vibrational and rotational levels of the B 1Σ u+ electronic state by absorption of the 1048 and 1066 Å argon resonance lines has been studied under various experimental conditions by observing the steady-state fluorescence spectra of the (B 1Σ u+→ X 1Σg+) Lyman bands. Strong excitation of the (v′ = 3, J′= 2), (v′ = 5 , J′=2), and (v′ = 6 , J′ = 5) levels was achieved. The HD (B 1Σ u+ → X 1Σg+) electronic fluorescence from v′=3 was found to be quenched by HD, 3He, 4He, and Ne with effective collision cross sections of 79, 8.8, 9.9, and 3.5 Å2 at 297°K. Vibrational energy transfer processes HD(B 1Σ u+ ; v′=3, J′) + M→ HD(B 1Σ u+; v′=2, J′ + Δ J′ ) + M+ Δ Ewere studied for the collision partners 3He, 4He, and Ne. Large effective cross sections of 0.89, 0.76, and 0.81 Å2 were found at 303°K. Rotationally-resolved spectra for Ne show that vibrational energy is transferred into both rotation and translation. All energetically accessible values of ΔJ′ were observed. On the average one-half of the vibrational energy was transferred into rotation.