Analysis of the molecular bands of D2H and H2D at 5600 Å

Abstract

Spectral simulation was used to analyze the molecular rovibrational bands of D 2 H and H 2 D at 5600Å.These bands were previously measured by the ion beam neutralization method. They were assigned to the electronic 3p 2 B 1 -2s 2 A 1 and vibrational (v − v ) = (0, 0, 0, −0, 0, 0) transitions. Least squares fits to the experimental line-positions were made to determine the asymmetric rotator constants A, B and C for the 2s 2 A 1 and 3p 2 B 1 v = 0 states of D 2 H and H 2 D, hitherto unknown. Lorentz line-profiles were assumed for the D 2 H and H 2 D rotational lines, whose widths are mainly governed by the lifetimes of the lower states. The bands at 5600Å were simulated and the 2s 2 A 1 state lifetimes were estimated to be σ ≥ 0.5 ± 0.2 ps for D 2 H and σ ≥ 0.4 ± 0.2 ps for H 2 D. Vibrational constants of D 3 and D 2 H in the 2s 2 A 1 states are determined from the positions of the 0-0 and 0-1 vibrational bands given in respective experimental spectra previously measured. For the first time the vibrational constants ω 1 and ω 2 of the 2s 2 A 1 state of H 2 D were estimated from the positions of the 0-0 and 0-1 band maxima. These vibrational constants are compared with the corresponding vibrational constants of their ions.