Overtone spectroscopy of H2 D+ and D2 H+ using laser induced reactions

The method of laser induced reaction is used to obtain high-resolution IR spectra of H2 D+ and D2 H+ in collision with n- H2 at a nominal temperature of 17 K. For this purpose three cw-laser systems have been coupled to a 22-pole ion trap apparatus, two commercial diode laser systems in the ranges of 6100-6600 cm-1 and 6760-7300 cm-1, respectively, and a high-power optical parametric oscillator tunable in the range of 2600-3200 cm-1. In total, 27 new overtone and combination transitions have been detected for H2 D+ and D2 H+, as well as a weak line in the 1 vibrational band of H2 D+ (220 101) at 3164.118 cm-1. The line positions are compared to high accuracy ab initio calculations, showing small but mode-dependent differences, being largest for three vibrational quanta in the 2 symmetric bending of H2 D+. Within the experimental accuracy, the relative values of the ab initio predicted Einstein B coefficients are confirmed. © 2007 American Institute of Physics.