Room temperature absorption spectroscopy of GeH2 near 585 nm

The absorption spectrum of the germylene radical produced in a continuous flow discharge of germane diluted in argon has been recorded in the 17 090–17 135 cm−1 region. This range corresponds to the central part of the Ã1B1(0, 1, 0)−X̃1A1(0, 0, 0) rovibronic transition, which has been analysed for the first time. The spectrum was measured by Intracavity Laser Absorption Spectroscopy with an equivalent pathlength of 15 km. The experimental resolution and wavenumber accuracy are of the order of 0.06 and 0.015 cm−1, respectively. Each rovibronic absorption is made up of five lines corresponding to the five germanium isotopomers appearing in a natural abundance sample. We have assigned around 25 transitions for each species, from which the rotational constants of the excited state and the band origin of the transition have been calculated. The equilibrium structure of the excited electronic state has been estimated with the help of ab initio data for some vib-rotational parameters. Good agreement is found with previous ab initio determinations of this structure.