Laser optogalvanic and jet spectroscopy of germylene (GeH2): New spectroscopic data for an important semiconductor growth intermediate

Abstract

The à 1B1–X̃ 1A1 electronic transition of germylene has been reinvestigated. A room temperature absorption spectrum of the central portion of the 000 band of GeH2 has been obtained using the technique of laser optogalvanic spectroscopy. A rotationally resolved spectrum of the 000 band of jet-cooled GeD2 has been recorded with a pulsed discharge source. Analysis of these spectra has yielded ground and excited state rotational constants for the GeH274, GeH272, GeH270, GeD276, GeD274, GeD272, and GeD270 isotopomers and approximate equilibrium structures of: r″(Ge–H)=1.5883(9) Å, θ″(H–Ge–H)=91.22(4)°, r′(Ge–H)=1.5471(6) Å, and θ′(H–Ge–H)=123.44(2)°. The ground state ν1 and ν2 vibrational frequencies have been determined from wavelength-resolved fluorescence spectra of jet-cooled GeH2 and GeD2. There is good evidence that GeH2 rotational levels with Ka′>1 are so strongly predissociated that lifetime broadening makes them diffuse, severely restricting the information that can be obtained from absorption and laser-induced fluorescence experiments.