Journal of Chemical Physics, Vol.110, No.9, 4254-4257, 1999
The vibrational spectrum and molecular constants of silicon dihydride SiH2 in the ground electronic state
The infrared spectrum of SiH2 was observed in the 5 mu m region by using diode laser spectroscopy, and the three bands v(1), 2v(2), and v(3) were recorded and assigned. A separate analysis of the three bands yielded the band origins, 1995.9280, 1987.6938, and 1992.816 cm(-1), respectively, thereby establishing that v(1) is higher than 2v(2), contrary to the result of a previous matrix study. The anharmonic resonances, both v(1)/2v(2) Fermi and 2v(1)/2v(3) Darling-Dennison, which were observed in the laser induced fluorescence spectra previously reported, were reanalyzed by removing the condition v(1)<2v(2), leading to a much improved set of vibrational parameters. The harmonic frequencies of SiH2 were then obtained to be omega(1) = 2076.55, omega(2) = 1020.49, and omega(3) = 2065.65 cm(-1). Molecular constants of SiH2 in the ground vibronic state were reexamined in light of the present as well as other spectroscopic results recently obtained on the molecule.