CHEMICAL-REACTION JET SPECTROSCOPY, MOLECULAR-STRUCTURE, AND THE BENDING POTENTIAL OF THE (A)OVER-TILDA-(1)A''' STATE OF MONOFLUOROSILYLENE(HSIF)

The jet-cooled laser induced fluorescence excitation spectrum of the ( $) over tilde A (1)A''-($) over tilde X (1)A' band system of HSiF has been observed with the chemical reaction jet technique. Vibrational an alysis of the spectrum gave upper state fundamental vibrational freque ncies of v(1)=1547 cm(-1), v(2)=558 cm(-1) and v(3)=857 cm(-1). Seven bands in the spectrum were recorded at high resolution and rotationall y analyzed, providing excited state molecular constants. The upper sta te vibrational and rotational bending levels were fitted to a semirigi d bender model to obtain the equilibrium geometry and the potential en ergy barrier to linearity. Due to correlations in the parameters, it w as necessary to fix the bond angle at the ab initio value of 114.5 deg rees. The resulting fitted model yielded r(e)(Si-F)=1.602 Angstrom, r( e)(Si-H)=1.548 Angstrom with a potential energy barrier to linearity o f 9130 cm(-1). (C) 1995 American Institute of Physics.