Pulsed discharge jet spectroscopy of DSiF and the equilibrium molecular structure of monofluorosilylene

The jet-cooled laser induced fluorescence excitation spectrum of the (A) over tilde (1)A '' - (X) over tilde (1)A' band system of DSiF has been observed using the pulsed discharge jet technique. Vibrational analysis of the spectrum yielded upper state harmonic vibrational frequencies of omega(1) = 1322, omega(2) = 444, and omega(3) = 867 cm(-1). Vibronic bands involving all, of the upper state fundamentals of HSiF and DSiF have now been rotationally analyzed, allowing a determination of the excited state equilibrium structure as r(e)'(SiH) = 1.526 +/- 0.014 Angstrom, r(e)'(SiF) = 1.597 +/- 0.003 Angstrom, and theta(e)'(HSiF) = 115.0 +/- 0.6 degrees. The harmonic frequencies and centrifugal distortion constants were used to obtain harmonic force fields and average (r(z)) structures for the ground and excited states. The ground state average structure was used to estimate the equilibrium structure of r(e) ''(SIH) = 1.528 +/- 0.005 Angstrom, r(e) ''(SiF) = 1.603 +/- 0.003 Angstrom, and theta(e) ''(HSiF) = .96.9 +/- 0.5 degrees. (C) 1997 American Institute of Physics.