Infrared–infrared double resonance investigation of theN=2 andN=3 stretching manifolds of silane and the local mode model

Cavity ring-down spectroscopy of jet-cooled silane isotopologues in the Si-H stretch overtone region

Absorption spectra of silane in the region of the first overtone of the Si-H stretch vibration have been recorded in a seeded supersonic jet expansion by cavity ring-down spectroscopy as well as in a static gas cell at room temperature by photoacoustic spectroscopy. Spectral simplification due to strong rotational cooling in the jet expansion enables us to clearly resolve and assign the rovibrational transitions of the (2000) and (1100) bands of the three isotopologues, (28)SiH(4), (29)SiH(4), and (30)SiH(4), in their natural isotopic abundance. Interconversion between different nuclear spin species of SiH(4) is found to be absent during the jet expansion. Isotope shifts for (29)SiH(4) and (30)SiH(4) relative to (28)SiH(4) are measured and found to be suitable for selective vibrational excitation of any of three silane isotopologues by pulsed laser excitation in a jet expansion.

Absorption Intensity of Stretching Overtone States of Silane and Germane

The band absorbance and line absorbance of R branch transitions are obtained from high-resolution Fourier transform measurement of silane and germane local mode overtones (n000), n = 1-5, under proper sample pressures and absorption lengths. The absorption coefficients of these overtones are derived by linear least-squares fitting. The relative intensities of overtones can be satisfactorily reproduced with the bond dipole model containing two adjustable parameters. Copyright 1998 Academic Press.