The Rotational Spectrum of Ar-SiH4 and Ar--SiD4

Published

January 1, 1999

Author(s)

Y Kawashima, R D. Suenram, Gerald T. Fraser, Francis J. Lovas, Katsuya Hirota

Abstract

Microwave spectra of Ar--²⁸SiH₄, Ar--²⁹SiH₄, Ar--³⁰SiH₄, and Ar--²⁸SiD₄ have been recorded using a pulsed-molecular-beam Fourier-transform microwave spectrometer. The K = 0 and K = 1 components of the J=3 <- 2 through the J = 7 <- 6 transitions have been measured and assigned in the 9 GHz to 24 GHz region. For the primary ²⁸Si isotopic species, Ar--²⁸SiH₄ and Ar--²⁸SiD₄, a K = 0, A symmetry, a K=0, F symmetry, a doubly degenerate K = 1, E symmetry and an *}/K-doubled, K=1, F symmetry rotational progression are observed at the approximately} 1 K rotational temperature of the supersonic expansion. The rotational constants for the K = 0, A state for Ar--²⁸SiH₄ and Ar--²⁸SiD₄ are B = 1700.40624 (9) MHz and 1630.687073 (22) MHz and the centrifugal distortionconstants are, D_J = 29.089 (3) kHz and 20.0198 (8) kHz and H_J = 1.91(3) Hz and 0.851 (8) Hz, respectively, where type-A expanded uncertainties with a coverage factor, k = 3, are given here and elsewhere. The values of the rotational constants for the K = 0, A and F states and for the K = 1, E state are in good agreement with the infrared determined values for Ar--²⁸SiH₄. The measured linear Stark effect of the E-state transitions has been analyzed to give a dipole moment of 9.24(8) 10^-32 C m [0.0277(2) D]. The observed relative intensities of the internal rotor states and the magnitude of the *}-doubling splitting of the K = 1, F state are compared with predictions from a previously proposed internal-rotation potential for this complex based on an analysis of the infrared spectrum.

Citation

Journal of Molecular Spectroscopy

Volume

197

Pub Type

Journals

Keywords

argon-silane, dipole moment, Fourier transform microwave spectroscopy, molecular structure, rotational spectrum, van der Waals complex

Citation

Kawashima, Y. , Suenram, R. , Fraser, G. , Lovas, F. and Hirota, K. (1999), The Rotational Spectrum of Ar-SiH₄ and Ar--SiD₄, Journal of Molecular Spectroscopy (Accessed October 10, 2025)