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



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


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, DJ = 29.089 (3) kHz and 20.0198 (8) kHz and HJ = 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.
Journal of Molecular Spectroscopy


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


Kawashima, Y. , Suenram, R. , Fraser, G. , Lovas, F. and Hirota, K. (1999), The Rotational Spectrum of Ar-SiH<sub>4</sub> and Ar--SiD<sub>4</sub>, Journal of Molecular Spectroscopy (Accessed February 21, 2024)
Created December 31, 1998, Updated October 12, 2021