The Rotational Spectra Structure, Internal Dynamics and Electric Dipole Moment of Argon-Ketene Van Der Walls Complex

Published

June 1, 2001

Author(s)

C W. Gillies, J Z. Gillies, S J. Amadon, R D. Suenram, Francis J. Lovas, H Warner, R Malloy

Abstract

Pulsed-beam Fourier transform microwave spectroscopy was used to observe and assign the rotational spectra of the argon-ketene van der Waals complex. Tunneling of the hydrogen or deuterium atoms splits the a- and b-type rotational transitions of H₂CCO-Ar, H₂C¹³CCO-Ar H₂C¹³CO-Ar, and D₂CCO-Ar into two states. This internal motion appears to be quenched for HDCCO-Ar where only one state is observed. The spectra of all isotopomers were satisfactorily fit to a Watson asymmetric top Hamiltonian which gave A = 10447,9248(10) MHz, B= 1918.0138(16) MHz, C = 1606.7642(15) MHz, δ_j = 16.0856(70) kHz, δ _k = -152.24(23) kHz, δ_j = 2.5313(18) kHz, δ_k = 209.85(82) kHz, and h_k = 1.562 (64) kHz for the A₁ state of H₂CCO-Ar. Electric dipole moment measurements determined _a = 0.417(10)x10^-30 C m [0.125(3)D] and _b = 4.566 (7) x 10^-30 C m [1.369(2)D] along the a and b principal axes of the A₁ state of the normal isotopomer. A least squares fit of principal moments of inertia, I_a and I_c, of H₂CCO-Ar, H₂¹³CCO-Ar, H₂C¹³CO-Ar, and D₂CCO-Ar for the A₁ states give the argon-ketene center of mass separation, R_cm = 3.589 (1) and the angle between the line connecting argon with the center of mass of ketene and the C=C=O axis, θ_cm = 83.3 (6). The spectral data are consistent with a planar geometry and the argon atom is tilted toward the methylene carbon of ketene by 6.7 from a T-shaped configuration.

Citation

Journal of Molecular Spectroscopy

Volume

207

Pub Type

Journals

Keywords

Argon-ketene, Fourier-transform spectrum, microwave, molecular structure, rotational spectrum, spectra, van der Waals complex

Citation

Gillies, C. , Gillies, J. , Amadon, S. , Suenram, R. , Lovas, F. , Warner, H. and Malloy, R. (2001), The Rotational Spectra Structure, Internal Dynamics and Electric Dipole Moment of Argon-Ketene Van Der Walls Complex, Journal of Molecular Spectroscopy (Accessed December 11, 2023)