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



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


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, δj = 16.0856(70) kHz, δ k = -152.24(23) kHz, δj = 2.5313(18) kHz, δk = 209.85(82) kHz, and hk = 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, Ia and Ic, of H2CCO-Ar, H213CCO-Ar, H2C13CO-Ar, and D2CCO-Ar for the A1 states give the argon-ketene center of mass separation, Rcm = 3.589 (1) and the angle between the line connecting argon with the center of mass of ketene and the C=C=O axis, θcm = 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.
Journal of Molecular Spectroscopy


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


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)
Created May 31, 2001, Updated October 12, 2021