RECENT RESULTS IN THE ANALYSIS OF FUNDAMENTAL, HARMONIC AND COMBINATION BANDS OF SOME $XY_{4}$ MOLECULES.
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Date
1979
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Ohio State University
Abstract
Recent results have been obtained in the analysis of vibration-rotation spectra of light $XY_{4}$ molecules, using a new tetrahedral formalism developed in the DIJON $Laboratory^{1}$. Two main results are reported: -(i) Treatment of interacting fundamentals ($\nu_{4}$ and $\nu_{4}$ of $CH_{4}$ and $SiH_{4}$; $\nu_{1}$ and $\nu_{3}$ of $SiH_{4}$) with an untransformed third-order Hamiltonian. A reduced set of parameters given better results than previous fourth order theories. -(ii) Analysis of harmonic and combination bands by a systematic extrapolation from the corresponding fundamental: $2\nu_{2}, 2\nu_{4}, \nu_{2}, + \nu_{4}$ and $\nu_{2} + \nu_{3}$ of methane. As a consequence, a first set of anharmonic constants have been obtained. Several works in progress are briefly discussed: -(i) Treatment of interacting vibrational clusters. (The pentade $\nu_{1} - \nu_{3} - 2\nu_{2} - 2\nu_{4} -\nu_{2} + \nu_{4}$ of $CH_{4}$). -(ii) Computation of hot bands. -(iii) Analysis of levels involving more than two vibrational quanta.
Description
$^{1}$J.P. CHAMPION, J. Can. Phys., 55, 1802-1828 (1977)
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