ESTIMATION OF HARMONIC FREQUENCIES OF $NH_{3}, PH_{3}, AsH_{3}, SbH_{3}, ND_{3}, PD_{3}, AsD_{3}$ AND $SbD_{3}$ FROM THE OBSERVED FUNDAMENTAL FREQUENCIES.
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Date
1969
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Ohio State University
Abstract
The vibrational harmonic frequencies of these molecules have been estimated from the observed anharmonic frequencies by aid of the method proposed by $us^{1}$ to compute the harmonic frequencies of $A_{1}$ vibrations of $H_{2}O, D_{2}O, H_{2}S, H_{2}Se$ and $D_{2}Se$. This method utilizes the Wilson's splitting of the high frequency from the low in his G matrix for vibration calculation, combined with the Dennison's isotopic rule which states that the anharmonic correction is proportional to the harmonic frequency. The obtained values for $\nu_{1}$ vibrations are as follows (in $cm^{-1}$): $\begin{array}{lllll}NH_{3} & 3466.29 && ND_{3} & 2487.79\\ PH_{3} & 2471 &&PD_{3} & 1771\\ AsH_{3}& 2202.3 && AsD_{3} &1567.2\\ SbH_{3} &1981.7 && SbD_{3}& 1407.1\\\end{array}$ These values as well as those for $\nu_{2}, v_{3}$, and $v_{4}$ vibrations have been examined in comparison with the older values obtained by other methods. Finally, a dependence of the anharmonicity upon the effective nuclear charge for the valence electron of the central atom has been considered.
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$^{1}$ I. Gamo, J. Mol. Spectry 30, 216 (1969).
Author Institution: Department of Chemistry, University of Maryland
Author Institution: Department of Chemistry, University of Maryland