INTERPRETATION OF THE $\nu_{1}$ AND $\nu_{3}$ BANDS OF $PH_{3}$
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Date
1978
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Publisher
Ohio State University
Abstract
The analysis of the $\nu_{1}(A_{1})$ and the $\nu_{3}(E)$ fundamental vibration-rotation bands of $PH_{3}$ in the spectral interval $2440-2190\;cm^{-1}$ has been carried out on spectra obtained with an effective spectral resolution of about $0.03\;cm^{-1}$. The $\ell$-type and the K-type doubling affecting the $k \ell = 1,-2$ levels of $\nu_{3}$ have been observed. A computer program therein the ordinary centrifugal distortion terms up to the sixth power terms of the angular momentum operator which explicitly treats the above cited resonances together with the $``2, -1^{\prime\prime}$ and the Coriolis resonance between the $\nu_{1}$ and $\nu_{3}$ was set up to simultaneously fit the data for these two bands which are separated by only $5.7\;cm^{-1}$. However, these interactions seem to be insufficient in explaining the pattern of the $PH_{3}$ spectrum even for low J quantum numbers. The band centers obtained for the transitions are: \begin{eqnarray*} \nu_{1}&=&2321.12 \pm 0.01\;cm^{-1}\\ \nu_{3}&=&2326.86 \pm 0.01 \;cm^{-1} \end{eqnarray*} Numerous `forbidden’ $\Delta |k-\ell|=\pm3$ transitions due to the interaction between the $\nu_{1}$ and $\nu_{3}$ robibrational levels belonging to both these states are also presented. Among she set of the observed lines, those corresponding to $k\; \ell = -2(A^{+}\;and\;A^{-}),\;k\;\ell = -3$ are found to be of comparable intensity with the lines of the two fundamental bands.
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Author Institution: Department of Physics, The Ohio State University