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$\Delta-\Sigma\, CO_{2}$ BANDS IN THE SPECTRA OF VENUS AND MARS.

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/15306

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Title: $\Delta-\Sigma\, CO_{2}$ BANDS IN THE SPECTRA OF VENUS AND MARS.
Creators: Benedict, W. S.
Issue Date: 1967
Abstract: Transitions with $\Delta l = \pm 2$ are forbidden by purely vibrational selection rules but become weakly allowed when the rotational resonance interaction is taken into $account.^{1}$ Such transitions have been identified, for the first time in vibration-rotation bands, in the Connes' interferometric spectra of $Venus^{2}$ and Mars. The observed lines have $J^{\prime\prime}$ values from 16 to 56 in R-and P- branches of $5 \Delta-\Sigma$ bands of $CO_{2}$, the $\{12^{2}1,04^{2}1\}-0$ Fermi doublet and the $\{22^{2}1, 14^{2}1, 06^{2}1\}-0$ Fermi triplet. The line positions check with the observed $\Delta-\Delta$ transitions to the same upper states. The expected intensity has been calculated from the molecular constants. It may be expressed by the formula $S_{m} (\Delta-\Sigma)/S_{m}(\Sigma-\Sigma)=r_{v}J^{2} (J+1)^{2}$, where $S_{m} (\Sigma-\Sigma)$ is the strength of the corresponding line in the strongest neighboring $\Sigma-\Sigma$ band (201 II and 301 III respectively), and $r_{v}$ is a band constant. The results are: $$\begin{array}{lrrrrr}v &\multicolumn{1}{l} {121\,II}&\multicolumn{1}{l} {121\,I}&\multicolumn{1}{l}{221\,III}&\multicolumn{1}{l} {221\,II}&\multicolumn{1}{l} {221\,I}\\\nu_{0} &4887.97&5061.78&6103.67&6288.49&6474.53\\10^ {10}r_{v}-&2.03&2.24&1.89&5.33&1.77\end{array}$$ The observed lines are of the expected strength, being comparable to lines of the same m in the isotopic form $C^{16}O^{17}O$ (relative abundance $3.7.10^{-4})$ when $m{\sim}30$.
URI: http://hdl.handle.net/1811/15306
Other Identifiers: 1967-O-8
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