OVERTONES OF THE INFRARED ACTIVE FUNDAMENTALS OF TETRAHEDRAL $XY_{4}$ MOLECULES $(2\nu_{3}$, AND $2\nu_{4}$ of $CH_{4}, 2\nu_{3}$ OF $CD_{4}$)
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Date
1961
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Ohio State University
Abstract
The spherical tensor $formalism^{1}$ is applied to rotation-vibration interactions in the first overtones of the infrared active fundamentals of tetrahedral $XY_{4}$ molecules. Theory predicts five P, Q and R branches of comparable intensity provided that the separation of the E and $F_{2}$ vibrational components of the $l = 2$ vibrational state is small compared with the splittings which arise from the $2B\zeta\;\stackrel{\rightarrow \rightarrow}{(P.l)}$ term. $2\nu_{4}{^{2}}$ of $CH_{4}$ falls into this category. If, however, the separation between the E and $F_{2}$ vibrational components is very large, theory predicts an overtone spectrum with a single strong P, Q and R branch structure. In that case transitions to the levels associated with the E vibrational substate are extremely weak, and the P, Q, and R lines associated with the $F_{2}$ vibrational substate are similar to those of the fundamentals. $2\nu_{3}$ of both $CH_{4}{^{3}}$ and $CD_{4}{^{4}}$ fall into this second category, although the splitting of lines belonging to the same J value is much larger in $CD_{4}$. Several molecular constatnts for $CH_{4}$, and $CD_{4}$ have been determined from a detailed quantitative analysis of these bands.
1960
1960
Description
$^{*}$ National Science Foundation Predoctoral Fellow. $^{1}$ K. T. Hecht. J. Mol. Spectroscopy 5, 355 (1960). $^{2}$ E. K. Plyler, E. D. Tidwell, and L. R. Blaine, J. Res. Nat. Bur. Stand. 64A, 201 (1960) 3. D. H. Rank, D. P. Eastman, G. Skorinko, and T. A. Wiggins, J. Mol. Spectroscopy 1, 78 (1960). $^{4}$E. D. Palik; R. E. Meredith and C. W. Peters (private communications).
Author Institution: The Harrison M, Randall Laboratory of Physics, The University of Michigan, Ann Arbor
Author Institution: The Harrison M, Randall Laboratory of Physics, The University of Michigan, Ann Arbor