INFRARED-RADIOFREQUENCY DOUBLE RESONASCE SPECTROSCOPY OF CH3F USING A COLOR CENTER LASER
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Date
1988
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Ohio State University
Abstract
The color center laser is continuously tunable between $2.3 - 3.3 \mu m$ with single mode power between 1 - 15 mW. This relatively high power makes infrared. radiofrequency double resonance spectrocopy possible [1]. We have used this technique to study the $A_{1}-A_{2}$ splitting of $CH_{3}F$ in the $\nu_{4} (J. K=1, 1=1$ and $J, K=2, 1=1$) state. This splitting can be represented by $\Delta \nu=\frac{(J+KY)!}{(J-KY)!}\left\{q+qiJ(J+1)+q_{JJ}J^{2}(J+1)^{2}.\right\}$ where the second and third terms are centrifugal distortion terms. We determined $q=16.04466(53) MHz. q_{J}=3.523(29) KHz$ and $q_{JJ}=2.53(36) Hz$ for $K=1, l=1$ and $q=6.88835(72) KHz. q_{J}=4.6124(70) Hz$ and $q_{JJ}=2.444(16)\times 10^{-3}$ Us for $K=2. l=.1$ We also measured the electric dipole moment of $CH_{3}F$ in the $\nu_{4}$ state using this technique. By applying a Stark field perpendicular to the Rf radiation, we could observe the splitting between M-components in the ground and $\nu_{4}$ states. Using the ratio of this splitting (when $J^{\prime\prime} = K^{\prime\prime}$ and $J^{\prime} = K^{\prime})$ the dipole moment can be calculated according to $\mu^{\prime}=\mu^{\prime\prime} =\frac{\Delta \nu^{\prime}(J^{\prime}+1)}{\Delta \nu^{\prime\prime}(J^{\prime\prime}+1)}$ which is independent of the Stark field. We determined $\mu^{\prime} = 1.8332(23) D$, which is calculated using the ground state dipole moment, $\mu^{\prime\prime}=1.8585(5) D$, accurately determined by molecular beam electric resonance [2]. This study was conducted as a preliminary experiment for the planned IR-RF and IR-MW double resonance spectroscopy of molecular ions, which is in progress and will also be discussed.
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$^{1}$ It. I. Deleon. P. H. Jones, and J. S. Muenter, Appl. Opt. 20.525(1981) $^{2}$ S. C. Woby. J. S. Muenter, and W. Klempere, J. Chem Phys55. 2014(1971)
Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Istituto Di Spettroscopia, Molecolare Del C. N. R. Via De3 Castagnoli1
Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Istituto Di Spettroscopia, Molecolare Del C. N. R. Via De3 Castagnoli1