INTERNAL ROTATION OF THE METHYLAMINE MOLECULE IN AN EXCITED ELECTRONIC STATE.
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Date
1969
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Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The ultraviolet absorption spectrum of $CH_{3}ND_{2}$ vapor in the $2300-2450{\AA}$ region has been observed with a resolution of $3 cm^{-1}$. The rotational structure of the band at $41424 cm^{-1}$ which is assignable to the $0 \leftarrow 1$ transition of the amino-wagging vibration is explained by assuming that the internal rotation of the molecule in the lowest $(v^{1} = 0)$ vibrational state in the excited electronic state ($\bar{A}$) is a free rotation. Some of the molecular constants in the upper electronic state are determined: $\lambda = I_{CH_{3}}/I_{A} = 0.50, U = I_{CH_{3}} I_{ND_{2}}/I_{A} = 2.79 \times 10^{-40} gr. cm^{2}$, where $I_{CH_{2}}, I_{ND_{2}}$, and $I_{A}$ are the moments of inertia of the $CH_{3}$ group, the $ND_{2}$ group and the $CH_{3}ND_{2}$ molecule around the C-N bond as axis. The fine structure of the $(1,1), (0,0), (2,1), (1,0)$, and (2,0) bands were also examined. The band center frequencies are determined to be $41907_{+5}$ 42050, 42412, $42533_{+5}$ and $43039 cm^{-1}$, respectively. From these frequencies the potential function of the amino-wagging vibration was determined.
Description
Author Institution: Faculty of Pharmaceutical Sciences, University of Tokyo