ABSORPTION CONTINUA OF BORON IODIDES
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Date
1962
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Ohio State University
Abstract
The absorption spectrum of $BI_{3}$ in the gaseous state showed a strong continuum in the region from A3150 to about $2500 {\AA}$. This continuum, due to the molecule $BI_{3}$ is in agreement with the value extrapolated from the known known continua of the related trihalides of boron and $aluminum.^{1}$ Following Schumb, Gamble, and $Banus,^{2}$ the lower iodides of boron were prepared in the absorption cell by passing an electrodeless discharge through $BI_{3}$ vapor. The absorption spectra of these lower iodides of boron revealed the existence of four continua in the regions $\lambda 2508-2790 {\AA}, \lambda 2821-2985 {\AA}, \lambda 3040-3203 {\AA}$, and $\lambda 3376-3585 {\AA}$. Of the continuum in the region $\lambda 3376-3585 {\AA}$ is the strongest, with a maximum at $\lambda 3456 {\AA}$. and the $\lambda 3040-3203 {\AA}$ continuum is the weakest. Previous work on the spectra of the diatomic halides of group III $elements^{3}$ has shown that the strongest continuum can be attributed to the diatomic molecule BI. It represents a $^{1}\Pi-^{1}\Sigma$ transition, with the upper $^{1}\Pi$ state repulsive. The dissociation energy of BI is approximately 3,5 ev if in its repulsive state it dissociates to $B(^{2}P_{1/2})$ and $1(^{2}P_{3/2})$, the lowest of the atomic states. If the molecule dissociates to $B(^{2}P_{1/2})$ and an excited $I(^{2}P_{1/2})$, then the dissociation energy is approximately 2.5 ev.
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$^{\ast}$ Present address: Department of Chemistry, University of Toronto, Toronto 5. Canada. $^{1}$ R. S. Sharma, Bull. Acad. Sci. (Allahabad, India) 3, 87 (1933). S. C. Deb. Bull. Acad. Sci. (Allahabad, India) 1, 92 (1931-32). $^{2}$ W. C. Schumb, E. L. Gamble, and M. D. Banus, J. Am. Chem. Soc, 71,3225 (1949). $^{3}$ E. Miescher, Helv. Phys. Acta, 9, 693 (1936).
Author Institution: Department of Physics, Syracuse University
Author Institution: Department of Physics, Syracuse University