High-Temperature Microwave Spectroscopy : AlF and AlCl

Abstract

Microwave transitions of gaseous AlF and AlCl have been studied in a high‐temperature spectrometer. The molecular constants obtained for AlF are: $B_e\text{=16 562.56\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,\alpha }}_e\text{=148.40\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,r}}_e{\text{=1.65437\hspace{0.17em}Å,(eqQ)}}_{\mathrm{A}1}\text{=−37.6\hspace{0.17em}}\mathrm{Mc}/\sec \text{,μ=1.53\hspace{0.17em}}\mathrm{D}\mathrm{;\hspace{0.17em}}\mathrm{for}\hspace{0.17em}{\mathrm{Al}}^{35}\mathrm{Cl}:{\mathrm{B}}_e\text{=7312.74\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,\alpha }}_e\text{=48.03\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,r}}_e{\text{=2.12983\hspace{0.17em}Å,(eqQ)}}_{\mathrm{A}1}\text{=−29.2\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,(eqQ)}}_{\mathrm{C}1}\text{=−8.8\hspace{0.17em}}\mathrm{Mc}/\sec \mathrm{;\hspace{0.17em}}\mathrm{for}\hspace{0.17em}{\mathrm{Al}}^{37}\mathrm{Cl}{\mathrm{:B}}_e\text{=7140.69\hspace{0.17em}}\mathrm{Mc}/\sec {\mathrm{,\alpha }}_e\text{=46.34\hspace{0.17em}}\mathrm{Mc}/\sec$ . The nature of the bonding in aluminum halides is discussed; it is concluded that the bonds are highly ionic and that the Al orbitals are sp hybrids. The details of the high‐temperature spectrometer are given.