Interpretation of the vapor spectrum of UCl4

Optical spectra of vaporized UCl₄ have been re‐examined using refined spectroscopic techniques. Improved resolution and extension of the spectral range to include the near and far infrared have allowed us to make assignments on the basis of a tetrahedral crystal field model. Calculations based upon simultaneous diagonalization of electrostatic, spin‐orbit coupling, and crystal field effects yield an excellent account of the observed spectral features, including a number of ``hot bands,'' in terms of the following parameters: $F_2{\text{= 159.1 ± 1.5;\hspace{0.17em}F}}_4{\text{= 45.76 ± 0.77;\hspace{0.17em}F}}_6{\text{= 2.31 ± 0.08;\hspace{0.17em}ζ = 1756± 9;\hspace{0.17em} A}}_4{\mathrm{〈r}}^4{\text{〉 = − 817.4± 15.5;\hspace{0.17em}A}}_6〈{\mathrm{r}}^6{\text{〉 = − 71.20± 5.52;\hspace{0.17em}ν}}_3{\text{= 330 ± 20;\hspace{0.17em}ν}}_4\text{= 110 ± 15\hspace{0.17em}(}{\mathrm{all\; units\; in\; cm}}^{\text{−1}})$ . The magnitude of these parameters is discussed in terms of those reported by other workers.