The absorption spectrum of CoCl2 molecules isolated in a nitrogen matrix and the fluorescence spectrum of CoCl2 molecules isolated in an argon matrix have been measured at liquid helium temperatures in the range 4000–50 000 cm−1. The absorption and fluorescence spectra in the 4000–25 000 cm−1 region were not mutually observable in the same host. Interpretations of the spectra are given, based on axial ligand field calculations for a 3d7 configuration including spin-orbit coupling interactions.
J. R. Clifton and D. M. Gruen, "Electronic Absorption and Fluorescence Spectra of Matrix-Isolated CoCl2 Molecules," Appl. Spectrosc. 24, 53-59 (1970)