Ab initio investigation of the electronic spectrum of the chloroformyl radical ClCO

An ab initio MRD-CI study is carried out to obtain a theoretical prediction of the vertical electronic spectrum of the chloroformyl radical ClCO up to energies of approximately 9 eV, including Rydberg s and p states. Furthermore, an estimation of the oscillator strengths for doublet transitions is given. The spectrum is characterized by three low-lying doublet states at 3.2, 3.4 and 3.7 eV, whereas the first quartet states as well as the first members of the Rydberg series are located in the energy region between 6.3 and 7.5 eV. Parallels are drawn with corresponding theoretical data obtained for the formyl and fluoroformyl radicals.