Absolute photoabsorption cross section of CCl4 in the energy range 6–250 eV Original Research Article

The absolute photoabsorption cross section of CCl4 was determined in an energy range 6–250 eV by using synchrotron radiation as a light source. A total valence-shell oscillator strength of 33.14, which includes a value of 30.33 from 6 to 198 eV plus a contribution of 2.81 from 198 eV to infinity, was directly derived by summing the underlying area of the photoabsorption spectrum from valence excitations. The cross section determined in such a broad energy range was compared with those of previous measurements mostly in limited energy ranges. Several new electronic transitions were observed and tentatively assigned in both the valence and chlorine 2p excitation regions. According to the assignment, the quantum defects of (2.02±0.08), (1.64±0.05), and (0.29±0.04) were obtained for the chlorine 4s and 5s, 3p, and 3d orbitals, respectively.