X-ray photoemission molecular orbitals of hydrogen fluoride and the fluorinated methanes

The x-ray photoemission molecular orbital spectra of gaseous hydrogen fluoride and the fluorinated methanes (CHn F4−n, 0≥ n ≥4) are reported. Ab initio, Koopman's theorem energies and a three-parameter relaxation model were used to fit the experimental binding energies. Excellent agreement was obtained. Relative intensities of molecular orbitals were computed using the model of Gelius with both CNDO/2 and ab initio atomic populations. In the case of ab initio results, net populations were found to be superior to gross populations in reproducing the experimental intensities. In most cases, the theory predicted intensities quite well. Some trends exhibited by the fluoromethane series are noted.