Photoelectron spectroscopy of the freon molecules CF 3Cl, CF 2Cl 2 and CFCl 3 using synchrotron radiation from 41 to 160 eV

Abstract

Photoelectron spectra of the outer and inner valence regions of the freon molecules CF 3Cl, CF 2Cl 2 and CFCl 3 were obtained using synchrotron radiation in the photon energy range 41–160 eV. The spectra were analyzed using a curve fitting procedure to yield photoelectron branching ratios as a function of photon energy. These were then combined with recently measured total photoabsorption oscillator strengths to give electronic state partial photoionization oscillator strengths (cross sections). The results for CF 3Cl and CF 2Cl 2 are in generally good agreement with previously published photoelectron branching ratios. In addition the CF 3Cl data is quite successfully predicted by MS-Xα calculations. The gross features of the branching ratios and oscillator strengths with changing photon energy may be accounted for in terms of the constituent atomic orbital characters of the ionized molecular orbitals. The inner valence molecular orbitals of F 2s character are found to make large contributions to the total photoionization oscillator strength (10–20%) at photon energies above ≈ 70 eV.