Quantitative spectroscopic studies of the valence-shell electronic excitation of freons (CFCl3, CF2Cl2, CF3Cl, and CF4) in the VUV and soft X-ray regions Original Research Article

Absolute photoabsorption spectra of the single carbon Freon molecules, CFCl3, CF2Cl2, CF3Cl, and CF4, have been measured from 5 to 60 eV at 0.05 eV resolution by high-resolution dipole (e,e) spectroscopy. Long-range valence-shell data (5–200 eV) obtained at lower resolution (1 eV fwhm) have been used to determine the absolute oscillator strength scales via valence-shell Thomas-Reiche-Kuhn (VTRK) sum rule normalization. Comparisons have been made with previously reported absolute photoabsorption data obtained by optical and electron impact based measurements where such data are available. The static electric-dipole polarizabilities of CFCl3, CF2Cl2, CF3Cl and CF4 derived from the S(−2) sum-rule using the present photoabsortion oscillator strength (cross-section) data are found to be in excellent agreement (within 1–2%) with experimentally measured polarizability values in the literature.