Absolute oscillator strengths fromK-shell electron-energy-loss spectra of the fluoroethenes and 1,3-perfluorobutadiene

Absolute oscillator strengths in the region of carbon and fluorine K-shell excitation have been derived for CH₂{CH}₂$, ${CH}₂$CHF, cis-CHFCHF, ${CH}₂CF₂, CHFCF₂, CF₂{CF}₂$, 1,3-${C}₄H₆, and 1,3-C₄{F}₆$ from electron-energy-loss spectra recorded under dipole-dominated conditions. The methods used to derive absolute oscillator strengths from relative energy-loss intensities are discussed in detail. The accuracy of the procedures is tested through comparisons with literature results for N₂, CO, and CO₂. The total C 1s{→}π* and C 1s{→}σ*(C---F) intensities increase systematically as the degree of fluorination increases. The spectra are discussed in terms of bond-length correlation and potential barrier concepts.