THE VACUUM ULTRAVIOLET PHOTOABSORPTION AND PHOTOELECTRON-SPECTROSCOPY OF FLUOROCHLOROETHENES - THE 1,1-C2H2FCL, CIS-C2H2FCL AND TRANS-C2H2FCL

The vacuum ultraviolet absorption spectra of the three fluorochloroethene isomers were measured in the 6-13 eV photon energy range. Additionally, the He(I) and Ne(I) photoelectron spectra were recorded. The assignment of the various photoelectron bands is based on MNDO calculations. The vacuum UV absorption spectral features were classified in terms of Rydberg series converging to the first and second ionization energy. Besides the typical π-π* transition, other valence transitions were observed and tentatively assigned. In the geminal isomer spectrum the dominant Rydberg series converge to the first ionization limit at 10.02 eV, in the cis and trans isomers the most intense Rydberg transitions converge to the second ionization energy at 11.87 and 12.03 eV respectively. The first ionization energies of these latter compounds, obtained by Rydberg series analysis, are 9.89 and 9.87 eV respectively. An assignment of the vibrational structure observed in both spectra is proposed. © 1990.