Energy relaxation through the π*-state in C, F and O K-shell excited CF3COCH3

Total photoabsorption spectra of CF3COCH3 were measured in the C, F and O K-shell regions and the peak assignments were tentatively given. The K-shell electrons of C, F and O atoms were selectively excited into the π* orbital. The kinetic energy (KE) distribution of CF3+ formed through the π* states gave the maxima at KE = 0 and 0.43 eV. The yield of CF3+ with KE = 0 eV increased from 10 to 50% by changing the excitation sites from F 1s to O 1s. This finding was reasonably understood by considering that intramolecular energy flows from the initially excited K-shell electron to vibrational modes of CF3 group. The KE distribution of CH3+ showed a mirror image of that for CF3+.