BRANCHING RATIOS FOR ION-PAIR FORMATION FROM CF3CL PHOTOEXCITED IN THE INNER-SHELL TRANSITION REGIONS

Positively charged ion pairs produced from CF3Cl have been measured using the selective photoion-photoion coincidence technique and monochromatized synchrotron radiation. The branching ratios for ion-pair production were obtained from the measured coincidence signals at typical photon energies below and above the Cl L(2,3)-edges, the C K-edge and the F K-edge. The ion pair F+-Cl+ yielded the highest branching ratio at most photon energies, with Cl+-CF+ the second highest below the F K-edge. However, the Cl+-CF3+ ion pair exhibited the greatest ratio only just above the Cl L(2,3)-edges and showed low ratio at other energies. This finding is ascribed to the so-called site-specific reaction in which the breaking of the chemical bond takes place predominantly at the position of the excited atom, Cl. Partial yield spectra of ion pairs have been measured around the Cl L(2,3)-edges, the C K-edge, and the F K-edge, and the features of many ion pairs are similar to those found in photoabsorption spectra.