Enhanced production of anionic and excited neutral fragments of gaseous HCCl3 near the Cl 2p1/2,3/2 ionization threshold

Following photoexcitation of Cl 2p electrons to various resonances, the fragmentation dynamics of anionic and excited neutral fragments of gaseous HCCl3 were investigated on combining measurements of photon-induced anionic dissociation, X-ray absorption and UV/visible dispersed fluorescence. The Cl 2p core-to-Rydberg excitations near the ionization threshold produce a notable enhancement of excited neutral fragments (C* and CH*), which is explained in terms of the contribution from a shake-modified resonant Auger decay and post-collision interaction. The anion yields significantly reinforced just above Cl 2p ionization threshold of gaseous HCCl3 are predominantly mediated by photoelectron recapture through post-collision interaction. The present work demonstrates that the detection of excited neutral fragments and anions offer specific insight into the fragmentation dynamics of high-lying molecular-ion states of core-excited molecules.