Relaxation dynamics of CH3Cl following core-shell photoexcitation in the neighbourhood of the chlorine K-edge ( 2.8 keV) were studied via multi-ion coincidence measurements using a time-of-flight mass spectrometer. The data provide evidence for sequential fragmentation moderated by Coulombic interactions among the fragments. The sequential nature of the fragmentation indicates that chemical forces, especially between the carbon and chlorine atoms, are dominant in determining the kinematics of the fragmentation. This is especially true on resonance where fast dissociation is observed following electron excitations to the 8a1 antibonding orbital.

Ion time-of-flight mass spectroscopy was used to study the relaxation dynamics of HCl following photoexcitation in the vicinity of the Cl K threshold ({approx}2.8 keV). Detailed observations of molecular fragmentation mediated by postcollision interaction between a photoelectron and an Auger electron are presented, evidenced by the recapture of Cl K photoelectrons by either Cl{sup n+} or H{sup +} dissociation fragments. {copyright} {ital 1998} {ital The American Physical Society}

The relaxation dynamics of HCl, DCl, H2S, and D2S following photoexcitation in the vicinities of the Cl and 8 K-shell thresholds (similar to 2.8 keV for Cl, similar to 2.5 keV for S) were studied by means of ion time-of-flight mass spectroscopy. In all cases; the onset of pre-edge core-shell photoionization precedes the formation on resonance of a significant amount of neutral hydrogen as well as postcollision-interaction effects above threshold. Examination of the width of the H+ peak in spectra taken with the analyzer parallel and perpendicular to the polarization vector of the incident light indicates that on resonance, the photofragmentation asymmetry parameter, beta, is approximately two for HCl, and is clearly positive for H2S. [S1050-2947(98)08211-0].

Time-of-flight mass spectroscopy was used to study the relaxation dynamics of HCl following photoexcitation in the vicinity of the Cl K edge (similar to 2.8 keV) using monochromatic synchrotron radiation. At the lowest resonant excitation to the 6 sigma* antibonding orbital, almost half of the excited molecules decay by emission of a neutral H atom, mostly in coincidence with a highly charged Cln+ ion. The present work demonstrates that neutral-atom emission can be a significant decay channel for excited states with very short lifetimes (1 fs).