Neutral dissociation of hydrogen following photoexcitation of HCl at the chlorineKedge

Abstract

Time-of-flight mass spectroscopy was used to study the relaxation dynamics of HCl following photoexcitation in the vicinity of the Cl $K$ edge $\left(\sim 2.8\mathrm{keV}\right)$ 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 ${\mathrm{Cl}}^{n+}$ ion. The present work demonstrates that neutral-atom emission can be a significant decay channel for excited states with very short lifetimes (1 fs).