Time-Resolved X-ray Photoelectron Spectroscopy: Ultrafast Dynamics in CS2 Probed at the S 2p Edge

Recent developments in X-ray free-electron lasers haveenableda novel site-selective probe of coupled nuclear and electronic dynamicsin photoexcited molecules, time-resolved X-ray photoelectron spectroscopy(TRXPS). We present results from a joint experimental and theoreticalTRXPS study of the well-characterized ultraviolet photodissociationof CS2, a prototypical system for understanding non-adiabaticdynamics. These results demonstrate that the sulfur 2p binding energyis sensitive to changes in the nuclear structure following photoexcitation,which ultimately leads to dissociation into CS and S photoproducts.We are able to assign the main X-ray spectroscopic features to theCS and S products via comparison to a first-principles determinationof the TRXPS based on ab initio multiple-spawningsimulations. Our results demonstrate the use of TRXPS as a local probeof complex ultrafast photodissociation dynamics involving multimodalvibrational coupling, nonradiative transitions between electronicstates, and multiple final product channels.

Automated summary

Recent developments in X-ray free-electron lasers have enabled a novel site-selective probe of coupled nuclear and electronic dynamics in photoexcited molecules, known as time-resolved X-ray photoelectron spectroscopy (TRXPS). In this study, we investigate the ultraviolet photodissociation of CS2 and demonstrate that the binding energy of sulfur 2p is sensitive to changes in nuclear structure, leading to dissociation into CS and S photoproducts. The main X-ray spectroscopic features are assigned to the CS and S products using ab initio multiple-spawning simulations.