Conferencia Invitada: Photoionization and photofragmentation studies on small molecular compounds using synchrotron radiation and coincidence techniques

ROSANA M. ROMANO

Campinas

Conferencia; 41st International Conference on Vacuum Ultraviolet and X-ray Physics (VUVX 2023); 2023

Brazilian Synchrotron Light Laboratory (LNLS)

Unimolecularphotofragmentation mechanisms of small molecules after photoionization withsynchrotron radiation were investigated using coincidence techniques. Theenergies of valence, shallow- and core-shell electrons were determined by VUVand X-ray absorption, as well as by the detection of ions and electrons.Transitions of these electrons to unoccupied molecular orbitals were alsoobserved in the spectra, allowing an experimental determination of their energydifferences. Valence electron ionization energies were also determined by meansof photoelectron spectroscopy. The experimental findings were interpreted aidedby ab initio and DFT theoretical calculations and Natural Bond Orbitalanalysis. The photofragmentation mechanisms after single ionization were studiedby Photoelectron-Photoion-Coincidence (PEPICO) technique as a function of theexcitation energy. Unimolecular photofragmentation mechanisms of double ionizedmolecules were inferred from the analysis of the shape and slope of thecoincidence island between two charged fragments in the bi-dimensional Photoelectron-Photoion-Photoion-Coincidence(PEPIPICO) spectra. Several examples of these studies on different families ofcompounds containing groups such as -C(O)S-, -NCO,-NCS, -SO2-, -OHand halogen atoms, will be discussed.