Electronic state influence on selective bond breaking of core-excited nitrosyl chloride (ClNO)

Abstract

The potential for selective bond breaking of a small molecule was investigated with electron-spectroscopy and electron-ion coincidence experiments on ClNO. The electron spectra were measured upon direct valence photo-ionization and upon resonant core-excitation at the N 1s- and O 1s-edges followed by emission of resonant Auger (RA) electrons. The RA spectra were analyzed with particular emphasis on the assignment of the participator and spectator states. The latter are of special relevance for investigations of how distinct electronic configurations influence selective bond breaking. The electron-ion coincidence measurements provided branching fractions of the produced ion-fragments as a function of electron binding energy. It explicitly demonstrates the influence of the final electronic states created after the photo-ionization and RA decay, on the fragmentation. In particular, we observe a significantly different branching fraction for spectator states compared with participator states. The bonds broken for the spectator states are also found to correlate with the anti-bonding character of the spectator-electron orbital.

Deconvolution of the X-ray absorption spectrum of trans-1,3-butadiene with resonant Auger spectroscopy

“…If the subsequently formed valence hole remains sufficiently localised in the proximity of the core hole, site-selective chemical dynamics can occur. Such phenomena have been observed experimentally for a number of photofragmentation processes 6–10 and predicted theoretically for non-dissociative processes such as photoisomerisation. 11…”

Double Photoionization of Nitrosyl Chloride by Synchrotron Radiation in the 24–70 eV Photon Energy Range

“…These previous ion–ion coincidence measurements on the ClNO dication [ 27 , 28 ] formed after core excitation at different pre-edge resonances have pointed out the Cl-N bond cleavage with the formation of NO + ions. It has been observed that excitation of similar molecular orbitals of ClNO [ 26 ] (from the N and O atoms) results in different fragmentation patterns [ 27 , 28 ].…”

“…Double photoionization was studied in a previous experiment mainly dedicated to photoelectron spectroscopy (PES) and X-ray absorption spectroscopy (NEXAFS) in order to deeply characterize the electronic structure of ClNO through a combined experimental and theoretical spectroscopic investigation at the Cl 2p, Cl 2s, N 1s and O 1s edges [ 26 ]. After that, resonant Auger spectra measurements have been taken together with atomic/molecular products ion coincidence detection with resonant Auger electrons [ 27 , 28 ].…”

“…The inner shell electronic structure and dissociation dynamics of nitrosyl chloride were already studied by our group at the Gas Phase Beamline of the Elettra Synchrotron Facility in Trieste (Italy) [ 26 , 27 , 28 ].…”

Tracking Molecular Fragmentation in Electron–Ionization Mass Spectrometry with Ultrafast Time Resolution

“…Such an experiment would answer questions related to local versus global ionization. Recently, L-edge X-ray absorption has been used to affect product branching. , Such experiments could be used to explore element-specific ionization and intramolecular energy redistribution rates in larger molecules.…”