Ground‐State Photoelectron Circular Dichroism of Methyl p‐Tolyl Sulfoxide by Single‐Photon Ionisation from a Table‐Top Source

Single‐photon ionisation of enantiopure methyl p‐tolyl sulfoxide by circularly polarised light at 133 nm shows remarkably strong photoelectron circular dichroism (PECD), which has been measured in a velocity‐map‐imaging spectrometer. Both enantiomers were measured, each showing a PECD of a similar magnitude (ca. 25 %). These experiments were carried out with a tabletop high‐harmonic source with a photon energy of 9.3 eV, capable of ionising the electronic ground state of most organic and inorganic molecules. Ab‐initio scattering calculations provide a theoretical value of the expected chiral asymmetry parameter, and agree very well with the measured values once orbital mixing via configuration interaction in the cation is taken into account. This study demonstrates a simple photoionisation scheme that can be readily applied to study the time‐resolved PECD of photochemical reactions and suggests a pronounced sensitivity of PECD to electronic configuration interaction in the cation.