Time-resolved photoelectron angular distributions from nonadiabatically aligned CO2 molecules with SX-FEL at SACLA

Weperformed time-resolved photoelectron spectroscopy of valence orbitals of alignedCO2 molecules using the femtosecond soft x-ray free-electron laser and the synchronized near-infrared laser. By properly ordering the individual single-shot ion images, we successfully obtained the photoelectron angular distributions (PADs) of theCO2 molecules aligned in the laboratory frame (LF). The simulations using the dipole matrix elements due to the time dependent density functional theory calculations well reproduce the experimental PADs by considering the axis distributions of the molecules. The simulations further suggest that, when the degrees of alignment can be increased up to á cos2 qñ > 0.8, themolecular geometries during photochemical reactions can be extracted fromthe measured LFPADs once the accurate matrix elements are given by the calculations.