Intermediate state dependence of the photoelectron circular dichroism of fenchone observed via femtosecond resonance-enhanced multi-photon ionization

摘要

The intermediate state dependence of photoelectron circular dichroism (PECD)in resonance-enhanced multi-photon ionization of fenchone in the gas phase isexperimentally studied. By scanning the excitation wavelength from 359 to 431nm we simultaneously excite up to three electronically distinct resonances. Inthe PECD experiment performed with a broadband femtosecond laser theirrespective contributions to the photoelectron spectrum can be resolved.High-resolution spectroscopy allows us to identify two of the resonances asbelonging to the B- and C-bands, which involve excitation to states with 3s and3p Rydberg character, respectively. We observe a sign change in the PECD signaldepending on which electronic state is used as an intermediate. Additionally,scanning the laser wavelength reveals a decrease of PECD magnitude withincreasing photoelectron energy for the 3s state.