Pulse length dependence of photoelectron circular dichroism

Abstract

We investigate photoelectron circular dichroism (PECD) with coherent light sources whose pulse 
durations range from femtoseconds to nanoseconds. To that end, we employed an optical 
parametric amplifier, an ultraviolet optical pulse shaper, and a nanosecond dye laser, all centered 
around a wavelength of 380 nm. A multiphoton ionization experiment on the gas-phase chiral 
prototype fenchone found that PECD measured via the 3s intermediate resonance is about 15% 
and robust over five orders of magnitude of the pulse duration. PECD remains robust despite 
ongoing molecular dynamics such as rotation, vibration, and internal conversion. We used the 
Lindblad equation to model the molecular dynamics. Under the assumption of a cascading internal 
conversion, from the 3p to the 3s and further to the ground state, we estimated the lifetimes of the 
internal conversion processes in the 100 fs regime.