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

## TL;DR

This study investigates how different intermediate electronic states influence the photoelectron circular dichroism in fenchone during femtosecond resonance-enhanced multi-photon ionization, revealing state-dependent effects and energy-related trends.

## Contribution

It provides the first detailed experimental analysis of intermediate state dependence of PECD in fenchone using femtosecond spectroscopy and high-resolution resonance identification.

## Key findings

- PECD sign changes with different intermediate states
- PECD magnitude decreases with increasing photoelectron energy for 3s state
- Resonances identified as involving 3s and 3p Rydberg states

## Abstract

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