Photoelectron spectroscopy of coronene molecules embedded in helium nanodroplets

TL;DR

This study introduces the first extreme-ultraviolet photoelectron spectrum measurement of molecules in helium nanodroplets, revealing similarities to solid-phase spectra and highlighting the effects of helium on ionization processes.

Contribution

It provides the first PES data for molecules in helium nanodroplets and compares it to other phases, advancing understanding of ionization in such environments.

Findings

He-droplet PES resembles solid-phase PES, indicating cluster ionization.

Penning ionization spectra are highly perturbed by helium droplets.

Results enable future UPS studies of molecular clusters in helium nanodroplets.

Abstract

We present the first measurement of a one-photon extreme-ultraviolet photoelectron spectrum (PES) of molecules embedded in superfluid helium nanodroplets. The PES of coronene is compared to gas phase and the solid phase PES, and to electron spectra of embedded coronene generated by charge transfer and Penning ionization through ionized or excited helium. The resemblence of the He-droplet PES to the one of the solid phase indicates that mostly Cor clusters are photoionized. In contrast, the He-droplet Penning-ionization electron spectrum is nearly structureless, indicating strong perturbation of the ionization process by the He droplet. These results pave the way to extreme ultraviolet photoelectron spectroscopy (UPS) of clusters and molecular complexes embedded in helium nanodroplets.