Single-photon hot electron ionization of C$_{70}$

TL;DR

This study investigates the ionization of C70 molecules using single photons across a range of energies, revealing hot electron dynamics and proposing a new mechanism called Resonance Ionization Shadowing for hot electron creation.

Contribution

It introduces the Resonance Ionization Shadowing mechanism, explaining hot electron generation in molecules upon above-threshold photon absorption.

Findings

Doubly ionized and unfragmented C70 observed at photon energies ≥22 eV

Triply charged ions detected from 55 eV onwards

Initial electron equilibration time estimated from spectral deviations

Abstract

Gas phase C$_{70}$ molecules have been ionized with single photons of energies between 16 eV and 70 eV and the electron spectra measured with velocity map imaging in coincidence with the ions. The doubly ionized and unfragmented species was present at photon energies of 22 eV and up, and triply charged ions from 55 eV. The low kinetic energy parts of the spectra are explained with thermal emission of transient hot electrons. Deviations at high photon energies are used to determine a value for the initial electron equilibration time. We propose a generally applicable mechanism, named Resonance Ionization Shadowing, for the creation of hot electrons by absorption of above-threshold energy photons.