Multiorbital tunneling ionization of the CO molecule

TL;DR

This study investigates the multiorbital tunneling ionization process in CO molecules using advanced laser techniques, revealing how orbital shapes influence ionization and detailing sequential electron tunneling from multiple orbitals.

Contribution

It provides the first detailed experimental analysis of multiorbital tunneling ionization in CO, including sequential electron emission and orbital shape effects.

Findings

Ionization rates depend on molecular orientation.

Sequential tunneling of two electrons from different orbitals observed.

Orbital shape significantly influences tunneling ionization.

Abstract

We coincidently measure the molecular frame photoelectron angular distribution and the ion sum-momentum distribution of single and double ionization of CO molecules by using circularly and elliptically polarized femtosecond laser pulses, respectively. The orientation dependent ionization rates for various kinetic energy releases allow us to individually identify the ionizations of multiple orbitals, ranging from the highest occupied to the next two lower-lying molecular orbitals for various channels observed in our experiments. Not only the emission of a single electron, but also the sequential tunneling dynamics of two electrons from multiple orbitals are traced step by step. Our results confirm that the shape of the ionizing orbitals determine the strong laser field tunneling ionization in the CO molecule, whereas the linear Stark effect plays a minor role.