Neutralization dynamics of slow highly charged ions passing through graphene nanoflakes--an embedding self-energy approach

TL;DR

This paper investigates the ultrafast neutralization process of slow highly charged ions passing through graphene nanoflakes using a nonequilibrium Green functions approach, providing insights into charge transfer dynamics and a semi-analytical model.

Contribution

It introduces a novel embedding self-energy method combined with NEGF to simulate charge transfer in graphene nanoflakes, aligning well with experimental data.

Findings

Charge transfer dynamics depend on ion charge state and impact velocity.

The semi-analytical model accurately predicts neutralization behavior.

Simulation results agree with transmission experiment observations.

Abstract

We study the time-dependent neutralization of a slow highly charged ion that penetrates a hexagonal hollow-centred graphene nanoflake. To compute the ultrafast charge transfer dynamics, we apply an effective Hubbard nanocluster model and use the method of nonequilibrium Green functions (NEGF) in conjunction with an embedding self-energy scheme which allows one to follow the temporal changes of the number of electrons in the nanoflake. We perform extensive simulations of the charge transfer dynamics for a broad range of ion charge states and impact velocities. The results are used to put forward a simple semi-analytical model of the neutralization dynamics that is in very good agreement with transmission experiments, in which highly charged xenon ions pass through sheets of single-layer graphene.