# Microscopic mechanism of ultrashort-pulse laser ablation of metals: a molecular dynamics study incorporating electronic entropy effects

## TL;DR

This study develops a molecular dynamics model incorporating electronic entropy effects to better understand the microscopic mechanisms of ultrashort laser pulse ablation of metals, revealing high-energy ion emission and sub-nanometer ablation near the threshold.

## Contribution

The paper introduces a novel TTM-MD simulation scheme that includes electronic entropy effects, providing new insights into metal ablation mechanisms under ultrashort laser pulses.

## Key findings

- High-energy ion emission observed near ablation threshold
- Sub-nanometer depth ablation confirmed by simulations
- Electronic entropy significantly influences spallation processes

## Abstract

The microscopic mechanism of metal ablation induced by ultrashort laser pulse irradiation is investigated. A two-temperature model scheme combined with molecular dynamics (TTM-MD) is developed to incorporate electronic entropy effects into the simulation of metal ablation while satisfying the energy conservation law. Simulation with the TTM-MD scheme reveals that ultrashort laser pulse irradiation near the ablation threshold causes high-energy ion emission and sub-nanometer depth ablation, as observed experimentally, due to the electronic entropy effect. It is also shown that the electronic entropy effect is also significant in spallation.