Beyond the molecular movie: dynamics of bands and bonds during a photo-induced phase transition

TL;DR

This study uses femtosecond photoemission to investigate the ultrafast electronic and atomic dynamics during a photo-induced phase transition in indium nanowires, revealing detailed reaction pathways and the role of localized photo-holes.

Contribution

It provides a detailed experimental pathway of the phase transition and highlights the importance of localized photo-holes in shaping the energy landscape, supported by ab initio simulations.

Findings

Uncovered a detailed reaction pathway during the PIPT.

Identified the crucial role of localized photo-holes.

Enabled a combined momentum and real space analysis of ultrafast bond formation.

Abstract

Ultrafast non-equilibrium dynamics offer a route to study the microscopic interactions that govern macroscopic behavior. In particular, photo-induced phase transitions (PIPTs) in solids provide a test case for how forces, and the resulting atomic motion along a reaction coordinate, originate from a non-equilibrium population of excited electronic states. Utilizing femtosecond photoemission we obtain access to the transient electronic structure during an ultrafast PIPT in a model system: indium nanowires on a silicon(111) surface. We uncover a detailed reaction pathway, allowing a direct comparison with the dynamics predicted by ab initio simulations. This further reveals the crucial role played by localized photo-holes in shaping the potential energy landscape, and enables a combined momentum and real space description of PIPTs, including the ultrafast formation of chemical bonds.