Soft x-rays induce femtosecond solid-to-solid phase transition

TL;DR

This study demonstrates that soft x-rays can induce ultrafast, non-thermal solid-to-solid phase transitions in diamond within approximately 150 femtoseconds, combining experimental observation with theoretical modeling.

Contribution

First-time measurement of a femtosecond solid-to-solid phase transition in diamond induced by soft x-rays, validated by theoretical simulations.

Findings

Phase transition occurs within ~150 fs

Excellent agreement between experiment and theory

Soft x-rays can induce non-thermal ultrafast phase changes

Abstract

Soft x-rays were applied to induce graphitization of diamond through a non-thermal solid-to-solid phase transition. This process was observed within poly-crystalline diamond with a time-resolved experiment using ultrashort soft x-ray pulses of duration 52.5 fs and cross correlated by an optical pulse of duration 32.8 fs. This scheme enabled for the first time the measurement of a phase transition on a timescale of ~150 fs. Excellent agreement between experiment and theoretical predictions was found, using a dedicated code that followed the non-equilibrium evolution of the irradiated diamond including all transient electronic and structural changes. These observations confirm that soft x-rays can induce a non-thermal ultrafast solid-to-solid phase transition on a hundred femtosecond timescale.