Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam

J Gaudin,K Mann,B Flöter,Th Tschentscher,M Wulff,J Larsson,A Trapp,K Tiedtke,H Sinn,L Guérin,R Nüske,B Keitel,A Jurgilaitis,F Yang,B Schäfer

doi:10.1364/oe.19.015516

Abstract

We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam. By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step. The dynamics of the heat bump, build-up and relaxation, is followed with a spatial resolution in the nanometer range. The results are interpreted taking into account results of finite element method simulations. Due to its robustness and simplicity this method should find further developments at new x-ray light sources (FEL) or be used to gain understanding on thermo-dynamical behavior of highly excited materials.

Highlights

The dynamics of a surface submitted to high heat load or to high excitation is of great interest from both fundamental and application points of view
We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam
By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step

Summary

Introduction

The dynamics of a surface submitted to high heat load or to high excitation is of great interest from both fundamental and application points of view. From the application point of view, it has been addressed in the case of synchrotron optics (mirrors as well as crystal monochromators) where measurements have been performed using different techniques like in situ long trace profilers [1], or different types of Hartmann-Shack sensors [2,3]. These measurements provided sub-micron resolution in terms of height deformation, but only under steady state load. We report on such kind of time-resolved investigations in the case of a bunch train of x-ray pulses at MHz repetition rate

Methods

Results

Conclusion