Review Article 

Various damage mechanisms in carbon and silicon materials under femtosecond X-ray irradiation

¹ Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague 8, 18221, Czech Republic
² Institute of Plasma Physics, Czech Academy of Sciences, Za Slovankou 3, Prague 8, 18200, Czech Republic
³ Institute for Laser and Optics, Hochschule Emden/Leer − University of Applied Sciences, Constantiaplatz 4, 26723 Emden, Germany
⁴ Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
⁵ Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
⁶ Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland

^* Corresponding author: nikita.medvedev@fzu.cz

Received: 14 February 2018
Accepted: 24 June 2018

Abstract

We review the results of our research on damage mechanisms in materials irradiated with femtosecond free-electron-laser (FEL) pulses. They were obtained using our hybrid approach, X-ray-induced thermal and non-thermal transitions (XTANT). Various damage mechanisms are discussed with respect to the pulse fluence and material properties on examples of diamond, amorphous carbon, C₆₀ crystal, and silicon. We indicate the following conditions: those producing thermal melting of targets as a result of electron-ion energy exchange; non-thermal phase transitions due to modification of the interatomic potential; Coulomb explosion due to accumulated net charge in finite-size systems; spallation or ablation at higher fluences due to detachment of sample fragments; and warm dense matter formation. Transient optical coefficients are compared with experimental data whenever available, proving the validity of our modeling approach. Predicted diffraction patterns can be compared with the results of ongoing or future FEL experiments. Limitations of our model and possible future directions of development are outlined.