%0 Artikel
%@ 1098-0121
%A Gaudin, J.
%A  Peyrusse, O.
%A  Chalupsky, J.
%A  Toufarova, M.
%A  Vysin, L.
%A  Hajkova, V.
%A  Sobierajski, R.
%A  Burian, T.
%A  Dastjani-Farahani, S.
%A  Graf, A.
%A  Amati, M.
%A  Gregoratti, L.
%A  Hau-Riege, S.P.
%A  Hoffmann, G.
%A  Juha, L.
%A  Krzywinski, J.
%A  London, R.A.
%A  Moeller, S.
%A  Sinn, H.
%A  Schorb, S.
%A  Stoermer, M.
%A  Tschentscher, T.
%A  Vorlicek, V.
%A  Vu, H.
%A  Bozek, J.
%A  Bostedt, C.

%D 2012
%J Physical Review  B
%N 1368
%P 024103 
%R doi:10.1103/PhysRevB.86.024103
%T Amorphous to crystalline phase transition in carbon induced by intense femtosecond x-ray free-electron laser pulses
%U http://dx.doi.org/10.1103/PhysRevB.86.024103
2 
%X We present the results of an experiment where amorphous carbon undergoes a phase transition induced by femtosecond 830 eV x-ray free-electron laser pulses. The phase transition threshold fluence is found to be 282 ± 11 mJ/cm2. Atomic force microscopy, photoelectron microscopy, and micro-Raman spectroscopy give experimental evidence for the phase transition in terms of a volume expansion, graphitization, and change of
local order of the irradiated sample area. The interaction is modeled by an accurate time-dependent treatment of the ionization dynamics coupled to a two-temperature model. At the phase transition fluence threshold the free-electron density Ne is found to be at maximum 9 × 1020 cm−3 while the ion (atom) temperature is found to be 1050 K, e.g., above the crystallization activation temperature reported in the literature. This low ionization
rate and high atom temperature suggest a thermally activated phase transition.