Amorphous to crystalline phase transition in carbon induced by intense femtosecond x-ray free-electron laser pulses

0382680 - FZÚ 2013 RIV US eng J - Článek v odborném periodiku
Gaudin, J. - Peyrusse, O. - Chalupský, Jaromír - Toufarová, Martina - Vyšín, Luděk - Hájková, Věra - Sobierajski, R. - Burian, Tomáš - Dastjani-Farahani, S. - Graf, A. - Amati, M. - Gregoratti, L. - Hau-Riege, S.P. - Hoffmann, G. - Juha, Libor - Krzywinski, J. - London, R.A. - Moeller, S. - Sinn, H. - Schorb, S. - Störmer, M. - Tschentscher, T. - Vorlíček, Vladimír - Vu, H. - Bozek, J. - Bostedt, C.
Amorphous to crystalline phase transition in carbon induced by intense femtosecond x-ray free-electron laser pulses.
Physical Review. B. Roč. 86, č. 2 (2012), "024103-1"-"024103-7". ISSN 1098-0121
Grant CEP: GA ČR(CZ) GAP108/11/1312; GA ČR GAP205/11/0571; GA ČR GAP208/10/2302; GA AV ČR IAAX00100903; GA MŠMT EE.2.3.20.0087
Grant ostatní: OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087
Výzkumný záměr: CEZ:AV0Z10100523
Klíčová slova: amorphous carbon * phase transition * graphitization * x-ray laser * free-electron laser
Kód oboru RIV: BH - Optika, masery a lasery
Impakt faktor: 3.767, rok: 2012

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.
Trvalý link: http://hdl.handle.net/11104/0212833