TY - GEN
T1 - Non-thermal phase transitions in semiconductors under femtosecond XUV irradiation
AU - Medvedev, Nikita A.
AU - Jeschke, Harald O.
AU - Ziaja, Beata
PY - 2013
Y1 - 2013
N2 - When a semiconductor or a dielectric is irradiated with ultrashort intense X-ray pulse, several processes occur: first the photoabsorption brings the electron subsystem out of equilibrium, bringing valence or deeper shells electrons into high energy states of the conduction band. Then, secondary electron cascading promotes further electrons of the valence to conduction band increasing their number there. These electrons also influence the atomic motion, modifying the interatomic forces. This process is known as a nonthermal melting. It can turn a material into a new phase state on ultrashort timescales. Recently developed hybrid model for treating all of these processes with different computational tools was reported in [N. Medvedev et al, New J. Phys. 15, 015016 (2013)]. Based on this model, we present here further investigations of nonthermal processes occurring in diamond under irradiation with a FLASH pulse of 10 fs FWHM and 92 eV photon energy. It is shown that the diamond turns into graphite under such irradiation, independently whether constant pressure or constant volume modeling is performed. However, for the latter case, the time of the nonthermal phase transition is longer (few tens of fs for P=const vs few hundreds of fs for V=const) and the damage threshold is slightly higher (0.69 eV/atom vs 0.74 eV/atom, correspondingly).
AB - When a semiconductor or a dielectric is irradiated with ultrashort intense X-ray pulse, several processes occur: first the photoabsorption brings the electron subsystem out of equilibrium, bringing valence or deeper shells electrons into high energy states of the conduction band. Then, secondary electron cascading promotes further electrons of the valence to conduction band increasing their number there. These electrons also influence the atomic motion, modifying the interatomic forces. This process is known as a nonthermal melting. It can turn a material into a new phase state on ultrashort timescales. Recently developed hybrid model for treating all of these processes with different computational tools was reported in [N. Medvedev et al, New J. Phys. 15, 015016 (2013)]. Based on this model, we present here further investigations of nonthermal processes occurring in diamond under irradiation with a FLASH pulse of 10 fs FWHM and 92 eV photon energy. It is shown that the diamond turns into graphite under such irradiation, independently whether constant pressure or constant volume modeling is performed. However, for the latter case, the time of the nonthermal phase transition is longer (few tens of fs for P=const vs few hundreds of fs for V=const) and the damage threshold is slightly higher (0.69 eV/atom vs 0.74 eV/atom, correspondingly).
KW - Free-Electron Laser FLASH
KW - Graphitization of diamond
KW - Nonthermal melting
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UR - http://www.scopus.com/inward/citedby.url?scp=84880754195&partnerID=8YFLogxK
U2 - 10.1117/12.2019123
DO - 10.1117/12.2019123
M3 - Conference contribution
AN - SCOPUS:84880754195
SN - 9780819495792
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Damage to VUV, EUV, and X-Ray Optics IV; and EUV and X-Ray Optics
T2 - Damage to VUV, EUV, and X-Ray Optics IV; and EUV and X-Ray Optics: Synergy Between Laboratory and Space III
Y2 - 15 April 2013 through 18 April 2013
ER -