Eur. Phys. J. D (2013) 67: 55
https://doi.org/10.1140/epjd/e2013-30497-7

Regular Article

Hard X-ray generation and plasma filament formation under interaction of femtosecond laser pulses with large molecular clusters

¹ Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
² Faculty of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
³ International Laser Center, M.V. Lomonosov Moscow State University, Leninskie Gory, 119899 Moscow, Russia

^a e-mail: irina.zhvaniya@physics.msu.ru

Received: 10 August 2012
Received in final form: 12 November 2012
Published online: 19 March 2013

Abstract

We have demonstrated that the efficiency of hard X-ray generation (with energy 2 − 4 keV) from the femtosecond laser excitation (intensity I ~ 10¹⁶ W/cm², pulse energy E ~ 5 mJ) of large molecular clusters (SF₆, CF₃I) can reach  ~ 10^-6 (with yield  ~ 10⁹ photons/J). It was shown that at maximal X-ray yield, the plasma filament is essentially non-uniform and has a multifocal structure. It was observed that the amplitude of the central and trailing spectral components of the chirped laser pulse decreases after its interaction with the cluster target as a result of efficient laser energy absorption under self-focusing conditions.