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

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