Control of femtosecond laser plasma parameters by surface contaminants cleaning with preceding pulse laser

Making use of time-of-flight and mass-spectroscopic methods we investigated influence of the film on the target surface at vacuum of 10 -5 Torr onto ions emission from plasma created by femtosecond laser pulse with itensity of 2 • 10 16 W/cm 2 . It was shown that the highest energy per charge (8.5 keV) acquire protons, while basic target ions (Si, Ti) gain less energy. Heating by laser nanosecond pulse advancing femtosecond pulse by 0.1 - 100 ms with energy density up to 20 J/cm 2 allows for effective surface cleaning due to removal of molecules containing hydrogen, carbon and oxygen. By the contrast to the instantaneous resistive heating the pulsed laser cleaning provides for higher heating temperatures and can be used for any solid targets in the regimes of thermal and plasma cleaning.