Laser system with a regenerative amplifier for generation of trains of pulses of variable amplitude

Abstract

Cold plasma treatments of polymers induce surface transformations through several mechanisms involving photons, charges, radicals and excited species produced in the discharge. We have isolated the UV interaction contribution to the total luminescence emitted by the polymer after plasma discharge. Spectral and time-resolved light analyses have shown that the emitted light is constituted of the same components as in plasma-induced luminescence, namely photoluminescence, chemiluminescence and charge-recombination contributions. The essential differences were found in the dependence of the emission upon the treatment time. The luminescence intensity following plasma interaction decreased for increasing treatment time, whereas the UV interaction led to increasing emission followed by a steady-state luminescence level. In addition, the spectral distribution after a long exposure to UV did not evolve in an irreversible fashion. Some features of the time-dependence of the total intensity have been explained on the bases of luminescence decay analyses following conventional photoluminescence excitation. Whereas plasma interaction induced strong surface transformations, UV probably acts through more selective processes such as initiation of decomposition of hydroperoxides.

Breakdown in the rare gases using single picosecond ruby laser pulses

“…Values of m are stated in figure 2, determined by a weighted least-squares fit. It is not known why, for helium and argon, the results differ from those of Krasyuk et al (1970), but they are consistent with measurements taken previously at 1-06 and 0.53 pin.…”