Laser-plasma interactions in 532 nm ablation of Si

Single-crystal Si was ablated by pulsed 532 nm laser radiation, and the vol ume of removed material and the time-resolved current of ejected ions were measured. These data were used to determine the ion fraction of ejected mat erial. The ion fractions provide direct evidence that the break point is du e to the laser-plasma interaction. This is confirmed by the speed distribut ions of the positive ions and from the integrated intensities of the low-sp eed ion component. (C) 2000 American Institute of Physics. [S0021-8979(00)0 4614-4].