Percolation and emission spectra of a laser plasma upon ablation of silicon and silicon-containing composites

The emission spectra of plasmas produced near the surface of silicon and sulphur samples and their mixtures by nanosecond and millisecond laser pulses are studied in a broad range of pressures of buffer gases. The percolation dependences are obtained for composite Si–S, Si–SiO₂, and SiO₂–S targets. It is found that experimental percolation thresholds coincide with the typical threshold for three-dimensional continual percolation.