Laser-produced plasma dynamics during ablation of gold, silver and aluminum using nanosecond pulses
Abstract
We report an experimental investigation of laser-induced plasmas of gold, silver, and aluminum. Pulses with a duration of 10 ns from an Nd:YAG laser and energies up to 160 mJ were used to create laser plasma plumes inside a vacuum chamber. The spatial dynamics of the laser-induced plumes was recorded using a gated intensified charge-coupled device camera, which allowed the study of the expansion velocity of the emitting plasma plume with nanosecond resolution. The calculated velocities were found to be in good agreement with the atomic masses of the samples. The velocity of the lightest Al plasma plume was estimated to be 8.6 × 10^4 m/s, while for the heaviest sample, Au, the velocity was found to be 2.1 × 10^4 m/s. Based on the spatial measurements, a simple yet effective method was proposed and experimentally confirmed, which allows reducing the contribution of continuum emission to the plasma spectrum. Placing a thin metal blade into the optical path between the laser plume and the spectrometer allows an effective reduction of continuum emission in the integrated spectra and increases the contrast of characteristic spectral lines.