Studies of Laser Ablation of Solid Samples and its Plasma Formation.

Laser ablation of solid samples has been studied since the development of the ruby laser. The metallic sample is vaporized and excited by absorption of an intensive laser radiation. The vaporization or ablation depends on laser parameters and certain physical characteristics of the sample. Theoretical studies have been limited to a few materials and no analytical solution has been known for quantitative predictions. A theoretical model was established to relate the mass ablated to the laser irradiance in terms of the thermal properties of the metal. To better understand the breakdown phenomenon, it is essential to investigate the development and propagation of the metal vapor plasma. Space and time resolved spectrometric studies were carried out. Results obtained indicate that the plasma, created on four different metal targets by an excimer laser with a wavelength of 193 nm and laser energy of 150 to 200 mJ, has a near gaussian distribution, and the plasma emission has a peak maximum at 20 mus and prolongs to about 100 mus.