Preferential vaporization during laser ablation at the threshold of brass in air

In the present work we have studied the laser ablation of brass in air ambient at and above the ablation threshold. Photothermal deflection technique is used for determining the ablation threshold of brass. The technique is essentially based on measuring the deflection in the optical (probe) beam due to the gradient in refractive index close to the target surface produced by the pulsed (pump) laser beam. The deflection in the probe beam is slightly different below and above the ablation threshold. The experimentally obtained ablation threshold of brass is 3.1 J/cm(2) which is in well agreement with the theoretically calculated value of 3 J/cm(2). We have shown the preferential vaporization of Zn at the threshold in brass ablation. As we move above the threshold the intensity of Zn lines decreases and Cu lines increases. This work is applicable to the elemental analysis in the ablation process and segregation of elemental particles in thin film deposition.