Laser wavelength dependence of YBa2Cu3Oy laser ablation plumes

The plume produced by laser ablation of an YBa2Cu3Oy target under irradiation with different laser beam wavelengths has been studied by means of intensified CCD imaging. ArF excimer (193 nm) and Nd:YAG (532 and 1064 nm) laser beams were used. The fluence was about 1 J/cm2. The investigation was carried out under high vacuum. The plume images show the evolution of different velocity components which depend on the laser wavelength. The fastest one shows a front velocity near 104 m/s. It is the dominant feature during many μs in the images obtained for 193 nm and can be also seen for the case of 532 nm. A slower emission, with an estimated velocity ≤ 3 × 102 m/s, can also be observed for the case of 193 nm laser irradiation. Two slower velocity components are present in the 532 and 1064 nm laser plumes. One of them has a front velocity around 3 × 102 and 7 × 102 m/s for 532 and 1064 nm laser wavelength, respectively. The velocity of the other one is estimated as ≤ 102 m/s.