LASER WAVELENGTH DEPENDENCE OF YBA2CU3OY LASER-ABLATION PLUMES

The plume produced by laser ablation of an YBa2Cu3Oy target under irra diation with different laser beam wavelengths has been studied by mean s 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/cm(2). The investigation was carried out under high vacuum. The plume images show the evolution of different velocity components which depend on the la ser wavelength. The fastest one shows a front velocity near 10(4) m/s. It is the dominant feature during many mu s in the images obtained fo r 193 nm and can be also seen for the case of 532 nm. A slower emissio n, with an estimated velocity less than or equal to 3 X 10(2) 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 x 10(2) and 7 X 10(2) m/s fo r 532 and 1064 nm laser wavelength, respectively. The velocity of the other one is estimated as less than or equal to 10(2) m/s.