Strong wavelength dependence of laser ablation fragments of superconductor YBa2Cu3Oy

In addition to the two groups of radiative fragments which have previously been described, two groups of nonradiative fragments are first observed in laser-ablated fragments of YBa2Cu3Oy, using a space/time-resolved optical transmittance measurement. The average velocities of the nonradiative fragments (2×105 cm/s and 2×104 cm/s) are much lower than those of the radiative fragments (5×106 cm/s and 1×106 cm/s). The yield of the nonradiative fragments increases with increasing laser wavelength, while that of the radiative fragments is nearly wavelength independent.