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 YBa 2 Cu 3 O y , using a space/time-resolved optical transmittance measurement. The average velocities of the nonradiative fragments (2×10 5 cm/s and 2×10 4 cm/s) are much lower than those of the radiative fragments (5×10 6 cm/s and 1×10 6 cm/s). The yield of the nonradiative fragments increases with increasing laser wavelength, while that of the radiative fragments is nearly wavelength independent.