Angle-resolved time-of-flight spectrometry of neutrals laser ablated from Nd1.85Ce0.15CuO4

Abstract

Angle-resolved time-of-flight (ARTOF) distributions of O, Cu, and Nd atoms and of NdO molecules ablated from the alloy Nd1.85Ce0.15CuO4 were measured with a quadrupole mass spectrometer. From these distributions angle-resolved yield (ARY) distributions of the neutrals were obtained. The most probable kinetic energy was irrespective of the type of neutral approximately 2.3 eV. The experimental ARTOF spectra were fitted quite well with theoretical Maxwell–Boltzmann (FMB) distributions superimposed onto angle-dependent flow-velocity contributions. The temperatures and Mach numbers associated with these fits were about 1.20×103 K and 4.9, respectively, irrespective of the type of atom considered. The experimental ARY distributions were fitted with cosp θ distributions, where p≊6. This p value was much lower than expected from the FMB distributions. The results are discussed in terms of explosive surface evaporation followed by collisional modification in the ablation-induced plasmas of the nascent ARTOF and ARY distributions and in terms of explosive volume evaporation. Additional contributions to the experimental ARTOF and ARY distributions with respect to the fits are ascribed to additional thermal mechanisms.