Laser ablation studies of palladium electrolytically loaded with hydrogen and deuterium

The kinetic-energy distributions (KED's) of Pd+, Hn+, Dn+ (n=1 to 3), and electrons created in a picosecond laser-produced plasma from palladium metal were studied using a spherical-sector electrostatic energy analyzer followed by a time-of-flight mass spectrometer. High-resolution, Fourier-transform mass spectroscopy showed no PdHn+ or PdDn+ ions. The total yield of Pd+ ions grew linearly with laser power, while the yields of H+ and D+ increased exponentially. The yields of H2+ and H3+ increased with laser power density slowly, comparable to the yields of H+ and D+ at low laser power density only. The average ion kinetic energy was a linear function of laser power for all species, but with a much higher average kinetic energy for Pd+ than for other species at a given laser power. The KED's for Pd+ were dominated by a plasma component with a Maxwellian shape, accompanied by a thermionic component with a kinetic energy in the range of 0--1 eV. The H+, H2+, H3+, and D+ KED's were basically Maxwellian, but the origins were offset to positive kinetic energies, with the offset energy increasing linearly with mass. There was no thermal component for the Hn+ or D+ ions