VELOCITY SELECTION OF FAST LASER-ABLATED ALUMINUM ATOMS BY TEMPORALLYAND SPATIALLY SPECIFIC PHOTOIONIZATION

The successful demonstration of velocity selection of fast aluminum at oms by a novel, nonmechanical technique is reported. Pulses of atoms w ith broad velocity distributions are produced by laser ablation of alu minum metal. A second pulsed laser, delayed by similar to 1 mu s and c rossed at a right angle to the atomic beam, is used to photoionize onl y those atoms with unwanted velocities, i.e., atoms moving too fast or too slow to be hidden behind an opaque mask placed similar to 1 cm fr om the ablated surface. The photoions are subsequently deflected from the beam by a static magnetic field. Velocity selected Al atom fluxes equivalent to Phi similar to 10(11) atoms/(cm(2) eV pulse) at a workin g distance of 10 cm are demonstrated. (c) 1994 American Institute of P hysics.