Velocity selection of fast laser ablated aluminum atoms by temporally and spatially specific photoionization

Abstract

The successful demonstration of velocity selection of fast aluminum atoms by a novel, nonmechanical technique is reported. Pulses of atoms with broad velocity distributions are produced by laser ablation of aluminum metal. A second pulsed laser, delayed by ∼1 μs and crossed at a right angle to the atomic beam, is used to photoionize only those atoms with unwanted velocities, i.e., atoms moving too fast or too slow to be hidden behind an opaque mask placed ∼1 cm from the ablated surface. The photoions are subsequently deflected from the beam by a static magnetic field. Velocity selected Al atom fluxes equivalent to Φ∼1011 atoms/(cm2 eV pulse) at a working distance of 10 cm are demonstrated.