COMPARISON OF SHORT-RANGE AND ASYMPTOTIC MEASUREMENTS OF THE KINETIC-ENERGY DISTRIBUTIONS OF LASER-ABLATED ALUMINUM ATOMS

We compare the kinetic energy distributions of ultraviolet excimer las er ablated A1 atoms measured within 1 cm of the metal surface by optic al transient absorption, to those measured over 20 cm from the surface by pulsed photoionization time-of-flight mass spectrometry. For the m ild ablation conditions used the distributions are the same. This resu lt demands the existence of a good one-to-one correspondence of atomic velocity to distance traveled from the ablated surface on the approxi mately 1 mus timescale of the short range measurement, suggesting that the duration of the A1 atom production period is less-than-or-equal 1 00 ns. This study establishes the viability of a novel concept for a c ompact velocity selection scheme for faster laser ablated neutral spec ies.