Effect of Pulse Duration and Polarization on Momentum and Energy Transfer to Laser-Irradiated Targets

Polished aluminum targets were irradiated with 1.06-{μ}m laser pulses of 60-psec and 2.5-nsec duration and of π and σ polarization. The peak focused intensity was varied over the range 10¹⁴-10¹⁶W/cm². Clear evidence of resonant absorption for 60-psec pulses was obtained from target momentum measurements made with a torsion pendulum. No resonant absorption effects dependent on light polarization or angle of incidence were detected for long-pulse irradiations.