Effect of pulse duration and polarization on momentum and energy transfer to laser-irradiated targets

Polished aluminum targets were irradiated with 1.06m laser pulses of 60-psec and 2.5-nsec duration and of and 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.