Absorption and reshaping of 10.6 microns light in pure SF6 using 1.5 ns, low-intensity incident pulses

Results obtained in absorption measurements in pure SF6 in a low-pressure cell, using 1.5 ns, 10.6 micron light pulses are reported. Intensities up to 300 kW/sq cm of P(20) CO2 line with a Gaussian spatial profile and cells of different lengths have been used. Above an intensity-dependent value of product of pressure and length product, a reshaping and delay of the transmitted pulse are found, indicating the onset of self-induced transparency in the weak-field regime. Evidence for zero-area pulses is reported.