The effect of velocity-changing collisions upon saturated-absorption profiles: the laser line of xenon at lambda =3.51μm

Parameters giving the broadening due to Xe perturbers of the laser line of xenon at lambda =3.51 mu m are obtained in linear absorption and compared with those found in saturated absorption. The results are found to differ significantly. Furthermore, the non-linear variation of the broadening constant with pressure observed in saturated absorption does not appear in linear absorption. The data can be explained by including the effects of weak velocity-changing collisions (VCC) upon saturated-absorption profiles. We show that under these conditions the width of the narrow resonance of saturated absorption is due mainly to the effects of weak VCC.