THE KERR-EFFECT IN HE, NE, H-2, AND N-2 AT ROOM-TEMPERATURE

We present measurements of the DC Kerr constant for He, Ne, H-2, and N -2 near 295 K. All measurements were made with a novel intracavity las er polarimeter and are accurate at the 1-2% level. We show, finally, t hat now there is consistency between the various experimental nonreson ant chi(3) measurements for these gases. For He and Ne we show that th e results are consistent with ab initio calculations at the 1% level. For H-2 and N-2 we show that the experiments are consistent with calcu lations based upon a polarizability model for the vibrational and rota tional contribution. We conclude that the full structure of chi(3) for nonresonant processes is now understood for dilute gases. For H, ther e is a minor disagreement between previously measured and our calculat ed temperature dependence of the molecular component.