M dependence of T1 and T2 for the inversion doublets of 15NH3

Abstract
The pressure dependence of T1 and T2 has been measured for the ΔM=0, ‖M‖ inversion transitions in the (J=2,K=2) and (J=3,K=3) rotational states of 15NH3. We find the T2 is not M dependent but that T1 is strongly M dependent. These results are successfully interpreted by using a modified version of the Anderson impact theory which shows an M2 contribution to T1. The consequences of these results to other experiments are also considered.