On the comparison of T1 and T2 as determined from zero-field and non-zero-field microwave measurements

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Abstract
The application of the recent theories of Liu and Marcus [J. Chem. Phys. 63, 272 (1975)] and Coombe and Snider [J. Chem. Phys. 67, 2659 (1977)] for the experimental determination of the relaxation parameters T1 and T2 from line shape measurements in zero Stark field is examined. In the first part of the paper it is shown that power‐broadened absorption lines in zero field may be fit to a single Lorentzian line shape from which a combined parameter qT1/T2 may be obtained. The new parameter q, which is determined by the distribution of populations of the m components of the levels under conditions of partial saturation, is defined and related to results of previous work. In the second part of the paper expressions for T1−1 and T2−1 for the zero‐field and non‐zero‐field cases are derived in terms of time correlation integrals of a random perturbation. It is shown that a close connection exists between T1−1u1 and T2−1 in zero field and certain averages of these quantities over the m states for nonzero field. From the comparisons it is seen that precise values of these parameters may provide additional information about the collision process.