Notes on Intensities of Radiofrequency Spectra

In order to compare theoretical and observed line shapes of radiofrequency spectra, one must take account of the inhomogeneity in velocity of the beam molecules. The theoretical expression for line shape is integrated over the velocity distribution in the beam and the result is expressed in terms of integrals studied by Zahn and Laporte. The important parameters in the theory of line shapes are the matrix elements of the interaction with the radiation field. These are evaluated in the case of atoms with electronic angular momentum $J=\frac{1}{2}\hslash$ and arbitrary nuclear spin.