Optical Pumping.

This experiment involves techniques and phenomena many of which were initially explored by members of the Columbia Physics department. Prof. I. I. Rabi and his colleagues, used R. F. spin flip techniques in atomic beam experiments. The “BreitRabi” formula used is from Phys. Rev. 38, 2082 (1931). The g factor for the electron spin is 2.0 vs. 1.0 for the orbital momentum in Dirac’s theory of the electron. The KushFoley studies (Phys. Rev. 72, 1256 (1947)) first established the anomalous value gs ≈ 2 0023 . for the electron spin. This, along with Columbia results of W. E. Lamb and Rutherford on the hydrogen fine structure, provided the theoretical stimulus for the development of Quantum Electrodynamics as it is today. Professors R. Novick, S. Hartmann, and W. Happer were active in developing the field of optical pumping.