I Optical Pumping

Abstract

This chapter focuses on optical pumping, which is a method for producing important changes in the population distribution of atoms and ions among their energy states by optical irradiation. These population changes can be monitored by the change of intensity of the light transmitted by the sample in which optical pumping is produced or by the change of intensity or of polarization of the scattered resonance light. The methods of optical pumping and of optical detection can also be used, either together or separately to investigate excited states of atoms. The change of population produced by optical pumping is associated not only with a change of energy of the atomic assembly, but also with a peculiar change of angular momentum. By optical pumping, polarization of the spin vectors is produced, and macroscopic magnetization of the medium is obtained. The chapter states the principles of optical pumping and discusses the characteristics of the optical pumping methods. Optical pumping leads to a simple device to study radiofrequency resonance, to investigate Zeeman intervals and hyperfine intervals. It also leads to a systematic study of the interactions of atoms with electromagnetic fields in the optical range and in the radiofrequency range.