Experimental study of an abnormal optical resonance phenomenon in certain metals when in the form of thin layers: P. Rouard, Colloque sur l'optique des couches minces solides, Marseille, 8–15 Sept. 1963, J. Physique (in press)

Abstract

This chapter discusses the principal experimental techniques in the study of hyperfine interactions, such as the Hamiltonian for hyperfine interactions; hyperfine structure of one-electron atoms; and hyperfine structure of complex atoms and ions. The classical method is optical spectroscopy. Resolution of hyperfine structure in optical spectra has been improved significantly by the use of interferometers, such as the Fabry-Perot etalon, in place of diffraction gratings. Splittings as small as 0.005 cm-1 (∼ 100 Mc/sec) could theoretically be resolved by an interference spectrograph. In practice, however, atoms in the gas phase have linewidths determined by the Doppler effect, which are typically of the order of 0.1 cm-1 for light atoms to 0.01 cm-' for heavy atoms. Use of atomic beams, in which Doppler broadening is eliminated by observing atoms perpendicular to their line of flight, is required for the measurements of splittings finer than 0.01 cm-1. The most successful technique for the study of atomic hfs has been atomic beam magnetic resonance. Paramagnetic resonance of atoms in the gas phase3 and in inert matrices and of transition metal ions in solution and in crystals has also yielded useful data on hyperfine interactions. It must, however, be recognized that external interactions usually influence the observed hyperfine structure. The chapter mentions the optical polarization spin-exchange technique.