Laser-rf Double-Resonance Spectroscopy

Abstract

Although optical-microwave and optical-rf double-resonance experiments have been performed for many years now, perhaps the first such experiment to use a single-frequency, tunable dye laser as the source of the optical photons was that of R. W. Field, et al. [1], who examined the molecular structure of Ba0 vapor in 1973. Double resonance was detected as microwave-dependent changes in the laser-induced fluorescence of the vapor. The idea of substituting laser fields for the A and B magnets of a conventional Rabi atomic-beam magnetic-resonance apparatus had occurred early in the laser era to many people, and its feasibility was demonstrated by Schieder and Walther [2] in 1974. The first actual observation with this arrangement of the laser-rf double-resonance technique was carried out by Rosner, Holt and Gaily [3] in 1975 on a molecular beam of Na₂. The technique was applied independently by Ertmer and Hofer [4], the same year, to investigate the hyperfine structure (hfs) of metastable levels of ⁴⁵Sc in a collimated atomic beam.