OVERVIEW OF LASER-RADIOFREQUENCY DOUBLE-RESONANCE STUDIES OF ATOMIC, MOLECULAR, AND IONIC BEAMS

The molecular-beam laser-rf double-resonance method, first demonstrated about 15 years ago, has been used extensively in the years since to study properties of many electronic levels of both neutral and ionic atoms and molecules. The technique affords high precision (typically 1 ppm for hyperfine structure measurements), very high selectivity, and high sensitivity. In addition to revealing a wealth of details concerning hyperfine interactions, the method, when applied to molecules, allows precise measurement of rotational structure and electric-dipole moments (through the Stark effect). In applying the method to studies of the analogous properties of atomic and molecular ions, arranging the ion and laser beams colinearly is usually advantageous and much work has been done in this area as well. This review illustrates the types of results achieved so far. The extent of agreement between theory and experiment and the impact of the method on the further development of the theory are discussed more briefly. The conclusion attempts to suggest profitable areas for further exploration.