Effects of Magnetic and Electric Fields on Highly Excited Atoms

Abstract

The long and glittering history of the study of atoms in external electric and magnetic fields dates from the late 19th century work of Zeeman(1) and the early 20th century works of Stark(2) and Paschen and Back.(3) The birth of quantum mechanics was followed by the pioneering studies of diamagnetic effects of Van Vleck(4) and Jenkins and Segre,(5) and by the prediction of Landau resonances(6) in free-electron spectra of solids. More recently, observations of highly excited atoms in external fields, (7–10) made possible by the advent of high-resolution spectrometers, superconducting magnets, and lasers, have led to a revitalization of atomic spectroscopy. In particular, the observation of field-induced resonances in an otherwise smooth continuum(11–13) has compelled theory(14–16) to deal with a class of phenomena involving competing forces of different symmetries and comparable magnitudes. Fragmentary advances of theoretical understanding have in turn pointed to possibilities of using external fields as probes of atomic structure.