FRANCK-CONDON RULES FOR PROBABILITIES OF TRANSITIONS BETWEEN RYDBERG LEVELS OF ATOMIC-HYDROGEN IN A MAGNETIC-FIELD

Transitions between highly excited quadratic Zeeman levels of atomic h ydrogen are considered. If the lower state is l-mixed, simple semiclas sical rules are shown to exist determining transitions with the larges t probabilities. These rules link the turning angles of oscillation of the Runge-Lenz vector of the atomic electron and (in the case of the irregular upper states) the direction of the periodic orbits of the el ectron at the moment when it passes through the nucleus. The Fourier t ransform of intensities of the Rydberg-Rydberg transitions in the magn etic field is investigated.