A New Technique to Study Rydberg States by Multiphoton Ionization Spectroscopy

A new technique to study the Rydberg states of the Ba atom has been developed. In this technique a Multiphoton Ionization signal is detected by selective excitation of the ground state ion (6s) to an excited state (6p), which results in a collimated Amplified Spontaneous Emission (ASE) signal at the 6p+5d transition of Ba'. Discrete Rydberg states, 6snL (k=0,2), as well as autoionizing Rydberg states, 5dnk (!2=0,2) and 6pnll (11=0,2) are observed by this novel but very simple method.