Optical resonance detection by field ionization of Rydberg state in colinear laser spectroscopy

2014 New efficient non-optical detection methods of optical resonances in colinear laser spectroscopy are described. A first method uses the field ionization of a Rydberg state populated by means of two lasers : one is single frequency and interacts colinearly with the fast atomic beam, the other one is multimode and interacts perpendicularly. By detecting, at resonance, the produced ions instead of the fluorescence photons, an overall efficiency of 1.1 x 10-5 has been obtained, which is comparable to the usual sensitivity limit reached by the laser induced fluorescence method. A second similar experiment uses two single mode dye lasers both interacting colinearly with the fast atomic beam. Compared to the first technique an increase of the sensitivity by two orders of magnitude has been obtained (corresponding to an efficiency of 1.2 x 103). Application to the study of on line produced short-lived isotopes is discussed. J. Physique 47 (1986) 1167-1173 JUILLET 1986,