title: Optical detection of nonradiating alkali atoms in solid helium.
abstract: We have detected by optical means nonfluorescing 85Rb and 87Rb atoms implanted in a body centered cubic 4He crystal. In contrast to cesium the resonance fluorescence of rubidium is strongly quenched by the helium matrix, and the weak resonance absorption of the two Rb isotopes was detected using a double resonance technique. From a comparative study of the (optically detected) magnetic resonance spectra of 85Rb, 87Rb, and 133Cs we infer their effective g(F) factors and conclude that they are not perturbed by the He matrix at a level of 2 x 10(-4). We show further that optical pumping of Rb proceeds via depopulation, whereas for Cs it proceeds via repopulation.
authors.affiliation: Département de Physique, Université de Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Eichler
authors.forename: R
authors.initials: R
authors.lastname: Müller-Siebert
authors.forename: D
authors.initials: D
authors.lastname: Nettels
authors.forename: S
authors.initials: S
authors.lastname: Kanorsky
authors.forename: A
authors.initials: A
authors.lastname: Weis