IMPLANTATION AND SPECTROSCOPY OF METAL ATOMS IN SOLID HELIUM

The first implantation of neutral Ba and Cs atoms into solid He-4 is r eported. We discuss details of the experimental setup and techniques u sed to load the helium with atoms at concentrations of 10(8) cm(-3). I f photodissociation of Cs molecules and clusters is performed twice pe r hour this atomic concentration can be kept without a second implanta tion for almost a clay. From the optical spectra of Ba in solid helium we infer no significant difference in the trapping site with respect to that in liquid helium.