OPTICAL SPECTROSCOPY OF ATOMS IN SUPERFLUID-HELIUM

Optical spectroscopy of impurity atoms and ions immersed into liquid h elium can contribute to the understanding of the structure of defects in helium and their interaction with the superfluid phase as well. Sin ce the theoretical understanding of the defect structure in liquid hel ium caused by alkali impurities is incomplete so far, spectroscopic st udies of these elements in the liquid helium environment are of consid erable interest. In this contribution measurements of the spectra of t he heavy alkali elements in superfluid helium are presented. The posit ion and the shape of excitation and emission lines of Rubidium is dete rmined by the use of a tunable diode laser.