Optical spectroscopy of atoms in superfluid helium

Optical spectroscopy of impurity atoms and ions immersed into liquid helium can contribute to the understanding of the structure of defects in helium and their interaction with the superfluid phase as well. Since the theoretical understanding of the effect structure in liquid helium caused by alkali impurities is incomplete so far, spectroscopic studies of these elements in the liquid helium environment are of considerable interest. In this contribution measurements of the spectra of the heavy alkali elements in superfluid helium are presented. The position and the shape of excitation and emission lines of Rubidium is determined by the use of a tunable diode laser.