ATOMS AND IONS IN SUPERFLUID-HELIUM .1. OPTICAL-SPECTRA OF ATOMIC ANDIONIC IMPURITIES

Optical spectra of atomic impurities in liquid helium have been invest igated. Comparison is made between the wavelength of the free atomic a nd ionic lines and those in the liquid helium matrix. Simultaneously, the line width and a possible asymmetry is recorded. Presence and abse nce of radiative transitions depend on the species of the atom implant ed in the quantum fluid. The absence of any optical transitions from s tates lying as low as 1, 8 eV below the ionization limit will be expla ined in this paper.