The metastable Ne(

The fluorescence excitation spectra of metastable3 P2 Ne atoms in superfluid helium have been studied for the first time. Ne spectral lines show a surprisingly small broadening and shift. We have also studied emission spectra and decay times related to the strongly forbidden N(2D → 4S) transition in the impurity-helium solid phase (IHSP) containing metastable N atoms, N2 molecules and - in some cases - rare gas atoms (Rg = Ne or Kr). We have shown that the central cores of solid He clusters correspond to single metastable N*(2D) atoms or to N*-N2 and N*-Rg pairs as well as to triple N*-N2-Rg and exciton-like N*Rgn complexes, as evidenced by their luminescence spectra