Vacuum UV luminescence excitation spectra in CaF2 crystals doped with rare-earth elements

Excitation spectra of eigen (exiton) and activator luminescence of CaF2 crystals containing 0.1% Ce3+, Eu3+ or Dy3+ are investigated at 300 K within 5-27 eV range. Luminescence of eigen localized exciton is effectively excited in the hν=10-12 eV in CaF2. Electron hole pairs exciting recombination luminescence of the activators (for Eusup(2+) captured) according to the monomolecular mechanism are formed at hν > 12 eV. At hν > 23 eV one photon begins to generate more than one electron excitation due to which excitation efficiencies of both exiton and admixture luminescences increase