ANISOTROPIC OPTICAL-SPECTRA OF YALO3 (YAP) SINGLE-CRYSTALS IN THE VACUUM-ULTRAVIOLET REGION .3. SPECTRA OF OPTICAL-CONSTANTS

The Kramers-Kronig derived complex dielectric constant, energy loss functions and effective number of electrons of YAP are presented in the region of 6 eV approximately 120 eV for the light polarized parallel to each of the three crystallographic axes. The peak value of epsilon2 spectrum at 33.34 eV, the highest-energy component of the bands associated with five resonance transitions from the Y3+ 4p6 level, is found to be proportional to the site number of Y3+/cm3 in the lattices of YAG, YAP and Y2O3. The maxima due to plasma oscillations are derived at approximately 23 eV and approximately 36 eV in each volume loss function. The energy dependence of the dielectric constant is found to be in substantial agreement in the region of 50 eV approximately 120 eV with that calculated by the Drude formula with the use of the peak energy and half value width of the loss maximum at approximately 36 eV. The above continuum is superposed on the features led by doublet lines at 78.4 eV and 78.8 eV which originate from the transitions from the Al3+L2,3 levels.