Detection of Yb impurities in the VUV spectral range of NdGaO3 crystals

Substantial influence of the 1 at.% Yb doping of NdGaO₃ single crystals on the optical functions ε₁(E) and ε₂(E) in the spectral range of electronic excitations is established. The corresponding differences of the optical functions for pure and doped NdGaO₃ have been monitored using spectroscopic ellipsometry method and synchrotron radiation light source. This opens an opportunity for the spectroscopic diagnostics of the rare earth dopants in crystals using the spectroscopic information concerning the electronic inter-band optical transitions. To understand better the experimental results obtained, the ab-initio calculations of band structure and optical spectra of the centrosymmetric single crystal NdGaO₃ have been performed using the VASP code (Vienna Ab-initio Simulation Package). The calculated dielectric functions ε₁(E) and ε₂(E) agree satisfactorily with our experimental results obtained with using the spectroscopic ellipsometry method and synchrotron radiation. It was demonstrated that differences of the optical functions for pure and doped crystals using stable synchrotron source may serve as a powerful tool for spectroscopic diagnostic of localised rare earth ions with respect to the strong inter-band transitions.