Nature of the Inhomogeneous Broadening of Optical Spectra in Eu3+doped Y2O3Crystals Studied by Optical-RF Double Resonance

Abstract

The nature of the inhomogeneous broadening of optical spectra has been investigated for Eu 3+ ions embedded in pure and impurity ion (Sc 3+ or Zr 4+ ) doped Y 2 O 3 crystals. High-resolution absorption spectra of the 7 F 0 – 5 D 0 transitions have been taken as excitation spectra of luminescence. Using optical-radio-frequency (rf) double resonance technique, the distribution of two hyperfine transitions (ω 1 : I z =±1/2 to ±3/2 and ω 2 : I z =±3/2 to ±5/2) in the 7 F 0 ground state were measured as a function of the optical excitation energy and displayed as a 2-dimensional map on the optical and rf axes. Thus the ionic sites are labeled by three parameters and some new sites were distinguished by using both ω 1 and ω 2 . The single crystals with a disorder systematically controlled by doping of various ions (Sc 3+ and Zr 4+ ) were investigated and the character of the inhomogeneous distribution was found to be strongly dependent on the doped ions. By applying the mapping method to the Sc 3+ doped Y 2 O 3 , the individual sites are discriminated inside the inhomogeneously broadened optical spectra, while the discrete peaks coalesce into a single broad peak in the optical spectrum at higher concentration.