Optical properties of Pr3+ in lanthanum double molybdates and tungstates: KLa1-xPrx(MO4)(2) (M = Mo, W; x <= 1)

Absorption, emission and excitation spectra of diluted single crystals of K La1-xPrx(MO4)(2) (M = Mo, W; x less than or equal to 1) were measured. The intensities of the electronic transitions were analysed and related to the data of pure compounds. The fine structure of the electronic levels appeari ng in the optical spectra of the crystals is discussed. The temperature and concentration effects on intensities and the shapes of the observed bands are considered. Distinct vibronic sidebands were observed in the absorption , emission and excitation spectra for both systems. An assignment of the vi bronic transitions is proposed and the single ion relaxation processes and the cooperative interaction are discussed. (C) 1999 Elsevier Science B.V. A ll rights reserved.