Origin of the 420 nm absorption band in PbWO₄single crystals

Abstract

Single crystals of PbW04 (PWO) are intensively studied in the last few years in connection with their potential application for scintillation detectors in high energy physics [I, 21. Within the last year a dramatic increase of this research activity has been observed [3] in connection with the planned construction of a PWO-based electromagnetic calorimeter in the accelerator ring at CERN. The emission spectrum of PWO consists of two main componentsthe blue one peaking at about 420 nm and the green one peaking at about 480 to 510 nm. While the blue component is ascribed to the regular lattice centres (w04)2-[4], the green one is related to the WOs centres [ 5 ] , i.e. it depends on the oxygen non-stoichiometry in the crystal and on the concentration of accidental impurities as well. Variable oxygen defi-') Cukrovarnicka 10, CZ-16200 Prague, Czech Republic. *) Rudower Chaussee 6,

Contribution of structural order-disorder to the green photoluminescence ofPbWO4

“…4,6,10,[16][17][18][19] Nevertheless, the understanding of PWO spectral behavior is still debated and some problems are left unsolved. [20][21][22][23] For example, numerous experimental works directed at identifying several types of defects and their spectral roles in PWO have recently been published. [24][25][26][27][28][29] Particularly, there are discussions 30,31 over the contribution of color centers to the photoluminescence ͑PL͒ emission band, mainly to the green emission band.…”

Growth of trivalent ions doped PbWO4 crystals and their scintillation properties

“…O -and Pb 3+ are formed in order to compensate the charge balance. It was put forward that O -and Pb 3+ result in the 420nm absorption [9,15]. M 3+ ions predominantly replace V Pb , which suppresses the defects formation of O -and Pb 3+ .…”

Luminescence properties of annealed PbWO 4 single crystals

“…The 420 nm OA band has been ascribed to either O -or Pb 3+ centers [12]. OA spectra of PWO annealed at temperatures below 700 o C are nearly identical to those of as-grown PWO.…”