Mechanism and fading characteristics of photostimulated luminescence in imaging plate

The fading characteristics and optical bleaching of the electron traps such as F(F-), F(Br-) and F(I-) centers which are produced by X-ray irradiation are studied. Five kinds of the IP (imaging plate) (Fuji Photofilm) such as BAS-3, BAS-MS, BAS-ND, BAS-SR and BAS-TR were used as the samples. The samples were irradiated by X-rays from Cu-target tube operated at 40 kV and 20 mA. PSL (photostimulated luminescence) emission spectra and its stimulation spectra of samples were obtained. The experiments results showed the followings; 1) the fading of the X-ray image is remarkable in the longer wavelength, especially in the optical absorption band of the F(I-) centers, 2) a part of electrons which are thermally or optically released from the electron traps centers such as F(Br-) and F(I-) centers are retrapped by the F(F-) vacancies to produce the F(F-) centers. (S.Y.)