Radiation Quenching of Radio- and Radiothermo-Luminescence of ZnS Phosphors, I. Luminescent Process under Excitation

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Spectra and buildup-decay curves of the luminescence of ZnS:Cu:Cl phosphors under excitation by 5.5 Mev electrons from a linear accelerator or β-rays of Sr⁹⁰–Y⁹⁰ were compared with those by near uv light. It was found that the ratio of the blue intensity to green one in the spectra of radioluminesence is markedly reduced from that of uv-luminescence. The intensity of uv-luminescence increases with the concentration of Cu up to 0.1% while that of β-luminescence begins to decrease at concentrations more than 0.02%. The normalized deficiency area of buildup curves of β-luminescence is greater than that of uv-luminescence for several phosphors but inverse for others. The results are interpreted as radiation quenching by assuming the production and migration of energetic energy carriers to cause the quenching. A localized transport process in a region along the path of incident electron was proposed to be probable.