Abstract

The paper presents the results of a study of the build-up and decay of some 200 samples of silicate, tungstate, molybdate and sulphide phosphors, excited by Hg 2536A radiation. The normal silicates decay at first exponentially, with a time constant of the order of 10⁻² sec. This initial rate is independent of the intensity and the duration of the excitation, and varies little among different samples of a given class (e.g., Zn₂SiO₄·Mn). The later decay is slower, and does vary markedly from sample to sample, and depends on the intensity and duration of the excitation. CaWO₄ decays too rapidly to be measured with the apparatus used (<50 microseconds); the decay of MgWO₄ lasts about 2×10⁻⁴ sec.; both these tungstates show a very faint long phosphorescence which can be enhanced slightly by addition of impurities. The red luminescence contributed by Sm in these and other “pure” phosphors decays exponentially with a time constant of about 7×10⁻⁴ sec. Sulphides have complicated decay characteristics, dependent on the intensity and duration of the excitation. Comparison is made with the results of a study of decay after electron bombardment, and with other published data.

© 1939 Optical Society of America

Luminescence of Sulphide and Silicate Phosphors

R. P. Johnson
J. Opt. Soc. Am. 29(9) 387-391 (1939)

Measurement of Activation and Decay of Luminescent Zinc Silicate

N. C. Beese
J. Opt. Soc. Am. 29(1) 26-28 (1939)

The Response of Several Fluorescent Materials to Short Wave-Length Ultraviolet Radiations

N. C. Beese
J. Opt. Soc. Am. 29(7) 278-282 (1939)

The Effect of Temperature and Exposure to X-Rays Upon Triboluminescence

Frances G. Wick
J. Opt. Soc. Am. 29(10) 407-412 (1939)

An Automatic Recording Spectroradiometer for Cathodoluminescent Materials*

V. K. Zworykin
J. Opt. Soc. Am. 29(2) 84-91 (1939)