The decay of the light emitted from several electroluminescent phosphors excited by periodically repeated voltage pulses of from 40 to 2500 microseconds duration has been determined. The slopes of the decay curves after each individual pulse excitation become steeper as the pulse duration decreases. The heights of the luminescence peaks excited at the leading and trailing edges of the pulses also depend on the pulse time. The results are interpreted as confirming previous conclusions about the influence of polarization charges. Numerical evaluation yields the correct order of magnitude for the "critical time" needed for the accumulation of polarization charges.

• Received 2 February 1955

DOI:https://doi.org/10.1103/PhysRev.99.1100