Time-delayed photoelectric effect

Abstract

The Einstein photoelectric relation¹ initially explained the photoelectric effect,

hν=T_max + E_b

where hν is the energy of a photon incident on a material, E_b is the binding energy of the electron to be excited, and T_max is the maximum kinetic energy of the emitted electron. This work has generated considerable research^2–5 because of its multidisciplinary interest. We describe here photoelectric emission (PE) experiments using very low-intensity nanosecond light pulses with energies near the PE threshold. Signal correlated, time-delayed pulses of emitted electrons were observed for single light pulses incident on a photosensitive material. However, the energies of the delayed emitted electrons were not correlated to the wavelength of the incident light, which is not consistent with Einstein's relation. At higher incident light intensities, the delayed pulses were not observed. These pulses were not due to electrical noise because they disappeared when the laser light was blocked from entering the cell. They were not due to single photon luminescence from a particular species because the pulses were observed using another experimental apparatus with an alternate source of nanosecond light. We now describe these delayed pulses and give a preliminary interpretation of them.