Photoelectroluminescence of Single Crystals of Manganese‐Activated Zinc Sulfide

Photoelectroluminescence, which involves the control of electroluminescence by electromagnetic radiation, is reported for single crystals of manganese-activated zinc sulfide. Both plane-parallel and point-contact electrode structures were used. The latter resulted in greater homogeneity of luminescent emission with the applied voltage mainly across the spreading resistance regions. The field distribution was probed. The observations are explained with essentially the same basic theory as was earlier used to explain observations on vapor-deposited films. However, from the analysis of the data on single crystals we deduce that carrier multiplication is occurring in the cathode region and to a lesser extent in the anode region, and also obtain values for the local fields for acceleration of carriers and for collision excitation. © 1966 The American Institute of Physics

A world population growth model: Interaction with Earth's carrying capacity and technology in limited space

Up to 1900, world population growth over 1500 years fitted the quasi-hyperbolic format P(t) = a/(D-t)M, but this fit projected to infinite population around 2000. The recent slowdown has been fitted only by iteration of differential equations. This study fits the mean world population estimates from CE 400 to present with "tamed quasi-hyperbolic function" P(t) = A/[ln(B + e(D-t)//τ)]M, which reverts to P = a/(D-t)M when t ≤D. With coefficient values P(t) = 3.83 × 109/[ln(1.28 + e(1980-t)/22.9)]0.70, the fit is within ±9%, except in 1200-1400, and projects to a plateau at 10.2 billion. An interaction model of Earth's carrying capacity and technological-organizational skills is proposed. It can be approximately fitted with this P(t) and an analogous equation for carrying capacity. © 2013 Elsevier Inc