Peculiarities of concentration quenching of Fe2+ luminescence in ZnSe single crystal

Time dependence of the luminescence power of the Fe²⁺ ion in ZnSe single crystal at liquid nitrogen temperature when excited by a short laser pulse of 2940 nm wavelength at various concentrations of Fe²⁺ ions and different pulse energy densities on the sample surface was studied. It is shown that the shape of the luminescence decay curve depends both on the Fe²⁺ concentration and the energy density of the laser pulse. Such behavior of the luminescence kinetics is interpreted as the manifestation of the concentration quenching of Fe²⁺ excited state. A theoretical description of the observed dependences is proposed, and the best agreement between the calculated and experimental curves is obtained if we assume that the probability of quenching per unit time is proportional to the square of the concentration of Fe²⁺ ions in excited state.