Fluorescence‐Detected Low Field Resonances in T–T Annihilation in the A‐TCNB Single Crystal Lineshape and Dynamic Parameters

Abstract

AbstractAn investigation is made of the line shape of the low field resonances observed in the dependence of the fluorescence of a single A‐TCNB CT crystal on the external magnetic field. It is shown that the resonance is caused by avoided crossing of magnetic sublevels of a single T‐exciton arising when the direction of the field is close to the axis of the fine interaction tensor. An analytic expression for the resonance line shape is obtained. The spin–lattice relaxation rate of T‐excitons, τ−1 = (1.0 ± 0.3) × 107 s−1 as well as the rate of jumps between the planes of fast exciton migrations, ω1 = (5 ± 2) × 107 s−1, are determined.