Studies on the Delayed Fluorescence by Means of a Flash Technique

Abstract

It has been shown that the delayed and normal fluorescence can be measured accurately by a usual flash apparatus. Such measurements, combined with that of T–T absorption, have enlarged the potentiality of a flash technique to a large extent. As an example, a simple method of differentiation between E-type and P-type delayed fluorescence has been presented. Detailed studies have been made on the T–T annihilation process of anthracene (A) and the probability for Process A^T+A^T→A+A^*, has been decided. The value obtained is 0.077±0.005. E-Type delayed fluorescence of eosine and proflavine have been studied and the value of k_t·φ_ST (k_t, the rate constant of Process, T\ightharpoonupS^*; φ_ST, the probability of the intersystem crossing) have been evaluated, to be 3.3₆ and 2.7₈ sec⁻¹ respectively. Some advantages of the present method over the sector method have been discussed.