Methods for optical detection of electron spin coherence in nonphosphorescent triplet states

Abstract

A method is described whereby the time development of the coherent components within the spin sublevels of an excited triplet state can be monitored, using an observable which can measure only the total population of the sublevel manifold, such as absorbance to higher triplet states or singlet fluorescence. The approach is very similar to the ’’probe’’ pulse method recently developed for the optical detection of electron spin coherence in phosphorescent triplet states, but the procedure for extracting the value of the coherent component is different. In the present approach it is shown that the recovery of the total population of the sublevel manifold to steady state, after the pulse sequence has been applied, is sensitive to the coherence. By measuring the amplitude of the recovery curve as a function of pulse timing the lifetime of the coherent component can be obtained. Application of the method to some common coherence experiments is discussed.