Abstract

Recently we have shown that the application of Fourier transform methods (and more specifically, the sine transform) to experiments of single-photon decay spectroscopy (SPDS) can be advantageous when the fluorescence intensity is low and the lifetimes to be measured are long (lifetimes longer than 1 μs are usually found in experiments of solid state physics). For monoexponential decays, the sine transform of the probability density of the time of arrival of the first fluorescence photoelectron presents a peak whose maximum corresponds to a value of the frequency equal to the inverse of the lifetime. The presence of this peak allows us to obtain the value of the lifetime with better accuracy than that obtained by means of the conventional multichannel technique. Because of the finiteness of the period of the excitation pulse chain, a periodic ripple appears superimposed to the main peak. Its influence increases as the period of the excitation signal decreases. For multi-exponential decays, this effect may mask some of the components if their fluorescence intensities are very low. In this paper we have studied the influence of the pulse repetition rate in SPDS experiments when sine transform methods are applied. As a first step, this study has been performed for monoexponential decays, and the optimum pulse repetition rate has been obtained. An experimental verification has been carried out by measuring the lifetime of the excited level ⁴T₁, of Mn²⁺ in a TMMC crystal.

© 1992 Optical Society of America