Analysis of fluorescence decay by the nonlinear least squares method.

Fluorescence decay deconvolution analysis to fit a multiexponential function by the nonlinear least squares method requires numerical calculation of a convolution integral. A linear approximation of the successive data of the instrument response function is proposed for the computation of the convolution integral. Deconvolution analysis of simulated fluorescence data were carried out to show that the linear approximation method is generally better when one of the lifetimes is comparable to the time interval between data.