Error analysis of the rapid lifetime determination method for double-exponential decays and new windowing schemes

The rapid lifetime determination method (RLD) is a mathematical technique f or extremely rapid evaluations of lifetimes in exponential decays, It has b een applied in luminescence microscopy and single-molecule lifetime evaluat ion. To date, the primary application has been in single-exponential evalua tions. We present extensions of the method to double exponentials, Using Mo nte Carlo simulations, we assess the performance of both the double-exponen tial decay with known lifetimes and the double-exponential decay with unkno wn preexponential factors and lifetimes. Precision is evaluated as a functi on of the noise level (Poisson statistics), the ratios of the lifetimes, th e ratios of their preexponential factors, and the fitting window. Optimum m easurement conditions are determined. RLD is shown to work well over a wide range of practical experimental conditions. If the lifetimes are known, th e preexponential factors can be determined with good precision even at low total counts (10(4)), With unknown preexponential factors and lifetimes, pr ecisions decrease but are still acceptable. A new gating scheme (overlapped gating) is shown to offer improved precision for the case of a single-expo nential decay, Theoretical predictions are tested against actual experiment al data from a laser-based lifetime instrument.