Optimization of a Boxcar Integrator/Averager System for Excited-State Lifetime Measurements

Abstract

The instrumental distortions due to adjustable parameters of the SR250 boxcar integrator/averager system and a pulsed-laser luminescence spectrometer on the excited-state lifetime decay waveforms were investigated. A theoretical model which takes into account the exponential moving average for this instrument and also RC distortion on the time-dependent luminescence signal is presented. An analytical expression relating the sample's excited-state lifetime and the adjustable instrumental parameters such as laser repetition rate, gate scan time, gate width, scan width, number of samples averaged, and RC time constants from cables, termination, and other coupled instruments was obtained. Computer simulation using this expression was performed, and the good agreement found between the simulated and the experimental decay curves showed that the proposed mathematical equation can be applied to the optimization of instrumental parameters as well as in least-squares data reduction methods for luminescence kinetics measurements.