Fluorometric Data Processing Strategies Using Nanosecond Waveform Digitizers

Abstract

Developments in commercially available digitization technology have made practical the software processing of nanosecond fluorometric data. The data are digitized and transferred to a microcomputer after each excitation pulse, then processed by a software module simulating either analog or photon counting detection. Software anode current processing provides display of the decay and integration of its area in the same operation, offers a multiplex advantage to improve decay collection rate, and allows the definition of a nearly rectangular gating function with sharp 1-ns edges. Application of the photon counting method to fluorometric instruments based on low-repetition-rate lasers is achieved with a multistop, multilevel discrimination algorithm to increase the usable detection rate. The ability to achieve photon counting detection permits a more rigorous statistical treatment of the data and can provide transit time-spread limited resolution.