FLUOROMETRIC DATA-PROCESSING STRATEGIES USING NANOSECOND WAVE-FORM DIGITIZERS

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.