ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
We describe a digital cross-correlation instrument that employs a radio-frequency mixer and a radionuclide-scintillation light source to measure fluorescence lifetimes. The digital approach provides single-photon sensitivity and accurate lifetime analysis even at low sample concentrations. The unique characteristics of the scintillation excitation source, coupled with the simplicity of mixer-based signal processing, give this approach particular appeal over traditional instrumentation used for excited-state decay measurements. We discuss the system design and evaluate its performance using two optical configurations. The close-packed configuration provides an indication of the general fluorescence detection limits which can be expected from measurements made with scintillation-based light sources. After applying a procedure to correct for systematic error caused by the mixer diode-bias potential, the results from the digital system demonstrate lifetime accuracy over a range of sample concentrations (nM–mM). Finally, we develop a modified detection sensitivity parameter and calculate its value to be 1×10−3 s photon−1 pathlength−1 for our experiments. This new parameter can assist in the design of other scintillation-based lifetime measuring devices. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1148815
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