Fluctuation correlation spectroscopy for the advanced physics laboratory

A fluorescence correlation spectrometer is developed that is suitable for use in advanced laboratory courses. The instrument is simple to build and understand and can be constructed at a small fraction of the cost of a commercial or research-grade instrument. We demonstrate its surprisingly high performance with a simple biophysics application, the study of the binding of two complementary DNA strands. The instrument will be useful in areas of physics where precise measurements of the dynamics of fluorescent (or fluorescently labeled) molecules or nanoparticles in solution are of interest. (c) 2005 American Association of Physics Teachers.