The time-resolved photon-counting fluorometer at the National Synchrotron Light Source.

Abstract

AbstractA single‐photon‐counting fluorometer, capable of steady‐state and time‐dependent measure‐ments, is now operational at port U9B of the National Synchrotron Light Source at Brookhaven National Laboratory. Excitation wavelengths are selected by a prism‐grating double monochromator. Emission energies are chosen by filter(s) or by a one‐meter Spex monochromator. Commercial electronics are used for data acquisition, except for special circuitry required by the high (53 MHz) repetition rate of the synchrotron. A large sample chamber allows flexibility in arranging optical components and samples. The standard optical configuration of the sample chamber consists of a focusing mirror, a six position excitation optic wheel, a turntable with four thermostatted cuvette holders, a six position emission optic wheel, and an f/0.7 emission collection lens. Data acquisition and the setting of correct wavelengths and sample chamber optics are controlled by a Tektronix 4052 computer via the IEEE‐488 General Purpose Interface Bus. Time‐dependent fluorescence data are transferred to a VAX 11/730 for analysis; current deconvolution software includes nonlinear least‐squares programs for single curve and global analysis.