A UNIFIED SYSTEM FOR THE MEASUREMENT OF TRANSIENT PROPERTIES OF FLUORESCENCE BY COMBINING A SINGLE-PHOTON COUNTING TECHNIQUE AND A PERSONAL-COMPUTER

This paper reports a unified apparatus for measuring transient properties of fluorescence emission by using the single photon counting technique. The apparatus has the advantage of low cost and easy construction. The time-correlated single photon counting method was adopted for the measurement of fluorescence decay curves. A free running nanosecond light source was constructed, which consists of tungsten spark gap and sealed N2 gas. Fluorescence lifetimes were determined by the multiexponential fitting of observed decay data under consideration of convolution effects. Time-resolved fluorescence spectra can be measured with the same apparatus; A time analyzer works as a time gate, and output counts of the analyzer were stored on the memory of a personal computer. After scanning the observing wavelengths over a fluorescence band, a time-resolved fluorescence spectrum corresponding to a gated time was recorded on the memory of personal computer. Use of the memory of personal computer removes restriction on spectral range and reduces the cost to construct an apparatus. The performance of the apparatus was tested with the standard compounds of fluorescence lifetime and the accuracy of the system was found to be better than 0.2 ns.