Single photon fluorometer

Figure 12.3. Diode laser-based single-photon fluorometer. (From Ref. 12.)...

A single photon fluorometer consists of the following subsystems an optical spectrometer (including a pulsed light source), a data acquisition system (consisting of timing electronics) and a data analyser (composed of a computer with re-convolution software). Birch and Imhof [16] have widely published on instrumentation design and analytical methods. 

Fig. 6.7. Schematic diagram of a single-photon timing fluorometer.

The time resolution of a phase fluorometer using the harmonic content of a pulsed laser and a microchannel plate photomultiplier is comparable to that of a single-photon counting instrument using the same kind of laser and detector. 

Dyads (1 - 4) were synthesized by the method described previously. Fluorescence spectra were measured in degassed acetonitrile solutions at 2S °C with a Hitachi 8S0 spectrofluorometer. The excitation wavelength was the Soret maximum. Fluorescence lifetimes were measured at 25 °C using a Horiba NAES-500 ns-fluorometer interfaced to an NEC PC-9801 RX personal computer. The excitation light below 420 nm was cut off with a glass filter. The fluorescence was detected by a single-photon counting system and analyzed as the sum of two exponential components after deconvolution of the instrument response function. NMR spectra were recorded on a JEOL JNM GX-270 NMR spectrometer. 

There has been a considerable decline in the number of papers which deal with the details of techniques of measurement of fluorescence decay. This is no doubt due to the fact that the alternative methods are now essentially well established. Nevertheless a microcomputerized ultrahigh speed transient digitizer and luminescence lifeline instrument has been described . A very useful multiplexed array fluorometer allows simultaneous fluorescence decay at different emission wavelength using single photon timing array detection . Data collection rates could approach that for a repetitive laser pulse system and the technique could be usefully applied to HPLC or microscopy. The power of this equipment has been exemplified by studies on aminotetraphenylporphyrins at emission wavelengths up to 680 nm. The use and performance of the delta function convolution method for the estimation of fluorescence decay parameters has been... 

The time decay of fluorescence intensity measurements of a i-acid glycoprotein was performed with an Edinburgh Analytical Instruments CD 900 fluorometer. The technique used was time correlated single photon counting. The sample was excited with series of pulses at a frequency of 20 kHz. The time decay of ai-acid glycoprotein was measured by tlie phase method. 

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