Photon single, counting technique

Advanced Time-Correlated Single Photon Counting Techniques... 

Becker, W. (2005). Advanced time-correlated single photon counting techniques. Springer, Berlin Heidelberg New York. 

S. Yu. Egorov, V. F. Kamalov, N. I. Koroteev, A. A. Krasnovsky Jr, B. N.Toleutaev,andS. V. Zinukov, Rise and decay kinetics of photosensitized singlet oxygen luminescence in water measurements with nanosecond time-correlated single photon counting technique, Chem. Phys. Lett. 421 —424 (1989). 

Nemzek and Ware [7] have studied the fluorescence decay of 1,2-benzanthracene (and naphthalene) in 1,2-propanediol or purified mineral oil by the single photon counting technique over the temperature range 10—45°C. The fluorescence lifetimes, t0, were measured. In further experiments, which included a heavy atom fluorescence quencher, carbon tetrabromide in concentration [Q] 0.05—0.29 mol dm-3, no longer could the decay be characterised by an exponential with a constant lifetime. However, the decay of fluorescence was well described by an expression of the form... 

The time-resolved measurements were made using standard time-correlated single photon counting techniques [9]. The instrument response function had a typical full width at half-maximum of 50 ps. Time-resolved spectra were reconstructed by standard methods and corrected to susceptibilities on a frequency scale. Stokes shifts were calculated as first moments of cubic-spline interpolations of these spectra. 

Evidently we may look forward to more penetrating insights still into all these effects as the laser and single-photon counting techniques become further refined. It will obviously be very convenient if it always proves possible to justify the use of (35) and (36), and (15) and (16), with reasonable choices of p0, p Q, x0, and y0. 

Halpern and Ware (97) have measured the fluorescence lifetimes (if) of HFA using the time-correlated single photon counting technique over a wide pressure range (0.1-700 torr) from... 

Single-photon counting techniques again are of great vrdue in such measurements where intensites are in general low. 

Figure 16. Decay-associated spectrum resulting from a global analysis of the decay of the porphyrin fluorescence of pentad 22 following excitation of a — lxlO M chloroform solution with a 590-nm laser pulse. Data were obtained using the single photon counting technique, and the instrument response time was 0.035 ns. Decays at 14 different wavelengths were analyzed simultaneously, and the goodness of fit parameter was 1.12.

Becker W (2005) Advanced Time-Correlated Single Photon Counting Techniques. Springer Series in Chemical Physics Vol. 81... 

The polarized emission spectra and the apparatus response (recorded at emission wavelength) were sampled with a 0.12 ns channel width by the single-photon counting technique. Thanks to the stability of the pulses, the short-time limit of the experimental window is about 0.1 ns. The upper limit, imposed by the repetition rate of the pulses and the lifetime of the dye, is 2 ns. 

There are numerous spectroscopic studies of the chromophores bound to the chemically modified silica gel(2-4) but dynamic studies such as fluorescence lifetime measurements are rather limited. In their recent work, Lochmuller and Hunnicutt (5) have employed the time-correlated single photon counting technique and analyzed the non-exponential decays in detail to disclose the complex features of the interfaces through (10-(3-pyrenyl)decyl)dimethylmonochlorosilane chemically bonded to silica as a probe. Unfortunately, however, their method, though sophisticated enough to monitor heterogeneous fluorescence decays, cannot distinguish one microparticle from the other and hence unavoidably follows overall decays. 

Fluorescence decay curves for the pyrenyl emissions were obtained by a time - correlated single photon counting technique. The monoexponentlallty of these curves in both solvent phases is consistent with k4 k3 (l.e., that adiabatic exciplex formation is unlmportant(31)) and allows the decay constants to be equated to the excited state lifetimes. The rate constant for exciplex formation, k3, could be obtained uniquely from Eqn. 23 by assuming that kj+k2 is the Inverse of the fluorescence lifetime of 1 -ethylpyrene (EZ) i 1L- From Arrhenius and Eyring... 

The method s sensitivity can be estimated by following up the previous example. Assuming a fluorescence quantum yield of 0.1 and a spatial collection efficiency of 10 , a population of 5x10 excited molecules leads to 5 X 10 photons reaching the detector per pulse. Single-photon counting techniques easily allow the observation of 0.1-1 photon per pulse. Evidently fluorescence methods can easily be used to probe submil-litorr samples. 

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