Amplitude-average decay time

The definition used depends on the phenomenon under study. For instance, the intensity-averaged lifetime must be used for the calculation of an average colli-sional quenching constant, whereas in resonance energy transfer experiments, the amplitude-averaged decay time or lifetime must be used for the calculation of energy transfer efficiency (see Section 9.2.1). 

Determination of distances at a supramolecular level using RET 2S3 where the amplitude-averaged decay times are defined as ... 

Figure 21. The phase-averaged mean decay time as a function of frequency of the driving signal for different values of the amplitude, A = 1,0.3,0.1, kT = 0.1. Solid lines represent results of computer simulation, and dashed lines represent an adiabatic approximation (6.15).

Amplitudes, A, and time constants, Xj, obtained from a triexponential fit to the fluorescence decay of the acceptors in DMA and average lifetime, Tav. 

Setup and principle of FCS and FCCS have been reviewed extensively previously [12,13]. The technique is based on the statistical analysis of equilibrium fluorescence fluctuations induced by, e.g., the d3mamics of fluorescent molecules in a tiny observation volume. By correlating these fluctuations with itself at a later time r, an autocorrelation curve is obtained, which can be fitted to an appropriate model function to extract the characteristic time scales of the system. The two basic parameters of a FCS autocorrelation curve are the decay time, reflecting time scales of molecules dynamics, and the amplitude, indicating the average number of particles in the detection volume. 

From magnetic resonance spectroscopy [49] it is well-known that IB effects are adequately circumvented by the tricks of a spin echo experiment. For instance, in a two-pulse echo experiment, IB effects are averaged out and one probes spin dephasing determined by time-dependent fluctuations characteristic of HB only (and not IB). More specifically, a nll-r-n microwave pulse sequence is applied, where the first nil pulse creates a coherent superposition state for which a la = 1 and the n pulse, applied at time r after the first pulse, generates a spin coherence (the echo) at time 2r after the initial pulse. The echo amplitude is traced with r. The echo amplitude decay time is characteristic of the pure dephasing dynamics. For phosphorescent triplet states it is possible to make the echo optically detectable by means of a final nil probe pulse applied at time f after the second pulse [44]. In Fig. 3b, the optically detected echo amplitude decay for the zero-field transition at 2320 MHz of... 

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