Fluorescent decay profile

Fig. 21.8 Room-temperature fluorescent decay profile for Ba3BP30- 2.

Figure 21.23 exhibits the room-temperature fluorescence decay profiles of Ba3BP30i2 Eu powders. The experimental decay curve can be fitted by an equation with two exponential terms corresponding to two decay times of 20 ns (98.97%) and 522 ns (1.03%), respectively. 

Fig. 4.8. Fluorescence lifetime of a stained section of Convallaria resolved with respect to lifetime, excitation and emission wavelength (A) intensity image integrated over the time-resolved excitation-emission matrix (EEM) (B, D) time-integrated EEM from areas A and B respectively in (A) (C) fluorescence decay profile for /ex 490 nm and Aem 700 nm corresponding to area A (E) fluorescence decay profile for Aex 460 nm and /em 570 nm corresponding to area B.

Measurements of the hydrocarbon fluorescence lifetimes provide important information which is useful in interpreting the Stern-Volmer plots. In cases where Equation 1 is valid, the hydrocarbon fluorescence decay profiles must be the same with and without DNA. In some cases, BP for example, this is not the case. For BP the observed decay profile changes significantly when DNA is added (72). 

Figure 6. Fluorescence decay profiles of trans-7,8-dihydroxy-7,8-dihydro-BP and 8,9,10,11-tetrahydro-BA measured at 23 °C with and without native DNA. Taken from refs. 14 and 15. The upper left-hand corner contains an instrument response profile. Emission and excitation wavelengths, lifetimes, and values of x2 obtained from deconvolution of the lifetime data are also given.

Figure 4. Observed fluorescence decay profiles (points) and theoretical fits (solid lines), calculated by the deconvolution program according to Equation 2, using v as an adjustable parcuneter in the fit, for (A) H2TPP and (B) MgTPP in BuCl containing CBr at 77 K, following excitation at 515 nm and 424 nm, respectively. The concentration of CBr was (a) 0, (b) 0.4, emd (c) 0.8 mol/L. The parauaeters used in the fits were, for H2TPP, To=14.5 ns, L/2=0.83 A and v=l,4 x 10 s"-, and for MgTPP, To=15.5 ns, L/2=0.83 A and...

See also Iron hemoproteins excited-state relaxation, 170,175f Fluorescence decay profiles,... 

Fig. 21 Fluorescence decay profile of excimer (480 nm) for no DTAB, curve A (premaximum), and 0.001 M DTAB, curve B (postmaximum), corresponding to pH 6.4 in Fig. 19...

An interesting porphyrin-bis-quinone Q-L-P-L-Q molecule with two quinone fragments one of which was located above the porphyrin plane and the other below this plane, was synthesized in Refs. [146, 147]. As determined by X-ray technique, the two quinones are coplanar with the porphyrin and are symmetrically displaced at a distance 3.4 A from it. This molecule shows a fluorescence decay profile in a liquid solution that is best fited by a distribution of lifetimes rather than a single lifetime, as expected if the quinones are capable of changing their position relative to the porphyrin. 

Some interesting examples of the effects of rotational and vibrational relaxation on the fluorescence decay profile of levels near and above a predissociation are provided by the studies by Clyne and McDermid [37—40], and Clyne and Heaven [41, 42] on the B—X systems of the hetero- and homo-nuclear diatomic inter halogens. 

For an experimental demonstration of the capabilities of this system, Taylor et al. [69] studied the dual fluorescence decay of frans-stilbene as a function of temperature between —10 and 30° C. The fluorescence comprised two components, a short one varying between 125 and 64 ps and a longer one varying from 690 to 1450 ps over the range of temperatures studied. Typical fluorescence decay curves are shown in Fig. 21. The fluorescence decay curves were recorded over a total integration time of 2 s which represented a summation of 3 x 108 fluorescence decay profiles. The fluorescence profile of a single-shot would not be observable above the noise level. 

The laboratory coordinate system chosen for TIR fluorescence anisotropy measurements is illustrated in Figure 12.2. SRIOI molecules located at a water/oil interface (in the x-y plane) are excited by an s-polarized laser beam along the x -axis. The TIR fluorescence is then detected along the z-axis and its polarization is selected by a polarizer. The fluorescence decay profile observed under such a configuration is analysed for two limiting cases, depending on the structure of a water/oil interface two-dimensional or three-dimensional. 

A Magic-Angle Dependence of the TIR Fluorescence Decay Profile of SRIOI at a Water/Oil Interface... 

In the case of a water/DCE interface [(c) and (d)], on the other hand, a fitting of the data by a single-exponential function cannot be attained by setting an emission polarizer at 45°, as confirmed by deviations of Re and Cr from the optimum values (c). When the fluorescence decay profile is measured by setting an emission polarizer at 54.7° (d), fluorescence anisotropy can be reasonably fitted by a single-exponential function including the time response in the initial stage of excitation (see also and... 

In this section, we discuss methods that detect the time delay td between excitation of a fluorophore and arrival of a fluorescence photon. The distribution of times constitutes the fluorescence decay profile of the fluorophore. The average time lag between the excitation event and the emission is the fluorescence lifetime y of the fluorophore. The fluorescence decay contains information about dynamic processes that deplete the excited state (Fig. 2a). In time-resolved fluorescence experiments, the fluorescence decay is measured to gain information about these processes. 

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