Absorption and Emission Properties

3 Photophysics and Spectroscopy of AvGFP 3.1 Absorption and Emission Properties 

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At this stage, we can draw several important conclusions regarding the absorption and emission properties of cofacial dimers formed by two identical PPV chains ... 

Replacing the nitrile group by a benzothiazole produces an important subclass of fluorescent compounds represented by thioflavin T (25, Fig. 10). It is not clear if this compound undergoes deactivation via intramolecular rotation that would meet the criterion for a molecular rotor. The steady-state absorption and emission properties of thioflavin T has been attributed to micelle formation [53, 54], dimer and excimer formation [55, 56], and deactivation through intramolecular rotation [57]. 

Scheme 5 shows a group of alkynylgold(i) complexes for which the studies focused on the UV-VIS electronic absorption and emission properties. Most of these compounds are of the type [(L)AuC=CR], for which the methods of synthesis have been summarized above. The products were found to show phosphorescence in various polymorphs and crystal forms of solvates. Although there are no metallophilic interactions discernible in the crystal between most of the monomers due to the steric effect of the large tertiary phosphines, there is nevertheless strong excitonic coupling based on other weak interactions, which depend on the organization of the molecules in the crystal.105,106... 

To complete the description and get the connection with the solute emission and absorption spectra, there is need of the correlation functions of the dipole operator pj= (a(t)+af(t))j and, consequently, the differential equation for the one solute mode has to be solved. The reader is referred to [133] for detailed analysis of this point as well as the equations controlling the relaxation to equilibrium population. The energy absorption and emission properties of the above model are determined by the two-time correlation functions ... 

H.-Z. Tang, M. Fujiki, and M. Motonaga, Alkyl side chain effects of optically active polyfluorenes on their chiroptical absorption and emission properties, Polymer, 43 6213-6220, 2002. 

In some cases, photobleaching the acceptor can yield a photoproduct with distinct absorption and emission properties, which can contribute to the post-bleach donor signal, resulting in the overestimation of FRET efficiency (10). The correction factor e for such acceptor-photoproduct is calculated as... 

In summary, an adiabatic model for the first excited state of BA is able to account well for the equilibrium absorption and emission properties of BA. It seems reasonable to assume that many of the dual fluorescent molecules would be well described by an adiabatic model of this type. In the following section we show the dynamic properties of BA are also well described by an adiabatic model. Indeed, the results are revealing from the standpoint of understanding small barrier charge transfer reactions in general. 

The ESIPT of 2-(2 -hydroxyphenyl)-4-methyloxazole (HPMO) (27) has been explored by Douhal and co-workers [166] for its probe characteristics in a variety of organized media which include cyclodextrin, calixarene, micelle, and HSA. The incorporation of HPMO into hydrophobic cavities in an aqueous medium involves the rupture of its intermolecular hydrogen bond to water and formation of an intramolecular hydrogen bond in the sequestered molecule. Upon excitation (280-330 nm) of this entity, a fast intramolecular proton-transfer reaction of the excited state produces a phototautomer (28), the fluorescence of which (Xm = 450 170 nm) shows a largely Stokes-shifted band. Because of the existence of a twisting motion around the C2—C bond of this phototautomer, the absorption and emission properties of the probe depend on the size of the host cav-... 

Absorption and emission properties were similar to those of unattached [Re(phen)(CO)3 (py)]+ with high quantum efficiencies and long emission lifetimes. Quenching of the emission occurred in the presence of O2 suggesting their use for dioxygen sensors. 

Solvatochromism is the dependence of the absorption and emission properties (i.e. signal maximum, intensity, lifetime) of a compound on the sol-... 

Investigations into the absorption and emission properties are especially important since they can reveal if the photophysical properties of the molecular components are different when immobilized, compared to when they are dissolved in solution. These investigations typically involve both steady-state and time-resolved methods. Time-resolved or transient techniques yield information about the lifetime of the emitting state, while flash photolysis yields the absorption characteristics of the photochemically produced transient species. Information of this kind is essential for understanding the interactions between the molecular... 

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