Charge singlet excited state

The decomposition of dioxetanone may involve the chemically initiated electron-exchange luminescence (CIEEL) mechanism (McCapra, 1977 Koo et al., 1978). In the CIEEL mechanism, the singlet excited state amide anion is formed upon charge annihilation of the two radical species that are produced by the decomposition of dioxetanone. According to McCapra (1997), however, the mechanism has various shortfalls if it is applied to bioluminescence reactions. It should also be pointed out that the amide anion of coelenteramide can take various resonance structures involving the N-C-N-C-O linkage, even if it is not specifically mentioned. 

The observation of selective fluorescence quenching by G C base pairs is consistent with the energetics of electron transfer (charge separation) from the bases to the singlet excited state Sa, which can be estimated using Weller s equation [26] ... 

Dias FB, King S, Monkman AP, Perepichka n, Kryuchkov MA, Perepichka IF, Bryce MR (2008) Dipolar stabilization of emissive singlet charge transfer excited states in polyfluorene copolymers. J Phys Chem B 112 6557-66... 

The lowest excited states of paramagnetic metal complexes are described by configuration interactions of the porphyrin (7T,tt ) excited singlet and triplet states and the "porphyrin-to-metal" or metal-to-porphyrin charge-transfer excited states (35,36). Thus T (phosphorescence) emission of paramagnetic metal complexes decays... 

A similar supramolecular approach, in which both n-n stacking stacking of pyrene on the SWNT surface and alkyl ammonium-crown ether interactions were used in the self-assembly process of a fullerene derivative with SWNTs, was recently reported (Scheme 9.22).72 The nanohybrid integrity was probed with various spectroscopic techniques, , and electrochemical measurements. Nanosecond transient absorption studies confirmed electron transfer as the quenching mechanism of the singlet excited state of C60 in the nanohybrid resulting in the formation of SWNT"1"/ Pyr-NH3 + /crown- charge-separated state. 

The exact point at which the nerve impulse is transmitted is not established with certainty, but it has to occur before the hydrolysis step because hydrolysis is too slow to account for the nerve impulse. One theory suggests that an electrical signal is generated at the instant of light absorption by electron transfer to a w------> rr singlet excited state that has substantially charged carbon atoms. 

Bunker et al. also reported approximately three aminofullerene derivatives (3, 32, 33, Fig. 25) that show intramolecular electron transfer from the amino group to the singlet excited state of the fullerene core [189], Although the intramolecular electron transfer shares some characteristics with the classical twisted intramolecular charge transfer in molecules represented by p-N,N-dimethylaminobenzonitrile the amino-C6o derivatives are in fact better classified as redoxdyads [189],... 

Perturbation of the lanthanide singlet excited state, in which quenching by electron- or charge-transfer processes may be altered by the binding of analytes to the metal centre. For example the W-alkylphenanthridinium unit in 11.32 binds selectively to the electron-rich guanine-cytosine... 

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