Triplet State Studies

T. Shiga and L. H. Piette, Triplet state studies of flavins by electron paramagnetic resonance—II, Photochem. Photobiol. 3, 223-230 (1964). 

Hirota N, Yamauchi S. Short-lived excited triplet states studied by time-resolved EPR spectroscopy. J Photochem Photobiol C Photochem Rev 2003 4 109-24. 

Although triplet state studies in rigid glasses are more convenient, it must be pointed out that they have yielded far less quantitative and precise data than have the single-crystal investigations (39,45). Initially the disadvantage of single-crystal studies is that suitable host crystals are difficult to find. 

More interestingly, triplet state studies have produced date which expand our experience of intramolecular triplet state interactions and are relevant to the issue regarding the existence of triplet excimer species in naphthalene compounds(25-30). The data may be summarized as follows ... 

One of the predominant sources of fluctuations in addition to diffusion in PCS is from intersystem crossing to the lowest excited triplet state of the fluorophore [38]. Correlations due to triplet crossing tend to be dominant at very short lag times in comparison with the part of the autocorrelation curve dominated by diffusion (see figures 2.9 and 2.12). Numerous triplet state studies have been conducted principally using the organic dyes rhodamine 6G (R6G) and fluorescein [42,54]. A model for the autocorrelation function of a signal whose fluctuations derive from a combination of diffusion and triplet crossing has been developed [54],... 

Table 2 Triplet State Studies in Low Temperature Glasses...

Table 3 Triplet State Studies on Polymer Films...

Table 4 Triplet State Studies in Solutions of Homopolymers...

Varela AP, Burrows HD, Douglas P, Miguel MG (2001) Triplet state studies of P-carbolines. J Photochem Photobiol A Chem 146 29-36... 

Many early studies in ESR spectroscopy were concerned with anions, cations and triplet states derived from conjugated molecules. The unpaired electron(s)... 

Quenching of the Intersystem Crossing to the Triplet State 521 Photoinduced 1RAV Studies 522 Time-Resolved Photoinduced Studies 524 Sensitization of Photoconductivity 525 Magnetic Properties 526... 

Irradiation of 5-acetyldibenz[i>,/]azepine (19) in the presence of. V-methylmaleimide results in a mixture of the homo dimer 20 and the mixed dimer 21. No [2 + 2] cycloadducts are obtained, however, with other alkenes such as styrene, acetylenedicarboxylic acid, dimethyl fumarate or acrylonitrile.32 Later studies have demonstrated that the dimerization occurs via the excited triplet state.196... 

Ward (Ref 15) and Brown and Williams (Ref 16) studied nitrobenzene with radiation > 3300A using tetrahydrofuran (THF) as solvent in degassed solns. The effects of low temp were also studied. An ESR signal, attributed to the C6HsN(02)H radical, was obtained with THF as solvent. No ESR signal was obtained when perfluoronaphthalene was added. They concluded that the triplet state of nitrobenzene was an intermediate... 

The moments of complexes containing NO offer a puzzling problem. The diamagnetism of compounds of iron and ruthenium suggests that Feiv and RuIV form a double bond with NO, making seven bonds in all, which woud lead to /t = 0. But this structure cannot be applied to [Co(NH3)6-NO]Cl2, which has a moment corresponding to a triplet state. Further study of such complexes is needed. 

Lu, C. Y. Lui, Y.Y. (2002). Electron transfer oxidation of tryptophan and tyrosine by triplet states and oxidized radicals of flavin sensitizers a laser flash photolysis study. Biochimica et Biophysica Acta (BBA) - General Subjects, Vol. 1571, No.l, (May 2002), pp. 71-76, ISSN 0304-4165... 

Rao reported measurement of third-order optical non-linearity in the nanosecond and picosecond domains for phosphorus tetratolyl porphyrins bearing two hydroxyl groups in apical position [89]. Strong nonlinear absorption was found at both 532 nm and 600 nm. The high value of nonlinearity for nanosecond pulses is attributed to higher exited singlet and triplet states. Time resolved studies indicate an ultra-fast temporal evolution of the nonlinearity in this compound. 

Fujii, R. et al., Cis-to-trans isomerization of spheroidene in the triplet state as detected by time-resolved absorption spectroscopy, J. Phys. Chem. A, 106, 2410, 2002. Montenegro, M.A. et al., Model studies on the photosensitized isomerization of bixin, J. Agric. Food Chem., 52, 367, 2004. 

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