Heavy atom effect naphthalene

Table 5.10. External Heavy-Atom Effect on Naphthalene 32b),a...

The effect of the substitution of a heavy-atom directly onto the nucleus of aromatic compounds (internal heavy-atom effect) on intercombinational radiative and nonradiative processes can be seen by examination of experimental data obtained for naphthalene and its derivatives. The data obtained by Ermolaev and Svitashev<104) and analyzed by Birks(24) to obtain individual rate constants for the various processes are collected in Table 5.9. 

Table 5.9. Internal Heavy-Atom Effect on Naphthalene<24 1 4> ...

Unless otherwise specified, both qy and x refer to the same process, indicated by f for fluorescence and p for phosphorescence. For naphthalene, qy is for fluorescence and T is for phosphorescence. bNote heavy atom effect in phosphorescence. 

The biphenyl, naphthalene, pyrene, and triphenylene adducts display intense room-temperature phosphorescence.237 238 These observations indicate the occurrence of a mercury heavy atom effect, which promotes... 

Table 4.4 The effect of the internal heavy atom effect on the fluorescence efficiency of naphthalene and its derivatives. Fluorescence quantum yields determined in solid solution at 77K...

Tab. 3.3. Heavy atom effect on emissive properties of naphthalene (from Wehry, 1990)...

Recently, the adducts formed between [Hg3(/x-C, C-C6F4)3] and polyaromatics including pyrene, naphthalene, and biphenyl, respectively, have been isolated. The crystalline samples of the adducts showed red, green, and blue phosphorescence, respectively, at 77 K and room temperature (Figure 7). Owing to the heavy atom effects, these adducts... 

The extinction coefficient of triplet benzophenone has been remeasured as 7220 320 dm moF cm at 530 nm and this has been used to measure the triplet yield for zinc tetraphenylporphine. The sensitization of naphthalene by benzophenone has been examined in different hydrocarbon or ethanol-ether glasses.Internal heavy-atom effects on the T, states of monochloro-... 

These selection rules can be related to spin-orbit coupling with the help of the Fermi golden ride. (Cf. Section 5.2.3.) The values k j 10 s for naphthalene and kgj 10 s " for I-bromonaphthalene (Birks, 1970), the difference of which can be explained through the heavy atom effect, also indicate clearly the influence of spin-orbit coupling. The fact that the rate... 

Heavy atom effects on the decay dynamics of triplet state ion pairs have been studied in chloranil-naphthalene 1 2 termolecular systems. The triplet exciplexes and radical pairs involved in geminate recombination which occurs with the methylene blue triplet and p-iodoaniline have been examined for spin-orbit coupling induced magnetic field effects . 

The triplet state photophysics of naphthalene and a,u-diphenylpolyenes photogenerated in trapped heavy cation exchanged zeolites have been characterized. 0 The application of the modified zeolite environment provides a powerful new method for induction and observation of external heavy atom effects. Triplet excitation energy transport kinetics in vapour deposited naphthalene has been followed by an analysis of the kinetics of phosphorescence and delayed fluorescence. The assorted decays... 

Ghosh. S. Petrin, M. Maki, A.H. Sousa, L.R. Dependence of the triplet state properties on the orientation of metal ion perturbers in naphthalene-crown ether metal ion complexes. I. External heavy atom effect. J. Chem. Phys. 1987. 87. 4315-4323. 

As mentioned before, the energy of the first triplet state Tj can be taken from the 0-0 vibronic of the Tj So transition (or from the Sq -> Tj transition when induced by the external heavy atom effect [23]), or from the band onset. This is illustrated in Fig. 15.7 for naphthalene, which also includes the transient triplet-triplet absorption of this compound. 

Quantum yields for fluorescence and phosphorescence from several 1-substituted naphthalenes as well as their observed phosphorescence lifetimes, T, are shown in Table II. The data for halogenated naphthalenes clearly demonstrate the heavy atom effect on intersystem crossing efficiency. Such data strongly suggest that substituent effects on photo-... 

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