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Triplet excitation energies

In principle, the excitation energy would be expected to be distributed between ketones (5)and (6) in a ratio dependent on the substituent R, and the distribution would be expected to favor the ketone having the lowest triplet excitation energy. [Pg.263]

In Section 3.1 it was shown that the photoreduction of benzophenone can be quenched by addition of small amounts of triplet quenchers such as oxygen or ferric dipivaloylmethide.<60) In fact this was presented as evidence that the benzophenone triplet was involved in the photoreduction. This reaction can also be quenched by naphthalene. In the presence of naphthalene, light is still absorbed by benzophenone and thus benzophenone triplets are produced. However, photoreduction products are decreased. On examining this reaction with flash photolysis, triplet-triplet absorptions were observed but these absorptions corresponded to those of the naphthalene triplet. Thus the triplet excitation energy originally present in the benzophenone triplet must have been transferred to naphthalene and since little of the photoreduction product was observed, this transfer must have been fast in relation... [Pg.58]

The CCS, CC2, CCSD, CC3 hierarchy has been designed specially for the calculation of frequency-dependent properties. In this hierarchy, a systematic improvement in the description of the dynamic electron correlation is obtained at each level. For example, comparing CCS, CC2, CCSD, CC3 with FCI singlet and triplet excitation energies showed that the errors decreased by about a factor 3 at each level in the coupled cluster hierarchy [18]. The CC3 error was as small as 0.016 eV and the accuracy of the CC3 excitation energies was comparable to the one of the CCSDT model [18]. [Pg.12]

Thus, the unknown values of i ed and AGf can be determined from the intercept and slope of the linear plots of (AG /e) versus (LGtJey as shown in Fig. 9. The °red values of various metal ion-carbonyl complexes thus obtained are summarized in Table 2 [113,114]. The °rea values of the triplet excited states are obtained by adding the triplet excitation energies and are listed in Table 2. [Pg.255]

J < D, E. The triplet excitation energy is localized (on the time scale of the ESR measurement) on one porphyrin ring. If this condition applies, changes in D and E values, and triplet kinetics must stem from a dimerization induced change in structure of dimer constituents. [Pg.147]

Photoisomerization of alkenes via the triplet excited state is known to be possible by triplet sensitization, usually efficient in conjugated C=C bonds that fulfill the requirement of possessing triplet excited energies below those of the typical triplet sensitizers such as acetone, acetophenone, benzophenone, etc. (Table 2). Sensitization with the opposite order of triplet excited energies is possible in cases with strong electronic or strong... [Pg.643]

SCHEME 1. The effect of the triplet excitation energy of the sensitizer on the Z/E isomerization of stilbene at the photostationary state. Reprinted with permission from Ref. 7. Copyright (1964) American Chemical Society... [Pg.644]

As a first order approximation, the SP-DFT approach connects the spin-potential directly with the singlet-triplet excitation energy. Thus, the gap defined by the highest beta occupied molecular orbital, HOMO, and the... [Pg.8]

Table 2 Spin-potential, e iMC) — eHOMO SaP an< singlet-triplet excitation energy, AE, for Ca, Sr and Ba The confinement radius, Rc, is reported in atomic units and the other quantities in eV... Table 2 Spin-potential, e iMC) — eHOMO SaP an< singlet-triplet excitation energy, AE, for Ca, Sr and Ba The confinement radius, Rc, is reported in atomic units and the other quantities in eV...
In Table 6 we report the range of vertical excitation energies AE for all final spin symmetries S, in the frozen minimum configurations Qmin(/i. 5), for all values of n and 5. The complete spectmm (available upon request from the authors) is very dense and not much informative. The listed energies give a quantitative prevision of the spectral range where a fast (optical) spectroscopy is likely to locate the intraband HOMO excitations of the C")0 ions. For the experimentally most accessible case n = 2, 5 = 1, here follows the complete list of the triplet-triplet excitation energies 127, 149, 150, 178, 182, 218, 326, 337, and 346 meV. [Pg.297]

Herkstroeter, W. G., A. A. Lamola, and G. S. Hammond Mechanisms of photochemical reactions in solution. XXVIII. Values of triplet excitation energies of selected sensitizers. J. Amer. chem. Soc. 86, 4537 (1964). [Pg.75]

Here, grs is a parameter that is quantified either from experimental data, or is calculated by an ab initio method as one-half of the singlet-triplet excitation energy gap of the r—s bond. In terms of the qualitative theory in Chapter 3, grs is therefore identical to the key quantity —2(3 5 - This empirical quantity incorporates the effect of the ionic components of the bond, albeit in an implicit way. (c) The Hamiltonian matrix element between two determinants differing by one spin permutation between orbitals r and s is equal to grs. Only close neighbor grs elements are taken into account all other off-diagonal matrix elements are set to zero. An example of a Hamiltonian matrix is illustrated in Scheme 8.1 for 1,3-butadiene. [Pg.224]

Lowest singlet and triplet excitation energies of buckminsterfullerene in ev... [Pg.559]

Table 20 Triplet excitation energies (eV) and phosphorescence lifetimes r (s) of azaben-zenes and azanaphthalenes calculated for different state symmetries and spin sublevel components by random phase approximation (HF) and MCQR with double zeta (DZ) basis set. Table 20 Triplet excitation energies (eV) and phosphorescence lifetimes r (s) of azaben-zenes and azanaphthalenes calculated for different state symmetries and spin sublevel components by random phase approximation (HF) and MCQR with double zeta (DZ) basis set.
Larsen H, Hald K, Olsen J, J0rgensen P (2001) Triplet excitation energies in full configuration interaction and coupled-cluster theory. J Chem Phys 115 3015-3020. [Pg.91]

Previtali and Scaiano have attempted to correlate rates of hydrogen abstraction with thermodynamic parameters 69> along the lines of Polanyi 70>. In this approach (AH proportional to AH) the exothermicity of hydrogen abstraction varies with the triplet excitation energy and the carbonyl 51-bond energy, at constant C—H and O—H bond energies. [Pg.18]


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See also in sourсe #XX -- [ Pg.58 ]

See also in sourсe #XX -- [ Pg.35 ]




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Excited triplet

Triplet energy

Triplet excitation

Triplet excition

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