Electronic excitation energies

These results do not agree with experimental results. At room temperature, while the translational motion of diatomic molecules may be treated classically, the rotation and vibration have quantum attributes. In addition, quantum mechanically one should also consider the electronic degrees of freedom. However, typical electronic excitation energies are very large compared to k T (they are of the order of a few electronvolts, and 1 eV corresponds to 10 000 K). Such internal degrees of freedom are considered frozen, and an electronic cloud in a diatomic molecule is assumed to be in its ground state f with degeneracy g. The two nuclei A and... 

Agranovioh V M and Galanin M D 1982 Electronic Excitation Energy Transfer in Condensed Maffer (Amsterdam Elsevier/North-Flolland)... 

There are a some known cases where MNDO gives qualitatively or quantitatively incorrect results. Computed electronic excitation energies are underestimated. Activation barriers tend to be too high. The correct conformer is not... 

Electronic excitation energies can be approximated by differences between filled and empty orbital energies. Again, however, a more accurate treatment requires a separate calculation for the ground and excited state (represented by two different Slater determinants). 

For C3H2 to be identified in space from its UV -VUV spectra, one needs to know reliable values of its low vertical electronic excitation energies. For that purpose, a number of experimental studies [30] have been realized in an attempt to observe C3H2 electronic transitions between 2000 and 6000 A. These experiments having failed, computational chemistry is the alternative left to search for stable electronic states, if any, which might have been overlooked in the region between 2 and 6 eV. 

Here (Oj is the excitation energy ErE0 and the sum runs over all excited states I of the system. From equation (5-37) we immediately see that the dynamic mean polarizability a(co) diverges for tOj=co, i. e has poles at the electronic excitation energies 0)j. The residues fj are the corresponding oscillator strengths. Translated into the Kohn-Sham scheme, the exact linear response can be expressed as the linear density response of a non-interacting... 

Electronic Excitation Energies and the Singlet/Triplet Splitting in Carbenes... 

We conclude this chapter with an overview of how modem density functional theory deals with electronic excitation energies. From the very beginning, electronically excited states... 

Table 9-14. Electronic excitation energies for single electron excitations from the K (b3u) orbital of C2H4 [eV] using an augmented POL basis set.

In concentrated dye solutions, when homotransfer of electronic excitation energy may take place due to inhomogeneous broadening, we observed [29, 40] the following interesting features ... 

Forster Th (1960) Transfer mechanisms of electronic excitation energy. Radiat Res Suppl 2 326-339... 

Gulis IM, Komiak AI, Tomin VI (1978) The electronic excitation energy transfer at conditions of dye spectra inhomogeneous broadening. Izv Akad Nauk SSSR, ser fiz 42 307-312... 

Photolysis with light of around 300 nm wavelength, provides electronic excitation energy of around 400 kJ mol" sufficient to bring about... 

Agranovich, V. M. and Galanin, M. D. (1982). Electronic Excitation Energy Transfer in Condensed Matter. North-Holland Publishing Company, Amsterdam. 

Numerous autoxidation reactions of aliphatic and araliphatic hydrocarbons, ketones, and esters have been found to be accompanied by chemiluminescence (for reviews see D, p. 19 14>) generally of low intensity and quantum yield. This weak chemiluminescence can be measured by means of modern equipment, especially when fluorescers are used to transform the electronic excitation energy of the triplet carbonyl compounds formed as primary reaction products. It is therefore possible to use it for analytical purposes 35>, e.g. to measure the efficiency of inhibitors as well as initiators in autoxidation of polymer hydrocarbons 14), and in mechanistic studies of radical chain reactions. 

Peroxy radical recombination appears to be the most important source of the electronic excitation energy emitted during hydrocarbon autoxidation. In addition to the above-mentioned energetic considerations, this is clear from the following experimental facts the termination rate for secondary peroxy radicals is 103 times faster than for tertiary peroxy radicals due to their having no a-hydrogen 14> the termination rate constant decreases by 1.9 with a-deuteration 39 40>. 

In the following scheme the difference between intra- and inter-molecular electronic excitation energy transfer is summarized (as formulated in 2>) ... 

Up to about 10 percent of crs-stilbene was obtained when trimethyl-dioxetane 129 was decomposed in the presence of trans-stilbene 182) the electronic excitation energy of the excited carbonyl compounds formed in the cleavage of 129 (see Section V.) was transferred to trans-stilbene, so effecting the photochemical trans-cis isomerization. When bis (2.4-dinitrophenyl) oxalate reacted with hydrogen peroxide (see Section V. C. in the presence of o-tolyl-propane-1.2-dione 130, 2-methyl-2-... 

Sukhan has used PTAB cationic micelles to enhance the CL reaction of 4-diethylaminophthalohydrazide with oxygen and Co(II) in the presence of fluorescein as sensitizer [48], This enhancement is mainly due to electron-excited energy transfer from the donor (4-diethylaminophthalohydrazide) to the acceptor (fluorescein). The addition of fluorescein combined with the presence of PTAB reduces the detection limit of Co(II) by a factor of 6. The method was successfully applied in the determination of Co in tap water samples. 

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