Excitation, electronic excited states involved

The ground configuration of Ar is KL3s 3p, giving an inverted P /2 multiplet. The excited states involved in laser action involve promotion of an electron from the 3p orbital into excited As,5s,Ap,5p,3d,Ad,... orbitals. Similarly, excited states of Kr involved arise from promotion of an electron from the Ap orbital. In Ar the KL3s 3p configuration gives rise to 5, V, terms (see Section 7.1.2.3). Most laser transitions involve the core in one of the states and the promoted electron in the Ap orbital. 

Superexchange describes interaction between localized moments of ions in insulators that are too far apart to interact by direct exchange. It operates through the intermediary of a nonmagnetic ion. Superexchange arises from the fact that localized-electron states as described by the formal valences are stabilized by an admixture of excited states involving electron transfer between the cation and the anion. A typical example is the 180° cation-anion-cation interaction in oxides of rocksalt structure, where antiparallel orientation of spins on neighbouring cations is favoured by covalent... 

Steady-state irradiation of Eosin and PDO leads to the formation of ethyl benzoate, benzil, and benzoyloxycarboxylate. Energy transfer from Eosin to PDO is unfavorable and the decomposition of PDO is most likely sensitized by electron transfer. In addition, at the concentration of PDO employed the fluorescence of Eosin is not significantly quenched and it is concluded that the excited state involved is the triplet of Eosin. 

Modified Notation.—The Platt notation is applied mainly to aromatic molecules and based on the conceptually simple perimeter model description of electronic excitations (7). Ground states are labeled A, the excited states involved in certain very high intensity transitions are labeled B and the excited states produced in partially forbidden transitions (i.e., those in which selection rules are violated) are labeled L and C. The notation is derived from selection rules appropriate for imaginary monocyclic aromatic systems. States to which transitions are forbidden because of a large change in angular momentum are L states. Transitions to C states are parity forbidden that is, they violate the g g, u u selection rule. In common aromatics other than benzene these selection rules break down and transitions to L and C states occur but at lower intensities relative to B states. 

Some simple organometallics have been studied. Poly(silanes) and germanes exhibit very interesting behavior, since they are photochromic and appear to possess excitonic, charge delocalized excited states involving the sigma electrons of the organometallic backbone. 112) THG measured susceptibilities of up to 1 x... 

It was shown that the solvent effect is generally significant and that it therefore needs to be taken into account properly. For nonpolar structures such as the bare tt backbone of TSB such an effect has been found to follow closely the refraction index of the medium though deviations may occur as a result of the nature of the excited states involved. Such deviations are more prominent when polar groups are attached to the tt backbone and become quite large for the dipolar structure of NATSB. It was shown by Frediani et al. [117] that to enhance the solvent effect it is more important to have a solvent with a high refractive index and that the static polarity of the solvent plays a minor role for the nondipolar structures which are known as the most promising ones. Another source of solvent dependence can also be found in how the electronic structure of the... 

Several recent studies examined photoinduced ET in dyads featuring transition metal chromophores that are dissimilar to the d6 transition metal polypyridine complexes used in the type 1 and type 2 dyads that have been discussed in the preceding sections. Since the molecular and electronic structure of the excited states involved in these systems is unique from the type 1 and type 2 dyads, results on these systems are discussed separately. 

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