On electronic spectra

A more complete coverage of the literature on electronic spectra of radicals is presented in our paper submitted for publication in Fortschr. Chem. Forsch. (Topics in Current Chemistry), where theafi initio studies are also reviewed and the existing open-shell computational procedures discussed. Recently we performed semiempirical all-valence-electron calculations on ground-state properties and electronic spectra of small radicals (Zahradnik, R., and P. Carsky, Theoret, Chim. Acta, 27, 121 (1972) and Carsky, P., M. Machacek, and R. Zahradnik, Coll. Czech. Chem. Commun., in press) and on equilibrium constants of dimerization reactions of small radicals (Zahradnik, R., Z. Slanina, and P. (5arsky, to be published). 

Iordanov TD, Davis JL, Masunov AE, Levenson A, Przhonska OV, Kachkovski AD (2009) Symmetry breaking in cationic polymethine dyes, part 1 ground state potential energy surfaces and solvent effects on electronic spectra of streptocyanines. Int J Quantum Chem 109 3592-3601... 

Muino PL, Callis PR (1994) Hybrid simulations of solvation effects on electronic-spectra -indoles in water. J Chem Phys 100(6) 4093 1109... 

M. F. Nicol, Solvent effects on electronic spectra, Appl. Spect. Rev. 8 183 (1974). 

Mulliken also studied other band spectra of diatomic molecules. Only one such study will be mentioned here and that is his study of copper iodide (Mulliken 1925c), where he examined the copper isotope effect. Mulliken s pioneering work was followed by more papers on isotope effects on electronic spectra (visible and UV) which will not be detailed here. Many of these papers deal with diatomics since the theory of such spectra is much better understood than that for general polyatomic systems. Further discussion of isotope effects on spectra will be mainly restricted to their use in the discovery of less abundant isotopes. 

Electronic and vibrational spectroscopy continues to be important in the characterization of iron complexes of all descriptions. Charge-transfer spectra, particularly of solvatochromic ternary diimine-cyanide complexes, can be useful indicators of solvation, while IR and Raman spectra of certain mixed valence complexes have contributed to the investigation of intramolecular electron transfer. Assignments of metal-ligand vibrations in the far IR for the complexes [Fe(8)3] " " were established by means of Fe/ Fe isotopic substitution. " A review of pressure effects on electronic spectra of coordination complexes includes much information about apparatus and methods and about theoretical aspects, though rather little about specific iron complexes. ... 

For a discussion of the effect of hydrogen bonding on electronic spectra, see Lees Burawoy Tetrahedron 1963, 19, 419. 

CsNiCl3-type). Table 6 summarizes results on electronic spectra. The three spin-allowed transitions are usually observed and extensive vibrational contribution has been observed in single crystal spectra.120,121 Intense spin-forbidden transitions may also be observed122 due to exchange interactions in the solid phase. The diiodide123,124 and the complex halides121 show trigonal distortion. 

The major changes in the new edition are as follows There are three new chapters. Chapter 1 is a review and summary of aspects of quantum mechanics and electronic structure relevant to molecular spectroscopy. This chapter replaces the chapter on electronic structure of polyatomic molecules that was repeated from Volume I of Quantum Chemistry. Chapter 2 is a substantially expanded presentation of matrices. Previously, matrices were covered in the last chapter. The placement of matrices early in the book allows their use throughout the book in particular, the very tedious and involved treatment of normal vibrations has been replaced by a simpler and clearer treatment using matrices. Chapter 7 covers molecular electronic spectroscopy, and contains two new sections, one on electronic spectra of polyatomic molecules, and one on photoelectron spectroscopy, together with the section on electronic spectra of diatomic molecules from the previous edition. In addition to the new material on matrices, electronic spectra of polyatomic molecules, and photoelectron... 

Investigations of the electronic structure of quadruply bound dimers have relied heavily on electronic spectra to reveal the nature of the excited-state configurations. The availability of quantitative molecular orbital calculations coupled with single-crystal polarized electronic absorption spectral studies of quadruply bound dimers at low temperature has firmly established certain features of the excited electronic states of these compounds. A discussion of electronic spectra follows and a tabulation of energies associated with 6 - 6 transitions in quadruply bound dimers is given in Table 111. 

The substitution of hydrogen by its heavy isotope alters the vibration frequencies without affecting the force constants. It follows that comparison of the Raman spectra (and also infrared spectra) of deuterated and ordinary molecules can be used to determine the various structural parameters which are necessary for the calculation of force constants and facilitate many theoretical calculations concerned with vibrational spectra. The aim of measurements on electronic spectra of... 

L. Serrano-Andres, M. P. Fulscher and G. Karlstrom, Solvent effects on electronic spectra studied by multiconfigurational perturbation theory, Int. J. Quantum Chem., 65 (1997) 167-181. 

Py) < (CN , OH ) < (CN, CN ). A molecular orbital treatment advanced for the elucidation of axial ligation effects on electronic spectra of the corrin complexes (19) may be applied in this case. 

A consistent model permitting rationalization and prediction of the solvato-chromic behaviour of coordination compounds with MLCT absorption has been described [428]. According to this qualitative model, the changing relationship between the metal-ligand bond dipolarities in the ground and MLCT excited state determines whether the complex is negatively, positively, or not solvatochromic [428]. For comprehensive reviews on solvent effects on electronic spectra of metal complexes, see references [15, 17]. 

Another type of applications, in which diffuse function must be used, are calculations on electronic spectra. With Rydberg states, the importance of diffuse functions is obvious. By their electronic structure the Rydberg states resemble the corresponding molecular cation... 

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