Davidov

V.A. Troitskij, E.A. Davidov - E.O. Eaton Electric Welding Inst., Ukraine. 

The study of the infrared spectrum of thiazole under various physical states (solid, liquid, vapor, in solution) by Sbrana et al. (202) and a similar study, extended to isotopically labeled molecules, by Davidovics et al. (203, 204), gave the symmetry properties of the main vibrations of the thiazole molecule. More recently, the calculation of the normal modes of vibration of the molecule defined a force field for it and confirmed quantitatively the preceeding assignments (205, 206). 

Out-of-Plane Vibrations, yCH and yCD. In accordance with all the proposed assignments (201-203), the bands at 797 and 716 cm correspond to yCH vibrators, which is confirmed by the C-type structure observed for these frequencies in the vapor-phase spectrum of thiazoie (Fig. 1-9). On the contrary, the assignments proposed for the third yCH mode are contradictory. According to Chouteau et al. (201), this vibration is located at 723 cm whereas Sbrana et al. (202) prefer the band at S49cm and Davidovics et al. (203) the peak at 877 cm This last assignment is the most compatible with the whole set of spectra for the thiazole derivatives (203) and is confirmed by the normal vibration mode calculations (205) (Table 1-25). The order of decreasing yCH frequencies, established by the study of isotopic and substituted thiazole derivatives, is (203) yC(4)H > 70(2)13 > yC(5)H. Both the 2- and 4-positions, which seem equivalent for the vCH modes, are quite different for the yCH out-of-plane vibrations, a fact related to the influence observed for the... 

The infrared and Raman studies of thiazole derivatives are numerous (111,173,197-226) though often only fragmentary. The only studies leading to a complete assignment of the observed bands are those of Chouteau and Davidovics et al. (201,203.204,227,228). 

The theory of the space-charge region in semiconductors was developed by Shottky [87, 88], Mott [89], Davidov [90, 91], Brattain [92] and several other authors. The idea concerning the effect of adsorption on characteristics of SCR of the semiconductor adsorbent was proposed by Hauffe [5, 6]. This theory was developed further by Volkenshtein and his group [4, 93, 94] as well as by Mark [95, 96], Morrison [21] and other scientists. Let us briefly dwell on general features of the model. 

S Noach, EZ Faraggi, G Cohen, Y Avny, R Neumann, D Davidov, and A Lewis, Microfabrication of an electroluminescent polymer light emitting diode pixel array, Appl. Phys. Lett., 69 3650-3652, 1996. 

Often the UV absorption tails into the visible due to light scattering by the microparticles, although the Amax is usually very close to that in solution. The aggregate CD spectrum, however, is markedly different from the solution-state spectrum, showing an intense bisigned Cotton effect coincident with the UV due the Davidov coupling. 

Weak coupling leads to minor alterations of the absorption spectrum (hypo-chromism or hyperchromism, Davidov splitting of certain vibronic bands). 

Amic D, Davidovic-Amic D, Trinajstic N (1995) J Chem Inf Comput Sci 35 136... 

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