Intramolecular band

The fact that using excitation in the CT absorption a number of Raman bands appears in the intermolecular mode region,while the intramolecular bands practically disappear, can be understood on the basis of the dimeric model. The modulation of the transfer integral t by the intermolecular vibrations, particularly the antiphase translational modes, provides an efficient mechanism for intensity enhancement at resonance with the CT transition. No such mechanism is operative for the intramolecular vibrational modes. 

The first successful experiment was carried out in 1983 by Seki et al. at HASYLAB, DESY, and published in 1984 [64], where the authors used hexatriacon-tane (n-CH3(CH2)32CH3) vacuum deposited on metal surfaces that are not dean to obtain standing molecular orientations. As the alkyl chains orient with their long axes perpendicular to the surface, the intramolecular band dispersion can be... 

Figure C3.1.7. Time-resolved optical absorjDtion data for the Soret band of photo lysed haemoglobin-CO showing six first-order (or pseudo-first-order) relaxation phases, I-VI, on a logaritlimic time scale extending from nanoseconds to seconds. Relaxations correspond to geminate and diffusive CO rebinding and to intramolecular relaxations of tertiary and quaternary protein stmcture. (From Goldbeck R A, Paquette S J, Bjorling S C and Kliger D S 1996 Biochemistry 35 8628-39.)...

Intramolecular H bond Polyvalent alcohols Chelation 3600-3500 (s) 3200-2500 Sharper than dimeric band above Broad and occasionally weak the lower the frequency, the stronger the intramolecular bond... 

Fradet227,232, in an esterification study on models, examined the reaction of octadecanoic acid with tetrabutoxytitanium. He found that a small amount of butyl octadecanoate is formed (absorption of the ester carbonyl at 1740 an-1) and that the carboxy absorption at 1710 cm-1 disappears completely. Simultaneously, two bands appear at 1560 and 1450 an-1, which is in agreement with Yoshino302. The ratio of the intensity of each of these two peaks to the intensity of ester peak (1740 cm-1) does not change when the concentration of the solution used in the spectroscopic study is varied consequently, the interaction between carbonyl and titanium is most probably intramolecular ... 

Although in the frequency region of the conventionally measured infrared and Raman spectra (400-4000 cm ) only intramolecular modes appear, some particular bands can be sensitive to intermolecular interactions typical of the different modes of packing of chains with identical conformations. 

Copolymers composed of electron-donating and electron-withdrawing units are considered to have intramolecular charge transfer structure.41 These copolymers show absorption bands at wavelengths longer than those of the corresponding homopolymers (Fig. 9.2). 

The first Raman and infrared studies on orthorhombic sulfur date back to the 1930s. The older literature has been reviewed before [78, 92-94]. Only after the normal coordinate treatment of the Sg molecule by Scott et al. [78] was it possible to improve the earlier assignments, especially of the lattice vibrations and crystal components of the intramolecular vibrations. In addition, two technical achievements stimulated the efforts in vibrational spectroscopy since late 1960s the invention of the laser as an intense monochromatic light source for Raman spectroscopy and the development of Fourier transform interferometry in infrared spectroscopy. Both techniques allowed to record vibrational spectra of higher resolution and to detect bands of lower intensity. 

From an energetic point of view, the bands at higher wavenumbers can be assigned to the Ss rings. However, the intensities were found as ca. 0.65 1 (pure infected) instead of 2.8 1 which would be expected from the natural abundance of the isotopomers. These discrepancies were solved by applying the mathematical formalism utilized in the treatment of intramolecular Fermi resonance (see, e.g., [132]). Accordingly, in the natural crystal we have to deal with vibrational coupling between isotopomers in the primitive cell of the crystal [109]. 

A similar mechanism was postulated for the Ca " -dependent inactivation of Ca -ATPase by ATP-imidazolidate [380] that results in intramolecular crosslinking with the formation of a new protein band of 125 kDa. In both cases the reactive carboxyl group was suggested to be the phosphate acceptor Asp351. 

The absorption bands of the binuclear complexes are red-shifted compared to the mononuclear analogs, and this is attributed to intramolecular n-n interactions between C N C ligands in solution (Figure 5.21a). 

Molecular Metal Complexes Compounds of this type do not form delocalized electronic bands in the sohd state, and their color is due to intramolecular electronic transitions. Many complexes of transition metals with organic ligands belong to this class. complexes with phenanthroline (red/colorless) and Ru + + with 2,2 -... 

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