Intermolecular coupling effects

G2, to G3, and to G4, the effective enhancement was 10%, 36%, and 35% larger than the value estimated by the simple addition of monomeric values. The enhancement included the local field effect due to the screening electric field generated by neighboring molecules. Assuming the chromophore-solvent effect on the second-order susceptibility is independent of the number of chro-mophore units in the dendrimers, p enhancement can be attributed to the inter-molecular dipole-dipole interaction of the chromophore units. Hence, such an intermolecular coupling for the p enhancement should be more effective with the dendrimers composed of the NLO chromophore, whose dipole moment and the charge transfer are unidirectional parallel to the molecular axis. 

In condensed phases, the noncoincidence effect between IR and Raman spectra provides insights into the intermolecular coupling [170, 171]. The combination of IR and Raman spectroscopy is also useful in the study of alcohol clusters in the supercritical state [25]. 

As discussed earlier, vibrational spectroscopy in neat water is much more complicated, due to the effects of both intramolecular and intermolecular coupling between OH stretch chromophores. 

Herein we present calculations [6] for liquid H20 that are similar in spirit but different in detail from those of Buch [71, 110] and Torii [97]. The MD simulations are of the SPC/E model [135]. Local-mode anharmonic frequencies are generated from our most recent map developed for the H0D/D20 system [98], as are our transition dipoles. The relatively small intramolecular coupling fluctuates with molecular environment, and is determined by a separate map parameterized from ab initio calculations on clusters. The form of the intermolecular couplings is transition dipole, which is tested and parameterized from additional ab initio calculations. The effects of motional narrowing are taken into account approximately with the TAA [99]. 

We have described our most recent efforts to calculate vibrational line shapes for liquid water and its isotopic variants under ambient conditions, as well as to calculate ultrafast observables capable of shedding light on spectral diffusion dynamics, and we have endeavored to interpret line shapes and spectral diffusion in terms of hydrogen bonding in the liquid. Our approach uses conventional classical effective two-body simulation potentials, coupled with more sophisticated quantum chemistry-based techniques for obtaining transition frequencies, transition dipoles and polarizabilities, and intramolecular and intermolecular couplings. In addition, we have used the recently developed time-averaging approximation to calculate Raman and IR line shapes for H20 (which involves... 

In the spectrum of pure H2O (or D2O), the intermolecular coupling which broadens the free molecule transitions vi and 3 leads to severe overlap of these and (possibly) of the overtone 21 2, thereby complicating interpretation of the observed spectrum. Relatively effective decoupling may be brought about by partial isotopic substitution. In a solution HOD/H2O or HOD/D2O, where either... 

Intra- and intermolecular interaction effects on spin-spin coupling constants... 

Since intermolecular isotope effects were unprecedented in solid-state chemical reactions, a number of experiments were required to show that the results are reproducible and that differences could not be attributed to the history or condition of the crystals, the temperature or extent of photolysis, or differences in the orientation, coupling, absorptivity, or state of com-plexation of C02 dimers between labeled and unlabeled crystals. Success in excluding these alternative interpretations [5] underlines the power of the infrared method, and the special virtues of studying single crystals. 

Thus the SB produced by chemical bonding, intermolecular interactions, and chemical reactions can be regarded as triggered by the same mechanism of JT vibronic coupling effects as in the SB of structural phase transitions in crystals. 

A method enabled for the easy access to titanacycle complexes has been widely developed. Combinations of Cp2TiCl2/2MgBrEt and Cp2TiCl2/2LiBun are effective reagents for the intermolecular coupling of ethylene with... 

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