Hydrogen bonds Raman scattering

Marzocchi M P, Mantini A R, Casu M and Smulevich G 1997 Intramolecular hydrogen bonding and excited state proton transfer in hydroxyanthraquinones as studied by electronic spectra, resonance Raman scattering, and transform analysis J. Chem. Phys. 108 1-16... 

P. Zielke and M. A. Suhm, Concerted proton motion in hydrogen bonded trimers A sponta neous Raman scattering perspective. Phys. Chem. Chem. Phys. 8, 2826 2830 (2006). 

Besides the peaks of the local proton modes typical for hydrogen bond, a sharp peak at 28 meV was observed in KDP [34] and attracted much attention [34,38,39]. This peak exists in DKDP at somewhat higher frequency its intensity decreases in both crystals and its width decreases upon the transition from the FE to the PE phase, without any softening of its frequency [38]. Hence, it is concluded that this mode is connected with the phase transition dynamics, i.e., coupled to the polarization fluctuations. This mode is not the tunneling mode or any local mode of proton or deuteron, but rather some collective optical mode of the lattice that involves substantial proton or deuteron displacement. It has been suggested [38] that this mode corresponds to the mode that has a peak at about 200 cm (25 meV) in Raman scattering and infrared reflectivity spectra, and that it is coupled to the soft mode and usually... 

Raman spectra). The lifetime of the clusters is of the order 10"n to 10-12 s, so that by superimposing many representations of the V-structure we obtain the D-structure. The co-operative hydrogen bonding may be one reason for the differences between relaxation times obtained by different techniques (Frank, 1973) so comparison between experiment and theory is not straightforward. However, X-ray scattering data show that water does not exist as distinct patches of dense and bulky water. Consequently considerable interest has been shown in interstitial models for water (Samoilov, 1965). 

Another effect of hydrogen in crystalline silicon is to break Si—Si bonds. After exposure of the surface to atomic hydrogen, extended defects are found in the surface region, typically to a depth of about 1000 A (Johnson, Ponce, Street and Nemanich 1987). These defects have no Burgers vector and are therefore not dislocations, but rather appear to be microcracks, in which the (111) planes of the crystal are pushed apart. A plausible explanation of the crack is that the silicon atoms are terminated by hydrogen and so are pushed apart. The presence of Si—H bonds is confirmed by Raman scattering. Hydrogen therefore can break Si—Si bonds and has a tendency to disorder the crystal. 

In the present paper we describe the results of X-ray and TOF neutron diffracBon and Raman scattering measurements for aqueous sulfuric acid soluBons with extended composIBon range in order to obtain the intermaBon both on the intermolecular hydrogen-bonded stmcture and on the intramolecular stmctural parameters of SO4 unit in the solutions. 

Hon X, Wu L, Xu W, Qin L, Wang C, Zhang X, Shen J (2002) Self-assembly and Langmuir-Blodgett (LB) film of a novel hydrogen-bonded complex a surface enhanced Raman scattering (SERS) study. Colloids Surf A 198-200 135-140... 

Further H/D isotopic effects are (i) the increased intensities and decreased halfwidths of D2O (and HDO) bands compared to those of H2O in both the Raman and infrared spectra, and (ii) possible deviations from random distribution of H and D in partially deuterated specimens. From the relative intensities of the two OD (and OH) bands of HDO molecules in hydrates with strongly distorted water molecules (see Sect. 4.2.2) it is assumed that the hydrogen and deuterium atoms are not randomly distributed over the two H positions, but the deuterium atoms rather prefer those positions which are involved in stronger (weaker ) H-bonds. For theoretical studies of the i.r. absorption and Raman scattering intensities of free H2O, HDO, and D2O see Refs. 77,152. 

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