Cluster, water

The SPC/E model approximates many-body effects m liquid water and corresponds to a molecular dipole moment of 2.35 Debye (D) compared to the actual dipole moment of 1.85 D for an isolated water molecule. The model reproduces the diflfiision coefficient and themiodynamics properties at ambient temperatures to within a few per cent, and the critical parameters (see below) are predicted to within 15%. The same model potential has been extended to include the interactions between ions and water by fitting the parameters to the hydration energies of small ion-water clusters. The parameters for the ion-water and water-water interactions in the SPC/E model are given in table A2.3.2. 

The experimental data and arguments by Trassatti [25] show that at the PZC, the water dipole contribution to the potential drop across the interface is relatively small, varying from about 0 V for An to about 0.2 V for In and Cd. For transition metals, values as high as 0.4 V are suggested. The basic idea of water clusters on the electrode surface dissociating as the electric field is increased has also been supported by in situ Fourier transfomr infrared (FTIR) studies [26], and this model also underlies more recent statistical mechanical studies [27]. 

Figure A3.5.10. Bond strengths of water clustering to various core ions as a fiinction of the number of water molecules.

Lavrich D J, Buntine M A, Serxner D and Johnson M A 1993 Excess energy-dependent photodissociation probabilities for Ot in water clusters O, I 1i Chem. Rhys. 99 5910-16... 

To date, the IR-CRLAS studies have concentrated on water clusters (both FI2O and D2O), and methanol clusters. Most importantly, these studies have shown that it is in fact possible to carry out CRLAS in the IR. In one study, water cluster concentrations in the molecular beam source under a variety of expansion conditions were characterized [34]- hr a second study OD stretching bands in (020) clusters were measured [35]. These bands occur between 2300... 

Paul J B, Collier C P, Saykally R J, Scherer J J and O Keefe A 1997 Direct measurement of water cluster concentrations by infrared cavity ringdown laser absorption spectroscopy J. Phys. Chem. A 101 5211-14... 

Figure Bl.4.8. Top the lowest-energy structures of water clusters, from n = 2 -6. Bottom a sample...

Hydrogen-bonded clusters are an important class of molecular clusters, among which small water clusters have received a considerable amount of attention [148, 149]. Solvated cluster ions have also been produced and studied [150, 151]. These solvated clusters provide ideal model systems to obtain microscopic infonnation about solvation effect and its influence on chemical reactions. 

Figure Cl.3.7. Equilibrium geometries of some water clusters from ah initio calculations. (Taken from 1621.)...

The ultimate reason for studying water clusters is of course to understand tire interactions in bulk water (tliough clusters are interesting in tlieir own right, too, because finite-size systems can have special properties). There has been... 

Xantheas S S 1994 Ab initio studies of cyclic water clusters (HjO), n=1-6. 2. Analysis of many-body interactions J. Chem. Phys. 100 7523-34... 

Bat ii Z and Miller R E 1996 Molecular clusters structure and dynamics of weakly bound systems J. Phys. Chem. 100 12 945-59 Liu K, Cruzan J D and Saykally R J 1996 Water clusters Science 271 929-33... 

Much of tire science of biocompatibility can be reduced to tire principles of how to detennine tire interfacial energies between biopolymer and surface. The biopolymer is considered to be large enough to behave as bulk material witli a surface since (for example) a water cluster containing only 15 molecules and witli a diameter of 0.5 nm already behaves as a bulk liquid [132] it appears tliat most biological macromolecules can be considered to... 

Fig. 5.34 Annular flow in the inclined pipe 25 mm with air-water clusters. Reprinted from Hetsroni et al. (2003b) with permission...

Fig. 5.35a-h Flow regimes in the pipe of 25 mm at f/os = 36 m/s (a) Uis = 0.016 m/s, disturbance waves with motionless droplets (b) Uis = 0.027 m/s, disturbance waves with moving droplets (c) U s = 0.045 m/s, disturbance waves and liquid film on the upper tube part (d) Uis = 0.17 m/s, disturbance air-water waves and liquid film on the upper tube part (e) Uis = 0.016 m/s, small air-water clusters (f) Ui = 0.027 m/s, air water clusters fe) Uis = 0.045 m/s, huge air-water clusters (h) Uis = 0.17 m/s, huge air-water clusters that block the tube cross-section. Reprinted from Hetsroni et al. (2003b) with permission... 

Repeat the runs described above but change the values to hot water, Pb(AA) = 0.8 and J(AA) = 0.25. Notice the change in the water clusters... 

Knowledge concerning the mechanism of hydrates formation is important in designing inhibitor systems for hydrates. The process of formation is believed to occur in two steps. The first step is a nucleation step and the second step is a growth reaction of the nucleus. Experimental results of nucleation are difficult to reproduce. Therefore, it is assumed that stochastic models would be useful in the mechanism of formation. Hydrate nucleation is an intrinsically stochastic process that involves the formation and growth of gas-water clusters to critical-sized, stable hydrate nuclei. The hydrate growth process involves the growth of stable hydrate nuclei as solid hydrates [129]. 

Laasonen, K., Parrinello, M., Car, R., Lee, C., Vanderbilt, D., 1993, Structures of Small Water Clusters Using Gradient-Corrected Density Functional Theory , Chem. Phys. Lett., 207, 208. 

Nielsen, I. M. B., Seidl, E., Janssen, C. L., 1999, Accurate Structures and Binding Energies for Small Water Clusters The Water Trimer , J. Chem. Phys., 110, 9435. 

Chapman RD (2007) Organic Difluoramine Derivatives. 125 123-151 Christie RA, Jordan KD (2005) n-Body Decomposition Approach to the Calculation of Interaction Energies of Water Clusters 116 27-41... 

As the temperature increases from ambient to the critical point, the electrolytic conductance of water rises sharply and is almost independent of the pressure. Macroscopically, this is due to the decrease in water viscosity over this range. The primary cause for the fall in viscosity is a disintegration of water clusters. 

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