Packed ice particles

The results described above indicate two interesting facts many samples consisting of packed ice particles exhibit a dielectric dispersion of the Davidson-Cole type, and ice samples grown from the vapor phase exhibit a shorter relaxation time r and a lower activation energy of rthan ordinary ice samples grown from the liquid phase. 

A sample consisting of packed ice particles has numerous cavities and ice particle surfaces inside, and the number of dangling bonds oriented with a hydrogen nucleus at the surface of ice tends to increase. Therefore we can expect that the number of L-defects near the ice particle surfaces also tends to increase and protons near the ice particle surface can easily move. The dispersion of the Davidson-Cole type may be caused by proton behaviors near the ice particle surfaces in a sample consisting of packed ice. 

Crushed ice samples. Figure 2 shows the dielectric properties of samples consisting of packed crushed ice particles, which were prepared by crushing single crystal... 

Figure 2 For packed samples of crushed ice particles, (a) Temperature dependence of the dielectric relaxation time rand (h) Cole-Cole plots of the sample (after 400 h of annealing at -1 °C, 2-4 mm particle size, 536 kg/m packed density) at -10 °C. The dielectric dispersion is of the Davidson-Cole type (a=0.97, f=0.85).

Fig. 6.9. Schematic description of the distribution of first- and second-nearest neighbors (a) in water and (b) in a simple fluid. The tetrahedral orientation of the hydrogen bond induces a radial distribution of first- and second-nearest neighbors at a and 1.63cr, respectively, a = 2.76 A being the 0-0 distance in ice If,. The almost equidistant and concentric nature of the packing of particles in a simple fluid produces corresponding neighbors at a and 2a.

Of similar photochemical importance as H2O2 is nitrate, which absorbs light above 290 nm. The ubiquitous presence of nitrate in environmental ices is well documented for cirrus ice particles [296, 297] as well as permanent and perennial snow packs [298-301]. hi aqueous solution, photolysis of nitrate ion leads to either OH and NO2 or 0( P) and nitrite ion, with typically significantly higher quantum yields for the first pathway [197, 200]. In the upper troposphere, it is currently thought that uptake of HNO3 to ice makes it ineffective as a photolytic source of... 

You caimot predict the relative densities of ice and liquid water based on benzene. Ice cubes and icebergs float because water is less dense as a solid than it is as a liquid. Figure 13-17 shows the reason for the exception. The water molecules in ice are less closely packed together than in liquid water that is, there is more space between the molecules in ice. As a result, there are more particles per unit volume in liquid water than in solid water. 

Crystalline solids Although ice is unusual in its density, ice is typical of most solids in that its molecules are packed together in a predictable way. A crystalline solid is a solid whose atoms, ions, or molecules are arranged in an orderly, geometric structure. The locations of particles in a crystalline solid can be represented as points on a framework called a crystal lattice. Figure 12.19 shows three ways that particles in a crystal lattice can be arranged to form a cube. 

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