Crystalline material

Hf02 Monoclinic, site 1 OHf4 266 Bastow Stuart (1990) 

which is much more electronegative than the other metals, has a much larger xq value ( 7 MHz) (Turner et al. 1985). On the basis of a larger data set, a more general correlation of 8 with the cationic radius has been suggested  

Although it is not obvious how to rationalise these correlations, they provide guidance to the variations expected in such compounds. In a similar way, Xq values for have been correlated with the bond ionicity as the bond becomes more ionic the oxide ion becomes more 0 -like and the field gradient decreases according to 

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CgH,5N02. Colourless crystalline material m.p. 203 C. The major portion of the cocaine molecule, from which it may be obtained by hydrolysis with acid. Benzoylation and methyl-ation reconvert it to cocaine. Forms a stable hydrochloride, m.p. 246 C. See cocaine. 

Ni(NH4)2(S04)2,6H20. Blue-green crystalline material formed from a solution of the components. Used in electroplating. 

A belief that solid interfaces are easier to understand than liquid ones shifted emphasis to the former but the subjects are not really separable, and the advances in the one are giving impetus to the other. There is increasing interest in films of biological and of liquid crystalline materials because of the importance of thin films in microcircuitry (computer chips ), there has been in recent years a surge of activity in the study of deposited mono- and multilayers. These Langmuir-Blodgett films are discussed in Section XV-7. 

The illustrative data presented in Table VII-3 indicate that the total surface energy may amount to a few tenths of a calorie per gram for particles on the order of 1 /xm in size. When the solid interface is destroyed, as by dissolving, the surface energy appears as an extra heat of solution, and with accurate calorimetry it is possible to measure the small difference between the heat of solution of coarse and of finely crystalline material. 

Waseda Y 1980 The Structure of Non-Crystalline Materials (New York McGraw-Hill)... 

Ultra-high vacuum (UHV) surface science methods allow preparation and characterization of perfectly clean, well ordered surfaces of single crystalline materials. By preparing pairs of such surfaces it is possible to fonn interfaces under highly controlled conditions. Furthennore, thin films of adsorbed species can be produced and characterized using a wide variety of methods. Surface science methods have been coupled with UHV measurements of macroscopic friction forces. Such measurements have demonstrated that adsorbate film thicknesses of a few monolayers are sufficient to lubricate metal surfaces [12, 181. 

Kokotailo G T and Meier W M 1980 Pentasil family of high silica crystalline materials The Properties and Appiications ofZeoiites (Speciai Pubiication No. 33) ed R P Townsend (London The Chemical Society)pp 133-9... 

When crystallisation is complete, the mixture of crystals and crude mother-liquor is filtered at the pump, again using a Buchner funnel and flask as described on p. 10, and the crystals remaining in the funnel are then pressed well down with a spatula whilst continual suction of the pump is applied, in order to drain the mother-liquor from the crystals as effectively as possible. If it has been found in the preliminary tests that the crystalline material is almost insoluble in the cold solvent, the crystals in the... 

C. Pisani, Quantum-Mechanical Ah Initio Calculation of the Properties of Crystalline Materials Springer-Verlag, New York (1996). 

An ion-selective electrode based on a sparingly soluble inorganic crystalline material. 

Figure 8.35 Interference between scattered pbotoelectrons in (a) a gaseous diatomic molecule and (b) a crystalline material...

The EXAFS technique is used primarily for investigations of disordered materials and amorphous solids. Figure 8.35(b) shows how interference occurs between the wave associated with a photoelectron generated on atom A and the waves scattered by nearest-neighbour atoms B in a crystalline material. 

In the discussion in Section 9.1.6 of harmonic generation of laser radiation we have seen how the high photon density produced by focusing a laser beam into certain crystalline materials may result in doubling, tripling, etc., of the laser frequency. Similarly, if a laser beam of wavenumber Vl is focused into a cell containing a material which is known to absorb at a wavenumber 2vl in an ordinary one-photon process the laser radiation may be absorbed in a two-photon process provided it is allowed by the relevant selection rules. 

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