International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

International Tables for Crystallography (2006). Vol. C, ch. 3.5, p. 176

Section 3.5.3.3. Oriented solidification

N. J. Tighe,a J. R. Fryerb and H. M. Flowerc

a42 Lema Lane, Palm Coast, FL 32137-2417, USA,bDepartment of Chemistry, University of Glasgow, Glasgow G12 8QQ, Scotland, and cDepartment of Metallurgy, Imperial College, London SW7, England

3.5.3.3. Oriented solidification

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Long-chain compounds, paraffins, phospholipids, etc., can be prepared epitaxically from solution in molten naphthalene or benzoic acid (Fryer, McConnell, Dorset, Zemlin & Zeitler, 1997[link]; Wittmann & Lotz, 1990[link]). For example, a dilute solution of a compound in naphthalene is alternatively solidified and liquified within a few degrees of the melting point to order the long-chain material relative to the naphthalene. When finally solidified, the compound is ordered along the (110) plane of the naphthalene. In practice, the final solidification is carried out on a carbon film and the naphthalene is removed under vacuum. The crystals are lath shaped and are aligned with the long-chain major axis on the carbon film across the lath and hence normal to the electron beam. Crystals of the same compounds prepared from normal organic solvents as described in Subsection 3.5.3.2[link] have the long-chain axis normal to the carbon-grid plane and thus parallel to the electron beam. The advantage of the normal orientation is that the large interplanar spacing along the chain axis is more accessible to direct imaging in the electron microscope.

References

Fryer, J. R., McConnell, C. H., Dorset, D. L., Zemlin, F. & Zeitler, E. (1997). High resolution electron microscopy of molecular crystals. IV. Paraffins and their solid solutions. Proc. R. Soc. London, A453, 1929–1946.
Wittmann, J. C. & Lotz, B. (1990). Epitaxial crystal growth on organic and polymeric substrates. Electron Crystallography of Organic Molecules, edited by J. R. Fryer & D. L. Dorset, pp. 241–254. Dordrecht: Kluwer Academic Publishers.








































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