What are the Special Characteristics of Organic Solids

In solids, one can distinguish four essential types of bonds ionic bonds, metallic bonds, covalent bonds, and van der Waals bonds. In addition, in rare cases, hydrogen bonding is observed it is indeed especially important in bio-macromolecules. 

A notable measure of the intermolecular forces is the maximum frequency v of the lattice vibrations (optical phonons). In a typical organic molecular crystal, it is of the order of 3.5 THz in Si, in contrast, it is 14THz. Thus the difference in the Boltzmann factors exp(-hv/feT) for the thermal occupation of phonon states, which plays a decisive role in many solid-state properties, is already great when comparing organic and inorganic solids at room temperature, and it becomes very much greater at low temperatures (Table 1.2). 

Precisely those solid-state properties which are due to the relatively weak mutual bonding of the molecules in the crystal are what make the organic solids so interesting. This is the topic of the present book. 

There are a whole series of properties and problems which distinguish the organic molecular crystals in characteristic ways from other soHds and make them 

First of all, we consider the surfaces Due to the short range of the interaction forces, one can more readily produce surfaces and interfaces of high quality, with low defect and impurity concentrations, than in other types of crystals. 

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