Molecular surface structure of tetracene mapped by the atomic force microscope

The atomic force microscope has been used to record molecular structure on free-standing organic crystals. A crystal of tetracene has been imaged with molecular resolution which allows the assignment of lattice parameters to the surface layer. The intermolecular spacings on the surface of tetracene correspond remarkably closely with those in the bulk. It is even possible to distinguish between the two translationally inequivalent molecules of the unit cell. The mechanism for using force microscopy to distinguish between different molecular orientations is discussed.