Classification of 2D-GIWAXS Images of Highly Textured Molecular Thin Films Towards Indexation: Triclinic Lattices

Low-symmetry triclinic lattices, as formed by molecular thin films, are conveniently characterized by grazing-incidence wide-angle X-ray scattering (GIWAXS). These films are often highly textured with a specific crystallographic plane (HKL) parallel to the surface and thus form uniaxial powders. A classification scheme is presented that lays the groundwork for determination of the surface unit cell and indexing such complex scattering images. After identifying a first surface unit cell, methods are discussed for normalizing the lattice constants and further reduction of the unit cell.