Determination of the molecular arrangement from neutron or X-ray reflectivity

Complete text of publication follows. Neutron and X-ray reflectivity are valuable methods for surface analysis. Since there is no unambiguous relation between reflectivity and scattering length density profile a model with more of less realistic constraints has to be assumed. This led to a variety of fitting methods. So-called 'box-methods' for which the qualitative structure, i.e. the number of boxes and their approximate lengths and heights, of the profile that has to be determined has to be presupposed are especially widespread (see, e.g. [1]). These fitting methods have all in common that they are giving no direct information about the molecular conformation of the system investigated. A new method presented here only requires information about the chemical structure of the molecules involved. For the first time it is now possible to get a direct insight into molecular structure from neutron or X-ray reflectivity data [2]. (author)