Understanding the relationship between the atomic structure and the physical properties of materials is a key foundation for the field of material science. Nondestructive techniques to determine the structure of materials have vastly improved over the past few decades. In particular, the development of synchrotron sources which produce high intensity x-rays has enabled the structural determination of nanoscale systems with picometer (10-12m) scale resolution. This talk will illustrate the application of synchrotron diffraction to elucidate the atomic structure and polarization of ultrathin oxide films grown by molecular beam epitaxy. The results are used to understand the origin of polarization coupling between film and substrate and have provided guidance for the development of novel electronic devices.