Alignment of AFM images using an iterative mathematical procedure
An iterative mathematical procedure for the alignment of sequentially recorded atomic force microscope images (AFM) is presented. The computer program is able to correct commonly observed drifts in vertical and lateral directions, rotations around a vertical or lateral axis and differences in scale. This method is applied on dissolution experiments of uranium dioxide (UO2) surfaces. Images recorded during in situ experiments, which are shifted probably due to thermal fluctuations, can be aligned with good accurancy. In a further approach the UO2 surface is marked by electron-beam-induced deposition (EBD or EBID) with microstructured reference points. The alignment can be distinctly improved using marked sample surfaces because of the characteristic shape of the markings, which do not change during the experiment. Furthermore, the markings can be used to find again a domain on a sample surface. Therefore, AFM images recorded before and after an ex situ experiment (e.g. treatment in corrosive medium for a longer period of time) can be aligned with a nanometer spatial resolution.