Comparative surface investigations at spherical Si surfaces using optical and X-ray techniques

Currently options for a new definition of the kilogram on the basis of invariants of nature are under investigations. One of the most promising approaches uses the mass of ¹²C. Within the framework of the Avogadro project the scaling factor between atomic mass units and macroscopic mass, the Avogadro constant N_A, will be measured with a relative standard uncertainty 2·10^-8, to enable this type of realization.