UV/ozone cleaning of mass standards: results on the correlation between mass and surface chemical state

摘要

UV/ozone cleaning of 1 kg Au and steel mass artefacts was studied by direct mass comparison and surface chemical analysis by XPS. Both materials are oxidized with an increasing oxide layer thickness upon prolonged exposure time. The gain in mass is significant. The gold oxides are not stable and decompose with time in part at ambient. As shown for artefacts of stacked discs, cavities and interspaces were also cleaned, but with a much longer cleaning time. Stacked discs, having a completely different cleaning time, are questionable for the determination of sorption phenomena.