To examine the stability of prototypes of the kilogram after cleaning, surface analysis techniques, including X-ray photoelectron spectroscopy (XPS), were applied to specimens cut from prototype material of Pt-10 % Ir alloy. Traditional steam-jet cleaning (SJC) was compared with ultrasonic cleaning with solvents (UCS) in terms of cleaning effects and the progress of contamination. The results show that mass changes due to metallic factors such as oxidation, reduction and dissolution were negligibly small. In terms of carbon decrease and adsorption of water, UCS was superior to SJC. From analyses of peak area ratio by XPS, it was shown that the cleaner the surfaces, the higher the rate of contamination. But the contamination levels converged to a common value after a six-month exposure to air, irrespective of the cleaning method used. This finding is of great importance for the preservation of prototypes. The contaminating substances were found to be hydrocarbons from the ambient air. The mass gain for the surfaces of a prototype due to hydrocarbons after a six-month exposure to ambient air is estimated to be 4,3 pg for SJC and 16 pg for UCS.
We have investigated the dynamics of gas discharge around drops of conducting (strong electrolytes) and nonconductive (organic oils) liquids. The trend of dynamics of the gas discharge image turns out to distinquish even between chemically close liquids, which have nondistinquishable static gas discharge images. This article is a natural continuation of the work by K. Korotkov and D. Korotkin [J. Appl. Phys. 89, 4732 (2001)], where static images of gas discharge were studied.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.