Identification of mercury reaction sites in fluorescent lamps

The interaction between Hg and components in fluorescent lamps was studied using electron spectroscopy for chemical analysis (ESCA) and sputtered neutral mass spectrometry (SNMS). Active sites, which were responsible for Hg interaction/deposition, were identified by comparison of the X-Y distribution (obtained by ESCA mapping) and depth distribution (available through SNMS) of respective lamp components with that of Hg. These results showed that Hg strongly interacted with Na (from glass) and the emitter components, especially Ba. in the case of lamps with a tin oxide conductive film, the film was also a source for interaction. Exact assignment of the oxidation state for the interacted Hg species was not certain due to a small variation in binding energy shift among the Hg compounds. However, the data suggested an Hg(0) state. It was possible that most of the Hg species strongly chemisorbed onto Ba (and/or Sr) and Na sites or formed intermetallic compounds with these elements. (C) 1999 The Electrochemical Society. S0013-4651(99)03-097-9. All rights reserved.