Reactive nucleation of silver clusters with oxygen and water

Abstract

The nucleation of silver atoms by the gas aggregation technique when adding O 2 and H 2O molecules in the carrier gas was investigated by photoionization mass spectrometry. No change appeared in the bare silver cluster mass spectra when only water was added to the nucleation carrier gas. In the presence of oxygen and water, reactive nucleation occurred simultaneously. At low reactive gas concentration (unsaturated regime), Ag n O x H y compounds with x=2, 3 and 4 are produced for n⩾6. For a larger reactive gas concentration (saturated regime) two series of cluster bunches having Ag 3O 3H y as the building block were observed. The precursors of these series are (Ag 4O 3H y ) + and (Ag 5O 5H y ) +, respectively. This behavior differs totally from the results obtained for reactive nucleation of an alkaline vapor but can be viewed as a precursor of the surface silver hydroxidation mechanism.