Abstract
A regular series of silver-carbon mixed cluster ions: AgmC2n(m=3, 5, 7, 9; n=1, 2, 3) has been found by mass spectrometry. This regularity is not destroyed by the energetic collisions of the cluster ions with argon atoms. Remarkable differences are observed in the chemical species produced between the cluster ions containing odd numbers of silver atoms and those containing even numbers of silver atoms. Size-selected reactions of the cluster ions with argon clearly show the magic numbers effect, in addition to the even-odd difference. The mechanism of formation of silver-carbon mixed cluster ions is studied. The authors propose that the mixed cluster ions are produced on a silver surface through decomposition and dehydrogenation of hydrocarbon molecules contained in the background gas of the ionization chamber. This picture is consistent with observations from scanning tunneling microscopy.
