Detection of gold cluster ions by ion-to-ion conversion using a CsI-converter

摘要

Gold cluster ions in the m/z range of 10~4-2x10~6 u were produced by bombarding a thin film of gold with ~252Cf-fission fragments. The gold covering a C-Al substrate formed islets having a mean diameter of 44 A. Their size- and mass-distribution was determined by means of electron microscopy. The main task was to measure the m/z distribution of the cluster ions ejected from the sample surface. For this purpose we built a time-of-flight (TOF) mass spectrometer, which could be used as a linear TOF instrument or, alternatively, as a tandem-TOF instrument being equipped with an ion-to-ion converter. combining the results obtained in both modes, it turned out that the linear TOF instrument equipped with micro-channel plates had a mean detection efficiency for 20 keV cluster ions of about 40