Intensity variation dependence of secondary ion emission of carbon clusters from graphite, diamond-like carbon and diamond surfaces on number of carbon atoms

Secondary ions of carbon clusters from graphite, diamond-like carbon (DLC) and diamond have been investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). A series of negative carbon cluster ions Cn-(n=1-15) were observed. Considering the electron affinities (EA) of the clusters, the dependence of the intensities on the value of n was analyzed using multiple regression analyses. After subtracting the influence of EA, the slopes of the lines in the range of C1--C9- were obtained. The slope was shown to be higher for graphite than for diamond. DLC shows almost similar behavior as diamond. These results indicate that negative carbon cluster ions in TOF-SIMS can be strongly correlated with the matrix.