We have used gold-, tungsten-, and copper plates to contact repeatedly
a C60 powder sample. We observed the flow of electrons to the sample
leading to negative charge accumulation. In repeated-contact experimen
ts, we find charge saturation after 15 contacts for gold and copper co
ntact partners. This is typical for the behavior of a semiconductor. F
or contact with tungsten however, charge accumulation continues even a
fter 30 contacts. This unusual behavior is explained by the electron s
tate density distribution of C60.