  In this paper, the effect of air exposure and acetone cleaning on the
secondary electron yield (SEY) of laser treated copper were investigated and
discussed. The SEY of laser treated copper samples after acetone cleaning and
air exposure were measured. After 10 to 21 months air exposure, the maximum SEY
increased by about 11%~20%. Furthermore, changes of carbon, copper, and oxygen
chemistry states from sample surface after acetone and air exposure were
studied by means of XPS. The XPS results show that the concentration of Cu
decreased by about 61%~70% after acetone cleaning and decreased by a further
36%~70% after 10 to 21 months air exposure. Moreover, the XPS measurement
reflects the significant increase of the total percentages of C and O after
acetone cleaning, and further increase after 10 to 21 months air exposure. The
increase of SEY is explained in terms of the introduction of impurities, such
as oxide, carbide etc.
