The quantitative effect of thermal treatment on the secondary electron yield from air-exposed silver surface

Air-exposed silver surface is investigated in a multifunctional ultrahigh vacuum system to find out the quantitative relation between thermal treatment and the electron-induced secondary electron yield (SEY). Silver-coated samples are heated in the range of about 100-320 °C for up to 120 min, and thermal desorption is characterized. The SEY is then measured in situ as a function of primary electron energy. The maximum SEY is found to decrease almost linearly with the increase in the logarithmic thermal desorption amount determined by the heating time in a designed process. Reduction of SEY also shows a linear relationship with sample temperature in the observed range. Residual gas analysis demonstrates that the SEY reduction depends strongly on the rapid water desorption. In combination with the results of Ar-ion cleaning and Monte Carlo simulation, this work provides a new insight into the SEY variation due to surface desorption of different gases.