The authors focus on thermal and nonthermal (radiation-induced) surface processes that affect the reflectivity of TiO2-capped multilayer mirrors used in extreme ultraviolet (EUV) lithography. Low energy electron beams mimic excitations initiated by EUV radiation. Where appropriate, comparison is made with electron bombardment in the vapor of methyl methacrylate (C5H8O2). Benzene adsorbs and desorbs reversibly on TiO2, and the steady state coverage Theta is found to be proportional to the logarithm of the benzene pressure p. This behavior is described by the Tempkin adsorption isotherm, which has the form Theta=const+log p. This isotherm is a consequence of a linear dependence of benzene adsorption energy on Theta. In addition, measurements of cross sections sigma (cm(2)) for electron-stimulated dissociation of benzene on clean and C-covered TiO2 in the range of 10-100 eV reveal surprisingly large values (e.g., similar to 3.5x10(-17) cm(2) at 10 eV primary energy). Thus, low energy secondary electrons excited by EUV lithography photons are expected to contribute substantially to carbon accumulation on clean TiO2 cap layers.