Fig. 7. Ratios of the Chetero to Calkyl (top) and the Canion to Chetero (bottom) peak areas in the C 1s region (80° emission) as a function of the film thickness of [C8C1Im][Tf2N] on Ag(111) at RT. The horizontal lines mark the nominal ratios and the ratios observed for macroscopic films in 80° emission. The deviations of the thick films from the nominal respective ratios are due to a preferential surface enrichment of the alkyl chain of the cation (top) and the CF3 groups of the anion (bottom).
