Distinguishing surface OH and NHx using TFAA derivatization and XPS

TFAA has been used widely for the derivatization of hydroxyl groups in XPS of organic polymers. Unfortunately, in the presence of other nucleophilic groups at the surface like amino groups, these also react with TFAA and a quantification of the different functional found that the TFAA derivatives of hydroxyl groups and amines, namely the trifluoroacetate and the trifluoroamide, respectively, can be distinguished by the BE of the CF3 component in the C1s spectrum. While in a trifluoroacetamide the BE is about 292.3 eV, in a trifluoroacetate it can be as high as 294.2 eV in the case of densely packed hydroxyl groups.