DAMAGE TO CF3CONH-TERMINATED ORGANIC SELF-ASSEMBLED MONOLAYERS (SAMS)ON AL, TI, CU, AND AU BY AL K-ALPHA X-RAYS IS DUE PRINCIPALLY TO ELECTRONS

This paper models damage induced by monochromatized A1 Kalpha X-rays t o organic thin films using self-assembled monolayers supported on Al, Ti, Cu, and Au. An X-ray photoelectron spectrometer is used both to co nduct the X-ray irradiation and to analyze the damage. In all cases th ese monolayers comprised a trifluoroacetimido (CF3CONH-) group bound t o the substrate through an undecyl tether to either a chemisorbed thio late or carboxylate. This work extends a previous study of using trifl uoroacetoxy-terminated SAMs on Au and Si. We find the X-ray-induced da mage to the CF3CONH-terminated SAM is first order in the loss of fluor ine. From a comparative study of the loss of fluorine from monolayers formed on these substrates with different electron yields, we show dir ectly that electrons, not X-rays, are the principal cause of damage to the monolayer films. These results are relevant to the design of new materials targeted to fabrication at small dimensions by X-ray or elec tron lithography.