Addition of a single chemical functional group to a polymer surface with a mass-separated low-energy ion beam

A mass-separated low-energy ion beam system was used to deliver pure OH+ and NH+ to 15 nm thick polystyrene films on silicon in ultrahigh vacuum. This was done in an effort to produce specific surface chemical functional groups, X-ray photoelectron spectroscopy showed that when the bombardment energy of OH+ exceeded 10 eV, or the dose was higher than 1 x 10(16) ions cm(-2), a mixture of C-OH, C-C=O and C-COOH groups was produced, along with severe damage to the aromatic rings. However, for bombardment at 10 eV with a dose of 1 x 10(16) ions cm(-2), only C-OH (or COR) groups were found, Similarly, bombardment with NH+ at 10 eV and a dose 1 x 10(16) ions cm(-2) induced incorporation of a single nitrogen-containing functionality, The C 1s data indicated that the major chemical functionality on such surfaces in a C-NH2 (or C-NHR) group with a minor component of C-(NH2)(2). Hence, surface functionality can indeed be controlled by altering the molecular nature, energy and dose of the bombarding species.