The surface chemistry of plasma-polymerized acrylic acid (ppAc) films were controlled in a two-stage (primary and processing) hybrid radio frequency (RF) discharge by changing the grid wire spacing (d(s)). Two regions were defined in terms of d(s) with respect to Debye length (lambda(d)) in the primary chamber at the grid to control the electron temperature (T,) and surface chemistry of the ppAc films deposited in the processing chamber. A higher T-e (> 3 eV) in the processing plasma was possible for d(s) > lambda(d), whereas decreasing d(s) relative to lambda(d) reduced T-e. X-ray photoelectron spectroscopy was used to characterize the ppAc films deposited on a glass substrate. The ppAc films surface characterization showed the maximum proportion of carbon atoms as carboxylic/ester [C(=O)OX] functionalities in C1s at the surface of films for the grid with d(s) approximate to lambda(d). The proportion of carbon atoms as -[C(=O)OX] and COX in C1s at the surface decreased when d(s) decreased relative to lambda(d). The proportion of carbon atoms as carbonyl (C=O) at the film surface showed very good stability for all of the d(s) values explored in this study. (c) 2007 Wiley Periodicals, Inc.