The surfaces of nanostructured, porous SiOx/Si (air-oxidized Si) and SiOx thin films, deposited by excimer laser ablation in He and He + O-2 gas ambients, respectively, have been modified by the deposition of a monofunctional organosilane. They were characterized using photoacoustic Fourier-transform infrared (FTIR) X-ray photoelectron (XPS) spectroscopies, and field-emission scanning electron microscopy (FESEM). Photoacoustic FTIR analysis indicates that the organosilane has hydrolyzed to form a silanol, which has chemically reacted with SiOx through its surface silanol (-SiOH) group, to form siloxane (Si-O-Si) structures. An enhanced IR spectral signal is found, due to the expansion and contraction of both the pores of the solid and the gas within them. (c) 2005 Elsevier B.V. All rights reserved.