The abnormal IR effects (AIREs) characterized by a positive-going peak of platinum (Pt) nanostructured surface generated in a square-wave potential treatment upon CO molecule chemisorptiori was observed and analyzed with a consideration of the interparticle interaction and electron-hole damping between nanoislands and CO molecules: A theoretical simulation shows that the islanded nanostructured Pt surfaces, which gives rise to interparticle interaction, coupling with electron-hole mechanism, may contribute to the origins of positive-going, peak (AIREs) observed by in situ Fourier transformation IR (FTIR) experiments. (C) 2004 American Institute of Physics.