The chemistry of perfluorobutyl iodide (C4F9I) on I-I-free and II-terminated diamond (110)-oriented surfaces was investigated using multiple internal reflection infrared spectroscopy (MIRIRS). C4F9I physisorbed to form multilayers at 90 K for both surface terminations. The physisorbed C4F9I desorbed from the surface when heated above 200 K and the starting surface was regenerated. The electronic structure and vibrational spectra of the perfluorobutyl group were calculated for perfluorobutyl chloride and perfluorobutyl bromide and the MIRIRS of the physisorbed multilayer agreed well with calculated infrared spectra. After exposing the C4F9I multilayer at 90 K to UV radiation for 30 min and subsequently heating thp surface above 200 K characteristic vibrational features of the perfluorobutyl group were observed between 1138 and 1355 cm(-1) In a series of annealing experiments, these modes persisted on the surface up to 600 K and completely disappeared by 700 K. The same results were observed on both the H-free and H-terminated surfaces.