Polarization-modulated infrared reflection absorption spectroscopy (aided by numerical modeling) is demonstrated as a potentially useful tool for the study of the chemistry of materials growth and processing under steady-state conditions. This approach is applied to a preliminary investigation of the growth of Cr oxide films at low-temperature (less than or equal to 270 degreesC) on Al2O3 using Cr(CO)(6) and O-2. The use of a buried metal layer and of polarization modulation enables detection of surface species with good sensitivity in the presence of strong absorption by gas-phase molecules. Cr(CO)(6) weakly interacting with Al2O3 and Cr oxide surfaces has been observed under equilibrium conditions, and a desorption energy of similar to 11 kcal/mol has been deduced from the temperature-dependent intensity of the upsilon (6)(t(1u)) carbonyl stretching mode. The 735 cm(-1) longitudinal optic mode of Cr2O3 is observed during steady-state growth and simulated using the multilayer Fresnel relations for polarized reflectance. The growth is found to be first order in the Cr(CO)(6) pressure under the present conditions.