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 (≤270 °C) on Al2O3 using Cr(CO)6 and O2. 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 ∼11 kcal/mol has been deduced from the temperature-dependent intensity of the v6(t1u) 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.