Infrared polarization spectroscopy of the stretching motion of physisorbed CO2 has been used as a probe for the heterogeneity of hydrogen-terminated diamond single crystal surfaces. At the substrate temperature of 83 K, band shape, photometry, and isotherm measurements all indicate that the CO2 molecules are first adsorbed on defect sites, followed by adsorption on terraces that yields a single sharp spectral feature at 2333 cm(-1) with FWHM=6 cm(-1). Nearly 20% of the surface sites on the as-polished C(111)-1x1:H surfaces are defects (C) 1995 American Institute of Physics.