Absolute charge collection efficiencies of undamaged and radiation damaged MOS capacitors have been measured as a function of applied collection bias and related to device damage. The measurements were performed on devices irradiated to various particle fluences, under different bias conditions, and with both lightly and heavily damaging particles. The measurements allow characterization and separation of damage effects due to flatband voltage shifts and atomic displacements in the substrate, and are sensitive indicators of both kinds of damage. Using this technique in conjunction with a microbeam, possibilities exist for investigating damage at a highly localized level, ion per ion, as the damage occurs. This technique is not limited to MOS devices.