Optical effects of energetic copper-ion irradiation on copper mirrors

The optical effects of radiation damage to metal mirrors have been examined using copper-ion beams incident on copper mirrors. Incident ion energies of 2, 5, and 8 MeV were used and dose levels were examined up to 4 x 10(16) ions/cm(2). Both crystalline and OFHC copper mirrors were studied. In situ ellipsometric data were recorded (lambda = 633 nm) during the irradiations to determine the dose-dependent behavior of the radiation effects. Spectral reflectivity and optical scattering were evaluated for samples before and after the irradiations. Complementary analysis of the samples was performed with scanning electron microscopy, Auger electron spectroscopy, and electron spectroscopy for chemical analysis. Significant changes in ellipsometric parameters were noted during the irradiations. After exposure to large dose values, the optical properties of crystalline mirrors were consistent with the optical properties of bare copper. The ellipsometric changes have been attributed to alteration of the surface oxide film. Dose-dependent data have been used to determine the important damage mechanisms.