Ellipsometric and electron spectroscopic study of degradation of optical properties in Mo mirror irradiated with deuterium and/or helium ions

Degradation of optical properties in Mo mirrors irradiated with helium and/or deuterium ions has been studied by ellipsometric spectroscopy, electron energy loss spectroscopy, and electron microscopy. It was found that values of the optical constants (reflectivity, refractive index, and extinction coefficient) of the specimens decreased in the order of deuterium, deuterium and helium dual-beam, and helium irradiations. The penetration depth of the laser light in the specimen, estimated from the observed extinction coefficient, increased in the same order.