Deuterium plasma exposure on rhodium: Reflectivity monitoring and evidence of subsurface deuteride formation

► Deuterium plasma exposure of Rh films results in a reversible degradation of the reflectivity. ► Deuterium acts as an electron donor, filling the Rh 4d states above the Fermi level. ► The obtained Rh/D system can be denoted as RhDx. ► After storage in air, initial band structure and reflectivity of Rh are recovered.