Absorption bands of gadolinium in the ferromagnetic and paramagnetic states

The optical constants of gadolinium have been measured by internal reflection from evaporated films on silica glass prisms, at 293 °K and 105 °K, in the spectral region 0·50 to 5·6 eV. Absorption bands were observed at 0·70 eV and 1·1 eV in the ferromagnetic state. No evidence of absorption bands owing to transitions of f electrons was found. An extrapolation of the room temperature data to low energies suggests a value of 0·5 for the effective number of free electrons per atom.