STRAIN-MODULATED REFLECTIVITY OF LUTETIUM

We report strain-modulated-reflectivity measurements on lutetium in the energy range 1.5-6 eV. In order to avoid the effects of oxidation, the measurements were performed in an UHV chamber on polycrystalline films deposited in situ onto a quartz-crystal strain transducer. Measurements taken with light polarized parallel and perpendicular to the major strain axis of the transducer have been analyzed to obtain the hydrostatic-strain derivative of the dielectric function by using an isotropic approximation. Several critical-point structures can be identified, and the average deformation potential for sp- to d-band transitions is measured to be -6 eV per unit hydrostatic strain. The results show general agreement with calculated band structures.