Measurements of the normal-incidence electroreflectance of clean, strain-free single crystals of Ag and Au with use of a novel drop-electrolyte technique shown an anisotropy on the (110) face of Ag which is not present on Au. It can be explained by field-induced indirect interband transitions which are observed in Ag but not in Au. This work shows that part of the electroreflectance spectrum of Ag arises from electrons which interact with the periodic crystal potential.

• Received 30 June 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.960