Azimuthal dependent reflection anisotropy spectroscopy of Ag(110) near the plasmon resonance energy

The reflection anisotropy (RA) of Ag(110) has been investigated near 3.9 eV as a function of azimuthal angle theta using a photoelastically modulated spectrometer. At 3.9 eV the RA signal was small and varied as sin 4 theta. At photon energies away from 3.9 eV the signal increased and varied as cos 2 theta. Jones vector modeling of the system showed that in addition to the commonly observed cos 2 theta dependence, which disappears when the reflection is isotropic, there is a sin 4 theta dependence that occurs when the underlying dielectric function is anisotropic; in cubic materials this term is small but for other materials it may be very large.