Stress-induced optical anisotropy in polycrystalline copper studied by reflection anisotropy spectroscopy.

The optical properties of polycrystalline copper subjected to tensile stress are monitored in situ and in real time using reflection anisotropy spectroscopy (RAS). It is shown that RAS allows investigation of the plastic regime. Here, in contrast to the Hooke's law regime, the stress-induced RAS lineshape is found to be dependent on the applied stress. The optical anisotropy in the visible region of the electromagnetic spectrum is directly proportional to the mechanical strain. An intense RAS peak observed at a photon energy of 4.0 eV is observed to saturate at a stress approximately equal to the yield stress of copper. This work demonstrates the potential of RAS as a nanomechanics monitor of materials under mechanical stress. [ABSTRACT FROM AUTHOR]