Photovoltaic effect in cuprous oxide-copper junctions in relation to the optical absorption spectrum of cuprous oxide

The spectral dependence of the photovoltaic effect (PVE) of Cu₂O-Cu cells, annealed in three distinct ways, was measured. The copper contact was formed by high temperature reduction of the surface of the oxide. The measurements were made for different thicknesses of oxide, and with front wall and back wall illumination. Two types of absorption constant were calculated from PVE measurements and compared with directly measured absorption constants from transmission data. The results allow us to distinguish between electronically active absorption near the bandgap and electronically inactive absorption at longer wavelengths.     

Evidence of a competitive phenomenon between the 0.72 μm and 0.93 μm luminescences of Cu2O

Luminescence studies after excitation by a frequency doubled Nd : YAG laser showed evidence of competition between the 0.72 μm and 0.93 μm extrinsic luminescences in Cu₂O. The luminescence outputs of 0.72 μm and 0.93 μm were observed as a function of temperature at various laser intensities. The data suggest attenuation of 0.93 μm with the onset of 0.72 μm. This phenomenon has never been reported in the literature and represents a departure from the conventional theories on the luminescence of cuprous oxide.     

Second-sound spectroscopy of a nonequilibrium superfluid-normal interface

An experiment is proposed to test a previously developed theory of the hydrodynamics of a nonequilibrium heat current-induced superfluid-normal interface. It is shown that the interfacial "trapped" second-sound mode predicted by the theory leads to a sharp resonant dip in the reflected signal from an external second-sound pulse propagated toward the interface when its horizontal phase speed matches that of the interface mode. The influence of the interface on thermal fluctuations in the bulk superfluid is shown to lead to slow power dependence of the order parameter, and other quantities, on distance from it.     

Universal early-time response in high-contrast electromagnetic scattering

The time-domain response of highly conducting targets following a rapidly terminated electromagnetic pulse displays three distinct regimes: early, intermediate, and late time. The intermediate and late times are characterized by a superposition of exponentially decaying eigenmodes. At early time an ever increasing number of rapidly decaying modes contribute, with the result that the scattered electric field displays a universal t(-1/2) power law which emerges from the diffusive decay of a pattern of surface currents induced by the pulse. The power law amplitude reflects the surface geometry of the target, a property that may prove useful in buried target classification in geophysical remote sensing applications.