Energy Redistribution Between Quasiparticles in Mesoscopic Silver Wires

We have measured with a tunnel probe the energy distributionfunction of quasiparticles in silver diffusive wires connectedto two large pads (“reservoirs”), between which a biasvoltage was applied. From the dependence in energy and biasvoltage of the distribution function we have inferred theenergy exchange rate between quasiparticles. In contrast withpreviously obtained results on copper and gold wires, thesedata on silver wires can be well interpreted with the theoryof diffusive conductors either solely, or associated withanother mechanism, possibly the coupling to two-level systems.