Spectral densities of Kondo impurities in nanoscopic systems

We present results for the spectral properties of Kondo impurities in nanoscopic systems. Using Wilson's renormalization group we analyze the frequency and temperature dependence of the impurity spectral density for impurities in small systems that are either isolated or in contact with a reservoir. We have performed a detailed analysis of the structure of the impurity spectral density for energies around the Fermi energy for different Fermi energies relative to the intrinsic structure of the local density of states. We show how the electron confinement energy scales introduce new features in the frequency and temperature dependence of the impurity spectral properties.