A novel resonant mechanism involving the interference of a broadband plasmon with the narrowband vibration from molecules is presented. With the use of this concept, we demonstrate experimentally the enormous enhancement of the vibrational signals from less than one attomol of molecules on individual gold nanowires, tailored to act as plasmonic nanoantennas in the infrared. By detuning the resonance via a change in the antenna length, a Fano-type behavior of the spectral signal is observed, which is clearly supported by full electrodynamical calculations. This resonant mechanism can be a new paradigm for sensitive infrared identification of molecular groups.

Rayleigh instability of copper nanowires has been experimentally demonstrated. After annealing $30–50\text{-}\mathrm{nm}$ -diam wires at temperatures between 400 and $600°\mathrm{C}$ , different stages of the fragmentation process are observed by scanning electron microscopy. At $400°\mathrm{C}$ , the wires start to fragment, forming shorter sections at $500°\mathrm{C}$ , and finally decaying into a chain of nanospheres at $600°\mathrm{C}$ . Average diameter and spacing of the spheres are in agreement with theoretical predictions. The Rayleigh instability applied to nanowires provides a structuring technique producing long chains of nanospheres, which should find interesting applications, for instance, by guiding light below the diffraction limit via coherent coupling of surface-plasmon polaritons.

With infrared spectroscopic microscopy using synchrotron light, the authors studied resonant light scattering from single metal nanowires with diameters in the $100\mathrm{nm}$ range and with lengths of a few microns. The Au and Cu nanowires were electrochemically grown in polycarbonate etched ion-track membranes and transferred on infrared-transparent substrates. Significant antennalike plasmon resonances were observed in good agreement with exact light-scattering calculations. The resonances depend not only on length and diameter but also on the dielectric surrounding of the nanowire. The observed maximum extinction at resonance corresponds to an electromagnetic far-field enhancement by a factor of about 5.

A new method for the measurement of thermal conductivity of electrically conducting single nanowires is presented. First experimental investigations are focused on the thermal conductivity of metallic Pt nanowires with a diameter of (typically) 100 nm and a length of 10 microm. Thermal conductivity data are compared with measurements of electrical conductivity in order to test the Wiedemann-Franz law for metallic nanowires. Compared to the bulk values at room temperature, electrical and thermal conductivities of the nanowire are decreased by a factor of 2.5 and 3.4, respectively. Consequently, the Lorenz number L = lambda/sigmaT = 1.82 x 10(-8) V(2) K(-2) of the nanowire is smaller than the bulk Lorenz number L(bulk) = (pi(2)/3)(k/e)(2) = 2.44 x 10(-8) V(2) K(-2) of metals. Furthermore, the temperature coefficient beta of electrical resistivity is also reduced compared to the bulk value. These decreases of lambda, sigma and beta can be attributed to size effects, mainly caused by grain boundary scattering of electrons.