Resonances of individual lithographic gold nanowires in the infrared

With infrared spectroscopic microscopy using synchrotron radiation, we systematically studied resonant light scattering from electron-beam lithographically produced gold nanowires (nanostripes) with diameters in the 100 nm range and with various lengths below 1 to about 2.5 μm. Similar to electrochemically grown cylindrical wires of high crystalline quality, clear antennalike plasmon resonances were observed for these stripelike and less-perfect wires. The resonance wavelength shifts with length as theoretically predicted for cylindrical gold antennas in the optical range. Surprisingly, also the extinction cross section of the nanostripes is equal to that measured for highly crystalline cylinders.