Imaging of Surface Plasmon and Ultrafast Dynamics in Gold Nanorods by Near-Field Microscopy

We investigated the near-field optical properties of single gold nanorods. Transmission images observed near the surface plasmon resonances agree qualitatively with the calculated maps of the optical local density of states and are reflected by spatial characteristics of plasmon wave functions. Ultrafast temporal responses have been observed by combining near-field microscopy with a time-resolved technique. It has been found that the behavior of the collective motion of electrons in the center of the rod is different from that in both ends.