Chapter 14 Gold nanorods: preparation, characterization, and applications to sensing and photonics

Abstract

Rod-like gold nanoparticles (gold nanorods: AuNRs) show unique optical properties depending on the size and the aspect ratio (the ratio of longitudinal-to-transverse length). Although the spherical gold nanoparticle (nanosphere) has only one surface plasmon (SP) band in the visible region, the NR has a couple of SP bands. One SP band corresponding to the transverse oscillation mode locates in the visible region at around 520 nm, while the other corresponding to the longitudinal oscillation mode between far-red and near-infrared (near-IR) region. This is the distinctive optical characteristic of the NR as compared with the nanosphere. In spite of such unique optical property, the NR had not been utilized for scientific and technological fields, because of the absence of high-yield synthetic methods with desirable size and aspect ratio. Recently, however, owing to the recent reports on high-yield preparation methods of tailor-made AuNRs, extensive applications of the NRs have just started in various fields. This chapter describes recent progress about the preparation, characterization, and optical and technological applications of the NRs with mainly focusing on studies.