Light Driving and Monitoring Growth of Single Gold Nanorods

Growth processes of single gold nanorods (AuNRs) on a glass coverslip surface were monitored in situ via photoluminescence and dark-field scattering spectroscopy. We found that the growth of gold nanorod (AuNR) was light driven and the growth rate was dependent on the excitation light power and polarization. Specifically, the AuNRs can regrow to a larger size upon intense light irradiation, even if the AuNRs have reached an equilibrium state in original growth solution. Furthermore, the resonance wavelength shift during the regrowth was found to be reversible by switching on or off the light illumination. A plausible explanation for such light driven phenomenon could be due to photothermal effects, in which plasmon-induced hot electrons result in Au ions being reduced more easily upon light illumination. These findings suggest a flexible method to control AuNRs synthesis and contribute understanding to plasmon-mediated metal nanoparticle synthesis at the single nanoparticle level.