Authors: N.R. Tiwari, S.A. Kalele, S.K. Kulkarni
Affilation: University of Pune, India
Pages: 246 - 249
Keywords: gold nanorods, pH, blue shift, shape transformation
Metal nanoparticles offer a wide area of application owing to their size and shape dependent optical properties. Recently, there has been significant interest in gold nanorods due to their potential application in the field of biomedical imaging, photo thermal therapy and optoelectronics. Owing to their interesting properties, potential of gold nanorods has also been realized in the field of nanoelectronics and nanophotonics. Gold nanorods of different aspect ratios have been synthesized by various techniques with considerable success. Aspect ratio of gold nanorods is found to be extremely sensitive to nucleation conditions which are further dependent on large number of experimental parameters involved in the seed mediated synthesis. We have synthesized gold nanorods in aqueous solution by seed mediated growth method and studied the dependence of longitudinal plasmon band on various experimental parameters like temperature, pH, amount of seed, ageing of seed, molarity of surfactant and other experimental conditions. Apart from these, we observe a strong modulation of optical properties of gold nanorods on addition of KOH in different amounts. Significant blue shift in the absorption spectra was observed with an increase in the amount of KOH, with the effect being maximum for the longest rod. We attribute the blue shift in the absorption spectra on addition of KOH to the pH dependent shape transformation of gold nanorods. Subsequent changes in the plasmon band have been monitored by uv-vis spectrometer and aspect ratio of gold nanorods has been determined using TEM.