  We have investigated in detail the growth dynamics of gold nanorods with
various aspect ratios in different surrounding environments. Surprisingly, a
blue shift in the temporal evolution of colloidal gold nanorods in aqueous
medium has been observed during the growth of nanorods by UV visible absorption
spectroscopy. The longitudinal surface plasmon resonance peak evolves as soon
as the nanorods start to grow from spheres, and the system undergoes a blue
shift in the absorption spectra. Although a red-shift is expected as a natural
phenomenon during the growth process of all nanosystems, our blue shift
observation is regarded as a consequence of competition between the parameters
of growth solution and actual growth of nanorods. The growth of nanorods
contributes to the red-shift which is hidden under the dominating contribution
of the growth solution responsible for the observed massive blue shift.
