Understanding blue shift of the longitudinal surface plasmon resonance during growth of gold nanorods

TL;DR

This paper investigates the unexpected blue shift in the surface plasmon resonance of growing gold nanorods, revealing that the shift results from a competition between growth dynamics and the surrounding solution effects.

Contribution

It provides a detailed analysis of the blue shift phenomenon during gold nanorod growth, highlighting the interplay between growth parameters and environmental factors.

Findings

Blue shift occurs during nanorod growth, contrary to typical red shift expectations.

Growth solution effects dominate over nanorod growth in spectral shifts.

The blue shift is due to competition between growth dynamics and solution environment.

Abstract

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.