Information on the polarization properties of scattered light from plasmonic systems
are of paramount importance due to fundamental interest and potential applications.
However, such studies are severely compromised due to the experimental difficulties
in recording full polarization response of plasmonic nanostructures. Here, we report
on a novel Mueller matrix spectroscopic system capable of acquiring complete
polarization information from single isolated plasmonic nanoparticle/nanostructure.
The outstanding issues pertaining to reliable measurements of full
4 × 4 spectroscopic scattering Mueller matrices
from single nanoparticle/nanostructures are overcome by integrating an efficient
Mueller matrix measurement scheme and a robust eigenvalue calibration method with a
dark-field microscopic spectroscopy arrangement. Feasibility of quantitative
Mueller matrix polarimetry and its potential utility is illustrated on a
simple plasmonic system, that of gold nanorods. The demonstrated ability to record
full polarization information over a broad wavelength range and to quantify the
intrinsic plasmon polarimetry characteristics via Mueller matrix
inverse analysis should lead to a novel route towards quantitative
understanding, analysis/interpretation of a number of intricate plasmonic effects
and may also prove useful towards development of polarization-controlled novel
sensing schemes.
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 nano-systems, 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. Supplementary material for this article is available.
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