Abstract:
Single molecule detection and characterization is essential in several realms of science
and technology to understand fundamental aspects of molecular dynamics. Surfaceenhanced
Raman scattering (SERS) has emerged as a unique and powerful technique
with single molecule sensitivity and chemical specificity. The heart of this technique
relies on the enhanced electromagnetic (EM) field from localized surface plasmon polariton
(L-SPP), coupled oscillation of light and free electron at the surface of a metal
nanostructure. Thus modulating the SPP towards maximum field intensity is the most
important aspect to harness single molecule surface-enhanced Raman scattering (SMSERS).
Also, to make this technique adaptable in various applications, the study of
SMSERS involving various nanostructures in suitable microscopy system is an imperative
prerequisite. The conventional fluid phase SMSERS experiments are commonly
performed by using chemically aggregated Ag colloidal nanoparticles in focused field
microscopy. Herein we investigate the two aspects of plasmofluidic (i.e. plasmonic
field in fluidic environment) single-molecule SERS, (i) introducing new type of nanostructures
to SMSERS and (ii) employing evanescent-wave microscopy for SMSERS.
We further explore the plasmofluidic field to equip for patterned assembly of nanostructures.
First, we shall discuss on the single-molecule SERS sensitivity of Ag@Au bimetallic
nanostructures in fluid phase with conventional focused field microscopy technique.
We also refer these nanostructures to befit ultra-sensitive trace analysis.
Secondly, we shall dwell on how to harness evanescent-wave excitation to create
electromagnetic hot-spots by assembling colloidal nanoparticles without any chemical
means and to detect single molecule SERS signals with Ag@Au nanoparticles.
Lastly, we shall present that how the extension of above said technique can lead to a
preamble of reconfigurable dynamic lithography of plasmonic nanostructures at metal
fluid interface.
