  A hot-spot of high local field can be created in between two closely placed
metal nanoparticles by irradiating them with an appropriate wavelength and
polarization of incident light. The strength of the field at the hot-spot is
expected to get enhanced by even up to six orders of magnitude than that of the
applied field. Placing a semiconductor quantum dot or an analyte molecule at
the hot-spot is an essential step towards harnessing the enhanced field for
applications. In this article, we show that it is possible to position a CdTe
quantum dot (QD) between two larger silver nanospheres in colloidal solution.
The extinction spectra measured during growth suggests that the final hybrid
nanostructure have two touching Ag nanoparticles (NPs) and a CdTe QD in between
them close to the point of contact. Using ultrafast transient measurements, it
has been shown that the presence of CdTe QD strongly influence the dynamics
when the probe excites the hot-spot. The method demonstrated here to place the
semiconductor QD in between the two Ag NPs is an important step in the area of
colloidal self-assembly and for application of hot-spot in plasmonic sensing,
optoelectronics, energy-harvesting, nanolithography, and optical nano-antennas.
