The absence of the shell-related peak, as well as the fact that the optimum annealing temperature (and therefore the Ag film morphology and its plasmon parameters) differs for SERS of Rh6G and semiconductor NPs indicate that the resonant excitation of the plasmon alone is not enough to cause the SERS effect of the semiconductor NPs.
This is well displayed in the extinction spectra (Figure 2) in which the surface plasmon resonance peak is red shift compared to others although they all exhibit broad spectra from visible to near-infrared range due to complex morphology and hybridization of plasmons associated with longitudinal plasmon resonance of rods and multipole resonance.
The autofluorescence channel and plasmon resonance channels were assigned unique color LUTS.
The surface plasmon bands for the gold nanoparticles usually ranges between 510 and 560 nm in aqueous solution depending upon the function of their morphology, since plasmon bands are very sensitive to the length and sharpness of the tips of nanomaterials.
The symmetry properties of the plasmon modes proved powerful in analyzing the interaction between various plasmon modes and also between light and plasmons.
In particular, the properties of plasmons [18, 19] and hybrid plasmon-photon [20] and plasmon-phonon [21, 22] modes were investigated theoretically and experimentally.
Furthermore, the absorption spectrum of nanoparticles could shift depending on color, morphology, and size due to the gold plasmon resonance property [73].
Experiments have demonstrated that the plasmon peak depends strongly on the morphology and assembly of the nanoparticles, such as diameter [18], aspect ratio [35], shape [36, 37], or assembly of array and the lattice parameters of the array [38] and the dielectric constant of the host medium [39, 40, 41].
Au-CHX showed the maxima surface plasmon resonance (SPR) band at 535 nm, spherical morphology and polydispersity with size in the range of 20 100 nm.
Apart from that, exploiting the potentials of plasmons on the surface of metal oxide semiconductors via tuning the nanoparticle size and morphology, and appropriate selection of stabilizing ligands could improve the charge transfer at the plasmon/semiconductor interface.
