New coupling mechanism of titanium nitride nanosphere dimers at short separation distances

Abstract

The coupled localized plasmon modes generated by a metal plasmonic nanoparticle (NP) dimer induces a stronger plasmon enhanced electromagnetic field as well as a stronger optical response compared to that of a single NP. Owing to the small Drude damping factor, however, the absorption bandwidth of noble metallic NPs is insufficiently broad. Herein, the near-field wide band coupling absorption for 25 nm diameter TiN nanospheres is investigated in a homo-dimer arrangement for various separation distances using the finite element method. An enhancement of the wide band coupling absorption and a red-shift is found, which can be explained by an uncomplicated dipole-dipole coupling model at interparticle distances greater than 5 nm. At short separation distances, the coupling absorption of the TiN dimer exhibits a tremendous change, which is diametrically opposite the results found for a Au dimer. This unexpected change phenomenon is shown by calculation and analysis to be owing to the change of the charge distribution approach at short separation distances, which is demonstrated to play a key role in the wide band coupling characteristic variation. With decreasing separation gap, a new coupling mechanism caused by surface charge properties is responsible for the decline in coupling absorption as well as the break in the ruler equations for both plasmon shift and temperature enhancement.

New hybridization coupling mechanism and enhanced sensitivity in a Cu2−xS@Au nanoparticle dimer

“…Using the data analysis function of the Origin software can be deconvolved into the corresponding lorentz curve. Therefore, using the Lorentzian curve deconvolution method [8,44], the plasmonic modes of the Cu 2−x S@Au dimer were calculated from absorption spectra for gap = 2 nm, t = 2, 5, 10 nm, and t = 5 nm, gap = 2, 3, 15 nm, as shown in figures 5 and 6, respectively. Each peak deconvoluted from the curve in this way signifies a corresponding plasmonic mode, and three peaks (Peaks 1, 2, 3) were identified in figures 5 and 6.…”

“…The radius (r = t + r 1 ) satisfies the requirements of the Rayleigh approximation, where t and r 1 represent the shell thickness and core radius, respectively, and gap represents the interparticle edge-to-edge separation distance. It has recently been reported that the coupling behavior of NPs is closely related to the polarization direction of the incident light [8,[31][32][33]. Thus, herein, we only calculate the absorption spectra for the parallel polarization direction by the Finite Element Method (FEM) in COMSOL Multiphysics software 5.2 a (installed on a Quad Intel Xeon CPU, 256 GB RAM workstation), with which the absorption is most sensitive to different separation gaps (figure 1(b)).…”

“…Localized surface plasmon resonance (LSPR) peaks exhibit excellent spectral shift behavior with changes in the nanoparticle structure and refractive index (RI) of the surrounding medium, which has motivated diverse applications such as surface enhanced spectroscopy [1,2], chemical sensing and biosensing [3][4][5][6]. Most previous research studies have focused on the effect of the gap distance of a nanoparticles dimer on plasmon coupling [7][8][9]. In particular, the interaction between nanoparticles leads to a strong shift in the resonance frequencies, providing a highly sensitive particle sensing scheme.…”

Review on Stability, Thermophysical Properties, and Solar Harvesting Applications of Titanium Nitride-Based Nanofluids: Current Status and Outlook

“…Among plasmonic ceramics, carbides and nitrides have larger damping factors in comparison to Au NPs. This makes them suitable candidates for application as NPs aiming to attain broadband absorption …”

“…This makes them suitable candidates for application as NPs aiming to attain broadband absorption. 56 Additionally, these NPs hold considerable potential for applications in the field of biology due to their biocompatibility, as evidenced by their localized surface plasmon resonance (LSPR) falling within the biological transparency range of 700 to 1000 nm. Moreover, their substantial absorption cross-section at the plasmon resonance makes them promising for utilization in plasmonic heating applications.…”