Creating Orientation-Independent Built-In Hot Spots in Gold Nanoframe with Multi-Breakages
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In this study, the plasmonic extinction spectra and local field distributions of three different gold nanoframe models with multi-breakages are simulated based on the discrete dipole approximation (DDA) method. By tuning the length of one breakage, there are two clearly separated surface plasmon resonance (SPR) peaks which show a clear blue shift as the broken length increases, and the local field enhancement factor reaches a maximum of 140.8 when the broken length is 2 nm. The changing of plasmonic field interaction and the increased restoring force may be used to explain the resonance blue shift. In these three models, the three-dimensional (3D) local electric field distributions confirm that the hot spot regions mainly concentrate on the interior broken surfaces when the incident electric field is polarized along the broken edge. Moreover, the gold nanoframe with three breakages can create the polarization orientation-independent built-in hot spots inside the broken surfaces. Therefore, the local field enhancement and hot spot regions may be controlled by adjusting the number of breakages and the orientation of polarized field. Consequently, these simulated results about the plasmonic optical properties in gold nanoframe provide a theoretical guidance for the design of polarization orientation-independent SERS substrate, which could create the built-in hot spots and improve the SERS activity.
KeywordsGold nanoframe Multi-breakages Polarization direction Hot spots
This work was supported by the National Natural Science Foundation of China under grant no. 11774283.
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