Eur. Phys. J. Appl. Phys. (2016) 73: 10501
https://doi.org/10.1051/epjap/2015150404

Regular Article

Focus and enlarge the enhancement region of local electric field by overlapping Ag triangular nanoplates^*

The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, 710049 Xi’an, P.R. China

^a e-mail: nanoptzhao@163.com

Received: 1 August 2015
Revised: 4 November 2015
Accepted: 30 November 2015
Published online: 13 January 2016

Abstract

The local electric field enhancements of overlapping Ag triangular nanoplates are investigated using the discrete dipole approximate (DDA) method. The enhancement region of local electric field in the gap could be focused and enlarged by adjusting the thickness and the number of layers of the nanoplates. For the double-layer Ag triangular nanoplates, with the thickness increasing, the electric field enhancements transform from near the corners to the center of the gap gradually and the intensities get stronger. The largest “hot spot volume” appears as the thickness increases to 20 nm. The plasmonic coupling between the two nanoplates leads to the surface charges accumulating on the surfaces adjoining the gap. The variation of the surface charges due to the increase of the thickness should be responsible for this phenomenon. For the multilayer Ag triangular nanoplates, the enhancement region enlarges as the number of layers increases. And the “hot spot volume” could reach about 72% of the total volume of the middle gap when the number of layers is 6. The large volume of the intense electric field enhancements obtained in overlapping Ag triangular nanoplates provide potential for surface-enhanced Raman scattering (SERS) and surface enhancement fluorescence (SEF) applications.