Theoretical simulation of nonlinear regulation of wall thickness dependent longitudinal surface plasmon in pentagonal...

In this paper, the longitudinal plasmon mode optical properties and localized electric field distribution of a single pentagonal gold nanotube are investigated for the first time by the discrete dipole approximation. It is found that pentagonal gold nanotube has stronger electric field distribution compared with circular gold nanotubes when the incident wavelength is located at the plasmon resonance peak. Additionally, we observed that the longitudinal plasmon resonance peak can blue shift nonlinearly with increasing wall thickness, but red shifts linearly with the increase of the length of the pentagonal gold nanotube. The localized electric field analysis reveals that the longitudinal plasmon peak of the pentagonal gold nanotube originates from the dipole resonance mode. The local electric field intensity is controlled by the wall thickness and length. Notably, the effect of wall thickness on the longitudinal plasmon resonance and electric field enhancement can be attributed to the change of the plasmon coupling position and intensity. This work has enriched the theoretical research of pentagonal gold nanotubes and provided ideas for the preparation of high sensitivity nanoprobes biosensors.