Vahideh Rezaie Kahkhaie, Mohammad Hassan Yousefi, Seyyed Mohammad Reza Darbany, Abolhassan Mobashery,
Volume 13, Issue 2 (12-2019)
Abstract
stabilized Ag Nanoparticles (NPs) were synthesized using Lee-Meisel method under three different conditions in an oil bath. UV-Vis spectroscopy of the Ag NPs showed a Localized Surface Plasmon (LSP) band around 430 nm, indicating Ag NPs had a size range around 40 nm. To fabricate a surface Enhanced Raman Spectroscopy (SERS) substrate, LSP properties of Ag NPs was employed with the goal of detecting Rhodamine 6G dye. SERS spectrum was recorded by using 180 degrees, back-scatter Raman configuration in a custom-made mount. The results showed that ideal Ag NPs agglomeration condition had been achieved by applying centrifuging process and due to this, adding NaCl salt to the SERS substrate was found to be unnecessary. The optimum rate of tri-sodium citrate versus silver nitrate and its influence on UV-Vis and SERS spectra was determined. It was understood that in order to obtain a uniform SERS intensity profile, employing a heater-stirrer instead of an oil bath alongside controlling the atmospheric condition and also drying the substrate in the Argon gas medium are the most necessary conditions for Ag NPs synthesize. The novelty point is obtained when SERS of R6G on a certain substrate, immediately after fabrication and after one month, were compared with a bare R6G dye substrate which, have revealed exceptional performance.
Akram Kabiri, Abbas Azarian,
Volume 15, Issue 1 (1-2021)
Abstract
Plasmonic nanosensors have emerged as a powerful tool for biosensing and other applications. Therefore, efforts are underway to achieve higher sensitivity for these nanosensors. In line with this goal, we have investigated the sensitivity of silver square and triangular chiral nanosensors based on two strategies, Localized Surface Plasmon Resonance (LSPR)-based and Circular Dichroism (CD)-based sensing. Chiral nanostructure parameters (height, diameter) and the angle of incidence light have been optimized with calculation method (3-D finite-difference time-domain (3-D- FDTD)) in order to obtain best localized surface plasmon resonance and consequently the highest sensitivity. The calculation results show that sensitivitys~1727 and 1658nmRIU-1 can be achieved in LSPR- and CD-based sensing method respectively for square chiral nanostructure, which are significantly more than previous works.