Browsing by Author "Esmaeilzad, Nasim Seyedpour"

Now showing 1 - 2 of 2

Open Access
SERS-based trace detection by size and shape controlled noble metal particles with high benefit-cost ratio
(Digital Library, 2021-08-01) Demirtaş, Özge; Khan, Ghazanfar Ali; Esmaeilzad, Nasim Seyedpour; Iftikhar, R. M. Faheem; Öztürk, İ. Murat; Demir, Ahmet Kemal; Ahmed, Waqqar; Bek, Alpan
SERS has become a highly preferred method with the effect of advances in instrument technology and potential for application to many areas from medicine to art conservation for the detection of trace-level environmental and biological analytes. However, the effects of substrate variation and the details of the enhancement mechanism still of concern even much progress has been achieved in recent years. Therefore, it is important to control the size and shape of the materials for maximize the enhancement factor and ensure the reproducibility of the substrates by considering SERS uncertainty principle. In this study, we present novel SERS substrate preparation methods that are highly promising in terms of both signal enhancement and reproducibility with high benefit-cost ratio.
Open Access
Shape and deposition angle control of silver film-over-nanosphere SERS substrates
(Institute of Physics Publishing, 2021-10-06) Esmaeilzad, Nasim Seyedpour; Demirtaş, Özge; Demir, Ahmet Kemal; Bek, Alpan
Thin metallic films on dielectric nanospheres are demonstrated to have a high potential for the fabrication of cost-effective SERS substrates. In addition to the morphological advantages that nanospheres offer for attaining a high density of hot spots, possessing shape adjustability by uncomplicated thermal treatment makes them an attractive platform for tuneable SERS substrates. Furthermore, when combined with the oblique angle metal deposition technique, adjustable gaps at a high density and adjustable shape of metal films, such as Ag films, can be achieved on nanospheres. Applying small changes in deposition angle can provide means for fine adjustment of the Raman enhancement factor (EF), resulting in EF up to 108 measured using crystal violet dye molecule as a Raman analyte. This practice paves the way for the fabrication of high EF SERS substrates at a reasonable cost using a monolayer of self-organized nanosphere patterns. An ultra-thin Ag film coated at 5° tilt is shown to be an excellent substitute for a film deposited at 0° with double the thickness. There is a strong agreement between the experimental results and finite-elements-method-based Maxwell simulations exhibiting expected field enhancements up to 109 at a tilt angle of 5°.