Modification of metal nanoparticles via femtosecond laser pulses and their application for SERSWednesday (24.06.2020) 13:37 - 13:40 Room 1
Metal nanoparticles are attracting a lot of attention recently due to their size and shape dependant optical properties. The resonant collective free electron oscillations in the confined space results in the so-called localized surface plasmons having sharp resonances in the optical spectra . Historically metal nanoparticles were primarily synthesized chemically but with the advent of ultra-short pulse lasers new pathways of synthesis and post processing of the nanoparticles have emerged . Chemical synthesis routes are well elaborated nowadays and one can control size, shape and internal structure in a wide range and volumes of synthesized colloidal solutions may be suitable for industrial applications . Another path to change the morphology, size and shape of chemically pre-synthesized nanoparticles is by irradiation of colloidal solution with ultrashort laser pulses.
In the current research we have synthesized silver nanoparticles via polyol synthesis route . The stock solutions were irradiated with a fundamental harmonic (λ=1030 nm) of a Yb:KGW femtosecond laser (Pharos, Light Conversion). The dependences of the resulting nanoparticles’ optical properties and size distributions on the laser processing conditions, namely pulse energy, keeping constant irradiation time of 30 minutes, were investigated. Surface enhancement of the Raman scattering (SERS) was investigated with 2-naphthalene thiol (2NT) of 10-6M concentration and laser processing conditions ensuring the highest signals were identified.
The absorption of colloidal solutions changed drastically after the irradiation as shown in Fig. 1 a. The surface plasmon resonance peak became narrower and blue shifted indicating the reduction of the average particle size and increased monodispersity (Fig. 1, a). The electron microscopy of the nanoparticles (Fig. 1 b, c) indicated fracturing and rounding of the nanoparticles.
From the Raman scattering spectra (Fig. 1, d) it was obtained that modified nanoparticles demonstrated higher enhancement than the synthesised ones and the enhancement itself depends on the laser treatment. The highest enhancement was obtained for nanoparticles that were modified with 80 mW laser power.
|Category||Short file description||File description||File Size|
|Poster||Abstract||Abstract for the conference section L04-Nanotechnology||242 KB||Download|
|Poster||Poster presentation||Poster presentation (A0)||4 MB||Download|