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Localized Plasmon in Silver Nanoparticles Synthesized by Microwave Radiation



Author(s)

Juan Sebastian Peláez Garzón, Ricardo E. Baez Cruz and Carlos Vargas Hernandez

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DOI:10.17265/2161-6213/2017.3-4.005

Laboratorio de Propiedades Ópticas de Materiales (POM), Universidad Nacional de Colombia, Sede Manizales 170-003, Caldas-Colombia

This work presented the silver (Ag) nanoparticles (NPs) synthesis, by the technique assisted by radiation in the microwave spectrum, each sample was prepared as an aqueous solution based on AgNO₃ at 1 mmol. This mixture was homogenized in polyethylene glycol keeping a proportion of 1:10. A new variable that we called stabilization time was introduced. Every sample was submitted to microwave radiation varying the stabilization time. The exposure time of 60 s and the power of the radiation in 1200 w were maintained. The morphology was characterized using SEM (scanning electron microscopy), where we find sizes of a spheres clusters around 70-170 nm, suggesting the particle size between 20, 30 and 40 nm. The optical characterization of the silver NPs was based on the UV-VIS spectrophotometry. An LPR (localized plasmonic resonance) of wavelength in 320 nm for 3 samples was found, 318 nm for other 2 samples and in 324 nm for the last sample. A Plasmon shift was located due to the variation of the stabilization time. Besides that, we have changed the FWHM (full width at half max) the Plasmon as we modified, indicating a size variation and distribution of the same, according to the data found by electronic micrograph. The intensity of the LPR has moved with the change of the stabilization time, suggesting a higher resonance of the free electrons near the border of the NPs. The pH of every sample was measured with optical methods that are non-invasive, finding that the pH of two samples went off of the measuring range that the instrument has. For those we had to use an invasive method, the values obtained for the pH were in the basic range with values between 6 and 8.

Microwave, plasmon, stabilization, resonance.