Surface-enhanced Raman scattering: from the colloid to the stabile substrate

Mikac, Lara (2016) Surface-enhanced Raman scattering: from the colloid to the stabile substrate. Doctoral thesis, Faculty of Science > Department of Chemistry.

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Abstract

The substrates for surface enhanced Raman scattering (SERS) were prepared in three different ways: (i) the synthesis of silver colloidal suspension, (ii) the deposition of silver on the previously electrochemically etched silicon and (iii) vapor deposition of silver on a monolayer of polystyrene microspheres. Colloidal suspensions were synthesized by reduction of silver salts (AgNO3) with various reducing agents. The first type of solid substrates was obtained by the deposition of metal on the porous silicon using immersion plating method, by applying Ag colloidal solution or by pulsed laser ablation. Another type of solid SERS substrates was prepared by deposition of monodisperse polystyrene spheres (350 and 1000 nm) in a monolayer on a hydrophilic glass surface. Different thicknesses of metal films were evaporated on the substrates using e-beam deposition. All prepared substrates were tested for their SERS activity using the test molecules (pyridine, rhodamine 6G, methylene blue). For the colloidal suspension where the size of Ag particles was about 40 nm and with the use of sodium borohydride as aggregating agent the enhancement factor for pyridine of the order of 106 was reached. For the substrates based on porous Si the lowest limits of detection obtained were 10-10 mol L-1 for methylene blue (with 633 nm excitation) and 10-9 mol L-1 for rhodamine 6G (with 514.5 nm excitation). For substrates based on polystyrene spheres best achieved detection limits were 10-9 mol L-1 for rhodamine 6G and 1.2 × 10-3 mol L-1 for pyridine. Synthesized colloidal SERS substrates have been applied for the detection of low concentrations of histamine and aflatoxin B1.

Item Type: Thesis (Doctoral thesis)
Keywords: colloid, nanoparticles, polystirene spheres, porous silicon, substrates, surface enhanced Raman spectroscopy/
Supervisor: Ivanda, Mile
Date: 2016
Number of Pages: 174
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Faculty of Science > Department of Chemistry
Depositing User: Branka Maravic
Date Deposited: 25 Feb 2016 12:01
Last Modified: 25 Feb 2016 12:01
URI: http://digre.pmf.unizg.hr/id/eprint/4517

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