Silver nanoparticles produced by laser ablation for a study on the effect of SERS with low laser power on N719 dye and R
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.157
Silver nanoparticles produced by laser ablation for a study on the effect of SERS with low laser power on N719 dye and Rhodamine-B Nelson Fabian Villegas Borrero1, José Maria Clemente da Silva Filho1, Viktor A. Ermakov1 and Francisco Chagas Marques1 1
State University of Campinas, IFGW, Campinas, SP, 13083-859, Brazil.
ABSTRACT
The effect of surface-enhanced Raman spectroscopy (SERS) was investigated in N719 dye thin films deposited on silicon wafer with a thin film of silver nanoparticles (Ag-NPs) fabricated by laser ablation in an aqueous solution, using a NdYAG laser (λ = 1064nm). Optical absorption spectroscopy of the Ag-NPs colloidal solution shows an absorption peak at λ = 400nm, associated with a localized surface plasmon resonance in the Ag-NPs. Scanning electron microscopy (SEM) reveals that these NPs have an approximately spherical shape, with their diameter being tunable by laser power intensity. Raman spectroscopy measurements were performed using low laser power to avoid damage to the N719 dye films. Thus, a small Raman signal is obtained. The Raman intensity was greatly increased when the N719 film was deposited on a substrate with a thin film of Ag-NPs due to the SERS effect. The process was also used in Rhodamine-B to clearly demonstrate the SERS effect obtained by the use of these NPs produced by laser ablation.
INTRODUCTION Metal, semiconductor and insulator nanoparticles (NPs) have recently attracted researcher’s attention due to their impressive potential applications [1-12]. This is owing to the ease with which their optical and electronic properties may be tuned, simply by adjusting their size and shape [13-17]. The optical properties related to the scattering and absorption of light are useful in many research fields, such as light absorbers in photovoltaics [18-20], biological sensing and imaging [21], enhanced photo-switchable bactericidal effects [22], chemo-electronic circuits [23] and various physical phenomena such as SERS [24-27] and localization of light [28]. The above applications depend on NPs diameter. For instance, metallic NPs with diameters of 100nm have been used as light scatters, to increase light absorption in solar cell devices [29]. Conversely, in smaller NPs, with diameters of the order of 20nm, other interesting effects arise, such as a strong electric field around the nanoparticle, which is due to the oscillation of free
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electrons, a phenomenon known as localized surface plasmon resonance [30-33]. Metallic NPs have been produced by a number of techniques, such as, chemical reduction using a variety of organic and inorganic agents [34], physic-chemical reduction [35], evaporation and condensation [36], and laser ablation [37]. Today, the most utilized technique fo
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