Abstract
In this study, metallic nanoislands were prepared by thermal annealing of gold thin film produced by vacuum evaporation on a glass substrate to investigate the surface-enhanced Raman scattering (SERS) effect on them. The influence of the analyte on the enhancement factor of SERS was studied with riboflavin and rhodamine 6G dye. Two laser excitation sources at 532 and 633 nm wavelengths were used for SERS measurements. We found that the enhancement factors of the gold nanoisland SERS substrates were influenced by the analytes’ adsorption tendency onto their surfaces. The SERS amplification was also found to be dependent on the electronic structure of the molecules; higher enhancement factors were obtained for rhodamine 6G with 532 nm excitation, while for riboflavin the 633 nm source performed better.
Highlights
Raman spectroscopy is a branch of vibrational spectroscopy that allows highly sensitive structural identification of various chemical and biological materials based on their unique vibrational characteristics, all without destroying the sample
The spectra were recorded with 633 nm excitation, as in the case of riboflavin, a higher Surface-enhanced Raman scattering (SERS) enhancement was obtained with this excitation wavelength
SERS enhancement of gold nanoisland SERS substrates was investigated with two different analytes and two excitation wavelengths (532 and nm)
Summary
Raman spectroscopy is a branch of vibrational spectroscopy that allows highly sensitive structural identification of various chemical and biological materials based on their unique vibrational characteristics, all without destroying the sample. Surface-enhanced Raman scattering (SERS) is a commonly used technique to enhance the signal, that allows the analysis of low-concentration samples or even the detection of a single molecule. The SERS effect can occur when the analyte is in close vicinity of a nanoscale-structured metal surface. By using metal surfaces with optimal parameters, the intensity of Raman signals can be enhanced by several orders of magnitude [2,3,4]. It is accepted that two types of mechanisms play a role in an increase in the intensity of Raman signals: the electromagnetic (EM) enhancement [5] derived from electromagnetic fields generated by plasmon excitation of metal particles serving as SERS substrates, and the chemical amplification [6,7], which allows the target molecule to transfer electrons to the metal particles, often leading to the formation of a chemical bond between the metallic surface and the molecule [2]
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