Title

The construction and utilization of a Raman spectrometer for the purpose of testing surface-enhancement.

Date of Award

5-1-2014

Document Type

Thesis

School

College of Liberal Arts

Degree Name

Bachelor in Arts

Abstract

Raman scattering is a form of inelastic light scattering in which a photon loses some of its energy in a collision with a molecule. The difference between the wavelength of the incident light and the scattered light reveals the vibrational states of the molecule. As these vibrational states correspond to specific bonds between atoms in a molecule, the Raman spectrum can be used to identify molecules. There are several forms of Raman spectroscopy which attempt to enhance the signal, including surface-enhanced Raman spectroscopy (SERS). Raman spectroscopy is a very useful tool in the analysis of many different materials because samples require very little preparation. This means that Raman spectroscopy can be used in applications in which it is important to analyze a sample nondestructively. However, these applications frequently utilize high cost commercially available spectrometers which may not be accessible to many researchers. In order to overcome this obstacle, Raman spectroscopy systems have been constructed less expensively using an excitation source, various optical elements and a spectrometer. For this honors thesis, I constructed such a system and tested it with two spectrometers which offered varying degrees of ease of use and resolution of data. In order to construct the spectrometer, I used a 633 nm laser as an excitation source. The spectrometer was found to be able to obtain spectra from both solid and liquid samples. In order to test this spectrometer, aspirin, pyridine, benzene and naphthalene were used as samples. The set-up was then tested with a SERS substrate. The substrate was analyzed both with and without pyridine. In both cases, a spectrum was obtained which consisted of two intense peaks not in agreement with the spectra of pyridine. These peaks were investigated and do not match known background signals for these substrates as reported by their manufacturer. The exact nature of these peaks is still unknown.