Raman spectroscopy setup and experiments for the advanced undergraduate lab

Abstract

Raman Spectroscopy is an important characterization technique in analytical chemistry and in solid state physics. This contribution describes the redesign of a Raman experiment for the Advanced Physics Lab and shows experimental results acquired with this new setup. Solid and liquid samples are irradiated by a frequency doubled Nd:YAG laser in backscattering geometry. The emission is focused onto the fibre end face of an USB spectrometer. Stokes and Anti-Stokes emission lines are observed simultaneously and their polarisation is analysed. The students start with the spectral calibration of the spectrometer and check its linearity. They optimize their first Raman spectrum of solid sulfur according to these results and evaluate the intensity ratio of the corresponding Stokes and Anti-Stokes lines for a temperature measurement of the sample. The students explain the spectral differences of a series of chlorine-substituted hydrocarbons by the changes in the molecular structures and symmetries. Finally they determine the concentration of an unknown water-ethanol solution. This contribution discusses also safety concerns regarding the used hydrocarbons and shows alternative samples.