Fourier transform-Raman spectroscopic experiments are being introduced into several laboratories for chemistry and biochemistry majors and other upper-level science students. The higher resolution (about 0.1 cm-l) and near-infrared range of the new FT-Raman instrument permit more sophisticated experiments. For the biochemistry laboratory, students use Raman spectroscopy in a new experiment to study synthetic phospholipid bilayers dispersed in water. Students will monitor the change from ordered to disordered structure in the hydrocarbon chains in the interior of dipalmitoylphosphatidylchloine bilayers as a function of temperature by observing intensities in the CH and CC stretching regions. The effect of cholesterol as an additive is studied allowing students learn more about the structure of cell membranes. In the analytical chemistry laboratory students use Raman spectroscopy to study the composition of a standard xylenes mixture using the method of internal standards. They will also compare the ease of sampling for Raman and infrared spectroscopies. For the physical chemistry laboratory, the scope of analyzing vibration-rotation bands by infrared spectroscopy will be extended. As an alternative to the classic experiment of analyzing the rotational structure due to the two chlorine isotopes in HCl in the gas-phase vibration-rotation absorption band, it is now possible for students to do a similar experiment on the bromine isotopes in HBr. The improved near-infrared capability facilitates the study of overtones in the HCl or HBr spectrum and thus mapping the lower part of the potential well and finding how the bond length varies with vibrational excitation. For students in the advanced analytical and physical laboratory, a new experiment comparing the Raman and infrared spectra of the cis and trans isomers of 1,2-dichloroethylene provides data used to assign all twelve of the vibrational fundamentals of each of the isomers. Both the infrared and Raman features of the new instrument support und ergraduate student research. This instrumentation provides opportunities for students to have a broader, deeper understanding of the theory and application of vibrational spectroscopy.
