Applet Launcher Applet 1 Applet 2 Applet 3 Applet 4 Applet 5 Applet 6   Rotational Raman Spectroscopy Experimental Techniques page 3 of 3     Practical Navigator Introduction The Raman Effect Experimental Techniques 1. Rotational Raman Spectroscopy Interpreting the Spectrum Effect of Bond Length Centrifugal Distortion Intensities of Spectral Lines Nuclear Spin Statistics 2. Real Diatomic Molecules Temperature Spectrum of Nitrogen Isotopic Substitution Nuclear Spin Statistics Predict the Spectrum of Oxygen   Advantages of Raman Spectroscopy - The laser produces a narrow beam of light; consequently a spectrum can be obtained from very small samples, or from small areas in larger samples, which allows characterisation of different regions of a surface, for example. - Unlike infrared spectroscopy both incident and scattered radiation are typically at ultra-violet or visible frequencies so glass or quartz optics and sample containers can be used; water is often a feasible solvent. In contrast, IR spectra usually require the use of NaCl or KBr plates. Disadvantages - High-powered lasers may lead to decomposition of the sample. - Florescence occurs when an electronically excited molecule decays back to the ground state spontaneously. Such radiation can completely swamp the weak Raman signal. Using a different laser frequency can generally solve this problem.     << previous page www.physchem.ox.ac.uk next page >>