Applet Launcher Applet 1 Applet 2 Applet 3 Applet 4 Applet 5 Applet 6   Rotational Raman Spectroscopy Experimental Techniques page 2 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   The Laser The rotational Raman spectrum is inherently weak, so high intensity light and sensitive detectors are required. Lasers produce a narrow, highly monochromatic, coherent beam which can be focused very finely onto a small sample. Continuous lasers routinely have powers of up to several watts. but with good detectors, Raman spectra can be observed even using He/Ne lasers. Rare gas lasers (based on Ar+ or Kr+, for example) which are often used in Raman experiments, can produce light a million times more intense than sunlight. Microscope Objective This focuses incoming laser light onto the sample and collects the scattered light. This outgoing light includes both Rayleigh and Raman scattered light. Detector At the spectrometer incoming radiation is dispersed with a grating, and then detected using diodes, a camera or another type of detector. Detectors may be cooled in liquid nitrogen to reduce thermal noise.     << previous page www.physchem.ox.ac.uk next page >>