Developing Tools for Undergraduate Spectroscopy: An Inexpensive Visible Light Spectrometer

The design and implementation of an inexpensive, high-resolution Littrow-type visible light spectrometer is presented. The instrument is built from low-cost materials and interfaced with the program RSpec for real-time spectral analysis, making it useful for classroom and laboratory exercises. Using a diffraction grating ruled at 1200 lines/mm and blazed in the first order, the spectrometer was found to have a resolution (R = λ/Δλ) of 7500 (0.07 nm) at 525 nm allowing for detailed spectroscopic experiments such as an analysis of the iodine vibronic spectrum or multiplet line splitting in the solar spectrum. The simple design of the spectrometer makes it possible to exchange gratings of different lines/mm easily. The instrument provides a means of incorporating macroscopic experimental observations of visible spectroscopy into the undergraduate chemistry program in a practical hands-on way while avoiding the “black-box” nature of many modern spectrometers. Special attention is given to the possibilities such an instrument presents for the introductory chemistry curriculum and example demonstrations and experiments are provided.