2018 BFY III Abstract Detail Page

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Abstract Title: W22: Fourier Transform Spectroscopy in the Visible Range
Abstract: Fourier Transform (FT) spectroscopy is commonly used in the infrared (IR) part of the electromagnetic spectrum constituting FTIR spectroscopy. IR spectrometers using diffraction are expensive and cumbersome. For this reason FTIR spectrometers are often used to record vibrational spectra of organic molecules and polymers. During this laboratory we use a homemade FT spectrometer in the visible to demonstrate the mechanism of FT spectroscopy. In addition to demonstrating an important spectroscopic tool, this laboratory exercise deepens the understanding of FT's. It is also an opportunity to practice optical alignment, digital data collection and discrete data processing. A Michelson interferometer is used to determine the `unknown' wavelength of a green laser beam (a HeNe) by scanning the position of a mirror and comparing the number of observed fringes with that from a known-wavelength red HeNe laser beam – the reference beam. The data can be recorded electronically using a photodiode. LabView software maybe convenient if it is available in the laboratory; however, other cost efficient options for data recording exist such as Arduino or a digital oscilloscope (Picoscope). Fourier transform (FT) techniques will be used to analyze the data available in common scientific software packages like MatLab, Mathematica or Origin. Using a discrete FT, the calibration of the reciprocal space leads to the measurement of the unknown laser frequency. The FT will show two peaks: The known peak, which is the red laser line and a peak of unknown frequency, which is the green laser. After using the red line to calibrate the FT spectrum, the exact frequency of the green laser can be determined. This apparatus is great in having student understand how a FTIR (Fourier Transform Infrared) spectrometer functions and what some of the experimental requirements are.
Abstract Type: Workshop
Contributed Paper Record: Contributed Paper Information
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Author/Organizer Information

Primary Contact: Jenny Magnes
Vassar College

Workshop Documents

Workshop Doc 1: Download the Workshop Doc 1