Two Techniques for High Sensitivity
Surface Infrared Spectroscopy
Grazing angle Fourier-transform infrared external reflection spectroscopy
is sensitive enough to produce a quality spectrum of less than a
monolayer on a surface. The IR beam is reflected off of a sample before
going to the detector. (Picture adapted from a diagram originally
drawn by Dr. Laurel Knott.)
When using materials that are transparent to IR radiation, Brewster-angle
transmissionFourier-transform infrared spectroscopy is a sensitive method
for investigating adsorbates. Using the Brewster angle prevents multiple
internal reflections and, hence, interference patterns.