In Fourier transform infrared spectroscopy (FTIR), an infrared spectrum of a sample is made by passing a beam of infrared light through a sample or reflecting off of the surface of the sample. The infrared light is absorbed at specific frequencies representing the vibrations of bonds or groups in the molecule. For a vibrational mode in a molecule to be infrared active, it must have a permanent dipole. An absorbance spectrum is produced, showing peaks at the wavelengths that the sample absorbs, revealing details about the molecular structure of a sample.
FTIR spectroscopy is a qualitative technique and is particularly useful in analyzing and identifying organic and some inorganic compounds. Searchable in-house, electronic, and on-line spectral databases are commonly utilized and are invaluable in identifying industrial chemicals and products.
Samples can be as small as 20µm and the FTIR spectrometer is sensitive to components that are present in concentrations greater than approximately 3-5% of the total.
Since FTIR is qualitative, it is typically useful to also analyse samples by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). FTIR, coupled with SEM/EDX, is often used to survey surface analytical problems before proceeding to techniques that are more surface-sensitive and specialized.
Instrument:
Bruker Tensor II system
Hyperion 2000 microscope
System Capabilities:
Selected Applications in Industry: