• Non-aqueous liquids or solids
• Sub-millimeter thickness required

A sample is illuminated with infrared light, the absorption of which causes molecular vibrations in the sample. These vibrations are characteristic of functional groups in the sample. A representative spectrum is shown to the left with some of the evident functional groups denoted. FTIR is not able to determine connectivity of functional groups.

FTIR microscopy is capable of determining the major organic chemical species present in a sample, with a detection limit of 1-5% by weight. It is capable of resolving spectral changes throughout a sample through point, line and global scans at a scale of 6.25 microns or larger.