Fourier Trans­form Infra­red Spectroscopy (FTIR)

FTIR spectroscopy (Fourier transform infrared spectroscopy) is an analytical method used to identify chemical (usually organic) compounds and to investigate their molecular structure. Infrared light is sent through a sample and the absorption of the light is measured based on the excitation of molecular vibrations. Each chemical bond in a molecule absorbs infrared light at specific wavelengths, creating a unique "spectrum" that serves as a fingerprint of the substance.

FTIR microscopy combines FTIR spectroscopy with a microscope to obtain chemical information at the microscopic level. This technique also allows small samples (in the um range) to be analyzed (such as particles or defects in polymers).

Another possibility is chemical imaging. The surface of a sample is sequentially irradiated with infrared light and the absorbed wavelengths are measured. This allows detailed chemical maps to be created that visualize the distribution of different compounds on a sample surface. This is particularly useful in materials science or biology.