FTIR
Definition
Fourier-transform infrared spectroscopy. A Michelson interferometer modulates all wavelengths simultaneously, the interferogram is Fourier-transformed into the conventional absorbance versus wavenumber spectrum.
- Full name
- Fourier-transform infrared spectroscopy
- Interferometer
- Michelson interferometer
- Output
- Absorbance versus wavenumber spectrum
- Common variant
- ATR-FTIR
Common questions
What advantage does the Michelson interferometer give FTIR over older dispersive infrared instruments?+
It modulates all wavelengths simultaneously rather than scanning one wavelength at a time through a slit, which dramatically increases the signal reaching the detector and cuts scan time from minutes to seconds while improving the signal-to-noise ratio, an effect known as the Fellgett advantage.
What kinds of forensic samples is FTIR commonly used to identify?+
It is applied to paints, fibres, polymers, drugs, and inks by matching a sample's absorbance spectrum, which reflects its functional groups and molecular bonds, against reference libraries, and the ATR accessory allows solid or semi-solid samples to be analysed with little to no preparation.
Related terms
- ATR-FTIR
- Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy: a non-destructive mid-infrared method that analyses a single drop of milk pressed against an ATR crystal....
- Fingerprint Region
- The 1500 to 400 cm⁻¹ stretch of an infrared spectrum where bending and combination bands produce a pattern unique to a given...
- Group Frequency
- A characteristic absorption band associated with a specific functional group (carbonyl about 1700 cm-1, hydroxyl 3200 to 3600 cm-1) used to read...
- KBr Pellet
- A classical solid sample mode: 1 to 2 mg analyte ground with about 200 mg dry KBr and pressed in a 13...
- Wavenumber
- The reciprocal of wavelength expressed in cm-1, the universal IR axis. Higher wavenumber means higher photon energy. The mid-IR window is 4000...