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Infra-Red Spectroscopy (IR, Near, Mid, Fourier Transform, N-IR, M-IR, FT-IR)

Infrared spectroscopy (IR spectroscopy) is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy.

cogsHow does it work?

The infrared portion of the electromagnetic spectrum is usually divided into three regions; the near-, mid- and far- infrared, named for their relation to the visible spectrum.

The higher energy near-IR, approximately 14000–4000 cm−1(0.8–2.5 μm wavelength) can excite overtone or harmonic vibrations. The mid-infrared, approximately 4000–400 cm−1(2.5–25 μm) may be used to study the fundamental vibrations and associated rotational-vibrational structure. The far-infrared, approximately 400–10 cm−1 (25–1000 μm), lying adjacent to the microwave region, has low energy and may be used for rotational spectroscopy. The names and classifications of these sub-regions are conventions, and are only loosely based on the relative molecular or electromagnetic properties.

Infrared spectroscopy is a simple and reliable technique widely used in both organic and inorganic chemistry (Pharmaceutical, Food Science, Agricultural, Pulp and Paper, Paint and Environmental applications).


Identification of functional group and structure elucidation; reaction progress monitoring; quality control; remote monitoring applications such as the long-term unattended measurement of CO2 and H2O concentrations; forensic analysis – bloodstain age; non-invasive measurement of oxygen and haemoglobin concentrations; polymer degradation monitoring; oil and grease type identification; water content measurement.

Sample Handling Requirements:

Solid or liquid – with solid – generation of thin solid film through generation of acetone or methylene chloride suspension then evaporation onto glass plate (IR Plate).

Complementary Techniques:


Warwick Capability:

No capabilities - reference entry only


Dr Ian Hancox, 024 76 150380 email i dot hancox at warwick dot ac dot uk.

FT-IR equipmentN-IR equipment

Typical results format, and sample:



Warwick collect/analyse data

Warwick collect data
Available to user with expertise/ contribution
Spare capacity for collaborative research
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