Infrared Spectroscopy

Introduction to Infrared Spectroscopy

• Infrared (IR) spectroscopy is a chemical analysis technique used to identify and study chemicals.
• It works by measuring the absorption of infrared radiation by a substance, which results in molecular vibrations.
• Different bonds and different groups of atoms absorb infrared light at different frequencies. Therefore, molecules have unique infrared absorption patterns.

How Infrared Spectroscopy Works

• An IR spectroscope passes infrared radiation through a sample.
• Certain frequencies of the radiation are absorbed by the sample, causing molecular vibrations.
• Other frequencies pass through the sample without being absorbed. These transmitted frequencies are detected by the spectroscope.
• The spectroscope then produces an IR spectrum, which is a graph of infrared absorbance (or transmittance) versus frequency (or wavelength).
• Peaks in the spectrum represent different functional groups in the molecule and thus can be used to identify its structure.

Applications

• IR spectroscopy has many applications in scientific research, environmental testing, and quality control.
• It can be used to identify unknown substances, to determine the quality of a sample, and to monitor reactions by determining which substances are present at the beginning and end.
• It is also used in forensic science for analysis of crime scene evidence, such as paint chips, residues and fibres.