Difference between FTIR and Absorbance Spectroscopy

“FTIR” and “absorbance spectroscopy” are terms that can be related, and the main difference lies in the specific technique and method of data collection.

  1. Absorbance Spectroscopy:
    • General Term: Absorbance spectroscopy is a broad term that encompasses various techniques where the absorption of electromagnetic radiation is measured.
    • Principle: In absorbance spectroscopy, the amount of light absorbed by a sample at different wavelengths is measured. This can include UV-Vis absorbance spectroscopy, where the absorption of ultraviolet or visible light is measured, or IR absorbance spectroscopy, where the absorption of infrared light is studied.
  2. FTIR (Fourier-Transform Infrared) Spectroscopy:
    • Specific Technique: FTIR spectroscopy is a specific method within the broader category of absorbance spectroscopy.
    • Principle: FTIR measures the absorption of infrared radiation by a sample. It involves the use of an interferometer and Fourier transformation to obtain the infrared spectrum, which represents the absorbance or transmittance of the sample at different infrared frequencies.
    • Advantages: FTIR is known for its high sensitivity, speed, and ability to provide detailed information about the vibrational modes of molecules.

Key Differences:

  • Scope: Absorbance spectroscopy is a general term that includes various methods of measuring absorption, while FTIR spectroscopy specifically focuses on the absorption of infrared radiation.
  • Instrumentation: Traditional absorbance spectroscopy methods may use different types of instruments depending on the region of the electromagnetic spectrum being studied (UV-Vis spectrophotometer, IR spectrophotometer, etc.). FTIR, as a specific technique, uses an interferometer and Fourier transformation for data collection.
  • Data Collection: Absorbance spectroscopy can involve scanning through individual wavelengths, while FTIR spectroscopy collects interferograms over a range of frequencies and then transforms them to obtain a spectrum.

Absorbance spectroscopy is a broad term referring to techniques that measure the absorption of electromagnetic radiation, including UV-Vis and IR methods. FTIR spectroscopy is a specific type of absorbance spectroscopy that focuses on the absorption of infrared radiation, using a Fourier-transform approach for data collection and analysis.

Find out more at our Fourier Transform Infrared Spectroscopy Analysis Laboratory