What Is FTIR?

Spectroscopy refers to a branch of science that promotes the absorption of light (visible radiation) by organic and inorganic compounds to generate an absorption spectrum. Infrared Radiation (IR) Analysis is a spectroscopy method, specific to IR chemical reactions. Fourier Transform Infrared Radiation (FTIR) is a type of spectroscopy IR analysis that uses infrared radiation to record molecule movements via computer-based programs. It uses a formula called Fournier Transform and a scheme of conversion called Michelson Interferometer.

History

• The first IR instruments can analyze spectra of compounds within the limited range of 600 to 4000 wavelength; however, many organic compounds produce wavelengths higher than this range. Furthermore, the traditional way of analysis can detect solid substances only because water is normally absorbed when using traditional IR analysis. The advent of computer-based procedures and FTIR made this possible through an exceptionally fast process. It can analyze many solutions simultaneously, thus it is applicable to multiple assays. It can detect minute traces of a substance, so it can measure substances with very weak concentration, and it could measure solutions containing water molecules.

FTIR Analysis

• FTIR is the most recent technology that uses IR in quantitative analysis. It is used by organic chemists to determine the components of organic compounds. Most of the organic compounds reveal their distinguishing component when exposed to infrared radiation. The revealed distinguishing component emits energy (wavelength) that is represented by a graph called spectrum.

Advantages of FTIR

• The data collected from FTIR spectrometers are stored in digitized form in a computer that makes it easy to access any time. Another benefit from this technique is the capability to add or subtract spectrum from the solution that makes it very easy to get the individual spectrum of every component. Furthermore, FTIR spectrometers are fast, easy to use and provide accurate results compared to other types of spectrometers.

Features

• Fourier Transform is a mathematical equation that converts the spectral signal performed by a computer from a time domain towards a frequency domain. Its mechanism of action is based on the Michelson Interferometer modulation.

  Time domain is a spectroscopic method that uses high power variation and there is no optical transducer available that could tolerate such high power frequencies.

  Michelson interferometer modulates the high frequencies of time domain to produce low and measurable ones.

Significance

• FTIR can analyze many substances simultaneously, thus it is applicable to multiple assays (tests). It can detect minute traces of a substance. Traditional/Normal analysis can detect substances with high concentration only. FTIR can measure solutions containing water molecules. Water is normally absorbed when using traditional IR analysis.

Spectrum Recording

• Spectrum is the graph that shows movement of compounds when they undergo a reaction involving infrared radiation. The movement of compound is actually a vibration, which results to the emission of energy measured in wavelength or wavenumbers. Thus, the absorption spectrum is a plot of wavelength vs. a beam of radiation.

FTIR Principle

• To identify a component of certain compounds, they are exposed to high energy such as Infrared Radiation (IR). The reaction results to emission of energy showing the reactions of the molecules, which are automatically plotted to a graph by one of the programs embedded in spectroscopic instruments. Using the generated graph, organic chemists analyze the plot and detect distinctive peaks that can be attributed to the components of the compound.

  For instance, a graph shows two distinctive peaks, and after analyzing the plot, you found out that one peak corresponds to Hydrogen (H) and the other is Oxygen (O2); thus, you can safely say that it is H20 or water molecule. Molecules that react with IR always exhibit the same distinguishing peak of energy so they can easily be identified from the graph.