What is FTIR Spectroscopy? – Technology Introduction – METTLER TOLEDO - EN

Fourier Transform Infrared (FTIR) is a type of Infrared (IR) spectroscopy that has been in existence for several decades now as a valuable tool to interrogate samples of unknown composition. FTIR is one of the most heavily used optical spectroscopy techniques by scientists in academia, government, and the industrial sector. Infrared spectroscopy takes advantage of the fact that atom-to-atom bonds vibrate at specific frequencies. When energy, comprised of multiple frequencies (such as that from an infrared source), is introduced to these molecular vibrations, an absorption of that infrared energy occurs at that same molecular vibrational frequency. Plotting the intensity of the absorbance across a range of frequencies yields an infrared spectrum. Furthermore, bonds of different types (e.g., double, triple) and different atoms (e.g, C-O, C-H, C-N, etc.) each have specific vibrational frequencies. The specificity of these vibrational frequencies can be thought of as a fingerprint of the atom-to-atom bonds that make up a given molecule. This fingerprint then makes it possible to identify molecules or compounds in a mixture and likewise can detect the making and breaking of chemical bonds that occur in a reaction.

Since IR spectroscopy follows the Beer-Lambert Law (A=abc), where A is the absorbance of vibration being investigated, (a) is the molar absorptivity (essentially the degree to which a particular vibration absorbs IR energy), (b) the optical pathlength and (c) the concentration or number of the same vibrational frequencies or bonds. Molar absorptivity and path length are generally considered fixed and thus constant, so the result of the Beer-Lambert Law is that the Absorbance of a particular molecular vibration is directly proportional to its concentration (or the number of those molecular vibrations/bonds). This law then makes it possible to calibrate the FTIR instrument for given molecules or compounds of interest such that subsequent measurements of these compounds will be quantitative (absolute). The coupling of FTIR with Attenuated Total Reflectance (ATR) has further expanded the utility of this measurement technique by now allowing for compositional measurements of key compounds in situ. Now real-time measurements of the making and breaking of chemical bonds that take place in a reaction can be obtained in the reaction medium, without perturbation or without the requirement of extractive sampling for offline analysis. In real-time, ATR-FTIR spectroscopy can be used to quickly gain valuable reaction information such as reaction initiation, reactive or transient intermediates, endpoint, kinetics, and mechanistic information.

What is Raman spectroscopy?    • What is Raman Spectroscopy?  
What is the difference between FTIR and Raman?    • What's the Difference Between Raman a...  
What is ATR Spectroscopy?    • What is ATR? (Attenuated Total Reflec...  
FTIR Spectroscopy: https://www.mt.com/us/en/home/applica...
In-Situ FTIR Spectroscopy: https://www.mt.com/us/en/home/applica...
ATR-FTIR Spectroscopy: https://www.mt.com/us/en/home/applica...
FTIR Spectrometers: https://www.mt.com/us/en/home/product...
Raman Spectroscopy: https://www.mt.com/us/en/home/applica...
Raman vs IR Spectroscopy: https://www.mt.com/us/en/home/applica...

0:05 - What is FTIR spectroscopy?
0:19 - How Does FTIR Spectroscopy Work?
1:13 - Coupling FTIR with ATR
1:46 - What Type of Technique is FTIR Spectroscopy?
1:56 - Beer-Lambert Law
2:18 - Quantitative Analysis
2:28 - Real-time quantitative information

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