Do you know that FT-IR (Fourier Transform Infrared) is an infrared spectroscopic technique that uses an interferometer for data collection and a digital Fourier transformation to process the data?
Are you aware that if someone refers to ‘background’ when they are using the FT-IR technique, it entails the characteristics of the environment of the spectrometer, including the detector and atmospheric conditions? The background spectrum is the result of the output of the source, the response of the beamsplitter optics, sampling module or sample holder, and detector and any atmospheric absorptions inside the analyzer. Sample spectra are ratioed against a background spectrum so that the final spectrum is free of those features.
Do you know the differences between Absorption, Absorbance Spectrum, Absorption Image, Absorption Spectrum, and Absorptivity? Here are some definitions:
Absorption: The transfer of energy from an infrared beam to the molecules present in the path of the radiation.
Absorbance Spectrum: Absorbance is related to Transmittance as follows: A = log 1/T where A is absorbance and T is transmittance. Transmittance spectra are calculated by ratioing a sample single beam spectrum to a background spectrum. Absorbance is linearly proportional to concentration (see Beer’s Law), and should be used for quantitative analysis.
Absorption Image: An image wherein contrast results from differences in radiant energy absorption. A drop of dye in water is an example of an absorption image.
Absorption Spectrum: A spectrum that shows how the absorptivity of a sample varies with frequency or wavelength.
Absorptivity: The value represented by the letter a in the formula of Beer’s Law: A(n) = a(n)bc where A(n) is the absorbance at wavenumber n, a(n) is the absorptivity at wavenumber n, b is the pathlength, and c is the concentration. Also known as absorptive power or molar absorptivity.
What do you call a photographic or electronic recording of an optical interference pattern? And is it related to that device that splits and then recombines a beam of radiation? (Answers: Interferogram and Interferometer)
Is a Cassegrain Lens something you find on your camera or put in your eye, or is it a reflecting element optical system that uses two spherical mirrors (a primary concave mirror and a secondary convex mirror) to focus light energy?
All these tidbits of information and more are contained in our handy FT-IR glossary.
FTIR spectroscopy offers a vast array of analytical opportunities in academic, analytical, QA/QC and forensic labs. Deeply ingrained in everything from simple compound identification to process and regulatory monitoring, FTIR covers a wide range of chemical applications, especially for polymers and organic compounds.
This glossary contains approximately 150 words and phrases that are common to FTIR work.
Download it now to use as a quick reference sheet when you are in the lab or reporting your testing and analysis results.