The Process Behind AFM-IR


AFM-IR is a fascinating process which aims to spot the qualities in varying solid and liquid materials through analysis at a molecular level. Essentially, how exactly AFM-IR works is through radiation being concentrated and focused into a beam, which causes a molecular change in the material in question. As the atoms react to this radiation, they swell, and the expansion is then measured using a cantilever or a probe.

As the cantilever moves with the atom, a machine will record the changes to the smallest nanometre, and then this data will be used in a series of applied mathematics formulas to work out all manner of information about said material, such a properties and so forth. The Industrial Science Blogger has an excellent write-up of the process in the form of their article What is AFM-IR, and we recommend giving it a glance over.

Once you understand the science behind AFM-IR, you might wonder how exactly the process goes. It’s far from a simple one, and the interpretation of spectra is challenging as there are hundreds of known functional groups. Essentially, the usage of an AFM-IR which can provide conditions which have low noise, little or baseline offset, a flat baseline and a lack of spectral artefacts is imperative.

There are a number of AFM-IR manufacturers throughout the world, but Anasys Instruments is generally considered a world leader in AFM-IR technology. Their recent innovation, the Mirage IR microscope, utilises a unique take on AFM-IR, enabling the method to be utilised for even more applications.

Whether you’re using the mirage IR or an older method, there are a number of things which can skew the results of your analysis. Water vapour and carbon dioxide can often interfere with spectra results, as well as other gases where ambient concentrations are high enough to interfere with the results by generating abnormally high peaks.

Readings of the environment before the material is tested can be highly important to working out an offset, in order to prevent misinterpretation as being part of the sample. This is accomplished by taking reference spectra of each of these materials and then comparing them to the sample. As the materials are re-identified, unknown peaks will remain, which should be the result of your material and no other element.  

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