Fourier transform infrared spectroscopy, or FTIR, is a vibrational spectroscopy method which is based upon the measurement of specific frequencies which occur between chemical bonds in a given material. Interestingly, as materials may be unique in chemical nature, so are the infrared spectra which they yield, resulting in a unique “fingerprint” for a given material. As such, this makes FTIR a very resourceful tool for such things as:

• Differentiating between different materials
• Identifying unknown chemicals
• Determining homogeneity/heterogeneity
• Possibly differentiating sub-classes within a chemical family

FTIR is undoubtedly another spectroscopic technique which can stand on its own. Additionally, by combining the advantages of FTIR with an instrument which can perform the technique at a micro level, you know have one powerful instrument capable of mining further into chemical identification.

As previously discussed in a preceding blog, Gateway Analytical utilizes Bruker Optics TENSOR Spectrometer and HYPERION Microscope FTIR systems for our purpose of analytical and R&D-based investigations. This combination of instruments allows Gateway Analytical to measure microscopic samples which would otherwise not be possible on traditional FTIR systems.

Commonly, the types of samples received for identification tend to be very small, on the order of tens to hundreds of micrometers. Because Gateway Analytical utilizes numerous analytical methods (SEM-EDS, Raman, optical microscopy/PLM, etc.) for a thorough and complete chemical identification, a limited amount of representative sample must be prepared for each analysis. By utilizing the micro-FTIR system, we are able to probe further into the chemical makeup of this minute sample and obtain a solid chemical identification.

The following scenarios are just the beginning of a list of examples in which micro-FTIR was used to probe further into chemical identification:

• Paint layers in automotive paints
• Clear coats and associated chemical information on metallic flakes and particulates
• Dyes contained in textile fibers
• Qualitative studies surrounding commercial liquids, extracts and consumable products
• Confirming the presence or absence of trace chemicals in various materials

In conclusion, FTIR is one of the most versatile and powerful spectroscopic techniques for chemical identification. Combining the power of FTIR at a microscopic level only adds to the power of delving into chemical identification at the microscopic level.