Spectral analysis with FTIR: tips and tricks
Fourier-transform infrared spectroscopy (FTIR) is a method used to study the vibrational structure of samples, from either an atomic or molecular level. FTIR has the advantage of being able to monitor the structure and properties of a material without the need for calibration, thus it is a versatile technique with advantages in terms of speed, non-destructive testing, safety, and cost. Additionally, FTIR has had huge success in industries such as material, food, and pharmaceutical science, due to its broad absorbance ranges of infrared radiation.
FTIR works by directing infrared radiation from instrument sources such as ribbons, wires, lamps, or globes through the sample, then allowing it to pass through a detector. This signals pass through the sample, creating a ‘fingerprint’ of the structure of the sample due to the infrared radiation having interacted with the vibrational structure of the sample’s molecular bonds. FTIR is capable of identifying organic, inorganic or organometallic compounds, as well as studying the atomic structure of materials on a molecular level.
FTIR’s major strengths come from its ability to analyze material at an atomic level. Analysis of the exact makeup of a material can be made, along with its structural components. As the signal passes through the sample, materials can be separated independently, with their specific identifications made via FTIR’s data analyzation methods. The data deconstruction allows for a greater level of specificity when compared to other techniques, and allows for high level analysis of molecular makeup and structure.
FTIR allows for a range of analysis techniques such as qualitative and quantitative analysis, as well as mapping. FTIR can be used to measure the thickness of thin films, as well as the porosity and particles of compressed materials. Disease diagnostics is also possible with FTIR, as qualitative analysis can be used to identify microorganisms in small samples.
Overall, FTIR is an important technique in a range of industries. With its versatility, safety, cost-efficiency, and data-deconstructing capabilities, FTIR has been a crucial tool in the understanding of materials and disease diagnostics.
Using of FTIR in Gemstone / Minerals Testing: As most gemstones consist of minerals, the use of FTIR is an effective tool for gemstone identification and is often employed when evaluating inclusions and impurities in gemstones.
Through FTIR, gemologists can examine the characteristic absorption peaks of materials in a sample, allowing them to pinpoint precise identification of certain compounds and minerals. This technique is especially useful for distinguishing between various types of gemstones, as each variety of gemstone will have its own distinct chemical composition. As a result, FTIR can be used to quickly and accurately identify minerals and compounds found in a particular sample, including inclusions and impurities. In addition, FTIR can be used to identify the presence of synthetic or treated gemstones, as the treatments used will create unique spectroscopic patterns that can be identified by FTIR.
To obtain an FTIR spectrum, the sample is placed in an infrared beam and the reflected radiation is analyzed. The results of the analysis will be displayed as a graph, with peaks and valleys representing absorption bands of specific components of the sample. By analyzing the vertical axis of the graph (which indicates the absorption intensity of the sample) and the horizontal axis (which indicates the wavenumbers in which the energy is absorbed), gemologists can identify the minerals present in the sample, reaching a conclusion about the nature of the gemstone.
Although FTIR has been used in gemstone identification for some time, more recently, gemologists have begun to use portable FTIR spectrometers to facilitate identification in the field. This has enabled gemologists to quickly and accurately identify compounds in gemstones while they are still in the ground. Additionally, FTIR can be used in tandem with other analytical techniques, such as X-ray diffraction, to further refine and validate the composition of a sample.
Overall, FTIR is a powerful and reliable tool for gemstone identification and can be used to accurately and quickly identify both unaltered and treated gemstones. It is very useful for both distinguishing between various types of gemstone as well as identifying inclusions and impurities in a sample. By utilizing this powerful analytical technique, gemologists can confirm the identity of gems more quickly and confidently.
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