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Spectroscopy – the study of interactions between matter and electromagnetic radiation – has a long history in the physical sciences, beginning with Isaac Newton’s experiments in optics in 1666. Since then, spectroscopy has become the principal tool used by scientists to further the fields of physics, chemistry, and astronomy due to its methods enabling them to investigate matter on the atomic, molecular and macro scales and over astronomical distances.
Overview of Spectroscopic Techniques
Recently, spectroscopy has even enabled the incredibly difficult association of gravitational waves with a spectral signature, and therefore their first detection by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2016, one hundred years after they were proposed in theory by Albert Einstein.
For decades now, spectroscopy methods have also been brought to bear on the collection of research focuses that make up clean technology, primarily in air monitoring (Hanst and Morreal, 1968). Clean technology may be defined as:
“[A] set of technologies that either reduces or optimizes the use of natural resources, whilst at the same time reducing the negative effect that technology has on the planet and its ecosystems.”
At the forefront of clean technology research, is the study of organic photovoltaics. This year, Heidelberg University (Germany) researchers developed a new method of spectroscopy to map energetic landscapes in organic photovoltaic materials (Lami et al., 2019). This data enables the researchers to effectively study the degradation of photovoltaic materials, and therefore develop a means of mitigating degradation.
The most prevalent use of spectroscopy in clean technologies has historically been in environmental sciences. In these interdisciplinary fields, spectroscopy tools are commonly used for analysis – enabling scientists and policy-makers to understand how the environment is affected by various factors.
Researchers at the University of Iowa have recently been using remote spectroscopy to detect volatile organic compounds in the atmosphere (Wabomba, Sulub, and Small, 2007). The team set up a passive multispectral infrared sensor to collect imaging data from an aircraft platform. This imaging data was collected as the aircraft passed over-controlled release experiments at altitudes between 671 m and 853 m, and then analyzed automatically by onboard computers. The experiment also monitored a methanol release from a nearby chemical manufacturing facility.
Application of Spectroscopic Techniques
This is just one example: the majority of atmospheric pollution research uses spectroscopic techniques, due in part to the fact that they can be used to monitor in situ atmospheric conditions without needing to take samples. Another example is the use of open-path Fourier transform infrared (FT-IR) spectrometers in detecting toxic gases released in industrial and manufacturing sites accidentally (Smith, 2019).
The technique used mid-infrared laser diodes, labeled quantum cascade labels (QCLs), in spectrometers composed of the diode, proper reflectors, and detectors. This has resulted in a robust device that researchers used to monitor air quality at the 2008 Beijing Olympics as well as in rural villages around the world (Daukantas, 2015).
Raman spectroscopy is also commonly used for clean technology purposes (Cuffari, 2019). The technique, which is often used to complement IR spectroscopy, uses a source of monochromatic light to interact with molecular vibrations in the sample. The resulting shift in the light’s energy can be used to identify molecules in the specimen.
In clean technology, this technique is frequently used to determine atmospheric levels of lingering particles from aerosols (whose minuscule size makes them undetectable by other methods), and to identify microplastics which have been washed into water supplies from some clothing and hygiene products.
In the near future, the use of spectroscopy to monitor air quality could be combined with advanced artificial intelligence and unmanned drones to automate processes for environmental monitoring globally, ensuring up to date and accurate readings of levels of volatile organic compounds in our atmosphere are relayed to citizens and policy-makers and can drive good policy and behavior decisions.
- AZoCleantech (2019). Analysis in Environmental Science. [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=863.
- Cuffari, B. (2019). The Impact Raman Spectroscopy Can Have on the Environment. [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=873.
- Daukantas, P. (2015). Air-Quality Monitoring in the Mid-Infrared. [online] Available at: https://www.osa-opn.org/home/articles/volume_26/november_2015/features/air-quality_monitoring_in_the_mid-infrared/.
- Hanst, P.L., and Morreal, J.A. (1968). Detection and Measurement of Air Pollutants by Absorptions of Infrared Radiation. Journal of the Air Pollution Control Association, 18(11), pp.754–759.
- Lami, V., Weu, A., Zhang, J., Chen, Y., Fei, Z., Heeney, M. and Friend, R.H. (2019). Visualizing the Vertical Energetic Landscape in Organic Photovoltaics. Joule, 10(1016).
- Pirolini, A. (2015). What is Clean Technology? [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=532.
- Smith, B. (2019). Conducting Air Pollution Research Using Infrared Spectroscopy. [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=849.
- Wabomba, M.J., Sulub, Y. and Small, G.W. (2007). Remote Detection of Volatile Organic Compounds by Passive Multispectral Infrared Imaging Measurements. Applied Spectroscopy, 61(4), pp.349–358.