This article describes a recently introduced, rapid, laser-based hyperspectral method for thin-film analysis in the mid-IR fingerprint range.
With a significant proportion of our regular readership probably under home lock-down, we were wondering if we could help you at this difficult time by pointing out some useful online resources. So, when we finally come out of this pandemic, you could do so better skilled and more up-to-date than when we went in to it.
Tony and Lutgarde Buydens give us an update on the planning for the major EuroAnalysis 2021 conference, which is being held in Nijmegen, the Netherlands, at the end of August 2021. At this stage, they are keen to gather suggestions from readers on topics they would like to see covered. Groups are also invited to consider hosting their own event under the EuroAnalysis 2021 banner.
An interesting insight into, well, a week in the life of the author as a fourth-year PhD student. Katie is working on investigating a way of detecting liver damage using spectroscopy, which is “about as interdisciplinary as you can get”! I’m sure all readers will find it interesting and it may be helpful for those you know who may be considering a PhD.
The authors look at two important areas of recycling of waste materials: concrete and plastics. If aggregates are to be recycled from concrete, the presence of pollutants (plastics, foams, brick etc.) and the degree of removal of cement mortar from the aggregates must be assessed and monitored. NIR hyperspectral imaging with PLS does a good job of both tasks.
Coral reefs have been used as examples of climate change in action for decades, since the “bleaching” caused by corals stressed by heat expelling their symbiotic photosynthesising algae is such a dramatic effect. Jonathan Teague, Jack Willans, Michael Allen, Thomas Scott and John Day describe their work in developing a hyperspectral imaging system that can be deployed on a submersible remotely operated vehicle to monitor coral health through changes in their natural fluorescence
Tony Davies continues his quest to find out what you all need to work more efficiently. You will remember that in the last issue, Tony introduced his survey to discover what developments were needed in spectroscopy by readers. Some of the initial responses are explored, and Tony finds that he has opened a “can of worms”.
We all know how spectroscopy and other analytical technologies have played important roles in detecting fraud and in authentication. Paper collages, or photomontages, are part of the art market that is seeing much interest amongst collectors. It is difficult to detect forgeries just through expertise. The use of NIR imaging offers a number of ways to identify forgeries or authenticate the collage non-destructively; from determining the glue used to the revealing of printing on the back of the pieces or paper, which often have been taken from books and magazines.
It is not every issue that one of our articles starts with a quotation in medieval English, and it is appropriate as two of our articles cover the use of spectroscopy in cultural heritage. This is yet another field where the rich information provided by spectroscopy, along with its non-destructive nature (for many techniques), portability and ability to generate chemical images make it the answer to many questions. Kate Nicholson, Andrew Beeby and Richard Gameson are responsible for the medieval English at the start of their article “Shedding light on medieval manuscripts”. They describe the general use of Raman spectroscopy for the analysis of historical artefacts, and, in particular, their work on medieval European manuscripts and 18th century watercolour pigments. They stess the importance of checking the actual laser power density to avoid damage to priceless artefacts.
Terahertz spectroscopy and imaging of Paleolithic cave etchings, 14th century paintings in a church and a mid-20th century Italian painting are all described. This helps demonstrate the versatility of the technique as well as its potential in cultural heritage preservation.
Much of the exterior surface of plants is covered by the cuticle. This plays a vital role in protecting the plant from water loss, attack by pests and pathogens and damage from UV radiation. Infrared spectroscopy is very useful in characterising cuticles, as we learn in “Infrared spectroscopy as a tool to study plant cuticles” by José Heredia-Guerrero, José Benítez, Eva Domínguez, Ilker Bayer, Roberto Cingolani, Athanassia Athanassioua and Antonio Heredia. The authors point out that, whilst still in its early stages, infrared spectroscopy has provided valuable information about the functional groups, chemical structure and arrangement and interactions of plant cuticle components.
Mark Tobin and colleagues describe “Fourier transform infrared spectroscopy and imaging of dragonfly, damselfly and cicada wing membranes”. Insects and plants have evolved highly specialised surfaces such as being highly water repellent or superhydrophobic, which also confers self cleaning properties. This is of interest to materials scientists to help in the development of manufactured materials with similar properties. High spatial resolution FT-IR spectroscopy and imaging provide useful information about the complex chemical patterning that contributes to this functionality.
Sampling on important works of art is not possible and this is the main reason why only non-invasive techniques, such as MSI, are becoming increasingly popular to assist with undertaking conservation decisions.
“Optical spectroscopy in therapy response monitoring: an awakening giant” by Arja Kullaa, Surya Singh, Jopi Mikkonen and Arto Koistinen looks at the important advances made by optical spectroscopy techniques, such as diffuse optical spectroscopic imaging (DOSI), Raman, diffuse reflectance and fluorescence spectroscopy, in changing how cancer is managed in patients. The ability to repeatedly monitor tumour dynamics to see how effective a particular treatment has been has enormous potential for us all.
“Elucidating structural and compositional changes in plant tissues and single cells by Raman spectroscopic imaging” is the topic of the next article by Batirtze Prats Mateu, Barbara Stefke, Marie-Theres Hauser and Notburga Gierlinger. Understanding plant cells is important for the best use of plants in traditional and new applications. Raman spectroscopic imaging represents one of the best ways to unravel the molecular structure in the native environment of plant tissues.
The authors describe “Multisensor hyperspectral imaging as a versatile tool for image-based chemical structure determination”. They describe the features of a software package that allows the combined analysis of hyperspectral data from different imaging techniques. This multisensor approach providing complementary information has many advantages.
Mid-infrared spectroscopic imaging is a rapidly emerging technique in biomedical research and clinical diagnostics that takes advantage of the unique molecular fingerprint of cells, tissue and biofluids to provide a rich biochemical image without the need for staining. Spectroscopic analysis allows for the objective classification of biological material at a molecular level.1 This “label free” molecular imaging technique has been applied to histology, cytology, surgical pathology, microbiology and stem cell research, and can be used to detect subtle changes to the genome, proteome and metabolome.2–4
It is important that places of archaeological and architectural importance need to be explored without damage. Atomic Dielectric Resonance (ADR) can be used for identifying sub-surface geological features. This technology1 uses a novel coherent beam, which has been used in the oil, gas and water industries, to provide information on what lies beneath the earth’s surface, without the need to drill cores.
The authors give us a “Review of nanoscale infrared spectroscopy applications to energy related materials”. Fuel cells, photovoltaics and specialised polymers for fracking are all considered.
This article describes an application of spectral imaging for the differentiation of tumour and normal cells. The authors also introduce the concept of a spectral barcode, which has had success with some tissues and has potential in others.