Chemical Society Reviews Blog

You wouldn’t think it, but mid-infrared (IR) optical sensing technologies and I have a lot in common. I know. Unlikely as it seems that I – a small, Scottish, Beyoncé-wannabe – can overlap with a spectral regime known for its ability to directly characterise the structure of molecular species with finger print specificity, it is true. We are both children of the 80s and we are both suffering from ‘middle (child) syndrome’. As such, our potential often goes unnoticed and we are often overlooked by our bookends (visible and near IR in mid IR’s case; the 25-year-old ‘baby’ of the family and the first-born in my case). In this recent Chem Soc Rev article, Boris Mizaikoff at the University of Ulm in Germany champions the case for mid-IR sensors.

Miziakoff discusses how and why the field of mid-IR sensing has matured more slowly than visible and near IR technologies, as it requires a variety of optical components and materials compatible with  its spectral range, ultimately making it more costly than near IR. However, mid-IR offers unrivalled advantages in the level of molecular specificity, and discrimination and quantification of the components of complex mixtures.

Leading us through the developments in mid-IR sensing devices, Mizaikoff demonstrates that widespread use of these technologies is not only possible, but could enhance many emerging scientific concepts, together with practical applications such as security and surveillance, the monitoring of water quality, as well as use in the medical field.

As Mizaikoff writes, the future is promising for this sensing concept with its potential impact on the fields of environmental analysis and bioanalytics.

Read this HOT Chem Soc Rev article now in full:

Waveguide-enhanced mid-infrared chem/bio sensors
Boris Mizaikoff
Chem. Soc. Rev., 2013, Advance Article
DOI: 10.1039/C3CS60173K, Review Article

Sarah Brown is a guest web-writer for Chem Soc Rev.  Sarah hung up her lab coat after finishing her PhD and post-doctorate in nanotechnology for diagnostics and therapeutics, and now works in scientific publishing. When not trying to explain science through ridiculous analogies, you can often find her crocheting, baking or climbing, but not all at once. All views are her own.

Thinking about electronic spectra, spins and orbitals takes me back to my good old undergraduate days, when denim jackets worn with jeans were cool and having predictive text meant you had a top-of-the-range phone, and I would sit with my brain burning with wonder and confusion (and probably a small hangover) as these concepts and theories would be explained to me by the lecturer, affectionately nicknamed Disco Dave; so-called for the the entanglements and angles that his fingers and arms would get into, trying to explain such things.  And it worked.

Well, Disco Dave may be retired now but Peter Tanner, a well-known analytical chemistry expert from the Hong Kong Institute of Education, has published a Tutorial Review in Chem Soc Rev that looks to clarify misconceptions regarding the electronic spectra of tri-positive europium and cerium.  Tri-positive europium has attracted attention due to its potential application in sensors and time-gated bioimaging agents based on its optical emission spectra.  Tanner’s review gives the background to the electronic states, energy levels and transition intensities of lanthanide ions, and describes how to interpret the emission spectra of tri-positive europium in the solid state.

Professor Tanner has written this review to address, he says, the inaccurate descriptions of these spectra that are being amplified throughout the literature.  One such inaccuracy is the misuse of the term ‘Stokes shift.’  (This must be the chemistry equivalent of doing ‘hip hop’ moves to the disco tune ‘Saturday Night Fever.’)  The spectral properties 4f^N-4f^N lanthanide ions are often referred to, in the literature, to have large Stokes shifts; Professor Tanner explains that it is quite the contrary.  The Stokes shifts involved in such transitions are negligible, he explains, as the vibrational progressions are very weak and the maximum intensity lies in the 0-0 band.  In his Tutorial Review, we discover the alternative terms, Richardson shift and Denning shift, which are perhaps more appropriate– more consistently ‘disco.’

Read this HOT Chem Soc Rev Tutorial Review to find out more!

Some misconceptions concerning the electronic spectra of tri-positive europium and cerium
Peter A. Tanner
Chem. Soc. Rev., 2013, Advance Article
DOI: 10.1039/C3CS60033E

Sarah Brown is a guest web-writer for Chem Soc Rev.  Sarah hung up her lab coat after finishing her PhD and post-doctorate in nanotechnology for diagnostics and therapeutics, to become an assistant editor at the BMJ Publishing Group. When not trying to explain science through ridiculous analogies, you can often find her crocheting, baking or climbing, but not all at once.