Expert Exchange: High-resolution Raman spectroscopy of silicified organic materials

Europlanet 2024 RI’s Expert Exchange Programme aims to support the planetary community to share expertise and best practice, and to prepare new facilities and services. The programme provides funding for short visits (up to one week). 

Keyron Hickman-Lewis of the Natural History Museum, London (UK), visited the team of Barbara Cavalazzi at the Department of Biological, Geological and Environmental Sciences, Università di Bologna (Italy), from 6-14 January 2024 to reinforce practical abilities with Raman spectroscopy of geological materials, developed during a previous Expert Exchange.

During a previous Europlanet Expert Exchange visit to Prof. Barbara Cavalazzi at the Università di Bologna, (January 2022), I was trained in the practical use of the new WITec Raman spectroscopy instrument at the BiGeA Department. During this follow-up visit, we advanced our collaboration through discussions of ongoing projects and used the Raman instrument to perform high-resolution mapping (< 1 μm x–y spatial resolution) of silicified organic materials preserved within Palaeozoic and Precambrian cherts, which are considered environmental analogues for specific hydrothermal and silica-rich settings on the early Mars.

Obtaining high-resolution maps of these materials is crucial to understanding spatial chemical heterogeneities that may reflect differences in the nature of precursor biomass. We plan to correlate the datasets with those obtained prior to the Expert Exchange visit using infrared microspectroscopy at my home institution (Natural History Museum, London). Initial data treatment during the visit to Bologna indicated chemical heterogeneities within different portions of the analyses organic materials. This was confirmed by obtaining single spectra analyses within difference regions of the studied materials.

In the coming months, Prof. Cavalazzi and I will continue to collaborate on these data, using advanced data treatment tools and software to fully explore the statistical significance of spectral variations observed in these fossilised organic materials.

During the visit, we also discussed how the analytical approach developed may be used on other – more controversial – materials. For example, such high-resolution analytical approaches followed by advanced data treatment will be the keystone of analyses conducted on samples brought to Earth following Mars Sample Return. Developing technical approaches and data treatment workflows in advance of the analyses of these materials is essential.

During the visit, I was also able to exchange with a number of other members of Prof. Cavalazzi’s team and department, and have initiated one further new collaboration. Since Prof. Cavalazzi and I co-supervise a student, this visit was also an opportunity to discuss together the analytical results obtained during our student’s visit to The Natural History Museum in late 2023. Progress was made on preparing these data for publication in the near future. Finally, we discussed detailed plans for future collaborations, in particular how Raman spectroscopy at different wavelengths may be harnessed as a tool for advanced analysis of silicified organic materials. This work will be developed during 2024, following the installation of a new laser at the Bologna Raman spectroscopy facility.

Overall, the visit was a success and allowed us to advance our ongoing collaboration in Earth and planetary sciences, with a strong focus on the considerations and preparation necessary for Mars Sample Return.

Expert Exchange Objectives covered by this visit: Training for Transnational Access, Early Career Support.

Find out more about the Europlanet Expert Exchange Programme.