Raman imaging of materials in the natural environment

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The vast majority of research on chemical responses by organisms to environmental change are conducted on model species and systems within controlled laboratory conditions. There are comparatively fewer studies on species living in the natural environment and it remains unclear how well insights gleaned from homogeneous conditions reflect processes operating in complex environments. Filling this gap requires laboratory-grade equipment that can be deployed in the field to reliably capture the full breadth of biodiversity and ecological processes within their complex and dynamic environmental context. Raman imaging spectroscopy provides exceptionally high-resolution, spatially explicit chemical information across a sample surface. The method has been used in plant sciences, for example, to uncover novel mechanisms, e.g. plant production of rare minerals. However, until now, confocal imaging Raman capability has been limited to laboratory use. Renishaw UK recently developed the first portable, confocal imaging Raman spectroscopy system, which - for the first time - can be used to map the chemistry of samples in the field with the highest possible spatial and spectral precision. This new technology will enable researchers to measure chemical structure and track processes in situ at a scale previously impossible; this new capability promises to shed light on heretofore hidden ecological components and processes. Fulfilling this potential firstly requires calibration of the field-based instrument (the Virsa) against a comparable laboratory-based system (the inVia).These Renishaw imaging Raman systems offer unique capability that makes them particularly well-suited for analysing environmental samples: LiveTrack focusing allows for chemical mapping over a rough surface without alteration or sample preparation; the ultra-fast detector enables large sample areas to be measured in minimal time; the detector is also highly sensitive which allows it to capture low concentration molecules within a heterogenous sample and even within an optically noisy environment; and its ability to target compounds for measurement further reduces analysis time, which allows for far greater replication than is feasible with standard chemical analysis methods. As with all Raman systems, they are able to capture both organic and inorganic molecules in living tissues because the method is insensitive to water (unlike infrared spectroscopy). Together, the inVia and Virsa systems offer novel capability that will create a step change in the type, precision and amount of chemical and structural information that can be obtained from environmental samples. We will take advantage of this capability to answer pressing questions about plant-soil feedbacks, soil microbial processes and organismal responses to stress. Within each project, we will calibrate the Virsa against measurements taken by the inVia in order to set the foundation for widespread adoption of Raman confocal imaging in field research. We will use a number of routes (training, publication, collaborations) to broaden awareness of the capability this novel equipment offers environmental research across the NERC remit.