Frequency Comb Spectroscopy for Volatile Organic Compound Emission Profiling

A fully funded (3.5 years) PhD position in the field of frequency comb laser spectroscopy for use in gas phase molecular sensing is available in the group of Dr Julia Lehman at the University of Birmingham.

Volatile organic compounds (VOCs) are abundant chemicals that are emitted by organisms in all terrestrial and marine ecosystems. The chemical composition of plant-emitted VOCs and their abundance can carry information about a plants' physiological status and the stresses to which they have been subjected. For example, plants release VOCs in response to infection by plant-parasitic nematodes. In this PhD project, you will work with the Lehman group and external collaborators in biology using a new technology (frequency comb laser spectroscopy) to detect and monitor VOCs in order to establish a VOC ‘fingerprint’ for nematode infection.

Infrared spectroscopy acts as a chemical ‘fingerprinting’ mechanism. However, VOCs emitted by plants are oftentimes in the low parts-per-billion (ppb) levels, which can test the limits of instrumentation sensitivity, and the overlapping infrared spectra of different VOCs can be an issue for low spectral resolution techniques. A frequency comb laser-Fourier transform infrared spectrometer (FC-FTIR) used in the Lehman group can reach the necessary ppb level molecular sensitivities by using a long laser-sample interaction path length, with the molecular selectivity being a result of the simultaneously broadband and high-resolution infrared laser. Machine learning and statistical analysis of healthy versus infected plant VOC emission profiles will aid in determining the relative health of the plant and potentially linking the emission profile to a specific plant pathogen.

This work addresses the current need to move towards a technology that is both sensitive and selective in order to identify a profile of plant VOCs emitted under different pathogen burdens, while still being general enough to detect all possible emitted VOCs (i.e. not targeting a specific VOC composition based on an assumed plant disease). This technology potentially allows the identification of a broad range of plant pathogens in a non-destructive manner, in real time. It therefore has impact across a wide range of biological disciplines in plant science and beyond, including such fields as atmospheric chemistry and health science.

Funding for this position is open to UK applicants and the 3.5 years studentship will commence in October 2023.

Previous hands-on experience in laser spectroscopy or gas phase chemistry is advantageous but not necessary. Enquiries and informal applications should include a C.V. and be addressed as soon as possible to Dr Julia Lehman (j.lehman@bham.ac.uk).