The focus of my PhD has been the development of new instrumentation for UV polarised spectroscopic methods, especially that of circular dichroism (CD). Whilst instrument design is an unusual field of research (especially for a chemist!) I feel it is one of great importance to the scientific process. The instruments that scientists employ to study the world around us are our eyes and ears, enabling us to view objects from the angstrom level to distant galaxies. In many ways, it could be argued that the limiting factor for the majority of research is the methods that we can employ. By improving these methods, we naturally enhance the quality of our research and further understanding.
Capillary circular dichroism (CaCD)
One of the key problems with circular dichroism as a technique is its relatively high sample requirments for each reading. In order to address this problem, we have been working on using extruded quartz capillaries as an inexpensive alternative sample holder to the rectangular quartz cuvette. After modification of the light beam with a double convex lens, we have managed to lower sample requirments significantly, to a mininum of 3 µl. This sample saving comes at no loss of spectral quality. This work has been published in the journal Chirality, which can be found here. Further work taking advantage of the optical properties of quartz capillaries is ongoing.
Automated multi-sample Circular Dichroism (AMS-CD)
In collaboration with Tim Dafforn of Birmingham University we are currently developing a new method of collecting CD data, suitable for analysing large numbers of samples. This is to take advanatge of the short aquisition time for CD spectra, which remains one of the most attractive features of CD as a technique. At this current time we have developed a fully working prototype that has shown great promise. Future developments should be coming soon- watch this space!
Etched cuvette Circular Dichroism (EcCD)
Current demountable small (10/20 µm) path-length cuvettes are currently very inaccurate, detrimentally affecting CD spectral quality. Using optical polishing and acid etching techniques, in collaboration with Crystal Precision Optics we have now designed a new form of demountable small pathlength cuvette that is highly accurate and easy to use. This instrument is currently undergoing testing.
Whole Organism Linear Dichroism
With recent advances in LD instrumentation, we now believe it is possible to obtain LD data from an entire organism! (Well, a bacterium at least). Initial results look very promising indeed. Acquiring an LD signal for an entire organism would open up the possibility for an entire new branch of LD spectroscopy.
UV optical materials
One of the biggest limiting factors in UV instrument design is the need for optically transmitting materials. This is especially important when looking at SRCD, as much of the benefits gained from acquiring spectra at a beamline are lost if the sample holder cannot transmit light at that wavelength. For this reason, we are also investigating the use of fibre optical cabling in polarised spectroscopy.