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HP-EPR

NEW FRONTIERS IN HIGH PRESSURE ELECTRON PARAMAGNETIC RESONANCE

EPSRC Grant Reference: EP/C00891X/1

Principal Investigator: Dr ME Newton

Many of the processes monitored by EPR  (Electron Paramagnetic Resonance) are sensitive to the environment, for example to the temperature and pressure. Temperature is routinely varied in EPR experiments from -273 degrees Celsius to above 1000 degrees Celsius, but for many interesting studies very high pressures or rapid changes in pressures are required. No easy-to-use high pressure EPR probes with high sensitivity are available. The purpose of this project is to design, build and exploit a new type of high pressure EPR (HP-EPR) instrument. Very high pressures (e.g. 100,000 times atmospheric pressures) can only safely be generated in small volumes because of the risks of catastrophic explosions! Hence the EPR probe needs to be optimised for the study of small samples, and made compatible with high pressure equipment such as a diamond anvil cell. Diamond is the hardest known material, so diamonds make excellent anvils in a high pressure system capable of generating pressures in excess of 100,000 times atmospheres.

We propose to use a miniature microwave resonator (called a loop-gap-resonator), integrated with a hybrid high pressure cell which can be configured for use with: (i) diamond anvils (for the highest pressure studies); (ii) hard anvils which allow a sample to be squeezed along a unique axis (uniaxial stress), and (iii) a new cell which allows biological samples to be taken rapidly from atmospheric to moderately high pressures. The driving force to provide the high pressures comes either from a material which expands when a voltage is applied and compresses our sample cell (piezoelectric actuator) or from a hydraulic system. The construction is a real challenge!  Suitable materials must be found to allow safe and reliable operation and we must maintain high sensitivity to the presence of unpaired electrons in the sample. The development of this instrument would have an immediate and profound effect on UK research capability in a number of key areas of science and technology. We propose to study how the shape of proteins changes under pressure and how the shape influences their function, use high pressure to identify the structure of defects which affect the properties of new and technologically useful materials, and investigate by varying the pressure, the physics which will determine if individual unpaired electrons can be used as the building blocks of the computers of tomorrow. 

If you are interested in utilising High Pressure EPR in any collaborative research projects, or have any comments about this research then please contact Mark Newton (m.e.newton@warwick.ac.uk).