Details of Grant 

EPSRC Reference:	EP/N007875/1
Title:	Photochemical spin-hyperpolarization in confined environments
Principal Investigator:	Wedge, Dr CJ
Other Investigators:
Researcher Co-Investigators:
Project Partners:	Bruker University of Oxford
Department:	Physics
Organisation:	University of Warwick
Scheme:	First Grant - Revised 2009
Starts:	02 November 2015	Ends:	01 November 2016	Value (£):	98,996
EPSRC Research Topic Classifications:	Analytical Science
EPSRC Industrial Sector Classifications:	Healthcare
Related Grants:
Panel History:	Panel Date Panel Name Outcome 22 Jul 2015 EPSRC Physical Sciences Chemistry - July 2015 Announced
Summary on Grant Application Form
Nuclear Magnetic Resonance (NMR) is a tremendously powerful and versatile analytical technique for the investigation of the structure and dynamics of molecules from the simplest chemical species to complex biomolecules. The key limitation of NMR is that is suffers from low sensitivity because the obtainable nuclear spin polarization is small; lengthy signal averaging is therefore necessary making NMR slow which hinders new applications and because of finite equipment access even limits routine exploitation. This project will develop a new method for photochemically generating nuclear spin-hyperpolarization which by increasing sensitivity and reducing experiment times will provide the opportunity for a number of exciting new applications of NMR to be explored. To observe a magnetic resonance signal spin-polarization is required, that is more nuclear spins (which act like tiny bar magnets) must line up with than against the applied magnetic field (or vice-versa). Even in strong magnetic fields, however, typically less than one in ten thousand nuclei do so at room temperature. The polarization of electron spins is higher than that of nuclear spins (by ~660 versus protons) making them more sensitive probes of molecular environment, but most molecules don't have the unpaired electron spins needed to use electrons as probes directly. However, a number of Dynamic Nuclear Polarization (DNP) techniques are under development which aim to generate nuclear hyperpolarization (greater than equilibrium polarization) by transfer of polarization from thermally polarized electrons to nuclear spins. However, these techniques rely on microwave pumping of the electron spins which causes problems with sample heating, and for liquid state NMR the biggest gains come when long pumping periods are combined with rapid heating and dissolution of molecules polarized at very low temperatures. Such approaches generate large nuclear hyperpolarizations but cannot be rapidly repeated hence little time-saving is achieved. Such methods will not make feasible the time-consuming multi-dimensional experiments needed to examine complex biological molecules, or speed-up NMR analysis to enable high throughput screening for medical diagnostics. The project will use a short pulse of laser light to hyperpolarize electron spins to hundreds of times their thermal polarization and then rapidly transfer this large hyperpolarization to the nuclei, achieving nuclear spin-hyperpolarizations far in excess of those possible when using thermally polarized electrons. This will provide a room temperature nuclear hyperpolarization method that can be combined with the high repetition rates conventionally employed in NMR when signal averaging or incrementing experimental parameters. This project will exploit the as yet under-utilized Radical Triplet Pair Mechanism (RTPM) by which a stable radical interacts with a short-lived triplet state generated photochemically from a suitable precursor, resulting in electron spin-hyperpolarization of the radical. Such hyperpolarization can be conveniently observed by Electron Paramagnetic Resonance (EPR) spectroscopy. EPR will be used to investigate the key interactions giving rise to this effect, and in particular the effect of confining the radical and triplet molecules in cage-like structures on the size of the hyperpolarization generated. By restricting the relative separation of the radical and triplet molecules, and hence increasing their chances of encounter in solution, the electron hyperpolarization generated will be maximised. The effect of this encapsulation on the efficiency of the transfer to nuclear hyperpolarization will also be assessed. This project will test and further develop the underlying theory of the RTPM and provide a proof of principle that this method can be used as a new way to enhance sensitivity in NMR experiments, a result with potentially far reaching applications throughout analytical and medical science.
Key Findings
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Potential use in non-academic contexts
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Impacts
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Organisation Website:	http://www.warwick.ac.uk