Show simple item record

Files in this item


Item metadata

dc.contributor.advisorSmith, Graham Murray
dc.contributor.authorZhao, Yujie
dc.description.abstractDynamic nuclear polarisation (DNP) is a process that transfers electron spin polarisation to nuclei and is a technique that has been widely used to improve nuclear magnetic resonance (NMR) sensitivity. This thesis presents the implementation of a DNP extension to a home-built high power pulsed electron paramagnetic resonance (EPR) spectrometer, HiPER, integrated with an arbitrary waveform generator (AWG), operating at 94 GHz. It describes the use of high-peak power inverting chirped pulses to increase the polarisation gradient of dipolar-coupled electrons, where static cross-effect DNP enhancements of 340 are achieved within 3 seconds at 65 K with a mixture of 4-amino TEMPO and DNP juice. Several other nitroxide radical polarising agents are also investigated and systematic study into the DNP temperature dependence for different polarising agents reveals the impact of spectral diffusion and the molecular structure of polarising agents. In addition, for the first time at 94 GHz, a comparative study is made of different coherent pulsed solid-effect DNP schemes including XiX, TPPM, and the adiabatic solid-effect. An ENDOR upgrade to the DNP/EPR spectrometer is also described, and preliminary room-temperature ¹H ENDOR and low-temperature ¹⁹F ENDOR experiments presented, where a combined approach involving shaped pulse excitation and data processing at an intermediate frequency in down-conversion for DC suppression yields a threefold enhancement in SNR. Finally, a brief summary to ongoing projects on magnet shimming, transition metal DNP and DNP characterisation for lithium dendrites is provided.en_US
dc.description.sponsorship"This work was supported by the China Scholarship Council (CSC) [grant number: 201906320043]; and the University of St Andrews. Funds acquired for individual research projects encapsulated in this thesis are acknowledged within each respective chapter."--Fundingen
dc.subjectDynamic nuclear polarisationen_US
dc.subjectElectron paramagnetic resonanceen_US
dc.subjectElectron-nuclear double resonanceen_US
dc.subjectMagnetic resonanceen_US
dc.subjectNuclear magnetic resonanceen_US
dc.titleMethodology development of high sensitivity pulsed EPR and DNPen_US
dc.contributor.sponsorUniversity of St Andrewsen_US
dc.contributor.sponsorChina Scholarship Council (CSC)en_US
dc.type.qualificationnamePhD Doctor of Philosophyen_US
dc.publisher.institutionThe University of St Andrewsen_US
dc.rights.embargoreasonThesis restricted in accordance with University regulations. Restricted until 1 February 2025en

This item appears in the following Collection(s)

Show simple item record