Abstract
Half-Integer High Spin (HIHS) systems with zero-field splitting (ZFS) parameters below 1 GHz are generally dominated by the spin |─1/2>→|+1/2 > central transition (CT). Accordingly, most pulsed Electron Paramagnetic Resonance (EPR) experiments are performed at this position for maximum sensitivity. However, in certain cases it can be desirable to detect higher spin transitions away from the CT in such systems. Here, we describe the use of frequency swept Wideband, Uniform Rate, Smooth Truncation (WURST) pulses for transferring spin population from the CT, and other transitions, of Gd(III) to the neighbouring higher spin transition |─3/2>→|─1/2 > at Q- and W-band frequencies. Specifically, we demonstrate this approach to enhance the sensitivity of 1H Mims Electron-Nuclear Double Resonance (ENDOR) measurements on two model Gd(III) aryl substituted 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) complexes, focusing on transitions other than the CT. We show that an enhancement factor greater than 2 is obtained for both complexes at Q- and W-band frequencies by the application of two polarising pulses prior to the ENDOR sequence. This is in agreement with simulations of the spin dynamics of the system during WURST pulse excitation. The technique demonstrated here should allow more sensitive experiments to be measured away from the CT at higher operating temperatures, and be combined with any relevant pulse sequence.
Original language | English |
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Article number | 107447 |
Number of pages | 9 |
Journal | JOURNAL OF MAGNETIC RESONANCE |
Volume | 351 |
DOIs | |
Publication status | Published - Jun 2023 |
Funding
Funding Information: A.M.B is grateful to The Royal Society and EPSRC for a Dorothy Hodgkin Fellowship (DH160004), and the University of Manchester for a Dame Kathleen Ollerenshaw Fellowship. A.M.B. also thanks the Royal Society of Chemistry for a Community for Analytical and Measurement Science (CAMS) fellowship. A.M.B. and C.J.R. thank The Royal Society for the Enhancement Award (RGF\EA\180287) which funded the doctoral studentship for C.J.R. C.J.R is further grateful to the Turing Scheme for funding to undertake a placement at the Weizmann Institute of Science. M.E.T thanks the BBSRC Doctoral Training Partnership 2, BB/M011208/1 for funding. This work was funded by the National Science Foundation USA-Israel Science Foundation program through BSF 2021617 (to D.G.). This research was made possible in part by the historic generosity of the Harold Perlman Family (D.G.). D. G. holds the Erich Klieger Professorial Chair in Chemical Physics. The authors acknowledge the Centre for Advanced Electron Spin Resonance at Oxford University, funded by the UK EPSRC (EP/L011972/1) and the EPSRC funded National Research facility at the University of Manchester (EP/W014521/1, NS/A000055/1, EP/V035231/1 and EP/S033181/1), for use of facility access and support. We are grateful to Prof. Christiane Timmel and Dr William Myers for help with experiments. A CC BY or equivalent license is applied to the Author Accepted Manuscript arising from this submission. Publisher Copyright: © 2023
All Science Journal Classification (ASJC) codes
- Biophysics
- Biochemistry
- Nuclear and High Energy Physics
- Condensed Matter Physics