Publication Date:
2019
Description:
〈p〉Pulsed dynamic nuclear polarization (DNP) techniques can accomplish electron-nuclear polarization transfer efficiently with an enhancement factor that is independent of the Zeeman field. However, they often require large Rabi frequencies and, therefore, high-power microwave irradiation. Here, we propose a new low-power DNP sequence for static samples that is composed of a train of microwave pulses of length 〈sub〉p〈/sub〉 spaced with delays 〈i〉d〈/i〉. A particularly robust DNP condition using a period 〈sub〉m〈/sub〉 = 〈sub〉p〈/sub〉 + 〈i〉d〈/i〉 set to ~1.25 times the Larmor period 〈sub〉Larmor〈/sub〉 is investigated which is a time-optimized pulsed DNP sequence (TOP-DNP). At 0.35 T, we obtained an enhancement of ~200 using TOP-DNP compared to ~172 with nuclear spin orientation via electron spin locking (NOVEL), a commonly used pulsed DNP sequence, while using only ~7% microwave power required for NOVEL. Experimental data and simulations at higher fields suggest a field-independent enhancement factor, as predicted by the effective Hamiltonian.〈/p〉
Electronic ISSN:
2375-2548
Topics:
Natural Sciences in General
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