January 18, 1990 - January 18, 2023

  • Date:16ThursdayJanuary 2020

    Solid State NMR of low abundant quadrupolar nuclei achieved through extended coherence lifetimes

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    09:30 - 10:30
    Gerhard M.J. Schmidt Lecture Hall
    Dr. Daniel Jardon-Alvarez
    Dept. Materials and Interfaces, WIS
    Department of Materials and Interfaces
    The Helen and Martin Kimmel Institute for Magnetic Resonance
    AbstractShow full text abstract about Less is more! By using extremely low power refocusing π puls...»
    Less is more! By using extremely low power refocusing π pulses in echo train sequences the coherence lifetime, T2, of the central transition of half-integer quadrupolar nuclei can be largely extended. This effect is particularly impactful in systems dilute in NMR active nuclei, where sources of decoherence are scarce. Crucial to this lifetime extension is the avoidance of coherence transfer to short-lived non-symmetric “killing” transitions. For 17O in polycrystalline α-quartz we were able to retain coherent magnetization for over four minutes on the transverse plane. This translates into enormous sensitivity gains for echo train acquisition after addition of the long living echoes. By combining satellite population transfer schemes with a low power CPMG on 17O in quartz, we obtain over a 1000-fold sensitivity enhancement compared to a spectrum from a free induction decay acquired at a more typical rf field strength. This enhancement allows the acquisition of a highly resolved 17O spectrum within less than one hour, despite its low natural abundance and a spin-lattice relaxation time of approximately 900 s. In this talk I will present a thorough analysis of the effects of pulse power on the echo intensity, coherence lifetime and line shape integrity. Finally, we apply this approach on various crystalline and glassy inorganic solids, including other low sensitivity nuclei, such as 33S and 45Ca, showing that it can be beneficial for a large number of systems.