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@ARTICLE{Park:873324,
      author       = {Park, Heeyong and Uluca-Yazgi, Boran and Heumann, Saskia
                      and Schlögl, Robert and Granwehr, Josef and Heise, Henrike
                      and Schleker, Peter Philipp Maria},
      title        = {{H}eteronuclear cross-relaxation effect modulated by the
                      dynamics of {N}-functional groups in the solid state under
                      15{N} {DP}-{MAS} {DNP}},
      journal      = {Journal of magnetic resonance},
      volume       = {312},
      issn         = {1090-7807},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier},
      reportid     = {FZJ-2020-00642},
      pages        = {106688 -},
      year         = {2020},
      abstract     = {In a typical magic-angle spinning (MAS) dynamic nuclear
                      polarization (DNP) nuclear magnetic resonance (NMR)
                      experiment, several mechanisms are simultaneously involved
                      when transferring much larger polarization of electron spins
                      to NMR active nuclei of interest. Recently, specific
                      cross-relaxation enhancement by active motions under DNP
                      (SCREAM-DNP) [Daube et al. JACS 2016] has been reported as
                      one of these mechanisms. Thereby 13C enhancement with
                      inverted sign was observed in a direct polarization (DP) MAS
                      DNP experiment, caused by reorientation dynamics of methyl
                      that was not frozen out at 100 K. Here, we report on the
                      spontaneous polarization transfer from hyperpolarized 1H to
                      both primary amine and ammonium nitrogens, resulting in an
                      additional positive signal enhancement in the 15N NMR
                      spectra during 15N DP-MAS DNP. The cross-relaxation induced
                      signal enhancement (CRE) for 15N is of opposite sign
                      compared to that observed for 13C due to the negative sign
                      of the gyromagnetic ratio of 15N. The influence on CRE
                      efficiency caused by variation of the radical solution
                      composition and by temperature was also investigated.},
      cin          = {IEK-9 / ICS-6},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IEK-9-20110218 / I:(DE-Juel1)ICS-6-20110106},
      pnm          = {131 - Electrochemical Storage (POF3-131) / HITEC -
                      Helmholtz Interdisciplinary Doctoral Training in Energy and
                      Climate Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-131 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:32004819},
      UT           = {WOS:000518469000002},
      doi          = {10.1016/j.jmr.2020.106688},
      url          = {https://juser.fz-juelich.de/record/873324},
}