Enhanced dynamic nuclear polarization by the integrated solid effect

Henstra, A.; Dirksen, Peter; Wenckebach, W.Th.

doi:10.1016/0375-9601(88)90950-4

Cited by 137 publications

(114 citation statements)

References 2 publications

Supporting

Mentioning

113

Contrasting

Order By: Relevance

“…To date, there are a handful of sequences for pulsed DNP including nuclear orientation via electron spin locking (NOVEL), 33 the integrated solid effect (ISE), 34 DNP in the nuclear rotating frame (NRF) DNP, 35 and dressed state solid effect (DSSE). 36 Neither NRF DNP nor DSSE requires a strong microwave field.…”

Section: Introductionmentioning

confidence: 99%

“…NOVEL was soon replaced by ISE which gives a much higher efficiency due to the adiabatic sweep of the magnetic field. 34,[38][39][40] Note that both of these samples were especially chosen to demonstrate the NOVEL or ISE effect. Thus, one of our goals in the results reported here was to investigate the potential of the NOVEL sequence in samples used in current applications of DNP in NMR, i.e., samples doped with a few tens of mM of stable free radicals such as the narrow-line species 1,3-bisdiphenylene-2-phenylallyl (BDPA) or nitroxides, both of which are used in contemporary CW DNP experiments.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Time domain DNP with the NOVEL sequence

Can

Walish

Swager

et al. 2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

We present results of a pulsed dynamic nuclear polarization (DNP) study at 0.35 T (9.7 GHz/ 14.7 MHz for electron/ 1 H Larmor frequency) using a lab frame-rotating frame cross polarization experiment that employs electron spin locking fields that match the 1 H nuclear Larmor frequency, the so called NOVEL (nuclear orientation via electron spin locking) condition. We apply the method to a series of DNP samples including a single crystal of diphenyl nitroxide (DPNO) doped benzophenone (BzP), 1,3-bisdiphenylene-2-phenylallyl (BDPA) doped polystyrene (PS), and sulfonated-BDPA (SA-BDPA) doped glycerol/water glassy matrices. The optimal Hartman-Hahn matching condition is achieved when the nutation frequency of the electron matches the Larmor frequency of the proton, ω 1S = ω 0I , together with possible higher order matching conditions at lower efficiencies. The magnetization transfer from electron to protons occurs on the time scale of ∼100 ns, consistent with the electron-proton couplings on the order of 1-10 MHz in these samples. In a fully protonated single crystal DPNO/BzP, at 270 K, we obtained a maximum signal enhancement of ε = 165 and the corresponding gain in sensitivity of ε(T 1 /T B ) 1/2 = 230 due to the reduction in the buildup time under DNP. In a sample of partially deuterated PS doped with BDPA, we obtained an enhancement of 323 which is a factor of ∼3.2 higher compared to the protonated version of the same sample and accounts for 49% of the theoretical limit. For the SA-BDPA doped glycerol/water glassy matrix at 80 K, the sample condition used in most applications of DNP in nuclear magnetic resonance, we also observed a significant enhancement. Our findings demonstrate that pulsed DNP via the NOVEL sequence is highly efficient and can potentially surpass continuous wave DNP mechanisms such as the solid effect and cross effect which scale unfavorably with increasing magnetic field. Furthermore, pulsed DNP is also a promising avenue for DNP at high temperature. C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4927087] INTRODUCTIONDynamic nuclear polarization (DNP) is a process whereby the large polarization present in an electron spin reservoir of a paramagnetic polarizing agent is transferred via microwave irradiation to nuclei, thereby enhancing the nuclear spin polarization. The initial mechanism supporting the DNP process, the Overhauser effect (OE), was proposed in 1953 1 and confirmed experimentally 2,3 in samples with mobile electrons (i.e., metals, solutions, and 1D conductors). In contrast, in insulating solids, such as glycerol/water glasses and biological samples, the OE was thought to be forbidden, but we have recently observed Overhauser enhancements using polarizing agents with narrow EPR spectra that exhibit strong 1 H−e − hyperfine couplings. 4 Furthermore, in these sorts of samples, DNP processes can also be mediated by three other mechanisms -the solid effect (SE), 5,6 the cross effect, 7-11 and/or thermal mixing. 12 Initially, the primary application of DNP was preparation of p...

show abstract

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Time domain DNP with the NOVEL sequence

Can

Walish

Swager

et al. 2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Firstly, electron population difference is produced among a triplet state of photo-excited aromatic molecules [7]. Then, this electron population difference is transferred to protons by so-called cross-polarization technique [8]. The target polarization during the beam-time was found to be 13.8±2.7% on average.…”

Section: P+ 68 He Analyzing Power Measurementmentioning

confidence: 99%

“…Measurements of the analyzing powers for p+ 6,8 He elastic scattering were carried out at the RIKEN Accelerator Research Facility (RARF) in 2005 and 2007 using the RIKEN Projectilefragment Separator (RIPS) [5]. Details of the p+ 6 He elastic-scattering measurement are described here.…”

Section: P+ 68 He Analyzing Power Measurementmentioning

confidence: 99%

Elastic Scattering of Neutron-Rich Helium Isotopes from Polarized Protons at 71 MeV/A

Sakaguchi

Uesaka

Kawabata

et al. 2011

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Abstract. The vector analyzing power has been measured for the elastic scattering of neutronrich 6 He and 8 He from polarized protons at 71 MeV/A making use of a newly constructed solid polarized proton target operated in a low magnetic field of 0.1 T and at a relatively high temperature of 100 K. An optical model analysis revealed that the spin-orbit potentials for 6 He and 8 He are characterized by shallow and long-ranged shape compared with the global systematics of stable nuclei. Such a characteristics reflect a diffused density distribution of the neutron-rich isotopes.

show abstract

“…If the EPR line width is broader than ω n , both (W ± ) transitions may be excited at the same time and complete or partial cancellation of polarization is the result. This is also known as the Differential Solid Effect [35]. The energy diagram for a coupled electron and nuclear spin to understand Solid Effect DNP.…”

mentioning

confidence: 99%