Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization

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Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization. / Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva.

In: Journal of Magnetic Resonance, Vol. 258, 2015, p. 102-120.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Harvard

Mentink-Vigier, F, Akbey, Ü, Oschkinat, H, Vega, S & Feintuch, A 2015, 'Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization', Journal of Magnetic Resonance, vol. 258, pp. 102-120. https://doi.org/10.1016/j.jmr.2015.07.001

APA

Mentink-Vigier, F., Akbey, Ü., Oschkinat, H., Vega, S., & Feintuch, A. (2015). Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization. Journal of Magnetic Resonance, 258, 102-120. https://doi.org/10.1016/j.jmr.2015.07.001

CBE

Mentink-Vigier F, Akbey Ü, Oschkinat H, Vega S, Feintuch A. 2015. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization. Journal of Magnetic Resonance. 258:102-120. https://doi.org/10.1016/j.jmr.2015.07.001

MLA

Mentink-Vigier, Frederic et al. "Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization". Journal of Magnetic Resonance. 2015, 258. 102-120. https://doi.org/10.1016/j.jmr.2015.07.001

Vancouver

Mentink-Vigier F, Akbey Ü, Oschkinat H, Vega S, Feintuch A. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization. Journal of Magnetic Resonance. 2015;258:102-120. https://doi.org/10.1016/j.jmr.2015.07.001

Author

Mentink-Vigier, Frederic ; Akbey, Ümit ; Oschkinat, Hartmut ; Vega, Shimon ; Feintuch, Akiva. / Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization. In: Journal of Magnetic Resonance. 2015 ; Vol. 258. pp. 102-120.

Bibtex

@article{1ed58a6a5c424c08aba8d0a30f926257,
title = "Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization",
abstract = "Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160 K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This study also shows the complexity of the MAS-DNP process and therefore the necessity to rely on numerical simulations for understanding parametric dependencies of the enhancements. Finally an extension of the spin system up to five spins allowed us to probe the first steps of the transfer of polarization from the nuclei coupled to the electrons to further away nuclei, demonstrating a decrease in the spin-diffusion barrier under MAS conditions.",
keywords = "AMUPOL, Biradical, Cross-Effect, Dynamic Nuclear Polarization, Hyperfine coupling, Landau-Zener, Magic Angle Spinning, MAS-DNP, Nitroxide, Nuclear magnetic resonance, Relaxation, Simulations, Solid-Effect, Solid-State, TEMPOL, TOTAPOL",
author = "Frederic Mentink-Vigier and {\"U}mit Akbey and Hartmut Oschkinat and Shimon Vega and Akiva Feintuch",
year = "2015",
doi = "10.1016/j.jmr.2015.07.001",
language = "English",
volume = "258",
pages = "102--120",
journal = "Journal of Magnetic Resonance",
issn = "1090-7807",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization

AU - Mentink-Vigier, Frederic

AU - Akbey, Ümit

AU - Oschkinat, Hartmut

AU - Vega, Shimon

AU - Feintuch, Akiva

PY - 2015

Y1 - 2015

N2 - Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160 K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This study also shows the complexity of the MAS-DNP process and therefore the necessity to rely on numerical simulations for understanding parametric dependencies of the enhancements. Finally an extension of the spin system up to five spins allowed us to probe the first steps of the transfer of polarization from the nuclei coupled to the electrons to further away nuclei, demonstrating a decrease in the spin-diffusion barrier under MAS conditions.

AB - Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160 K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This study also shows the complexity of the MAS-DNP process and therefore the necessity to rely on numerical simulations for understanding parametric dependencies of the enhancements. Finally an extension of the spin system up to five spins allowed us to probe the first steps of the transfer of polarization from the nuclei coupled to the electrons to further away nuclei, demonstrating a decrease in the spin-diffusion barrier under MAS conditions.

KW - AMUPOL

KW - Biradical

KW - Cross-Effect

KW - Dynamic Nuclear Polarization

KW - Hyperfine coupling

KW - Landau-Zener

KW - Magic Angle Spinning

KW - MAS-DNP

KW - Nitroxide

KW - Nuclear magnetic resonance

KW - Relaxation

KW - Simulations

KW - Solid-Effect

KW - Solid-State

KW - TEMPOL

KW - TOTAPOL

UR - http://www.scopus.com/inward/record.url?scp=84938057730&partnerID=8YFLogxK

U2 - 10.1016/j.jmr.2015.07.001

DO - 10.1016/j.jmr.2015.07.001

M3 - Journal article

VL - 258

SP - 102

EP - 120

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

SN - 1090-7807

ER -