Junior Professor, Department of Chemistry
I am currently a junior professor in the Department of Chemistry, École Normale Supérieure. My research expertise is in methods development in solid-state NMR and Dynamic Nuclear Polarization (DNP). I am mainly interested in developing both theory and instrumentation for pulsed dynamic nuclear polarization, which will be applied to study inorganic materials and biomolecules. I serve as an editor in the Magnetic Resonance journal, and run ssNMR/DNP Zoominar.
Here are my Google Scholar, Twitter, YouTube channel, and GitHub site. Additionally, if you want to learn more about me, here is an interview conducted by ENS.
Contact & Office Location
Email: kong-ooi.tan (a) ens.psl.eu . My office is ES 106 in the Department of Chemistry at ENS, 24 Rue Lhomond, 75005 Paris. Click here for the lab location.
Teaching Activities
I am teaching two courses: (1) NMR (Basic solid-state NMR) for M1 students at ENS (2) MR (solid-state NMR/EPR/DNP) for M2 students at PSL.
Team Members
- Postdoc: Zhenfeng Pang
- PhD Student: Utsab Banerjee, Jake Lumsden
- Alumni: Ngoc Diep Le (M1), Cyriaque Amerein (L3)
- Support from CNRS research engineers: Nicolas Birlirakis and Mathieu Baudin
Education and Professional Career
- 2020-now Junior Professor (tenure-track), Ecole Normale Superieure, France
- 2016-2020 Postdoc in Prof. Robert G. Griffin’s group, MIT, USA
- 2011-2016 PhD student in Prof. Dr. Matthias Ernst / Prof. Dr. Beat H. Meier’s group, ETH Zurich, Switzerland
- 2007-2011 Undergraduate in Physics, Imperial College London, UK
Fundings and Grants
- PSL Junior Fellows, 2022
- ANR JCJC: HFPulsedDNP (ANR-21-CE29-0019), 2021
- ANR Tremplin ERC: PulsedDNP (ANR-20-ERC9-0008), 2021
- Respore petit équipement projet n°339299, 2021
- ENS Action Incitative, 2020
Publication
2023 |
In-house fabrication of 1.3 to 7 mm MAS drive caps using desktop 3D printers Article de journal Cyriaque Amerein; Utsab Banerjee; Zhenfeng Pang; Wenqing Lu; Vanessa Pimenta; Kong Ooi Tan Journal of Magnetic Resonance, 2023. @article{Amerein2023, title = {In-house fabrication of 1.3 to 7 mm MAS drive caps using desktop 3D printers}, author = {Cyriaque Amerein and Utsab Banerjee and Zhenfeng Pang and Wenqing Lu and Vanessa Pimenta and Kong Ooi Tan }, url = {https://www.chimie.ens.fr/wp-content/uploads/2023/02/1-s2.0-S1090780723000265-main.pdf}, doi = {10.1016/j.jmr.2023.107391}, year = {2023}, date = {2023-02-06}, journal = {Journal of Magnetic Resonance}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2022 |
Room-Temperature Quantitative Quantum Sensing of Lithium Ions with a Radical-Embedded Metal–Organic Framework Article de journal Lei Sun; Luming Yang; Jin-Hu Dou; Jian Li; Grigorii Skorupskii; Michael Mardini; Kong Ooi Tan; Tianyang Chen; Chenyue Sun; Julius J. Oppenheim; Robert G. Griffin; Mircea Dincă; Tijana Rajh J. Am. Chem. Soc., 144 , p. 19008−19016, 2022. @article{Sun2022, title = {Room-Temperature Quantitative Quantum Sensing of Lithium Ions with a Radical-Embedded Metal\textendashOrganic Framework}, author = {Lei Sun and Luming Yang and Jin-Hu Dou and Jian Li and Grigorii Skorupskii and Michael Mardini and Kong Ooi Tan and Tianyang Chen and Chenyue Sun and Julius J. Oppenheim and Robert G. Griffin and Mircea Dinc\u{a} and Tijana Rajh}, url = {https://pubs.acs.org/doi/pdf/10.1021/jacs.2c07692}, doi = {10.1021/jacs.2c07692}, year = {2022}, date = {2022-10-06}, journal = { J. Am. Chem. Soc.}, volume = {144}, pages = {19008−19016}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling Article de journal Kong Ooi Tan; Luming Yang; Michael Mardini; Choon Boon Cheong; Benoit Driesschaert; Mircea Dincă; Robert Guy Griffin Chemistry – A European Journal, 2022. @article{https://doi.org/10.1002/chem.202202556, title = {Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling}, author = {Kong Ooi Tan and Luming Yang and Michael Mardini and Choon Boon Cheong and Benoit Driesschaert and Mircea Dinc\u{a} and Robert Guy Griffin}, url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202202556}, doi = {https://doi.org/10.1002/chem.202202556}, year = {2022}, date = {2022-09-11}, journal = {Chemistry \textendash A European Journal}, abstract = {Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway\textemdashfrom the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest\textemdashremains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can enable direct NMR detection of these nuclei. We achieved an ~80% improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of 𝜀 ~ 90 and ~11% higher NMR intensity using electron decoupling on paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway—from the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest—remains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can enable direct NMR detection of these nuclei. We achieved an ~80% improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of 𝜀 ~ 90 and ~11% higher NMR intensity using electron decoupling on paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF). |
Designing broadband pulsed dynamic nuclear polarization sequences in static solids Article de journal Nino Wili; Anders Bodholt Nielsen; Laura Alicia Völker; Lukas Schreder; Niels Chr. Nielsen; Gunnar Jeschke; Kong Ooi Tan Science Advances, 8 , 2022. @article{Wili2022, title = {Designing broadband pulsed dynamic nuclear polarization sequences in static solids}, author = {Nino Wili and Anders Bodholt Nielsen and Laura Alicia V\"{o}lker and Lukas Schreder and Niels Chr. Nielsen and Gunnar Jeschke and Kong Ooi Tan}, url = {https://www.science.org/doi/10.1126/sciadv.abq0536}, doi = {DOI: 10.1126/sciadv.abq0536}, year = {2022}, date = {2022-07-15}, journal = {Science Advances}, volume = {8}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
A unified description for polarization-transfer mechanisms in magnetic resonance in static solids: Cross polarization and DNP Article de journal Zhenfeng Pang; Sheetal Jain; Chen Yang; Xueqian Kong; Kong Ooi Tan The Journal of Chemical Physics, 156 (24), p. 244109, 2022. @article{2022Pang, title = {A unified description for polarization-transfer mechanisms in magnetic resonance in static solids: Cross polarization and DNP}, author = {Zhenfeng Pang and Sheetal Jain and Chen Yang and Xueqian Kong and Kong Ooi Tan }, url = {https://aip.scitation.org/doi/abs/10.1063/5.0092265}, doi = {10.1063/5.0092265}, year = {2022}, date = {2022-06-24}, journal = {The Journal of Chemical Physics}, volume = {156}, number = {24}, pages = {244109}, abstract = {Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron\textendashnucleus distance measurements\textemdashsuch as routine dipolar-recoupling experiments in solid-state NMR. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron–nucleus distance measurements—such as routine dipolar-recoupling experiments in solid-state NMR. |
Integrated, Stretched, and Adiabatic Solid Effects Article de journal Yifan Quan; Jakob Steiner; Yifu Ouyang; Kong Ooi Tan; W. Thomas Wenckebach; Patrick Hautle; Robert G. Griffin J. Phys. Chem. Lett, 13 , p. 5751, 2022. @article{Quan2022, title = {Integrated, Stretched, and Adiabatic Solid Effects}, author = {Yifan Quan and Jakob Steiner and Yifu Ouyang and Kong Ooi Tan and W. Thomas Wenckebach and Patrick Hautle and Robert G. Griffin }, url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.2c01147}, doi = {10.1021/acs.jpclett.2c01147}, year = {2022}, date = {2022-06-17}, journal = {J. Phys. Chem. Lett}, volume = {13}, pages = {5751}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Observation of a Four-Spin Solid Effect Article de journal Kong Ooi Tan; Robert G. Griffin J. Chem. Phys., 2022. @article{Tan2022FSSE, title = {Observation of a Four-Spin Solid Effect}, author = {Kong Ooi Tan and Robert G. Griffin }, url = {https://aip.scitation.org/doi/abs/10.1063/5.0091663}, doi = {10.1063/5.0091663}, year = {2022}, date = {2022-04-12}, journal = {J. Chem. Phys.}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2021 |
Overhauser Dynamic Nuclear Polarization with Selectively Deuterated BDPA Radicals Article de journal Léo Delage-Laurin; Ravi Shankar Palani; Natalie Golota; Michael Mardini; Yifu Ouyang; Kong Ooi Tan; Timothy M. Swager; Robert G. Griffin J. Am. Chem. Soc., 143 (48), p. 20281–20290, 2021. @article{Tan2021OE, title = {Overhauser Dynamic Nuclear Polarization with Selectively Deuterated BDPA Radicals}, author = {L\'{e}o Delage-Laurin and Ravi Shankar Palani and Natalie Golota and Michael Mardini and Yifu Ouyang and Kong Ooi Tan and Timothy M. Swager and Robert G. Griffin}, url = {https://pubs.acs.org/doi/abs/10.1021/jacs.1c09406}, doi = {10.1021/jacs.1c09406}, year = {2021}, date = {2021-11-23}, journal = {J. Am. Chem. Soc.}, volume = {143}, number = {48}, pages = {20281\textendash20290}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Time domain DNP at 1.2 T Article de journal T V Can; Kong Ooi Tan; C Yang; R T Weber; R G Griffin Journal of Magnetic Resonance, 329 , p. 107012, 2021, ISSN: 1090-7807. @article{CAN2021107012, title = {Time domain DNP at 1.2 T}, author = {T V Can and Kong Ooi Tan and C Yang and R T Weber and R G Griffin}, url = {https://www.sciencedirect.com/science/article/pii/S1090780721001014}, doi = {https://doi.org/10.1016/j.jmr.2021.107012}, issn = {1090-7807}, year = {2021}, date = {2021-01-01}, journal = {Journal of Magnetic Resonance}, volume = {329}, pages = {107012}, abstract = {We present the results of an experimental pulsed DNP study at 1.2 T (33.5 GHz/51 MHz electron and 1H Larmor frequencies, respectively). The results include a comparison of constant-amplitude NOVEL (CA-NOVEL), ramped-amplitude NOVEL (RA-NOVEL) and the frequency-swept integrated solid effect (FS-ISE) experiments all of which were performed at the NOVEL matching condition, ω1S=ω0I, where ω1S is the electron Rabi frequency andω0I the proton Larmor frequency. To the best of our knowledge, this is the first pulsed DNP study carried out at field higher than X-band (0.35 T) using the NOVEL condition. A combination of high microwave power (∼150 W) and a microwave cavity with a high Q (∼500) allowed us to satisfy the NOVEL matching condition. We also observed stretched solid effect (S2E) contributions in the Zeeman field profiles when chirped pulses are applied. Furthermore, the high quality factor of the cavity limits the concentration of the radical to ∼5 mM and generates a hysteresis in the FS-ISE experiments. Nevertheless, we observe very high DNP enhancements that are comparable to the results at X-band. These promising outcomes suggest the importance of further studies at even higher fields that delineate the instrumentation and methods required for time domain DNP.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present the results of an experimental pulsed DNP study at 1.2 T (33.5 GHz/51 MHz electron and 1H Larmor frequencies, respectively). The results include a comparison of constant-amplitude NOVEL (CA-NOVEL), ramped-amplitude NOVEL (RA-NOVEL) and the frequency-swept integrated solid effect (FS-ISE) experiments all of which were performed at the NOVEL matching condition, ω1S=ω0I, where ω1S is the electron Rabi frequency andω0I the proton Larmor frequency. To the best of our knowledge, this is the first pulsed DNP study carried out at field higher than X-band (0.35 T) using the NOVEL condition. A combination of high microwave power (∼150 W) and a microwave cavity with a high Q (∼500) allowed us to satisfy the NOVEL matching condition. We also observed stretched solid effect (S2E) contributions in the Zeeman field profiles when chirped pulses are applied. Furthermore, the high quality factor of the cavity limits the concentration of the radical to ∼5 mM and generates a hysteresis in the FS-ISE experiments. Nevertheless, we observe very high DNP enhancements that are comparable to the results at X-band. These promising outcomes suggest the importance of further studies at even higher fields that delineate the instrumentation and methods required for time domain DNP. |
DNPSOUP: A simulation software package for dynamic nuclear polarization Article de journal Chen Yang; Kong Ooi Tan; R G Griffin Journal of Magnetic Resonance, p. 107107, 2021, ISSN: 1090-7807. @article{YANG2021107107, title = {DNPSOUP: A simulation software package for dynamic nuclear polarization}, author = {Chen Yang and Kong Ooi Tan and R G Griffin}, url = {https://www.sciencedirect.com/science/article/pii/S1090780721001968}, doi = {https://doi.org/10.1016/j.jmr.2021.107107}, issn = {1090-7807}, year = {2021}, date = {2021-01-01}, journal = {Journal of Magnetic Resonance}, pages = {107107}, abstract = {Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses. |
2020 |
Adiabatic Solid Effect Article de journal Kong Ooi Tan; Ralph T Weber; Thach Van Can; Robert G Griffin The Journal of Physical Chemistry Letters, 11 (9), p. 3416–3421, 2020, ISSN: 1948-7185. @article{Tan2020, title = {Adiabatic Solid Effect}, author = {Kong Ooi Tan and Ralph T Weber and Thach Van Can and Robert G Griffin}, url = {https://pubs.acs.org/doi/10.1021/acs.jpclett.0c00654}, doi = {10.1021/acs.jpclett.0c00654}, issn = {1948-7185}, year = {2020}, date = {2020-05-01}, journal = {The Journal of Physical Chemistry Letters}, volume = {11}, number = {9}, pages = {3416--3421}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2019 |
Pulsed Dynamic Nuclear Polarization incollection Kong Ooi Tan; Sudheer Jawla; Richard J Temkin; Robert G Griffin eMagRes, p. 339–352, 2019, ISBN: 9780470034590. @incollection{Tan2019d, title = {Pulsed Dynamic Nuclear Polarization}, author = {Kong Ooi Tan and Sudheer Jawla and Richard J Temkin and Robert G Griffin}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470034590.emrstm1551 https://doi.org/10.1002/9780470034590.emrstm1551}, doi = {10.1002/9780470034590.emrstm1551}, isbn = {9780470034590}, year = {2019}, date = {2019-09-01}, booktitle = {eMagRes}, pages = {339--352}, series = {Major Reference Works}, abstract = {Abstract In the last two decades continuous-wave (CW) microwave irradiation obtained from gyrotron microwave sources has been utilized extensively in the development and applications of new experimental approaches to high frequency dynamic nuclear polarization (DNP). Despite the abundant successes of this approach, it is well established experimentally and understood theoretically that at higher magnetic fields, where the resolution of the NMR spectra is optimal, the enhancement factors in CW DNP experiments decrease. Potentially this issue can be mitigated by using time domain or pulsed DNP techniques, which theoretically have field-independent enhancement factors. In this contribution, we discuss the pulsed DNP experiments that have been developed to date, along with the theory and the applicability of the sequences. As we will see pulsed techniques are fundamentally different from the CW-DNP methodology and require a different array of instrumentation, spin physics, and radicals. Hence, in addition to the underlying theory, we discuss the specifications of the microwave sources, DNP probes, and optimal radicals for pulsed DNP. The review ends with a summary of the current and future applications of pulsed DNP and conjectures as to the development of the pulsed methods for experiments at increasingly higher magnetic fields.}, keywords = {}, pubstate = {published}, tppubtype = {incollection} } Abstract In the last two decades continuous-wave (CW) microwave irradiation obtained from gyrotron microwave sources has been utilized extensively in the development and applications of new experimental approaches to high frequency dynamic nuclear polarization (DNP). Despite the abundant successes of this approach, it is well established experimentally and understood theoretically that at higher magnetic fields, where the resolution of the NMR spectra is optimal, the enhancement factors in CW DNP experiments decrease. Potentially this issue can be mitigated by using time domain or pulsed DNP techniques, which theoretically have field-independent enhancement factors. In this contribution, we discuss the pulsed DNP experiments that have been developed to date, along with the theory and the applicability of the sequences. As we will see pulsed techniques are fundamentally different from the CW-DNP methodology and require a different array of instrumentation, spin physics, and radicals. Hence, in addition to the underlying theory, we discuss the specifications of the microwave sources, DNP probes, and optimal radicals for pulsed DNP. The review ends with a summary of the current and future applications of pulsed DNP and conjectures as to the development of the pulsed methods for experiments at increasingly higher magnetic fields. |
Three-spin solid effect and the spin diffusion barrier in amorphous solids Article de journal Kong Ooi Tan; Michael Mardini; Chen Yang; Jan Henrik Ardenkjær-Larsen; Robert Guy Griffin Science Advances, 5 (7), p. eaax2743, 2019, ISSN: 2375-2548. @article{Tan2019a, title = {Three-spin solid effect and the spin diffusion barrier in amorphous solids}, author = {Kong Ooi Tan and Michael Mardini and Chen Yang and Jan Henrik Ardenkj{\ae}r-Larsen and Robert Guy Griffin}, url = {http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aax2743 http://doi.org/10.1126/sciadv.aax2743 https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aax2743}, doi = {10.1126/sciadv.aax2743}, issn = {2375-2548}, year = {2019}, date = {2019-07-01}, journal = {Science Advances}, volume = {5}, number = {7}, pages = {eaax2743}, abstract = {Dynamic nuclear polarization (DNP) has evolved as the method of choice to enhance NMR signal intensities and to address a variety of otherwise inaccessible chemical, biological and physical questions. Despite its success, there is no detailed understanding of how the large electron polarization is transferred to the surrounding nuclei or where these nuclei are located relative to the polarizing agent. To address these questions we perform an analysis of the three-spin solid effect, and show that it is exquisitely sensitive to the electron-nuclear distances. We exploit this feature and determine that the size of the spin diffusion barrier surrounding the trityl radical in a glassy glycerol\textendashwater matrix is <6 r{A}, and that the protons involved in the initial transfer step are on the trityl molecule. 1 H ENDOR experiments indicate that polarization is then transferred in a second step to glycerol molecules in intimate contact with the trityl.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic nuclear polarization (DNP) has evolved as the method of choice to enhance NMR signal intensities and to address a variety of otherwise inaccessible chemical, biological and physical questions. Despite its success, there is no detailed understanding of how the large electron polarization is transferred to the surrounding nuclei or where these nuclei are located relative to the polarizing agent. To address these questions we perform an analysis of the three-spin solid effect, and show that it is exquisitely sensitive to the electron-nuclear distances. We exploit this feature and determine that the size of the spin diffusion barrier surrounding the trityl radical in a glassy glycerol–water matrix is <6 Å, and that the protons involved in the initial transfer step are on the trityl molecule. 1 H ENDOR experiments indicate that polarization is then transferred in a second step to glycerol molecules in intimate contact with the trityl. |
Time-optimized pulsed dynamic nuclear polarization Article de journal Kong Ooi Tan; Chen Yang; Ralph T Weber; Guinevere Mathies; Robert G Griffin Science Advances, 5 (1), p. eaav6909, 2019, ISSN: 2375-2548. @article{Kong_Ooi_Tan52857775, title = {Time-optimized pulsed dynamic nuclear polarization}, author = {Kong Ooi Tan and Chen Yang and Ralph T Weber and Guinevere Mathies and Robert G Griffin}, url = {http://doi.org/10.1126/sciadv.aav6909 http://advances.sciencemag.org/ http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aav6909}, doi = {10.1126/sciadv.aav6909}, issn = {2375-2548}, year = {2019}, date = {2019-01-01}, journal = {Science Advances}, volume = {5}, number = {1}, pages = {eaav6909}, abstract = {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 $tau$ p spaced with delays d . A particularly robust DNP condition using a period $tau$ m = $tau$ p + d set to $sim$1.25 times the Larmor period $tau$ Larmor is investigated which is a time-optimized pulsed DNP sequence (TOP-DNP). At 0.35 T, we obtained an enhancement of $sim$200 using TOP-DNP compared to $sim$172 with nuclear spin orientation via electron spin locking (NOVEL), a commonly used pulsed DNP sequence, while using only $sim$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.}, keywords = {}, pubstate = {published}, tppubtype = {article} } 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 $tau$ p spaced with delays d . A particularly robust DNP condition using a period $tau$ m = $tau$ p + d set to $sim$1.25 times the Larmor period $tau$ Larmor is investigated which is a time-optimized pulsed DNP sequence (TOP-DNP). At 0.35 T, we obtained an enhancement of $sim$200 using TOP-DNP compared to $sim$172 with nuclear spin orientation via electron spin locking (NOVEL), a commonly used pulsed DNP sequence, while using only $sim$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. |
2018 |
Efficient low-power TOBSY sequences for fast MAS Article de journal Kong Ooi Tan; Vipin Agarwal; Nils-Alexander Lakomek; Susanne Penzel; Beat H Meier; Matthias Ernst Solid State Nuclear Magnetic Resonance, 89 (October), p. 27–34, 2018, ISSN: 09262040. @article{Tan2017, title = {Efficient low-power TOBSY sequences for fast MAS}, author = {Kong Ooi Tan and Vipin Agarwal and Nils-Alexander Lakomek and Susanne Penzel and Beat H Meier and Matthias Ernst}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0926204017301339 https://linkinghub.elsevier.com/retrieve/pii/S0926204017301339}, doi = {10.1016/j.ssnmr.2017.11.003}, issn = {09262040}, year = {2018}, date = {2018-02-01}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {89}, number = {October}, pages = {27--34}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Metal-free class Ie ribonucleotide reductase from pathogens initiates catalysis with a tyrosine-derived dihydroxyphenylalanine radical Article de journal Elizabeth J Blaesi; Gavin M Palowitch; Kai Hu; Amelia J Kim; Hannah R Rose; Rahul Alapati; Marshall G Lougee; Hee Jong Kim; Alexander T Taguchi; Kong Ooi Tan; others Proceedings of the National Academy of Sciences, 115 (40), p. 10022–10027, 2018. @article{blaesi2018metal, title = {Metal-free class Ie ribonucleotide reductase from pathogens initiates catalysis with a tyrosine-derived dihydroxyphenylalanine radical}, author = {Elizabeth J Blaesi and Gavin M Palowitch and Kai Hu and Amelia J Kim and Hannah R Rose and Rahul Alapati and Marshall G Lougee and Hee Jong Kim and Alexander T Taguchi and Kong Ooi Tan and others}, year = {2018}, date = {2018-01-01}, journal = {Proceedings of the National Academy of Sciences}, volume = {115}, number = {40}, pages = {10022\textendash10027}, publisher = {National Academy of Sciences}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2017 |
Peptide and protein dynamics and low-temperature/DNP magic angle spinning NMR Article de journal Qing Zhe Ni; Evgeny Markhasin; Thach V Can; Björn Corzilius; Kong Ooi Tan; Alexander B Barnes; Eugenio Daviso; Yongchao Su; Judith Herzfeld; Robert G Griffin The Journal of Physical Chemistry B, 121 (19), p. 4997–5006, 2017. @article{ni2017peptide, title = {Peptide and protein dynamics and low-temperature/DNP magic angle spinning NMR}, author = {Qing Zhe Ni and Evgeny Markhasin and Thach V Can and Björn Corzilius and Kong Ooi Tan and Alexander B Barnes and Eugenio Daviso and Yongchao Su and Judith Herzfeld and Robert G Griffin}, year = {2017}, date = {2017-01-01}, journal = {The Journal of Physical Chemistry B}, volume = {121}, number = {19}, pages = {4997\textendash5006}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Optimizing symmetry-based recoupling sequences in solid-state NMR by pulse-transient compensation and asynchronous implementation Article de journal Johannes Hellwagner; Kshama Sharma; Kong Ooi Tan; Johannes J Wittmann; Beat H Meier; Perunthiruthy K Madhu; Matthias Ernst The Journal of chemical physics, 146 (24), p. 244202, 2017. @article{hellwagner2017optimizing, title = {Optimizing symmetry-based recoupling sequences in solid-state NMR by pulse-transient compensation and asynchronous implementation}, author = {Johannes Hellwagner and Kshama Sharma and Kong Ooi Tan and Johannes J Wittmann and Beat H Meier and Perunthiruthy K Madhu and Matthias Ernst}, year = {2017}, date = {2017-01-01}, journal = {The Journal of chemical physics}, volume = {146}, number = {24}, pages = {244202}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2016 |
Theoretical description of RESPIRATION-CP Article de journal Anders B Nielsen; Kong Ooi Tan; Ravi Shankar; Susanne Penzel; Riccardo Cadalbert; Ago Samoson; Beat H Meier; Matthias Ernst Chemical Physics Letters, 645 , p. 150–156, 2016. @article{nielsen2016theoretical, title = {Theoretical description of RESPIRATION-CP}, author = {Anders B Nielsen and Kong Ooi Tan and Ravi Shankar and Susanne Penzel and Riccardo Cadalbert and Ago Samoson and Beat H Meier and Matthias Ernst}, year = {2016}, date = {2016-01-01}, journal = {Chemical Physics Letters}, volume = {645}, pages = {150\textendash156}, publisher = {North-Holland}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Improved transfer efficiencies in radio-frequency-driven recoupling solid-state NMR by adiabatic sweep through the dipolar recoupling condition Article de journal Lasse A Straasø; Ravi Shankar; Kong Ooi Tan; Johannes Hellwagner; Beat H Meier; Michael Ryan Hansen; Niels Chr Nielsen; Thomas Vosegaard; Matthias Ernst; Anders B Nielsen The Journal of chemical physics, 145 (3), p. 034201, 2016. @article{straaso2016improved, title = {Improved transfer efficiencies in radio-frequency-driven recoupling solid-state NMR by adiabatic sweep through the dipolar recoupling condition}, author = {Lasse A Straas\o and Ravi Shankar and Kong Ooi Tan and Johannes Hellwagner and Beat H Meier and Michael Ryan Hansen and Niels Chr Nielsen and Thomas Vosegaard and Matthias Ernst and Anders B Nielsen}, year = {2016}, date = {2016-01-01}, journal = {The Journal of chemical physics}, volume = {145}, number = {3}, pages = {034201}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance Article de journal Kong Ooi Tan; Vipin Agarwal; Beat H Meier; Matthias Ernst The Journal of chemical physics, 145 (9), p. 094201, 2016. @article{tan2016generalized, title = {A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance}, author = {Kong Ooi Tan and Vipin Agarwal and Beat H Meier and Matthias Ernst}, year = {2016}, date = {2016-01-01}, journal = {The Journal of chemical physics}, volume = {145}, number = {9}, pages = {094201}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2015 |
Asynchronous symmetry-based sequences for homonuclear dipolar recoupling in solid-state nuclear magnetic resonance Article de journal Kong Ooi Tan; M Rajeswari; PK Madhu; Matthias Ernst The Journal of chemical physics, 142 (6), p. 02B605_1, 2015. @article{tan2015asynchronous, title = {Asynchronous symmetry-based sequences for homonuclear dipolar recoupling in solid-state nuclear magnetic resonance}, author = {Kong Ooi Tan and M Rajeswari and PK Madhu and Matthias Ernst}, year = {2015}, date = {2015-01-01}, journal = {The Journal of chemical physics}, volume = {142}, number = {6}, pages = {02B605_1}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2014 |
Improved decoupling during symmetry-based C9-TOBSY sequences Article de journal Kong Ooi Tan; Ingo Scholz; Jacco D van Beek; Beat H Meier; Matthias Ernst Journal of Magnetic Resonance, 239 , p. 61–68, 2014. @article{tan2014improved, title = {Improved decoupling during symmetry-based C9-TOBSY sequences}, author = {Kong Ooi Tan and Ingo Scholz and Jacco D van Beek and Beat H Meier and Matthias Ernst}, year = {2014}, date = {2014-01-01}, journal = {Journal of Magnetic Resonance}, volume = {239}, pages = {61\textendash68}, publisher = {Academic Press}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Broad-band DREAM recoupling sequence Article de journal Kong Ooi Tan; Anders B Nielsen; Beat H Meier; Matthias Ernst The journal of physical chemistry letters, 5 (19), p. 3366–3372, 2014. @article{tan2014broad, title = {Broad-band DREAM recoupling sequence}, author = {Kong Ooi Tan and Anders B Nielsen and Beat H Meier and Matthias Ernst}, year = {2014}, date = {2014-01-01}, journal = {The journal of physical chemistry letters}, volume = {5}, number = {19}, pages = {3366\textendash3372}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2013 |
Selective inversion of 1H resonances in solid-state nuclear magnetic resonance: Use of double-DANTE pulse sequence Article de journal Venus Singh Mithu; Kong Ooi Tan; PK Madhu Journal of Magnetic Resonance, 237 , p. 11–16, 2013. @article{mithu2013selective, title = {Selective inversion of 1H resonances in solid-state nuclear magnetic resonance: Use of double-DANTE pulse sequence}, author = {Venus Singh Mithu and Kong Ooi Tan and PK Madhu}, year = {2013}, date = {2013-01-01}, journal = {Journal of Magnetic Resonance}, volume = {237}, pages = {11\textendash16}, publisher = {Academic Press}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
