Nonlinearity Meets Complexity: Radio-Frequency Masers And Dynamic Nuclear Polarization (Dnp)

22 May 2023

Job Information

Organisation/Company

Ecole Normale Supérieure

Department

Chemistry department

Research Field

Chemistry » Physical chemistry

Researcher Profile

Recognised Researcher (R2)

Country

France

Application Deadline

1 Sep 2023 - 23:59 (Europe/Paris)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

37.5

Offer Starting Date

1 Sep 2023

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

NMR spectroscopy is a powerful and versatile method that is used worldwide in many fields in research, health and industry. It can provide quantitative information on structures and dynamics at the molecular level. However, the major drawback of NMR is its intrinsic low sensitivity due to the low nuclear spin polarization - the relative population difference between neighboring energy levels - even at high magnetic fields (~ 5x10-5 for 1H nuclei at 14.1 T and ambient temperature).

Dynamic nuclear polarization (DNP) techniques are capable to drive the nuclear spins out of equilibrium to a hyperpolarized state with polarizations up to 80-90%, by transferring the high polarization of paramagnetic impurities (electron spin polarization is ~100% at 1.2 K) to the nuclear spins through hyperfine or super-hyperfine coupling. One of the intriguing aspects of NMR at such very high polarizations is the occurrence of nonlinear effects related to the associated large magnetization. The strong coupling between the nuclear magnetization in the sample with the NMR detection circuit gives rise to so- called “radiation damping” (RD) effects where the magnetization-dependent radiofrequency (rf) field generated by the coil and acts back on the magnetization to induce a precession of the latter towards its equilibrium, inducing « maser » pulses. Under certain experimental conditions, the NMR signal exhibits sustained maser pulses that persist for several minutes or hours, whilst typical solid state NMR signals disappear in less than a millisecond. In these unconventional conditions, phase coherence induced by radiation damping allows long range (weak) dipolar effects to be observed, which is unexpected in such conditions.

During this project, we will investigate the relations between the nonlinearities of the spin dynamics caused by radiation feedback and dipolar field effects, on the one hand, and DNP, on the other hand. Theoretical and numerical tools will be developed to investigate these complex systems. Experimental aspects will be explored to better understand the phenomena involved and the dynamics of the magnetization. An electronic feedback sysem to control radiation damping on a 6,7 T polarizer, but also in solution, on a conventional NMR spectrometer, will be implemented an developed to investigate the magnetization dynamics.

References

1- E. Weber, D. Kurzbach, D. Abergel Phys. Chem. Chem. Phys. , 2019, 21 , 21278-21286 (DOI : 10.1039/C9CP03334C)

2- V. Thalakottoor, D. Abergel Phys. Chem. Chem. Phys. , 2023, 25 , 10392-10404 (DOI : doi.org/10.1039/D2CP05696H)

Requirements

Research Field

Physics » Chemical physics

Education Level

PhD or equivalent

Research Field

Physics » Chemical physics

Education Level

Master Degree or equivalent

Skills/Qualifications

This project is intended either for a postdoctoral researcher or a PhD candidate.

Interested postdoctoral candidates should have a PhD in physical sciences (Physics or Chemistry), with strong experience in fundamental aspects of NMR. Previous training in experimental physics and instrumentation, including hands-on experience with radiofrequency instrumentation are welcome.

Highly motivated PhD candidates should have a strong background in fundamental physical sciences, with at lest some knowledge in NMR. Also, training in experimental physics and instrumentation is recommended, as well as in scientific computing.

Languages

ENGLISH

Level

Excellent

Additional Information

Selection process

Please send a CV, a motivation letter and two letters of recommendation.

Selected candidates will be interviewed remotely through visioconference.

Work Location(s)

Number of offers available

1

Company/Institute

Ecole Normale Supérieure

Country

France

City

Paris

Postal Code

75005

Street

24 rue Lhomond

Geofield

Where to apply

E-mail

[email protected]

Contact

State/Province

Ile de France

City

Paris

Website

https: // www. ens.psl.eu/en/ens/universite-psl

Street

24 rue Lhomond

Postal Code

75230

E-Mail

[email protected]

STATUS: EXPIRED