Cross polarization from (1)H to quadrupolar (6)Li nuclei for dissolution DNP

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
• Quantum information science
• Materials science

Background:

• Dynamic Nuclear Polarization (DNP) significantly enhances NMR signal sensitivity.
• Efficient polarization of quadrupolar nuclei like lithium-6 (⁶Li) is crucial for various applications.
• Current methods for polarizing ⁶Li nuclei can be time-consuming or less efficient.

Purpose of the Study:

• To develop a more efficient method for polarizing ⁶Li nuclei.
• To investigate the combination of proton-electron cross-polarization with dynamic nuclear polarization (DNP) for enhanced ⁶Li polarization.
• To design and implement a specialized probe for simultaneous proton and ⁶Li measurements.

Main Methods:

• Utilized dynamic nuclear polarization (DNP) of protons at 1.2 K and 6.7 T with TEMPOL as the polarizing agent.
• Implemented cross-polarization from polarized protons to quadrupolar ⁶Li nuclei.
• Employed rapid dissolution techniques post-polarization.
• Designed and used a double resonance ¹H-⁶Li probe equipped for Longitudinally Detected Electron Spin Resonance (LDESR).

Main Results:

• Achieved a higher nuclear spin polarization for ⁶Li (P(⁶Li)) compared to direct ⁶Li DNP without cross-polarization.
• Demonstrated that the combined cross-polarization and DNP method significantly reduces polarization time.
• Successfully designed and tested a specialized probe enabling simultaneous measurements.

Conclusions:

• The combination of proton-electron cross-polarization and DNP offers a superior method for polarizing ⁶Li nuclei.
• This technique provides enhanced polarization in shorter timescales, increasing experimental efficiency.
• The developed double resonance probe facilitates advanced NMR studies involving coupled proton and ⁶Li spin systems.