Exchange coupling-assisted ¹³C dynamic nuclear polarization in microdiamonds at 14 T

Area of Science:

• Solid-state physics
• Quantum chemistry
• Materials science

Background:

• Nitrogen substitution defects (P1 centers) in diamonds are crucial for quantum applications.
• High-pressure, high-temperature (HPHT) diamonds offer unique material properties.
• Dynamic Nuclear Polarization (DNP) enhances nuclear spin polarization for improved NMR sensitivity.

Purpose of the Study:

• Investigate electron spin polarization transfer from P1 centers to ¹³C nuclear spins in HPHT diamonds.
• Evaluate the potential of P1 centers as a source for DNP hyperpolarization and contrast enhancement.
• Refine the model for clustered P1 centers in HPHT diamonds for DNP applications.

Main Methods:

• Frequency-stepped DNP profile measurements under magic angle spinning (MAS) and static conditions.
• Utilized a frequency-tunable gyrotron and a 14.1 T superconducting NMR magnet.
• Developed and applied computational models to interpret experimental DNP data.

Main Results:

• Achieved up to 700-fold ¹³C signal enhancements at room temperature (MAS and static).
• Observed 130-fold enhancements between 35 K and 100 K.
• Identified dominant role of P1 clusters with >100 MHz inter-P1 couplings for efficient DNP.

Conclusions:

• P1 centers in HPHT diamonds are effective sources for ¹³C DNP hyperpolarization at high magnetic fields.
• Exchange coupling within P1 clusters is critical for achieving high DNP enhancements.
• The study provides a refined model for DNP via P1 centers, crucial for advancing NMR spectroscopy and quantum technologies.