A low-cost implementation of EPR detection in a dissolution DNP setup.

Area of Science:

• Magnetic Resonance Spectroscopy
• Physical Chemistry
• Chemical Physics

Background:

• Dynamic Nuclear Polarization (DNP) enhances nuclear spin polarization.
• Low-temperature DNP is crucial for certain radical studies.
• Electron Paramagnetic Resonance (EPR) detects unpaired electrons.

Purpose of the Study:

• To integrate Electron Paramagnetic Resonance (EPR) detection into a low-temperature dissolution Dynamic Nuclear Polarization (DNP) setup.
• To demonstrate the measurement of longitudinal magnetization changes in free radicals using modulated microwave fields.
• To enable advanced EPR experiments like pump-probe and time-resolved measurements within the DNP framework.

Main Methods:

• Utilizing a coil oriented parallel to the static magnetic field for EPR detection.
• Employing amplitude or frequency modulated microwave (mw) fields for resonant irradiation.
• Implementing pulsed EPR techniques for pump-probe experiments (e.g., saturation-recovery, electron-electron double resonance).

Main Results:

• Absorption EPR spectra obtained via amplitude modulation of the mw field.
• First derivative EPR spectra obtained via frequency modulation of the mw field.
• Time-resolved monitoring of magnetization transients during amplitude modulation.

Conclusions:

• The presented setup successfully integrates EPR detection with low-temperature dissolution DNP.
• This approach allows for versatile EPR measurements, including spectral acquisition and time-resolved studies.
• Demonstrated utility with trityl radical and TEMPO, common in DNP research.