Compact Electron Paramagnetic Resonance on a Chip Spectrometer Using a Single Sided Permanent Magnet.

Area of Science:

• Spectroscopy
• Materials Science
• Physical Chemistry

Background:

• Conventional Electron Paramagnetic Resonance (EPR) spectroscopy requires large equipment, limiting its use in situ or operando.
• Paramagnetic states provide insights into material properties, but accessibility for real-time experiments is challenging.

Purpose of the Study:

• To develop a portable EPR sensor for in situ and operando measurements.
• To overcome the spatial limitations of traditional EPR setups.
• To enable EPR analysis directly within various experimental environments.

Main Methods:

• Integration of EPR-on-a-Chip (EPRoC) with a single-sided permanent magnet.
• Utilizing an array of 14 voltage-controlled oscillator (VCO) coils operating at 7 GHz.
• Spatial mapping of magnetic fields using crystalline BDPA and thin film a-Si.
• Performing EPR experiments on tempol in a glycerol-water solution.

Main Results:

• Demonstrated a portable EPR sensor capable of in situ and operando measurements.
• Achieved 2D spatial magnetic field mapping with 50 μm resolution over a 1.5 mm × 5 mm region.
• Determined magnetic field intensity (254.69 mT) and homogeneity (700 ppm).
• Successfully measured molecular tumbling correlation time and established spin quantification for tempol.

Conclusions:

• The developed portable EPR sensor offers a versatile solution for advanced material characterization.
• This miniaturized spectrometer facilitates EPR analysis directly within challenging sample environments.
• The device enables real-time monitoring of chemical and physical properties through EPR spectroscopy.