Combined k-space q-space pulsed ESR imaging: mapping of restricted diffusion in (FA)(2)PF(6)

Area of Science:

• Solid-state physics
• Materials science
• Organic electronics

Background:

• Quasi-one-dimensional organic conductors exhibit unique charge transport properties.
• Understanding charge carrier dynamics in these materials is crucial for developing advanced electronic devices.
• Selective damage can be used to probe confinement effects on charge transport.

Purpose of the Study:

• To investigate the effect of selective damage on charge carrier motion in (FA)(2)PF(6) crystals.
• To probe local charge carrier spin dynamics in restricted environments.
• To demonstrate the application of pulsed ESR imaging techniques for studying confined charge transport.

Main Methods:

• Selective crystal damage using a focused helium ion beam and a slitted mask.
• Pulsed electron spin resonance (ESR) density-weighted imaging to identify damaged and undamaged regions.
• Combined k-space and q-space pulsed ESR imaging to analyze local spin dynamics.
• Analysis of pulsed gradient spin echo (PGSE) "diffusive diffraction" patterns.

Main Results:

• Helium ion irradiation created regions with an absent ESR signal, indicating damage.
• Charge carrier motion was confined to the undamaged sections of the crystal.
• Local spin dynamics in restricted areas were successfully probed using advanced ESR techniques.
• Observed "diffusive diffraction" patterns were consistent with density imaging results.

Conclusions:

• Selective damage effectively restricts one-dimensional charge carrier motion in (FA)(2)PF(6) crystals.
• Pulsed ESR imaging is a powerful tool for visualizing charge carrier confinement.
• The study provides insights into local spin dynamics under spatial restriction, relevant for organic conductor research.