Direct conversion of EPR dipolar time evolution data to distance distributions.

Area of Science:

• Electron paramagnetic resonance spectroscopy
• Magnetic resonance techniques
• Spin dynamics in disordered systems

Background:

• Dipole-dipole couplings between electron spins yield insights into spin distribution.
• Analyzing these couplings in disordered systems is crucial for understanding material properties.
• Existing methods face challenges in accurately quantifying radial distribution functions.

Purpose of the Study:

• To develop and validate a method for determining radial distribution functions from electron spin echo envelope modulations.
• To investigate the applicability of shell factorization for analyzing dipolar time evolution data.
• To assess the impact of neglecting orientational selection on distance distribution accuracy.

Main Methods:

• Utilizing shallow electron spin echo envelope modulations.
• Applying shell factorization by averaging orientational data over spherical shells.
• Separating dipolar time evolution data into linear and nonlinear contributions.
• Direct conversion of linear contribution to radial distribution function.

Main Results:

• Shell factorization accurately simulates dipolar time evolution for arbitrary radial distribution functions.
• A linear superposition of shell signals is sufficient for distances below 5 nm.
• The method shows good agreement with force-field computations for biradicals.
• Neglecting orientational selection does not significantly distort determined distance distributions.

Conclusions:

• Shell factorization provides a robust method for extracting radial distribution functions from spin dynamics data.
• The approach is effective for disordered systems with negligible angular correlations.
• This technique offers a reliable way to characterize spin distribution in systems like biradicals.