F-cluster: Reaction-induced spin correlation in multi-radical systems

Area of Science:

• Chemical Physics
• Theoretical Chemistry
• Spin Chemistry

Background:

• Radical pair (F-pair) recombination is crucial for spin-driven magnetic field effects.
• Spin correlation in radical systems dictates reaction outcomes.
• Generalizing F-pairs to larger radical clusters (F-clusters) is needed for complex systems.

Purpose of the Study:

• To theoretically analyze spin-selective recombination in radical clusters (n ≥ 3).
• To investigate spin correlation arising from random radical encounters.
• To explore magnetic field effects originating from these F-clusters.

Main Methods:

• Theoretical analysis using spin density operator expansion.
• Evaluation of survival probabilities and spin correlation.
• Application of Haberkorn recombination operator and singlet-triplet dephasing.

Main Results:

• Steady-state spin density operator is independent of recombination network details for irreducible clusters.
• Surviving radical pairs exhibit triplet polarization, irrespective of reaction.
• Steady state is insensitive to singlet-triplet dephasing, but kinetics and smaller clusters depend on it.

Conclusions:

• Spin-selective recombination in F-clusters generates spin polarization and magnetic field effects.
• The theoretical framework extends to radical pair scavenging and larger systems.
• Understanding these spin dynamics is key for controlling radical reaction pathways.