Electron paramagnetic relaxation enhancement produced on T₁ by anisotropic g-tensors in rigid systems

Abstract

Paramagnetic relaxation enhancement is a fundamental molecular physical phenomenon, manifested as an acceleration of the relaxation times of a slowly relaxing spin S ^slow due to the magnetic interaction, dipolar or exchange, with a fast relaxing spin S ^fast. Here, we examine the general case of the enhancement of due to a fast relaxer S ^fast with rhombic g-tensor. Using the formalism of Kubo and Tomita we derive the following analytical expression for the dipolar effect on :

where , , i.e. B is the g-rhombicity factor, and f ₀, f ₁, f ₂ and f ₃ are angular functions of the angles θ, ϕ and the Euler angles (β, γ).

Keywords:

• T ₁
• Dipolar
• EPR spectroscopy
• g-Tensor
• Anisotropy
• Distance
• Saturation