Gadolinium Spin Decoherence Mechanisms at High Magnetic Fields.

Area of Science:

• Biophysics
• Magnetic Resonance Spectroscopy

Background:

• Spin-7/2 Gd³⁺ ions are valuable for high-field EPR protein studies due to favorable relaxation and spectral properties.
• However, high-field relaxation and decoherence in high-spin systems like Gd³⁺ are not well understood.

Purpose of the Study:

• To investigate spin-lattice (T₁) and phase memory (T_M) relaxation times at 8.6 T (240 GHz) for Gd³⁺ systems.
• To develop a comprehensive model for high-field, high-spin decoherence considering electron spin concentration and temperature.

Main Methods:

• Experimental measurement of T₁ and T_M relaxation times at 8.6 T.
• Development of a theoretical model incorporating four primary decoherence mechanisms.

Main Results:

• Reported T₁ and T_M relaxation times at 8.6 T.
• Presented a novel model for high-field, high-spin decoherence.
• Identified four key decoherence drivers: spin flip-flops, direct and indirect T₁-driven flips, and nuclear spin flip-flops.

Conclusions:

• The developed model provides mechanistic insight into Gd³⁺ decoherence at high fields.
• This understanding can guide the design of experiments using Gd³⁺ as spin probes or relaxivity agents.
• The findings enable the measurement of average interspin distances up to 17 nm.