Intermolecular multiple quantum coherences at high magnetic field: the nonlinear regime

Area of Science:

• Magnetic Resonance Spectroscopy
• Quantum Coherence Dynamics

Background:

• Intermolecular multiple quantum coherences (IMQCs) are crucial for understanding spin interactions.
• The nonlinear regime, where system evolution exceeds dipolar field timescales (τd), presents unique challenges for studying IMQCs.

Purpose of the Study:

• To explore the evolution of IMQCs in the nonlinear regime at various magnetic field strengths (9.4, 14.1, and 17.6 T).
• To validate a numerical method for magnetization evolution calculations against experimental data.

Main Methods:

• Experimental measurements of IMQC evolution at different magnetic field strengths.
• Numerical simulations using a Fourier analysis-based method for magnetization evolution, incorporating dipolar field, relaxation, and diffusion.
• Application of a correlated two-dimensional spectroscopy sequence with asymmetric z-gradient echo detection.

Main Results:

• Experimental signals exhibited the predicted Bessel function dependence on evolution time, including zeros and sign changes.
• Increased magnetic field strengths led to faster signal evolution due to enhanced equilibrium magnetization.
• Numerical simulations demonstrated good agreement with experimental results across different magnetic fields and spatial modulation rates.

Conclusions:

• The study confirms the theoretical predictions for IMQC evolution in the nonlinear regime.
• The developed numerical method accurately models magnetization dynamics under complex conditions.
• The findings provide insights into spin dynamics in interacting spin systems within strong magnetic fields.