Long-lived nuclear spin states in monodeuterated methyl groups

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Quantum Information Science
• Physical Chemistry

Background:

• Nuclear singlet order is a quantum spin state with potential applications in NMR spectroscopy.
• Achieving long-lived singlet order is challenging due to rapid relaxation processes.
• Monodeuterated methyl groups (CH2D) in chiral environments offer unique possibilities for spin manipulation.

Purpose of the Study:

• To experimentally demonstrate the accessibility of long-lived nuclear singlet order in monodeuterated methyl groups.
• To investigate the factors influencing the lifetime of this singlet order.
• To explore the potential of this phenomenon for NMR applications.

Main Methods:

• Utilizing Nuclear Magnetic Resonance (NMR) techniques to prepare and detect nuclear singlet order.
• Employing monodeuterated methyl groups in a chiral molecule (N-CH2D-2-methylpiperidine) as a model system.
• Conducting experiments across a range of temperatures, solvents, and magnetic fields to study relaxation dynamics.

Main Results:

• Successfully accessed long-lived nuclear singlet order in the CH2D groups.
• Observed a singlet relaxation time constant (TS) to longitudinal relaxation time constant (T1) ratio of 3.1 ± 0.1.
• Achieved singlet order lifetimes approaching one minute under specific experimental conditions.

Conclusions:

• Long-lived nuclear singlet order is accessible in monodeuterated methyl groups within chiral environments.
• The observed TS/T1 ratio suggests efficient preservation of singlet order.
• A modified CH2D geometry model is proposed to explain the observed relaxation behavior and long lifetimes.