Preparation of Nuclear Spin Singlet States using Spin-Lock Induced Crossing

TL;DR

This paper presents a new pulse sequence technique called SLIC for efficiently creating long-lived nuclear spin singlet states in molecules, enabling improved measurements of molecular parameters and potential applications in quantum information.

Contribution

The paper introduces the SLIC method, a novel pulse sequence that induces spin-lock crossing to generate nuclear spin singlet states more efficiently than previous techniques.

Findings

Successfully produced long-lived singlet states in a peptide molecule.

Demonstrated improved efficiency of SLIC over existing methods.

Measured J-couplings and singlet lifetimes using SLIC.

Abstract

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet/singlet polarization transfer and singlet state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly-coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O, and by using SLIC to measure the J-couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly-equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet/singlet polarization transfer occurs on the same timescale as spin-lattice relaxation.