Affiliation:
1. National Center for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan Hubei 430071 China
2. University of Chinese Academy of Sciences Beijing 100049 China
3. Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan Hubei 430074 China
Abstract
AbstractAdditional phase modulation (APM) is proposed to generally enhance the theoretical efficiency of homonuclear double‐quantum (DQ) recoupling in solid‐state NMR. APM applies an additional phase list to DQ recoupling in steps of an entire block. The sine‐based phase list can enhance the theoretical efficiency by 15–30 %, from 0.52 to 0.68 (non‐γ‐encoded recoupling) or from 0.73 to 0.84 (γ‐encoded recoupling), with doubled recoupling time. The genetic‐algorithm (GA) optimized APM can adiabatically enhance the efficiency to ∼1.0 at longer times. The concept of APM has been tested on SPR‐51, BaBa, and SPR‐31, which represent γ‐encoded recoupling, non‐γ‐encoded recoupling, and another kind beyond the former two, respectively. Simulations reveal that enhancements from APM are due to the activation of more crystallites in the powder. Experiments on 2,3‐13C labeled alanine are used to validate the APM recoupling. This new concept shall shed light on developing more efficient homonuclear recoupling methods.
Funder
National Natural Science Foundation of China
Chinese Academy of Sciences
Subject
Physical and Theoretical Chemistry,Atomic and Molecular Physics, and Optics