Department of Physics, City College of New York, City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
Proc Natl Acad Sci U S A. 2011 Dec 6;108(49):19510-5. doi: 10.1073/pnas.1108702108. Epub 2011 Nov 18.
We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids. Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems.
我们利用光法拉第旋转（OFR）在高磁场范围内对顺磁样品流体中的核自旋进行实时探测。对比 OFR 检测到的 NMR 谱揭示了相对信号幅度与流体Verdet 常数之间的相关性，我们将其解释为探针光束与样品光学跃迁之间的失谐变化的表现。对化学位移分辨的光探测光谱的分析允许我们对不同化学位置的质子以及其他低磁旋比核（包括碳、氟和磷）的超精细耦合常数的相对幅度进行约束。通过考虑一个模型二元混合物，我们观察到光学响应对相对浓度的复杂依赖性，这表明该方法对溶剂-溶质动力学的敏感性与感应 NMR 中已知的方法互补。这些实验的扩展可能会在溶剂抑制方案、溶液中金属蛋白的灵敏度增强 NMR、溶剂-溶质相互作用的研究或顺磁系统中分子轨道的表征方面找到应用。
