基于原子磁力计的超低场激光探测NMR研究

The state of the art of the NMR and MRI devices has several problems, such as low efficiency radio-frequency coil probes, seriously dependent on the superconducting magnet, unable to analyze samples containing ferromagnetic elements. This project employs the method of laser-detected NMR, using an atomic magnetometer as the NMR probe for magnetic field,not only solved above problems, but also has the advantages of small size and low power consumption, making it possible to realize low cost and portable NMR and MRI devices. Present laser-detected NMR uses spin-exchange relaxation free (SERF) magnetometer mostly, whose high working temperature and being spatially near from the NMR samples, would change the samples' relaxation characteristics and large polarization loss due to the slow sample delivering between the polarization and detection regions. Aiming to solve the two problems, our project uses the homebuilt nonlinear magneto-optical rotation (NMOR) magnetometer working near room temperature, through a specially designed adiabatic sample tranporting equipment and coresponding controlling pulse sequence, minishing the polarization loss in the sample transmit process due to the remotely settled polarization magnet and magnetometer probe and developing more sensitive laser-detected NMR spectrometer. With 13C labelled ethanol as the sample, high resolution J-coupling spectroscopy will be obtained. The laser-detected NMR plan described here, can imporve the resolution of ultralow field even zero field NMR, obtaining long range J-coupling spectra in absence of Zeeman interaction and thus the informations on the fine structure of sample molecules.

当前NMR与MRI仪器存在射频线圈探测效率低、对超导磁体严重依赖、不能用于分析含铁磁性元素样品等问题。本项目采用基于原子磁力计的激光探测NMR方法，利用原子磁力计作为NMR磁探头，不但可解决上述问题，还具有体积小、功耗低等优点，可望实现成本低廉且便携式的NMR与MRI仪器。已有激光探测NMR多采用SERF原子磁力计，它工作温度高，影响样品弛豫，且样品传输较慢，导致其极化度损失较多。本项目针对这两个问题，利用自主研制的具有近室温工作原子探头的NMOR磁力计，并设计样品绝热传输装置与相应控制脉冲序列，降低NMR样品在预极化区与探测区传送时的极化度损失，研制出更灵敏的激光探测NMR谱仪；并用同位素13C标记乙醇等作为样品，获取高分辨率的J耦合谱。本项目实现的激光探测NMR方案，将进一步提高超低场或零场J耦合谱的分辨率，有望取得长程J耦合相互作用谱，获取样品分子的精细结构信息。

当前NMR 与MRI 仪器存在射频线圈探测效率低、对超导磁体严重依赖、不能用于分析含铁磁性元素样品等问题。本项目采用基于原子磁力计的激光探测NMR 方法，利用原子磁力计作为NMR 磁探头，不但可解决上述问题，还具有体积小、功耗低等优点，可望实现成本低廉且便携式的NMR 与MRI 仪器。已有激光探测NMR 多采用SERF 原子磁力计，它工作温度高，影响样品弛豫，且样品传输较慢，导致其极化度损失较多。本项目针对这两个问题，利用自主研制的具有近室温工作原子探头的NMOR 磁力计，并设计了样品绝热传输装置与相应的控制脉冲序列，降低NMR 样品在预极化区与探测区传送时的极化度损失，研制了更灵敏的激光探测NMR 谱仪；并用同位素13C 标记乙醇等作为样品，获取了高分辨率的J 耦合谱。本项目实现了激光探测NMR 方案，进一步提高了超低场或零场J 耦合谱的分辨率，得到了甲醇分子与乙醇分子的J耦合相互作用谱，测量得到了甲醇分子的J耦合常数为140.1 Hz，乙醇分子的J耦合常数为210.1 Hz，谱分辨率小于0.2Hz，可用于基于超低场或零场J 耦合谱的分子结构分析。