Nielsen Ulla Gro, Paik Younkee, Julmis Keinia, Schoonen Martin A A, Reeder Richard J, Grey Clare P
Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-2275, USA.
J Phys Chem B. 2005 Oct 6;109(39):18310-5. doi: 10.1021/jp051433x.
High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, the system representing an ideal model system for NMR studies. 6Li resonances with large hyperfine shifts (approximately 145 ppm) were observed above the goethite point of zero charge, providing clear evidence for the presence of Li-O-Fe connectivities, and thus the formation of an inner sphere Li+ complex on the goethite surface. Even larger Li hyperfine shifts (289 ppm) were observed for Li+-exchanged goethite, which contains lithium ions in the tunnels of the goethite structure, confirming the Li assignment of the 145 ppm Li resonance to the surface sites.
在室温下，可以获得针铁矿（α-FeOOH，粒径约4-10纳米）纳米晶体颗粒的高分辨率2H MAS NMR谱，这有助于在与环境相关的条件下进行吸附的NMR研究。研究了锂吸附作为pH的函数，该系统代表了用于NMR研究的理想模型系统。在针铁矿零电荷点以上观察到具有大约145 ppm大超精细位移的6Li共振，为存在Li-O-Fe连接提供了明确证据，从而在针铁矿表面形成内球Li+络合物。对于Li+交换的针铁矿，观察到甚至更大的Li超精细位移（289 ppm），其在针铁矿结构的通道中含有锂离子，证实了145 ppm Li共振的Li归属为表面位点。
