Bedzyk M J, Bommarito G M, Caffrey M, Penner T L
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853.
Science. 1990 Apr 6;248(4951):52-6. doi: 10.1126/science.2321026.
The ion distribution in an electrolyte solution in contact with a charged polymerized phospholipid membrane was directly measured with long-period x-ray standing waves. The 27-angstrom-thick lipid monolayer was supported on a tungsten/silicon mirror. X-ray standing waves were generated above the mirror surface by total external reflection of a 9.8-kiloelectron volt x-ray beam from a synchrotron undulator. The membrane surface, which contained negatively charged phosphate headgroups, was bathed in a dilute ZnCl2 solution. The concentration of Zn2+ in the condensed layer at the membrane surface and the Zn2+ distribution in the diffuse layer were measured as a function of headgroup charge. The Debye length of the diffuse layer varied between 3 and 58 angstroms. The results qualitatively agree with the Gouy-Chapman-Stern model.
利用长周期X射线驻波直接测量了与带电聚合磷脂膜接触的电解质溶液中的离子分布。27埃厚的脂质单层支撑在钨/硅镜上。通过来自同步加速器波荡器的9.8千电子伏特X射线束的全外反射在镜表面上方产生X射线驻波。含有带负电荷磷酸头基团的膜表面浸泡在稀ZnCl2溶液中。测量了膜表面凝聚层中Zn2+的浓度以及扩散层中Zn2+的分布作为头基团电荷的函数。扩散层的德拜长度在3至58埃之间变化。结果与古依-查普曼-斯特恩模型定性一致。
