Compostional Imaging with Energy Filtered Scanning Transmission Electron Microscopy

该研究小组将开发绘制 细胞膜和细胞器在2nm-3 nm处的组成 分辨率，与200千伏场发射枪<$FEG！-配备 平行电子接口电子显微镜 能量损失谱仪（并行EELS）和X射线 检测器 物理学家和生物学家将合作， 开发定量分析所需的特殊技术 低浓度元素的成像（例如，Ca、P、Gd） 在生物冷冻切片中。 EEL的主要障碍是 由于冷冻切片的厚度， 通过使用200 kV励磁和通过 优化方法的理论和实验发展 光谱收集和数据分析。 EELS谱 在每个扫描像素处收集的图像将是最少的倍数。 平方拟合的算法，考虑到 的贡献的复数等离子体散射，并在 高损失区，碳能损失及其细 结构和EELS的L边缘（例如钾） 背景 电子光学元件将被设计 并添加到现有的并行EELS系统，以纠正 降低检测灵敏度的增益变化。 高 结合到膜上的Ca的分辨率组成图，或 在细胞器和磷酸化位点的隔离， 具有广泛的生物学应用，并将被探索。

This research group will develop methods for mapping the composition of cell membranes and organelles at 2nm-3nm resolution, with a 200kV field emission gun ıFEG!-equipped electron microscope interfaced with a parallel electron energy loss spectrometer (parallel EELS) and an X-ray detector. Physicists and biologists will collaborate to develop the special techniques required for quantitative imaging of low-concentrations of elements (e.g., Ca, P, Gd) in biological cryosections. The major obstacle to EELS, the large background due to the thickness of cryosections, will be overcome by the use of 200kV excitation and through theoretical and experimental development of optimal methods of spectral collection and data analysis. EELS spectra collected at each scanned pixel will be multiple least squares fitted with algorithms that take into account the contributions of plural plasmon scattering and, in the higher loss region, the carbon energy loss and its fine structure, and L-edges (e.g. potassium)to the EELS background. Electron optical components will be designed and added to an existing parallel EELS system to correct the gain variations that reduce detection sensitivities. High resolution compositional mapping of Ca-bound to membranes or sequestered in organelles and of phosphorylation sites will have broad biological applications and will be explored.