In- Focus Electrostatic Zach Phase Plate Imaging for Transmission Electron Microscopy with Tunable Phase Contrast of Frozen Hydrated Biological Samples
In- Focus Electrostatic Zach Phase Plate Imaging for Transmission Electron Microscopy with Tunable Phase Contrast of Frozen Hydrated Biological Samples
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DOI：
10.1017/s1431927613013901
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发表时间：
2014-02-01
影响因子：
2.8
通讯作者：
Schroeder, Rasmus R.
中科院分区：
文献类型：
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作者：
Frindt, Nicole;Oster, Marco;Schroeder, Rasmus R.
对光束敏感的弱相物体（如生物冷冻样品）的透射电子显微镜（TEM）图像通常显示出非常低的信噪比。这些样品几乎没有振幅对比，相反，结构信息主要编码在相位对比中。为了提高图像中样品的对比度，特别是在低空间频率下，使用相位片在TEM中进行近焦相位对比度增强已经被讨论了很长时间。静电相板尤其有利，因为它们的可调谐电位将允许最佳的相移调整和更高的分辨率，而不是薄膜相板，因为它们避免了物质中的额外散射事件。在这里，我们展示了使用静电扎克相板获得的肌动蛋白丝冷冻样品的近焦相衬图像的首次实现。通过在相板上施加适当的电位，可以得到正负相衬。相对于相位板，相位对比改善对样品方向的依赖被证明，并讨论了单边带伪影。此外，还显示了减少相板污染和充电效应的可能性。
Transmission electron microscopy (TEM) images of beam sensitive weak-phase objects such as biological cryo samples usually show a very low signal-to-noise ratio. These samples have almost no amplitude contrast and instead structural information is mainly encoded in the phase contrast. To increase the sample contrast in the image, especially for low spatial frequencies, the use of phase plates for close to focus phase contrast enhancement in TEM has long been discussed. Electrostatic phase plates are favorable in particular, as their tunable potential will allow an optimal phase shift adjustment and higher resolution than film phase plates as they avoid additional scattering events in matter. Here we show the first realization of close to focus phase contrast images of actin filament cryo samples acquired using an electrostatic Zach phase plate. Both positive and negative phase contrast is shown, which is obtained by applying appropriate potentials to the phase plate. The dependence of phase contrast improvement on sample orientation with respect to the phase plate is demonstrated and single-sideband artifacts are discussed. Additionally, possibilities to reduce contamination and charging effects of the phase plate are shown.