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电子中残余气体与成象电子相互碰撞,即气体分子对电子产生散射,使电镜中的图象反差变坏。尤其是为了观察活的生物样品,必须把生物放在相对湿度大于85％,并接近一个大气压的气体中,否则生物细胞会脱水,失去活力。这种情况下,气体对电子的散射就更为突出,严重地影响图象反差,使图象分辨率降低。为此,我们研究了气体对电子的散射,测定了不同气体的散射截面。试验是在超高压电镜上进行的。采用为观察活生物样品而专门设计的差动泵充气样品室,这样可以得到几个
Electrons in the residual gas and imaging electron collide with each other, that gas molecules on the scattering of electrons, electron microscope image contrast worse. In particular, in order to view living biological samples, the organism must be placed in a gas at a relative humidity greater than 85% and approaching one atmosphere, or the biological cells may dehydrate and lose their vitality. In this case, the gas is more prominent on the electron scattering, seriously affecting the image contrast, the image resolution is reduced. For this reason, we have studied the scattering of electrons by electrons and measured the scattering cross sections of different gases. The test was carried out on a UHV electron microscope. Using a specially designed differential pump aerated sample chamber for viewing live biological samples, several