Yonehara K, Baba N, Kanaya K
Naka Works, Hitachi Ltd., Ibaraki, Japan.
J Electron Microsc Tech. 1989 May;12(1):71-7. doi: 10.1002/jemt.1060120110.
The term "etching," in electron microscopy, refers to the removal of specimen surface layers and includes chemical, electrolytic, and ion-beam methods. The ion-beam etching process is used to remove layers of a target material by bombarding it with ionized gas molecules. Recently, the method has been applied to the field of biological specimens; however, the practical procedures for such organic materials have not been developed. In the present study, we used an apparatus in which a beam of argon ions is collimated and focused by electrostatic lenses onto an appropriate target. We demonstrated the optimum conditions to observe biological specimens that were treated with osmium tetroxide and tannic acid. The specimens were examined uncoated at low accelerating voltage using a field emission scanning electron microscope. According to our experiments, when a biological specimen was observed under high-resolution conditions at over 50,000x magnification, the optimum condition of ion-beam etching consisted of an accelerating volage of E = 1 keV and an ion-beam dose of It = 360-400 microA.min, depending on parts of the specimens. In order to decrease overetching, we had to choose factors such as E = 1-2 keV and It = 500 microA.min.
在电子显微镜学中，“蚀刻”一词是指去除样品表面层，包括化学法、电解法和离子束法。离子束蚀刻工艺是通过用离子化气体分子轰击靶材料来去除其各层。最近，该方法已应用于生物样品领域；然而，针对此类有机材料的实际操作方法尚未开发出来。在本研究中，我们使用了一种装置，其中氩离子束通过静电透镜准直并聚焦到合适的靶上。我们展示了观察经四氧化锇和单宁酸处理的生物样品的最佳条件。使用场发射扫描电子显微镜在低加速电压下对未镀膜的样品进行检查。根据我们的实验，当在超过50000倍放大率的高分辨率条件下观察生物样品时，离子束蚀刻的最佳条件包括：加速电压E = 1 keV，离子束剂量It = 360 - 400微安·分钟，具体取决于样品的部位。为了减少过度蚀刻，我们必须选择诸如E = 1 - 2 keV和It = 500微安·分钟等参数。
