Sigee D C, Gilpin C
Department of Biological Sciences, University of Manchester, UK.
Scanning Microsc Suppl. 1994;8:219-27; discussion 227-9.
X-ray microanalysis of non-biological and biological specimens was carried out in an environmental scanning electron microscope (ESEM) over a range of atmospheric conditions. Introduction of water vapour into the specimen chamber lead to direct X-ray contribution from oxygen atoms, an increase in extraneous background (causing reduced P/B ratios of other elements), X-ray absorption (also reducing P/B ratios) and broadening (skirting) of the electron beam. Similar results were obtained after introduction of an argon atmosphere. These effects were reduced under conditions of minimal chamber atmospheric pressure and maximal accelerating voltage. Because of beam skirting, quantitative X-ray microanalysis of biological specimens in a water vapour atmosphere was only valid where the sample was spread over a wide area (leading to mean elemental values for the whole preparation). Unless appropriate correction factors or changes in instrumentation can be implemented, quantitative analysis of wet specimens in ESEM cannot be applied to discrete specimens or to limited areas within a mixed sample.
在一系列大气条件下，利用环境扫描电子显微镜（ESEM）对非生物和生物标本进行了X射线微分析。向样品室中引入水蒸气会导致氧原子产生直接的X射线贡献、外来背景增加（导致其他元素的P/B比降低）、X射线吸收（也会降低P/B比）以及电子束展宽（边缘效应）。引入氩气气氛后也得到了类似的结果。在样品室气压最小和加速电压最大的条件下，这些影响会减小。由于电子束边缘效应，在水蒸气气氛中对生物标本进行定量X射线微分析仅在样品大面积分布时有效（从而得到整个制剂的平均元素值）。除非能够采用适当的校正因子或对仪器进行改进，否则ESEM中对湿标本的定量分析不能应用于离散标本或混合样品中的有限区域。
