所谓不稳定样品是指在电子轰击下,样品局部产生离子迁移,蒸发或分解等物理化学作用,导致元素特征X射线强度随时间变化的一种现象,它严重影响正常的图象观察与定量分析。不稳定样品主要是一些导热率较差的物质,例如玻璃、钠长石、某些含银的矿物、卤化物、磷酸盐、含水较高的矿物、火山产物、实验岩石产物、陶瓷、氢氧化铝、塑料以及生物样品等。至今研究较多的是玻璃和长石。在常用的实验条件下,Na、K的X射线强度随时间迅速地衰减,相反地,Si、Al、Ca和Mg则略为增强,并在一定时间之后达到平衡。这被解释为,由于电子的作用使离子化合物中氧化物离解为两种离子,氧离子迁移到表面,在炭膜下生成气泡,造成炭膜破裂,离子迁移率较高的Na和K,在一定 The so-called unstable sample refers to the phenomenon of partial ionization, evaporation or decomposition of the sample caused by the electron bombardment, resulting in the phenomenon that the characteristic X-ray intensity of the element changes with time, which seriously affects normal image observation and quantitative analysis . Unsteady samples are mainly those with poor thermal conductivity, such as glass, albite, certain silver-containing minerals, halides, phosphates, higher water-containing minerals, volcanic products, experimental rock products, ceramics, Aluminum, plastic and biological samples. So far more research is glass and feldspar. Under common experimental conditions, the X-ray intensities of Na and K rapidly decay with time. On the contrary, Si, Al, Ca and Mg are slightly enhanced and reach equilibrium after a certain period of time. This is interpreted as the dissociation of the oxide in the ionic compound into two kinds of ions due to the action of the electrons, the migration of oxygen ions to the surface, the generation of air bubbles under the carbon film, resulting in rupture of the carbon film and high ion mobility of Na and K for sure