Roinel N
Pflugers Arch. 1981 Apr;390(1):54-5. doi: 10.1007/BF00582711.
The effect of low temperatures on the stability of characteristic signals during electron probe analysis of microdroplets has been investigated. The kinetics of the characteristic Na, K and Cl signals from lyophilized droplets of either KCl or NaCl salts were observed for 1200 s within an electron microprobe whose specimen stage was maintained at -140 degrees C. Samples were irradiated with 15 keV electrons, at beam current densities ranging from 7 x 10(-4) to 7 x 10(-3) A . cm-2. The signals measured increased and then, in some cases, decreased. The duration and amplitude of the increases varied depending on beam current density, mass thickness of the sample and on the element concerned. The increase sometimes reached 6 times the initial value, a level never observed at room temperature. No proportionality was observed between X-ray intensity and concentration for measurements after the first 10 s irradiation. Proportionality was only restored when droplets had been irradiated for some time. In no case did the stability of characteristic signals improve. Analysis of droplets at -140 degrees C suggests that under electron beam irradiation they undergo a change not observable at room temperature.
研究了低温对微滴电子探针分析过程中特征信号稳定性的影响。在样品台保持在-140℃的电子微探针内，对KCl或NaCl盐冻干微滴的特征Na、K和Cl信号的动力学进行了1200秒的观测。用15keV电子照射样品，束流密度范围为7×10⁻⁴至7×10⁻³A·cm⁻²。测量的信号先增加，然后在某些情况下下降。增加的持续时间和幅度取决于束流密度、样品的质量厚度以及相关元素。增加有时达到初始值的6倍，这是在室温下从未观察到的水平。在照射最初10秒后的测量中，未观察到X射线强度与浓度之间的比例关系。只有在微滴照射一段时间后，比例关系才恢复。在任何情况下，特征信号的稳定性都没有改善。在-140℃对微滴进行分析表明，在电子束照射下，它们会发生在室温下无法观察到的变化。
