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三、在催化研究中的应用 1.ISS用于具有规整表面的模型催化剂的研究 (1) 确定表面组成的定性与定量分析通常,用ISS定性分析规整的模型催化剂是比较容易的,但也有例外,如当入射离子的能量较低(<200—300ev)时,离子与表面原子的作用时间较长,原子对离子的运动轨迹影响较大,使实验结果偏离式(3)的理论值;或在样品导电性能差引起表面电荷积累时也会偏离理论值,此时的定性分析需要较多的对比考虑等技巧。 ISS的定量分析比定性分析困难得多。在同一表面上,原子序较低与较高的元素其灵敏度相差很大。同种元素以不同方式存在时,如在体相中或作为吸附质时其灵敏度可能大不相同。例如,作者所在实验室曾在
III. APPLICATIONS IN CATALYST STUDIES 1.ISS RESEARCH ON MODEL CATALYSTS WITH REGULAR SURFACES (1) Qualitative and Quantitative Analysis to Determine Surface Compositions It is generally easier to qualitatively characterize structured catalyst models with ISS, with the exception of For example, when the energy of the incident ion is low (<200-300 eV), the action time of the ions with the surface atoms is longer and the influence of the atoms on the trajectories of the ions is larger, so that the experimental results deviate from the theoretical value of the formula (3); or In the sample poor conductivity caused by surface charge accumulation will deviate from the theoretical value, the qualitative analysis at this time need more consideration and other techniques. Quantitative analysis of ISS is much more difficult than qualitative analysis. On the same surface, the lower the atomic order and the higher the element’s sensitivity is quite different. The same kind of element exists in different ways, such as in the bulk or as adsorbate when its sensitivity may be very different. For example, the author’s lab was there