The application of temperature-programmed desorption (TPD) techniques in heterogeneous catalysis to probe, among other things, the nature of the reactions on the surface solid catalyst, and ultimately, the kinetics of desorbed species, is hampered by the inability to make direct observations of adsorbates when they are most catalytically active. Thus, it is almost impossible to make a direct association between a given elementary surface process and a key feature on the TPD spectra, such as the nature and number of peaks. What kinetic Monte Carlo simulations have shown, on the other hand, is that the complex surface evolution during TPD is controlled effectively by just a few parameters that relate to the surface kinetics and energetics. In this study, we will use kinetic Monte Carlo approach to show that double-peaked TPD spectra obtained from adsorption of Bi adsorbates on Ni(100) at an initial temperature of 800 K and subsequent TPD runs for high preadsorbed coverages can indeed be explained satisfactorily by assuming predominant first-order desorption kinetics coupled with adsorbate-adsorbate lateral interactions, in agreement with prior studies. While not totally discounting the presence of Bi dimers, and thus second-order desorption, our study is sensitive enough to reveal the extent of their presence. In other words, we propose that dimers can coexist with Bi adatoms in small amounts while retaining the key features of the TPD spectra, provided the kinetic parameters associated with dimer formation (and dissolution) are well within a certain range. On the other hand, any model in which dimers are present to a degree in which they are not totally dominated by adatoms cannot produce TPD spectra that are consistent with the experiment.

中文翻译：

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动力学蒙特卡罗技术分析Ni在Ni（100）上程序升温脱附过程中一阶和二阶解吸过程的共存

温度编程解吸（TPD）技术在非均相催化中的应用，尤其是用于探测表面固体催化剂上反应的性质以及最终解吸的物质的动力学，因为无法进行直接观察而受到阻碍当它们最具有催化活性时。因此，几乎不可能在给定的基本表面过程和TPD光谱上的关键特征（例如峰的性质和数量）之间建立直接关联。另一方面，动力学蒙特卡洛模拟表明，TPD期间复杂的表面演化仅通过与表面动力学和高能相关的几个参数来有效控制。在这个研究中，我们将使用动力学蒙特卡洛方法来证明在800 K的初始温度下，Bi吸附物在Ni（100）上的吸附所获得的双峰TPD光谱，以及随后在高预吸附覆盖率下进行的TPD运行，确实可以通过假设主要为第一与先前研究一致的有序解吸动力学与被吸附物-被吸附物的侧向相互作用相结合。尽管不完全抵消Bi二聚体的存在，因此不排除二阶解吸，但我们的研究足够灵敏，可以揭示它们的存在程度。换句话说，我们建议二聚体可以与Bi原子少量共存，同时保留TPD光谱的关键特征，只要与二聚体形成（和溶解）相关的动力学参数在一定范围内即可。另一方面，