Schüttler Konstantin M, Bansmann Joachim, Engstfeld Albert K, Behm R Jürgen
Institute of Surface Chemistry and Catalysis, Ulm University, Albert-Einstein-Allee 47, D-89081 Ulm, Germany.
J Chem Phys. 2021 Sep 28;155(12):124704. doi: 10.1063/5.0054980.
As part of an extensive study of the interaction between Zn and Au in Zn/Au(111) model systems, we have systematically investigated the low-temperature (LT) nucleation and growth behavior of Zn on the Au(111) surface as well as the thermal stability of the resulting structures toward sintering, intermixing, and dissolution by scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS). Zn deposition at LT, at 105 K (STM) or 80 K (XPS), leads to nucleation and two-dimensional growth of Zn islands mainly at the elbows of the Au(111) herringbone reconstruction, with a slight preference for island formation at pinched-in (pi) rather than bulged-out (bu) elbows. Local surface intermixing during LT Zn deposition leads to local perturbations of the Au(111) herringbone reconstruction, which results in the formation of additional nucleation sites (edge sites). At higher coverages (>0.11 ML), island coalescence sets in. Testing the thermal stability by annealing experiments, we find the structures to be stable up to about 200 K, while at higher temperatures, 2D sintering, intermixing, and dissolution set in, with subtle differences between pi- and bu-elbow islands. This indicates largely comparable activation barriers for the underlying (surface-)diffusion and exchange processes. Upon annealing to 330 K, all island structures dissolved. Compared with previous reports on the growth of other metals on Au(111), Zn shows a rather high tendency for intermixing and can be considered to be typical of metal deposition systems with comparable barriers for 2D Zn detachment/sintering and intermixing/bulk diffusion.
作为对Zn/Au(111)模型系统中Zn与Au相互作用进行广泛研究的一部分，我们通过扫描隧道显微镜（STM）和X射线光电子能谱（XPS），系统地研究了Zn在Au(111)表面的低温（LT）成核和生长行为，以及所得结构在烧结、混合和溶解方面的热稳定性。在105 K（STM）或80 K（XPS）的低温下沉积Zn，会导致Zn岛主要在Au(111)人字形重构的肘部成核并二维生长，在收缩型（pi）肘部形成岛的倾向略高于鼓出型（bu）肘部。低温Zn沉积过程中的局部表面混合会导致Au(111)人字形重构的局部扰动，从而形成额外的成核位点（边缘位点）。在较高覆盖度（>0.11 ML）时，岛开始合并。通过退火实验测试热稳定性，我们发现这些结构在高达约200 K时是稳定的，而在较高温度下，二维烧结、混合和溶解开始，pi型和bu型肘部岛之间存在细微差异。这表明潜在的（表面）扩散和交换过程具有大致相当的活化能垒。退火至330 K时，所有岛状结构均溶解。与之前关于其他金属在Au(111)上生长的报道相比，Zn表现出相当高的混合倾向，可被视为二维Zn脱附/烧结以及混合/体扩散具有可比能垒的金属沉积系统的典型代表。
