Nagasaka Masanari, Kondoh Hiroshi, Nakai Ikuyo, Ohta Toshiaki
Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Chem Phys. 2005 Jan 22;122(4):44715. doi: 10.1063/1.1835270.
The formation of oxygen islands on the Pt(111) surface has been studied as a function of temperature by low energy electron diffraction (LEED) experiments and dynamic Monte Carlo (DMC) simulations. By raising the temperature, the (2 x 2) LEED spot intensity increases gradually and decays after a peak at around 255 K (T(p)) with full width of half maximum of 160 K. This behavior is interpreted by DMC simulations with the kinematical LEED analysis. In the DMC simulation, an oxygen atom hops to the neighboring site via the activation barrier of the saddle point. The potential energies at initial, saddle, and final points are changed at each hopping event depending on the surrounding oxygen atoms. By comparing the observed T(p) with the simulated one, the interaction energy E of oxygen atoms on Pt(111) was determined to be 25+/-3 meV at 2a(0). The DMC simulations visualize how the oxygen islands are formed and collapse on Pt(111) with increase of the temperature and well reproduce the surface configurations observed by scanning tunneling microscopy.
通过低能电子衍射（LEED）实验和动态蒙特卡罗（DMC）模拟，研究了Pt(111)表面氧岛的形成与温度的关系。随着温度升高，(2×2) LEED斑点强度逐渐增加，并在约255 K（T(p)）达到峰值后衰减，半高宽为160 K。通过运动学LEED分析的DMC模拟对这种行为进行了解释。在DMC模拟中，氧原子通过鞍点的活化能垒跳跃到相邻位置。每次跳跃事件中，初始、鞍点和终点的势能会根据周围氧原子而变化。通过将观察到的T(p)与模拟值进行比较，确定在2a(0)时Pt(111)上氧原子的相互作用能E为25±3 meV。DMC模拟直观展示了随着温度升高氧岛在Pt(111)上如何形成和崩塌，并很好地再现了扫描隧道显微镜观察到的表面构型。
