Novotny Zbynek, Tobler Benjamin, Artiglia Luca, Fischer Martin, Schreck Matthias, Raabe Jörg, Osterwalder Jürg
Physik-Institut, Universität Zürich, CH-8057 Zürich, Switzerland.
Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland.
J Phys Chem Lett. 2020 May 7;11(9):3601-3607. doi: 10.1021/acs.jpclett.0c00914. Epub 2020 Apr 23.
Using time-lapsed ambient-pressure X-ray photoelectron spectroscopy, we investigate the thermal oxidation of single-crystalline Ir(100) films toward rutile IrO(110) in situ. We initially observe the formation of a carbon-free surface covered with a complete monolayer of oxygen, based on the binding energies of the Ir 4f and O 1s core level peaks. During a rather long induction period with nearly constant oxygen coverage, the work function of the surface changes continuously as sensed by the gas phase O 1s signal. The sudden and rapid formation of the IrO rutile phase with a thickness above 3 nm, manifested by distinct binding energy changes and substantiated by quantitative XPS analysis, provides direct evidence that the oxide film is formed via an autocatalytic growth mechanism that was previously proposed for PbO and RuO.
我们使用时间分辨常压X射线光电子能谱，原位研究了单晶Ir(100)薄膜向金红石型IrO(110)的热氧化过程。基于Ir 4f和O 1s芯能级峰的结合能，我们最初观察到形成了一个无碳表面，该表面覆盖有完整的单层氧。在氧气覆盖率几乎恒定的相当长的诱导期内，气相O 1s信号表明表面功函数不断变化。IrO金红石相突然快速形成，厚度超过3 nm，这通过明显的结合能变化表现出来，并经定量XPS分析证实，直接证明了氧化膜是通过先前针对PbO和RuO提出的自催化生长机制形成的。
