1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Nat Commun. 2014 Nov 17;5:5441. doi: 10.1038/ncomms6441.
Heterogeneous processes at solid/gas, liquid/gas and solid/liquid interfaces are ubiquitous in modern devices and technologies but often difficult to study quantitatively. Full characterization requires measuring the depth profiles of chemical composition and state with enhanced sensitivity to narrow interfacial regions of a few to several nm in extent over those originating from the bulk phases on either side of the interface. We show for a model system of NaOH and CsOH in an ~1-nm thick hydrated layer on α-Fe2O3 (haematite) that combining ambient-pressure X-ray photoelectron spectroscopy and standing-wave photoemission spectroscopy provides the spatial arrangement of the bulk and interface chemical species, as well as local potential energy variations, along the direction perpendicular to the interface with sub-nm accuracy. Standing-wave ambient-pressure photoemission spectroscopy is thus a very promising technique for measuring such important interfaces, with relevance to energy research, heterogeneous catalysis, electrochemistry, and atmospheric and environmental science.
固/气、液/气和固/液界面的多相过程在现代设备和技术中无处不在，但往往难以定量研究。全面表征需要测量化学组成和状态的深度分布，以增强对界面窄区的灵敏度，该界面窄区的范围为几到几十纳米，超出界面两侧的体相起源。我们以α-Fe2O3（赤铁矿）上约 1nm 厚的水合层中 NaOH 和 CsOH 的模型体系为例，表明结合常压 X 射线光电子能谱和驻波光发射谱，可提供沿垂直于界面方向的体相和界面化学物种的空间排列，以及局部位能变化，其空间分辨率可达亚纳米级。因此，驻波常压光发射谱是测量此类重要界面的一种很有前途的技术，对于能源研究、多相催化、电化学以及大气和环境科学具有重要意义。
