水在FeO(111)上的吸附、解吸及聚集

Water adsorption, desorption, and clustering on FeO(111).

作者信息

Daschbach John L, Dohnalek Z, Liu Shu-Rong, Smith R Scott, Kay Bruce D

机构信息

Environmental Molecular Sciences Laboratory, Fundamental Science Division, Pacific Northwest National Laboratory, PO Box 999, Mail Stop K8-88, Richland, Washington 99352, USA.

出版信息

J Phys Chem B. 2005 May 26;109(20):10362-70. doi: 10.1021/jp058013s.

DOI:10.1021/jp058013s

PMID:16852256

Abstract

The adsorption of water on FeO(111) is investigated using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS). Well-ordered 2 ML thick FeO(111) films are grown epitaxially on a Pt(111) substrate. Water adsorbs molecularly on FeO(111) and desorbs with a well resolved monolayer peak. IRAS measurements as a function of coverage are performed for water deposited at 30 and 135 K. For all coverages (0.2 ML and greater), the adsorbed water exhibits significant hydrogen bonding. Differences in IRAS spectra for water adsorbed at 30 and 135 K are subtle but suggest that water adsorbed at 135 K is well ordered. Monolayer nitrogen TPD spectra from water covered FeO(111) surfaces are used to investigate the clustering of the water as a function of deposition or annealing temperature. Temperature dependent water overlayer structures result from differences in water diffusion rates on bare FeO(111) and on water adsorbed on FeO(111). Features in the nitrogen TPD spectra allow the monolayer wetting and 2-dimensional (2D) ordering of water on FeO(111) to be followed. Voids in a partially disordered first water layer exist for water deposited below 120 K and ordered 2D islands are found when depositing water above 120 K.

摘要

采用程序升温脱附（TPD）和红外反射吸收光谱（IRAS）研究了水在FeO(111)上的吸附。有序的2 ML厚的FeO(111)薄膜在Pt(111)衬底上外延生长。水以分子形式吸附在FeO(111)上，并以一个分辨良好的单层峰脱附。对在30 K和135 K沉积的水进行了作为覆盖度函数的IRAS测量。对于所有覆盖度（0.2 ML及以上），吸附的水表现出显著的氢键作用。在30 K和135 K吸附的水的IRAS光谱差异细微，但表明在135 K吸附的水排列有序。来自水覆盖的FeO(111)表面的单层氮TPD光谱用于研究水的聚集情况与沉积或退火温度的函数关系。与温度相关的水覆盖层结构源于水在裸露的FeO(111)上和吸附在FeO(111)上的水的扩散速率差异。氮TPD光谱中的特征使得能够追踪水在FeO(111)上的单层润湿和二维（2D）有序排列情况。对于在120 K以下沉积的水，部分无序的第一水层中存在空隙，而在120 K以上沉积水时会发现有序的2D岛。