The structure of mixed H2O-OH monolayer films on Ru(0001)

Journal Article · Mon Oct 20 04:00:00 EDT 2008 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2988903· OSTI ID:942138

Tatarkhanov, M; Fomin, E; Salmeron, M; Andersson, K; Ogasawara, H; Pettersson, L G.M.; Nilsson, A; Cerda, J I

Scanning tunneling microscopy (STM) and x-ray absorption spectroscopy (XAS) have been used to study the structures produced by water on Ru(0001) at temperatures above 140 K. It was found that while undissociated water layers are metastable below 140 K, heating above this temperature produces drastic transformations whereby a fraction of the water molecules partially dissociate and form mixed H{sub 2}O-OH structures. XPS and XAS revealed the presence of hydroxyl groups with their O-H bond essentially parallel to the surface. STM images show that the mixed H{sub 2}O-OH structures consist of long narrow stripes aligned with the three crystallographic directions perpendicular to the close-packed atomic rows of the Ru(0001) substrate. The internal structure of the stripes is a honeycomb network of H-bonded water and hydroxyl species. We found that the metastable low temperature molecular phase can also be converted to a mixed H{sub 2}O-OH phase through excitation by the tunneling electrons when their energy is 0.5 eV or higher above the Fermi level. Structural models based on the STM images were used for Density Functional Theory optimizations of the stripe geometry. The optimized geometry was then utilized to calculate STM images for comparison with the experiment.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Materials Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 942138
• Report Number(s): LBNL-1194E
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ELECTRONS
EXCITATION
FERMI LEVEL
FUNCTIONALS
GEOMETRY
HEATING
SCANNING TUNNELING MICROSCOPY
STRUCTURAL MODELS
TRANSFORMATIONS
TUNNELING
WATER
X-RAY PHOTOELECTRON SPECTROSCOPY