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Coadsorption phases of CO and oxygen on Pd(111) studied by scanning tunneling microscopy
| Content Provider | Semantic Scholar |
|---|---|
| Author | Méndez, Javier Kim, Sang Hoon Cerdá, Jorge Wintterlin, Joost Ertl, Gerhard |
| Copyright Year | 2005 |
| Abstract | The adsorption of CO on an oxygen precovered Pds111d surface was investigated between 60 and 300 K. Applied methods were variable temperature scanning tunneling microscopy sSTMd and video STM to analyze the coadsorption structures. The STM data are compared with simulated STM images for the various surface phases in order to identify the appropiate structural model for each case. Low-energy electron diffraction and reaction isotherms by means of mass spectrometry were used to correlate the phases with the reaction yielding CO2. The video-STM data recorded during CO adsorption at 300 K on the s2 3 2dO phase show a fast phase transition into the s˛3 3˛3dR30 O structure, followed by reaction to CO2. The reaction only starts after completion of the phase transition, indicating that the s˛3 3˛3dR30O structure plays a crucial role for the reaction. At temperatures between 170 and 190 K the phase transition is slow enough to be monitored with STM. The experimental images of both the s2 3 2dO and the s˛3 3˛3dR30O structures are well reproduced by the simulations. Further CO adsorption caused a second phase transition into a ps2 3 1dO structure. The STM simulations strongly support a pure oxygen ps2 3 1d structure, rather than a mixed O + CO structure, in contrast to previous experimental work. The CO molecules form the same structures between the O islands that are known from the pure Pds111d/CO system. At lower temperatures, between 110 and 60 K, a so far unknown s2 3 2d phase was observed. The formation of this structure, and its imaging by the STM, show that it constitutes a mixed ps2 3 2dO+CO structure, where the oxygen atoms remain unchanged, and the CO molecules occupy hcp sites between the O atoms. |
| File Format | PDF HTM / HTML |
| DOI | 10.1103/PhysRevB.71.085409 |
| Volume Number | 71 |
| Alternate Webpage(s) | http://pubman.mpdl.mpg.de/pubman/item/escidoc:738916/component/escidoc:2052675/PhysRevB.71.085409.pdf |
| Alternate Webpage(s) | https://doi.org/10.1103/PhysRevB.71.085409 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
