کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5365700 | 1388336 | 2010 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Carbon monoxide adsorption on Co deposited Pt(1 0 0)-hex: IRRAS and LEED investigations Carbon monoxide adsorption on Co deposited Pt(1 0 0)-hex: IRRAS and LEED investigations](/preview/png/5365700.png)
Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on Pt(1Â 0Â 0) surfaces deposited with Co layers with different thicknesses. Pt(1Â 0Â 0) surfaces cleaned in ultrahigh vacuum showed surface reconstruction, i.e., Pt(1Â 0Â 0)-hex: two absorption bands ascribable to adsorbed CO on the 1Â ÃÂ 1 surface and hex domains emerge at 2086 and 2074Â cmâ1, respectively, after 1.0Â L CO exposure. Deposition of a 0.3-nm-thick-Co layer on Pt(1Â 0Â 0)-hex at 333Â K changes the low-energy electron diffraction (LEED) pattern from hex to p(1Â ÃÂ 1), indicating that the deposited Co lifts the reconstruction. The IRRAS spectrum for 1.0-L-CO-exposed Co0.3Â nm/Pt(1Â 0Â 0)-hex fabricated at 333Â K yields a single absorption band at 2059Â cmâ1. For Co0.3Â nm/Pt(1Â 0Â 0)-hex fabricated at 693Â K, the LEED pattern shows a less-contrasted hex and the pattern remains nearly unchanged even after CO exposure of 11Â L, although only 1.0Â L CO exposure to Pt(1Â 0Â 0)-hex lifts the surface reconstruction. A Co0.3Â nm/Pt(1Â 0Â 0)-hex surface fabricated at 753Â K exhibits an absorption band at 2077Â cmâ1, which is considered to originate from CO adsorbed on the Pt-enriched surface alloy. Co0.3Â nm/Pt(1Â 0Â 0)-hex surfaces fabricated above 773Â K show a clear hex-reconstructed LEED pattern, and the frequencies of the adsorbed CO bands are comparable to those of Pt(1Â 0Â 0)-hex, indicating that the deposited Co atoms are diffused near the surface region. The outermost surface of the 3.0-nm-thick-Co-deposited Pt(1Â 0Â 0)-hex is composed of Pt-Co alloy domains even at a deposition temperature of 873Â K. Based on the LEED and IRRAS results, the outermost surface structures of Cox/Pt(1Â 0Â 0)-hex are discussed.
Journal: Applied Surface Science - Volume 256, Issue 14, 1 May 2010, Pages 4517-4521