A Study of Adsorption of CO on Hydrogen Covered Pt(111) Surface Using Electron-Stimulated Desorption Spectroscopy

Abstract

In cooling process of Pt(111) in an ultra high vacuum (UHV), hydrogen segregates and saturates on the surface. A time-of-flight type electron-Stimulated desorption (TOF-ESD) spectroscopy measures hydrogen ions desorbed from Pt(111) surface. The H⁺ signal intensity decreases with increasing of CO exposures on the H-saturated Pt(111) surface. After saturation of CO adsorption, TOF-ESD measures various intensities of the H⁺ and O⁺ (from CO) depending on specimen temperature. From the TOF-ESD results in the CO saturated surface, hydrogen is hidden under the subsurface due to CO adsorption. Desorption of hydrogen under layer of CO necessitates 80 K higher temperatures compared with CO free layer on Pt(111).