Photoinduced generation of CO[sub 2][sup [minus]] anion radical on K-promoted Rh(111) surface

• Published in: Journal of physical chemistry (1952) Vol. 98:33
• Main Authors: Solymosi, F., Klivenyi, G.
• Format: Journal Article
• Language: English
• Published: United States 18-08-1994
• Subjects: 10 SYNTHETIC FUELS; 400102 > Chemical & Spectral Procedures; 400201 > Chemical & Physicochemical Properties; 400500 > Photochemistry; ADSORPTION; ALKALI METALS; ANIONS; CARBON COMPOUNDS; CARBON DIOXIDE; CARBON OXIDES; CHALCOGENIDES; CHARGED PARTICLES; CHEMICAL REACTIONS; DECOMPOSITION; ELECTRON SPECTROSCOPY; ELEMENTS; ENERGY-LOSS SPECTROSCOPY; FUNCTIONS; HALOGENS; HYDROGEN; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IODINE; IONS; METALS; NONMETALS; OXIDES; OXYGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; PHOTOLYSIS; PLATINUM METALS; POTASSIUM; RADICALS; RHODIUM; SOLID CLUSTERS; SORPTION; SPECTROSCOPY; SURFACE PROPERTIES; TRANSITION ELEMENTS 100200 > Synthetic Fuels > Production > (1990-); WORK FUNCTIONS
• ISSN: 0022-3654; 1541-5740
• DOI: 10.1021/j100084a024

Photoinduced formation of the CO[sub 2][sup [minus]] anion radical was investigated Rh(111) surfaces that were clean or covered with hydrogen, iodine, or potassium. The methods used were high-resolution electron energy loss spectroscopy (HREELS) and thermal desorption spectroscopy. Illumination of CO[sub 2] adsorbed on a clean Rh(111) 0surface with a 100-W Hg are lamp produced no HREEL spectral signals indicative of the formation of CO[sub 2][sup [minus]]. The same was observed for the hydrogen- and iodine-promoted surfaces. However, in the presence of potassium adatoms, which lowered the work function of the metal by 3.5-4.0 eV, illumination of the adsorbed CO[sub 2] induced or enhanced formation of the CO[sub 2][sup [minus]] radical even at 90 K. New loss features attributed to the asymmetric stretch, to the symmetric stretch, and to the bending mode of the bent CO[sub 2][sup [minus]] appeared at 1610, 1320, and 830 cm[sup [minus]1] in the HREEL spectrum of Rh(111). The presence of the species CO[sub 2][sup [minus]] on the surface led to an enhancement of the amount of physisorbed CO[sub 2], as indicated by significantly higher losses at 2350 and 640 cm[sup [minus]1]. This suggests the coupling between neutral and charged CO[sub 2][sup [minus]] to yield a cluster compound (CO[sub 2][center dot]CO[sub 2][sup [minus]]), which is known to exist in the gas phase. 22 refs., 7 figs., 1 tab.