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Titolo:
ADSORPTION AND DECOMPOSITION OF FORMIC-ACID ON MGO(001) SURFACE AS INVESTIGATED BY TEMPERATURE-PROGRAMMED DESORPTION AND SUM-FREQUENCY GENERATION SPECTROSCOPY - RECURRENCE INDUCED DEFECT SITES
Autore:
YAMAMOTO H; WATANABE N; WADA A; DOMEN K; HIROSE C;
Indirizzi:
TOKYO INST TECHNOL,RESOURCES UTILIZAT RES LAB,MIDORI KU,4259 NAGATSUTA YOKOHAMA KANAGAWA 226 JAPAN
Titolo Testata:
The Journal of chemical physics
fascicolo: 11, volume: 106, anno: 1997,
pagine: 4734 - 4744
SICI:
0021-9606(1997)106:11<4734:AADOFO>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
ENERGY LOSS SPECTROSCOPY; METAL-OXIDE SURFACES; VIBRATIONAL SPECTROSCOPY; CATALYTIC DECOMPOSITION; ZINC-OXIDE; TIO2(110) SURFACE; MAGNESIUM-OXIDE; BASE PROPERTIES; REACTION PATHS; MGO SURFACES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
78
Recensione:
Indirizzi per estratti:
Citazione:
H. Yamamoto et al., "ADSORPTION AND DECOMPOSITION OF FORMIC-ACID ON MGO(001) SURFACE AS INVESTIGATED BY TEMPERATURE-PROGRAMMED DESORPTION AND SUM-FREQUENCY GENERATION SPECTROSCOPY - RECURRENCE INDUCED DEFECT SITES", The Journal of chemical physics, 106(11), 1997, pp. 4734-4744

Abstract

The change of MgO(001) surface during the adsorption and thermal desorption of formic acid was investigated by temperature programmed desorption (TPD) and infrared-visible sum-frequency generation SFG spectroscopy. The TPD results revealed that the feature of desorption signals changed as the adsorption/thermal desorption process was repeated, despite no significant change of the low energy electron diffraction (LEED) pattern. The surface formate, produced by dissociative adsorption of formic acid, decomposed at 560 K and 700 K, giving H2O+CO and H-2+CO2 as primary and minor products, respectively, but the broad desorption peak of H2O started to appear at 300 K. The 560 K peak appeared froman early stage, while the 700 K peak gained intensity as the experiment was repeated and the density of defects increased. The adsorption site for the 700 K peak was ascribed to the catalytic reaction of magnesia powder. The SFG spectra gave three resonance peaks of CH stretching bands at 2850 cm(-1), 2870 cm(-1), and 2920 cm(-1) with a different dependence on the dose time, history of surface, and polarization of incident visible beam. The former two bands were assigned to the formates with bridged configuration, and the third band to the formate with unidentate configuration. The polarization dependence suggested that the CH bonds of bridged formates stood perpendicular to the surface, and that of the unidentate formate tilted approximately 30 degrees from the surface normal. A vibration nonresonant background signal was present on the SFG signal, showing characteristic dependence on the polarization of incident light beams, as well as the coverage and history ofthe surface, and was interpreted as originating from the defect siteson the surface. (C) 1997 American Institute of Physics.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/08/20 alle ore 22:49:11