Ultraviolet photoemission and thermal desorption studies of the chemisorption and decomposition of methanol on potassium-dosed Rh(111)

F. Solymosi, A. Berkó, Tibor I. Tarnóczi

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Abstract

The interaction of methanol with potassium-dosed (up to monolayer) Rh(111) surface has been studied by means of thermal desorption, ultraviolet photoemission (He II) spectroscopy and work function measurements. Preadsorbed potassium significantly influenced the adsorption, desorption, and stability of CH3OH on this Rh surface, but the pathway of the dissociation of CH3OH and its surface decomposition were not altered. An increase (6-10 kJ/mol) in the binding energy of chemisorbed CH3OH was found even in the low potassium coverage range, θK=0.05-0.26. At higher potassium coverages (θK=0.36, monolayer), where K exhibits mainly metallic character, the relative amount of irreversibly adsorbed methanol was greatly increased. In this case methoxy species was detected by He II photoemission studies: its complete decomposition occurred at around 492-505 K. The stabilization of the methoxy species was reflected in the high temperature for the evolution of H2(Tp=515 K), too. In the interpretation of the data a direct chemical interaction between methanol and potassium and the formation of a stable potassium methoxide is proposed.

Original languageEnglish
Pages (from-to)6745-6753
Number of pages9
JournalThe Journal of Chemical Physics
Volume87
Issue number11
Publication statusPublished - 1987

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Thermal desorption
Photoemission
Chemisorption
chemisorption
Methanol
potassium
Potassium
photoelectric emission
methyl alcohol
desorption
Decomposition
decomposition
Monolayers
Binding energy
Desorption
Stabilization
stabilization
binding energy
interactions
Spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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title = "Ultraviolet photoemission and thermal desorption studies of the chemisorption and decomposition of methanol on potassium-dosed Rh(111)",
abstract = "The interaction of methanol with potassium-dosed (up to monolayer) Rh(111) surface has been studied by means of thermal desorption, ultraviolet photoemission (He II) spectroscopy and work function measurements. Preadsorbed potassium significantly influenced the adsorption, desorption, and stability of CH3OH on this Rh surface, but the pathway of the dissociation of CH3OH and its surface decomposition were not altered. An increase (6-10 kJ/mol) in the binding energy of chemisorbed CH3OH was found even in the low potassium coverage range, θK=0.05-0.26. At higher potassium coverages (θK=0.36, monolayer), where K exhibits mainly metallic character, the relative amount of irreversibly adsorbed methanol was greatly increased. In this case methoxy species was detected by He II photoemission studies: its complete decomposition occurred at around 492-505 K. The stabilization of the methoxy species was reflected in the high temperature for the evolution of H2(Tp=515 K), too. In the interpretation of the data a direct chemical interaction between methanol and potassium and the formation of a stable potassium methoxide is proposed.",
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T1 - Ultraviolet photoemission and thermal desorption studies of the chemisorption and decomposition of methanol on potassium-dosed Rh(111)

AU - Solymosi, F.

AU - Berkó, A.

AU - Tarnóczi, Tibor I.

PY - 1987

Y1 - 1987

N2 - The interaction of methanol with potassium-dosed (up to monolayer) Rh(111) surface has been studied by means of thermal desorption, ultraviolet photoemission (He II) spectroscopy and work function measurements. Preadsorbed potassium significantly influenced the adsorption, desorption, and stability of CH3OH on this Rh surface, but the pathway of the dissociation of CH3OH and its surface decomposition were not altered. An increase (6-10 kJ/mol) in the binding energy of chemisorbed CH3OH was found even in the low potassium coverage range, θK=0.05-0.26. At higher potassium coverages (θK=0.36, monolayer), where K exhibits mainly metallic character, the relative amount of irreversibly adsorbed methanol was greatly increased. In this case methoxy species was detected by He II photoemission studies: its complete decomposition occurred at around 492-505 K. The stabilization of the methoxy species was reflected in the high temperature for the evolution of H2(Tp=515 K), too. In the interpretation of the data a direct chemical interaction between methanol and potassium and the formation of a stable potassium methoxide is proposed.

AB - The interaction of methanol with potassium-dosed (up to monolayer) Rh(111) surface has been studied by means of thermal desorption, ultraviolet photoemission (He II) spectroscopy and work function measurements. Preadsorbed potassium significantly influenced the adsorption, desorption, and stability of CH3OH on this Rh surface, but the pathway of the dissociation of CH3OH and its surface decomposition were not altered. An increase (6-10 kJ/mol) in the binding energy of chemisorbed CH3OH was found even in the low potassium coverage range, θK=0.05-0.26. At higher potassium coverages (θK=0.36, monolayer), where K exhibits mainly metallic character, the relative amount of irreversibly adsorbed methanol was greatly increased. In this case methoxy species was detected by He II photoemission studies: its complete decomposition occurred at around 492-505 K. The stabilization of the methoxy species was reflected in the high temperature for the evolution of H2(Tp=515 K), too. In the interpretation of the data a direct chemical interaction between methanol and potassium and the formation of a stable potassium methoxide is proposed.

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