Coadsorption of CO and O2 on Fe(111)

Borgmann, D.; Kiessling, Wolfgang; Stadelmann, Matthias; Wedler, G.

doi:10.1016/0039-6028(91)91107-9

Cited by 10 publications

(2 citation statements)

References 9 publications

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“…Oxygen decreases the nonresonant signal by 4 times when adsorbed on the Fe(111) surface. The work function change for this system has previously been shown to be increased by 1.1 eV for 2 L of oxygen, adsorbed at 77 K, on the Fe(111) surface . Nitrogen adsorption also shows a decrease in nonresonant signal, which correlates with a 0.25 eV increase of the work function for Fe(111) upon adsorption of nitrogen …”

Section: Resultsmentioning

confidence: 68%

High-Pressure Ammonia Adsorption and Dissociation on Clean Fe(111) and Oxygen-Precovered Fe(111) Studied by Sum Frequency Generation Vibrational Spectroscopy

et al. 2004

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The adsorption of gases N2, H2, O2, and NH3 that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by Sum Frequency Generation (SFG) vibrational spectroscopy using an integrated ultrahigh vacuum/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH2 ( approximately 3325 cm-1) and NH ( approximately 3235 cm-1) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180 degrees between the resonant and nonresonant second-order nonlinear susceptibility of the surface, demonstrated as a reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr of ammonia and 0.5 Torr of oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180 degrees . The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates. Clean Fe(111) is found to have a large SFG nonresonant signal. The magnitude of the nonresonant signal was dependent on the adsorption species; O2 and N2 decrease, while H2 and NH3 increase the SFG nonresonant signal. The change in nonresonant signal is correlated to the change in work function for Fe(111) upon adsorption. Adsorption-induced changes in the SFG nonresonant signal was used as an indicator of surface conditions and to monitor surface reactions.

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Section: Resultsmentioning

confidence: 68%

High-Pressure Ammonia Adsorption and Dissociation on Clean Fe(111) and Oxygen-Precovered Fe(111) Studied by Sum Frequency Generation Vibrational Spectroscopy

et al. 2004

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“…The initial stage of the oxidation of a clean iron surface has been frequently studied by surface techniques and different results concerning the kinetics of this process has been obtained. − The rate of the oxygen adsorption decreases with the surface coverage with oxygen. The characteristic minimum on the line illustrating the dependence of the sticking coefficient of oxygen versus the surface coverage was frequently found for different metal surfaces and interpreted as the result of the oxide phase nucleation .…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the Initial Stage of the Oxidation of the Clean and Precovered with Nonmetals Iron Surface

Narkiewicz¹,

Arabczyk²

1999

Langmuir

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The oxidation of the iron surface has been studied using the Auger electron spectroscopy method, particularly the intermediate state of the process proceedings between a monolayer of oxygen and an oxide layer. The oxidation of the clean iron surface has been compared to that of the iron surface precovered with carbon, sulfur, nitrogen, and phosphorus. The monolayer of carbon or nitrogen does not affect the rate of the oxidation process; however the monolayer of sulfur or phosphorus inhibits the oxidation. The mechanism of the oxidation stage between the monolayer of oxygen and the oxide layer has been elucidated taking into account the incorporation of oxygen atoms into the first iron layer. The concentration of defects in the bidimensional adsorbate layer has been taken into consideration. The number of surface defects in the 2D lattice of sulfur or phosphorus is 20 times lower than in the layer of oxygen.

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Calorimetric Investigations of Processes at the Solid/Gas Interphase

Wedler

Ganzmann

Borgmann

1993

Ber Bunsenges Phys Chem

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Ahorption I Calorimetry I Kinetics I Metals I SurfacesAdsorption calorimetry, partially combined with thermal desorption spectroscopy and isotope exchange measurements, has been used to study the adsorption and coadsorption of gases on metal films under ultrahigh vacuum conditions. It has proved to be possible to get detailed information on both the primary adsorption step and the consecutive reaction in the adsorbed layer. Adsorption of CO and C 0 2 on Fe are treated as examples with subsequent decomposition reactions. In the case of the coadsorption of CO and O2 and of H2 and CO on Fe the mutual interaction of the gases including replacement processes are studied.E 8177

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Coadsorption of CO and O2 on Fe(111)

Cited by 10 publications

References 9 publications

High-Pressure Ammonia Adsorption and Dissociation on Clean Fe(111) and Oxygen-Precovered Fe(111) Studied by Sum Frequency Generation Vibrational Spectroscopy

High-Pressure Ammonia Adsorption and Dissociation on Clean Fe(111) and Oxygen-Precovered Fe(111) Studied by Sum Frequency Generation Vibrational Spectroscopy

Mechanism of the Initial Stage of the Oxidation of the Clean and Precovered with Nonmetals Iron Surface

Calorimetric Investigations of Processes at the Solid/Gas Interphase

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