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Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry

Schießer, Alexander ; Hörtz, Peter ; Schäfer, Rolf (2010)
Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry.
In: Surface Science, 604 (23-24)
doi: 10.1016/j.susc.2010.09.001
Artikel, Bibliographie

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Kurzbeschreibung (Abstract)

The adsorption and desorption of the system CO/Pt(111) and C6H6/Pt(111) at 300 K has been investigated with a pulsed molecular beam method in combination with a microcalorimeter. For benzene the sticking probability has been measured in dependence of the coverage θ. For coverages θ > 0.8 transient adsorption is observed. From an analysis of the time-dependence of the molecular beam pulses the rate constant for desorption is determined to be 5.6 s− 1. With a precursor-mediated kinetic adsorption model this allows to obtain also the hopping rate constant of 95.5 s− 1. The measured adsorption enthalpies could be best described by (199 − 77θ − 51θ2) kJ/mol, in good agreement with the literature values. For CO on Pt(111) also transient adsorption has been observed for θ > 0.95 at 300 K. The kinetic analysis yields rate constants for desorption and hopping of 20 s−1 and 51 s−1, respectively. The heats of adsorption show a linear dependence on coverage (131 − 38θ) kJ/mol between 0 ≤ θ ≤ 0.3, which is consistent with the desorption data from the literature. For higher coverage (up to θ = 0.9ML) a slope of −63 kJ/mol describes the decrease of the differential heat of adsorption best. This result is only compatible with desorption experiments, if the pre-exponential factor decreases strongly at higher coverage. We found good agreement with recent quantum chemical calculations made for (θ = 0.5ML).

Typ des Eintrags: Artikel
Erschienen: 2010
Autor(en): Schießer, Alexander ; Hörtz, Peter ; Schäfer, Rolf
Art des Eintrags: Bibliographie
Titel: Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry
Sprache: Englisch
Publikationsjahr: 2010
Ort: Darmstadt
Verlag: Elsevier
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Surface Science
Jahrgang/Volume einer Zeitschrift: 604
(Heft-)Nummer: 23-24
DOI: 10.1016/j.susc.2010.09.001
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Kurzbeschreibung (Abstract):

The adsorption and desorption of the system CO/Pt(111) and C6H6/Pt(111) at 300 K has been investigated with a pulsed molecular beam method in combination with a microcalorimeter. For benzene the sticking probability has been measured in dependence of the coverage θ. For coverages θ > 0.8 transient adsorption is observed. From an analysis of the time-dependence of the molecular beam pulses the rate constant for desorption is determined to be 5.6 s− 1. With a precursor-mediated kinetic adsorption model this allows to obtain also the hopping rate constant of 95.5 s− 1. The measured adsorption enthalpies could be best described by (199 − 77θ − 51θ2) kJ/mol, in good agreement with the literature values. For CO on Pt(111) also transient adsorption has been observed for θ > 0.95 at 300 K. The kinetic analysis yields rate constants for desorption and hopping of 20 s−1 and 51 s−1, respectively. The heats of adsorption show a linear dependence on coverage (131 − 38θ) kJ/mol between 0 ≤ θ ≤ 0.3, which is consistent with the desorption data from the literature. For higher coverage (up to θ = 0.9ML) a slope of −63 kJ/mol describes the decrease of the differential heat of adsorption best. This result is only compatible with desorption experiments, if the pre-exponential factor decreases strongly at higher coverage. We found good agreement with recent quantum chemical calculations made for (θ = 0.5ML).

Freie Schlagworte: Microcalorimetry, Sticking probability, Adsorption energies, Carbon monoxide, Benzene, Pt(111)
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 540 Chemie
Fachbereich(e)/-gebiet(e): 07 Fachbereich Chemie
07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Anorganische Chemie
07 Fachbereich Chemie > Eduard Zintl-Institut
07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Physikalische Chemie
Hinterlegungsdatum: 02 Aug 2024 12:53
Letzte Änderung: 02 Aug 2024 12:53
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