Surface species studied by angle-resolved product desorption: Emission mechanism and spatial distribution

Abstract

Recent progress and future developments in angle-resolved measurements of desorbing surface reaction products are reviewed for the analysis of surface species. Spatial and energy distributions of desorbing products with hyperthermal energy deliver the most direct structural information of the transition state including active intermediates and product formation sites.Knowledge of the desorption mechanism is requisite to achieve structural information since the method is directly linked to the chemical process. Structural analyses are exemplified in photoinduced O 2 desorption and CO oxidation, and compared with those from thermal N 2 O decomposition and CO oxidation as well as their applications to steady-state catalytic processes.

Mechanistische Einblicke in die Bindung und Aktivierung von N2O an Übergangsmetallzentren

“…Obwohl die N 2 O-Zerlegung auf definierten Metalloberflächen im Detail von den jeweiligen Oberflächenstrukturei-genschaften abhängt, konnte mithilfe experimenteller (winkelaufgelöster Desorption, Rastertunnelmikroskopie, Rönt-genabsorptions-Feinstrukturspektroskopie) [37][38][39] und theoretischer Methoden [39] ein allgemeines Bild der beteiligten Abläufe gezeichnet werden. Wie durch neuere theoretische Untersuchungen der Reaktion von N 2 O an Rh(111) [40,41] und Pd(110) [39,42] [43] Weiterhin belegte eine neuere Untersuchung zur N 2 O-Spaltung auf einer Cu 2 O(111)-Oberfläche, dass die h 1 -O-Koordination gegenüber der N-Koordination an Sauerstoffleerstellen auf der Oberfläche begünstigt ist.…”

Direct Chlorination of Ethene on ZnO (0001̅) by Hot Chlorine Atoms

“…Hot atoms can also be produced when the adsorbed molecules are dissociated by heat or photon on the surface. − Ertl and co-workers used low-temperature scanning tunneling microscopy (STM) to study and prove the existence of hot atoms following the dissociation of the chemisorbed O 2 molecule on Pt(111) . The oxidation of CO on Pt has been reported to proceed via a two-step reaction pathway (O 2 → 2O, O + CO → CO 2 ).…”

“…During the progress of this reaction, the O 2 molecules are thermally dissociated to produce hot oxygen atoms. Subsequently, the hot O atoms reacts with the adsorbed CO molecules on the surface. , Hot O atoms for CO oxidation could be produced when the Pt surface coadsorbed with O 2 and CO was irradiated by a laser. − It has also been proposed that hot O atoms can be produced when O 2 molecules impinge the surface of the substrate. , Lo and co-workers studied the hopping of the O atoms produced following the complete decomposition of H 2 O on Si(111) …”

Angle resolved intensity and velocity distributions of N2 desorbed by N2O decomposition on Rh(110)

“…10 Indeed, the measurements of crystal azimuth dependence of the product distributions have given the direct assignment of the structure for adsorbed species just before the desorption. 10 Indeed, the measurements of crystal azimuth dependence of the product distributions have given the direct assignment of the structure for adsorbed species just before the desorption.…”