Trapping-mediated dissociative chemisorption of ethane on Ir(110)-(1 times 2)

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.457762· OSTI ID:7140843

Mullins, C B; Weinberg, W H ^[1]

---

1. Department of Chemical Engineering, University of California, Santa Barbara, California 93106 (USA)

Evidence is presented to support a trapping-mediated dissociative chemisorption mechanism for ethane interacting with an Ir(110)-(1{times}2) surface. The data were obtained from supersonic molecular-beam measurements with an incident kinetic energy {ital E}{sub {ital i}} ranging between 1.2 and 24.1 kcal/mol, a surface temperature {ital T}{sub {ital s}} between 154 and 500 K, and an incident angle {theta}{sub {ital i}} between 0{degree} and 45{degree}. For {ital E}{sub {ital i}} less than approximately 13 kcal/mol, the probability of dissociative chemisorption {ital S}{sub 0} decreases rapidly with increasing {ital T{sub s}}. For a surface temperature of 154 K, {ital S}{sub 0} decreases with increasing {ital E}{sub {ital i}} for 1.2{le}{ital E}{sub {ital i}} {le}13.4 kcal/mol, consistent with a trapping-mediated chemisorption mechanism. Indeed, the data also support quantitatively a kinetic model consistent with a trapping-mediated chemisorption mechanism. The difference in the activation energies for desorption and chemisorption from the physically adsorbed, trapped state {ital E}{sub {ital d}} {minus}{ital E}{sub {ital c}} is 2.2{plus minus}0.2 kcal/mol. In the trapping-mediated regime, S{sub 0} is found to be rather insensitive to incident angle, scaling with {ital E}{sub {ital i}} cos{sup 0.5} {theta}{sub {ital i}} .

• DOE Contract Number: FG03-89ER14048
• OSTI ID: 7140843
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:7; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
BEAMS
CATALYSIS
CHEMICAL REACTIONS
CHEMISORPTION
DISSOCIATION
ELEMENTS
ENERGY
ENERGY TRANSFER
ETHANE
HIGH TEMPERATURE
HYDROCARBONS
INCIDENCE ANGLE
IRIDIUM
KINETIC ENERGY
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
MOLECULAR BEAMS
ORGANIC COMPOUNDS
PLATINUM METALS
SEPARATION PROCESSES
SORPTION
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENTS
TRAPPING