Physisorption of methane on grafoil studied by positrons

Journal Article · · Appl. Phys. Commun.; (United States)

OSTI ID:6286816

Wang, S J; Zhou, D M; Budhabhatti, S; Jean, J C

Positron annihilation spectroscopy (PAS) has been applied to study the physisorption phenomena of methane on grafoil surface. Positron lifetime and Doppler broadening due to electron motions in the annihilation radiation have been measured as a function of coverage (from submonolayer to four overlayer) and as a function of temperature. Both lifetime and Doppler broadening parameter increase as a function of adsorbate coverage below half monolayer, reach a maximum at half, and one and a half monolayer, and then decrease as a function of coverage. These variations are interpreted as a result of structural inhomogeneity (defect-type) created by the presence of methane molecules on the grafoil surface. The temperatures at which the significant lifetime changes occur correspond to the known solid-liquid phase transition temperature for 2D melting.

• Research Organization: Univ. of Missouri, Kansas City
• OSTI ID: 6286816
• Journal Information: Appl. Phys. Commun.; (United States), Journal Name: Appl. Phys. Commun.; (United States) Vol. 7:1-2; ISSN APCOD
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CARBON
DATA
ELECTROMAGNETIC INTERACTIONS
ELEMENTAL MINERALS
ELEMENTARY PARTICLES
ELEMENTS
EXPERIMENTAL DATA
FERMIONS
GRAPHITE
HYDROCARBONS
INFORMATION
INTERACTIONS
LEPTONS
LIFETIME
METHANE
MINERALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
POSITRONS
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE