Physisorption of Nitrogen on Grafoil Studied by Doppler Broadening Measurement

Positron Annihilation Spectroscopy has been applied to study the physisorption of nitrogen on graphite surface. The Doppler broadening spectra have been measured as a function of the fractional monolayer coverage. The Doppler broadening S-parameter has a maximum at half monolayer. It is interpreted as a result of structural inhomogeneity (defect-type) created by the presence of nitrogen molecules on the graphite surface.