College Park, Maryland      June 6 - 10 , 2004

M4-C5 (5:00 PM): Inelastic Neutron Scattering of H2 Adsorbed on Activated Carbon

D.G. Narehood, P.C. Eklund, P.E. Sokol (Department of Physics and Materials Research Institute, Pennsylvania State University Park, Pennsylvania 16802)

Inelastic neutron scattering provides a unique microscopic perspective of the state of molecules adsorbed on surfaces. We report inelastic neutron scattering studies of H2 adsorbed on an activated carbon (AC). Deep inelastic neutron scattering (DINS) has been used to probe the single-particle momentum distribution of the adsorbed molecules. From these measurements the mean kinetic energy, which is directly affected by the extent of localization of the molecules, has been determined. In addition to the DINS measurements, the rotational spectrum of the adsorbed molecules was measured with incident neutrons with thermal energies. Peaks corresponding to transitions between the J = 0 and J = 1 rotational states are present in the collected scattering spectra. These spectra provide information on the ortho-to-para conversion of the adsorbed molecules through the time-dependent intensities of the peaks. DINS and rotational spectra have been collected for various surface coverages in order to study the importance of the affect of H2-H2 interactions versus H2-AC interactions on the properties of the adsorbed molecules. This research was supported by the DOE under Grant No. DE-FG02-01ER45912.

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