COLL 14 |
| The possibility of having positronium (Ps) physisorbed at a material surface is of great fundamental interest, since it can lead to new insight regarding quantum sticking and is a necessary first step to try to obtain a Ps2 molecule on a material host. Experimental evidence for physisorbed Ps at the surface of quartz was reported some years ago[Sferlazzo, Berko, Canter, Phys. Rev. B 3, 6067 (1985)], but firm theoretical support for such a conclusion was lacking. With the FLAPW method [Wimmer, Krakauer, Weinert, Freeman, Phys. Rev. B 24, 864 (1981)] we calculated the electronic structure and dielectric function of alpha-quartz and obtained the interaction potential with a Ps atom on its surface. We show that there is indeed a bound state with an energy of 0.14 eV, which is reasonably close to the experimental estimates of 0.14 - 0.17 eV. A brief energy analysis in terms of the Langmuir-Hinshelwood mechanism further shows that the formation of a Ps2 molecule at quartz surface would be possible.
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Electronic Structure Modeling of Heterogeneous Catalysis
9:00 AM-12:00 PM, Sunday, August 19, 2007 BCEC -- 152, Oral
Division of Colloid & Surface Chemistry |