2007 Fiscal Year Final Research Report Summary
Dissipation of translational energy of molecules on surfaces
| Project/Area Number |
18550004
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Tohoku University |
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Principal Investigator |
TAKAOKA Tsuyoshi Tohoku University, Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, lecturer (90261479)
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| Co-Investigator(Kenkyū-buntansha) |
KOMEDA Tadahiro Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, professor (30312234)
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| Project Period (FY) |
2006 – 2007
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| Keywords | solid surfaces / STM / Infrared spectroscopy / chemical reaction / catalytic reaction |
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| Research Abstract |
In 2006, we have performed the experiment about the adsorbate diffusion on solid surfaces by using super sonic molecular beam apparatus combined with ultra high vacuum chamber. From the analysis of the Fourier transformed infrared spectra obtained after a stepped Pt(997) surface was exposed to CO molecules and subsequently to energy-controlled Ne or Ar atoms, the activation energy of the diffusion of CO adsorbed at terrace site and step site were obtained.
In 2007, we examined the mechanism of the relaxation of the translational energy of adsorbates on surfaces during the diffusion process by the use of collision induced diffusion phenomena as follows: After a Pt(997) surface was exposed to CO molecules with a coverage of 0.033 ML, it was exposed to Ne or Ar atoms with a translational energy. If the friction applied to CO molecules at terrace site is low, they can migrate long distances after a collision imparts a sufficiently high kinetic energy. If the friction is large, they will stop immediately after the collision. Then, the friction can be estimated from the distribution of CO molecules after the collision with rare gas atoms. However, since the translational energy of CO molecule and its direction depend on the arrangement of the CO molecule and the rare gas atom upon the collision, we employed molecular dynamics calculation and the calculational results were compared with experimental results. From the comparison, the friction coefficient of CO on the Pt surface was estimated to be 8x10^<12> sec^<-1>.
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