ScholarWorks@숙명여자대학교

초록

The atomic structures of clean Pd(001) and Pd(001) with one monolayer of absorbed hydrogen are investigated by using I-V (diffraction beam intensity versus beam energy) analyses of low energy electron diffraction (LEED). Clean Pd(001) shows an almost bulk-terminated structure with little structural relaxation near the surface region while hydrogen covered Pd(001) shows a large expansion by +4.7 % of the interlayer distance between the two layers adjacent to the surface. The observed atomic structures of the clean and the hydrogen-covered Pd(001) are in excellent agreement with those predicted by recent first-principles calculations. We also examine the development of the atomic structure of Pd(001) with increasing amount of adsorbed hydrogen and find that as the hydrogen coverage increases, so does the interlayer spacing between the two layers near to the surface. Such an observation strongly suggests that the previously reported observation of expanded interlayer spacing of clean Pd(001) originates from hydrogen contamination of Pd(001).

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