N2在Cr(110)表面的强化学吸附与离解

用原子交叠和电子离域-分子轨道(ASED-MO)方法研究N₂在Cr(110)面的化学吸附过程。结果表明,N₂平行吸附于Cr(110)面的四度空位,N-N轴平行于110]方向,与传统的σ施予和π弱反键作用不同,N₂在Cr(110)面平行吸附时,不仅3σ_g而且1π_μ分别向衬底施予0.97和0.54个电子,同时1π_g的反向键合增加到1.83个电子,这导致平行吸附比垂直吸附具有更低 关键词：

STRONG CHEMISORPTION AND DISSOCIATION OF N2 ON Cr(110) SURFACES

An ASED-MO method has been applied to investigate the N₂ chemisorption on Cr(110) surface. The results show that N₂ chemisorbs parallelly on the 4-fold site with N-N axis parallel to 110] direction. Different from the tranditional σ-donation and π weak backbonding concepts, the N₂ chemisorption on Cr(110) has both the 3 σ_g and 1 π_μ donations of 0.97 and 0.54 electrons. At the same time, the backbonding to the 1 π_g orbital increases to 1.83 electrons. Both these factors make the lying-down orientation being favored over the upright orientation. Furthermore, the N-N bond length strenches 17%, the N-N bond order decreases to below 1, and the dissociation barrier is only about 0.15 eV. All the above calculation results are in good agreement with relevant experiments.