乙腈、苯基氰在Cu(111)与Pd(100)表面上的吸附与反应

用高分辨电子能量损失谱(HREELS~*)对CH_3CN(乙腈)及C_6H_5CN(苯基氰)在清洁与氧覆盖的Cu(111)及Pd(100)表面上的吸附及其反应进行了研究。从198 K时CH_3CN吸附在Cu(111)及Pd(100)表面上的高分辨电子能量损失谱(HREELS)中观察到v(C≡N)几乎消失, 并在195 meV处出现一个较弱的v(C=N)谱带, 表明CH_3CN在吸附过程中C≡N再杂化为C=N,C,N原子分别与金属表面原子键合并C=N平行于表面。从198 K时C_6H_5CN在Pd(100)及Cu(111)上的HREELS表明C_6H_5CN的环平面与CN平行于金属表面。在185K时C_6H_5CN在氧覆盖的Pd(100)表面上的HREELS与其在清洁表面上的相似。并未观察到覆盖氧增强了C_6H_5CN在Pd(100)上的吸附及其它效应。C_6H_5CN吸附在氧覆盖的Cu(111)表面上产生了C_6H_5CNO的特征谱带。

THE ADSORPTION AND REACTION OF ACETONITRILE AND BENZONITRILE ON Cu(111) AND Pd(100)

Adsorption and reaction of acetonitrile (CH_3CN) and benzonitrile (C_6H_5CN) on clean and oxygen covered Cu(111) and Pd(100) surface have been studied by HREELS. At 198 K the CH_3CN molecule rehybridized and chemisorbed on Cu(111) and Pd(100) by di-σ-bonds with carbon and nitrogen atom parallelly to the surface. The chemisorbed species, CH_3-C=N, showing a week loss at 196 meV. The HREEL spectra of C_6H_5CN adsorbed on Pd(100) and Cu(111) are indicative of molecularly adsorbed C_6H_5CN, with the ring plane and the CN group parallelled to the surface at 198 K. The preadsorption of oxygen enhancing the adsorption of CH_3CN and C_6H_5CN on Pd(100) surface was not found. The adsorption of C_6H_5CN on oxygen covered Cu(111) surface results in species with a strong mode at 173 meV, suggesting an N-bonded oxide (—C=N=O). Similar reaction with CH_3CN is supposed.