镧薄膜表面的激活化学吸附研究  

THE STUDY OF ACTIVATED CHEMISORPTION ON SURFACE OF La THIN FILM

作　　者：邵淑敏[1] 王倩[1] 宋健平 李胜林[1] 周志强[1] 席光康[1] 

机构地区：[1]南开大学电子科学系,天津300071

出　　处：《真空科学与技术》1995年第1期23-30,共8页Vacuum Science and Technology

基　　金：国家自然科学基金

摘　　要：用俄歇谱及分子束技术就地与非就地研究了蒸发稀土金属镧薄膜的表面特性。一种情况是在镀膜机内制作镧薄膜，从镀膜机中取出，暴露在大气中，然后放入超高真空室内进行研究。另一种情况是La薄膜在超高真空室内制备并就地研究。结果表明，两种情况下获得的两样品的俄歇谱图不同。样品1的俄歇谐相当于表面组分主要为La（OH）3，它是由空气中的氧和水汽与表面作用形成的。样品2的俄歇谱相当于表面主要组分为La。少量的La（OH）3是La和超高真空室内的残余H2O作用的结果。用分子束技术对CH4在两样品表面的激活化学吸附特性进行了研究。实验发现初始粘着几率S0强烈地依赖于入射分子束的平动能，并以En＝Ecos2θi表征。在两种情况下都有初始粘着几率随平动能增大而线性增加。当样品表面温度由500K升至700K时，两样品的阈值能和活化能都不随表面温度变化，在相同气体作用下，阈值能和活化能仅由样品本身的结构和性质决定。The surface characteristics of evaporated rare-earth metal La thin film were studied by ex-situ and in-situ AES and molecular beam technique. In case 1,the La thin film was prepared in the vacuum system, then taken out of the system exposing under atmospheric condition and finally put into the UHV chamber to be studied. In case 2,the La thin film was prepared and in-situ studied in the UHV chamber. Auger electron spetroscopic data in both cases were obtained showing different surface comPOsition. The surface compostions observed by ex-situ AES studies correspond to mainly La(OH), which can be attributed to a surface modification by O2 and water vapor from the ambient atmosphere. The in-situ AES studies revealed the suffece comPOSition of La. The activated chmisorPtion of CH4 on La thin film was studied in both cases using molecular beam 'techniques. After surface cleaning treatment of samples, chem isorption probability were measured as a function of translational kinetic energy. The initial sticking probability was found to depend strongly on the incident kintic energy E,scaling En=Ecos2θi. The initial sticking probability increases linearly with the translational kinetic energy of the incident molecular beam but the threshold values and the activeted energies were not changed when the surface temperetures were increased from 500K to 700K.

关 键 词：镧薄膜 薄膜表面 俄歇谱 激活化学吸附 

分 类 号：O614.331[理学—无机化学] TG111.7[理学—化学]