AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP40
The Interactions of Azomethane and Methyl Radical with Cu(111)

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: P. Chuang, National Taiwan University, Taiwan
Authors: P. Chuang, National Taiwan University, Taiwan
Y.L. Chan, Academia Sinica, Taiwan
C.H. Chuang, National Central University, Taiwan
S.-H. Chien, National Taiwan University, Taiwan
T.J. Chuang, National Taiwan University, Taiwan
Correspondent: Click to Email
We have employed TPD, XPS, LEED and HREELS to investigate the interactions of CH@sub 3@ radicals and CH@sub 3@N@sub 2@CH@sub 3@ molecules with Cu(111). The subject is of interest@footnote@ due to the importance of the radical in many heterogeneous reactions involving hydrocarbons. It is found that distinctive adsorption states exist for azomethane on Cu at 90K depending on surface coverage. Molecular desorption is detected at 205K, 145K and 120K corresponding to the first chemisorbed layer, the second layer and the bulk-like multilayer, respectively. Both first-order and zero-order desorption kinetics are observed. Methyl radicals can be chemisorbed on Cu(111) at 300K showing partial decomposition to CH@sub 2@(ads) and H(ads), mediated possibly by defect sites. CH@sub 3@ thermal desorption signals exhibit two channels at about 360K and 440K, corresponding to the second-order and the first-order desorption kinetics. The behavior is closely related to H and CH@sub 3@ coadsorption and reaction during the desorption process. The results of TPD, XPS and HREELS are correlated with each other and compared with previous work. @FootnoteText@ @footnote 1@T.J. Chuang, Y.L. Chan, P. Chuang and R. Klauser, J. Electr. Spectr. Relat. Phenom. 98-99, 149 (1999).