Adsorption and desorption of acetylene on Ge(100)Ge(100) 표면 위의 아세틸렌 흡착과 탈착에 관한 연구

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The adsorption and thermal desorption of acetylene on Ge(100) have been studied in ultrahigh vacuum by Auger electron spectroscopy (AES), temperature-programmed desorption (TPD), and low energy electron diffraction (LEED). Acetylene is found to chemisorb and to desorb molecularly on Ge(100) via a mobile precursor in a different way with Si(100) on which chemisorbed acetylene was found to undergo two thermal reactions; a minor pathway (molecular desorption) and a major pathway (dissociation of acetylene). The difference between activation energy for desorption from the precursor and that for reaction from the precursor into the chemisorbed state is found to be ($E_p$ - $E_c$) = 3.6 ± 0.23 kcal/mol. TPD measurements show that two molecular desorption features at all coverages, indicating that at least two adsorption states can be formed. For desorption kinetics, $C_2H_2$ desorption is first order reaction and the activation energies for desorption at saturation coverage are 30.6 kcal/mol for $α_1$ state and 32.9 kcal/mol for $α_2$ state whereas the energy for desorption of acetylene from Si(100) was found to be 46.1 ± 2.0 kcal/mol. The lower desorption activation energy allows $C_2H_2$ to desorb prior to significant dissociation which is a major pathway in desorption from Si(100). The angular distrbution of $C_2H_2$ desorption is peaked at surface normal. The results are discussed on the basis of bonding geometry. From the retention of 2$\times$1 LEED patterns as increasing the $C_2H_2$ coverage, it is also concluded that $C_2H_2$ on Ge(100) chemisorbs molecularly.
Advisors
Kim, Se-Hunresearcher김세훈researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2001
Identifier
165999/325007 / 000993116
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 화학과, 2001.2, [ ix, 51 p. ]

Keywords

desorption mechanism; adsorption mechanism; acetylene; Ge(100); surface reaction; 표면위의 반응; 탈착 메커니즘; 흡착 메커니즘; 아세틸렌; Ge(100)

URI
http://hdl.handle.net/10203/31889
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=165999&flag=dissertation
Appears in Collection
CH-Theses_Master(석사논문)
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