Time-Resolved Synchrotron XPS Monitoring of Irradiation-Induced Nitrobenzene Reduction for Chemical Lithography

详细信息    查看全文

• 作者：K. Roodenko ; M. Gensch ; J. Rappich ; K. Hinrichs ; N. Esser ; R. Hunger
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：July 5, 2007
• 年：2007
• 卷：111
• 期：26
• 页码：7541 - 7549
• 全文大小：391K
• 年卷期：v.111,no.26(July 5, 2007)
• ISSN：1520-5207

文摘

The irradiation-induced reduction of electrochemically grafted nitrobenzene films on Si(111) was monitoredby high-resolution photoelectron spectroscopy. The experiments were performed using synchrotron soft X-rayirradiation at the BESSY II synchrotron facility. The evolution of different chemical species was monitoredas a function of time. Careful fitting of the Si2p, C1s, N1s, and O1s core level spectra allowed us to followthis process in detail and to determine the constants of growth and decay of the specific components. Thechemical changes were caused by the X-ray irradiation-induced secondary electron current through the aryllayer. A minor fraction (~25%) of the initial nitro groups was split off and desorbed. The bulk of the NO₂groups was reduced to species in an amino-like chemical environment. A desorption of carbon fragmentswas not observed, and benzene ring specific shakeup satellites indicated that the aromatic ring structure remainedintact. Irradiation-induced line-shape changes suggest a polymerization via -NH- bridges, which were formedafter the irradiation-induced N-O bond splitting. A significant part of the released oxygen appeared to contributeto an oxidation of the silicon substrate at the Si(111)/benzene interface. The irradiation-induced aryl layermodification can be exploited for chemical lithography (i.e., a lateral structuring of functionalized siliconsurfaces).