Adsorption of Phenylacetylene on Si(100)-2 × 1: Kinetics and Structure of the Adlayer

详细信息    查看全文

• 作者：Olivier Pluchery ; Romain Coustel ; Nadine Witkowski ; Yves Borensztein
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：November 16, 2006
• 年：2006
• 卷：110
• 期：45
• 页码：22635 - 22643
• 全文大小：499K
• 年卷期：v.110,no.45(November 16, 2006)
• ISSN：1520-5207

文摘

Direct adsorption of phenylacetylene on clean silicon surface Si(100)-2 × 1 is studied in ultrahigh vacuum(UHV). The combination of scanning tunnel microscopy (STM) and surface differential reflectance spectroscopy(SDRS) with Monte Carlo calculations are put together to draw a realistic kinetic model of the evolution ofthe surface coverage as a function of the molecular exposure. STM images of weakly covered surfaces provideevidence of two very distinct adsorption geometries for phenylacetylene, with slightly different initial stickingprobabilities. One configuration is detected with STM as a bright spot that occupies two dangling bonds ofa single dimer, whereas the other configuration occupies three dangling bonds of adjacent dimers. These dataare used to implement a Monte Carlo model which further serves to design an accurate kinetic model. Theresulting evolution toward saturation is compared to the optical data from surface differential reflectancespectroscopy (SDRS). SDRS is an in situ technique that monitors the exact proportion of affected adsorptionsites and therefore gives access to the surface coverage which is evaluated at 0.65. We investigate the effectof surface temperature on this adsorption mechanism and show that it has no major effect either on kineticsor on structure, unless it passes the threshold of dissociation measured at ca. 200 C. This offers a comprehensiveimage of the whole adsorption process of phenylacetylene from initial up to complete saturation.