Binding and structure of acetonitrile on Si(111)-7x7

作者：Tao F; Chen XF; Wang ZH; Xu GQ^*

来源：Journal of Physical Chemistry B, 2002, 106(15): 3890-3895.

DOI：10.1021/jp012710c

The covalent binding and structure of acetonitrile on Si(111)-7 x 7 have been investigated to provide information on the interaction of pi electrons of the Cequivalent toN group with the dangling bonds of Si(111)-7 x 7. Vibrational features of chemisorbed acetonitrile and acetonitrile-d(3) unambiguously show the absence of Cequivalent toN stretching mode around 2232 cm(-1) coupled with the appearance of C=N stretching mode at 1663 cm(-1). Both C Is and N Is core levels of chemisorbed acetonitrile display large chemical shifts of 2.2 and 1.3 eV, respectively, compared with those of physisorbed molecules. In addition, the photoemission from pi(CN) was observed to be weakened upon chemisorption. These results clearly suggest that the cyano group directly participates in the interaction with Si surface dangling bonds. Scanning tunneling microscopy images reveal that the cyano groups selectively bind to adatom-rest atom pairs on Si(111)-7 x 7. Density functional theory calculations indicate that the C and N atoms of the cyano group favorably link with the adatom and rest atom, respectively, forming C-Si and N-Si bonds.

• 出版日期2002-4-18