Chemisorption of 1,1-dichloroethene on the Si(111)-7 x 7 surface

Chemisorption of 1,1-dichloroethene (Cl2C=CH2) to a Si(111)-7 x 7 surface was studied by means of X-ray photoelectron spectroscopy using synchrotron radiation, recording chlorine 2p and carbon Is spectra. For carbon Is, spectral assignment of the chemisorbed species is based on quantum chemical calculations of chemical shifts in model compounds. The results confirm the identity of covalently bonded l-chlorovinyl (-CCl=CH2) and vinylidene ( C=CH2) adspecies. Upon chemisorption at room temperature it was found that about one-third of the molecules break one C-Cl bond while about two-thirds of the adsorbates break two C-Cl bonds. We do not, however, find evidence for isomerization of C=CH2 to di-bonded vinylene (-CH=CH-). (c) 2007 Elsevier B.V. All rights reserved.