Tetra-σ attachment of allyl cyanide onSi(111)−7×7

Abstract

The investigation of allyl cyanide adsorption on Si(111)-7ϫ7 using high-resolution electron-energy-loss spectroscopy ͑HREELS͒, x-ray photoelectron spectroscopy ͑XPS͒, and ultraviolet photoelectron spectroscopy ͑UPS͒ reveals a tetra-binding mode through two ͓2ϩ2͔-like cycloaddition reactions. The HREELS spectra of chemisorbed monolayer show the absence of CvC, CwN, and C(sp 2 )uH stretching modes coupled with the appearance of CvN stretching mode at ϳ1590 cm Ϫ1 , demonstrating that both the CvC and CwN of allyl cyanide directly participate in binding with the surface to form C-C and CvN bonds, respectively. This binding configuration was further confirmed in our XPS and UPS studies. The imine-containing skeleton formed on the surface can possibly be employed as a molecular template for a further modification of Si surfaces and syntheses in vacuum.

Dissociation and [2+2]-like Cycloaddition of Unsaturated Chain Amines on Si(111)-7×7

“…Compared to the spectrum of physisorbed molecules, the major spectroscopic change upon chemisorption is the disappearance of C sp 2 −H (3082 cm -1 ) and CC (1648 cm -1 ) stretching vibrations, indicating the direct involvement of CC in the surface reaction. Moreover, a new intensity at 501 cm -1 is ascribed to the Si−C stretching, consistent with the previous studies on the binding of organic molecules on silicon surfaces through the Si−C linkages. − These results clearly demonstrate that DMAA undergoes a [2+2]-like cycloaddition via the CC group to form new Si−C bonds at the DMAA/Si(111)-7×7 interface, in a similar way of ethylene binding to the Si surface. − The detailed assignments for the vibrational features of chemisorbed molecules are summarized in Table .…”

“…Figures a and a show the N(1s) and C(1s) photoemission spectra of physisorbed DMAA [C 1 H 2 C 2 H−C 3 H 2 N(C 4,5 H 3 ) 2 ] on Si(111)-7×7, obtained upon exposing the Si sample to 15.0 L of DMAA at 110 K. The physisorbed molecules yield one N(1s) dominant peak centered at 400.1 eV, consistent with the data obtained for condensed N -containing compounds. ,,, In Figure a, two fitted C(1s) intensities are located at 285.3 and 286.5 eV, with an area ratio of ∼2:3. The peak at 285.3 eV is related to the sp 2 carbon atoms of C 1 H 2 C 2 H− ,,, and the other at 286.5 eV can be assigned to C 3 , C 4 , and C 5 , which are linked to the N atom directly.…”

Chemical manipulation of multifunctional hydrocarbons on silicon surfaces

“…In the example of diacetylene, the reaction of one C≡C group led to the formation of surface species in such a configuration that any further transformation of the other C≡C group is nearly impossible; however, if a longer linker is used to connect two unsaturated groups, for example in the studies of allyl cyanide (CH 2 =CH-CH 2 -C≡N) [311], both of them could easily react with the surface. The combination of HREELS, XPS, and UPS was used to determine that upon chemisorption at room temperature, both the C=C and C≡N groups of allyl cyanide react with the Si(111)-7×7 substrate to form corresponding C-C and C=N entities [311].…”

“…The combination of HREELS, XPS, and UPS was used to determine that upon chemisorption at room temperature, both the C=C and C≡N groups of allyl cyanide react with the Si(111)-7×7 substrate to form corresponding C-C and C=N entities [311].…”

Multiple configurations ofN-methylpyrrole binding onSi(111)−7×7

“…The great difference in electron density and the spatial separation ͑ϳ4.5 Å͒ between the adjacent adatom and rest atom make them an efficient di-radical in the covalent attachment of unsaturated organic molecules. [3][4][5][6] Earlier studies in this area mainly focused on the binding of ethylene, 9,10 acetylene, [11][12][13] benzene, 14,15 and chlorobenzene. 16,17 Experimental results and theoretical calculations suggest the ͓2ϩ2͔-like cycloaddition mechanism 9 for molecules containing one CvC bond [10][11][12][13] and ͓4ϩ2͔-like cycloaddition pathway 14 for dienelike molecules.…”