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Synthesis, Characterization, and Reactivity of Ethynyl- and Propynyl-Terminated Si(111) Surfaces

Plymale, Noah T. and Kim, Youn-Geun and Soriaga, Manuel P. and Brunschwig, Bruce S. and Lewis, Nathan S. (2015) Synthesis, Characterization, and Reactivity of Ethynyl- and Propynyl-Terminated Si(111) Surfaces. Journal of Physical Chemistry C, 119 (34). pp. 19847-19862. ISSN 1932-7447. doi:10.1021/acs.jpcc.5b05028.

[img] PDF (Details on the preparation of H–Si(111), Cl–Si(111), and Br–Si(111) surfaces, detailed descriptions of the instrumentation for collection of FTIR, XPS, and SRV data, details on the XPS and SRV data analysis, and supporting figures and table) - Supplemental Material
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Ethynyl- and propynyl-terminated Si(111) surfaces synthesized using a two-step halogenation/alkylation method have been characterized by transmission infrared spectroscopy (TIRS), high-resolution electron energy-loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), atomic-force microscopy (AFM), electrochemical scanning–tunneling microscopy (EC-STM) and measurements of surface recombination velocities (S). For the ethynyl-terminated Si(111) surface, TIRS revealed signals corresponding to ethynyl ≡C–H and C≡C stretching oriented perpendicular to the surface, HREELS revealed a Si–C stretching signal, and XPS data showed the presence of C bound to Si with a fractional monolayer (ML) coverage (Φ) of Φ_(Si–CCH) = 0.63 ± 0.08 ML. The ethynyl-terminated surfaces were also partially terminated by Si–OH groups (Φ_(Si–OH) = 0.35 ± 0.03 ML) with limited formation of Si^(3+) and Si^(4+) oxides. For the propynyl-terminated Si(111) surface, TIRS revealed the presence of a (C–H)CH_3 symmetric bending, or “umbrella,” peak oriented perpendicular to the surface, while HREELS revealed signals corresponding to Si–C and C≡C stretching, and XPS showed C bound to Si with Φ_(Si–CCCH_3) = 1.05 ± 0.06 ML. The LEED patterns were consistent with a (1 × 1) surface unit cell for both surfaces, but room-temperature EC-STM indicated that the surfaces did not exhibit long-range ordering. HCC–Si(111) and CH_3CC–Si(111) surfaces yielded S values of (3.5 ± 0.1) × 10^3 and (5 ± 1) × 10^2 cm s^(–1), respectively, after 581 h exposure to air. These observations are consistent with the covalent binding of ethynyl and propynyl groups, respectively, to the Si(111) surface.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Plymale, Noah T.0000-0003-2564-8009
Kim, Youn-Geun0000-0002-5936-6520
Soriaga, Manuel P.0000-0002-0077-6226
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2015 American Chemical Society. Received: May 26, 2015, Revised: July 7, 2015, Publication Date (Web): July 10, 2015. We acknowledge the National Science Foundation Grant No. CHE-1214152 and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology for support. N.T.P. acknowledges support from the NSF for a Graduate Research Fellowship. Support for Y.-G.K. and M.P.S. to perform the EC-STM experiments was provided by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We thank Dr. Leslie E. O’Leary, Dr. Ronald L. Grimm, and Mr. Christopher W. Roske for helpful discussions. The authors declare no competing financial interest.
Group:Kavli Nanoscience Institute, JCAP
Funding AgencyGrant Number
Caltech Beckman InstituteUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Joint Center for Artificial Photosynthesis (JCAP)UNSPECIFIED
Department of Energy (DOE)DE-SC0004993
Issue or Number:34
Record Number:CaltechAUTHORS:20150825-113614153
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Official Citation:Synthesis, Characterization, and Reactivity of Ethynyl- and Propynyl-Terminated Si(111) Surfaces Noah T. Plymale, Youn-Geun Kim, Manuel P. Soriaga, Bruce S. Brunschwig, and Nathan S. Lewis The Journal of Physical Chemistry C 2015 119 (34), 19847-19862 DOI: 10.1021/acs.jpcc.5b05028
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59887
Deposited By: George Porter
Deposited On:25 Aug 2015 20:38
Last Modified:10 Nov 2021 22:26

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