Dynamic Strength of the Silicon-Carbon Bond Observed over Three Decades of Force-Loading Rates

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• 作者：Sebastian W. Schmidt ; Martin K. Beyer ; Hauke Clausen-Schaumann
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：March 19, 2008
• 年：2008
• 卷：130
• 期：11
• 页码：3664 - 3668
• 全文大小：101K
• 年卷期：v.130,no.11(March 19, 2008)
• ISSN：1520-5126

文摘

The mechanical strength of individual Si-C bonds was determined as a function of the appliedforce-loading rate by dynamic single-molecule force spectroscopy, using an atomic force microscope. Theapplied force-loading rates ranged from 0.5 to 267 nN/s, spanning 3 orders of magnitude. As predicted byArrhenius kinetics models, a logarithmic increase of the bond rupture force with increasing force-loadingrate was observed, with average rupture forces ranging from 1.1 nN for 0.5 nN/s to 1.8 nN for 267 nN/s.Three different theoretical models, all based on Arrhenius kinetics and analytic forms of the binding potential,were used to analyze the experimental data and to extract the parameters f_max and D_e of the binding potential,together with the Arrhenius A-factor. All three models well reproduced the experimental data, includingstatistical scattering; nevertheless, the three free parameters allow so much flexibility that they cannot beextracted unambiguously from the experimental data. Successful fits with a Morse potential were achievedwith f_max = 2.0-4.8 nN and D_e = 76-87 kJ/mol, with the Arrhenius A-factor covering 2.45 × 10^-10-3 × 10^-5 s^-1, respectively. The Morse potential parameters and A-factor taken from gas-phase densityfunctional calculations, on the other hand, did not reproduce the experimental forces and force-loadingrate dependence.