北京大学电分析课件探针显微镜及其应elect8a.ppt

Schematic representation of the principles of SECM with micro-ITIES SECM image obtained using a micro-ITIES probe (5-?m tip) . Substrate was silicon with parallel platinum bands. J.Electroanal.Chem., 1997, 439, p137-143 Positive feedback Negative Feedback Approach a big L/L interface Approach a solid substrate RG = Rg/a Bard et al. have developed the theory for RG ? 10 cases. However, for micropipettes as the tips for SECM, the RGs are usually ? 2. Using software package PDEase (SPDE, Inc.), we have solved the theoretical i - d curves for RG ? 2. J.Phys.Chem B., 1998, 102, p9915-9921 RG = Rg/a =b/a L = d/a Aqueous Phase Organic Phase Current-distance curves obtained with different concentrations of TEACl in the aqueous phase. (1)0, (2)0.4, and (3)10 mM. TEA+ (w) = TEA+(o) RG =1.1 Constant height mode gray scale images of pores in polycarbonate membrane TCNQ + Fe(CN)64- = TCNQ.- + Fe(CN)63- Fe(CN)63- (w) + e = Fe(CN)64-(w) E1o =0.41V vs SHE TCNQ (o) + e = TCNQ.-(o) E2o =0.22V vs SHE ?ow? = ?ow?o +(RT/nF)ln[ai(o)/ai(w)] ?ow? E2o - E1o (-190mV) ?ow?TBA+o = -225mV Reverse Electron Transfer Reactions Approach curve for the system: H2O, TPAsCl, 1mM Fe(CN)63- || DCE, 1mM TPAsTPB, 10mM TCNQ; showing the electron transfer driven by the phase transfer catalyst TPAs+ .From top to bottom, the experent curve are shown for Kp=10,5,2,1 . A:TPAs system. B: TBA system. Dependence of the effective ET rate constant on concentration of TCNQ in DCE. The k value were used to fitthe approach curev with a=10?m and . From top to bottom the Kp value was shown for 10,5,2. A:TPAs syetem. B:TBA system. Dependence of the effective ET rate constant on potential drop across the ITIES. A:TPAs. B:TBA. SECM Studies of ET Reactions across Ice/Liquid Interface * College of Chemistry and Molecular Engineering Peking University Email: yhshao@chem.pku.edu.cn Phone:Scanning Probing Microscopy (SPM) Yuanhua Shao 扫描探针显微镜及其应用 Outline: 1. Introduction 2. Instrument