Evidence for a Through-Space Pathway for Electron Transfer from Quantum Dots to Carboxylate-Functionalized Viologens

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• 作者：Adam J. Morris-Cohen ; Mark D. Peterson ; Matthew T. Frederick ; Judith M. Kamm ; Emily A. Weiss
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：October 4, 2012
• 年：2012
• 卷：3
• 期：19
• 页码：2840-2844
• 全文大小：249K
• 年卷期：v.3,no.19(October 4, 2012)
• ISSN：1948-7185

文摘

Ultrafast transient absorption measurements reveal that the rate constant for photoinduced electron transfer (PET) from colloidal CdS quantum dots (QDs) to alkylcarboxylate-functionalized viologens is independent of the number of methylene groups in the alkyl chain (n). The rate constant for PET is (1.2 卤 0.3) 脳 10¹⁰ s^鈥? for n = 1, 2, and 3, and for n = 0 (methylviologen). The insensitivity of the electron transfer rate constant to the length of the functional groups on the viologen suggests that a 鈥渢hrough-space鈥?pathway, where the electron bypasses the alkylcarboxylate and tunnels instead through only the orbitals of the QD and of the bipyridinium core, is the dominant PET pathway.

Keywords:

transient absorption; adsorption geometry; electronic coupling; electron tunneling; nanocrystal