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:
<a id="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=transient+absorption&qsSearchArea=searchText">transient absorption; <a id="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=adsorption+geometry&qsSearchArea=searchText">adsorption geometry; <a id="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=electronic+coupling&qsSearchArea=searchText">electronic coupling; <a id="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=electron+tunneling&qsSearchArea=searchText">electron tunneling; <a id="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=nanocrystal&qsSearchArea=searchText">nanocrystal