Activated conduction in microscopic molecular junctions

被引:96
作者
Segal, D
Nitzan, A
Ratner, M [1 ]
Davis, WB
机构
[1] Northwestern Univ, Dept Chem, Evanston, IL 60908 USA
[2] Tel Aviv Univ, Sch Chem, Sackler Fac Sci, IL-69978 Tel Aviv, Israel
关键词
D O I
10.1021/jp994296a
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We analyze the connection between the electron transfer (ET) rate through a given molecular bridge, and the conduction of a junction based on the same bridge between two metals. The Landauer relation between the conduction of a junction and its transmission properties is generalized to yield a relation between conduction and ET rate, including transfer processes dominated by thermal activation. The relation between the orders of magnitude of these observables involves an additional length parameter of the order of the range of the donor wave function. We find that the functional dependence of these observables on the bridge length (N) and on the temperature (T) changes from the exponential and temperature independent, exp(-beta N) for small N, to algebraic and thermally activated form, (alpha(1) + alpha(2)/N)(-1) exp(-Delta E/k(B)T), as N increases. An intermediate range of apparent independence on N exists if alpha(1) much greater than alpha(2). This behavior is the analogue to the quantum Kramers (barrier crossing) problem, analyzed with respect to the barrier length.
引用
收藏
页码:2790 / 2793
页数:4
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