Charge-State Dependent Vibrational Relaxation in a Single-Molecule Junction.
Charge-State Dependent Vibrational Relaxation in a Single-Molecule Junction.
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DOI：
10.1103/physrevlett.129.207702
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发表时间：
2022-02
影响因子：
8.6
通讯作者：
X. Bian;Zhixing Chen;Jakub K. Sowa;C. Evangeli;B. Limburg;J. Swett;J. Baugh;G. Briggs;H. Anderson;J. Mol;James O. Thomas
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文献类型：
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作者：
X. Bian;Zhixing Chen;Jakub K. Sowa;C. Evangeli;B. Limburg;J. Swett;J. Baugh;G. Briggs;H. Anderson;J. Mol;James O. Thomas
电子转移过程的结果由电子自由度和振动自由度之间的量子力学相互作用决定。已知非平衡振动动力学可以指导分子系统中的电子转移机制;然而，导致某些模式被推离平衡的分子的结构特征还没有得到很好的理解。在这里，我们报告通过卟啉二聚体分子，弱耦合到石墨烯电极，显示连续的隧道内的库仑阻塞制度的电子传输。的顺序运输是由电流诱导的声子吸收和收益的快速顺序运输通过低能量模式的非平衡振动分布，可能与扭转分子运动。我们证明，这是一个缓慢的振动耗散的实验签名，并获得了8纳秒的振动弛豫时间的下限，一个值依赖于分子的电荷状态。
The outcome of an electron-transfer process is determined by the quantum-mechanical interplay between electronic and vibrational degrees of freedom. Nonequilibrium vibrational dynamics are known to direct electron-transfer mechanisms in molecular systems; however, the structural features of a molecule that lead to certain modes being pushed out of equilibrium are not well understood. Herein, we report on electron transport through a porphyrin dimer molecule, weakly coupled to graphene electrodes, that displays sequential tunneling within the Coulomb-blockade regime. The sequential transport is initiated by current-induced phonon absorption and proceeds by rapid sequential transport via a nonequilibrium vibrational distribution of low-energy modes, likely related to torsional molecular motions. We demonstrate that this is an experimental signature of slow vibrational dissipation, and obtain a lower bound for the vibrational relaxation time of 8 ns, a value dependent on the molecular charge state.