Department of Chemical Physics, Weizmann Institute of Science , Rehovot, 76100 Israel.
ACS Nano. 2013 Dec 23;7(12):11147-55. doi: 10.1021/nn404873x. Epub 2013 Nov 27.
The effect of electron-vibration interaction in atomic-scale junctions with a single conduction channel was widely investigated both theoretically and experimentally. However, the more general case of junctions with several conduction channels has received very little attention. Here we study electron-vibration interaction in multichannel molecular junctions, formed by introduction of either benzene or carbon dioxide between platinum electrodes. By combining shot noise and differential conductance measurements, we analyze the effect of vibration activation on conductance in view of the distribution of conduction channels. Based on the shift of vibration energy while the junction is stretched, we identify vibration modes with transverse and longitudinal symmetry. The detection of different vibration modes is ascribed to efficient vibration coupling to different conduction channels according to symmetry considerations. While most of our observations can be explained in view of the theoretical models for a single conduction channel, the appearance of conductance enhancement, induced by electron-vibration interaction, at high conductance values indicates either unexpected high electron-vibration coupling or interchannel scattering.
电子-振动相互作用在具有单个传导通道的原子尺度结中的影响已经在理论和实验上得到了广泛的研究。然而，具有多个传导通道的更一般情况却很少受到关注。在这里，我们研究了由铂电极之间引入苯或二氧化碳形成的多通道分子结中的电子-振动相互作用。通过结合噪声和微分电导测量，我们根据传导通道的分布来分析振动激活对电导的影响。基于结拉伸时振动能的位移，我们根据横向和纵向对称性来识别振动模式。根据对称性考虑，不同振动模式的检测归因于与不同传导通道的有效振动耦合。虽然我们的大多数观察结果可以根据单个传导通道的理论模型来解释，但在高电导值下出现的由电子-振动相互作用引起的电导增强表明，要么是出乎意料的高电子-振动耦合，要么是通道间散射。
