Molecular Motion Induced by Multivibronic Excitation on Semiconductor Surface
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- 作者：Tatsuya Momose ; Ken-ichi Shudo ; Hannes Raebiger ; Shin-ya Ohno ; Takeshi Kitajima ; Masanobu Uchiyama ; Takanori Suzuki ; Masatoshi Tanaka
- 刊名：Journal of Physical Chemistry C
- 出版年：2014
- 出版时间：January 23, 2014
- 年：2014
- 卷：118
- 期：3
- 页码：1554-1559
- 全文大小：345K
- ISSN：1932-7455
文摘
A low-temperature observation with a scanning tunneling microscope (STM) of CO adsorbed on the Si(001) surface shows a peculiar change in adsorbate structure. Only after repeated scanning, approximately half of the adsorbed CO become visible as bright spots due to an irreversible lateral motion of the CO molecules, while at first the adsorbed CO is invisible to STM. The reaction rate of this motion shows hyperlinear dependence on the tunneling current. This implies that the adsorbate displacement is caused by multiple excitations of adsorbate vibronic modes, which is a mechanism thus far observed only at metal surfaces. We observe an activation barrier of 0.11 eV for the irreversible motion of CO, in agreement with the adiabatic potential obtained from first-principles calculation. The atomic-scale local heating is site-specific due to highly efficient inelastic scattering by charging of a surface-localized midgap state induced by the STM tip鈥搒ample bias voltage.