Mamatkulov M, Stauffer L, Sonnet Ph, Mayne A J, Comtet G, Dujardin G
Laboratoire de Physique et de Spectroscopie Electronique, CNRS UMR 7014, Universite de Haute Alsace, 4 rue des Freres Lumiere, 68093 Mulhouse, France.
J Chem Phys. 2008 Jun 28;128(24):244710. doi: 10.1063/1.2943680.
We have investigated from a theoretical point of view modifications of the 4,4(')-diacetyl-p-terphenyl molecule chemisorbed on Si(001) induced by the scanning tunneling microscope (STM). In previous experiments, these modifications were observed to occur preferentially at the end of the molecule after a +4.0 V voltage pulse and at the center after a +4.5 V voltage pulse. In the framework of ab initio simulations, we have realized a systematic energetic study of the dissociative chemisorption of one, two, or three phenyl rings of the substituted p-terphenyl molecule. Charge densities were then calculated for the investigated configurations and compared to the STM topographies. Before manipulation with the STM tip, the substituted p-terphenyl molecule is preferentially adsorbed without phenyl ring dissociation, allowing a partial rotation of the central phenyl ring. Our results show that the STM induced modifications observed at the end of the molecule might originate from the dissociation of two phenyl rings (one central and one external ring), while the modifications occurring at the central part of the molecule can be interpreted as a dissociation of the two external rings.
我们从理论角度研究了扫描隧道显微镜（STM）对吸附在Si(001)上的4,4(')-二乙酰基对三联苯分子的修饰作用。在先前的实验中，观察到这些修饰在 +4.0 V电压脉冲后优先发生在分子末端，而在 +4.5 V电压脉冲后优先发生在分子中心。在从头算模拟的框架内，我们对取代对三联苯分子的一个、两个或三个苯环的解离化学吸附进行了系统的能量研究。然后计算了所研究构型的电荷密度，并与STM形貌进行了比较。在用STM针尖进行操纵之前，取代对三联苯分子优先吸附且无苯环解离，允许中心苯环进行部分旋转。我们的结果表明，在分子末端观察到的STM诱导修饰可能源于两个苯环（一个中心环和一个外环）的解离，而在分子中心部分发生的修饰可解释为两个外环的解离。
