Paulius D, Torres D, Illas F, Archibald W E
College of Science and Mathematics, University of the Virgin Islands, The Virgin Islands, USA.
Phys Chem Chem Phys. 2014 Nov 14;16(42):23067-73. doi: 10.1039/c4cp03074e.
Self-assembled monolayers on Au(111) have outstanding chemical, electrical, and optical properties, and Au adatoms seem to play a key role in these properties. Still, the fundamental understanding of adatom transport inside the self-assembled structure is very thin. In this paper we use first-principles calculations to reveal new details about the migration mechanism of Au adatoms in the presence of a CH3S self-assembled structure on Au(111). We study the inclusion of Au adatoms inside a well-packed (√3 × √3)-R30°-CH3S self-assembled lattice and present atomistic models supporting adatom migration by means of a hopping mechanism between pairs of CH3S species. Our calculations reveal that the transport of Au adatoms is slowed down inside the molecular network where the kinetic barrier for adatom migration is larger than on the clean Au surface. We attribute the hindered mobility of Au adatoms to the fact that adatom transport involves the breaking and making of Au-S bonds. Our results form a basis for further understanding the role played by defect transport in the properties of molecular assemblies.
在Au(111)表面的自组装单分子层具有出色的化学、电学和光学性质，金吸附原子似乎在这些性质中起着关键作用。然而，对于自组装结构内部吸附原子传输的基本理解仍然非常有限。在本文中，我们使用第一性原理计算来揭示在Au(111)上存在CH3S自组装结构时金吸附原子迁移机制的新细节。我们研究了金吸附原子包含在紧密堆积的(√3 × √3)-R30°-CH3S自组装晶格中的情况，并通过CH3S物种对之间的跳跃机制提出了支持吸附原子迁移的原子模型。我们的计算表明，在分子网络内部金吸附原子的传输速度减慢，其中吸附原子迁移的动力学势垒大于在清洁Au表面上的势垒。我们将金吸附原子迁移受阻归因于吸附原子传输涉及Au-S键的断裂和形成这一事实。我们的结果为进一步理解缺陷传输在分子组装性质中所起的作用奠定了基础。
