Origin of Anomalously Long Interatomic Distances in Suspended Gold Chains

Abstract

The discovery of long bonds in gold atom chains has represented a challenge for physical interpretation. In fact, interatomic distances frequently attain 3.0-3.6Å values and, distances as large as 5.0 A may be seldom observed. Here, we studied gold chains by transmission electron microscopy and performed theoretical calculations using cluster ab initio density functional formalism. We show that the insertion of two carbon atoms is required to account for the longest bonds, while distances above 3Å may be due to a mixture of clean and one C atom contaminated bonds.

Role of structural evolution in the quantum conductance behavior of gold nanowires during stretching

“…For this purpose, consider the following gold ATC's in the [100] direction: a chain of 2 suspended gold atoms between two [100] tips (Au-Au-Au-Au, four Au atoms forming the narrowest region), as well as the contaminated Au-C-Au-Au chain. The assumed distance separating C and Au atoms is 1.8Å, 32 whereas the AuAu distance is taken to be 2.88Å. Calculations of the conductance produced for the 2 cases are illustrated in Fig.…”

Carbon Nanotube Electron Windmills: A Novel Design for Nanomotors

“…2c show the values of v (6,4) x (q, k y (q, E))/v F for right-moving channels. (for comparison, the blue curves show Fig.…”

“…These structures possess novel electrical properties [4] and extremely low inter-shell friction [5]. The latter discovery led to the idea of CNT nanomechanical oscillators [5], [6], [7], [8], [9] with gigahertz operation frequencies, which is beyond the reach of MEMS oscillators [10]. The ultra-low inter-shell friction in MWCNTs also underpins recently-developed CNT-based nanomotors [11], [12], which involve a MWCNT whose outer shell is clamped to two metallic anchor pads and whose inner shell (or shells) is free to rotate or oscillate.…”

“…2, it is also of interest to ask if F motor can overcome the dynamical friction between the two CNTs [15], [16], [17]. For a spinning CNT with carbon atoms of mass m c moving with a tangential velocity v c , the dynamical friction force per carbon atom is [17] ∞ (E) of equation (12), which is proportional to the total tangential velocity carried by all right-moving channels of energy E in an infinite (6,4) This demonstration that an "electron wind" can cause a chiral "CNT windmill" to rotate, could lead to range of applications [18]. By analogy with the occurrence of spin torques in magnetic point contacts and tunnel junctions [19], [20], which have applications in nanoscale magnetic memory devices, one expects CNT windmills to have nanoscale memory applications.…”

Ab initio calculation of stable structures of a Na atomic chain under bias voltages

“…On the other hand, all of the reported theoretical calculations so far, which adopted various methods, suggest that the Au chain breaks before reaching such suspended geometries [3 -6]. To explain the experimental observation, a few explanations have been proposed, such as that some of atoms in the chain is spinning [4], and that lighter atoms are inserted between Au atoms [7]. Even among experiments there exists a discrepancy: Kizuka et al [8] reported similar experiments as those of Ohnishi et al, but in his experiments the Au -Au interatomic distance was much shorter and the conductance of single atomic chain was measured to be zero.…”