Stabilization of the Si(553) surface by Au adsorption results in two different atomically defined chain types, one of Au atoms and one of Si. At low temperature these chains develop two-and threefold periodicity, respectively, previously attributed to Peierls instabilities. Here we report evidence from scanning tunneling microscopy that rules out this interpretation. The ×3 superstructure of the Si chains vanishes for low tunneling bias, i.e., close the Fermi level. In addition, the Au chains remain metallic despite their period doubling. Both observations are inconsistent with a Peierls mechanism. On the contrary, our results are in excellent, detailed agreement with the Si(553)-Au ground state predicted by density-functional theory, where the ×2 periodicity of the Au chain is an inherent structural feature and every third Si atom is spin-polarized.Atoms can form chain-like architectures by selfassembly on various semiconductor surfaces. Such chains have been widely studied because they may offer physical realizations of various one-dimensional (1D) electronic ground states -Peierls instabilities (i.e., charge density waves, CDW) [1] or Tomonaga-Luttinger liquids [2] -in which Coulomb interactions are dominant. An equally interesting scenario arises if the electron's spin degree of freedom is important or even dominant. For example, a proposal was made [3] to use atomic chains as a spin shift register, where spin encodes the information. Recent research has focused on spin alignment in 2D atom lattices on semiconductor substrates [4,5]. The fate of spin ordering in 1D chains on surfaces, however, has remained less explored experimentally.The variability offered by chains formed on different high index Si surfaces allows us to investigate this interplay of charge, spin, and lattice in a family of related structures. Specific representatives include the chain structures stabilized by Au on Si(557)-Au and Si(553)-Au. These systems carry Au-induced metallic electron bands as seen in photoemission [6]. In Si(553)-Au -the focus of the present work -the situation is particularly complex. The structure as derived from x-ray diffraction [7] and density-functional theory (DFT) [8,9] exhibits a dimerized double-strand Au chain, in contrast to the single Au row in Si(557)-Au. As an additional key characteristic of both variants, there is a second type of chain located at the terrace edge, formed by Si atoms which are arranged in a graphene-like honeycomb chain [8,9].In two seminal papers, changes in the periodicity of both types of chains upon cooling were observed by scanning tunneling microscopy (STM) [10,11], leading to two-and threefold patterns for the Au and the Si chain, respectively. Moreover, from photoemission data [11] a temperature-dependent gap opening was inferred. These observations for Si(553)-Au were interpreted as Peierls instabilities, driven by nesting in the metallic bands, and resulting in energy gaps and periodic lattice distortions at low temperature.However, several pieces of evidence do not suppor...

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This study subjected laboratory‐scale test cells to testing methods for dynamic charge acceptance (DCA) that have recently been developed and published for 12 V automotive batteries, particularly enhanced flooded batteries (EFB). The main focus of the study lies on the scaling and geometry effects of different test cell compositions as well as the comparability between the DCA testing methods. The test cells for this study are extracted from industrially manufactured automotive batteries; each cell had either a full set of plates, or a reduced, negative‐limited set of plates. DCA measurements are performed according to SBA S0101:2014, EN 50 342‐6:2015, and a run‐in DCA drive cycle test. The results indicate that DCA generally increases as plate count falls. The correlation between short DCA tests and run‐in DCA under realistic operating conditions is as weak for individual cells as it is known to be for entire batteries. However, DCA stabilized somewhat more quickly in test cells than in batteries.

Including a certain amount of carbon in the negative active material is currently the state‐of‐the‐art method to improve the dynamic charge acceptance (DCA) of lead–acid batteries. The DCA is a key parameter of batteries used in microhybrid cars where brake energy recuperation is implemented. To find the optimal carbon additive, it is essential to test the carbon both in short‐term and long‐term tests. This work investigates the long‐term and short‐term DCA of 2 V, 2.5 Ah lead–acid cells and correlates the results with the external surface area of the carbon. Five different carbons with tailored particle size (27–633 nm) and external surface area (7.1–159.3 m2 g−1) are employed as additives in the negative electrodes. The charge acceptance of cells according to the charge acceptance test 2 (SBA), the DCA (EN) test, and the run‐in DCA test (Ford) is increased via an increase in the carbon external surface area. A correlation between the short‐term tests and the first week of the run‐in DCA test is established for the carbon impact. After several weeks of run‐in DCA test, the carbon effect is diminished and only a differentiation between high and low DCA cells is possible.