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The magnetic properties of a series of trimetallic (Co,Ni)Fe Prussian blue analogues (PBAs) were investigated by SQUID magnetometry and X-ray magnetic circular dichroism (XMCD) at the three transition metal (TM) K-edges. In turn, the PBA trimetallic series was used as a tool in order to better understand the information contained in TM K-edge XMCD and particularly the chemical nature of the probed species (extended sub-lattice or localized entities). The results show that the magnetic behavior of the compounds is dictated by competing exchange interactions between the Co–Fe and Ni–Fe pairs, without spin frustration. They also show that XMCD at the TM K-edge is a local atomic probe of the element at the N side of the cyanide bridge and a local probe of the absorbing atom and its first magnetic neighbors on the C side of the bridge. At last, XMCD at the TM K-edge turns out to be highly sensitive to very small structural distortions. [ABSTRACT FROM AUTHOR]

Many fundamental processes of structural changes at surfaces occur on a pico- or femtosecond timescale. In order to study such ultrafast processes, we have combined modern surface science techniques with fs-laser pulses in a pump–probe scheme. Grazing incidence of the electrons ensures surface sensitivity in ultrafast reflection high-energy electron diffraction (URHEED). Utilizing the Debye–Waller effect, we studied the nanoscale heat transport from an ultrathin film through a hetero-interface or the damping of vibrational excitations in monolayer adsorbate systems on the lower ps-timescale. By means of spot profile analysis, the different cooling rates of epitaxial Ge nanostructures of different size and strain state were determined. The excitation and relaxation dynamics of a driven phase transition far away from thermal equilibrium is demonstrated using the In-induced (8 × 2) reconstruction on Si(111). This Peierls-distorted surface charge density wave system exhibits a discontinuous phase transition of first order at 130 K from a (8 × 2) insulating ground state to (4 × 1) metallic excited state. Upon excitation by a fs-laser pulse, this structural phase transition is non-thermally driven in only 700 fs into the excited state. A small barrier of 40 meV hinders the immediate recovery of the ground state, and the system is found in a metastable supercooled state for up to few nanoseconds. [ABSTRACT FROM AUTHOR]

Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic-scale electric field and charge density distribution of WSe 2 bi- and trilayers are revealed using an emerging microscopy technique, differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Transition metal complexes, particularly copper hydrides, play an important role in various catalytic processes and molecular inorganic chemistry. This study employs synchrotron hard X-ray spectroscopy to gain insights into the geometric and electronic properties of copper hydrides as potential catalysts for CO 2 hydrogenation. The potential of high energy resolution X-ray absorption near-edge structure (HERFD-XANES) and valence-to-core X-ray emission (VtC-XES) is demonstrated with measurement on Stryker's reagent (Cu 6 H 6 ) and [Cu 3 (μ 3 -H)(dpmppe) 2 ](PF 6 ) 2 (Cu 3 H), alongside a non-hydride copper compound ICu(dtbppOH) (Cuy-I). The XANES analysis reveals that coordination geometries strongly influence the spectra, providing only indirect details about hydride coordination. The VtC-XES analysis exhibits a distinct signal around 8975 eV, offering a diagnostic tool to identify hydride ligands. Theoretical calculations support and extend these findings by comparing hydride-containing complexes with their hydride-free counterparts., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The nonlinear (NL) optical response of bulk lithium niobate (LiNbO3) was investigated at 532 nm using the second harmonic of a Nd:YAG laser delivering pulses of 12 ps. The experiments were performed using the D4r method combined with the conventional Z-scan technique. Two- and three-photon absorption coefficients equal to 0:27 cm=GW and 2:5 x 10-26 m³/W², respectively, were determined. The NL absorption processes were due to transitions from the valence to the conduction band and to free-carrier absorption. The third- and fifth-order NL refractive indices were n2 = (2.5±0.6) x 10-19 m²/W and n4 < 5:5 x 10-36 m4=W². The present results give the support for previous experiments that indicate possible fifth-order processes in bulk samples and channel waveguides fabricated with LiNbO3. [ABSTRACT FROM AUTHOR]

Some specific features of synchrotron X-ray absorption and scattering in matter are considered as a basis for the methods of studying the electronic, magnetic, phonon, and structural properties of condensed media. Their theoretical description is given within the quasirelativistic approximation of the Dirac equation. This makes it possible not only to describe the experimentally observed phenomena, but also to predict new spin-position effects in resonant scattering. [ABSTRACT FROM AUTHOR]

The silicon carbide (SiC) 3C polytype microparticles with p‐type conductivity are investigated by X‐band electron paramagnetic resonance (EPR) technique in a wide temperature interval. Morphological and Raman studies show that the mean particle diameter is ≈8 μm, and the SiC polytype is purely 3C. At T = 10 K, the EPR spectrum of the shallow boron acceptor substituting cubic site (BK), with C3V symmetry and anisotropic g‐ and A‐tensors resulting from static Jahn–Teller effect, is observed. At T > 30 K, a continuous transition from static to dynamic Jahn–Teller effect for BK is detected. The temperature‐dependent BK principal g‐values are explained by the transitions between the ground and excited vibronic states of BK. At T = 130–150 K, the BK center is characterized by Td symmetry and isotropic g‐ and A‐tensors. At T = 60–190 K, an additional single EPR Lorentzian line with short spin relaxation times and isotropic g‐value close to BK average g‐value is observed. It was explained by averaging the anisotropic spectrum caused by rapid transitions between the boron ground and excited vibronic states split by Jahn–Teller potential. In addition, the EPR signal from carbon vacancy with characteristic superhyperfine structure is observed at T = 10–298 K. [ABSTRACT FROM AUTHOR]

A surface‐enhanced Raman scattering‐chiral anisotropy (SERS‐ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS‐ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs. [ABSTRACT FROM AUTHOR]

Based on first‐principles calculations, the electronic structures of the van der Waals heterostructures formed by bilayer‐Bi(111) and graphene are systematically studied. Although the Bi–graphene spacing is larger than 3 Å, the topological bandgap (TBG) of bilayer‐Bi(111) can be tuned by the weak Bi–graphene interaction and the stacking pattern between Bi and graphene. In the zigzag–zigzag stacking pattern, the TBG can be enlarged by reducing the Bi–graphene spacing or the buckling of bilayer‐Bi(111). Interestingly, in the zigzag–armchair stacking pattern, there is a new hybridization gap in a bilayer‐Bi(111) near Fermi level. Meanwhile, the TBG of bilayer‐Bi(111) can also be modified in the heterostructures. However, a large bandgap (more than 100 meV) can be realized in graphene by tuning the Bi–graphene spacing. The calculations suggest the importance of stacking pattern and hybridization on the electronic structures. [ABSTRACT FROM AUTHOR]

At first we discuss one-electron X-ray magnetic circular dichroism (XMCD) theory on the basis of Gesztesy expansion of Dirac Green's function in terms of nonrelativistic ones with potential. Applying the approximation used to derive Pauli equation from Dirac equation, we obtain the electron–photon interaction operator which includes spin-position operator in addition to the electric and magnetic multipole operators. The spin-position operator inherent to the relativistic effects plays quite important roles in K-edge XMCD analyses as pointed out by Bouldi and Brouder. A many-body XMCD theory is developed on the basis of relativistic quantum electrodynamics (QED) with aid of the relativistic Keldysh Green's functions, which allows us to treat XMCD spectra quite naturally: Some important many-body effects, like radiation field screening, loss effects and optical potentials, are studied from first principles. For example, the radiation field screening is incorporated beyond linear response theory, which is responsible for the deviation from the statistical weight of the L2/L3 branching ratio. Retarded and advanced Green's functions can be expanded in terms of nonrelativistic correlated Green's functions. Some XMCD sum rules are studied using many-body density matrix, which includes solid state effects. Discussion is separately given for L2,3, and K edge excitations. [ABSTRACT FROM AUTHOR]

Established and recent hard X-ray spectroscopic methods in the form of conventional X-ray absorption near edge structure spectroscopy (XANES) and extended X-ray absorption fine structure spectroscopy (EXAFS), and the photon-in/photon-out techniques high energy resolution fluorescence detection XANES and valence-to-core X-ray emission spectroscopy (VtC-XES) provide unique opportunities to study mechanisms in metal–organic reactions. The combination of these techniques allows the determination of the local geometric and electronic structures in the form of the numbers of nearest neighbours, their types and distances around an X-ray absorbing atom and the highest occupied and lowest unoccupied molecular levels. Different sample cells for this purpose, which allow high pressure, electrochemical or multi-spectroscopic measurements under inert conditions, are presented and discussed. The potential of HERFD-XANES and VtC-XES to eliminate limitations of conventional EXAFS spectroscopy is established with case studies on the Hieber anion [Fe(CO)3(NO)]− and the iron hydride complex [Fe(CO)H(NO)(PPh3)2]. With VtC-XES the formation of an allyl complex by reaction of [Fe(CO)3(NO)]− in a catalytic nucleophilic substitution reaction can be followed. Combination of HERFD-XANES and VtC-XES allows the identification and investigation of hydride species, as well as their fate in chemical reactions. On the other hand, in order to investigate the active species formation in iron-catalysed cross coupling reactions, conventional XANES and EXAFS are the method of choice for the moment. For all examples, the advantages and limitations of the hard X-ray toolbox are commented on and the value of the individual methods are compared. [ABSTRACT FROM AUTHOR]

Strong optical irradiation of indium atomic wires on a Si(111) surface causes the nonthermal structural transition from the (8 × 2) reconstructed ground state to an excited (4 × 1) state. The immediate recovery of the system to the ground state is hindered by an energy barrier for the collective motion of the indium atoms along the reaction coordinate from the (4 × 1) to the (8 × 2) state. This metastable, supercooled state can only recover through nucleation of the ground state at defects like adsorbates or step edges. Subsequently, a recovery front propagates with constant velocity across the surface and the (8 × 2) ground state is reinstated. In a combined femtosecond electron diffraction and photoelectron emission microscopy study, we determined—based on the step morphology—a velocity of this recovery front of ∼100 m/s. [ABSTRACT FROM AUTHOR]

Due to their large importance in synthetic chemistry, catalytic C−C coupling reactions of phenols are currently intensively studied. Herein, new copper catalysts for the C−C coupling reaction of phenols using dioxygen as a green oxidizing reagent are reported. By using redox‐active guanidine ligands, the activity as well as chemoselectivity in the cross‐coupling reaction of non‐complementary phenols (between an electron‐rich phenol and a less nucleophilic second phenol) is significantly improved. Based on the collected data for several test reactions, a reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

We present a newly designed 30 kV pulsed electron gun for ultrafast electron diffraction suited for pump-probe setups driven by femtosecond laser pulses. The electron gun can be operated both in transmission and reflection geometry. A robust design with a back illuminated Au photocathode, extraction fields of 7.5 kV/mm, and a magnetic focus lens ensures reliable daily use. Magnetic deflectors allow for beam alignment and characterization. Focusing of the UV pulse on the photocathode results in a small source size of photoemitted electrons and thus a high transverse coherence length of more than 50 nm in diffraction. A low difference of ΔE = 0.1 eV between the work function of the 10 nm Au photocathode and photon energy of the frequency tripled UV laser pulses results in an instrumental temporal resolution of 330 fs full width at half maximum. This resolution is discussed with respect to the number of electrons per pulse. [ABSTRACT FROM AUTHOR]

The impact of condensed‐phase and finite‐temperature effects on the theoretical X‐ray absorption spectra of transition metal complexes is assessed. The former are included in terms of the all‐electron Gaussian and augmented plane‐wave approach, whereas the latter are taken into account by extensive ensemble averaging along second‐generation Car–Parrinello ab initio molecular dynamics trajectories. We find that employing the periodic boundary conditions and including finite‐temperature effects systematically improves the agreement between our simulated X‐ray absorption spectra and experimental measurements. © 2018 Wiley Periodicals, Inc. Theoretical condensed‐phase X‐ray absorption spectra, as computed by the combined second‐generation Car–Parrinello molecular dynamics and all‐electron Gaussian and augmented plane‐wave approach, suggest that the usage of periodic boundary conditions and inclusion of finite‐temperature effects entails a systematic improvement within the X‐ray absorption fine structure range. [ABSTRACT FROM AUTHOR]

Intramolecular electron transfer (IET) processes between the metal and a redox‐active ligand in a transition‐metal complex are currently intensively studied, as they represent key steps of some redox‐catalytic reactions in synthetic chemistry and of some enzymatic redox reactions in biological systems. Using a combination of experimental results and quantum chemical calculations, we herein examine in detail the role of the solvent polarity and seemingly small modifications at the redox‐active ligand on IET processes in mononuclear copper complexes with redox‐active bisguanidine ligands. A direct and simple correlation between the coordination mode and the electronic structure in these complexes is established, assisting in the fine‐tuning of the ligand properties for optimal promotion of IET. [ABSTRACT FROM AUTHOR]

2,3-Bis- and 2,3,7,8-tetrakisguanidino-substituted phenazines are intensely-coloured dyes that offer two different sites for metal coordination or benzylation, namely the imino nitrogen atoms of the guanidino groups and the phenazine nitrogen atoms. In this work, sequential coordination at both sites is studied, and the effects on the electronic structure and optical properties are analyzed. The step-wise coordination is used to synthesize tetranuclear mixed-valence (CuI)2(CuII)2 and heterobimetallic Cu2Ni2 complexes. Coordination at the guanidino groups switches on a ligand–metal charge-transfer character of electronic transitions in the visible region, leading to a massive intensity gain in the case of copper coordination. The second coordination step with CuI takes place at the phenazine nitrogen atoms and further decreases the ligand frontier orbitals. In the case of two tricoordinated CuI atoms in the product complex, the charge-transfer character of the electronic excitation vanishes, while their energies are very similar. On the other hand, for CuI atoms with a coordination number of only 2, the stronger Cu–N bond leads to a red-shift of the electronic transitions. [ABSTRACT FROM AUTHOR]

The possibility of directed stimulation of intramolecular electron transfer between a metal and a redox-active ligand in a molecular coordination compound is the key to its application in molecular catalysis and other research themes. Although the stimulation by a substitution reaction of the co-ligands is often postulated as key step in catalytic cycles using redox-active ligands as electron reservoirs, there are only a few explicit examples for such reactions. Herein we report the synthesis of the first dicationic and dinuclear CuI complexes featuring the oxidized form of a redox-active tetrakisguanidine ligand (1,2,4,5-tetrakis(tetramethylguanidino)benzene 1) as a bridging ligand and two neutral co-ligands L (acetonitrile or pyridine), [1{Cu(Cl)L}2]2+. An intramolecular electron transfer between the copper atom and the tetrakisguanidine ligand 1, leading to a dinuclear CuII complex with the reduced form of the tetrakisguanidine ligand 1, is triggered by substitution of the neutral co-ligands L. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC), is an artificial semiconductor used for high‐power transistors and blue LEDs, for its extraordinary properties. SiC will be attractive for more applications, but large‐scale or large‐surface area fabrication, with control over defects and surface is challenging. Sol‐gel based techniques are an affordable alternative toward such requirements. This report describes two types of microcrystalline SiC derived after carbothermal reduction from sol‐gel‐based precursors, one with nitrogen added, the other aluminum. Characterization of their bulk, structure, and surface shows that incorporation of dopants affects the formation of polytypes and surface chemistry. Nitrogen leads exclusively to cubic SiC, exhibiting a native oxide surface. Presence of aluminum instead promotes growth of hexagonal polytypes and induces self‐passivation of the crystallites’ surface during growth. This is established by hydrogenation of silicon bonds and formation of a protecting aluminum carbonate species. XPS provides support for the suggested mechanism. This passivation is achieved in only one step, solely by aluminum in the precursor. Hence, it is shown that growth, doping and passivation of SiC can be performed as “one‐pot synthesis”. Material without insulating oxide and a limited number of defects is highly valuable for applications involving surface‐sensitive charge‐transfer reactions, therefore the potential of this method is significant. [ABSTRACT FROM AUTHOR]

The sequential derivation of an expression that describes an X-ray natural circular dichroism (XNCD) signal in the most general case is performed. The obtained expression is used as a basis to consider XNCD signals and their structural origins in copper metaborate CuB2O4 crystals at an incident radiation energy near the K absorption edge of copper and lanthanum-gallium silicate La3Ga5SiO14 crystals at an incident radiation energy near the K absorption edge of gallium. It has been demonstrated that the measurements of circularly polarized X-ray absorption spectra in combination with corresponding first-principle calculations provide an efficient method for studying the contributions of crystallographically non-equivalent atoms to the X-ray optical activity of crystals. [ABSTRACT FROM AUTHOR]

The photoinduced structural dynamics of the atomic wire system on the Si(111)-In surface has been studied by ultrafast electron diffraction in reflection geometry. Upon intense fs-laser excitation, this system can be driven in around 1 ps from the insulating ( 8 × 2 ) reconstructed low temperature phase to a metastable metallic ( 4 × 1 ) reconstructed high temperature phase. Subsequent to the structural transition, the surface heats up on a 6 times slower timescale as determined from a transient Debye-Waller analysis of the diffraction spots. From a comparison with the structural response of the high temperature ( 4 × 1 ) phase, we conclude that electron-phonon coupling is responsible for the slow energy transfer from the excited electron system to the lattice. The significant difference in timescales is evidence that the photoinduced structural transition is non-thermally driven. [ABSTRACT FROM AUTHOR]

Synthetic diiron compounds of the general formula Fe2(μ-S2R)(CO)n(L)6−n (R = alkyl or aromatic groups; L = CN− or phosphines) are versatile models for the active-site cofactor of hydrogen turnover in [FeFe]-hydrogenases. A series of 18 diiron compounds, containing mostly a dithiolate bridge and terminal ligands of increasing complexity, was characterized by X-ray absorption and emission spectroscopy in combination with density functional theory. Fe K-edge absorption and Kβ main-line emission spectra revealed the varying geometry and the low-spin state of the Fe(i) centers. Good agreement between experimental and calculated core-to-valence-excitation absorption and radiative valence-to-core-decay emission spectra revealed correlations between spectroscopic and structural features and provided access to the electronic configuration. Four main effects on the diiron core were identified, which were preferentially related to variation either of the dithiolate or of the terminal ligands. Alteration of the dithiolate bridge affected mainly the Fe–Fe bond strength, while more potent donor substitution and ligand field asymmetrization changed the metal charge and valence level localization. In contrast, cyanide ligation altered all relevant properties and, in particular, the frontier molecular orbital energies of the diiron core. Mutual benchmarking of experimental and theoretical parameters provides guidelines to verify the electronic properties of related diiron compounds. [ABSTRACT FROM AUTHOR]

A numerically efficient yet highly accurate implementation of the crystal orbital Hamilton population (COHP) scheme for plane-wave calculations is presented. It is based on the projector-augmented wave (PAW) formalism in combination with norm-conserving pseudopotentials and allows to extract chemical interactions between atoms from band-structure calculations even for large and complex systems. The potential of the present COHP implementation is demonstrated by an in-depth analysis of the intensively investigated metal-insulator transition in atomic-scale indium wires self-assembled on the Si(111) surface. Thereby bond formation between In atoms of adjacent zigzag chains is found to be instrumental for the phase change. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Fast and efficient electron transfer in blue copper proteins is realized by a structural harmonization between the CuI and CuII complex pair ('entatic state' model). Herein, we present now a CuI/CuII complex pair with redox-active guanidine ligands showing almost perfect match between both redox states. By modifying the ligand electron donor strength, the redox chemistry of the copper complex can be controlled to be either metal-centered or to cross the borderline to ligand-centered. This work is the first systematic study of complexes with redox-active ligands within the concept of the entatic state. [ABSTRACT FROM AUTHOR]

Magnetically doped topological insulators (TIs) exhibit several exotic phenomena including the magnetoelectric effect and quantum anomalous Hall effect. However, from an experimental perspective, incorporation of spin moment into 3D TIs is still challenging. Thus, instead of 3D TIs, the 2D form of TIs may open up new opportunities to induce magnetism. Based on first principles calculations, we demonstrate a novel strategy to realize robust magnetism and exotic electronic properties in a 2D TI [bilayer Bi(111) film: abbreviated as Bi(111)]. We examine the magnetic and electronic properties of Bi(111) with defects such as bismuth monovacancies (MVs) and divacancies (DVs), and these defects decorated with 3d transition metals (TMs). It has been observed that the MV in Bi(111) can induce novel half metallicity with a net magnetic moment of 1 μB. The origin of half metallicity and magnetism in MV/Bi(111) is further explained by the passivation of the σ-dangling bonds near the defect site. Furthermore, in spite of the nonmagnetic nature of DVs, the TMs (V, Cr, Mn, and Fe) trapped at the 5/8/5 defect structure of DVs can not only yield a much higher spin moment than those trapped at the MVs but also display intriguing electronic properties such as metallic, semiconducting and spin gapless semiconducting properties. The predicted magnetic and electronic properties of TM/DV/Bi(111) systems are explained through density of states, spin density distribution and Bader charge analysis. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations with localized as well as plane-wave basis functions are performed for the recently reported dicopper thiolate species Cu2(NGuaS)2Cl2 [NGuaS = 2-(1,1,3,3-tetramethylguanidino) benzenethiolate, C11H16N3S] and its bromo derivative [Neuba et al., Angew. Chem. Int. Ed. 2012, 51, 1714.]. For both hybrid and semilocal functionals, the neutral complexes are found to have broken symmetry (BS) character, with electron paramagnetic resonance silent, antiferromagnetically coupled [Cu2+...Cu2+] site in which the coupling is driven by super exchange interaction within the Cu2S2 diamond core. The accurate theoretical description of the geometric structure, however, provides a major challenge for DFT: ( i) the multideterminant character of the ground state wave function has to be covered by the BS approach. It requires ( ii) metageneralized gradient approximations, that is hybrid functionals with an explicit dependence on the kinetic energy of the individual orbitals: In combination with a dispersion correction, the metafunctional TPSSh results in a CuCu distance close to the experimentally observed value of 2.7 Å. For the negative charge state of the complex, a mixed-valent [Cu1.5+...Cu1.5+] electronic structure with a smaller CuCu distance of 2.6 Å is predicted, similar to the value of the Cu A site of cytochrome c oxidase. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Raman spectroscopy has evolved to a sensitive tool for analyzing vibration modes of ordered (sub)monolayers of metal adatoms on semiconductor surfaces, which are typical systems for electron correlation effects. We report on the in situ UHV Raman analysis of self‐organized Au submonolayers on nominal Si(111) surfaces, as well as on vicinal Si(553), Si(775), and Si(557). For the two‐dimensional Au‐(3×3) and the one‐dimensional Au‐(5 × 2) reconstruction several specific Raman peaks in the spectral range below 200 cm−1 are assigned to Au‐dominated vibration modes, while Si‐step‐edge vibration modes around 400 cm−1 are fingerprints of the substrate orientation. Surface atomic structures and associated Raman spectra of Au‐terminated Si surfaces: The two‐dimensional Au‐(3×3) and the one‐dimensional Au‐(5 × 2) reconstruction are displayed. The Raman spectra show the surface vibrational contribution, that is, after subtraction of the Si bulk scattering. The surface vibrations are specific for the structure and chemical bonding of the uppermost few atomic planes, and thus, a very sensitive measure of surface structure is achieved. This link can be used to clarify details of the respective surface atomic structures. [ABSTRACT FROM AUTHOR]