Unveiling the nature of atomic defects in graphene on a metal surface

• Karl Rothe,
• Nicolas Néel and
• Jörg Kröger

Beilstein J. Nanotechnol. 2024, 15, 416–425, doi:10.3762/bjnano.15.37

• . Constant-height scanning tunneling spectroscopy (STS) of dI/dV was performed by sinusoidally modulating (5 mVrms, 725 Hz) the dc bias voltage and measuring the first harmonic of the ac current response of the tunneling junction with a lock-in amplifier. For AFM data acquisition, resonance frequency changes

• from STS experiments [49][50][51], it is lower than the energy observed in photoemission experiments [52]. A possible rationale is the locally lifted graphene in the presence of the tip [53], which in turn decreases the charge transfer from graphene to the metal and reduces the p-doping [52] and

• concomitantly causes a lowering of the Dirac point energy. Type-1 defects exhibit the same behavior in spatially resolved STS measurements, independent of the moiré valley they reside at. In contrast, dI/dV data acquired above 2 are essentially identical to spectroscopic data of pristine graphene (Figure 1e

Self-assembly of C₆₀ on a ZnTPP/Fe(001)–p(1 × 1)O substrate: observation of a quasi-freestanding C₆₀ monolayer

• Guglielmo Albani,
• Michele Capra,
• Alessandro Lodesani,
• Alberto Calloni,
• Gianlorenzo Bussetti,
• Marco Finazzi,
• Franco Ciccacci,
• Alberto Brambilla,
• Lamberto Duò and
• Andrea Picone

Beilstein J. Nanotechnol. 2022, 13, 857–864, doi:10.3762/bjnano.13.76

• W tips. Scanning tunneling spectroscopy (STS) data, that is, dI/dV curves for the investigation of the sample density of states (DOS), have been collected at room temperature, using a lock-in amplifier with a modulation amplitude of 60 mV. All STM and STS measurements have been carried out while

• to C 2p electrons [56]. Therefore, it is present with only slight modifications both in ZnTPP/Fe(001)–p(1 × 1)O and C60/ZnTPP/Fe(001)–p(1 × 1)O samples. In order to determine the HOMO–LUMO gap of the C60 film, STS measurements have been acquired for both negative and positive bias to investigate the

• filled and empty electronic states, respectively. Figure 4 shows STS spectra acquired on the ZnTPP/Fe(001)–p(1 × 1)O surface (red) and on the C60/ZnTPP/Fe(001)–p(1 × 1)O system (black). The STS measurements acquired on ZnTPP/Fe(001)–p(1 × 1)O are in excellent agreement with those published in [43]. The

Topographic signatures and manipulations of Fe atoms, CO molecules and NaCl islands on superconducting Pb(111)

• Carl Drechsel,
• Philipp D’Astolfo,
• Jung-Ching Liu,
• Thilo Glatzel,
• Rémy Pawlak and
• Ernst Meyer

Beilstein J. Nanotechnol. 2022, 13, 1–9, doi:10.3762/bjnano.13.1

• scanning tunneling spectroscopy (STS) is a zero-bias conductance peak occurring at boundaries and defects. Unfortunately, other structural peculiarities can also mimic such zero-bias anomalies, which eventually leads to severe misinterpretations. Therefore, the latest advances in scanning tunneling

Molecular assemblies on surfaces: towards physical and electronic decoupling of organic molecules

• Sabine Maier and
• Meike Stöhr

Beilstein J. Nanotechnol. 2021, 12, 950–956, doi:10.3762/bjnano.12.71

• these decoupling layers to the organic molecules and vice versa. This has the great advantage that these systems can still be examined by scanning tunneling microscopy (STM) and spectroscopy (STS), which gives insight into structural and electronic properties of individual molecules. For applications

• . The significantly reduced resonance width allowed for resolving vibronic states in both frontier orbitals on graphene/Pt(111) by STS. The semiconducting 2D material MoS2 may act as a decoupling layer for molecules from the underlying metal substrate if the molecular resonances lie within the MoS2

• situated at the conduction band onset of MoS2. Despite this, the vibronic states of the transiently negatively charged TCNQ could be resolved by STS. hBN is an insulator and has therefore been widely used to decouple organic molecules from metal substrates. Three articles within this Thematic Issue

Extended iron phthalocyanine islands self-assembled on a Ge(001):H surface

• Rafal Zuzak,
• Marek Szymonski and
• Szymon Godlewski

Beilstein J. Nanotechnol. 2021, 12, 232–241, doi:10.3762/bjnano.12.19

• scanning tunneling spectroscopy (STS) measurements indicate that the FePc molecules stay intact upon adsorption on the Ge(001):H surface. The gap measured with STS matches well independently recorded data for weekly coupled FePc molecules. Also, it is in good agreement with optical measurements, indicating

• on TiO2 [67]. For clarity, the simplified schematic drawings of the α and β phases and our models are shown in Figure 4. In order to acquire information on the electronic properties of the FePc molecules within the islands on the Ge(001):H we have performed STS measurements. Figure 5 shows a single

• STS data recorded on the islands indicated a transport gap of approximately 2.70 eV, which is in good agreement with previously reported values for isolated molecules. Since the Ge(001):H surface contains atomic-scale defects, a fraction of FePc molecules was found flat-lying and immobilized at these

The influence of an interfacial hBN layer on the fluorescence of an organic molecule

• Christine Brülke,
• Oliver Bauer and
• Moritz M. Sokolowski

Beilstein J. Nanotechnol. 2020, 11, 1663–1684, doi:10.3762/bjnano.11.149

• bandgap of hBN, as indicated in Figure 1b. This is in agreement with the findings by Martínez-Galera et al. for PTCDA/hBN/Rh(110) [34]. From scanning tunneling spectroscopy (STS) experiments, the authors concluded that the coupling is only weak. They deduced further that the CT (in the ground state

• ]. This again points to a difference in the bonding character on the two surfaces. Several studies have probed the influence of the adsorption on metal-supported hBN layers on the electronic structure of large organic molecules, namely their frontier orbitals, by PES [36] or STS [37][38]. However, to the

Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111)

• Domenik M. Zimmermann,
• Knud Seufert,
• Luka Ðorđević,
• Tobias Hoh,
• Sushobhan Joshi,
• Tomas Marangoni,
• Davide Bonifazi and
• Willi Auwärter

Beilstein J. Nanotechnol. 2020, 11, 1470–1483, doi:10.3762/bjnano.11.130

• . Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of the pyrene derivatives adsorbed on a Cu(111)-supported hexagonal boron nitride (hBN) decoupling layer provided access to spatially and energetically resolved molecular electronic states. We demonstrate that the pyrene electronic gap

• properties in organic layers relied on bulk insulator supports [14][15][16]. As a promising alternative to bulk insulators, ultrathin dielectric films can act as decoupling layers but maintain the possibility to perform STM and STS measurements [17]. Atomically-thin hBN sheets attracted considerable interest

• allows the determination of the electronic properties of the pyrene adsorbates by STM and STS", and the comparison with the gaps estimated by theoretical simulations in vacuum and by UV-vis spectroscopies in solution. Remarkably, the electronic states of the pyrene adsorbates near the Fermi level, probed

Scanning tunneling microscopy and spectroscopy of rubrene on clean and graphene-covered metal surfaces

• Karl Rothe,
• Alexander Mehler,
• Nicolas Néel and
• Jörg Kröger

Beilstein J. Nanotechnol. 2020, 11, 1157–1167, doi:10.3762/bjnano.11.100

• ] and hexagonal boron nitride (h-BN) [3] have been studied in detail. In contrast, vibrational spectroscopy at the single-molecule level is scarce. Scanning tunneling spectroscopy (STS) of vibronic levels of 1,3,5-tris(2,2-dicyanovinyl)benzene on graphene-covered h-BN on SiO2 [4], of cobalt

• expected to be well decoupled from the metal substrate. After adsorption of C42H28 on Pt(111) scanning tunneling microscopy (STM) images reveal the occurrence of separate molecular clusters and very broad molecular resonances in STS data, which is attributed to an elevated C42H28–Pt interaction. On Au(111

• . Before corroborating the suggestion of elevated molecule–substrate coupling by STS data the occurrence of chiral molecular species shall be discussed. The close-up STM image in Figure 2c shows adsorbed C42H28 molecules that appear with three rather than two lobes. Moreover, numbering the brightest to the

Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower

• Rouzhaji Tuerhong,
• Mauro Boero and
• Jean-Pierre Bucher

Beilstein J. Nanotechnol. 2019, 10, 1243–1250, doi:10.3762/bjnano.10.124

• of the molecule become accessible. In this context, inelastic electron tunneling spectroscopy (IETS) based on scanning tunneling spectroscopy (STS) has proven to be a powerful technique to investigate and identify molecular objects and their interactions with the environment. The technique allows one

• surfaces [13][14][15][16][17][18][19][20][21]. Low-temperature STM/STS is an ideal tool to study the Kondo effect, which manifests itself by a sharp zero-bias resonance in the conductance spectrum of a localized moment on a conducting substrate, due to the coherent spin-flip scattering between the

• in the gap of the STM is investigated by probing the differential conductance through the junction. The STS spectrum of a MnPc molecule flat-lying on Au(111) is taken with a bare metallic tip and used as a reference spectrum to be compared with the STS result obtained with a MnPc-terminated tip

Intercalation of Si between MoS₂ layers

• Rik van Bremen,
• Qirong Yao,
• Soumya Banerjee,
• Deniz Cakir,
• Nuri Oncel and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2017, 8, 1952–1960, doi:10.3762/bjnano.8.196

• into this picture. In order to verify our interpretation we have performed additional scanning tunneling spectroscopy (STS) measurements. I(V) scanning tunneling spectra were recorded at the hills and valleys as indicated by the arrows in Figure 1d. Average spectroscopy curves of a hill and of a valley

• reveals that Si does not grow on top of the MoS2 substrate, but rather intercalates in between the MoS2 layers. It is known that layered materials such as MoS2 have a tendency to host intercalants. In this work we provide additional evidence for silicon intercalation by using STS and XPS. Since silicon

• valley (dark). (e) High-resolution STM image taken after the deposition of 0.2 monolayers of Si. (f) Line scans taken along the lines indicated in panel (e). The sample bias is 1.2V and the tunnelling current is 0.5 nA. STS recorded at the hills (black curve) and at the valleys (red curve). Set points

Structural model of silicene-like nanoribbons on a Pb-reconstructed Si(111) surface

• Agnieszka Stępniak-Dybala and
• Mariusz Krawiec

Beilstein J. Nanotechnol. 2017, 8, 1836–1843, doi:10.3762/bjnano.8.185

• substrates. Experimental and Computational Details All the measurements have been done under UHV conditions with a 4He-cooled scanning tunneling microscope (Omicron) working at 4.5 K. For STM/STS measurements electrochemically etched tungsten was used. The Pb/Si(111) sample was prepared in situ by

• diffuse on Si substrates [53][54], so they can easily make room for growing Si NRs. Furthermore, different STS characteristics acquired on top of the NRs and in between them also point against Pb-composed nanoribbons. The experimental findings suggest that the observed nanostructures are wide nanoribbons

Three-in-one approach towards efficient organic dye-sensitized solar cells: aggregation suppression, panchromatic absorption and resonance energy transfer

• Jayita Patwari,
• Samim Sardar,
• Bo Liu,
• Peter Lemmens and
• Samir Kumar Pal

Beilstein J. Nanotechnol. 2017, 8, 1705–1713, doi:10.3762/bjnano.8.171

• collection of the steady-state absorption spectra and the emission spectra, respectively. The solid-state absorption spectra were recorded in reflecting mode using a STS-VIS-L10-400-SMA spectrograph with wavelength resolution of 0.47 nm. For the transmission and collection of light, a lab-grade optical fiber

Adsorption and electronic properties of pentacene on thin dielectric decoupling layers

• Sebastian Koslowski,
• Daniel Rosenblatt,
• Alexander Kabakchiev,
• Klaus Kuhnke,
• Klaus Kern and
• Uta Schlickum

Beilstein J. Nanotechnol. 2017, 8, 1388–1395, doi:10.3762/bjnano.8.140

• gap of the molecules. In spite of the enhanced interaction, the molecular orbitals are evident in scanning tunnelling spectroscopy (STS) and their shapes can be resolved by spectroscopic mapping. Keywords: hexagonal boron nitride (h-BN); metal insulating organic interface; pentacene; potassium

• chloride (KCl); scanning tunnelling microscopy (STM); scanning tunnelling spectroscopy (STS); Introduction Miniaturization plays a paramount role in the development of modern technology. In order to further reduce the dimensions of the basic processing units, molecular electronics is a promising approach

• demonstrated by the observation of the unperturbed gas-phase-like frontier orbitals of pentacene on this substrate [3]. A weak interaction is nevertheless suggested by the observed shift of the orbital energies of the admolecule [4][7][8]. In scanning tunneling spectroscopy (STS) experiments on pentacene, two

Adsorption characteristics of Er₃N@C₈₀on W(110) and Au(111) studied via scanning tunneling microscopy and spectroscopy

• Sebastian Schimmel,
• Zhixiang Sun,
• Danny Baumann,
• Denis Krylov,
• Nataliya Samoylova,
• Alexey Popov,
• Bernd Büchner and
• Christian Hess

Beilstein J. Nanotechnol. 2017, 8, 1127–1134, doi:10.3762/bjnano.8.114

• it. In order to examine the adsorption characteristics and the electronic structure of Er3N@C80 in consideration of adsorbate–substrate interaction, we performed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) investigations on sub-monolayer covered W(110) and Au(111

• ) single crystal substrates. Beside their potential application as electrode materials, the choice of these established standard substrate for STM/STS investigations provides the advantages of comparability to results of earlier measurements and well-known fast cleaning treatments. Experimental Er3N@C80

• achieve the reproducible preparation of sub-monolayer Er3N@C80-coverage on substrates with the demanded cleanliness for systematically STM/STS investigations, the molecules were deposited via organic molecular beam epitaxy under ultra-high vacuum (UHV) conditions (p < 10−9 mbar) and subsequently analyzed

Novel roles for well-known players: from tobacco mosaic virus pests to enzymatically active assemblies

• Claudia Koch,
• Fabian J. Eber,
• Carlos Azucena,
• Alexander Förste,
• Stefan Walheim,
• Thomas Schimmel,
• Alexander M. Bittner,
• Holger Jeske,
• Hartmut Gliemann,
• Sabine Eiben,
• Fania C. Geiger and
• Christina Wege

Beilstein J. Nanotechnol. 2016, 7, 613–629, doi:10.3762/bjnano.7.54

• % surface coverage [88]. This work has recently been extended to a related potyvirus, potato virus A (PVA), which could be fashioned with similar surface density not only with 4CL2, but also with a two-enzyme mix of 4CL2 and stilbene synthase (STS) expressed in E. coli, or with a fusion protein of both

• discussed to promote health. Although, to date, the fusion protein has not exhibited detectable activity on PVA, and the resveratrol yield from the 4CL2/STS-PVA assemblies was relatively low, the functionality of the enzyme cascade was clearly demonstrated [155]. Further optimization and transfer to related

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• STM image revealed that the SAM structure of ferrocenyl adamantane 19 exhibits the same ordering and stability as that of 1-bromo-3,5,7-tris(sulfanylmethyl)adamantane 17 [108], where the SAMs are stable under low-bias-voltage scanning, i.e., with a sample bias voltage lower than 1 V. The STS

• measurements confirmed the characteristic molecular resonance states (HOMO−1, HOMO and LUMO) originating from the ferrocene group when spectrum was measured at ferrocenyl adamantane 19. The STS mapping succeeded in imaging the spatial distribution of the HOMO state of ferrocenyl adamantane 19, which is

Enhanced fullerene–Au(111) coupling in (2√3 × 2√3)R30° superstructures with intermolecular interactions

• Michael Paßens,
• Rainer Waser and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2015, 6, 1421–1431, doi:10.3762/bjnano.6.147

• islands [28][41][42]. The obtained orbital energies for the HOMO, the LUMO, and the LUMO+1 amount to −1.83 eV, 0.84 eV, and 2.08 eV, respectively. The LUMO exhibits a typical peak shape of 0.56 full width half maximum (FWHM). In addition we performed STS measurements on the u-R30° superstructures composed

• molecules. We hope, that these investigations will cause theoretical studies, which may give a detailed analysis of the interfacial and intermolecular interactions discussed here. Experimental Low-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS) experiments were carried out with a

Nano-contact microscopy of supracrystals

• Adam Sweetman,
• Nicolas Goubet,
• Ioannis Lekkas,
• Marie Paule Pileni and
• Philip Moriarty

Beilstein J. Nanotechnol. 2015, 6, 1229–1236, doi:10.3762/bjnano.6.126

• thick (i.e, ≈700 nanoparticle layers) are sufficiently conductive for STM and scanning tunnelling spectroscopy (STS) studies. However, not only are STM and STS measurements possible, but the quality of imaging is comparable to that attained on monolayer (or submonolayer) coverages of nanoparticles on

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

• Chris Hellenthal,
• Kai Sotthewes,
• Martin H. Siekman,
• E. Stefan Kooij and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2015, 6, 1116–1124, doi:10.3762/bjnano.6.113

• using closed-loop z(V) conductance scanning tunneling spectroscopy (STS) measurements for the determination of the effective tunneling barrier by comparing them to more conventional open-loop I(z) measurements. Through the development of a numerical model, the individual contributions to the effective

• charge; scanning tunneling spectroscopy (STS); tunneling barrier; work function; z(V); Introduction Although the scanning tunneling microscope (STM) has been used for the topographical imaging of conductive samples since the early 1980s [1], recent times have seen an increasing interest in the

• possibilities of (semi-)quantitative analysis offered by scanning tunneling spectroscopy (STS). STS measurements are typically performed in a X(Y) format, where variable Y is actively driven and the response of variable X is measured, with all other system variables being kept constant. Numerous types of STS

Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials

• Pascal R. Ewen,
• Jan Sanning,
• Tobias Koch,
• Nikos L. Doltsinis,
• Cristian A. Strassert and
• Daniel Wegner

Beilstein J. Nanotechnol. 2014, 5, 2248–2258, doi:10.3762/bjnano.5.234

• such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS

• spectroscopy (STS) makes it an ideal tool to study the electronic properties of adsorbed molecules with precise knowledge and control of the local environment around a single molecule. Although this method is limited to an energy range a few eV around the Fermi energy EF, this is usually sufficient to probe

• the relevant frontier orbitals [11][12][13][14][15]. Several studies have performed STM and STS on organometallic compounds, mainly on porphyrins and phthalocyanines [16][17][18][19][20][21][22]. Considering this general success, it is surprising that phosphorescent complexes have barely been

Sublattice asymmetry of impurity doping in graphene: A review

• James A. Lawlor and
• Mauro S. Ferreira

Beilstein J. Nanotechnol. 2014, 5, 1210–1217, doi:10.3762/bjnano.5.133

• sublattice asymmetry of N-graphene The main focus of the work by Zhao et al. was the observation and characterization of nitrogen dopants via scanning tunnel spectroscopy (STS), followed by a short investigation on the transport properties of the resulting graphene. Their experimental observation of same

Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

• Gernot Langewisch,
• Jens Falter,
• André Schirmeisen and
• Harald Fuchs

Beilstein J. Nanotechnol. 2014, 5, 98–104, doi:10.3762/bjnano.5.9

• dianhydride (PTCDA) adsorbed on the Ag(111) surface is a prototypical organic–anorganic interface that has been investigated by a large variety of different methods in the past [1]. Based on scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) experiments as well as theoretical

STM tip-assisted engineering of molecular nanostructures: PTCDA islands on Ge(001):H surfaces

• Amir A. Ahmad Zebari,
• Marek Kolmer and
• Jakub S. Prauzner-Bechcicki

Beilstein J. Nanotechnol. 2013, 4, 927–932, doi:10.3762/bjnano.4.104

• system [20]. Most of the islands have a height of 2.1 nm, what corresponds to 6 molecular layers. Insight into the electronic structure of the studied system is obtained by rt STS measurements (see Figure 1b). For a bare germanium surface a band gap of ≈0.2 eV is obtained, in fair agreement with

• window from −2.5 V to 1.7 V (corresponding to the semiconducting energy gap of PTCDA molecules) of the STS curves. This means that the electronic structure of PTCDA is unperturbed by the electronic properties of the underlying substrate. Figure 1c–f show a set of four consecutive scans of the same area

• subsequent scan (Figure 1d) one can observe a gradual growth of these features, eventually leading to their coalescence into one object (Figure 1e) that continues to gradually grow (Figure 1f). Typically, the morphology of PTCDA islands are stable during a STM/STS characterization. We assume that the

Physics, chemistry and biology of functional nanostructures

• Paul Ziemann and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2012, 3, 843–845, doi:10.3762/bjnano.3.94

• building blocks such as polythiophenes. These molecules are especially interesting for organic solar cells [11] and have been analyzed also by STS [12]. Of course, the contributions to this Thematic Series form just a snapshot of the current activities focused on functional nanostructures. We hope, however

An MCBJ case study: The influence of π-conjugation on the single-molecule conductance at a solid/liquid interface

• Wenjing Hong,
• Hennie Valkenier,
• Gábor Mészáros,
• David Zsolt Manrique,
• Artem Mishchenko,
• Alexander Putz,
• Pavel Moreno García,
• Colin J. Lambert,
• Jan C. Hummelen and
• Thomas Wandlowski

Beilstein J. Nanotechnol. 2011, 2, 699–713, doi:10.3762/bjnano.2.76

• single molecules or of a few molecules trapped between two leads were studied in various experimental platforms. These include scanning tunneling microscopy (STM) [27][28][29], current probe atomic force microscopy (CP-AFM) [30][31][32], scanning tunneling spectroscopy (STS) or STM-break junction (STM-BJ