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

• are indeed lacking the graphene atomic lattice structure in their interior. Spatially resolved spectroscopy of the differential conductance (dI/dV, I: tunneling current, V: bias voltage) and of the tuning fork resonance frequency change (Δf) further unravel marked differences between these two kinds

• . 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

• defects appear as depressions with no identifiable interior structure. Therefore, they may be interpreted as graphene vacancy sites, that is, as sites with missing C atoms. As shown by the spectra of dI/dV for the two defect types (Figure 1d,e) the electronic structure differs. Atop the center of 1

Observation of collective excitation of surface plasmon resonances in large Josephson junction arrays

• Roger Cattaneo,
• Mikhail A. Galin and
• Vladimir M. Krasnov

Beilstein J. Nanotechnol. 2022, 13, 1578–1588, doi:10.3762/bjnano.13.132

• not seen for smaller N. To quantify the step amplitude, ΔI, at small N we plot the differential conductance, dI/dV. Figure 5b shows the dI/dV(I) curves for the I–Vs from Figure 5a, normalized by the resonant voltage Vstep. This quantity does not depend on the number of active JJs. A current step in

• the I–V is represented by a peak in Vstep dI/dV. The height of the peak reflects the sharpness of the step and the width is equal to the step amplitude, ΔI. For the well-developed step, N = 671, both the height and the width of the peak are large. From Figure 5b, it can be seen that with decreasing N

• function of the number of active junctions, N. Blue symbols are measured directly from the I–V characteristics, and orange symbols are obtained by integration of the resonant peak area in dI/dV. (c) Simultaneous transport and detection measurements of a secondary resonance from Figure 7a. (d) Step

From a free electron gas to confined states: A mixed island of PTCDA and copper phthalocyanine on Ag(111)

• Alfred J. Weymouth,
• Emily Roche and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2022, 13, 1572–1577, doi:10.3762/bjnano.13.131

• gas (2DEG). We investigated mixed islands of PTCDA and copper phthalocyanine (CuPc) to study the change in the electronic state with the addition of an electron donor. We no longer observe a 2DEG state and instead identify states at 0.46 and 0.79 V. While one state appears in dI/dV images as an array

• of one-dimensional quantum wells, our analysis shows that this state does not act as a free electron gas and that the features are instead localized above individual PTCDA molecules. Keywords: AFM; copper phthalocyanine; dI/dV; PTCDA; STM; Introduction Organic semiconductor devices typically

• spectroscopy experiments [6][7][8], and has been studied with density functional theory (DFT) [9][10]. Previous work [11] has used dI/dV spectroscopy as a measurement of the density of electronic states [12] and identified this interface state starting at 0.6 eV. One characteristic of a two-dimensional

Induced electric conductivity in organic polymers

• Konstantin Y. Arutyunov,
• Anatoli S. Gurski,
• Vladimir V. Artemov,
• Alexander L. Vasiliev,
• Azat R. Yusupov,
• Danfis D. Karamov and
• Alexei N. Lachinov

Beilstein J. Nanotechnol. 2022, 13, 1551–1557, doi:10.3762/bjnano.13.128

• characteristics of each lead electrode separately. To measure differential characteristics dI/dV(V), modulation technique and phase-sensitive lock-in detection were used. To suppress the negative effect of stray electromagnetic pickups, a multistage RLC filter system was used [17]. While R(T) measurements at

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

Experimental and theoretical study of field-dependent spin splitting at ferromagnetic insulator–superconductor interfaces

• Peter Machon,
• Michael J. Wolf,
• Detlef Beckmann and
• Wolfgang Belzig

Beilstein J. Nanotechnol. 2022, 13, 682–688, doi:10.3762/bjnano.13.60

• a Si(111) substrate heated to 800 °C. In a second fabrication step, aluminium/aluminium oxide/copper tunnel junctions were fabricated on the EuS film using e-beam lithography and shadow evaporation. The nominal aluminium film thickness was d = 10 nm. The differential conductance g = dI/dV of the

Local stiffness and work function variations of hexagonal boron nitride on Cu(111)

• Abhishek Grewal,
• Yuqi Wang,
• Matthias Münks,
• Klaus Kern and
• Markus Ternes

Beilstein J. Nanotechnol. 2021, 12, 559–565, doi:10.3762/bjnano.12.46

• 6.1 eV [35], which can be modulated by the Moiré pattern [30]. We analyse the substrate using STM topography, dI/dV, and frequency shift, Δf, AFM maps under low (in-gap) and high (conduction band onset) bias conditions (see Figure 2). Due to h-BN being insulating, no spectroscopic contribution is

• . These distorted IPSs are referred as FER, which are revealed in dI/dV measurements as strong peaks at positive bias. [43]. Figure 3a shows such spectra in which we observe a series of peaks whose energies are strongly influenced by the measurement position. The non-trivial double peak structure at 3.5

• measurements are taken by modulating V (fm = 607 Hz, Vm = 10 mV peak-to-peak) and detecting the dI/dV signal with the lock-in technique while the tip height is adjusted so that the current I remains constant (constant-current mode) during the bias sweep. For KPFM measurements we stabilise the tip height at I

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

• , the electronic structure of the functionalized pyrene derivatives 1–3 on hBN/Cu(111) was addressed. Specifically, we performed bias-dependent STM imaging and dI/dV spectroscopy to probe the influence of the substitution, in conjunction with the distinct assemblies, on the molecular electronic states

• . Additionally, the role of the electronic landscape of the hBN/Cu(111) support, inducing a periodic modulation of the pyrene electronic structure via site-selective gating, is highlighted. Figure 5 shows a series of dI/dV spectra recorded above the molecular centers of the pyrene derivative 1 (Figure 5b), 2

• of well-defined, narrow molecular resonances and large HOMO–LUMO gaps evidenced a reduction of the electronic molecule–support interactions by the hBN spacer layer, as previously reported for adsorbates on hBN/Cu(111) [28][35][36][37][38] and other hBN/metal supports [18][19][20][79][80]. The dI/dV

Atomic defect classification of the H–Si(100) surface through multi-mode scanning probe microscopy

• Jeremiah Croshaw,
• Thomas Dienel,
• Taleana Huff and
• Robert Wolkow

Beilstein J. Nanotechnol. 2020, 11, 1346–1360, doi:10.3762/bjnano.11.119

• sample [9], while another reported they could be picked up from the surface during filled-states STM imaging [26]. Additional examples of the H removal along with STM I(V) and dI/dV spectroscopy of the neutral point defect can be seen in Supporting Information File 1, Figures S16 and S17. This evidence

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

• -covered Ir(111) [9] have been reported so far. In these studies molecular orbitals, the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO), appear with spectroscopic fine structure in differential conductance (dI/dV, I: tunneling current, V: bias voltage) data

• ) the observations are compatible with a reduced hybridization since compact molecular islands with a regular superstructure form and vibronic progression of the HOMO dI/dV spectroscopic signature is visible. Unoccupied molecular orbitals, however, appear as broad and merged resonances without

• indication of a vibronic fine structure. The molecular superstructure on graphene is similar to the assembly on Au(111), albeit with a lower molecule surface density, and dI/dV data exhibit vibronic progression in both frontier orbitals, which reflects the effective separation of C42H28 from the metal

Monolayers of MoS₂ on Ag(111) as decoupling layers for organic molecules: resolution of electronic and vibronic states of TCNQ

• Asieh Yousofnejad,
• Gaël Reecht,
• Nils Krane,
• Christian Lotze and
• Katharina J. Franke

Beilstein J. Nanotechnol. 2020, 11, 1062–1071, doi:10.3762/bjnano.11.91

• 4.6 K. Differential conductance (dI/dV) maps and spectra were recorded with a lock-in amplifier at modulation frequencies of 812–921 Hz, with the amplitudes given in the figure captions. Characterization of single-layer MoS2 on Ag(111) Figure 1a presents an STM image of the Ag(111) surface after the

• moiré pattern bears a topographic and an electronic modulation [38], we investigate the differential conductance (dI/dV) spectra on different locations (Figure 1d). We first examine the spectrum on the top site of the moiré structure. We observe a gap in the density of states, which is flanked by an

• measurements further showed that the shift also included band distortions, such that bands at Q were crossing EF (instead of at K). The band distortion was explained by hybridization of the WS2 bands with the Ag substrate [33]. As our dI/dV signal is not sensitive to k∥, we would not be able to detect band

Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field

• Levente Máthé and
• Ioan Grosu

Beilstein J. Nanotechnol. 2020, 11, 225–239, doi:10.3762/bjnano.11.17

• the spin-dependent differential conductance dI/dV = ΣσdIσ/dV] as a function of the bias voltage (eV = μL − μR) at three different temperatures and zero magnetic field. The zero-bias peak is observed when the difference in chemical potentials is equal to the Zeeman energy, eV = Δµ = Δεd = 0. The zero

• = −0.068. Differential conductance dI/dV as a function of the bias voltage eV with μR/D = −0.022 at three different temperatures in absence of a magnetic field. The remaining parameters are the same as those in Figure 3b. Differential conductance dI/dV as a function of the bias voltage eV for different

• magnetic field. The remaining parameters are the same as those in Figure 5. Differential conductance dI/dV as a function of the bias voltage eV for different values of the Zeeman energy at temperature T/D = 5 × 10−6. The remaining parameters are the same as those in Figure 5. The nonequilibrium DOS in 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

• spectroscopy (IETS) close to the Fermi level. The differential conductance (dI/dV) spectrum (Figure 2e) reveals a prominent sharp peak close to the zero-bias voltage and two side peaks corresponding to step-like increases in the dI/dV signal (labeled ΔG) at threshold voltages |Vth| = 110 ± 5 meV. This is a

• typical signature for an inelastic electron tunneling process involving the excitation of molecular vibration modes [5][22]. The IETS features are asymmetric in intensity with respect to the Fermi energy and will be discussed shortly at the end of this section. There are significant changes in the dI/dV

• been taken with the molecule attached to the tip by its ligand moiety (see Figure 2f). Therefore, the spectra have been aquired with different set points and the conductances cannot be compared directly. However, it is clear that the dI/dV spectrum of Figure 2e when the MnPc molecule is suspended in

Apparent tunneling barrier height and local work function of atomic arrays

• Neda Noei,
• Alexander Weismann and
• Richard Berndt

Beilstein J. Nanotechnol. 2018, 9, 3048–3052, doi:10.3762/bjnano.9.283

• topographs and from a characteristic signature in differential conductance (dI/dV) spectra. As first reported by Fölsch et al., short single-atom Cu chains on Cu(111) exhibit an unoccupied resonance at 1.5 eV above the Fermi energy EF [36]. Closely related data including the limit of very long chains were

Interaction-induced zero-energy pinning and quantum dot formation in Majorana nanowires

• Samuel D. Escribano,
• Alfredo Levy Yeyati and
• Elsa Prada

Beilstein J. Nanotechnol. 2018, 9, 2171–2180, doi:10.3762/bjnano.9.203

• in some dI/dV experiments, which exhibit substantial deviations from the predictions of simple models for finite length wires. On the other hand, and more importantly, the self-consistent solution of the electrostatic potential varies nonhomogeneously along the wire. It is relatively flat in the

Electronic conduction during the formation stages of a single-molecule junction

• Atindra Nath Pal,
• Tal Klein,
• Ayelet Vilan and
• Oren Tal

Beilstein J. Nanotechnol. 2018, 9, 1471–1477, doi:10.3762/bjnano.9.138

• to the vibration energy and its height is equal to the inelastic conductance contribution to the overall conductance across the junction. Figure 2a shows a differential conductance curve (dI/dV vs V) taken across a Ag–vanadocene junction with a zero-voltage conductance of ≈0.6 G0. The observed

• ) junctions. The traces are shifted for clarity. (a) Differential conductance vs applied voltage (dI/dV vs V) spectra measured at ≈0.6 G0 zero-voltage conductance after the introduction of vanadocene to the Ag junction. The steps in the conductance curve that are considered in the text are marked by arrows

• . Additional steps at higher voltage (not marked) can be seen as well. (b) Histogram of the number of times that a step feature at a certain applied voltage appears in dI/dV vs V spectra measured on different realizations of Ag–vanadocene junctions (544 spectra were analyzed in the context of step voltage). (c

Disorder-induced suppression of the zero-bias conductance peak splitting in topological superconducting nanowires

• Jun-Tong Ren,
• Hai-Feng Lü,
• Sha-Sha Ke,
• Yong Guo and
• Huai-Wu Zhang

Beilstein J. Nanotechnol. 2018, 9, 1358–1369, doi:10.3762/bjnano.9.128

• differential conductance G = dI/dV as a function of the bias voltage V under the influence of different types of disorder. (a,d) disorder δμ in the chemical potential; (b,e) disorder δt in the nearest hopping; (c,f) disorder δΔ in pairing energy. The upper panels corresponds to the shorter wire case L = 0.6 μm

• and the lower panels represents the case of L = 0.95 μm. Other parameters are taken as those used in Figure 2. The differential conductance G = dI/dV in the longer wire (L = 0.95 μm) as a function of the bias voltage V with δμ = δΔ = δt = 0.8 meV approaching the critical Zeeman splitting VZC = 0.9 meV

Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions

• Youngsang Kim,
• Safa G. Bahoosh,
• Dmytro Sysoiev,
• Thomas Huhn,
• Fabian Pauly and
• Elke Scheer

Beilstein J. Nanotechnol. 2017, 8, 2606–2614, doi:10.3762/bjnano.8.261

• the lock-in technique [15][19][20]. In this study, the second derivative (d2I/dV2) is measured simultaneously with the differential conductance (dI/dV) by means of two lock-in amplifiers. The second derivative is normalized with dI/dV to compensate for the conductance change. Thus the IET spectroscopy

• amplitude is defined as (d2I/dV2)/(dI/dV) [19]. IET measurements were performed, when the samples exhibit single-molecule junctions, as signaled by conductance values in the lowest conductance plateau. As can be seen in Figure 3a and 3b, twelve IET spectra were measured on open and closed forms

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

• values of Φ then Pb areas, in full agreement with the experimental results. To shed light on electronic properties, we provide a comparison of the measured dI/dV characteristics and calculated density of states (DOS) in Figure 5. Again, the theoretical results reproduce well the experimental data. The

• Pb ΔμPb measured with respect to its bulk value . (a) Top and (b), (c) side views of the 5hex model in the presence of Pb atoms (shown in green). (d) Local distribution of the electrostatic potential in the vacuum region. (a) dI/dV point spectroscopy data acquired on top of the Si NR. (b) Total

Transport characteristics of a silicene nanoribbon on Ag(110)

• Ryoichi Hiraoka,
• Chun-Liang Lin,
• Kotaro Nakamura,
• Ryo Nagao,
• Maki Kawai,
• Ryuichi Arafune and
• Noriaki Takagi

Beilstein J. Nanotechnol. 2017, 8, 1699–1704, doi:10.3762/bjnano.8.170

• SiNR from the substrate electronic system and elucidate the intrinsic properties. We measure the differential conductance (dI/dV) spectra of the nanojunctions and find a sharp peak structure at the Fermi level. Results and Discussion Figure 1a shows a topographic STM image of the Ag(110) surface after

• results are nicely matched with those reported in the previous STM works [25][26]. We measured dI/dV spectra as a function of the STM tip location. Figure 2a,b shows the spectra measured in the narrow and wide voltage ranges. One sees that these spectra are very similar to each other and do not depend on

• SiNR and measure the dI/dV spectrum at certain tip position. Figure 3b is an example of the conductance traces where the value of G is plotted as a function of Z. From the initial set point A to the point B, G increases as Z increases in the approaching procedure. The variation of G in this region is

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

• the pentacene molecules were probed by measuring the differential conductance (dI/dV) in STS experiments. In STS, pentacene reveals two molecular orbitals near the Fermi energy of the substrate, one at negative (−2.1 V) and one at positive bias voltage (+1.2 V) (Figure 2). The absolute peak positions

• adsorption geometries inside the h-BN valley (U = −1 V, I = 50 pA). c) Representation of the molecular geometry of a free pentacene molecule. STS of pentacene on h-BN/Rh(111) showing the resonances of the frontier molecular orbitals. The red curve depicts the dI/dV of bare h-BN. Zero bias refers to the Fermi

Stable Au–C bonds to the substrate for fullerene-based nanostructures

• Taras Chutora,
• Jesús Redondo,
• Bruno de la Torre,
• Martin Švec,
• Pavel Jelínek and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 1073–1079, doi:10.3762/bjnano.8.109

• features in the former energy gap. Identifying individual peaks and comparing them with C60 is more difficult but the occupied part of the spectrum seems to have changed more than the empty states upon adsorption. Unfortunately, attempts to reliably measure at room temperature the dI/dV spectrum of

Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

• Jakub S. Prauzner-Bechcicki,
• Lukasz Zajac,
• Piotr Olszowski,
• Res Jöhr,
• Antoine Hinaut,
• Thilo Glatzel,
• Bartosz Such,
• Ernst Meyer and
• Marek Szymonski

Beilstein J. Nanotechnol. 2016, 7, 1642–1653, doi:10.3762/bjnano.7.156

• conformations – a planar, seen as a four-lobed feature, and a non-planar, seen as a two-lobed feature. Additionally, these conformations differ in their dI/dV spectra, i.e., the non-planar shows the LUMO resonance at positive sample bias, and the planar shows the HOMO resonance at negative sample bias. The

Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

• Riccardo Frisenda,
• Mickael L. Perrin and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 2477–2484, doi:10.3762/bjnano.6.257

• become more evident when looking at the differential conductance (dI/dV) or the d2I/dV2, where they show up as steps, or peaks (dips), respectively. In this manuscript, when dealing with experimental data, we call IETS spectra the d2I/dV2/(dI/dV) signals calculated from the IV characteristics. Here, we

• shows up as a kink in the IV (upper panel), a step in the dI/dV (middle panel), and a peak in d2I/dV2 (lower panel). (c) Schematic illustration of the MCBJ technique. The large green arrow indicate the force to bend the sample. The small arrows illustrate the attenuated electrode displacement. The inset

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• of excited states of the molecule. This has already been discussed in a previous work [27] and will not be of further interest here. Transport simulations at finite magnetic fields In Figure 5 we show the splitting of the anionic resonance with applied magnetic field in a dI/dV map. In the upper

• -state transition which can be definitely assigned to a line in the lower panel in Figure 5. Figure 6 finally shows dI/dV maps as a function of the angle θ between the magnetic field and the z-axis. Panels (a), (b) and (c) show results obtained with vanishing SOI and panels (d), (e) and (f) are for

• ), the influence of SOI can be clearly seen. While for vanishing SOI any anisotropy of the dI/dV map is hidden beneath the temperature broadening, for finite SOI a slight θ-dependence can be observed. For B = 3 T, now also in the vanishing SOI case, Figure 6b, a slight anisotropy due to the orbital