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

2020 ◽  
Vol 11 ◽  
pp. 1062-1071
Author(s):  
Asieh Yousofnejad ◽  
Gaël Reecht ◽  
Nils Krane ◽  
Christian Lotze ◽  
Katharina J Franke
Keyword(s):  
Energy Levels ◽  
Single Layer ◽  
Strong Interactions ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Strong Electron ◽  
Line Shapes ◽  
Structure Of Molecules ◽  
Lowest Unoccupied Molecular Orbital ◽  
Vibronic States

The electronic structure of molecules on metal surfaces is largely determined by hybridization and screening by the substrate electrons. As a result, the energy levels are significantly broadened and molecular properties, such as vibrations are hidden within the spectral line shapes. Insertion of thin decoupling layers reduces the line widths and may give access to the resolution of electronic and vibronic states of an almost isolated molecule. Here, we use scanning tunneling microscopy and spectroscopy to show that a single layer of MoS2 on Ag(111) exhibits a semiconducting bandgap, which may prevent molecular states from strong interactions with the metal substrate. We show that the lowest unoccupied molecular orbital (LUMO) of tetracyanoquinodimethane (TCNQ) molecules is significantly narrower than on the bare substrate and that it is accompanied by a characteristic satellite structure. Employing simple calculations within the Franck–Condon model, we reveal their vibronic origin and identify the modes with strong electron–phonon coupling.

Radical induced intermolecular linkage and energy level modifications of a porphyrin monolayer

2017 ◽  
Vol 53 (6) ◽  
pp. 1104-1107 ◽  
Author(s):  
Abdolreza Jahanbekam ◽  
Colin Harthcock ◽  
David Y. Lee
Keyword(s):  
Energy Level ◽  
Scanning Tunneling Microscopy ◽  
Surface Structure ◽  
Energy Levels ◽  
New Method ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Molecular Scale

A new method to directly modify the surface structure and energy levels of a porphyrin monolayer was examined with molecular-scale resolution using scanning tunneling microscopy and spectroscopy (STM and STS) and presented in this communication.

A New, Nearly Single-Domain Surface Structure of Homoepitaxial Diamondr (001) Films

1996 ◽  
Vol 423 ◽  
Author(s):  
Yalei Kuang ◽  
Naesung Lee ◽  
Andrzej Badzian ◽  
Teresa Badzian ◽  
Tien T. Tsong
Keyword(s):  
Surface Structure ◽  
Natural Diamond ◽  
Single Layer ◽  
Chemical Vapor ◽  
Single Domain ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Plasma Chemical Vapor Deposition ◽  
Boron Doped ◽  
Step Edges

AbstractBoron-doped homoepitaxial diamond films were grown on natural diamond (001) substrates using microwave-assisted plasma chemical vapor deposition techniques. The surface structures were investigated using scanning tunneling microscopy (STM). This showed a dimertype 2×1 reconstruction structure with single-layer steps where dimer rows on the upper terrace are normal to or parallel to the step edges. We found that dimer rows parallel to the step edges are much longer than those normal to the step edges. The nearly single-domain surface structure observed by STM is in agreement with the low-energy electron diffraction (LEED) patterns from these surfaces. The high atomic resolution STM image showed that the local 1×1 configurations exist.

scholarly journals The effect of moiré superstructures on topological edge states in twisted bismuthene homojunctions

2020 ◽  
Vol 6 (23) ◽  
pp. eaba2773 ◽  
Author(s):  
Jian Gou ◽  
Longjuan Kong ◽  
Xiaoyue He ◽  
Yu Li Huang ◽  
Jiatao Sun ◽  
...  
Keyword(s):  
Single Layer ◽  
Scanning Tunneling ◽  
Edge States ◽  
First Principles Calculations ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Spatially Distributed ◽  
Topological States ◽  
Device Applications

Creating and controlling the topological properties of two-dimensional topological insulators is essential for spintronic device applications. Here, we report the successful growth of bismuth homostructure consisting of monolayer bismuthene and single-layer black phosphorus–like Bi (BP-Bi) on the HOPG surface. Combining scanning tunneling microscopy/spectroscopy with noncontact atomic force microscopy, moiré superstructures with twist angles in the bismuth homostructure and the modulation of topological edge states of bismuthene were observed and studied. First-principles calculations reproduced the moiré superlattice and indicated that the structure fluctuation is ascribed to the stacking modes between bismuthene and BP-Bi, which induce spatially distributed interface interactions in the bismuth homostructure. The modulation of topological edge states is directly related to the variation of interlayer interactions. Our results suggest a promising pathway to tailor the topological states through interfacial interactions.

Single-layer MoS2formation by sulfidation of molybdenum oxides in different oxidation states on Au(111)

2017 ◽  
Vol 19 (21) ◽  
pp. 14020-14029 ◽  
Author(s):  
Norberto Salazar ◽  
Igor Beinik ◽  
Jeppe V. Lauritsen
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Single Layer ◽  
Oxidation States ◽  
Scanning Tunneling ◽  
Molybdenum Oxides ◽  
Tunneling Microscopy ◽  
X Ray

The sulfidation pathway from MoO3to MoS2on Au(111) revealed by a combination of Scanning Tunneling Microscopy and X-Ray Photoelectron Spectroscopy.

scholarly journals Evolution of quasi-bound states in the circular n–p junction of bilayer graphene under magnetic field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haijiao Ji ◽  
Yueting Pan ◽  
Haiwen Liu
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Bound States ◽  
Local Density ◽  
Energy Levels ◽  
Bilayer Graphene ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Weak Magnetic Fields ◽  
The Magnetic Field

Abstract Electron in gapless bilayer graphene can form quasi-bound states when a circular symmetric potential is created in bilayer graphene. These quasi-bound states can be adjusted by tuning the radius and strength of the potential barrier. We investigate the evolution of quasi-bound states spectra in the circular n–p junction of bilayer graphene under the magnetic field numerically. The energy levels of opposite angular momentum split and the splitting increases with the magnetic field. Moreover, weak magnetic fields can slightly shift the energy levels of quasi-bound states. While strong magnetic fields induce additional resonances in the local density states, which originates from Landau levels. We demonstrate that these numerical results are consistent with the semiclassical analysis based on Wentzel–Kramers–Brillouin approximation. Our results can be verified experimentally via scanning tunneling microscopy measurements.

scholarly journals ESPLORANDO “FLATLANDIA”: DAL GRAFENE ALLA SCOPERTA DI NUOVI MATERIALI BI-DIMENSIONALI

2020 ◽  
Author(s):  
Francesco Tumino
Keyword(s):  
Materials Science ◽  
2D Materials ◽  
Single Layer ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Bulk Materials ◽  
Molecular Sensing ◽  
Novel Technologies ◽  
Materials Research ◽  
First Time

The development of nanotechnology has encouraged the research of new nanomaterials for innovative applications. In 2004, the production and study of graphene — that is a single layer of carbon atoms — showed, for the first time, the extraordinary properties of this material and opened the way to the exploration of the so-called two-dimensional (2D) materials. Since then, several 2D materials have been produced and studied, revealing properties and behaviours, in general, very different from those of corresponding bulk materials. Research on 2D materials is nowadays one of the most active and promising fields of materials science, which is setting the basis for the development of novel technologies, such as in electronics, optoelectronics, energy and molecular sensing. In this paper, some important aspects of the study of 2D materials will be introduced — such as the synthesis methodologies and characterization techniques — and some of their properties will be shown, with the support of recent experimental results of scanning tunneling microscopy (STM) investigations.

Electrochemically Gated Long Distance Charge Transport in Photosystem I

2019 ◽  
Author(s):  
Montserrat López Martínez ◽  
Manuel López Ortiz ◽  
Maria Elena Antinori ◽  
Emilie Wientjes ◽  
Roberta Croce ◽  
...  
Keyword(s):  
Charge Transport ◽  
Photosystem I ◽  
Energy Levels ◽  
Hole Injection ◽  
Scanning Tunneling ◽  
Enzymatic Reactions ◽  
Tunneling Microscopy ◽  
Long Distance ◽  
Distance Measurements ◽  
Long Distance Transport

<p>The transport of electrons along photosynthetic and respiratory chains involves a series of enzymatic reactions that are coupled through redox mediators, including proteins and small molecules. The use of native and synthetic redox probes is key to understand charge transport mechanisms, and to design bioelectronic sensors and solar energy conversion devices. However, redox probes have limited tunability to exchange charge at the desired electrochemical potentials (energy levels) and at different protein sites. Here, we take advantage of electrochemical scanning tunneling microscopy (ECSTM) to control the Fermi energy and nanometric position of the ECSTM probe in order to study electron transport in individual photosystem I (PSI) complexes. Current-distance measurements at different potentiostatic conditions indicate that PSI supports long-distance transport that is electrochemically gated near the redox potential of P700, with current extending farther under hole injection conditions.</p>

Twisted charge-density-wave patterns in bilayer 2D crystals and modulated electronic states

2D Materials ◽  
2021 ◽  
Author(s):  
Yaoyao Chen ◽  
Liwei Liu ◽  
Xuan Song ◽  
Han Yang ◽  
zeping Huang ◽  
...  
Keyword(s):  
Charge Density ◽  
Density Wave ◽  
Single Layer ◽  
Interlayer Coupling ◽  
Charge Density Waves ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Atomic Lattices ◽  
Fresh Insight ◽  
2D Crystals

Abstract The twistronics of the atomic-thick two-dimensional (2D) van der Waals materials has opened a new venue to investigate the interlayer coupling. Till now, most studies focus on the twist of atomic lattices and the resulted moiré superstructures, while the reports about the twist of charge density waves (CDW), the superstructures of which are from individual layers are limited. Here, using molecular beam epitaxy, we construct bilayer (BL) 1T-NbSe2 vertical structures. With high resolution scanning tunneling microscopy observations, we identify two cases of CDW twisted stacking with atomic precision. The typical twist angles are 0o and 60o between the 1st and the 2nd layer, although the top Se atomic lattices of these two layers are parallel. Compared to the single layer case, the dI/dV at BL shows an insulator-to-metal transition, with the Hubbard bands shrinking towards the Fermi level (EF ). More intriguingly, interlayer coupling states rise near EF , which are dependent on the CDW twist angles. These findings give fresh insight into the engineering of 2D materials by CDW twisting and are potentially applicable for future nanoelectronic devices.

ELECTRONIC STRUCTURE AND STM IMAGE OF C60–C70 ADSORBED ON THE Cu(111) SURFACE

1996 ◽  
Vol 03 (01) ◽  
pp. 923-926
Author(s):  
YUTAKA MARUYAMA ◽  
KAORU OHNO ◽  
YOSHIYUKI KAWAZOE
Keyword(s):  
Molecular Orbital ◽  
Bias Voltage ◽  
Scanning Tunneling ◽  
Band Structure Calculation ◽  
Tunneling Microscopy ◽  
Highest Occupied Molecular Orbital ◽  
Voltage Dependent ◽  
Lowest Unoccupied Molecular Orbital ◽  
Adsorption Geometry ◽  
Stm Images

A recent scanning tunneling microscopy (STM) experiment has revealed that C 60–C70 mixture on the Cu (111)–(1×1) substrate shows specific bias-voltage-dependent images which reflect intramolecular structure. In order to understand this observation, we perform a band-structure calculation. In this study, we adopt a simple model assuming a two-dimensional (2D) molecular crystal and a proper adsorption geometry. By comparing the calculated charge distributions of the lowest unoccupied molecular orbital (LUMO)-induced bands and the highest occupied molecular orbital (HOMO)-induced bands with the observed STM images, we find that the shapes of the intramolecular structures which change with the bias voltage strongly reflect the positions of pentagonal and hexagonal rings.

Electrochemically Gated Long Distance Charge Transport in Photosystem I

2019 ◽  
Author(s):  
Montserrat López Martínez ◽  
Manuel López Ortiz ◽  
Maria Elena Antinori ◽  
Emilie Wientjes ◽  
Roberta Croce ◽  
...  
Keyword(s):  
Charge Transport ◽  
Photosystem I ◽  
Energy Levels ◽  
Hole Injection ◽  
Scanning Tunneling ◽  
Enzymatic Reactions ◽  
Tunneling Microscopy ◽  
Long Distance ◽  
Distance Measurements ◽  
Long Distance Transport

<p>The transport of electrons along photosynthetic and respiratory chains involves a series of enzymatic reactions that are coupled through redox mediators, including proteins and small molecules. The use of native and synthetic redox probes is key to understand charge transport mechanisms, and to design bioelectronic sensors and solar energy conversion devices. However, redox probes have limited tunability to exchange charge at the desired electrochemical potentials (energy levels) and at different protein sites. Here, we take advantage of electrochemical scanning tunneling microscopy (ECSTM) to control the Fermi energy and nanometric position of the ECSTM probe in order to study electron transport in individual photosystem I (PSI) complexes. Current-distance measurements at different potentiostatic conditions indicate that PSI supports long-distance transport that is electrochemically gated near the redox potential of P700, with current extending farther under hole injection conditions.</p>

Sign in / Sign up

Export Citation Format

Share Document