Two-dimensional polyaniline (C3N) from carbonized organic single crystals in solid state

The formation of 2D polyaniline (PANI) has attracted considerable interest due to its expected electronic and optoelectronic properties. Although PANI was discovered over 150 y ago, obtaining an atomically well-defined 2D PANI framework has been a longstanding challenge. Here, we describe the synthesis of 2D PANI via the direct pyrolysis of hexaaminobenzene trihydrochloride single crystals in solid state. The 2D PANI consists of three phenyl rings sharing six nitrogen atoms, and its structural unit has the empirical formula of C3N. The topological and electronic structures of the 2D PANI were revealed by scanning tunneling microscopy and scanning tunneling spectroscopy combined with a first-principle density functional theory calculation. The electronic properties of pristine 2D PANI films (undoped) showed ambipolar behaviors with a Dirac point of –37 V and an average conductivity of 0.72 S/cm. After doping with hydrochloric acid, the conductivity jumped to 1.41 × 103 S/cm, which is the highest value for doped PANI reported to date. Although the structure of 2D PANI is analogous to graphene, it contains uniformly distributed nitrogen atoms for multifunctionality; hence, we anticipate that 2D PANI has strong potential, from wet chemistry to device applications, beyond linear PANI and other 2D materials.

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Imaging and identification of point defects in PtTe2

npj 2D Materials and Applications ◽

10.1038/s41699-020-00196-8 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Kuanysh Zhussupbekov ◽

Lida Ansari ◽

John B. McManus ◽

Ainur Zhussupbekova ◽

Igor V. Shvets ◽

...

Keyword(s):

Point Defects ◽

Density Functional ◽

Transition Metal Dichalcogenides ◽

Density Functional Theory Calculations ◽

Charge Carrier Mobility ◽

Scanning Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Recombination Rates ◽

And Performance

AbstractThe properties and performance of two-dimensional (2D) materials can be greatly affected by point defects. PtTe2, a 2D material that belongs to the group 10 transition metal dichalcogenides, is a type-II Dirac semimetal, which has gained a lot of attention recently due to its potential for applications in catalysis, photonics, and spintronics. Here, we provide an experimental and theoretical investigation of point defects on and near the surface of PtTe2. Using scanning tunneling microscopy and scanning tunneling spectroscopy (STS) measurements, in combination with first-principle calculations, we identify and characterize five common surface and subsurface point defects. The influence of these defects on the electronic structure of PtTe2 is explored in detail through grid STS measurements and complementary density functional theory calculations. We believe these findings will be of significance to future efforts to engineer point defects in PtTe2, which is an interesting and enticing approach to tune the charge-carrier mobility and electron–hole recombination rates, as well as the site reactivity for catalysis.

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Nanoparticle characterization based on STM and STS

Chemical Society Reviews ◽

10.1039/c4cs00204k ◽

2015 ◽

Vol 44 (4) ◽

pp. 970-987 ◽

Cited By ~ 45

Author(s):

Shinya Kano ◽

Tsukasa Tada ◽

Yutaka Majima

Keyword(s):

Solid State ◽

Scanning Tunneling Microscopy ◽

Scanning Tunneling Spectroscopy ◽

Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Nanoparticle Characterization

Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can characterize intriguing nanoparticle properties towards solid-state nanodevices.

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Scanning Tunneling Spectroscopy in Anisotropic s-Wave Superconductors

International Journal of Modern Physics B ◽

10.1142/s0217979203020892 ◽

2003 ◽

Vol 17 (18n20) ◽

pp. 3300-3303 ◽

Cited By ~ 1

Author(s):

H. Suderow ◽

J. G. Rodrigo ◽

P. Martinez-Samper ◽

S. Vieira ◽

J. P. Brison ◽

...

Keyword(s):

Scanning Tunneling Microscopy ◽

Single Crystals ◽

Low Temperatures ◽

Scanning Tunneling Spectroscopy ◽

Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Superconducting Gap ◽

S Wave ◽

Tunneling Microscopy

We discuss Scanning Tunneling Microscopy and Spectroscopy (STM/S) measurements at very low temperatures in single crystals of the non magnetic borocarbide superconductors RNi 2 B 2 C ( R = Y , Lu , T c=15.5 and 16.5 K) and in MgB 2. The tunneling spectra in some regions of the surface show a clear reduction of the anisotropy of the superconducting gap.

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Point-contact Andreev reflection spectroscopy on Bi2Se3 single crystals

International Journal of Modern Physics B ◽

10.1142/s0217979216420029 ◽

2016 ◽

Vol 30 (13) ◽

pp. 1642002 ◽

Cited By ~ 2

Author(s):

C. R. Granstrom ◽

I. Fridman ◽

H.-C. Lei ◽

C. Petrovic ◽

J. Y. T. Wei

Keyword(s):

Single Crystals ◽

Andreev Reflection ◽

Surface Condition ◽

Three Dimensional ◽

Point Contact ◽

Scanning Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Zero Bias ◽

Zero Bias Conductance

To study how Andreev reflection (AR) occurs between a superconductor and a three-dimensional topological insulator (TI), we use superconducting Nb tips to perform point-contact AR spectroscopy at 4.2 K on as-grown single crystals of Bi2Se3. Scanning tunneling spectroscopy and scanning tunneling microscopy are also used to characterize the superconducting tip and both the doping level and surface condition of the TI sample. The point-contact measurements show clear spectral signatures of AR, as well as a depression of zero-bias conductance with decreasing junction impedance. The latter observation can be attributed to interfacial Rashba spin-orbit coupling, and the presence of bulk bands at the Fermi level in our samples suggests that bulk states of Bi2Se3 are involved in the observed AR.

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STM Spectroscopy of Star-Type Molecular Magnet

Dhaka University Journal of Science ◽

10.3329/dujs.v60i1.10343 ◽

2012 ◽

Vol 60 (1) ◽

pp. 87-91

Author(s):

MS Alam ◽

FA Chowdhury ◽

RW Saalfrank ◽

AV Postnikov ◽

P Müller

Keyword(s):

Single Molecule ◽

Density Functional ◽

Scanning Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Molecular Magnet ◽

Large Signal ◽

Tunneling Microscopy ◽

Functional Theory ◽

Metal Centers ◽

Stm Images

In order to achieve a better understanding of how scanning tunneling microscopy (STM) images of metallo-complexes are related to the geometric and electronic structure, we performed scanning microscopy (STM) and scanning tunneling spectroscopy (STS) techniques on [FeIIIFeIII 3L6] (L= N-methylaminediethanolate) star-type tetranuclear molecular magnet. The experiments were performed under ambient condition. We were able to image single molecule by STM with submolecular resolution. In our STS measurements we found a rather large signal at the positions of iron ion centers in the molecules. This direct addressing of metal centers was further confirmed by density functional theory (DFT) calculations.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10343 Dhaka Univ. J. Sci. 60(1): 87-91 2012 (January)

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Study of single molecules and their assemblies by scanning tunneling microscopy

Pure and Applied Chemistry ◽

10.1351/pac200678050905 ◽

2006 ◽

Vol 78 (5) ◽

pp. 905-933 ◽

Cited By ~ 2

Author(s):

J. G. Hou ◽

Kedong Wang

Keyword(s):

Scanning Tunneling Microscopy ◽

Density Functional ◽

Single Molecules ◽

Scanning Tunneling Spectroscopy ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Physical Problems ◽

The Density Functional Theory ◽

And Control ◽

Theoretical Simulations

The recent rapid advances in nanotechnology, especially those based on molecules, are due in large part to our newly acquired abilities to measure and manipulate individual molecules and their assemblies. Among all the approaches for the study of single molecules, scanning tunneling microscopy (STM) is unique and powerful owing to its ability to accurately probe and control single molecules. High-resolution spatial imaging combined with scanning tunneling spectroscopy (STS) helps scientists investigate and resolve many chemical and physical problems at the molecular level. In this paper, we review our recent studies of single molecules and their assemblies by combining STM experiments and theoretical simulations based on the density functional theory (DFT).

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Engineering the magnetism of nanographene via co-depositing hetero precursors

10.21203/rs.3.rs-595946/v1 ◽

2021 ◽

Author(s):

Hui Zhang ◽

Jianchen Lu ◽

Yong Zhang ◽

Lei Gao ◽

Xin-Jing Zhao ◽

...

Keyword(s):

Density Functional ◽

Carbon Nanomaterials ◽

Density Functional Theory Calculations ◽

Scanning Tunneling Spectroscopy ◽

Carbon Skeleton ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Molecular Precursors ◽

New Strategy ◽

Spin Number

Abstract The magnetism of carbon nanomaterials is dominated by the structure of its carbon skeleton. However, the magnetism engineering is hindered due to finite precursors. Here, we develop a new strategy to engineer the magnetism of nanographene through hetero-coupling two different precursors on Au(111) surface by using low-temperature bond-resolved scanning tunneling microscopy and scanning tunneling spectroscopy, combined with spin-polarized density functional theory calculations. Our results demonstrate that two homo-coupled products host close shell structure along with defects inducing magnetic one with the total spin number S = 1/2. Upon simultaneous depositing with another precursor, two hetero-coupled products switch to magnetic structure with the S = 1/2 and S = 1 resulting from carbon skeleton transformation. Our results provide a valid way via inducing different molecular precursors to engineer the magnetism of carbon nanomaterials, which could be extended in other magnetic materials instruction.

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LOCAL ELECTRONIC STATES ON TWO-DIMENSIONAL NANOSCALE ISLAND OF Si AND Ge FABRICATED ON Si(111) 7 × 7 SUBSTRATE

International Journal of Nanoscience ◽

10.1142/s0219581x09006444 ◽

2009 ◽

Vol 08 (06) ◽

pp. 595-603

Author(s):

YUKICHI SHIGETA ◽

RYOTA NEGISHI ◽

MASAHIKO SUZUKI

Keyword(s):

Electronic Structure ◽

Photoelectron Spectroscopy ◽

Density Functional ◽

Great Influence ◽

Energy Difference ◽

Scanning Tunneling Spectroscopy ◽

Local Deformation ◽

Scanning Tunneling ◽

Two Dimensional ◽

Tunneling Microscopy

Nanoscale islands on semiconductor are a strong candidate as building block in nanodevices. In the nanoisland, some local deformation is induced by the surface tension, which has a great influence on the electronic property of the nanoislands. To study the electronic structure of two-dimensional (2D) nanoislands of Si and Ge on the Si(111) 7 × 7 surface, we formed nanoislands of the same size and measured with angle resolved ultraviolet photoelectron spectroscopy (ARUPS), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). We found that the nanoisland shows a characteristic fine structure due to some strain. We also calculated a relation between the strain and electronic state based on the density-functional theory. In the calculation, the dangling-bond state at the strained adatom on the nanoisland (SR state) shifts to lower energy, which has liner dependence with the height of the adatoms. The ARUPS spectrum and the STS show characteristic peaks corresponding to the SR state, whose energy depends on the deformation of the adatom. The height of the adatom on the nanoisland estimated from the energy difference is consistent with a result of the STM measurement. The strain of adatoms can be estimated from the electronic structure.

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Dual role of CO in the stability of subnano Pt clusters at the Fe3O4(001) surface

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1605649113 ◽

2016 ◽

Vol 113 (32) ◽

pp. 8921-8926 ◽

Cited By ~ 64

Author(s):

Roland Bliem ◽

Jessi E. S. van der Hoeven ◽

Jan Hulva ◽

Jiri Pavelec ◽

Oscar Gamba ◽

...

Keyword(s):

Density Functional ◽

Elevated Temperatures ◽

Time Lapse ◽

Dual Role ◽

Oxidation Catalyst ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Active Metal ◽

Catalytically Active ◽

The Stability

Interactions between catalytically active metal particles and reactant gases depend strongly on the particle size, particularly in the subnanometer regime where the addition of just one atom can induce substantial changes in stability, morphology, and reactivity. Here, time-lapse scanning tunneling microscopy (STM) and density functional theory (DFT)-based calculations are used to study how CO exposure affects the stability of Pt adatoms and subnano clusters at the Fe3O4(001) surface, a model CO oxidation catalyst. The results reveal that CO plays a dual role: first, it induces mobility among otherwise stable Pt adatoms through the formation of Pt carbonyls (Pt1–CO), leading to agglomeration into subnano clusters. Second, the presence of the CO stabilizes the smallest clusters against decay at room temperature, significantly modifying the growth kinetics. At elevated temperatures, CO desorption results in a partial redispersion and recovery of the Pt adatom phase.

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