The role of interorbital interference in the formation of STS spectra

Jurczyszyn, L.; Stankiewicz, B.

doi:10.1016/j.apsusc.2004.07.066

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…This way the interference of the sample orbitals and interference between sample and tip orbitals can be investigated as well. A similar decomposition of tunneling matrix elements has been used by Jurczyszyn and Stankiewicz [20,21] and Mingo et al [4].…”

Section: Revised Chen's Derivative Rulementioning

confidence: 99%

“…extensively investigated inter-orbital interference effects in various tip-sample combinations and found that the interference has a considerable influence on STM images and STS spectra [4,20,21]. Sachse et al showed that an antiferromagnetic alignment of Mn spin moments in a Mn 2 H complex on the Ag(111) surface explains the experimental STM observation of a dip above the middle of the Mn dimer [22].…”

Section: Introductionmentioning

confidence: 99%

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Chen's derivative rule revisited: Role of tip-orbital interference in STM

Mándi

Palotás

2015

Phys. Rev. B

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On the occasion of its 25th anniversary, we revise Chen's derivative rule for electron tunneling [C.J. Chen, Phys. Rev. B 42, 8841 (1990)] for the purpose of computationally efficient simulations of scanning tunneling microscopy (STM) based on first principles electronic structure data. The revised model allows the weighting of tunneling matrix elements of different tip orbital characters by an arbitrary energy independent choice or based on energy dependent weighting coefficients obtained by an expansion of the tip single electron wavefunctions/density of states projected onto the tip apex atom. Tip-orbital interference in the STM junction is included in the model by construction and can be analyzed quantitatively. As a further advantage, arbitrary tip geometrical orientations are included in the revised model by rotating the coordinate system of the tip apex using Euler angles and redefining the weighting coefficients of the tunneling matrix elements. We demonstrate the reliability of the model by applying it to two functionalized surfaces of recent interest where quantum interference effects play an important role in the STM imaging process: N-doped graphene and a magnetic Mn 2 H complex on the Ag(111) surface. We find that the proposed tunneling model is 25 times faster than the Bardeen method concerning computational time, while maintaining good agreement. Our results show that the electronic structure of the tip has a considerable effect on STM images, and the Tersoff-Hamann model does not always provide sufficient results in view of quantum interference effects. For both studied surfaces we highlight the importance of interference between s and p z tip orbitals that can cause a significant contrast change in the STM images. Our method, thus, provides a fast and reliable tool for calculating STM images based on Chen's derivative rule taking into account the electronic structure and local geometry of the tip apex.

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Section: Revised Chen's Derivative Rulementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chen's derivative rule revisited: Role of tip-orbital interference in STM

Mándi

Palotás

2015

Phys. Rev. B

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“…Jurczyszyn and Stankiewicz [ 11 ] calculated the electronic structure of the sample surface by using the self-consistent, local consistent atomic orbital (LCAO) method. The LCAO Hamiltonian contains two contributions—the one-electron part, Ĥ oe , and the many-body part, Ĥ mb .…”

Section: Theorymentioning

confidence: 99%

“…Jurczyszyn and Stankiewicz [ 11 ] found that the size of the tunneling current between the tip and the sample does not solely depend on the energy and shape of the orbital directly involved in the tunneling process. The size was also modified by the destructive or constructive interferences of inter-atomic orbitals (especially s-p z interferences).…”

Section: Theorymentioning

confidence: 99%

Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

Knutsen

2010

Materials

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The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM) is investigated. The alkaline oxygen evolution reaction (OER) was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS) in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

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“…The improvement of the lateral resolution of the SPM to the picometer scale [7,[22][23][24][57][58][59][60], observation of orbital channels in tunneling conductance [61], and subatomic contrast in SPM experiments [22][23][24][25][26][27][28][29][30][31][32] led to the development of new theories accounting for the distance dependence of the electron orbital contribution [62,63], energy-dependent combinations of the tip orbitals [64][65][66][67][68], and effects of inter-and intra-atomic interference of the electron orbitals in the tunneling junction [69][70][71][72][73]. Recently, the revised Chen's derivative rule, accounting for the orbital interference effects, has been proposed by Mandi and Palotas [74], who considered the realistic electronic structure and arbitrary spatial orientation of the tip minimizing the computational efforts.…”

Section: Introductionmentioning

confidence: 99%

Electron Orbital Contribution in Distance‐Dependent STM Experiments

Чайка¹

2016

Microscopy and Analysis

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Scanning tunneling microscopy (STM) is one of the most powerful techniques for the analysis of surface reconstructions at the atomic scale. It utilizes a sharp tip, which is brought close to the surface with a bias voltage applied between the tip and the sample. The value of the tunneling current, flowing between the tip and the sample, is determined by the structure of the surface and the tip, the bias voltage, and the tipsample distance. By scanning the tip over the surface, a tunneling current map is produced, which reflects the local atomic and electronic structures. This chapter focuses on the role of the tip-surface distance in ultrahigh vacuum STM experiments with atomic and subatomic resolution. At small distances, i.e., comparable with interatomic distances in solids, the interaction between the tip and the surface atoms can modify their electronic structure changing the symmetry of the atomically resolved STM images and producing unusual features at the subatomic scale. These features are related to changes of the relative contribution of different electron orbitals of the tip and the surface atoms at varying distances.

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The role of interorbital interference in the formation of STS spectra

Cited by 4 publications

References 11 publications

Chen's derivative rule revisited: Role of tip-orbital interference in STM

Chen's derivative rule revisited: Role of tip-orbital interference in STM

Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

Electron Orbital Contribution in Distance‐Dependent STM Experiments

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