Crystallographic orientation dependence of work function: carbon adsorption on Au surfaces

Jooya, Hossein Z.; 詯), X. Fan (言; McKay, Kyle S.; Pappas, David P.; Hite, D. A.; Sadeghpour, H. R.

doi:10.1080/00268976.2019.1603409

Cited by 11 publications

(9 citation statements)

References 28 publications

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“…However, for a more realistic model at larger length scales (and potentially including additional interaction effects), additional surface structures would need proper accounting: it is likely that adsorbates traversing such uneven surfaces would generate additional (rare) dipole fluctuations and, consequently, low-frequency electric-field noise. Even different smooth surfaces can have noticeable variation in surface dipole profiles, as recent theoretical work on carbon adsorbed on gold demonstrated [57]. Lastly, throughout this work, we have relied upon the patch potential model to link dipole fluctuations to trap noise even though it is only one approximate model of many potential models for this noise [32].…”

Section: Discussionmentioning

confidence: 99%

1/ω electric-field noise in surface ion traps from correlated adsorbate dynamics

et al. 2022

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Ion traps are promising architectures for implementing quantum computers, but they suffer from excessive "anomalous" ion motional heating that limit their overall coherence and practicality for scalable quantum computing. The exact microscopic origins of anomalous heating remain an open question, but experiments point to adsorbates on trap electrodes as one likely source. Many different models of anomalous heating have been proposed, but these models have yet to pinpoint the atomistic origin of the experimentally-observed 1/ω electric field noise scaling seen in ion traps at frequencies between 0.1-10 MHz. In this work, we show that a model based on previously-proposed surface-induced dipole fluctuations on adsorbates, but which also incorporates interparticle interaction dynamics through molecular dynamics simulations of up to multiple monolayers of adsorbates, gives rise to 1/ω frequency scaling at the MHz frequencies typically employed in ion traps. These results demonstrate that moderate-to-high densities of adsorbates can give rise to a set of activated motions that produce the 1/ω noise observed in ion traps and that collective adsorbate motions produce the observed noise spectra that a non-interacting model does not capture.

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Section: Discussionmentioning

confidence: 99%

1/ω electric-field noise in surface ion traps from correlated adsorbate dynamics

et al. 2022

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“…We ascribe the different observed yield strengths to local surface modifications introduced during SEM imaging, i.e., carbon deposition which is known to cause a change of surface properties, e.g., the work function of gold. 27 Also note that the photoemission pattern in Figure 2b shows a slight (∼10°) rotation with respect to the nominal slit orientation detected with SEM. Imperfect adjustments of the magnetic lenses in the PEEM can lead to similar distortions, but also a near-by edge of the sample holder aperture resulting in a surface potential deformation is a conceivable origin of this observation.…”

mentioning

confidence: 80%

“…For these two slits the PEEM yield is magnified by a factor of 8 in Figure b to match the signal level to that of the three leftmost slits. We ascribe the different observed yield strengths to local surface modifications introduced during SEM imaging, i.e., carbon deposition which is known to cause a change of surface properties, e.g., the work function of gold . Also note that the photoemission pattern in Figure b shows a slight (∼10°) rotation with respect to the nominal slit orientation detected with SEM.…”

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confidence: 90%

Spatial Variations in Femtosecond Field Dynamics within a Plasmonic Nanoresonator Mode

et al. 2019

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Plasmonic resonators can be designed to support spectrally well-separated discrete modes. The associated characteristic spatial patterns of intense electromagnetic hot-spots can be exploited to enhance light−matter interaction. Here, we study the local field dynamics of individual hot-spots within a nanoslit resonator by detecting characteristic changes of the photoelectron emission signal on a scale of ∼12 nm using time-resolved photoemission electron microscopy (TR-PEEM) and by excitation with the output from a 20 fs, 1 MHz noncollinear optical parametric amplifier (NOPA). Surprisingly, we detect apparent spatial variations of the Q-factor and resonance frequency that are commonly considered to be global properties for a single mode. By using the concept of quasinormal modes we explain these local differences by crosstalk of adjacent resonator modes. Our findings are important in view of timedomain studies of plasmon-mediated strong light−matter coupling at ambient conditions.

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“…Finally, histograms of Kelvin probe force microscopy (KPFM) images are presented to elucidate the surface-potential "roughness" of incrementally sputtered electroplated gold electrodes, quantifying work-function patch sizes with wide distributions of work functions on the electrode surface. These resulting work-function distributions are not fully explained by the different crystalline orientations within the polycrystalline electrode [24] but may also be the result of morphological effects of an unannealed surface. Finally, a simple model is presented to qualitatively explain a correlation between the nonmonotonic heating rates and the roughness of the surface-potential maps.…”

Section: Introductionmentioning

confidence: 95%

Surface science motivated by heating of trapped ions from the quantum ground state

Hite,

McKay,

Pappas

2021

Preprint

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For the past two and a half decades, anomalous heating of trapped ions from nearby electrode surfaces has continued to demonstrate unexpected results. Caused by electric-field noise, this heating of the ions' motional modes remains an obstacle for scalable quantum computation with trapped ions. One of the anomalous features of this electric-field noise is the reported nonmonotonic behavior in the heating rate when a trap is incrementally cleaned by ion bombardment. Motivated by this result, the present work reports on a surface analysis of a sample ion-trap electrode treated similarly with incremental doses of Ar + ion bombardment. Kelvin probe force microscopy and x-ray photoelectron spectroscopy were used to investigate how the work functions on the electrode surface vary depending on the residual contaminant coverage between each treatment. It is shown that the as-fabricated Au electrode is covered with a hydrocarbon film that is modified after the first treatment, resulting in work functions and core-level binding energies that resemble that of atomic-like carbon on Au. The change in the spatial distributions of work functions as the coverage changes with each treatment is apparently related to the nonmonotonic heating-rate behavior previously reported.

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Crystallographic orientation dependence of work function: carbon adsorption on Au surfaces

Cited by 11 publications

References 28 publications

1/ω electric-field noise in surface ion traps from correlated adsorbate dynamics

1/ω electric-field noise in surface ion traps from correlated adsorbate dynamics

Spatial Variations in Femtosecond Field Dynamics within a Plasmonic Nanoresonator Mode

Surface science motivated by heating of trapped ions from the quantum ground state

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