Secondary electron emission studies

Shih, A.; Yater, J.E.; Hor, C.; Abrams, R.H.

doi:10.1016/s0169-4332(96)00729-5

Cited by 168 publications

(89 citation statements)

References 12 publications

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“…Experimental studies so far have reported a change in the work function with opposite sign in double-layer LSMO [34] and in manganite grain boundaries [35]. We note that other "extrinsic" factors, such as absorption of surface contaminants upon exposure to air or during low-temperature vacuum measurements that are extended in time, could also contribute to changes of the work function from its value on a pristine surface [36].…”

Section: Iv4 Discussionmentioning

confidence: 86%

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

et al. 2014

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Knowledge of the electron sampling depth and related saturation effects is important for quantitative analysis of X-ray absorption spectroscopy data, yet for oxides with the perovskite structure no quantitative values are so far available. Here we study absorption saturation in films of two of the moststudied perovskites, La 0.7 Ca 0.3 MnO 3 (LCMO) and YBa 2 Cu 3 O 7 (YBCO), at the L 2,3 edge of Mn and Cu, respectively. By measuring the electron-yield intensity as a function of photon incidence angle and film thickness, the sampling depth d, photon attenuation length λ and the ratio λ/d have been independently determined between 50 and 300 K. The extracted sampling depth d LCMO ≈ 3 nm for LCMO at high temperatures in its polaronic insulator state (150 -300 K) is not much larger than values reported for pure transition metals (d Co or Ni ≈ 2 -2.5 nm) at room temperature, but is smaller than d YBCO ≈ 3.9 nm for metallic YBCO that is in turn smaller than the value reported for Fe 3 O 4 (d Fe3O4 ≈ 4.5 nm). The measured d LCMO increases to 4.5 nm when LCMO is in the metallic state at low temperatures. These results indicate that a universal rule of thumb for the sampling depth in oxides cannot be assumed, and that it can be measurably influenced by electronic phase transitions that derive from strong correlations.

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Section: Iv4 Discussionmentioning

confidence: 86%

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

et al. 2014

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“…It is well known that the oxides of metals produce high SEY due to the increase of the escape depth of the generated electron because of reduction in number electronelectron interactions [36,37]. However, even in this condition with the surface in an oxide state the SEY stays below 1 due the multiple trapping sites of the grooves and the possible reduced density of the submicron structure and nano-spheres which can have sizes very similar to the escape depth (50 nm) and the shadowing effect of adjacent submicron and nanostructures.…”

Section: Discussionmentioning

confidence: 99%

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

Valizadeh

Malyshev

Wang

et al. 2017

Applied Surface Science

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Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators. In our previous publications, a low SEY< 0.9 for as-received metal surfaces modified by a nanosecond pulsed laser was reported. In this paper, the SEY of laser-treated blackened copper has been investigated as a function of different laser irradiation parameters. We explore and study the influence of micro-and nano-structures induced by laser surface treatment in air of copper samples as a function of various laser irradiation parameters such as peak power, laser wavelength ( = 355 nm and 1064 nm), number of pulses per point (scan speed and repetition rate) and fluence, on the SEY. The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) which revealed that heating resulted in diffusion of oxygen into the bulk and induced the transformation of CuO to sub-stoichiometric oxide. The surface topography was examined with high resolution scanning electron microscopy (HRSEM) which showed that the laser-treated surfaces are dominated by microstructure grooves and nanostructure features.

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“…Electron illumination generates secondary and Auger electrons inside the thin samples during the TEM observations. When this is combined with poor electrical conductivity, positive charges can build up due to the escape of the secondary and Auger electrons from the sample (18,19,(22)(23)(24)(25). For Cu 2 S, the difference in the band gaps of the semiconducting L-s phase and the insulating H-i phase, meaning that their Fermi levels are at different energies, gives rise to drastic changes in the charge distribution throughout the nanoplate volumes during the electronbeam-radiation process.…”

Section: Significancementioning

confidence: 99%

“…On the other hand, in an electronic insulator, the escape depth for secondary and Auger electrons is widely accepted to be on the order of tens of nanometers (19,24,25), at least an order of magnitude larger than in a semiconducting phase. Assuming an exponential decay of the charge distribution along the incident-electronbeam direction (Fig.…”

Section: Significancementioning

confidence: 99%

Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S

Tao

Chen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The optimal functionalities of materials often appear at phase transitions involving simultaneous changes in the electronic structure and the symmetry of the underlying lattice. It is experimentally challenging to disentangle which of the two effects--electronic or structural--is the driving force for the phase transition and to use the mechanism to control material properties. Here we report the concurrent pumping and probing of Cu 2 S nanoplates using an electron beam to directly manipulate the transition between two phases with distinctly different crystal symmetries and charge-carrier concentrations, and show that the transition is the result of charge generation for one phase and charge depletion for the other. We demonstrate that this manipulation is fully reversible and nonthermal in nature. Our observations reveal a phase-transition pathway in materials, where electron-induced changes in the electronic structure can lead to a macroscopic reconstruction of the crystal structure. functional and quantum materials--the key properties of functional materials are often born out of strong structural and electronic interactions that are quantum mechanical in nature. Notable examples include colossal magnetoresistance manganites (1), ferroelectrics (2), and valleytronic materials (3). The targeted functions are usually accompanied by symmetry breaking, induced through changes in temperature or under other external perturbations. A prominent question is whether the symmetry reduction has an origin in the lattice (e.g., in the form of displacement of atoms, and could be described reasonably well using first-principles calculations) or the electronic degrees of freedom (charge, spin, and orbital) (4-6). It is of great interest to distinguish the roles of these factors in phase transitions.Cu 2 S provides an intriguing example for addressing the above "chicken-and-egg" question (6), which is critical to the understanding of a wide range of functional and quantum materials. It is a fast ionic conductor (7) with highly mobile Cu ions. A phase transition in the bulk material occurs near 100°C from a semiconducting (8) monoclinic symmetry low-chalcocite phase (9) [hereafter called the "L-s phase" (i.e., low, semiconducting); space group P2 1 /c] to an electrically insulating (10) hexagonal symmetry high-chalcocite phase (7, 11) [hereafter called the "H-i phase" (i.e., high, insulating); space group P6 3 /mmc]. The coinciding changes in the bulk electrical conductivity and crystal structure present a possibility for exploring the relationship between electronic and structural phase transitions. Difficulties in the synthesis of stoichiometric Cu 2 S material and the lack of detailed theoretical treatments of both the crystal and the electronic structures of Cu 2 S have hindered the understanding of the phase transition (7, 11-13). Results and DiscussionWe have recently synthesized high-quality Cu 2 S nanoplates (Materials and Methods), which are on the order of 10-nm thick and 100 nm in lateral dimension ( Fig. 1 A and B)....

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Secondary electron emission studies

Cited by 168 publications

References 12 publications

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S

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Secondary electron emission studies

Cited by 168 publications

References 12 publications

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

Reversible structure manipulation by tuning carrier concentration in metastable Cu 2 S

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Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S