Complementary LEEM and eV-TEM for imaging and spectroscopy

Neu, Peter S.; Geelen, Daniël; Thete, Aniket; Tromp, R. M.; Molen, Sense Jan van der

doi:10.1016/j.ultramic.2020.113199

Cited by 4 publications

(5 citation statements)

References 31 publications

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“…To summarize, we have studied electron transmission through MoS 2 and have directly obtained the mean free path as a function of electron energy, λ(E ), in the 0-55 eV energy range. This demonstrates that we can extend the methodology we previously applied to graphene [5,6] to the more complex TMDs. In contrast to graphene, the maximum transmissivity is found in a large window at 10−25 eV, rather than at energies below 5 eV.…”

Section: Discussionmentioning

confidence: 61%

“…1(c)]. For eV-TEM, we use a second electron source behind the sample to form transmission images of low-energy electrons transmitted without scattering and/or energy loss [5,6]. As both methods are available in the same instrument, we can image the same sample area in both reflectivity and transmissivity, so that they can be readily and directly compared.…”

Section: Methodsmentioning

confidence: 99%

“…For graphene, the most popular van der Waals material, the low-energy MFP has been reported to be in the order of a few layers based on electronenergy-loss spectroscopy (EELS) [2], measurements of the secondary electron spectrum generated in a SEM [3], and by photoemission [4]. Recently, our group has demonstrated a more direct method to extract the MFP from a combination of low-energy electron microscopy (LEEM) and electron-volt transmission electron microscopy (eV-TEM) [5,6]. In contrast to the "universal" curve, our study on few-layer graphene showed multiple maxima and minima depending on layer count.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electron transmission and mean free path in molybdenum disulfide at electron-volt energies

Neu

Šiškins²,

Krasovskii³

et al. 2023

Phys. Rev. B

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In van der Waals (vdW) materials, the electron mean free path (MFP) is largely influenced by the discrete states in the unoccupied band structure. So far, the influence of these states has only been measured in graphene, while all measurements on other vdW materials lack energy resolution. Here, we present reflection and transmission spectra of freestanding, few-layered molybdenum disulfide (MoS 2 ) samples in the 0-55 eV electron range. Our measurements reveal states of enhanced electron transmissivity above the vacuum level, that correspond to the (unoccupied) density of states. We also show a full quantum-mechanical calculation that confirms a good understanding of the elastic scattering in MoS 2 . A model is developed to extract the inelastic MFP spectrum, which is a measure of the inelastic scattering cross section. As MoS 2 is a complicated system of different atomic planes, we expect that our methods generalize well to other van der Waals materials and heterostacks thereof.

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Section: Discussionmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron transmission and mean free path in molybdenum disulfide at electron-volt energies

Neu

Šiškins²,

Krasovskii³

et al. 2023

Phys. Rev. B

Self Cite

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“… 17 Combining a second electron source into a low-energy electron microscope (LEEM) setup allowed for developing TEM at low energy for imaging and spectroscopy in transmission and reflection modes at nanometer (nm) resolution. 18 This technique prevents high-energy electrons from damaging fragile biological samples and enables nondestructive imaging of biological samples at nanometer resolution. However, Rikkert et al found that operator subjectivity significantly affected the results, in addition to the different working protocols.…”

Section: Characterization Techniques For Sevmentioning

confidence: 99%

Application of Single Extracellular Vesicle Analysis Techniques

Zhu,

Wu,

et al. 2023

IJN

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Extracellular vesicles (EVs) are lipid containers that are actively released by cells and contain complex molecular cargoes. These cargoes include abundant material such as genomes and proteins from cells of origin. They are involved in intercellular communication and various pathological processes, showing excellent potential for diagnosing and treating diseases. Given the significant heterogeneity of EVs in complex physiopathological processes, unveiling their composition is essential to understanding their function. Bulk detection methods have been previously used to analyze EVs, but they often mask their heterogeneity, leading to the loss of valuable information. To overcome this limitation, single extracellular vesicle (SEV) analysis techniques have been developed and advanced. These techniques allow for analyzing EVs’ physical information and biometric molecules at the SEV level. This paper reviews recent advances in SEV detection methods and summarizes some clinical applications for SEV detection strategies.

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“…In addition to the techniques discussed here, other techniques, such as aloof beam electron energy-loss spectroscopy (EELS) (Krivanek et al, 2014;Egerton, 2015;Rez et al, 2016), structured illumination with compressed sensing Li et al, 2018;Leary & Midgley, 2019), and adaptive optics with pixelated phase plates (Verbeeck et al, 2018), could also have potential applications in imaging or characterization of biological specimens. TEM at low voltage reduces the radiation damage to the sample (Kaiser et al, 2011;Egerton, 2019), and ultra-low-energy electron microscopy (LEEM) and eV-TEM at 0-30 eV have much less plasmonic and excitonic interactions, which results in almost no energy being deposited in the specimen (Geelen et al, 2015;Neu et al, 2021). TEM at such low acceleration voltage can, however, only achieve spatial resolution at a few nanometre range which will not allow for de novo structure determination.…”

Section: Figurementioning

confidence: 99%

Single-particle cryo-EM: alternative schemes to improve dose efficiency

Zhang¹,

Lu²,

Rotunno³

et al. 2021

J Synchrotron Radiat

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Imaging of biomolecules by ionizing radiation, such as electrons, causes radiation damage which introduces structural and compositional changes of the specimen. The total number of high-energy electrons per surface area that can be used for imaging in cryogenic electron microscopy (cryo-EM) is severely restricted due to radiation damage, resulting in low signal-to-noise ratios (SNR). High resolution details are dampened by the transfer function of the microscope and detector, and are the first to be lost as radiation damage alters the individual molecules which are presumed to be identical during averaging. As a consequence, radiation damage puts a limit on the particle size and sample heterogeneity with which electron microscopy (EM) can deal. Since a transmission EM (TEM) image is formed from the scattering process of the electron by the specimen interaction potential, radiation damage is inevitable. However, we can aim to maximize the information transfer for a given dose and increase the SNR by finding alternatives to the conventional phase-contrast cryo-EM techniques. Here some alternative transmission electron microscopy techniques are reviewed, including phase plate, multi-pass transmission electron microscopy, off-axis holography, ptychography and a quantum sorter. Their prospects for providing more or complementary structural information within the limited lifetime of the sample are discussed.

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Complementary LEEM and eV-TEM for imaging and spectroscopy

Cited by 4 publications

References 31 publications

Electron transmission and mean free path in molybdenum disulfide at electron-volt energies

Electron transmission and mean free path in molybdenum disulfide at electron-volt energies

Application of Single Extracellular Vesicle Analysis Techniques

Single-particle cryo-EM: alternative schemes to improve dose efficiency

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