Spot profile analysis and lifetime mapping in ultrafast electron diffraction: Lattice excitation of self-organized Ge nanostructures on Si(001)

Frigge, T.; Hafke, B.; Tinnemann, V; Witte, Thomas; Hoegen, M. Horn‐von

doi:10.1063/1.4922023

Cited by 8 publications

(5 citation statements)

References 51 publications

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“…The pattern was recorded at a sample temperature of 25 K, with an electron energy of 20 keV and a grazing angle of incidence of 3.2. We will show that several specific diffraction features allow a clear identification and separation of spot intensities from hut and dome clusters [28]. In particular, this includes hut cluster spots and spots composed of contributions from both hut and dome clusters.…”

Section: Resultsmentioning

confidence: 88%

Nanoscale thermal transport in self-organized epitaxial Ge nanostructures on Si(001)

Frigge¹,

Hafke²,

Tinnemann³

et al. 2015

Semicond. Sci. Technol.

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The thermal transport properties of self-organized Ge nanostructures on Si were studied by means of ultrafast surface sensitive time-resolved electron diffraction. The thermal boundary resistance was determined from the temperature response of the Ge nanostructures upon impulsive heating by fs-laser pulses. The transient temperature was determined through the Debye-Waller effect. Epitaxial growth of Ge hut and dome clusters was achieved by in-situ deposition of 8 monolayers of Ge on Si(001) at 550 °C under ultra-high vacuum conditions. Time-resolved spot profile analysis of different orders of diffraction spots was used to distinguish between the thermal response of hut and dome clusters. Dome clusters of 6 nm height and 50 nm width cool with a time constant of 150 ps t = which agrees well with numerical simulations calculated in the framework of the diffuse mismatch model. The much smaller hut clusters with a height of 2.3 nm and width of 23 nm exhibit a cooling time of 55 ps t = , which is a factor of 2 slower than predicted by theory.

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Section: Resultsmentioning

confidence: 88%

Nanoscale thermal transport in self-organized epitaxial Ge nanostructures on Si(001)

Frigge¹,

Hafke²,

Tinnemann³

et al. 2015

Semicond. Sci. Technol.

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“…Finally, heterogeneous chemistry, relevant to applications in catalysis, is an extremely important area for exploration. There has been great progress in developing femtosecond reflected high-energy electron diffraction (RHEED) for surface studies and LEED approaches using nanotips for the shortest propagation distances possible to maintain time resolution. − These studies have revealed very interesting cooperative surface effects. In terms of surface chemistry, the main challenge is the irreversible nature of surface reaction dynamics.…”

Section: Summary and Future Outlookmentioning

confidence: 99%

Capturing Chemistry in Action with Electrons: Realization of Atomically Resolved Reaction Dynamics

2017

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One of the grand challenges in chemistry has been to directly observe atomic motions during chemical processes. The depiction of the nuclear configurations in space-time to understand barrier crossing events has served as a unifying intellectual theme connecting the different disciplines of chemistry. This challenge has been cast as an imaging problem in which the technical issues reduce to achieving not only sufficient simultaneous space-time resolution but also brightness for sufficient image contrast to capture the atomic motions. This objective has been met with electrons as the imaging source. The review chronicles the first use of electron structural probes to study reactive intermediates, to the development of high bunch charge electron pulses with sufficient combined spatial-temporal resolution and intensity to literally light up atomic motions, as well as the means to characterize the electron pulses in terms of temporal brightness and image reconstruction. The use of femtosecond Rydberg spectroscopy as a novel means to use internal electron scattering within the molecular reference frame to obtain similar information on reaction dynamics is also discussed. The focus is on atomically resolved chemical reaction dynamics with pertinent references to work in other areas and forms of spectroscopy that provide additional information. Effectively, we can now directly observe the far-from-equilibrium atomic motions involved in barrier crossing and categorize chemistry in terms of a power spectrum of a few dominant reaction modes. It is this reduction in dimensionality that makes chemical reaction mechanisms transferrable to seemingly arbitrarily complex (large N) systems, up to molecules as large as biological macromolecules (N > 1000 atoms). We now have a new way to reformulate reaction mechanisms using an experimentally determined dynamic mode basis that in combination with recent theoretical advances has the potential to lead to a new conceptual basis for chemistry that forms a natural link between structure and dynamics.

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“…Turning disadvantage into opportunities, ultrafast electrons have been used to monitor the transient electric field distribution of various materials beyond TR-RHEED application. [8,83] Attaching molecules, nanoparticles, [84] or low dimension structures on a surface [85] create new opportunities to study catalysis, functional materials, and sample-substrate correlations by UED, yet this field is still waiting for further exploration.…”

Section: Surface Science and Beyondmentioning

confidence: 99%

Ultrafast electron diffraction

Wang¹,

Li²

2018

Chinese Phys. B

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Ultrafast electron diffraction (UED) technique has proven to be an innovative tool for providing new insights in lattice dynamics with unprecedented temporal and spatial sensitivities. In this article, we give a brief introduction of this technique using the proposed UED station in the Synergetic Extreme Condition User Facility (SECUF) as a prototype. We briefly discussed UED's functionality, working principle, design consideration, and main components. We also briefly reviewed several pioneer works with UED to study structure-function correlations in several research areas. With these efforts, we endeavor to raise the awareness of this tool among those researchers, who may not yet have realized the emerging opportunities offered by this technique.

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Spot profile analysis and lifetime mapping in ultrafast electron diffraction: Lattice excitation of self-organized Ge nanostructures on Si(001)

Cited by 8 publications

References 51 publications

Nanoscale thermal transport in self-organized epitaxial Ge nanostructures on Si(001)

Nanoscale thermal transport in self-organized epitaxial Ge nanostructures on Si(001)

Capturing Chemistry in Action with Electrons: Realization of Atomically Resolved Reaction Dynamics

Ultrafast electron diffraction

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