Double aberration correction in a low-energy electron microscope

Schmidt, Thomas; Marchetto, Helder; Lévesque, Pierre L.; Groh, Ulli; Maier, Florian; Preikszas, D.; Hartel, Peter; Spehr, R.; Lilienkamp, G.; Engel, W.; Fink, R.; Bauer, E.; Rose, H.; Umbach, E.; Freund, Hans‐Joachim

doi:10.1016/j.ultramic.2010.07.007

Cited by 81 publications

(66 citation statements)

References 36 publications

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“…In the present approach, i.e. using a multimethod spectro-microscope, such as the SMART, [6][7][8]42,43 we could limit this risk since a combination of methods could be applied quasi simultaneously to the same sample, even to the same spot on the sample, in a single instrument. The methods used in the present work, i.e.…”

Section: Multi-methods Approach For Comprehensive Characterizationmentioning

confidence: 99%

“…Experimentally demonstrated is a (conservatively measured) lateral resolution of 2.6 nm in LEEM and 18 nm in energy-filtered XPEEM, 42,43 respectively, and an increase in transmission by a factor of 6. 43 The instrument is installed at a soft X-ray, high flux-density undulator beam line at BESSY II with tunable photon energy range between 100 and 1000 eV and high photon energy resolution (o0.1 eV).…”

Section: Instrumental Set-upmentioning

confidence: 97%

“…SMART is a new type of spectro-microscope that combines a ''standard'' LEEM/PEEM instrument with aberration corrections (both, chromatic and spherical aberrations) [40][41][42][43] and with energy resolution using an imaging energy filter. Theoretically, Fig.…”

Section: Instrumental Set-upmentioning

confidence: 99%

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Direct observation of epitaxial organic film growth: temperature-dependent growth mechanisms and metastability

Marchetto

Schmidt

Groh

et al. 2015

Phys. Chem. Chem. Phys.

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The growth of the first ten layers of organic thin films on a smooth metallic substrate has been investigated in real-time using the model system PTCDA on Ag(111). The complex behaviour is comprehensively studied by electron microscopy, spectroscopy and diffraction in a combined PEEM/LEEM instrument revealing several new phenomena and yielding a consistent picture of this layer growth. PTCDA grows above room temperature in a Stranski-Krastanov mode, forming three-dimensional islands on a stable bi-layer, in competition with metastable 3rd and 4th layers. Around room temperature this growth mode changes into a quasi layer-by-layer growth, while at temperatures below about 250 K a Vollmer-Weber-like behaviour is observed. By means of laterally resolved soft X-ray absorption spectroscopy the orientation of all adsorbed molecules is found to be homogeneously flat lying on the surface, even during the growth process. The films grow epitaxially, showing long-range order with rotational domains. For the monolayer these domains could be directly analysed, showing an average size of several micrometers extending over substrate steps.

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Section: Multi-methods Approach For Comprehensive Characterizationmentioning

confidence: 99%

Section: Instrumental Set-upmentioning

confidence: 97%

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Direct observation of epitaxial organic film growth: temperature-dependent growth mechanisms and metastability

Marchetto

Schmidt

Groh

et al. 2015

Phys. Chem. Chem. Phys.

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“…The main components of a LEEM instrument, as shown in the scheme in Fig. 2, are comparable to those in a PEEM instrument, with the exception of a beam splitting device (BS) with the attached electron gun and an optional electrostatic mirror unit (MO) that enables the correction of spherical and chromatic aberrations and therefore improves the lateral resolution and transmission [19,20]. In contrast to PEEM, which is a chemical sensitive technique, especially when using X-rays for excitation, LEEM is mainly a structural sensitive method.…”

Section: Photoemission Electron Microscopy (Peem) and Low Energy Elecmentioning

confidence: 99%

“…The degree of beam damage depends obviously on the chemical nature of the oxide, but is certainly an important issue that needs to be taken into account when performing in situ and in operando experiments, where the presence of gases (reactants) can trigger sample degradation, or when long acquisition times are required. In this regard, the successful correction of both, chromatic and spherical aberrations, in modern LEEM instruments have allowed the use of less demanding conditions to obtain images in terms of electron dosing on the samples and faster acquisition time [19,63,64]. The advantage of double aberration correction can be reflected on two different aspects.…”

Section: Future Perspectivesmentioning

confidence: 99%

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Prieto

Schmidt

2017

Catal Lett

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Catalysis is a hot topic in research with the focus on finding catalysts that show better activity or selectivity on processes on technological or industrial interest. The use of model systems of applicable materials has proven to be a successful approach in the last decades to obtain information on the fundamental properties of these materials, leading eventually to a better understanding how real catalysts work. This knowledge is extremely important in the sense that it allows an optimization of the catalyst composition, thus leading to a rational design of new materials. For these fundamental studies, a variety of probing techniques such as X-ray photo-electron spectroscopy, scanning tunnel microscopy, and temperature programmed desorption have been applied. In this article, we discuss how low energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) can contribute to the fundamental understanding of relevant surface processes taking place on model catalysts. Also, the capability of these techniques on addressing open questions in catalysis is discussed

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Low‐Energy Electron Microscopy

Bauer¹

1996

Handbook of Microscopy

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Double aberration correction in a low-energy electron microscope

Cited by 81 publications

References 36 publications

Direct observation of epitaxial organic film growth: temperature-dependent growth mechanisms and metastability

Direct observation of epitaxial organic film growth: temperature-dependent growth mechanisms and metastability

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Low‐Energy Electron Microscopy

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