The continuing development of low-energy electron microscopy for characterizing surfaces

Abstract

Instrumental aspects of low-energy electron microscopy are reviewed with a view toward the future evolution of this reemergent technology. Both elastically scattered and inelastically excited electrons in the 0–1000-eV range may be used to form direct rather than scanned images of surfaces in the 3–10-nm resolution range. Different instrumental setups may be used to form images that selectively contain information about the topography, crystalline structure, chemical composition, or magnetic orientation of the first few monolayers. Frequently, parallel imaging allows observation of dynamic processes occurring during observation. Key electron optical elements and their systemic relationships are described in the context of a still hypothetical generalized instrument that would allow complementary exploitation of many contrast modes. Image quality issues such as resolution, sensitivity, statistics, and contrast selectivity are considered with a view toward their optimization, in many cases by drawing ideas and technologies from other fields of microscopy.

Xpeem With Energy-Filtering: Advantages and First Results From the Smart Project

“…The microscope is a UHV instrument with a base pressure of 10 −10 mbar in the image column, OMEGA filter, and in the measurement chamber. The design of the latter and of the sample manipulator is similar to that developed in Clausthal, 19,20 which enables in situ evaporation, heating up to 2300 K and cooling down to 200 K, and gas treatment up to about 10 −6 mbar even during observation, when the high voltage of 15 kV is applied to the sample.…”

Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

“…Photoemission electron microscopy (PEEM) is a well-established technique in the surface science community; it relies on photoemission of electrons from compositionally or structurally complex surfaces and images their spatial distributions with electron optics. ,− PEEM imaging has several unique advantages over other microscopic techniques, as we will explain. Because photoemission techniques are sensitive to the chemical composition of a surface, PEEM is a particularly selective technique for investigating surface chemical phenomena .…”

Tungstate formation in a model scandate thermionic cathode

“…[11][12][13][14][15] The sample is exposed to air before it is introduced into the microscope. [11][12][13][14][15] The sample is exposed to air before it is introduced into the microscope.…”