Implementation and operation of a fiber-coupled CMOS detector in a low energy electron Microscope.

The intrinsically weak signals in ultrafast electron microscopy experiments demand an improvement in the signal-to noise ratio of suitable electron detectors. We provide an experience report describing the installation and operation of a fiber-coupled CMOS based detector in a low energy electron microscope. We compare the detector performance to the traditional multi-channel-plate-based setup. The high dynamic range CMOS detector is capable of imaging spatially localized large intensity variations with low noise. The detector is blooming-free and overexposure appears uncritical. Overall, we find dramatic improvements in the imaging with the fiber-coupled CMOS detector compared to imaging with our previously used multi-channel-plate detector.

Systemic biomarkers currently implicated in the formation of abdominal wall hernia: A systematic review of the literature.

BACKGROUND: Surgery to the abdominal wall is ubiquitous worldwide and hernia treatment is challenging and expensive, posing a critical need to tailor treatment to individual patient risk-factors. In this systematic review, we consider specific systemic factors with potential as biomarkers of hernia formation. METHODS: A healthcare database-assisted search, following PRISMA guidelines, identified journal articles for inclusion and analysis. RESULTS: 14 biomarker studies were selected, comparing hernia patients and hernia-free controls, focusing on markers of extracellular matrix (ECM) remodelling and collagen turnover. Matrix metalloproteinase-2 was increased in patients with inguinal hernia. Markers of type IV collagen synthesis were increased in patients with abdominal wall hernia; while markers of fibrillar collagen synthesis were reduced. Additional other ECM signalling proteins differ significantly within published studies. CONCLUSION: We identify a lack of high-quality evidence of systemic biomarkers in tailoring treatment strategies relative to patient-specific risks, but recognise the potential held within biomarker-based diagnostic studies to improve management of hernia pathogeneses.

A new aberration-corrected, energy-filtered LEEM/PEEM instrument II. Operation and results.

In Part I we described a new design for an aberration-corrected Low Energy Electron Microscope (LEEM) and Photo Electron Emission Microscope (PEEM) equipped with an in-line electron energy filter. The chromatic and spherical aberrations of the objective lens are corrected with an electrostatic electron mirror that provides independent control of the chromatic and spherical aberration coefficients Cc and C3, as well as the mirror focal length. In this Part II we discuss details of microscope operation, how the microscope is set up in a systematic fashion, and we present typical results.

A new aberration-corrected, energy-filtered LEEM/PEEM instrument. I. Principles and design.

We describe a new design for an aberration-corrected low energy electron microscope (LEEM) and photo electron emission microscope (PEEM), equipped with an in-line electron energy filter. The chromatic and spherical aberrations of the objective lens are corrected with an electrostatic electron mirror that provides independent control over the chromatic and spherical aberration coefficients C(c) and C(3), as well as the mirror focal length, to match and correct the aberrations of the objective lens. For LEEM (PEEM) the theoretical resolution is calculated to be approximately 1.5 nm (approximately 4 nm). Unlike previous designs, this instrument makes use of two magnetic prism arrays to guide the electron beam from the sample to the electron mirror, removing chromatic dispersion in front of the mirror by symmetry. The aberration correction optics was retrofitted to an uncorrected instrument with a base resolution of 4.1 nm in LEEM. Initial results in LEEM show an improvement in resolution to approximately 2 nm.

A simple energy filter for low energy electron microscopy/photoelectron emission microscopy instruments.

Addition of an electron energy filter to low energy electron microscopy (LEEM) and photoelectron emission microscopy (PEEM) instruments greatly improves their analytical capabilities. However, such filters tend to be quite complex, both electron optically and mechanically. Here we describe a simple energy filter for the existing IBM LEEM/PEEM instrument, which is realized by adding a single scanning aperture slit to the objective transfer optics, without any further modifications to the microscope. This energy filter displays a very high energy resolution ΔE/E = 2 × 10(-5), and a non-isochromaticity of ∼0.5 eV/10 µm. The setup is capable of recording selected area electron energy spectra and angular distributions at 0.15 eV energy resolution, as well as energy filtered images with a 1.5 eV energy pass band at an estimated spatial resolution of ∼10 nm. We demonstrate the use of this energy filter in imaging and spectroscopy of surfaces using a laboratory-based He I (21.2 eV) light source, as well as imaging of Ag nanowires on Si(001) using the 4 eV energy loss Ag plasmon.