A pEek on the lab

Weizmann Institute of Science, Israel, is one of the world’s leading multidisciplinary basic research institutions in the natural and exact sciences. Weizmann has strong experience in molecular chemistry and material science research with an accent on energy storage and sustainability.

  The Electron Spectroscopy Unit is part of the Surface Analysis facility that provides surface analytical data by means of high-energy excitation sources and an analyzer of the kinetic energies of electrons emitted from the studied surface. The instrumentation consists of an ultrahigh vacuum (UHV) multifaceted system, with X-ray Photoelectron Spectroscopy (XPS) as the main technique, allowing a variety of operational modes and access to a broad range of chemical and electronic characteristics.

XPS is a popular quantitative surface analysis technique that can easily resolve any element of the periodic table except for hydrogen. It provides unique analytic capabilities, mainly because of its reliable quantification of elemental concentrations (a ‘counter’ of atoms) and remarkable resolving power of elemental oxidation states.  In many cases, detailed information, down to atomic-scale sensitivity, can be derived about the vertical ordering of atoms within the top 10-15 nm of the inspected surface.

The AXIS Ultra DLD spectrometer (Kratos Analytical) combines state-of-the-art XPS performance with unrivalled automation and ease of use. This instrument excels in both spectroscopy and imaging modes and has the flexibility to incorporate complementary surface analytical techniques.

Our standard XPS analyses are based on a monochromatic Al kα X-ray source and a magnetic lens incorporated within the detection setup. Thus, the spectral resolution and signal intensities are optimized, allowing fast and powerful surface-composition quantifications. The detection can be further performed in a novel mode of parallel imaging, which provides energy-filtered lateral mapping of elemental distributions at 3 µm resolution.

Cryogenic XPS is operated down to ~100 K, which opens interesting possibilities for studies of the temperature dependence of various properties and, even more important, applying XPS to samples with relatively high vapor pressure and even specific liquids. 

UPS technique dedicated to studies at improved energy resolution of the valence-electron energy bands and the secondary electron emission (SEE) spectrum. Our setup uses a He lamp at photon energies of 21.2 eV (He I) and 40.8 ev (He II). UPS can also be used to derive the sample work-function.