Surface sensitivity in scanning transmission x-ray microspectroscopy using secondary electron detection

Abstract

The successful integration of electron detection into an existing scanning transmission x-ray microspectroscope (STXM) at the Swiss Light Source is demonstrated. In conventional x-ray detection using a photomultiplier, STXM offers mainly bulk sensitivity combined with high lateral resolution. However, by implementation of a channeltron electron multiplier, the surface sensitivity can be established by the detection of secondary electrons emitted from the sample upon resonant excitation. We describe the experimental setup and discuss several relevant aspects, in particular the schemes to correct for self-absorption in the specimen due to back illumination in case of thicker films.

Imaging the domain structure of organic semiconductor films

“…The feasibility of combined surface and bulk imaging with STXM has been demonstrated by using a channeltron detector mounted after the sample alongside the photon detector. 43,44 In this way, the surface domain structure of polycrystalline F8BT has also been measured and shown to exhibit a similar morphology to that of the bulk. 37 Photoemission electron microscopy (PEEM) with polarized soft X-rays in principle should also allow direct imaging of domain structure in a more convenient imaging geometry.…”

NanoXAS—The in situ Combination of Scanning Transmission X-ray and Scanning Probe Microscopy

“…Total electron yield measurements can be realized by measuring the drain current or by direct detection of the secondary electrons using a channeltron. In the latter case, surface sensitivity in STXM analysis can greatly be enhanced [4,6]. SPM also allows us to measure local conductance maps or Kelvin probe force microscopy.…”

“…The chemical contrast in STXM can be directly correlated to the morphological/topographical features of surfacesensitive SPM. This is important since the 2D projection in STXM cannot directly be separated into surface or bulktype information [4]. Conversely, SPM offers only limited chemical contrast.…”

Coherent X-ray Imaging: Bridging the Gap between Atomic and Micro-scale Investigations

“…[56,57] Electron detection has been used to map surface composition. [50,58] Furthermore, magnetic domains can be imaged based on X-ray magnetic circular dichroism and their dynamics followed in pump-probe experiments. [48,59] Phase contrast is also possible, although absorption contrast is often more advantageous in the soft X-ray region of the spectrum where STXM experiments are commonly conducted.…”