Imaging XPS—a new technique. 2—Experimental verification

Abstract

The XPS image is obtained by the dissection of the surface area of interest into a series of adjacent narrow strips. The width of the entrance slit system of the energy analyzer gives the strip width and a translational movement of the specimen makes it possible to investigate the total number of strips step by step. By means of the double focusing properties of the spherical analyzer the energy spectrum from each point (spot) of the strip area under observation is available on the detector focal plane. Specific photoelectron lines are selected by a suitable choice of the sphere voltages. A position sensitive electron detector together with a computer is used to collect and store these spectra simultaneously in the course of one measurement. The net count rate is evaluated afterwards. Each spot of the strip is represented by its corresponding value of the net count rate and the series of values is stored in a computer memory. At the end of collection of all the strip information the image is put together strip by strip. To date a resolution of 0.3 mm has been realised and the time of data collection for an area of 10 X 10 mm2 is about one hour. The corresponding time of measurement with our imaging method is just a few minutes as one needs only the elemental distribution of an element along a single line as in an electron micronalyzer with a line scan.

In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

“…67 We also employed XPS spectromicroscopy to analyze the underlying growth mechanism of the SEI layer, which can provide realistic views of concentration gradients in the spatial domain. 68,69 Figure 4 shows a two-dimensional chemical imaging performed at the same spot on the Li-anode after the first charge/discharge process (see the Supporting Information). The interfacial region (800 × 800 μm) is scanned at 685 eV (F 1s; Li−F species) and 163.3 eV (S 2p; S B 0 ) binding energies to monitor the TFSI anion and polysulfide gradient with a spatial resolution of about 5 μm.…”