This experimental chamber has been entirely designed and developed at the Paul Scherrer Institute. It consists of a small-volume, high-pressure cell connected to two vertical tubes having a diameter of 3.0 cm. The total volume (cell+tubes) is around 150 cc. With the sample placed in the middle of the cell, a gas flow can be created by opening the gas line upstream and pumping the exhaust downstream. The sample can be precisely moved while measuring in the mbar range (precision +- 10 microns).
Both environmental chemistry/surface chemistry and heterogeneous catalysis experiments can be carried out. The cell can operate in static mode (pumped only from the aperture of the analyzer) or in flow configuration. The maximum pressure while measuring depends on the excitation energy used. With soft x-rays, photoemission and absorption spectra can be acquired up to 5 mbar. Sample treatments are possible up to 50 mbar. The pressure is measured by means of Baratron capacitance heads.
The small volume of the experimental cell and the flow tube configuration allow fast gas switching from one mixture to another (in the second timescale), while acquiring photoemission spectra in fast-scan mode (fixed or swept mode). We were recently introducing time-resolved measurements, and could get information about the evolution of real samples (powder catalyst) in specific reaction mixtures as a function of time in the second range. Time resolution is one of the next frontiers in in-situ XPS and will make possible to follow dynamic structural changes that typically occur in catalysts. It will also provide quantitative structure-performance relations previously not accessible.

The endstation is equipped with a ScientaOmicron R4000 HiPP-2 electron analyzer (https://scientaomicron.com/Downloads/Brochures/ESPEC/HIPP_2_SO_Flyer_05_2018.pdf) with three differential pumping stages.

5 * 10^-8 [mbar]

Crystal, Fiber, Powder

Crystal samples can be fixed to the sample holder by means of metallic clips.
Thin and homogeneous layers of powder samples can be drop cast (a spin coater is available at the beamline) on conductive and inert metal foils (e.g. Au, Ag). Such foils are then fixed to the sample holder by means of metallic clips.

X = 10 [mm], Y = 10 [mm], Z = 1 [mm]

Partial electron yield NEXAFS spectroscopy can be acquired tuning a kinetic energy window (in fixed or in swept mode) of the electron analyzer on an Auger line or on the tail of an Auger line. A software allows the automatic acquisition of the spectrum, thus controlling and acquiring both the beamline and the electron analyzer parameters.

Tie-resolved XPS studies are possible under transient conditions. Thanks to the flow configuration and to the small volume of the experimental cell, fast switches from a gas/gas mixture to another are possible while acquiring a photoemission peak (transient conditions experiments).

XPS can be acquired both in fixed (fixed kinetic energy window, acquisition time tunable with lowest frame rate corresponding to 40 ms) and in swept mode.

Multichannel Place (MCP) coupled to CCD camera

Yes

Electron