High Pressure CELL

The high pressure cell (HPCELL) setup consists of a specially designed high vacuum compatible cell mounted on a standard sample holder as shown in Fig. XX. The sample is encapsulated within the NAP-Cell and located 500 μm far away from the surface of the inner body of the cell. The sample position is also the intersection point of the trajectories of two 500 μm diameter size pinholes, one to let the incoming X-rays entering the cell and the second one pointing the HEA to allow the generated photoelectrons to properly enter the electron analyser.

The focused X-ray beam scans the sample through the pinhole, which is orthogonal to the surface of samples. The generated photoelectrons come throughout the second pinhole, which has a conical shape and spans along to electron acceptance direction and cone of HEA to guarantee a high photoelectron transmission. With this design, we got 400 μm diameter aerial circle of view on the sample. A pumping/dosing line is connected to the cell to control environment of samples, and it is flexible enough for the piezoelectric motors to scan samples in imaging mode.

The pressure inside the cell can be raised near to 0.2 mbar range while the equilibrium pressure in the main chamber can be kept around              1 × 10-5 mbar, which is the safety limit for the SPEM system in normal operation mode without necessity of any differential pumping system. Samples can be mounted insulated from the body of the cell, having two independent electrical contacts for potential and current application, so even in operando type experiments are feasible with this design.

A second version of the HPCELL is also available. In this version the two pinholes design for X-ray and Electrons is substituted with a single smaller pin hole of 150-200 um diameter for both photons and electrons. This single pin-hole allows to rise the pressure up to 1mbar, but with a smaller field of view and without the possibility to electrically bias the sample.
For both configuration the sample dimensions are up to 10 x 10 x 2 mm and a ceramic heater is located behind the sample for controlling the temperature of samples in the range 300–1073 K.
- H. Sezen et al, Surface and Interface Analysis (2017) - doi: 10.1002/sia.6276

Last Updated on Monday, 29 October 2018 12:19