Experimental Station

The experimental station at PIRX beamline is a UHV system outfitted with two-chambers: a  spectroscopy measurement chamber equipped with LHe cryostat and electromagnet and preparation chamber for in-situ experiments. The two chambers  together with a load lock are connected by a sample transfer system that operates manually under ultra-high vacuum.

Figure 6. A model of the end station, which consists of two chambers (spectroscopy and preparation) and a load lock.

Sample requirements

• UHV compatible;
• Samples (powder and bulk) fitting a standard flag-style (an Omicron type plate) sample holder;
• Should not charge under X-ray illumination.

Measurement conditions

• Total electron yield (TEY) detection mode, giving a sampling depth of several nm;
• Total (TFY) and partial (PFY) fluorescence mode using an SDD fluorescent detector, giving a sampling depth of several hundreds of nm; 
• Transmission mode using an AXUV photodiode. It requires a special holder and sample preparation, which makes it possible for experienced groups after prior consultation with scientists working on the beamline;
• The partial electron yield (PEY) detection mode, giving a sampling depth of a few nm for samples with low electrical conductivity using an electron multiplier (channeltron). Detection mode is available after prior consultation with the beamline scientists;
• Available external magnetic field of 0-140 mT parallel to the photon beam;
• Sample environment from UHV to high vacuum. Special conditions like He exchange gas (maximum 10 mbar) can also be available but rarely and it depends on the actual beamline status. Due to that, these conditions are not offered as standard sample environment. The need for this must be discussed directly with beamline scientists well in advance;
• Available sample temperature during measurements:  20-670 K for experiments in high  and ultra high vacuum conditions. Limited heating and cooling capabilities are possible for exchange gas environment. In the preparation chamber: 150 K – 2000 K.

Sample holder

The drawing below shows the Omicron-type plate (flag style) used as a sample holder. The marked space determines the available area of sample holder for sample mounting. Minimum size of the sample is limited by the beam spot size at end station, which is 250 µm x 40 µm.
Please remember that for temperature dependent experiment (cooling or heating) the sample installation using clamps, wires or screws is required.

Figure 7. The drawing of omicron-type plate/ flag style holder (dimensions are in mm) with marked available area for sample. 

Figure 8. The examples of sample mounting on the holder. (a,b) The powder samples installed using carbon tape, (c,d) the single crystal or specimen deposited on substrates installed using carbon tape, (e,f) the single crystal installed using tungsten wires, (g,h) the sample installed using clamps or screws.

Measurement geometry

The magnetic field up to 0.14 T along the beam direction can be applied. The sample can be rotated about the vertical axis +/- 100 degree in the centre of the electromagnet.

Figure 9. The measurement geometry relative to the photon beam axis and the electromagnet, (left) diagram (right) photo of the sample holder placed into the manipulator in relation to the electromagnet's yokes.

Preparation chamber

• 4 axis manipulator allowing colling to 150 K and heating to 1200 K (short flash to 2200 K);
• LEED/AES Spectrometer;
• Metal vapour sources (Fe, Co, Au, Cr, Ni) controlled with a quartz crystal balance;
• RGA
• Broad beam ion gun (Ar);
• Oxygen dosing system.