LiXEdrom: Innovative measuring chamber for X-ray study of liquid jets
Close-up of the liquid-jet.
Schematic drawing of the LiXEdrom setup for X-ray
absorption and X-ray emission
spectroscopy on the liquid-jet
Until now, the only way to study liquids by soft X-ray emission spectroscopy (XES) has been through a membrane window. Now, researchers of Helmholtz-Zentrum Berlin have carried out an XES study of a free micro-liquid jet on the synchrotron.
X-rays are the medium of choice for many scientific studies. When you shine them on a sample, they literally shed light on the material’s structure, providing loads of information about it. Unfortunately, this mostly applies to solids only, since the sample has to be in a vacuum for the entire time it is being irradiated with soft X-rays. For liquids, that means you have to remove all the water. In the case of biological samples such as proteins, however, this destroys their natural environment. The solution to this problems has always been to measure liquids through membranes. These membranes keep the evacuated side separate from the non-evacuated side. The trouble is, one can never really be sure whether or not membrane effects are distorting the measurement results.
At Helmholtz-Zentrum Berlin (HZB), Emad Aziz, head of a junior research group, has shown that liquids can be investigated by X-ray emission spectroscopy without using membranes after all. At the synchrotron source BESSY II, the group has built a special setup – the LiXEdrom. It is unique in that the liquid is shot as a jet through the X-ray beam. The jet from the nozzle becomes so thin and, at 80 metres per second, so fast that the vacuum can be maintained without the need of a membrane.
“On our LiXEdrom, we create a vacuum in the liquid chamber of up to 10-6 millibar, and can now perform both absorption and emission measurements, giving us even more precise information about the structure of a material,” says Emad Aziz. It also allows a clear “view” of elements that possess absorption and emission energies similar to the energies of the membrane materials, and would therefore overlap with the membrane in the spectrum when measured. This concerns above all carbon and nitrogen – precisely those elements of interest in biological samples.
In their first measurements, published in Chemical Physics (DOI: 10.1016/JChemPhys.2010.08.023) and selected for the cover, the group demonstrated they can achieve energy resolutions on their LiXEdrom comparable to those of the latest high resolution XES spectrometers. For water, they have proven that results obtained from an earlier setup were not overlapped by disturbing membrane effects. They have also studied the electronic structure of nickel ions, unhampered by a risk of deposits on a membrane wall distorting the results. For many applications such as protein studies, this is a significant step towards obtaining reliable structural information.
Original paper in Chem. Phys., DOI 10.1016/JChemPhys.2010.08.023
„High Resolution X-ray Emission Spectroscopy of Water and Aqueous Ions Using the Micro-Jet Technique”, K.M. Lange et al.
- Porous Radical Organic framework improves lithium-sulphur batteriesA team led by Prof. Yan Lu, HZB, and Prof. Arne Thomas, Technical University of Berlin, has developed a material that enhances the capacity and stability of lithium-sulphur batteries. The material is based on polymers that form a framework with open pores (known as radical-cationic covalent organic frameworks or COFs). Catalytically accelerated reactions take place in these pores, firmly trapping polysulphides, which would shorten the battery life. Some of the experimental analyses were conducted at the BAMline at BESSY II.
- Metallic nanocatalysts: what really happens during catalysisUsing a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY's NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.
- Key technology for a future without fossil fuelsIn June and July 2025, catalyst researcher Nico Fischer spent some time at HZB. It was his sabbatical, he was relieved of his duties as Director of the Catalysis Institute in Cape Town for several months and was able to focus on research only. His institute is collaborating with HZB on two projects that aim to develop environmentally friendly alternatives using innovative catalyst technologies. The questions were asked by Antonia Rötger, HZB.