Down to the Smallest Detail

Dr Elena Longo is working at the Beamline. Photo: Hereon/ Christian Schmid

The most brilliant storage ring X-ray source in the world is located at DESY, the Petra III. The storage ring with a circumference of 2304 metres has 24 beamlines. One is the imaging beamline P05, which belongs to Hereon and is supervised by its researchers.

The P05 has two measurement stations with fixed research groups: micro-tomography and nano-tomography. In recent years, both groups have carried out their own research and have assisted external user groups with their projects, as no one knows the beamlines as well as the IBL team themselves. This is the reason users come from all over the world to have their samples X-rayed.

Non-destructive X-rays

Keeping an eye on the samples: beamline scientist Dr Fabian Wilde has been working in X-ray imaging with synchrotron radiation since 2010. Photo: Hereon/ Christian Schmid

What is special here is that the scientists can take a glimpse inside the different materials without destroying them—whether they are metal or biologic samples. The IBL was created especially for in situ measurements and has been constructed with high flexibility to serve a wide variety of research fields: from materials science to medicine and biology to palaeontology. Only those who know the material structure down to the nanometre scale can begin to understand how they function or from where certain properties stem.

Dr Jörg Hammel has been supervising the most widely varying user groups and experiments as beamline scientist at the Hereon since 2014. Photo: Hereon/ Christian Schmid

The aim of the researchers is to visualize the largest possible area of any sample, as quickly as possible and in high resolution with the best possible contrast as a three-dimensional image on the computer. From a purely technical point of view, not all criteria could be fulfilled at the same time. With the new detector systems in micro- and nano-tomography, the Hereon scientists have taken a huge step closer to the ideal result though. Along with the constant new developments on the market for mobile phone cameras, the detectors that can be used in science have also become increasingly better.

Micro Station

Photo: Hereon/ Christian Schmid

Unique: samples with a diameter of one centimetre can be X-rayed and precisely imaged with an accuracy of one micrometre at the micro-tomography station.

What’s New?
With fifty megapixels, the new detectors at the “micro station” now have five times higher the resolution than the old detectors and are extremely sensitive. The samples can also be measured considerably faster using new contrast methods, whereby larger sample images are created.

Photo: Hereon/ Berit Zeller-Plumhoff

Magnesium Implant
The bone screw made of magnesium stems from the Hereon department of “Metallic Biomaterials.” In order to study how precisely the implant degrades in the bone, a sample measuring 5x5 millimetres in size is X-rayed. With the old cameras, only sections of the sample could be viewed, whereby individual images ultimately needed to be pieced together. Now the entire sample can be imaged on the computer as a three-dimensional dataset with an accuracy of a micrometre.

Photo: Hereon/ Lucian Blaga

Joining Methods
Using innovative joining processes developed at the Institute of Materials Research, the most varying materials can be joined to one another. Metals with plastic. Composite with aluminium. Or titanium with steel. The samples are X-rayed down to the smallest detail. This is how the researchers can ascertain how the materials behave during joining and can better understand the process. A composite can be seen here, created using U-Joining, a method patented by the Hereon. In this process a titanium alloy is joined to a fibre-reinforced plastic.

Nano Station

Photo: Hereon/ Christian Schmid

Whenever smaller and even more detailed images are required, thereby exceeding the capabilities of the micro station, nano-tomography is used. The samples studied here are often only as thick as a human hair. With the help of X-ray optics, structures can be imaged that are less than forty nanometres in size—that is less than a thousandth the thickness of a single hair.

What's New?
The Hereon’s Central Technical Department has constructed the new camera tower at the beamlines exactly according to the researchers’ specifications—there’s no other like it in the world! With the new camera tower, the new detectors from micro-tomography can also be used for nano-tomography. This considerably increases the flexibility of the nano-tomography. One scan would earlier take eight hours, but the new cameras only need a few minutes. This allows the researchers to measure very quickly compared to others cameras.

Photo: Hereon/ Berit Zeller-Plumhoff

Magnesium Implant
In order to study the exact corrosion processes at the interface between the screw and bone, micro-tomography Example #1 is examined again at the nano-tomography station. To do so, tiny pieces of the corrosion layer are extracted and positioned in the X-ray beam. Read the original publication (doi.org/10.1016/j.bioactmat.2021.04.009.)

Photo: Hereon/ Lucian Blaga

Butterfly Scale
Butterfly wings often gleam in the most fabulous colours—some species, such as the blue morpho butterfly, use a trick for this. They do not have any colour pigments on the scales of their wings. The scales are colourless, arranged like a fir tree. This arrangement absorbs all the colours of sunlight except blue light, which is reflected back. That is why the morpho butterfly looks blue.

Dr Elena Longo has been working for two years at the Hereon’s DESY site in Hamburg. Here she is studying the butterfly scale images with doctoral candidate Silja Flenner. Photo: Hereon/ Christian Schmid

Scientists at the University of Sheffield have studied precisely how the structure is formed with the help of Hereon’s nano-tomography station. With this knowledge, non-fading dyes can be produced.

PETRA IV

The next generation of storage ring X-ray sources is already in the planning at DESY. The beam will become even more focussed with PETRA IV. Optimised phase contrast procedures will then be possible for the Hereon researchers, something from which especially materials scientists can benefit. The new installation is to be built in the existing PETRA III ring tunnel and will begin operation in 2027. “PETRA IV and the ground-breaking nano-focussing ability will provide us with outstanding research opportunities for producing new future-oriented and resource-saving materials,” says Prof Matthias Rehahn, scientific director of the Hereon.