Lenses Provide Nano Scale X-ray Microscopy

Scientists at DESY (Germany) have developed novel lenses that enable X-ray microscopy with record resolution in the nanometre regime. Using new materials, the research team led by DESY scientist Saša Bajt from the Center for Free-Electron Laser Science (CFEL) has perfected the design of specialised X-ray optics and achieved a focus spot size with a diameter of less than ten nanometres. A nanometre is a millionths of a millimetre and is smaller than most virus particles. They successfully used their lenses to image samples of marine plankton.

Modern particle accelerators provide ultra-bright and high-quality X-ray beams. The short wavelength and the penetrating nature of X-rays are ideal for the microscopic investigation of complex materials. However, taking full advantage of these properties requires highly efficient and almost perfect optics in the X-ray regime. Despite extensive efforts worldwide this turned out to be more difficult than expected, and achieving an X-ray microscope that can resolve features smaller than 10 nm is still a big challenge.

 

The silica shell of the diatom Actinoptychus senarius, measuring only 0.1 mm across, is revealed in fine detail in this X-ray hologram recorded at 5000-fold magnification with the new lenses. The lenses focused an X-ray beam to a spot of approximately eight nanometres diameter – smaller than a single virus – which then expanded to illuminate the diatom and form the hologram

The new lenses consist of over 10 000 alternating layers of a new material combination, tungsten carbide and silicon carbide. “The selection of the right material pair was critical for the success,” emphasises Bajt. “It does not exclude other material combinations but it is definitely the best we know now.” The resolution of the new lenses is about five times better than achievable with typical state-of-the-art lenses.

We produced the world’s smallest X-ray focus using high efficiency lenses,” says Bajt. The new lenses have an efficiency of more than 80 per cent. This high efficiency is achieved with the layered structures that make up the lens and which act like an artificial crystal to diffract X-rays in a controlled way.

The researchers have reported their work in the journal Light: Science and Applications.

Source: http://www.desy.de/

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