Researchers Produce Bright X-Rays from Tabletop Lasers Instead of Very Large Facilities

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An international team of researchers affiliated with the Center for Extreme Ultraviolet Science and Technology (ERC EUV), an NSF-funded Engineering Research Center headquartered at Colorado State University, has shown that, by using ultrafast lasers with long wavelengths, bright x-ray radiation can be emitted with small-scale, relatively inexpensive equipment.


For broad applications in science, medicine, and industry, laser-like x-ray sources need to be much smaller and cheaper than the very large-scale facilities previously built. Because of the research team's work, the desired X-rays can now be produced in a device about the size of a tabletop, which scientists can use at their own facilities. Some of the many questions that can now be answered include: How fast can we store data on our hard drives and how densely can we pack that data? Can we speed up catalysis using lasers? What are the most efficient designs for solar cells and next-generation circuits? Can we consume less energy in our computers and cars by wasting less in heat? Can we manipulate electrons to steer chemical reactions? And can we implement the most powerful light-based microscope in a hospital setting, taking a three-dimensional image of the inner workings of a cell in a few minutes for disease diagnostics?


Ever since invention of the visible laser 50 years ago, scientists and engineers have been striving to extend laser technology to shorter wavelengths (i.e., the x-ray region of the spectrum). Fortunately, research at the EUV ERC—in collaboration with the Technical University Vienna, Cornell University, and the University of Salamanca—has shown that lasers with long wavelengths (i.e., in the mid-infrared region of the spectrum) can be used to produce bright x-ray radiation. This work essentially realizes a laser-like, coherent, tabletop, version of the Roentgen x-ray tube in the soft x-ray region. Moreover, the generated x-ray bursts are short enough (< 10-17 sec.) to capture all motion relevant to our natural world, even at the level of electrons.

These new x-ray sources can be powerful probes of the nanoworld, imaging thick samples and, by virtue of their short wavelengths and laser-like directed beams, imaging objects much smaller than can be seen using visible light. Unlike many other new super-resolution microscopes, x-ray microscopes do not require selective staining, labeling, or using genetic engineering to insert fluorescent proteins. Thus they are much more practical to use in, for example, a wide range of clinical diagnostic applications. Using characteristic absorption lines, x-rays can show what elements are present in a material and how those elements are chemically bound.