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An X-ray laser, upgraded to become the most powerful in the world, produced its first beams on 12 September. Located in Menlo Park, California, the laser will produce one million X-ray pulses per second when running at full capacity. Scientists are excited to get a crack at the instrument, called LCLS-II, which will make it possible to create high-speed movies of ultrafast processes, including electrical charges hopping around atoms during a chemical reaction. Such studies could unlock the secrets of photosynthesis and aid in the development of new electronic materials for computing systems.