Scientists at the Lawrence Berkeley National Laboratory in Berkeley, Calif., have generated a 300-fs-pulse x-ray for studying the motion of atoms during ultrafast physical and chemical processes. According to a paper published in Science, the team created the beams by sending a short, powerful pulse of infrared laser light across the path of a narrowly focused electron beam. Such pulsed x-rays are important tools in investigating the atomic structure of matter because they interact directly with nuclei and core electrons. With femtosecond x-ray pulses, scientists can track the movement of atoms in a sample during a phase transition or during a chemical or physical reaction.