Assuring that a growing global population has access to clean water will require new water treatment methods. One of these next-generation methods involves a form of iron called ferrate, which creates fewer toxic byproducts than chemicals like chlorine and is potentially cheaper and easier to deploy than complex ozone treatment systems. For ferrate to work best, however, it needs to be combined with other compounds or excited by light energy. Now, using a technique involving ultra-fast laser and X-ray pulses, a team of researchers has revealed new details about the chemical reaction that occurs when ferrate is exposed to visible and ultraviolet light.