19.2-attosecond X-ray pulse lets scientists freeze electron motion

Scientists at ICFO have developed a groundbreaking 19.2-attosecond soft X-ray pulse, the shortest and brightest of its kind ever produced, enabling real-time observation of electron dynamics with unprecedented clarity. This ultrafast pulse acts as the fastest camera to date, capturing electron motion that governs fundamental processes such as chemical reactions, energy transfer, and phase transitions. The soft X-ray light’s unique ability to fingerprint specific atoms allows researchers to track electron reorganization around individual atomic sites, providing new insights into how materials change properties and molecules transform during reactions. Achieving this milestone required significant advancements in high-harmonic generation, laser engineering, and attosecond metrology, overcoming a decade-long challenge in accurately measuring such brief pulses. The breakthrough came with a novel pulse retrieval method that confirmed the pulse duration below the atomic unit of time, a fundamental limit in ultrafast physics. This capability opens new avenues across physics, chemistry, biology, and quantum science, enabling direct observation of electron behavior at