Ultrafast laser excitation can drive materials into exotic states beyond thermodynamic limits, offering alternative ways to control how matter stores and releases energy. Yet, whether light can actively steer energy-relaxation pathways during structural transitions remains unclear due to the lack of direct experimental evidence. Here we show, using single-pulse time-resolved X-ray imaging of gold nanorods, that photoinduced localized surface plasmons control ultrafast energy relaxation into distinct deformation modes, transverse or longitudinal deformation modes, each accompanied by characteristic plasmon-induced oscillatory distortions depending on the laser fluence. Numerical simulations further confirm that localized surface plasmons dictate ultrafast energy relaxation process from photoexcited hot electrons to anharmonic nanocrystal deformations. Our results provide direct evidence that surface plasmon-mediated interactions enable ultrafast, nanoscale control of materials’ energetics, opening a pathway for tailoring energy-transfer processes with femtosecond laser fields. This approach lays the foundation for customizing nonequilibrium phase dynamics at the nanoscale and provides a route to tailoring energy-transfer processes using femtosecond laser fields. Ultrafast lasers can drive materials into states beyond equilibrium. Here, the authors use single-pulse X-ray imaging to show that surface plasmons channel energy relaxation into distinct pathways, leading to different shape deformations.

Research on mammalian cardiac and skeletal muscle spans fields such as exercise physiology, longevity science, and inherited myopathies. Muscle is composed of many repeating contractile units, called…

On 6 May 1952, at King’s College London in London, England, Rosalind Franklin photographed her fifty-first X-ray diffraction pattern of deoxyribosenucleic acid, or DNA. Photograph 51, or Photo 51, rev...