Kelly Gaffney
Professor Gaffney directs the Linac Coherent Light Source (LCLS), an internationally leading research facility open to users from around the world. LCLS, the world’s first Ångström wavelength x-ray laser, has driven a revolution in x-ray science. The x-rays pulses produced by LCLS have a peak brightness a billion times brighter than those produced by conventional sources, such as a synchrotron. The first generation of LCLS enabled unique science opportunities driven by the ultrashort duration of the intense x-ray pulses generated by LCLS – durations from tens of femtoseconds to hundreds of attoseconds. This has enabled the functional dynamics of biological, chemical, and materials systems to be captured with atomistic resolution without blurring in space or time.
LCLS has now initiated a second revolution in x-ray laser science, by building a superconducting accelerator for x-ray generation, in addition to the normal conducting accelerator used for the first generation of x-ray laser operations. This new accelerator maintains the peak brightness of the normal conducting accelerator, but enables the repetition rate to be increased from 120 Hz to 1 MHz and enables a four-orders of magnitude increase in average brightness. This new source has the potential to transform x-ray imaging and high resolution x-ray spectroscopy.
Professor Gaffney also leads a research team focused on femtosecond resolution measurements of chemical dynamics in complex condensed phase systems. This research takes advantage of recent advances in ultrafast x-ray lasers, like the LCLS, to directly observe chemical reactions on the natural time and length scales of the chemical bond – femtoseconds and Ångströms. This research focuses on the discovery of design principles for controlling the non-equilibrium dynamics of electronic excited states and using these principles to spark new approaches to light-driven catalysis in chemical synthesis.
Areas of Interest and Research
My research group makes stroboscopic movies of condensed phase chemical transformations with atomic specificity and resolution. We use femtosecond optical and x-ray lasers to measure the ultrafast dynamics of electronic and vibrational degrees of freedom in a wide range of systems.
Our current research emphasizes experimental assessments of novel design concepts for light-driven chemical transformations using transition metal complexes. This research targets the detailed characterization of electronic excited state trajectories as a key metric for understanding how variations in electronic ground state properties influence electronic excited state photochemistry and photophysics. In these studies we utilize steady state and time resolved optical and x-ray spectroscopy, as well as x-ray scattering.
