Speaker: Linda Young, Argonne National Laboratory
Program Description:
X-ray free-electron lasers have revolutionized the photon science landscape in the short wavelength, short timescale and high-intensity regimes. Key science motivations include the dream of single-particle imaging at atomic resolution and the filming of “molecular movies” on their natural time (femtosecond) and length (Ångstrom) scales. As a foundation, many studies have focused on the nonlinear response of isolated atoms, molecules and clusters to intense x-ray radiation on femtosecond timescales, while simultaneously great strides have been made toward generation of attosecond pulses to reduce damage and to probe non-equilibrium processes – opening a new regime for exploration. In this talk rather than focusing on interactions with isolated particles, I will discuss our recent studies of x-ray induced phenomena in dense media. In dense gases, where an x-ray pulse can undergo substantial spectral, temporal and spatial reshaping, our studies of non-resonant and resonant propagation reveal atomic x-ray lasing, as previously observed by Rohringer and collaborators, high-resolution stimulated Raman scattering, and intensity-induced absorption lineshape modification. In liquid water, we have identified clean signatures for impulsive ionization products, e.g. the water radical cation and hydroxyl radical, prompting our campaign to systematically dissect radiolysis processes on the physico-chemical timescale in complex media with the IDREAM EFRC.
