Ultrafast X-Ray Scattering of Xenon Nanoparticles: Imaging Transient States of Matter

Abstract

Femtosecond x-ray laser flashes with power densities of up to 10(14) W/cm(2) at 13.7 nm wavelength were scattered by single xenon clusters in the gas phase. Similar to light scattering from atmospheric microparticles, the x-ray diffraction patterns carry information about the optical constants of the objects. However, the high flux of the x-ray laser induces severe transient changes of the electronic configuration, resulting in a tenfold increase of absorption in the developing nanoplasma. The modification in opaqueness can be correlated to strong atomic charging of the particle leading to excitation of Xe(4+). It is shown that single-shot single-particle scattering on femtosecond time scales yields insight into ultrafast processes in highly excited systems where conventional spectroscopy techniques are inherently blind.

Explosion, ion acceleration, and molecular fragmentation of methane clusters in the pulsed beam of a free-electron laser

“…The core of such large objects expands hydrodynamically due to the growing electron pressure within [17,18]. Theoretical studies predict a * Electronic address: nicusor@xray.bmc.uu.se transition from Coulomb explosion to hydrodynamic expansion with increasing sample size [13].The study of Coulomb explosion of molecular clusters with intense infrared lasers has shown the advantage of using heteronuclear molecules, such as CH 4 or CD 4 , to analyze the dynamics of the explosion [22,23]. In a heteronuclear cluster, the light ions can gain additional energy during the explosion by interacting with multiply charged heavy ions (C n+ ).…”

Plasma-Formation Dynamics in Intense Laser-Droplet Interaction

“…In fact, standard Mie scattering theory assuming a homogeneous, overdense plasma sphere was used to characterize rare gas clusters in recent experiments on a shot-to-shot basis [7,8]. However, inside such a sphere, standard Mie theory would predict electric fields only within a narrow skin layer while, in this Letter, we will show that a highly inhomogeneous and temporally changing charge density distribution may be created in the droplet interior.…”

Atomistic three-dimensional coherent x-ray imaging of nonbiological systems

“…Rare gas clusters, bound by easy-to-model van der Waals forces, have traditionally served as testbeds as intense lasers have evolved from optical to x-ray wavelengths [10,38,[57][58][59][60][61][62][63][64]. FEL-induced transient dynamics in rare gas clusters have been observed in imaging experiments in the XUV [65] and, more recently, in the x-ray regime [66] providing evidence for femtosecond time scale electronic damage.…”