Relativistic generation and characterization of ultrafast X-rays for time-resolved diffraction and spectroscopy

Summary form only given. Solid-target illumination with multi-terawatt ultrashort pulses can generate, through relativistic laser driven electron interactions, ultrafast pulses of 10 keV-range X-ray line radiation and 100 keV-range continuum emission with very high flux. Such pulses can be used to study a number of phenomena occurring on timescales which are to date inaccessible with synchrotron radiation and on internuclear length-scales which are difficult or impossible to access with conventional visible spectroscopy. Beyond the number of fundamental physical questions underlying relativistically driven X-ray sources, the high efficiency and comparatively low cost of this emerging technology will enable table-top time-resolved studies of atomic-scale motion during chemical reactions. In this contribution we present a detailed characterization and optimization of the experimental conditions for efficient production of short pulse X-rays to be used in time-resolved experiments. We present experimental evidence indicating that the production of K-shell holes generating line radiation arises from collisions with non-thermal electrons, and that the size of this source is on the order of the laser spot size. The combination of extremely small source size, high flux, and short time duration are ideal for time-resolved pump-probe X-ray diffraction and spectroscopic studies of crystalline and molecular dynamics.