Absorption of X-Rays by Nanoparticle Aggregates

In a series of recent synchrotron radiation experiments, [1-3] the absorption of high energy x-ray and VUV photons by flame generated soot nanoparticle aggregates has been examined. The structure of these aggregates is similar to that of dust grains found in interstellar clouds and processing plasmas. It is found that an intense ionisation process is produced by the absorption of an x-ray photon. The mechanism for this ionisation has been given by astrophysical models that predict that the dust grain disintegrate due to runaway electrostatic charging. The results of a small angle scattering measurement will be presented that reveal the diameters of the primary and sub-primary particles in the aggregates. 1. J. B. A. Mitchell et al Combustion and Flame, 131 (2001) 308. 2. J. B. A. Mitchell et al Astronomy and Astrophysics 386 (2002) 743. 3. J.L. LeGarrec et al Nucl. Instrumen. Meth. B 222 (2004) 130