Time of flight mass spectrometry with direct extraction of a uranium plasma

Abstract

We demonstrate a Wiley-McClaren Time of Flight Mass Spectrometer modified to allow direct extraction of ions from a laser-induced plasma. Unlike many other methods that utilize mass spectrometry to investigate laser-induced plasmas, no collisional cooling or further ionization of the plasma is required prior to acceleration, allowing measurements of the plasma ion composition to be obtained directly. Furthermore, we show using the laser ablation of gadolinium as an example that we are able to obtain the translational energy distribution of the plasma directly and infer information about the relative composition of ions within different regions of the plasma plume. The approach is then applied to laser ablation of a uranium sample as a step toward probing the chemistry under conditions relevant to a nuclear fireball for nuclear forensics applications.

Coulomb explosions dynamics

“…The observed images indicate that the molecule is preferentially ionized with the axis along the molecular backbone (between the terminal Cl atoms) parallel to the polarization of the laser field. For processes (1), this results in the product ions travelling primarily parallel to the polarization vector. For the Coulomb explosions of more highly charged CCSC n+ which substantially contribute to the smaller fragment images (as examined below), the observed anisotropic distributions arise from the Cl + ions being propelled along the molecular axis while CO + and S + are pushed to the sides by electrostatic repulsion.…”

“…Table 5. 1 Bonding and non-bonding distances in the geometry optimized structure of anti and gauche conformers of oxalyl chloride.…”