Optical spectroscopy and modeling of uranium gas-phase oxidation: Progress and perspectives

Spatiotemporal evolution of emission and absorption signatures in a laser-produced plasma

“…Optical TOF is a powerful technique for investigating velocity distribution of various species in the plasma and several authors previously used it for optimizing pulsed laser deposition (PLD) film quality and understanding plasma chemistry. 21,32,33,35,37,38 Emission and absorption TOF profiles will also provide important parameters related to the evolution of laser ablated materials such as the arrival/delay time, velocity distribution, the signal intensity and persistence at various spatial positions in the plasma. In this article, a comprehensive evaluation of kinetics of excited and ground population of Al species at various spatial points in an LPP is made by combining emission and absorption TOF combined with analysis of TRAS and OES measurements.…”

“…Active sensing methods such as laser absorption spectroscopy (LAS) and laser induced fluorescence (LIF) spectroscopy, which utilize the ground or lower level population, are useful for measuring properties of an LPP at later times of its evolution where the electronic excitation is not favored. [11][12][13][14][15][16][17][18][19][20][21] Although absorption spectroscopy is a wellestablished technique for gas sensing, its use for LPP characterization is limited and it is partly due to its active nature that necessitates the use of a light source such as laser, 22 arc lamp, 16 or frequency combs 17 for probing the absorption by the LPP species. The properties of the probe light source also dictate the experimental methodology as well as information gathered.…”

Gas-phase oxidation and nanoparticle formation in multi-element laser ablation plumes

“…In ns LA, plume chemistry (i.e., gas-phase oxidation) typically occurs at later times in plasma evolution when the plasma temperature is E8000 K or lower. 1 The alloy target was mounted inside a small chamber onto a stage for spectroscopic analysis and NP generation. Details regarding target fabrication are detailed in ESI, † Appendix S1.…”

“…Laser produced plasmas (LPPs) are highly resource efficient, repeatable, tunable, lab-scale test beds for studying chemical reactions occurring in plasmas or fireballs produced from detonation of energetic materials, and nanoparticle (NP) generation. 1,2 The generation of a LPP involves focusing a laser beam onto a target, resulting in material removal and generation of a plasma. When a laser ablation (LA) plume expands into a background gas, rapid plasma cooling occurs due to collisions with ambient gas species.…”

“…Molecular formation in LPPs is favored farther from the target at the cooler plasma periphery, at temperatures E8000 K or less. 1 At later times, NPs nucleate, grow, and coalesce, forming fractal NP agglomerates. While molecular and NP formation in LA plumes has been explored previously, [3][4][5][6][7][8][9] limited experimental work has been able to characterize gas to solid phase processes in bi-and multielement LA plumes.…”