CHEMI-IONIZATION IN THE SPACE ENVIRONMENT- THERMOCHEMISTRY, REACTIVITY, AND DYNAMICS
Abstract
The US Space Force has explored Active Control in the Ionosphere, designed to enhance satellite communications. In this process, chemi-ionization (CI) reactions of atomic metals with oxygen atoms in the ionosphere can form enhanced plasma densities, potentially mitigating scintillation effects that interfere with satellite communications. Underscoring the need for fundamental information regarding such reactions are atmospheric release studies involving the lanthanide (Ln) samarium (Sm), which failed to proceed as expected. This failure demonstrated that literature data regarding the thermochemistry, reactivity, and dynamics of Sm oxidation (and probably other lanthanides) were inaccurate. These studies highlighted the potential importance of excited electronic states of lanthanides and alternative reactions with multiple atmospheric gases at the elevated temperatures characteristic of the thermite reaction used to generate the atomic metals. To acquire more accurate information on Ln oxidation, our research will examine reactions of atomic Ln+ cations and their oxides with atmospheric gases (e.g., O2, CO, CO2, O3) and collision-induced dissociation (CID) of the metal oxide cations. Notably, our research examines these reactions as a function of kinetic energy using guided ion beam tandem mass spectrometry (GIBMS) such that the high-temperature conditions associated with the thermite reaction can be probed directly. These reactions are of direct interest in understanding the chemistry of lanthanides exposed to the atmosphere at high temperatures. Further, analysis of the kinetic energy dependent data provides quantitative bond energies of a variety of species, yielding a better fundamental understanding of the chemical properties of Ln and LnO. Both the kinetic and thermodynamic data are useful in modeling and predicting the chemistry of these species in the atmosphere. Furthermore, because such heavy metals exhibit extensive spin-orbit interactions, exploration of these systems will provide fundamental information needed to better understand and model the chemistries of these heavy elements and also contribute to a much better understanding of spin-orbit coupling in reactions of heavy elements, a topic that is not quantitatively understood. Accurate quantum chemical calculations on heavy metal species are problematic because they require consideration of relativistic effects under conditions where electron correlation is also important. These challenges are exacerbated by a shortage of accurate quantitative information on heavy metal molecules, making validation of approximations employed difficult. The present proposal aims to determine accurate thermochemical data that can benchmark these advanced quantum chemical methods. Routine comparisons will be conducted in house, but collaborations with theoretical collaborators will also engage state-of-the-art computational methods. Accompanying its scientific merit is the fact that this work will involve the education of graduate and undergraduate students in lanthanide science and experiments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 06, 2024
- Source ID
- FA95502310332
Entities
People
- Peter Armentrout
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Utah