NSF Award
1912527
Atmosphere and soil degradation is strongly related to emission of pollutants from combustion of fossil fuels. These pollutants, mainly volatile organic compounds, are toxic gases that participate in the formation of ground level ozone and cause stratospheric ozone layer depletion. The main toxic gases emitted by industry, power stations, and vehicles, are Nitrogen oxides (NOx) and Sulphur dioxide (SO2). Nitrogen oxides can be easily converted into gaseous nitric acid and other organic nitrates in the air contributing to irrespirable particle levels in the atmosphere. SO2 is itself a major air pollutant with similar negative impacts on the environment and animal life, including humans. Pulse electron beams have recently been proposed to clean up emissions from power plants, thereby representing a promising and cheap technique to scrub toxic molecules at combustion level without any byproducts. As an electron from the beam collides with a NOx or SO2 molecule, it can be captured forming a temporary negative ion, eventually leading to instabilities responsible for molecular dissociation in a process known as "dissociative electronic attachment." The present project aims to investigate how effectively pulse electron beams can cause the dissociation of these toxic gases thereby reducing their emission. At the end of this project we expect to have improved the understanding of these reactions and paved the way for future techniques to clean dangerous gas emissions using electron beams. At the same time, the project will create training and educational opportunities for undergraduate students to learn and get involved in state-of-the-art computational quantum chemistry techniques.<br/><br/>The researchers will study the dissociative electronic attachment mechanism of NO2 and SO2, from the electron capture step all the way to the dynamics of the dissociating fragments. This research will provide cross sections and their dependence on the initial molecular vibrational state. In order to obtain the cross sections, the electronic structure of the molecule and the temporary negative molecular ion states will be characterized. Then, the results of these calculations will be used to construct the possible energetic routes the system can take in order to dissociate. The calculations will also be used to compute angular distribution of the molecular fragments, and the results will be compared against experimental works with high angular resolution of fragment detection.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
