Isotope separation and yield calculations for vibrationally enhanced oxidation of nitrogen

Abstract

The separation of nitrogen isotopes by low temperature reaction of vibrationally excited nitrogen gas with oxygen has been studied, in which the formation of 15NO is theoretically favored. The potential yield and isotope separation coefficient β for this process were examined using a numerical simulation of the kinetic processes, which incorporated a steady-state isothermal model of the 14N2 and 14N15N vibrational distribution functions coupled with a non-steady-state kinetic model of the chemical system including N*2, O*2, N, O, and their reaction products. In the absence of O2, the vibrationally enhanced rate coefficient for the reaction N*2+O → NO+N was observed to be inversely proportional to the concentration of O atoms, due to VT loading of the N*2 distribution function. O2 was also found to greatly reduce the rate coefficient due to efficient depletion of the highly excited species via the reaction N2(v)+O2(0) → N2(v−1) +O2(1). Computed reaction yield increases dramatically if both the O*2 and N*2 vibrational temperatures are elevated, but only at the expense of greatly reduced β. The effective separative work for this process was estimated.

Carbon and Oxygen Isotope Separation by Plasma Chemical Reactions in Carbon Monoxide Glow Discharge

“…where 13 β C (PVM) is the 13 C enrichment coefficient of atomic carbon formed by reaction (6). Our experimental data indicate that reaction (6a) is the more dominant path.…”

“…This means that reaction (6) can take place only when more than 25 vibrational quanta are pooled between the two collision partners. 12) To estimate the isotopic branching ratio of reaction (6), therefore, we divide the CO molecules into two states:…”

“…Because of an abundance of the number of excited states, detailed numerical solution is needed to model the reaction (6). However, if it is assumed that degree of vibrational excitation is low, one can obtain the following relations (see Appendix):…”

“…The reaction (6) in the text has a 5.6 eV activation energy. This means that reaction (6) can take place only when more than 25 vibrational quanta are pooled between the two collision partners.…”

“…[3][4][5][6][7][8][9][10][11][12] Theoretical analyses have shown its attractive potential that in such process the reaction yield and enrichment factor are relatively high and the energy expenditure per separated atom is quite low. [3][4][5][6] And a few experimental studies have shown a high isotope enrichment potential. [7][8][9] Much of this early work is reviewed by Rich and Bergman. 11)…”