Ab initio study of nitrogen and position-specific oxygen kinetic isotope effects in the NO + O3 reaction.

摘要: Ab initio calculations have been carried out to investigate nitrogen (k15/k14) and position-specific oxygen (k17/k16O & k18/k16) kinetic isotope effects (KIEs) for the reaction between NO O3 using CCSD(T)/6-31G(d) CCSD(T)/6-311G(d) derived frequencies in complete Bigeleisen equations. Isotopic enrichment factors are calculated be -6.7‰, -1.3‰, -44.7‰, -14.1‰, -0.3‰ at 298 K reactions involving 15N16O, 14N18O, 18O16O16O, 16O18O16O, 16O16O18O isotopologues relative 14N16O 16O3 isotopologues, respectively (CCSD(T)/6-311G(d)). Using our KIEs, a model was constructed Kintecus, which estimates overall isotopic associated with unreacted transferred NO2 -19.6‰  -22.8‰, respectively, (CCSD(T)/6-311G(d)) tends agreement previously reported experimental data. While this result may fortuitous, suggests that is capturing most important features of underlying physics KIE (i.e., shifts zero-point energies). The KIEs will useful future NOx modeling studies aimed at understanding processes responsible observed tropospheric variations as well nitrate.