Accession Number:

ADA621861

Title:

Computational Study of Collisions Between O(3P) and NO(2Pi) at Temperatures Relevant to the Hypersonic Flight Regime

Descriptive Note:

Interim rept. 1 Jun 2013-29 Oct 2014

Corporate Author:

AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE

Report Date:

2014-10-29

Pagination or Media Count:

17.0

Abstract:

Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O3P and NO2Pi are relevant over a wide range of temperatures. For this purpose, a potential energy surface PES for the ground state of the NO2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated 20 000 K, the rate coefficient for the O1O2N channel becomes comparable to within a factor of around three to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyis rules. However, the oxygen exchange channel NO2O1 is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.

Subject Categories:

  • Atmospheric Physics
  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE