Calculation of Kinetic Data for Processes Leading to UV Signatures
Abstract
Novel state-of-the-art computational techniques were developed and validated for studying collisional processes responsible for producing infrared and ultraviolet signatures in rocket plumes. The promising new methods involve computation of cross sections and rates within a semiclassical methodology. Two of the key beneficiary programs are the SPURC and the CHARM programs which require detailed microscopic dynamical information (kinetic rates and cross sections) about such collisional processes for successful modeling of the chemistry within appropriate flowfield simulation codes. Successful prediction and interpretation of ultraviolet signatures require treating collision induced transitions between different electronic states caused by the coupling between electronic and nuclear motions in molecules during collisions. Electronic transitions bring in inherently quantum mechanical effects that have no analog in classical mechanics. The task of numerically solving the quantum mechanical equations of motion is still an unsolvable computational problem for many realistic molecular systems. The semiclassical theory is accurate enough to reproduce specific quantum mechanical features necessary, because it leads to ordinary differential equations instead of the partial differential equations of quantum mechanics. Electronic structure information required in modelling the production of candidate excited species, nitrogen, nitric oxide, and hydroxyl radical molecules in some elementary reactions was analyzed. It was determined that modern quantum chemistry can provide all the required information involving excited hydroxyl production and less extensive data for other systems.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 1989
- Accession Number
- ADA206656
Entities
People
- B. C. Garrett
- G. A. Natanson
- M. J. Redmon
- P. K. Swaminathan