1. Inelastic Collisions of N2, H2, and H2+He Mixtures in Supersonic Jets by Raman Spectroscopy.
- Author
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Fernández, J. M., Fonfría, J. P., Ramos, A., Tejeda, G., Montero, S., and Thibault, F.
- Subjects
PHYSICS research ,COLLISIONS (Physics) ,FLUID dynamics ,INELASTIC scattering ,RAMAN spectroscopy - Abstract
We present a detailed study of inelastic collisions at low temperature in several supersonic jets of N
2 , H2 , and H2 +He mixtures using different nozzles and stagnation conditions. Absolute number density and rotational population data of unprecedented accuracy are measured along the jet axis by Raman spectroscopy with high spatial resolution (<5 μm) and high-sensitivity (<1 photon/sec). The experimental data are interpreted by means of a master equation describing the time evolution of the rotational populations in terms of the state-to-state rate coefficients derived from high-level quantum calculations. This combination of experimental and calculated data leads to a detailed understanding of the underlying physics, consistent with the assumed isentropic behaviour. The breakdown of rotational-translational thermal equilibrium, and its space-time evolution along the jet axis are accounted for by the microscopic (state-to-state rate coefficients) and macroscopic (flow velocity, number density, temperatures) physical quantities. A highly consistent picture, free from any additional parameters, bridges this way the microsopic and macroscopic approaches to fluid dynamics along the jet axis. [ABSTRACT FROM AUTHOR]- Published
- 2008
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