Accession Number : AD0822877

Title :   LIGHT EMISSION FROM SHOCK HEATED GASES.

Descriptive Note : Final technical rept. Sep 66-Aug 67,

Corporate Author : IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (UNITED KINGDOM) DEPT OF CHEMI STRY

Personal Author(s) : Levitt, B. P. ; Parsons, A. B. ; Wright, N. ; Colgan, S. J.

Report Date : SEP 1967

Pagination or Media Count : 38

Abstract : This report covers three studies of molecular processes at high temperatures, each employing the light emitted by shock heated gases. Measurements of C2 Swan band emission during the shock pyrolysis of dilute mixtures of methane and of ethylene in argon show similar features to those observed for acetone. Equilibrium emissivities for all three molecules are in good agreement with computer calculations. For richer mixtures the endothermic fragmentation immediately behind the shock front is followed by exothermic recombination to achieve chemical equilibrium. When BrCN is dissociated in the shock tube by vibrationally unrelaxed nitrogen the electronic excitation of the CN produced is controlled by the translational temperature of the N2 rather than by the vibrational energy of the N2. The disassociation rate constant is the same for argon and for the unrelaxed nitrogen. Light emission from sulphur dioxide has been used as a translational temperature tracer to measure the vibrational relaxation time of nitrogen with differing collision partners. Results for nitrogen relaxed by N2, SO2, O2, H2, He, D2, Ar and Kr at 2500 K. have been obtained. All except SO2 and O2 are in agreement with theory for energy transfer from the translational energy of the collision partner to the N2 vibration. (Author)

Descriptors :   (*SHOCK TUBES, EMISSIVITY), (*GASES, THERMOCHEMISTRY), LIGHT, PYROLYSIS, NITROGEN, MOLECULAR PROPERTIES, HIGH TEMPERATURE, METHANE, ETHYLENES, ARGON, ACETONES, ORGANIC COMPOUNDS, EXCITATION, SHOCK WAVES, BAND SPECTRA.

Subject Categories : Test Facilities, Equipment and Methods
      Atomic and Molecular Physics and Spectroscopy
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE