A SHOCK TUBE STUDY OF THE COUPLING OF THE 02-Ar RATES OF DISSOCIATION AND VIBRATIONAL RELAXATION
Research rept. no. 125
AVCO EVERETT RESEARCH LAB INC EVERETT MA
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The purpose of this investigation was to determine how the dissociation rate will be affected by a lack of vibrational equilibrium. Studies of the dissociation rate of dilute O2 - Ar mixtures were made in a 24 in. diameter shock tube from 5000 - 18,000 deg K. The O2 concentration was monitored by its absorption of 1470A radiation. An Arrhenius plot of the data yielded a straight line from 5000 - 11,000 deg K, the rate constant being given by kd 2.9 12 x 10 to the 14th power exp -DRT ccmole-sec. Above 11,000 degrees the data deviate from the line given by this equation - at 18000 degrees kd being .45 times the calculated value. An incubation time, t, was observed during which dissociation does not proceed to a significant extent. The ratio of this incubation time to the vibrational relaxation time obtained by extrapolating Camacs low temperature results when plotted against translational temperature, displays a slight negative temperature dependence. At 18,000 degrees t v0.4, at 8000 degrees t v1, and at 5500 degrees we estimate that t v 2.
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