Vibrational relaxation times in some hydrocarbons in the range 300–900°K

Abstract

Vibrational relaxation times were determined in methane, ethylene, acetylene, and cyclopropane in the temperature range 300–900°K. The experiments were performed by measuring the absorption and dispersion of ultrasonic waves passing through the vapor. For all four vapors, the vibrational relaxation time τν (sec) was found to vary with temperature T(°K) according to the relationship log10(τν P) = aT−1/3 − b, where P is the pressure (atm) and a and b are constants. The results of the present measurements were also found to be in good agreement with existing data.