Collisional relaxation of vibrational energy transients in the methylcyclopropane system. A variable encounter method study

摘要

The variable encounter method has been used to study vibrational energy transients in the isomerization of methylcyclopropane to various butenes. This system was studied with reactor surface temperatures of 800 to 1130 K and average numbers of collisions per encounter with the reactor of 5.6 and 20.0. The reaction rate was treated on the basis of total, rather than individual butene rates, because of butene product interconversion. An exponential model of energy transfer was found to fit to the data with the average down step energy lang;Dgr;Eprime;rang; decreasing from 1860 to 1415 cmminus;1with increase of temperature over the range studied. Incubation times increased from 14 to 19 collisions with increase in temperature, and these times, together with values of the conventional relative collision efficiency bgr; and values of lang;Dgr;Eprime;rang;, are compared with those of other molecules studied by VEM. The calculated transient population distributions and the associated sequential reaction probabilities are also displayed.