Isomerization of 1-Methylcyclobutene by Single Collision Activation at a Surface. Variation of Initial Energy

Article abstract of DOI:10.1021/j100221a025

The reaction probability per collision, P_c, for 1-methylcyclobutene activated at a hot seasoned fused silica surface has been measured under single collision conditions over the reactor temperature range T_r = 480-800 K.The initial thermal vibrational energy population distribution of the cyclobutene molecules was varied from T_c = 273 K to T_c 570 K.The reaction is isomerization to isoprene.Mixed samples of 1-methylcyclobutene and cyclobutene (which had been studied earlier) were used for internal comparison under the same conditions.These experiments provide a test of the relative suitability of various analytical forms for the collisional transition probability matrix P.Stochastic calculations with a Gaussian form provide the best overall fit to the data.The calculated average amount of energy (<ΔE'>_E0) transferred from the hot molecules in a vibrational down transition from the reaction threshold energy level, E₀, declined from 7220 to 3890 cm^-1 with increase in surface temperature from 600 to 800 K.The experimental collisional efficiency, β₁, declined from 0.39 to 0.035 over the combination temperature range T_r,T_c = 600,500 to 800,293.Strong collider behavior was observed with both 1-methylcyclobutene and cyclobutene for T_r less than 450 K.