Crossed-Beam Imaging of the Reaction of OH with Propanol Isomers.

Abstract

We present a crossed-beam imaging study of the reactions of OH radicals with 1- and 2-propanol at a collision energy of 8 kcal mol-1 using 157 nm probe of the radical product. Our detection is selective for the α-H and β-H abstraction in the 1-propanol case and for the α-H abstraction only in the 2-propanol case. The results show direct dynamics. A sharply peaked backscattered angular distribution is seen for the 2-propanol system and broader backward-sideways scattering for 1-propanol consistent with the different abstraction sites. The translational energy distributions peak at ∼35% of the collision energy, far from the heavy-light-heavy kinematic propensity. As this is ∼10% of the available energy, substantial vibrational excitation in the water product is inferred. The results are discussed in relation to analogous OH + butane and O(3P) + propanol reactions.