Photodissociation of Unsaturated Alcohols. Energy Distribution in the Nascent OH Radicals

Abstract

The photodissociation of allyl and propargyl alcohols at 193 nm, which involves π−π* electronic transition and leads to the formation of OH, has been studied by using a laser photolysis−laser-induced fluorescence technique. The nascent OH radicals formed from both these molecules are found to be rotationally and vibrationally excited. The vibrational distributions are found to be similar, described by vibrational temperatures of 2070 ± 380 and 2130 ± 440 K for allyl and propargyl alcohols, respectively. The rotational temperatures of both v‘ ‘ = 0 and 1 levels of OH radicals from allyl alcohol are found to be almost the same, viz., 1960 ± 150 and 1900 ± 250 K, respectively, and close to the vibrational temperature. On the other hand, the rotational temperatures of OH radicals, 1760 ± 130 K at the v‘ ‘ = 0 level and 690 ± 120 K at the v‘ ‘ = 1 level, are very different from each other, in the case of propargyl alcohol. In both molecules, a significant part of the available energy is partitioned into the re...