Singlet and triplet excited-state formation in high-energy electron tracks in liquid cis- and trans-decalin as studied by product formation in radiolysis and photolysis

Abstract

The yields of products formed as a result of irradiation of liquid cis- and trans-decalin with γ-rays and 3 MeV electrons as well as with 7.6 eV photons have been determined by means of gas–liquid chromatography (GLC). The major products for both cis- and trans-decalin are hydrogen, unsaturated C₁₀ products and dimers; in the case of cis-decalin, cis–trans isomerization takes place via a chain reaction. Singlet and triplet excited states are formed by direct excitation and by charge recombination in the tracks of high-energy electrons. The product formation resulting from the singlets is determined by the photolysis. From a knowledge of the total yield of singlets from the radiolysis, the contribution of the singlet excited states to product formation during radiolysis is calculated and the remaining products are assigned to the triplets.

For the sum of the yields of singlets and triplets a value of 6.4 (100 eV)^–1(= 6.6 × 10^–7 mol J^–1) is found for cis-decalin and 6.0 (100 eV)^–1(= 6.2 × 10^–7 mol J^–1) for trans-decalin and for the singlet fractions 0.53 and 0.47 in cis- and trans-decalin, respectively. The probability of C—H bond breakage in the singlet and triplet states is 0.42 and 0.82, respectively, for cis-decalin and 0.50 and 0.94, respectively, for trans-decalin.