Electrons, ions and excited states in the pulse radiolysis of tetrahydrofuran

Abstract

Pulse radiolysis of tetrahydrofuran (THF) gives a transient absorption at long wave-lengths which is attributed to the solvated electron. When pyrene or anthracene is present their anions are formed with immediate yields of 0.66 and 0.70 when measured on microsecond time scales. These are considered to give the “free ion” yield. On nanosecond time scales, immediate yields are much higher, and there is an initial rapid decay of the anion which is attributed to ion recombination in the spurs. Lithium aluminium hydride, even on microsecond time scales, gives increased initial anion yields and longer anion lifetimes. At high concentrations G(anion)= 2.6 is attained. This is considered to be the primary ion pair yield in liquid THF and agrees with that derived from γ-radiolysis measurements. Anthracene gives G(A^S)= 0.1 and G(A^T)= 0.04, values which do not vary with anthracene concentrations over the range 5 × 10^–4–10^–2 M.