Pulse radiolysis and laser photolysis study of solvated electron solutions in hexamethylphosphortriamide

Abstract

Laser photolysis ( Q-switched neodymium laser, 20 ns) and pulse radiolysis (2.2 μs electron pulses from a linear accelerator, dose per pulse ⋍2 krad) methods have been used in a study of the influence of light and ionizing radiation on electrochemically generated solvated electron solutions in hexamethylphosphortriamide (HMPA) at room temperature. The stoichiometry of association between e s - and metal cations (Na +) observed in the system is found to be (Na +, e 2 −2). It was found after a laser pulse that this complex with λ max = 750 nm is bleached and simultaneously a species absorbing in the i.r. (solvated electrons) is formed. The extinction coefficient of (Na +, e 2 -2) is 4 × 10 4 dm 3 mol −1 cm −1, the oscillator strength 0.7, and the quantum yield of photobleaching 0.075. The rate constant of (Na +, e 2 −2) formation K 1 = 1.2 × 10 6 dm 3 mol −1 s and the equilibrium constant between Na +, e s *minus; and the complex K ∗ = 2.3 × 10 4 dm 6 mol −2 .