Femtosecond pH jump: dynamics of acid—base reactions in solvent cages

Abstract

Studies are reported of the dynamics of proton-transfer reactions, with sub-picosecond time resolution, in solvent cages. The acid—base system studied in a molecular beam is 1-naphthol as a solute and ammonia (or water) as a solvent, with the number of solvent molecules (n) varying. At the threshold (n=3) for proton transfer we examine the accurate form of the decay, which has an apparent biexponential character, and we relate it to the nature of deprotonation and recombination. From studies of the effect of the total energy, isotope substitution and solvent number (n), we discuss the nature of the transfer and the interplay between the local structure of the base solvent and the dynamics