Picosecond absorption studies of excess electrons in ammonia, amines, and ethers

Absorption spectroscopy data on the optical properties of the solvated electron (e_solv^-) in liquid ammonia, amines, and ethers indicate that the characteristic infrared (1500 nm) absorption of e_solv^- in NH₃ and ND₃ is homogeneous at least within the time limits of the experiment (∼10 ps). The e_solv^- ground state repopulation time observed by monitoring the bleaching of the infrared band is found to be in the subpicosecond range in all solvents studied. Quasi-free electrons are generated in methylamine by photoionization of Na^- and their solvation time is studied by following the growth of the e_solv^- absorption in the range 770-1120 nm. It is found that the solvation is complete in ≤10 ps. The transient absorption spectra of species characterized as cation-electron pairs (Na⁺, e_solv^-) are obtained through picosecond photoionization of Na^- in dimethoxyethane. Their formation time is also found to be ≤10 ps.