title: On the lifetimes and physical nature of incompletely relaxed electrons in liquid water.
abstract: Despite intense study over the past two decades, the dynamics of electron solvation in water, particularly regarding the physical properties and lifetimes of non-equilibrium, incompletely relaxed electrons, remain very controversial. Both experimental and theoretical studies have reported a very diverse range, from approximately 50 to approximately 1000 fs, for the lifetime of the p-like excited state of the hydrated electron, and the nature of incompletely relaxed states remains unclear. Here, we reveal that these controversies are to a great extent due to a hidden effect, i.e., the universal existence of a coherence spike at delay time zero in pump-probe spectroscopic kinetics traces. After removing this spike effect, we show that the intrinsic lifetimes of the two incompletely relaxed states in bulk water are 180+/-30 and 545+/-30 fs, respectively. Moreover, our results using iododeoxyuridine as a molecular probe reveal that both states are electronically excited states of the hydrated electron and the second state of a 545 fs lifetime is the long-sought wet electron. These results resolve the long-standing controversies about electron hydration dynamics.
authors.affiliation: Department of Physics, University of Waterloo, Waterloo, Ontario, CanadaN2L 3G1.
authors.forename: Chun-Rong
authors.initials: CR
authors.lastname: Wang
authors.forename: Ting
authors.initials: T
authors.lastname: Luo
authors.forename: Qing-Bin
authors.initials: QB
authors.lastname: Lu
mesh_terms: D004583:Electrons; D007065:Idoxuridine / Q000737:chemistry; D015335:Molecular Probes / Q000737:chemistry; D013053:Spectrophotometry; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D015335:Molecular Probes; D014867:Water; D007065:Idoxuridine