Hydrogen forms in water by proton transfer to a distorted electron.
Solvated electrons are ubiquitous intermediates in radiation-induced processes, with their lifetime being determined by quenching processes, such as the direct reaction with protons under acidic conditions. Ab initio molecular dynamics simulations allow us to unravel with molecular resolution the ultrafast reaction mechanism by which the electron and proton react in water. The path to a successful reaction involves a distortion and contraction of the hydrated electron and a rapid proton motion along a chain of hydrogen bonds, terminating on the water molecule most protruding into the electron cloud. This fundamental reaction is thus decidedly shown to be of a proton-transfer rather than electron-transfer character. Due to the desolvation penalty connected with breaking of the hydration shells of these charged particles, the reaction is, however, not diffusion-limited, in agreement with the interpretation of kinetics measurements.
Marsalek
Ondrej
O
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic.
Frigato
Tomaso
T
VandeVondele
Joost
J
Bradforth
Stephen E
SE
Schmidt
Burkhard
B
Schütte
Christof
C
Jungwirth
Pavel
P
D003198:Computer Simulation; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011522:Protons; D014867:Water / Q000737:chemistry*
D011522:Protons; D014867:Water; D006859:Hydrogen