H/D isotope effects on femtosecond electron reactivity in aqueous media

Journal Article · Wed Jan 23 23:00:00 EST 1991 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100155a010· OSTI ID:5895423

Gauduel, Y; Pommeret, S; Migus, A; Antonetti, A ^[1]

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1. Ecole Polytechnique-ENS Techniques Avancees, Palaiseau (France)

The effects of isotope substitution on the primary steps of electron reactivity in aqueous media have been investigated by using femtosecond near-infrared and visible spectroscopy. In neat deuterated water, a precursor of the hydrated electron has been identified. For both H{sub 2}O and D{sub 2}O, this localized state (e{sub prehyd}{sup {minus}}) which absorbs in the infrared is distinct from the fully hydrated state (e{sub hyd}{sup {minus}}). In neat D{sub 2}O the dynamics of electron localization is slightly slower (9%) than in H{sub 2}O; however, the lifetime of this transient electronic state (250 fs) remains similar to the analogue in light water. The absence of an H/D isotope effect on the electron hydration dynamics is confirmed in ionic aqueous media and in organized assemblies by using an anionic species (chloride ion) and a chromophore (phenothiazine), respectively, as the electron donor. In pure aqueous solutions, the changes due to isotope substitution are mainly observed during the early electron-radical pair recombination (e{sub hyd}{sup {minus}} + X{sub 3}O{sub +}, e{sub hyd}{sup {minus}} + OX with X = H or D). The percentage of hydrated electrons involved in the fast recombination is increased in D{sub 2}O. This moderate H/D isotope effect can be linked to a change in the initial spatial distribution of the electron and prototropic radicals. The analysis of the femtosecond kinetics provides evidence that the primary electron-radical pairs (e{sub hyd}{sup {minus}}{hor ellipsis}X{sub 3}O{sup +}, e{sub hyd}{sup {minus}}{hor ellipsis}OX) execute a one-dimensional (1D) walk before undergoing recombination.

• OSTI ID: 5895423
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 95:2; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
AQUEOUS SOLUTIONS
CHEMISTRY
DATA
DISPERSIONS
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HEAVY WATER
HYDROGEN COMPOUNDS
INFORMATION
INFRARED SPECTRA
ISOTOPE EFFECTS
LEPTONS
MIXTURES
NUMERICAL DATA
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
SOLUTIONS
SOLVATED ELECTRONS
SPECTRA
VISIBLE SPECTRA
WATER