H/D isotope effects in water radiolysis. 2. Dissociation of electronically excited water

Journal Article · Thu Jul 26 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100378a041· OSTI ID:6187211

Han, Ping; Bartels, D M ^[1]

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1. Argonne National Lab., IL (USA)

The authors present pulsed EPR measurements of the H{sm bullet} and D{sm bullet} atom magnetization signals present immediately (within 30-50 ns) after radiolysis of alkaline H{sub 2}O/D{sub 2}O mixtures with short pulses of 3-MeV electrons. The H{sm bullet} and D{sm bullet} spectra are initially polarized by radical pair chemically induced dynamic electron polarization (CIDEP) from spin-dependent recombination reactions in the spurs. The relative amplitudes of the H{sm bullet} and D{sm bullet} spectra are analyzed to deduce the relative isotope effect {alpha} = (H/D){sub product}/(H/D){sub water} in the formation of atomic hydrogen. The atomic hydrogen (deuterium) formed in water radiolysis spurs arises from both direct dissociation of electronically excited water and from the recombination of solvated electrons with hydronium ions. In sufficiently alkaline solution, the hydronium ion can be scavenged to prevent H{sm bullet} formation by cross-recombination in spurs. The value of {alpha} determined in this limit is characteristic of the excited water dissociation. The authors find {alpha} = 2.4 {plus minus} 0.2 in a 20% H{sub 2}O/80% D{sub 2}O mixture containing 10{sup {minus}2}-10{sup {minus}1} M hydroxide.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6187211
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:15; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA ANALYSIS
DECOMPOSITION
ENERGY RANGE
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
INFORMATION
ISOTOPE EFFECTS
MEASURING INSTRUMENTS
MEASURING METHODS
MEV RANGE
MEV RANGE 01-10
NUMERICAL DATA
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOLYSIS
WATER