Radiation Chemistry at the RCDC

Data on short-lived chemical species have been documented at the RCDC in critically evaluated compilations on kinetics and other properties of transients from water and from inorganic and organic solutes. A bibliographic database was developed and it has been maintained and used to provide information services. The database also supports compilation activity on excited-state processes, mainly from photochemistry and photophysics.

Data compilations currently derive from two main areas:

  1. Radical kinetics in solution
  2. Thermodynamic and spectroscopic properties of free radcials

Rate constants for radical processes can be found through the NDRL/NIST Solution Kinetics Database on your personal computer. Printed compilations are found in the Journal of Physical and Chemical Reference Data and the NSRDS-NBS report series.


Kinetics of Radical Processes

Oxygen radicals (such as superoxide, hydroxyl, organic peroxyl, and singlet oxygen) have been the subject of several of our published critical compilations and their rate constants are included in the NDRL/NIST Solution Kinetics Database. Also present in the database are kinetic data from compilations on inorganic radicals and carbon-centered radicals, along with new data from the literature from ongoing compilation and evaluation efforts.

Rate constants for primary radicals from the radiolysis of water, including hydrated electrons, hydrogen atoms, and hydroxyl radicals, were critically reviewed in a 1988 compilation. A compilation of kinetic data for nonmetallic inorganic radicals in solution was published in 1988. A recently completed compilation covers rate constants for metal transients in aqueous solution. Rate constants for chemical species of special interest for environmental and biological applications, such as nitric oxide, are being evaluated for addition to the database.

A compilation of kinetic data for aliphatic carbon-centered radicals in aqueous solution is being completed for publication.


Thermodynamic and Other Properties of Radiation Induced Transients

Thermodynamically-reversible one-electron reduction potentials of many couples involving unstable radicals have been measured using pulse radiolysis and flash photolysis. A critique of methods for measurement of reduction potentials involving free radicals in aqueous solution was published along with a compilation of the data.

Some earlier data compilations at the RCDC covered: absorption spectral data for transient inorganic radicals, electron mobilities and free ion yields, the radiolysis of selected substances (methanol, ethanol, nitrous oxide and ammonia) with G values (radiation yield).

  • Reduction Potentials of One-Electron Couples Involving Free Radicals in Aqueous Solution
    P. Wardman, J. Phys. Chem. Ref. Data 18 1637-1755 (1989)__ Ordering info.

  • Optical Spectra of Nonmetallic Inorganic Transient Species in Aqueous Solution G.L. Hug, NSRDS-NBS 69 (1981)


NDRL/NIST Solution Kinetics Database

The NDRL/NIST Solution Kinetics Database includes chemical kinetic data for free radical processes involving primary radicals from water, inorganic radicals and carbon-centered radicals in aqueous solution, and organic peroxyl radicals in various solvents. The database currently functions on any MS-DOS or PC-DOS computer.

More information about just what's in the database and what's required to run it is available or if you want to go ahead and order it ...


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This document prepared by Ian Carmichael and Alberta B. Ross
e-mail: rcdc @rcdvax.rad.nd.edu

Work supported by:

Office of Basic Energy Sciences
United States Department of Energy
Last Update: K.P. Madden / 960206