CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect
Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0<0.2. Thus our results callinto serious question the widespread assumption that the square rootmodel can be applied to estimate the kinetic fractionation of noble gasisotopes caused by diffusion in ambient liquid water.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Basic EnergySciences
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 929050
- Report Number(s):
- LBNL-63402; R&D Project: 468208; BnR: KC0303020; TRN: US200814%%79
- Country of Publication:
- United States
- Language:
- English
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