1. Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C.
- Author
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Jay-Gerin, Jean-Paul, Mingzhang Lin, Katsumura, Yosuke, Hui He, Muroya, Yusa, and Meesungnoen, Jintana
- Subjects
ELECTRONS ,ABSORPTION ,SPECTRUM analysis ,RADIATION chemistry ,MICROSCOPICAL technique - Abstract
The optical absorption spectra of the hydrated electron (e
aq - ) in supercritical (heavy) water (SCW) are measured by electron pulse radiolysis techniques as a function of water density at three temperatures of 380, 390, and 400 °C, and over the density range of ∼0.2–0.65 g/cm3 . In agreement with previous work, the position of the eaq - absorption maximum (EA ) is found to shift slightly to lower energies (spectral “redshift”) with decreasing density. A comparison of the present Emax A -density data with other measurements already reported in the literature in subcritical (350 °C) and supercritical (375 °C) water reveals that at a fixed pressure, Emax A decreases monotonically with increasing temperature in passing through the phase transition at tmax c . By contrast, at constant density, EA exhibits a minimum as the water passes above the critical point into SCW. These behaviors are explained in terms of simple microscopic arguments based on the crucial role played by local density and configurational fluctuations (associated with criticality) in providing pre-existing polymeric clusters, which act as trapping sites for electrons. [ABSTRACT FROM AUTHOR]max - Published
- 2008
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