Borsarelli CD, Bertolotti SG, Previtali CM. Thermodynamic changes associated with the formation of the hydrated electron after photoionization of inorganic anions: a time-resolved photoacoustic study.
Photochem Photobiol Sci 2003;
2:791-5. [PMID:
12911229 DOI:
10.1039/b302050a]
[Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enthalpy and volume changes, deltaH and deltaV, associated with the 266 nm laser-induced photoionization reactions of aqueous ferrocyanide and iodide ions, to yield the hydrated electron, e(-)aq, and oxidized products were determined by temperature-dependent time-resolved photoacoustics. The photoionization quantum yield as function of temperature (9-30 degrees C) was determined by laser flash photolysis actinometry. The obtained values were used for the calculation of thermodynamic parameters associated with the formation of e(-)aq, such as the apparent partial molar volume, V(o)e = 26 cm3 mol(-1), and the standard formation enthalpy and entropy changes, deltaH(o)f,e = 31 kJ mol(-1) and TdeltaS(o)f,e = 338 kJ mol(-1). These results indicate that the formation of the aqueous excess electron solution is governed by the increase in entropy in the three-dimensional hydrogen-bonding network of water.
Collapse