Temperature Effect on the Absorption Spectrum of the Hydrated Electron Paired with a Lithium Cation in Deuterated Water

Abstract

The absorption spectra of the hydrated electron in 1.0 to 4.0 M LiCl or LiClO4 deuterated water solutions were measured by pulse radiolysis techniques from room temperature to 300 degrees C at a constant pressure of 25 MPa. The results show that when the temperature is increased and the density is decreased, the absorption spectrum of the electron in the presence of a lithium cation is shifted to lower energies. Quantum classical molecular dynamics (QCMD) simulations of an excess electron in bulk water and in the presence of a lithium cation have been performed to compare with the experimental results. According to the QCMD simulations, the change in the shape of the spectrum is due to one of the three p-like excited states of the solvated electron destabilized by core repulsion. The study of s --> p transition energies for the three p-excited states reveals that for temperatures higher than room temperature, there is a broadening of each individual s --> p absorption band due to a less structured water solvation shell.

Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C

“…33,36,37 To minimize the light loss due to the infrared absorption of water, D 2 O was used instead of H 2 O. The experiments were carried out on the 35 MeV Linac electron accelerator of the Nuclear Professional School, The University of Tokyo using a high temperature/ pressure irradiation cell ͑Taiatsu Techno®͒.…”

Mechanism and kinetics of hydrated electron diffusion

“…The electron, confined to the ground state, is represented by a wavefunction that corresponds to the instantaneous nuclear configuration. Our methodology has been previously employed for the hydrated electron at different thermodynamic states [30,31], in confined media [32], and in electron-cation pairs [33,34,35,36].…”

Probing the Birth and Ultrafast Dynamics of Hydrated Electrons at the Gold/Liquid Water Interface via an Optoelectronic Approach

“…It is noteworthy that the center energy of the spectral response of the e – trap and e – aq species, i.e., the S 3 and S 4 states (∼1.5 eV), appears at a significantly lower photon energy than reported in the bulk (1.7 eV), despite the large uncertainty on the exact value due to the low signal-to-noise ratio and coarse spectral resolution. The center energy of the absorption peak in the bulk shifts under the influence of a number of factors such as the electrolyte composition (nature of cations, concentration, and the ion pair formation), 61 − 63 the temperature, 64 , 65 and the isotopic effect. 63 − 65 A temperature increase causes a red shift of ∼0.3 eV per 100 K in the bulk, but the limited lattice temperature rise in our system upon laser irradiation (∼15 K, as calculated using a two-temperature model, see Supporting Information for details) fails to fully explain the observed shift and cannot account alone for the spectral shape and the dynamics.…”

“…The center energy of the absorption peak in the bulk shifts under the influence of a number of factors such as the electrolyte composition (nature of cations, concentration, and the ion pair formation), 61 − 63 the temperature, 64 , 65 and the isotopic effect. 63 − 65 A temperature increase causes a red shift of ∼0.3 eV per 100 K in the bulk, but the limited lattice temperature rise in our system upon laser irradiation (∼15 K, as calculated using a two-temperature model, see Supporting Information for details) fails to fully explain the observed shift and cannot account alone for the spectral shape and the dynamics. Moreover, the hydrated electron resides at a heterogeneous interface, where the EDL structure makes a direct comparison between the observed spectra and previous reports difficult.…”