Solvated Electron Systems Research Articles

Comparison of Magnetic Deflection among Neutral Sodium-Doped Clusters: Na(H2O)n, Na(NH3)n, Na(MeOH)n, and Na(DME)n.

Using a pulsed Stern-Gerlach deflection experiment, we present the results of a comparative study on the magnetic properties of neutral sodium-doped solvent clusters Na(Sol)n with n = 1-4 (Sol: H2O, NH3, CH3OH, CH3OCH3). Experimental deflection ratios are compared with values calculated from molecular dynamics simulations. NaNH3 and NaH2O are deflected as a spin 1/2 system, consistent with spin transitions occurring on a time scale significantly longer than 100 μs. For all other clusters, reduced deflection is observed. The observed magnetic deflection behavior is correlated to the number of thermally populated rotational states in the clusters. We discuss that spin-rotational couplings allow for avoided crossings and a reduction in the effective magnetic moment of the cluster. This work attempts to understand the evolution of magnetic properties in isolated weakly bound clusters and is relevant to diamagnetic and paramagnetic species expected to exist in solvated electron systems.

Solvated electrons in the complex media: a review

<p indent="0mm">Solvated electrons are a type of weakly-bound electrons which are confined in solvents or surrounding media and are different from the atomic core and valence electrons. Their main characters are that the electron(s) are solvated by solvent molecules or micro-surrounding media, and are novel entities and special quantum dot systems. They have quite unique structures, properties and dynamics, and exhibit the promising applications. In this review, we summarized the serial research progress about the solvated electrons in the complex media by our group, including the structures, states, properties, time-evolution dynamics of their character parameters in the complicated media, a series of chemical reactions and physical process associated with solvated electrons, and functionality of solvated electron systems, discussed their characteristics and regularities, and also presented the outlook for the further development of the solvated electrons.<bold> </bold>

Benchmark calculations of excess electrons in water cluster cavities: balancing the addition of atom-centered diffuse functions versus floating diffuse functions.

Diffuse functions have been proved to be especially crucial for the accurate characterization of excess electrons which are usually bound weakly in intermolecular zones far away from the nuclei. To examine the effects of diffuse functions on the nature of the cavity-shaped excess electrons in water cluster surroundings, both the HOMO and LUMO distributions, vertical detachment energies (VDEs) and visible absorption spectra of two selected (H2O)24(-) isomers are investigated in the present work. Two main types of diffuse functions are considered in calculations including the Pople-style atom-centered diffuse functions and the ghost-atom-based floating diffuse functions. It is found that augmentation of atom-centered diffuse functions contributes to a better description of the HOMO (corresponding to the VDE convergence), in agreement with previous studies, but also leads to unreasonable diffuse characters of the LUMO with significant red-shifts in the visible spectra, which is against the conventional point of view that the more the diffuse functions, the better the results. The issue of designing extra floating functions for excess electrons has also been systematically discussed, which indicates that the floating diffuse functions are necessary not only for reducing the computational cost but also for improving both the HOMO and LUMO accuracy. Thus, the basis sets with a combination of partial atom-centered diffuse functions and floating diffuse functions are recommended for a reliable description of the weakly bound electrons. This work presents an efficient way for characterizing the electronic properties of weakly bound electrons accurately by balancing the addition of atom-centered diffuse functions and floating diffuse functions and also by balancing the computational cost and accuracy of the calculated results, and thus is very useful in the relevant calculations of various solvated electron systems and weakly bound anionic systems.

Excess electron is trapped in a large single molecular cage C60F60

A new kind of solvated electron systems, sphere-shaped e(-)@C60F60 (I(h)) and capsule-shaped e(-)@C60F60 (D6h), in contrast to the endohedral complex M@C60, is represented at the B3LYP/6-31G(d) + dBF (diffusive basis functions) density functional theory. It is proven, by examining the singly occupied molecular orbital (SOMO) and the spin density map of e(-)@C60F60, that the excess electron is indeed encapsulated inside the C60F60 cage. The shape of the electron cloud in SOMO matches with the shape of C60F60 cage. These cage-like single molecular solvated electrons have considerably large vertical electron detachment energies VDE of 4.95 (I(h)) and 4.67 eV (D6h) at B3LYP/6-31+G(3df) + dBF level compared to the VDE of 3.2 eV for an electron in bulk water (Coe et al., Int Rev Phys Chem 2001, 20, 33) and that of 3.66 eV for e(-)@C20F20 (Irikura, J Phys Chem A 2008, 112, 983), which shows their higher stability. The VDE of the sphere-shaped e(-)@C60F60 (I(h)) is greater than that of the capsule-shaped e(-)@C60F60 (D6h), indicating that the excess electron prefers to reside in the cage with the higher symmetry to form the more stable solvated electron. It is also noticed that the cage size [7.994 (I(h)), 5.714 and 9.978 A (D6h) in diameter] is much larger than that (2.826 A) of (H2O)20- dodecahedral cluster (Khan, Chem Phys Lett 2005, 401, 85).

Solvent-induced electronic decoherence: Configuration dependent dissipative evolution for solvated electron systems

An electronic state and nuclear configuration dependent mechanism for electronic coherence loss is integrated into the mean field with surface hopping (MF/SH) algorithm for nonadiabatic (NA) mixed quantum–classical molecular dynamics (MQC-MD). The characteristic decoherence time scale between a pair of states is evaluated from differences in the instantaneous Hellmann–Feynman forces on the two surfaces at each phase space point along the quantum–classical trajectory. Within this instantaneous decoherence mean field with surface hopping (id-MF/SH) formalism, both the primary evolution that is responsible for transition probabilities and the auxiliary equations governing the nuclear dynamics are described by the same dissipative MQC Liouville–von Neumann equation. Decoherence, therefore, impacts both the transition probabilities and the realization of the quantum–classical trajectory. The method is implemented for the solvated electron in water and methanol and applied to trajectories describing photoexcitation of equilibrium ground-state species. Analysis reveals that, in general, both the decoherence time scale and the NA coupling increase with decreasing eigenstate energy gap. The cooperative combination of both strong coupling and large coherence as the energy levels approach each other gives rise to localized regions of comparatively higher transition probabilities. Excited-state survival probability analysis extracts a decay time of 1540 fs for the solvated electron in water and 2617 fs for the methanol case. The approximate agreement with the decay of time 2102 fs for the aqueous system, based on simulations employing a fixed 6 fs decoherence parameter, suggests that an average prescription of coherence loss may be adequate for the first-excited-state solvated electron system. The self-contained form of the id-MF/SH formalism, however, makes the new method a general approach to NA MQC-MD for condensed phase systems.

Film forming reaction at the lithium/electrolyte interface

Active metal nonaqueous systems can be divided into three groups: (a) solid electrolyte interphase (SEI)-free, aqueous-like, active-metal nonaqueous systems, such as aluminium plating baths; (b) metal solvent blue solutions, or solvated electron systems; (c) SEI battery systems. It is concluded that the only type of system that can be applied in primary and secondary lithium batteries is the SEI electrode system. The following are presented and discussed: The deposition-dissolution mechanism and the kinetics of SEI electrodes, the effect of several parameters on the resistivity of the SEI, the growth rate of the SEI, the morphology of the overall passivating layer and the voltage delay problem.

A new model of solvated-electron systems. Spectral behaviour

A new adiabatic model of infinitely dilute solvated-electron systems is described in which the solvent is accorded a dual role suggested by the experimental behaviour of the optical absorption bands attributed to solvated electrons. A small, finite number of solvent molecules and an excess electron, designated as a solvent–anionic-complex, are treated as adiabatic particles; the remaining solvent molecules, comprising a macroscopic solvating system, are treated as averageable particles. As a result, the solvated-electron absorption spectrum is determined by the intrinsic properties of the solvated solvent–anionic-complex.A basic consequence of the present model is its implication of spectral shape stability of the solvated-electron absorption band when the latter results only from a single band of discrete–continuum transitions of the electron. Under such circumstances, a linear solvated-electron–solvent energy relationship is implied.

Shape stability of solvated-electron optical absorption bands. Part 2.—Theoretical implication

The enhanced optical absorption bands attributable to solvated electrons in polar solvents often merely shift in frequency with essentially unaltered shape when the temperature and/or density of the solution are changed. The resulting spectral shape stability is examined in terms of a fundamental many-particle theory of temperature-dependent spectral moments developed recently to deal with solvated-electron absorption bands. When spectral shape stability is extrapolatable to the zero of absolute temperature the solvated-electron absorption band is found to be equivalent to one in which the radiative transitions have an essential bound–continuum nature.The theory is expressed in terms of a continuum formalism built upon an energy band structure for solvated-electron systems. Expressions for the absorption line shape are obtained which are formally similar to those obtained from various single-particle theories in which bound–unbound transitions of the absorbing particle successfully account for the shape.An extended spectral shape stability is conjectured which appears to accommodate some cases in which overall spectral shape stability does not obtain.

Solutions of Silver and Copper in Their Molten Salt Systems AgClxBr1‐x and CuClxBr1‐x

AbstractThe solubilities of the metals copper and silver in their molten salt systems AgClxBr1‐x and CuClxBr1‐x, respectively, were measured as functions of x and T. From the experimental data and using sublimation data for the metals from the literature, the enthalpies and entropies for the reaction Me(gas) → Me(dissolved)were calculated. In both systems, these solvation enthalpies and entropies do not vary monotonically with the composition parameter x of the melt, but show marked extrema at some compositions, indicating discrete structures within the solvation shell of the dissolved species.Spectroscopic investigations were made on the system Ag/AgCl. The difference spectrum between the pure melt and the metal solution shows a band at 540 nm (540°C), the intensity of which is proportional to the metal concentration. With increasing temperature, the wavelength of maximum absorption is shifted towards higher values.The influence of the dissolved metal on the electric conductivity of the melts was studied in the silver solutions as a function of T and x. In all cases, this influence was within the experimental error and definitely smaller than should be predicted on the base of a free electron model. Using the concept of electrons trapped in a cavity (spherical box with inifinite potential walls) for interpreting the spectroscopic data. one finds a cavity diameter of 7.1 A at 550°C and a thermal expansivity of the cavity of 8.1 · 10−1 K−1. In accordance with the results on other solvated electron systems, this value is higher than the macroscopic expansivity of the solvents (αv(AgCl) = 1.74 · 10−4 K−1).