Resonance Raman spectra of electrons solvated in liquid alcohols
ABSTRACT Resonance Raman spectra of electrons solvated in liquid methanol, ethanol, and n-propanol are presented. At least five distinct solvent modes exhibit resonantly enhanced scattering, including the OH torsion, CO/CC stretches, the OH in-plane bend, methyl deformations, and the OH stretch. The 200-350 cm-1 frequency downshift of the OH stretch indicates a strong H-bond interaction between the electron and the hydroxyl group. The multiple modes including alkyl vibrations that are coupled to the electronic transition of the solvated electron reveal the extension of the electron's wavefunction into the alkyl solvent environment.
Chemistry Letters 01/2010; 39(7):668-670. DOI:10.1246/cl.2010.668 · 1.30 Impact Factor
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ABSTRACT: Using pump-probe transient absorption spectroscopy we studied the solvation dynamics of the electron in liquid polyalcohols: ethane-1,2-diol, propane-1,2-diol, propane-1,3-diol and propane-1,2,3-triol. First, transmission measurements allowed us to assess that electrons were produced via two-photon ionization of the solvent with 263 nm femtosecond laser pulses, and to determine the two-photon absorption coefficient of the polyols. Second, time-resolved absorption spectra ranging from 440 to 710 nm were measured. Our study shows that the excess electron in the diols presents an intense and wide absorption band in the visible and near-IR spectral domain at early time after photoionization. Then, for the first tens of picoseconds the electron spectrum shifts toward the blue domain and its bandwidth decreases as the red part of the initial spectrum drops rapidly while the blue part hardly evolves. Using Bayesian data analysis method, the observed picosecond solvation dynamics were reconstructed with three models: a two-step mechanism and two continuous relaxation models. Comparison between the ability of models to reproduce the experimental kinetics is in favor of a heterogeneous continuous relaxation. Recent results obtained in propane-1,2,3-triol show that the electron solvation dynamics is very fast in this solvent despite its high viscosity and highlight the role of the OH group in that process.Journal of Molecular Liquids 06/2008; 141(3):124-129. DOI:10.1016/j.molliq.2008.01.017 · 2.08 Impact Factor
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ABSTRACT: This calculation introduces a promising way to catalyze gas-phase SN2 reactions at a unimolecular level by using an excess electron (EE) as an “electron solvent”. The EE participation leads to very favorable energetics for the reaction, by neutralizing the created positive charge as the reaction proceeds, and by also positioning the transition state earlier. The reaction occurs via an unusual electron-transfer-coupled SN2 mechanism. EE-transfer from its binding zone to the attacking group is a key step. This work provides additional insights into the unimolecular SN2 mechanism catalyzed by an EE acting as an “electron solvent”.Computational and Theoretical Chemistry 03/2011; 964(1):72-76. DOI:10.1016/j.comptc.2010.11.038 · 1.37 Impact Factor