Time-Dependent Radiolytic Yields of the Solvated Electrons in 1,2-Ethanediol, 1,2-Propanediol, and 1,3-Propanediol from Picosecond to Microsecond

Ultrafast Decay of the Solvated Electron in a Neat Polar Solvent: The Unusual Case of Propylene Carbonate

The behavior of carbonates is critical for a detailed understanding of aging phenomena in Li-ion batteries. Here we study the first reaction stages of propylene carbonate (PC), a cyclical carbonate, by picosecond pulse radiolysis. An absorption band with a maximum around 1360 nm is observed at 20 ps after the electron pulse and is shifted to 1310 nm after 50 ps. This band presents the features of a solvated electron absorption band, the solvation lasting up to 50 ps. Surprisingly, in this polar solvent, the solvated electron follows an ultrafast decay and disappears with a half time of 360 ps. This is attributed to the formation of a radical anion PC(-•). The yield of the solvated electron is low, suggesting that the radical anions are mainly directly produced from presolvated electrons. These results demonstrate that the initial electron transfers mechanisms are strongly different in linear compared with cyclical carbonates.

Solvation dynamics of electron produced by two-photon ionization of liquid polyols. III. Glycerol

The solvation dynamics of excess electrons in glycerol have been measured by the pump-probe femtosecond laser technique at 333 K. The electrons are produced by two-photon absorption at 263 nm. The change in the induced absorbance is followed up to 450 ps in the spectral range from 440 to 720 nm. The transient signals of electron solvation have been analyzed by two kinetic models: a stepwise mechanism and a continuous relaxation model, using a Bayesian data analysis method. The results are compared with those previously published for ethylene glycol (J. Phys. Chem. A 2006, 110, 175) and for propanediols (J. Phys. Chem. A 2007, 111, 4902). From the comparison, it is pointed out that solvation dynamics in glycerol is very fast despite its high viscosity. This is interpreted as the existence of efficient traps for the electrons in glycerol with low potential energy. The small shift of the absorption band of the excess electron indicates that the potential of these traps is very close to that corresponding to the fully solvated electron.

Solvation dynamics of electron produced by two-photon ionization of liquid polyols. II. Propanediols

Temporal evolution of transient absorption spectra of electrons produced by two-photon ionization of two isomers, propane-1,2-diol (12PD) and propane-1,3-diol (13PD), with 263 nm femtosecond laser pulses has been studied on picosecond time scale. The two-photon absorption coefficients of 12PD and 13PD at 263 nm were determined to be beta = (2.0 +/- 0.3) x 10(-11) and (2.4 +/- 0.3) x 10(-11) m W(-1), respectively. Time-resolved absorption spectra ranging from 440 to 720 nm have been measured, showing a blue shift for the first tens of picoseconds for both solvents. However, the observed solvation dynamics of electron appears faster in 13PD than in 12PD. The transient signals of electron solvation have then been reconstructed with different models (stepwise mechanism or continuous relaxation model) using a Bayesian data analysis method. Results are discussed, compared with those previously obtained in ethylene glycol (J. Phys. Chem. A 2006, 110, 1705) and corroborate the interpretation, according to which the solvation of electrons is mainly governed by continuous solvent molecular motions.