Oxidation reactions by radicals constitute a very important class of chemical reactions in solution. Radiation Chemistry methods allow producing, in a controlled way, very reactive oxidizing radicals, such as OH^•, CO₃^•–, NO₃^•, SO₄^•–, and N₃^•. Although the radical cation of water, H₂O^•+, with a very short lifetime (shorter than 1 ps) is the precursor of these radicals in aqueous solutions, its chemistry is usually known to be limited to the reaction of proton transfer by forming OH^• radical. Herein, we stress situations where H₂O^•+ undergoes electron transfer reaction in competition with proton transfer.

Where does the reaction between prehydrated electrons and nucleotides lead to?

The reactivity of ethylene carbonate (EC) and of a EC/diethyl carbonate (DEC) mixture was studied under ionizing radiation to mimic the aging phenomena that occur in lithium‐ion batteries. Picosecond‐pulse radiolysis experiments showed that the attachment of the electron to the EC molecule is ultrafast (k(e⁻_EC+EC)=1.3×10⁹ L mol⁻¹ s⁻¹ at 46 °C). This reaction rate is accelerated by a factor of 5.7 compared with the electron attachment to propylene carbonate, which implies that the presence of the methyl group significantly slows the reaction. In a 50:50 EC/DEC mixture, just after the electron pulse the electron is solvated by a mixture of EC and DEC molecules, but its fast decay is attributed exclusively to electron attachment to the EC molecule. Stable products detected after steady‐state irradiation were mainly H₂, CH₄, CO, and CO₂. The evolution of the radiolytic yields with the EC fraction shows that H₂ and CH₄ did not exhibit linear behavior, whereas CO and CO₂ did. Indeed, H₂ and CH₄ mainly arise from the excited state of DEC, the formation of which is significantly affected by the evolution of the dielectric constant of the mixture and by the electron attachment to EC. CO formation is mainly due to the reactivity of the EC molecule, which is not affected in the mixture, as proven by pulse‐radiolysis experiments.

The ionizing radiation in aqueous solutions of gold nanoparticles, stabilized by electrostatic non-covalent intermolecular forces and steric interactions, with antimicrobial compounds, are investigated with picosecond pulse radiolysis techniques. Upon pulse radiolysis of an aqueous solution containing very low concentrations of gold nanoparticles with naked surfaces available in water (not obstructed by chemical bonds), a change to Cerenkov spectrum over a large range of wavelengths are observed and pre-solvated electrons are captured by gold nanoparticles exclusively (not by ionic liquid surfactants used to stabilize the nanoparticles). The solvated electrons are also found to decay rapidly compared with the decay kinetics in water. These very fast reactions with electrons in water could provide an enhanced oxidizing zone around gold nanoparticles and this could be the reason for radio sensitizing behavior of gold nanoparticles in radiation therapy.

We explore the use of room-temperature ionic liquids (ILs) as Raman wavelength converters. ILs provide an engineerable framework to design suitable liquids for wavelength conversion over a broad spectral range, through careful selection of the molecular structures of the IL anions and cations so that specific characteristics can be obtained, such as a desirable Raman shift, low Brillouin scattering, and good optical transmission in the pump and Stokes wavelengths. Applying such criteria, we demonstrate that 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA) is an effective medium for conversion of 532-nm pulses from a Q-switched $\mathrm{Nd}:$YAG laser to 603 nm. This corresponds to an approximate 2200 ${\mathrm{cm}}^{-1}$ shift, which can be used to generate mid-infrared radiation through subsequent difference frequency generation for optical pumping of ${\mathrm{CO}}_2$ lasers. Threefold-higher Raman conversion efficiency is obtained in EMIM DCA compared with water under identical conditions in a proof-of-principle single-pass conversion setup, resulting in an efficient generation of multimillijoule, <6 ns duration, high-quality orange laser pulses in a wavelength region that is difficult to access at high energies. Consequently, we examine ILs representing two other classes of Raman-active functional groups and obtain conversion up to the fifth-order Stokes shift and first anti-Stokes shift. Through the tunable selection of their components and their useful dynamical properties, ILs provide a platform for efficient, simple, and alignment-tolerant high-energy Raman shifting with numerous industrial and technological applications.