On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation

To understand the yield and patterns of damage in aqueous condensed matter, including biological systems, it is essential to identify the initial products subsequent to the interaction of high energy radiation with liquid water. Until now, the observation of several fast reactions induced by energetic particles in water was not possible on their characteristic timescales. Therefore, some of the reaction intermediates involved, particularly those that require nuclear motion, were not considered when describing radiation chemistry. Here, through a combined experimental and theoretical study, we elucidate the ultrafast proton dynamics in the first few femtoseconds after X ray core level ionization of liquid water. We show through isotope analysis of the Auger spectra that proton transfer dynamics occur on the same timescale as electron autoionization. Proton transfer leads to the formation of a Zundel type intermediate [HO H H2O] , which further ionizes to form a so far unnoticed type of dicationic charge separated species with high internal energy. We call the process proton transfer mediated charge separatio

Transforming Anion Instability into Stability Contrasting Photoionization of Three Protonation Forms of the Phosphate Ion upon Moving into Water

We use photoelectron emission spectroscopy with vacuum microjet technique and quantum chemistry calculations to investigate electronic structure and stability of aqueous phosphate anions. On the basis of the measured photoelectron spectra of sodium phosphates at different pH, we report the lowest vertical ionization energies of monobasic 9.5 eV , dibasic 8.9 eV , and tribasic 8.4 eV anions. Electron binding energies were in tandem modeled with ab initio methods, using a mixed dielectric solvation model together with up to 64 explicitly solvating water molecules. We demonstrate that two solvation layers of explicit water molecules are needed to obtain converged values of vertical ionization energies VIEs within this mixed solvation model, leading to very good agreement with experiment. We also show that the highly charged PO43 anion, which is electronically unstable in the gas phase, gains the electronic stability with about 16 water molecules, while only 2 3 water molecules are sufficient to stabilize the doubly charged phosphate anion. We also investigate the effect of ion pairing on the vertical ionization energy. In contrast to protonation leading to a formation of covalent O H bond , sodiation leading to an anion Na ion pair has only a weak effect on the electron binding energ

Considerable matrix shift in the electronic transitions of helium-solvated cesium dimer cation Cs2Hen+

We investigate the photodissociation of helium-solvated cesium dimer cations using action spectroscopy and quantum chemical calculations. The spectrum of Cs2He+ shows three distinct absorption bands into both bound and dissociative states. Upon solvation with further helium atoms, considerable shifts of the absorption bands are observed, exceeding 0.1 eV (850 cm-1) already for Cs2He10+, along with significant broadening. The shifts are highly sensitive to the character of the excited state. Our calculations show that helium atoms adsorb on the ends of Cs2+. The shifts are particularly pronounced if the excited state orbitals extend to the area occupied by the helium atoms. In this case, Pauli repulsion leads to a deformation of the excited state orbitals, resulting in the observed blue shift of the transition. Since the position of the weakly bound helium atoms is ill defined, Pauli repulsion also explains the broadening.(VLID)4795191Version of recor

Infrared spectroscopy of hydrated bisulfate anion clusters: Hso4-(h2o)(1-16)

Contains fulltext : 98890.pdf (publisher's version ) (Closed access