${\mathrm{H}}^{+}-{\mathrm{H}}_2\mathrm{O}$ collisions are investigated using the time-dependent density-functional theory combined with the molecular dynamics method, in which the electrons are described quantum mechanically within the framework of time-dependent density-functional theory and the ionic cores are described classically by Newton's equations. The feedback between quantum electrons and classical ions is self-consistently coupled by Ehrenfest's method. The electron capture, electron loss, and ionization cross sections are obtained in the energy range of 1–1000 keV and excellent agreements are achieved with available experimental and theoretical data. The orientation effects of the ${\mathrm{H}}_2\mathrm{O}$ target are found to be significant in the collision processes, especially in low-energy collisions.

In this Letter, we propose a novel laser-induced inelastic diffraction (LIID) scheme based on the intense-field-driven atomic nonsequential double ionization (NSDI) process and demonstrate that, with this LIID approach, the doubly differential cross sections (DDCSs) of the target ions, e.g., ${\mathrm{Ar}}^{+}$ and ${\mathrm{Xe}}^{+}$, can be accurately extracted from the two-dimensional photoelectron momentum distributions in the NSDI process of the corresponding atoms. The extracted DDCSs exhibit a strong dependence on both the target and the laser intensity, in good agreement with calculated DDCSs from the scattering of free electrons. The LIID scheme may be extended to molecular systems and provides a promising approach for imaging of the gas-phase molecular dynamics induced by a strong laser field with unprecedented spatial and temporal resolution.

A combined experimental and theoretical study on single capture in 15–$50\mathrm{keV}/\mathrm{u}{\mathrm{C}}^{4+} +$ He collisions was performed. State-selective single-electron capture cross sections and projectile scattering angle distributions were obtained by using a reaction microscope. A comparison of the state-selective cross sections with theoretical calculations based on the two-active-electron semiclassical atomic-orbital close-coupling method showed an excellent agreement for the considered impact energies. For the angular differential cross sections, an overall agreement was also obtained between the present experimental and theoretical results. Simulations performed using an extended Fraunhofer-type diffraction model suggest that the undulatory structures observed at small scattering angles for capture to ${\mathrm{C}}^{3+}(1s^{2}2s$) and ${\mathrm{C}}^{3+}(1s^{2}2p_0$) can be interpreted as the diffraction pattern of the incident projectile de Broglie wave confined by an aperture defined as the region around the target where the considered capture process is likely. The strong competition between single-electron capture to ${\mathrm{C}}^{3+}(1s^{2}2p_0$) and ${\mathrm{C}}^{3+}(1s^{2}2p_1$) is also discussed to interpret the differences observed between their respective differential cross sections.

We investigate the intermolecular nonradiative charge transfer process in a double hydrogen-bonded formic acid (FA) dimer, initiated by electron-collision induced double ionization of one FA molecule. Through fragment ions and electron coincident momentum measurements and ab initio calculations, we obtain direct evidence that electron transfer from the neighboring FA molecule to fill one of the two vacancies occurs by a potential energy curve crossing of ${\mathrm{FA}}^{++}+\mathrm{FA}$ with ${\mathrm{FA}}^{+}+{\mathrm{FA}}^{+*}$ curves, forming an electronic excited state of dicationic dimers. This process causes the breaking of two hydrogen bonds and subsequently the cleavage of $\mathrm{C}─\mathrm{H}$ and $\mathrm{C}─\mathrm{O}$ covalent bonds in the dimers, which is expected to be a general phenomenon occurring in molecular complexes and can have important implications for radiation damage to biological matter.

Van der Waals clusters are weakly bound atomic/molecular systems and are an important medium for understanding micro-environmental chemical phenomena in bio-systems. The presence of neighboring atoms may open channels otherwise forbidden in isolated atoms/molecules. In hydrogen-bond clusters, proton transfer plays a crucial role, which involves mass and charge migration over large distances within the cluster and results in its fragmentation. Here we report an exotic transfer channel involving a heavy N⁺ ion observed in a doubly charged cluster produced by 1 MeV Ne⁸⁺ ions: (N₂Ar)²⁺→N⁺+NAr⁺. The neighboring Ar atom decreases the $${\mathrm{N}}_2^{2 + }$$N 2 2 + barrier height and width, resulting in significant shorter lifetimes of the metastable molecular ion state $${\mathrm{N}}_2^{2 + }$$N 2 2 + ( $${{\mathrm{X}}^{1}}{\Sigma _{{\mathrm{g}}}^{+}}$$X 1 Σ g + ). Consequently, the breakup of the covalent N⁺−N⁺ bond, the tunneling out of the N⁺ ion from the $${\mathrm{N}}_2^{2 + }$$N 2 2 + potential well, as well as the formation of an N−Ar⁺ bound system take place almost simultaneously, resulting in a Coulomb explosion of N⁺ and NAr⁺ ion pairs.

Coulomb-explosion imaging is a broadly employed technique to reconstruct the geometry of molecules from the direct multibody breakups of its ions. However, we reveal that this technique fails for a large class of systems, such as (${\mathrm{CO})}_2{}^{3+}$ and ${\mathrm{ArCO}}^{3+}$, since the events of the “direct breakup channel” are not the real direct breakups but the rapid sequential breakups with a short-lived and ultrafast-rotational fragment. Using Ar-CO as a prototype, we have investigated theoretically its Coulomb-explosion process. We find that due to the interfield between the metastable ${\mathrm{CO}}^{2+}$ and ${\mathrm{Ar}}^{+}$, ${\mathrm{ArCO}}^{3+}$ changes from its initial T shape into the more stable linear shape within 100 fs; such a rotation of ${\mathrm{CO}}^{2+}$ is hundreds of times faster than the field free case. Further, the advanced three-body surface hopping simulations indicate that the angle ${\angle }_{(\mathrm{Ar},\mathrm{CO})}$ has rotated from an initial ${95}^{\circ }$ to $110.6{}^{\circ }$ on average before the Coulomb explosion, which agrees well with the one (${115}^{\circ }$) detected by Gong et al. [ Phys. Rev. A 88, 013422 (2013)]. Furthermore, we point out that correct geometry of ArCO can be obtained from the three-body breakups with high kinetic-energy release ($>20$ eV).