The deposition of large amounts of energy in a molecule by XUV/X-ray photon absorption or fast-ion collision, triggers a set of complex ultrafast electronic and nuclear dynamics that allow a deep understanding and control of chemical reactivity. This themed issue showcases the research performed in the understanding, monitoring and control of these processes.

We consider the process of collision between a hard photon and a soft photon producing an electron-positron pair, under the assumption that the kinematics be described according to the κ-deformation of the D=4 Poincaré algebra. We emphasize the relevance of this analysis for the understanding of the puzzling observations of multi-TeV photons from Markarian 501. We find a significant effect of t...

Following a recent proposal by S. B. Zheng and G. C. Guo [Phys. Rev. Lett. 85, 2392 (2000)], we report an experiment in which two Rydberg atoms crossing a nonresonant cavity are entangled by coherent energy exchange. The process, mediated by the virtual emission and absorption of a microwave photon, is characterized by a collision mixing angle 4 orders of magnitude larger than for atoms collidi...

We apply the Equivalent Photon Approximation to calculate cross sections for the simultaneous excitation of two heavy ions in relativistic collisions. We study especially the excitation of two nuclei to a 1-state and show that the equations are symmetric with respect to both ions. We also examine the limit in which the excitation energy of one of the nuclei goes to zero, which gives the elastic...

Direct photons are a powerful probe to study the properties of the unique matter created in ultrarelativistic heavy-ion collisions. They carry information on the various stages of a heavy-ion collision. At different transverse momenta (pT), different production processes dominate the direct photon yield in heavy-ion collisions. Photons at high pT can be used to study initial hard scattering pro...

We discuss laser-dressed dipolar and van der Waals interactions between atoms and polar molecules, so that a cold atomic gas with laser admixed Rydberg levels acts as a designed reservoir for both elastic and inelastic collisional processes. The elastic scattering channel is characterized by large elastic scattering cross sections and repulsive shields to protect from close encounter collisions...

Experimental and theoretical studies are presented on the reactivity of methanimine aminomethylene cations with ethene. Selective isomer generation is performed via dissociative photoionization suitable neutral precursors reactive cross sections branching ratios measured as a function photon collision energies.

The emission of circularly polarized photons during the scattering of fast spin-polarized electrons from heavy nuclei is studied within the Dirac–Sommerfeld-Maue approach. Predictions are made for the dependence of the polarization correlations C32 and C12 on collision energy, photon energy and nuclear charge. A comparison with pilot measurements of the transmission asymmetry, sensitive to C32,...

Various 2-particle direct photon-hadron correlation yields in p + p and Au + Au collisions at √ sNN = 200 GeV are presented. The per-trigger yield of direct photon hadron pairs from direct-photon-jet correlations is obtained by a statistical subtraction of the decay photon pairs from inclusive photon-hadron sample. The decay photon pertrigger yields are estimated from the measured π-hadron by m...