Dynamics of proton migration and dissociation in core-excited ethyne probed by multiple ion momentum imaging

Proton migration in hydrocarbons induced by slow highly charged ion impact

Different from most of the previous studies using light or photons, we use highly charged ions as projectiles to activate proton migration in the smallest saturated and unsaturated hydrocarbon molecules, i.e., CH₄ and C₂H₂. The H₃ ⁺ formation channel (H₃ ⁺ + CH⁺) and isomerization channel (C⁺ + CH₂ ⁺), serving as indicators of proton migration, are observed in the fragmentation of CH₄ and C₂H₂ dications. Corresponding kinematical information, i.e., kinetic energy release, is for the first time obtained in the collisions with highly charged ions. In particular, for the C⁺ + CH₂ ⁺ channel, a new pathway is identified, which is tentatively attributed to the isomerization on high-lying states of acetylene dication. The kinetic energy release spectra for other two-body breakup channels are also determined and precursor dication states could thus be identified.

Molecular dynamics of NH3 induced by core-electron excitation

Complex nuclear dynamics in the N1s⁻¹4a11 state disentangled and understood by probing the 4a₁ PES via photon energy detuning.

Dissociation pathways in the cysteine dication after site-selective core ionization

A photoelectron-ion-ion coincidence experiment has been carried out on the amino acid molecule cysteine after core-ionization of the O 1s, N 1s, C 1s, and S 2p orbitals. A number of different dissociation channels have been identified. Some of them show strong site-selective dependence that can be attributed to a combination of nuclear motion in the core-ionized state and Auger processes that populate different final electronic states in the dication.