Proton migration in hydrocarbons induced by slow highly charged ion impact

Abstract

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.

Dissociative ionization and Coulomb explosion of CH4 in two-color asymmetric intense laser fields

“…13(a) shows a broad distribution peaked at 5.2 eV, which is in good agreement with that observed in the previous study. 60 The Auger-electron–photoion coincidence spectroscopy 37 provided a secure assignment that the fragmentation proceeds from the 1 T 2 state of CH 4 2+ in the (1 t 2 ) −2 configuration, which was confirmed later by the electron impact study. 38…”

“…A possible scenario will be discussed in the next subsection. 38,57,58 and ion 43,60 impact studies on methane. The KER spectrum in Fig.…”

“…3). Coulomb explosion from these dicationic states was studied previously by EUV 35,36 and soft-X ray 33,37 single-photon ionization as well as by electron 38,57,58 and ion 43,59,60,61 impact ionization. The Auger electron-ion coincidence spectroscopy 37 showed that the Coulomb explosion CH component on the higher energy side forming a long tail extending up to B10 eV.…”

Isomerization Dynamics in the Symmetric and Asymmetric Fragmentation of Ethane Dications

“…Three-dimensional momentum vectors of the recoil ions were retrieved by the TOF and position data, and thus, the KER of corresponding dissociation channel can be obtained. For the HCI collision experiment, an ion beam of 3 keV/u Ar 8+ produced by an electron cyclotron resonance ion source (ECRIS) collided with an ethane cold target in a high-vacuum interaction chamber. The extraction field was 50 V/cm.…”

“…Hydrogen or proton migration in intramolecular or intermolecular reactions, hailed as “the most general and important reaction in chemistry”, plays a vital role in the evolution of fragmentation dynamics of organic molecules. In this context the acetylene–vinylidene isomerization in the dissociation of the ionic acetylene molecule has been extensively studied as a prototype to retrieve information on proton migration dynamics. − …”