Imaging state-to-state reactive scattering in the Ar+ + H2 charge transfer reaction

Abstract

The charge transfer reaction of Ar with H and D has been investigated in an experiment combining crossed beams with three-dimensional velocity map imaging. Angle-differential cross sections for two collision energies have been obtained for both neutral species. We find that the product ions are highly internally excited. In the reaction with H, the spin-orbit excited Ar state's coupling to the "resonant" vibrationally excited product H (υ = 2) dominates for both investigated energies, in line with previous investigations. The observed angular distributions, however, show significantly less back-scattering than was found previously. Furthermore, we discovered that the product ions are highly rotationally excited. In the case of Ar reacting with D, the energetically closest lying vibrational levels are not strictly preferred and higher-lying vibrational levels are also populated. For both species, the backward-scattered products show higher internal excitation.

Charge transfer dynamics in Ar+ + CO

“…Since the two states CO + (X 2 + , ν = 6 i ,7 ii ) are the closest accessible ones to the reactant Ar + in its two spin-orbital states, this suggests a resonant charge transfer as the dominant mechanism [44]. This is similar to the reaction of Ar + with H 2 [9], however no indirect part is observed there. As can be seen in the comparison of the 0-10 • to the 30-40 • cut ( Figure 2(c,g)), higher scattering angles lead to higher internal excitation, which was also observed for Ar + +N 2 [7].…”

“…They represent a simple reaction that occurs through the exchange of an electron, but can exhibit quite intricate mechanisms [1,2]. This becomes evident in a multitude of CONTACT R. Wester roland.wester@uibk.ac.at previously studied charge transfer reactions [3][4][5][6][7][8][9][10][11][12][13]. One particularly interesting one is the reaction of Ar + ( 2 P J ) with the diatomic CO molecule; a reaction that has been studied for almost six decades .…”

“…We have obtained differential cross sections for the title reaction by using our ion-molecule crossed beam velocity map imaging setup at the two collision energies 0.55 and 0.74 eV, bridging the gap between earlier studies at thermal and the recent study at higher collision energies. This experimental method has proven to be capable of disentangling the internal product energy distribution in numerous charge transfer reactions [3][4][5][6][7][8][9][10][11][12][13].…”

The Selective Role of Long‐Range Forces in the Stereodynamics of Ion–Molecule Reactions: The He++Methyl Formate Case From Guided‐Ion‐Beam Experiments

“…[24] Ion-molecule reactions that have been studied in such detail are still limited, relativelys parse andi nm ostc ases confined to simple systemsw ith as mall number of atoms (for recente xamples, see refs. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]). …”

Imaging the dynamics of ion–molecule reactions

“…1) and up to 8h at a collision energy of E coll = 0.28 eV. 55 The reactant H 2 beam was generated by supersonic expansion and molecules can be considered to be mostly in the rovibrational ground state at the experimental conditions. Given the single collision conditions in the experiment, more than one rotational quantum has to be transferred into rotational excitation in a single reactive collision.…”