Observation of enhanced rate coefficients in the H2++H2→H3++H reaction at low collision energies

Abstract

The energy dependence of the rate coefficient of the H + 2 + H 2 → H + 3 + H reaction has been

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

“…[18] Opposite trends in the rate constants can alternatively be foreseen when long-range interaction potentialsr eorient the reacting couple into preferred configurations that are also the most facile for reaction. [8] In conclusion, our investigation demonstrates that, forc harge-transfer processes, rate constants obtained from simple capture models, which usually exhibit a negative temperature-dependent trend, due to an increased probability of capturea td ecreasing collisione nergies, may lead to results at odds with experimentalf indings and ad etailed dynamical treatment is necessary for ac orrect evaluation of the relevant observables.…”

“…[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]). …”

Experimental progress in positronium laser physics

“…This work allowed control over the translational motion of hydrogenic [457] and non-hydrogenic [458] atoms, as well as the realization of a wide range of atom optics elements, including mirrors [459], lenses [457], deflectors [460,461], decelerators and traps [436,[462][463][464][465][466]. These advances have been employed for a various studies, including the effects of blackbody induced transitions and photoionization of Rydberg states [463,467], m-changing dipole-dipole interactions in gases of polar Rydberg atoms and their effects on Rydberg state lifetimes [468], the preparation of long-lived high-|m| (i.e., |m| ≥ 3) Rydberg states of H 2 [469,470], and new methods to study ion-molecule reactions at low temperatures [471,472].…”

Preparation of circular Rydberg states in helium with n≥70 using a modified version of the crossed-fields method

“…In these settings new opportunities for imaging boundstate electron probability density distributions are also expected [48]. Circular Rydberg states with high values of n are also of interest in studies of ion-neutral reactions at low translational temperatures where the Rydberg electron can be exploited to shield the reaction center from stray electric fields and hence ensure that low collision energies are maintained throughout the reaction process [49,50]. In the case of the H + 2 +H 2 reaction, studied at low temperature through collisions of Rydberg H 2 with ground-state H 2 [49], the method described here may be applied to the preparation of circular Rydberg states of H 2 to open new opportunities for investigating, and if necessary minimizing, the contributions from the Rydberg electron to the reaction dynamics.…”