RESUMEN
We consider the main aspects of detailed dynamics of the reactions of direct three-body ion-ion recombination Cs+ + X- + R â CsX + R (X- = F-, I- and R = Ar, Xe) for non-central encounters of the ions. The reactions are simulated by the quasiclassical trajectory method using diabatic semiempirical potential energy surfaces proposed previously. The recombination mechanisms are studied via visualization of randomly selected trajectories for each of the four systems. Comparison of trajectories for different systems with identical sets of initial conditions is carried out. For most of the presented trajectories, the ion encounter energy and the third body energy are equal to 1 eV. The characteristic function of recombination is defined, this function depends on 13 arguments including eight kinematic parameters. It is shown that the transfer of excess energy from the ion pair to the neutral atom can occur, in particular, via an encounter of the R atom with the Cs+ ion, via an encounter of the R atom with the X- ion, or via successive encounters of the R atom with both the ions, as well as via an "insertion" of the R atom between the ions.
RESUMEN
The direct three-body recombination reactions Cs+ + X- + R â CsX + R (X = F, I and R = Ar, Xe) are studied within the quasiclassical trajectory method using diabatic semiempirical potential energy surfaces, the encounters of the ions being non-central. The collision energies range between 1 and 10 eV (values typical for low temperature plasma), while the so-called delay parameter, which characterizes the delay in the arrival of the neutral atom R in relation to the time instant when the distance between the ions attains its minimum, is equal to 0 or 20%. The calculation results include the recombination excitation functions, the opacity functions, and the vibrational and rotational energy distributions of the recombination products. All the four reactions considered exhibit similar overall statistical dynamics, but each process has its own features. On the whole, for both the recombining pairs Cs+ + F- and Cs+ + I-, xenon is more effective than argon as an acceptor of excess energy from the ion pair. The rotational energy distributions of the salt molecules CsF and CsI are almost equilibrium, whereas the vibrational energy distributions are strongly non-equilibrium.
RESUMEN
Despite the ubiquity of recombination processes in nature and various technologies, presently little is known about the dynamics of these processes. This article reports on a quasi-classical trajectory study of the dynamics of the direct three-body recombination of Cs(+) and Br(-) ions in the presence of a Xe atom at energies of the ion encounter and that of the third body ranging from 0.2 to 10 eV. Several dynamical mechanisms of stabilization of the recombining ion pair have been found. Head-on ion encounters are characterized by two mechanisms of removing the energy from the recombining pair. In the case of nonzero impact parameters of ion encounters, the dynamics leading to the stabilization of the nascent CsBr molecule becomes much more complicated and three new mechanisms appear. They depend mainly on the energy of the ion encounter, on the energy of the collision of the ion pair with the third body, and on the impact parameter of the ion encounter and the impact parameter of the third body. The common feature of all the three mechanisms is the transfer of a fraction of the rotational energy of the recombining pair to the third body. This transfer plays a key role in the stabilization of the molecule. The dynamical peculiarities observed are expected to be common for the recombination of the charged and neutral particles.
RESUMEN
It is shown that in hard sphere (impulsive) collisions of atoms with diatomic molecules, complete conversion of the collision energy into the internal energy of the diatomic partner is possible for any number of impacts between the elastic balls representing the particles. The corresponding collision geometries and relations between the masses of the particles are described in detail.