Effect of rovibrational coupling on the dynamics of ionic systems: the Kr-O₂⁺case

Abstract

Various quantum decoupling and semiclassical methods are used to calculate cross sections for rotational and rovibrational transitions in O2+ colliding with Kr. A general analysis of time scales for rotational and vibrational excitations and of coupling strengths for the corresponding potentials is used to review the standard decoupling methods that treat separately vibrations and rotations in atom-molecule collisions. When such decoupling is applied to strongly interacting ionic systems and to heavy particles, it is found to fail rather dramatically and to be brought back to reliable values only when fully coupled rovibrational equations are used to treat the dynamics.

Interaction and dynamics of collisional energy transfers in simple ion-molecule systems

“…For (near) collinear approaches the opacities exhibit oscillatory patterns which become more marked at low-l values, while for perpendicular approaches they become more monotonic in nature. It is interesting to note here that a recent VCC-RIOS study [32,33] for the vibrational excitations in H>-HF collisions also revealed oscillations in the opacity plots and related to characteristic variations in the potential which, however, turned out to be more pronounced for that system than in the present situation.…”

“…Strictly speaking, for such a decoupling procedure to work the interaction time must be short when compared to the rotational period. Such decouplings, and their possible failures because of strong dynamical mixing between rotational and vibrational excitation channels in the cases of ion-molecule interactions with heavy ions, have been extensively discussed recently in our group [32]. One therefore needs a certain amount of caution in applying here the IOS treatment, particularly with fast rotors like H .…”

Vibrational relaxation in the NO+–He collision system: Implication of the Gislason–Ferguson model

“…Very recently this system was a new subject of detailed classical mechanical 26,27 and quantummechanical 28,29 studies.…”

“…However, the rigorous 3D quantummechanical calculations are still too difficult and expensive to perform for many practical applications. For instance, in recent publications, 28,29 using fairly rigorous quantummechanical methods, only the values of some selected reaction probabilities, but not the ones of the corresponding cross sections could be calculated within reasonable computational time. It appears also, that for certain ionic potentials and mass combinations even the conventional approximate versions of the quantum-mechanical method ͑i.e., VCC-RIOSA͒ can fail completely at low energies.…”

Ab initio investigation of the lowest X˜2A″ and A˜Papakondylis1 2010Chemical Physics Letters2030View full textAdd to dashboardCite

“…Kr + + O 2 and the photodissociation of the KrO þ 2 complex [4], while others investigate the vibrational quenching [5,6] of O þ 2 by Kr. Many theoretical studies [7][8][9][10][11][12][13][14] have been carried out in order to elucidate the mechanisms of the O þ 2 vibrational relaxation through collisions with Kr atoms. Of course, an accurate potential energy surface describing the KrÁ Á ÁO þ 2 interaction is a prerequisite for such theoretical studies.…”