Collisional excitation of CO: a study of the wigner spin rule

Lee, A.R.; Enos, C.S.; Brenton, A.G.

doi:10.1016/0168-1176(91)85005-7

Cited by 19 publications

(1 citation statement)

References 6 publications

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“…Since the early days of quantum mechanics a central question in reaction dynamics is whether composite spins are conserved. Wigner's spinconservation rule, e.g., states that the total electronic spin has a propensity to be conserved [3][4][5]. The recent progress in the quantum state-resolved preparation and detection of ultracold atoms and molecules has now made it possible to experimentally explore spin conservation rules that also involve nuclear spins.…”

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confidence: 99%

Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms

Haze,

D'Incao,

Dorer

et al. 2021

Preprint

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We explore the physical origin and the general validity of a propensity rule for the conservation of the hyperfine spin state in three-body recombination. This rule was recently discovered for the special case of 87 Rb with its nearly equal singlet and triplet scattering lengths. Here, we test the propensity rule for 85 Rb for which the scattering properties are very different from 87 Rb. The Rb 2 molecular product distribution is mapped out in a state-to-state fashion using REMPI detection schemes which fully cover all possible molecular spin states. Interestingly, for the experimentally investigated range of binding energies from zero to ∼ 13 GHz × h we observe that the spin-conservation propensity rule also holds for 85 Rb. From these observations and a theoretical analysis we derive an understanding for the conservation of the hyperfine spin state. We identify several criteria to judge whether the propensity rule will also hold for other elements and collision channels.

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mentioning

confidence: 99%

Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms

Haze,

D'Incao,

Dorer

et al. 2021

Preprint

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Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

Enos

Lee

Brenton

1991

Org. Mass Spectrom.

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Studies of internal energy changes between the partners in ion-molecule collisions can be facilitated by highresolution translational energy spectroscopy. Collisions of keV H', N + and 0' on molecular nitrogen and oxygen have shown that for 30 reaction channels all are consistent with spin conservation, which has not been generally acknowledged in previous studies. Estimations of the fractional metastable composition in each ion beam have also been made.

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Translational energy spectroscopy. I. Theory and practical considerations

Enos

Brenton

1993

Rapid Comm Mass Spectrometry

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Non-dissociative collision processes are classified and the accepted notation is given. The basic kinematics of binary collisions are derived and practical considerations based on Massey's adiabatic criterion together with the effects of pressure and temperature are discussed. A general description of instrumental developments and the performance achieved are given and the predictions of the Wigner spin conservation rule as regards the spectroscopic states of the products are summarized.Translational energy spectroscopy enables details of collisional processes to be investigated. This first part of the paper devoted to this technique attempts to set out the background necessary to understand binary elastic and inelastic non-dissociative collisions and how information concerning transfer of kinetic and internal energy can be gleaned using recently developed techniques. The resolution achieved by modern instruments is discussed and the Wigner spin-conservation rule is detailed. The second part of the paper will give detailed experimental results from the authors' laboratory and discuss tests of Wigner's hypothesis. CLASSIFICATION OF NON-DISSOCIATIVE COLLISIONAL PROCESSESA collision between two independent bodies will produce physical changes which can include changes in deflection angle, changes in kinetic or internal potential energies, chemical changes and the gain or loss of electrons. Reactive collisions which result in chemical changes and which are only of significance at low impact energies are not dealt with. All non-reactive collisions are either classed as being elastic or inelastic. Elastic collisions only involve the exchange of kinetic energy and hence there is no change in the internal energy states of either collision partner. In contrast, inelastic collisions involve the interconversion of kinetic and internal energy, resulting in overall changes to the internal energy states of the collision partners. Inelastic collisions, during which internal energy is converted into kinetic energy are more commonly referred to as superelastic collisions. NotationHasted' devised a useful notation method for the description of two-body inelastic collisional processes. The symbols used by Hasted to represent the collidants are listed in Table 1. In this notation, the charge and state of excitation of both collidants before and after the binary collision are specified explicitly. For example, a process in which a projectile of charge A collides with a target of charge B resulting in the production of species of charges P and Q is abbreviated using this

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Collisional excitation of CO: a study of the wigner spin rule

Cited by 19 publications

References 6 publications

Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms

Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms

Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

Translational energy spectroscopy. I. Theory and practical considerations

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