Intermultiplet mixing in alkali atoms induced by collisions with diatomic molecules

Andreev, E.A.; Voronin, A. I.

doi:10.1016/0009-2614(69)85041-4

Cited by 23 publications

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“…The calculations were performed by using the so-called Muckerman-V potential surface, 3 and as will be seen, they yield results which agree with the experiments of Sparks etal. 2 These results represent the first successful computation of such phase-sensitive cross sections which can be compared with experiment. The physical content of the approximation we employ is based on the recognition that some nuclear motion degrees of freedom in molecular collisions are slower than others.…”

Section: (6)mentioning

confidence: 86%

“…This system is of great importance because Sparks etal. 2 have recently reported the first experimental determination of such state-resolved angular distributions for a reactive molecular collision. The system is of further importance for its role in the (F 2 ,H 2 ) laser system and the fact that it represents one of the main prototype reactions for studying energy disposal in reactive collisions.…”

Section: (6)mentioning

confidence: 98%

“…A\ { is the difference of the adiabatic eigenvalues of the two states that are coupled: By following the various sequences of crossings that can lead from the initial state ip x (j = i) to a final state ip 2 or ip 3 (7=2), we obtain the probability for changing fine-structure level: P = 2/) 1 (l~/> 1 ) + 2/> 2 (l-^2)(l«^1) 2 (17) AX X = Ae(a' + -fa+l) l/2 ,…”

Section: (6)mentioning

confidence: 99%

“…First, passage through an intermediate complex A + X~ is sometimes assumed to cause mixing of the fine-structure levels. 2 Second, if there is a near resonance between the fine-structure splitting A£ and a rotational transition of the molecule, the cross section may be enhanced. 3 " 6 In the present paper we present another mechanism, which has not previously been identified, and whose origin is essentially the simplest distinguishing feature of the alkali-molecule system, its reduced symmetry.…”

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Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Hickman¹

1981

Phys. Rev. Lett.

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Fine-structure transitions of alkali atoms induced by collisions with diatomic molecules are shown to be strongly influenced by a dynamical feature that is completely absent when the collision partner is a rare gas. The effect is a nonadiabatic coupling caused by the anisotropy of the molecule. Calculations for Rb(5 2 P 1 / 2 ) +H 2 and for Rb(5 2 P 1 / 2 ) +He are in good agreement with recent experiments and explain the dramatic difference between these two systems.PACS numbers: 34.10,+x, 34.50.-sThe collisional mixing of fine-structure levels of alkali atoms by various perturbers illustrates the interplay of several fundamental mechanisms. The process iswhere A is an alkali and X may be a rare gas or a diatomic molecule. In the former case, the scattering has been extensively investigated, and is well understood in terms of the analysis of Nikitin. 1 When the target is a molecule, experimental studies have generally shown that the cross section for process (1) becomes larger, sometimes by more than an order of magnitude.Previous theoretical analysis has generally invoked two mechanisms to explain such differences. First, passage through an intermediate complex A + X~ is sometimes assumed to cause mixing of the fine-structure levels. 2 Second, if there is a near resonance between the fine-structure splitting A£ and a rotational transition of the molecule, the cross section may be enhanced. 3 " 6 In the present paper we present another mechanism, which has not previously been identified, and whose origin is essentially the simplest distinguishing feature of the alkali-molecule system, its reduced symmetry. For collisions between an alkali atom and a rare gas, Nikitin 1 has shown how the electronic states of H e i and the fine-structure splitting Ae determine the adiabatic states and couplings of the full Hamiltonian H=H eX +H so (electronic plus spin orbit). The 2 and n states of H e i are degenerate asymptotically, and split as the internuclear distance R decreases. Corresponding adiabatic states A 2 U 1 / 2 and B 2 Z x / 2 of H are asymptotically separated by the fine-structure splitting A€. They are strongly coupled near the region where the splitting of the states Z and IT of H e i is equal to Ae. For rare-gas targets, there are of course two II electronic states, which are degenerate. For molecular targets, the nomenclature changes somewhat, but effectively the degeneracy of the two II states is lifted by the anisotropy of the molecule. Consequently the adiabatic states of H e i+H %Q experience an additional coupling near the region where the splitting of the two II-like states of i/ e i is equal to Ae.I will illustrate this effect by the following analysis of the collision. Let the system alkali plus diatomic molecule be described by an electronic Hamiltonian H el whose matrix elements in the basis of the alkali orbitals np xy np y> and np z are H xx , H xyy etc. This Hamiltonian has been discussed by Rebentrost and Lester. 4 The matrix elements of H el are functions of R and 0, which define in the usual ...

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Section: (6)mentioning

confidence: 86%

Section: (6)mentioning

confidence: 98%

Section: (6)mentioning

confidence: 99%

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confidence: 99%

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Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Hickman¹

1981

Phys. Rev. Lett.

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“…If this interpretation seems to account for the measured z3F40 z3F fine-structure transition cross section (tr= a4r), differences are observed for the two other transitions when the colliding partner is N2 instead of Ar, despite the relatively large experimental uncertainties: assumed to cause mixing of the fine-structure levels 39 or additional non-adiabatic coupling caused by the anisotropy of the molecule a6'37 might be invoked to explain these differences. However, we may expect that the effects of such phenomena are of the same order for the three "J-changing" processes under study, while measurements seem to indicate a correlation between the differences (ri 2 ?ri r) and the corresponding fine-structure energy splittings AE.…”

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confidence: 99%

Change In Total Angular Momentum Within The Z³F⁰ Titanium Excited StateInduced By Collisions With Hydrogen And Nitrogen Molecules

et al. 1988

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Collisions that produce a change in the total angular-momentum and quenching processes involving the triplet z3F titanium excited level and diatomic molecules have been studied by laser perturbation and time-resolved spectroscopy. The thermally averaged total angular-momentum changing cross sections (za-z3F)inunitsof10-16cm2are'042=3.2+l, 1.4+0.5; 743= 13.3+2, 6.8+1; 032 =19.0 _.+ 2, 7.2 _+ 1, respectively, for nitrogen and hydrogen colliding partners.Large quenching cross sections are obtained, as OQ N2 53 7, and r2 38 _+ 4 in units of 10 -16 cm2. These results are discussed in relation with p'evious measurements dealing with titanium--noble-gas collisions, and with available published results.

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Sensitized Fluorescence and Quenching

Krause

1975

Advances in Chemical Physics

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Intermultiplet mixing in alkali atoms induced by collisions with diatomic molecules

Cited by 23 publications

References 8 publications

Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Change In Total Angular Momentum Within The Z³F⁰ Titanium Excited StateInduced By Collisions With Hydrogen And Nitrogen Molecules

Sensitized Fluorescence and Quenching

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Intermultiplet mixing in alkali atoms induced by collisions with diatomic molecules

Cited by 23 publications

References 8 publications

Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Nonadiabatic Coupling in Fine-Structure Transitions of Alkali Atoms Induced by Diatomic Molecules

Change In Total Angular Momentum Within The Z3F0 Titanium Excited StateInduced By Collisions With Hydrogen And Nitrogen Molecules

Sensitized Fluorescence and Quenching

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Change In Total Angular Momentum Within The Z³F⁰ Titanium Excited StateInduced By Collisions With Hydrogen And Nitrogen Molecules