A nomenclature for Λ-doublet levels in rotating linear molecules

Alexander, M. H.; Andresen, Peter L.; Bacis, R.; Bersohn, R.; Comes, F. J.; Dagdigian, Paul J.; Dixon, Ronald; Field, Robert W.; Flynn, George W.; Gericke, K.‐H.; Grant, Edward R.; Howard, Brian J.; Huber, J. Robert; King, David S.; Kinsey, James L.; Kleinermanns, Karl; Kuchitsu, K.; Luntz, A. C.; McCaffery, A. J.; Pouilly, Brigitte; Reisler, H.; Rosenwaks, Salman; Rothe, Erhard W.; Shapiro, Moshe; Simons, J. P.; Vasudev, R.; Wiesenfeld, J. R.; Wittig, C.; Zare, Richard N.

doi:10.1063/1.455121

Cited by 222 publications

(44 citation statements)

References 73 publications

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“…In turn, Ω′ is the projection of j ′ along the SF Z axis (usually m ′ is used to designate the projection of j ′ onto the SF axis, but in the present case, as k ′ is taken as Z , it corresponds to the helicity, which is commonly designated by Ω′). As discussed in refs 10, 13, 14, with this choice of frames, for Ω′=0 and j ′≫1, j ′ lies along u (the y axis) and xz is the rotation plane. For Ω′= j ′ and j ′≫1, j ′ is along the x axis, which in this case is along − Z and the rotation plane is yz .…”

Section: Methodsmentioning

confidence: 99%

“…Recent experiments by Minton, McKendrick and coworkers56 have determined the OD( X 2 Π) state-to-state Λ-doublet population ratios for O( 3 P)+D 2 collisions. Regardless of the collision energy and final vibrational state, they consistently found a significantly larger population of the Π( A ′) Λ-doublet state compared with the Π( A ′′) one, where the labelling of the states refers to the location of the singly occupied orbital in the rotation plane of the diatom, Π( A ′), or perpendicular to it, Π( A ′′), in the limit of high products rotational states j ′ (refs 14, 16, 18). This result seems to contradict the theoretical results, which would predict a preference for Π( A ′′) under the assumption that collision on two concurrent PESs of symmetry 3 A ′ and 3 A ′′ would only form Π( A ′) and Π( A ′′) Λ-doublet states, respectively.…”

mentioning

confidence: 88%

“…In spite of the tiny energy difference between the Λ-doublet pair of states, a clear preference towards one of them is observed in many chemical processes123456, including inelastic and reactive collisions, and molecular photodissociation, and has even been postulated as the origin of OH astronomical masers78. As pointed out by several authors891011121314151617, the Λ-doublet population acts as a fingerprint to unravel the symmetries of the surfaces involved in the process, such that the propensity for one of the manifolds reflects the competing reactivity on concurrent PESs and addresses the question of where the electrons go when the reaction takes place1517. However, a general, clear-cut relationship between them has not yet been demonstrated.…”

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Product lambda-doublet ratios as an imprint of chemical reaction mechanism

et al. 2016

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In the last decade, the development of theoretical methods has allowed chemists to reproduce and explain almost all of the experimental data associated with elementary atom plus diatom collisions. However, there are still a few examples where theory cannot account yet for experimental results. This is the case for the preferential population of one of the Λ-doublet states produced by chemical reactions. In particular, recent measurements of the OD(2Π) product of the O(3P)+D2 reaction have shown a clear preference for the Π(A′) Λ-doublet states, in apparent contradiction with ab initio calculations, which predict a larger reactivity on the A′′ potential energy surface. Here we present a method to calculate the Λ-doublet ratio when concurrent potential energy surfaces participate in the reaction. It accounts for the experimental Λ-doublet populations via explicit consideration of the stereodynamics of the process. Furthermore, our results demonstrate that the propensity of the Π(A′) state is a consequence of the different mechanisms of the reaction on the two concurrent potential energy surfaces

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Section: Methodsmentioning

confidence: 99%

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Product lambda-doublet ratios as an imprint of chemical reaction mechanism

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“…In the rotating molecule the interaction between the electronic angular momentum and the rotational angular momentum splits every spin-orbit state into two A components (57), denoted as n(A') and n(A") according to ref. 58 reflection symmetry with respect to the plane of rotation. In this case the n(A') A-doublet states can be characterized by the .rr molecular orbital lobes being located in the plane of rotation, while in case of the n(A") A-doublet states the -I T molecular orbital lobes are oriented perpendicular to the plane of rotation.…”

Section: A H + D20mentioning

confidence: 99%

Reaction dynamics studies of a simple tetraatomic system: AA + BA ↔ A + ABA

Koppe¹,

Thomas²,

Naik³

et al. 1994

Can. J. Chem.

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. 72, 615 (1994).We have studied the reaction of translationally excited hydroxyl radicals with molecular hydrogen at different center-of-mass energies. H/D atoms produced in the reaction have been detected under single collision conditions by means of vacuum ultraviolet laser-induced fluorescence at the Lyman-a transition. By calibrating the H/D signals from the reaction against H atom signals from the H2S and HC1 photolysis, respectively, the following absolute reactive cross sections were determined: OH + H2 + H + H20: uR(O. At different center-of-mass collision energies nascent population distributions of the OD product fine-structure components were determined. It has been found that at all collision energies OD radicals are produced exclusively in their vibrational ground state, with only a small amount of the total available energy appearing in the rotational degree of freedom. A comparison of the dependence of the reaction cross section on the translational energy shows that relative reagent translation is more effective to promote reactivity in the reaction OH + H2 and OH + D2 than in the reaction H + D20. This, together with a preferential population of the symmetric 2 n (~' ) A-doublet state (with the unpaired .ir orbital lying in the plane of rotation) at high OD rotational quantum numbers, suggests that the reaction H + D 2 0 + OD + HD proceeds through a planar transition state via a direct mechanism, where the OD moiety acts as a spectator, and where the reaction barrier is located at a "later" position of the reaction coordinate. cas, pour dCtecter les radicaux OD produits dans des conditions de collision unique, avec une rksolution de I'ktat quantique, on a fait appel i la fluorescence induite au laser. En calibrant les signaux OD de la rCaction I'aide de signaux OH obtenus par photolyse de H202, on a mesurk les sections droites absolues de la rCaction H + D 2 0 + OD + HD : uR(l ,5 eV) = (0,07 t 0,04) A2, uR(1,8 eV) = (0,10 t 0,03) A2 et uR(2,2 eV) = (0,11 2 0,03) A2. On a determink, 2 diverses Cnergies de collision du centre de masse, les distributions de population naissante de composantes de la structure fine du produit OD. On a trouvk que, pour toutes les Cnergies de collision, les radicaux OD ne sont produits que dans leur ktat vibrationnel fondamental; seule une faible partie de l'knergie totale disponible appardt dans le degrC de libert6 rotationnel. Une comparaison de la dkpendance de la section droite de la rkaction sur l'knergie de translation montre que la translation relative du rkactif est plus efficace pour promouvoir la rdactivitk dans les rkactions OH + H2 et OH + D2 que dans la reaction H + D20. Ce rksultat, pris avec le fait que la population de I'ktat doublet symktrique-A, 2 n (~' ) (comportant une orbitale TI non appariCe se trouvant dans le plan de rotation), est prCfCrke pour les nombres quantiques klevks de OD, suggkre que la r6action H + D 2 0 + OH + HD se produit par un mkcanisme direct impliquant un ktat de transition plan alors que la portion OD agit comme spectateur et...

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“…The parity eigenstates with = þ1 and À1 are, respectively, labelled c and d [11], or A 0 and A 00 [12]. …”

Section: Hund's Case Bmentioning

confidence: 99%