TY  - JOUR
A1  - Bartlett, Nate C. -M.
A1  - Jankunas, Justin
A1  - Goswami, Tapas
A1  - Zare, Richard N.
A1  - Bouakline, Foudhil
A1  - Althorpe, Stuart C.
T1  - Differential cross sections for H + D-2 -> HD(v '=2, j '=0,3,6,9) + D at center-of-mass collision energies of 1.25, 1.61, and 1.97 eV
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - We have measured differential cross sections (DCSs) for the reaction H + D-2 -> HD- (v' = 2, j' = 0,3,6,9) + D at center-of-mass collision energies E-coll of 1.25, 1.61, and 1.97 eV using the photoloc technique. The DCSs show a strong dependence on the product rotational quantum number. For the HD(v' = 2, j' = 0) product, the DCS is bimodal but becomes oscillatory as the collision energy is increased. For the other product states, they are dominated by a single peak, which shifts from back to sideward scattering as j' increases, and they are in general less sensitive to changes in the collision energy. The experimental results are compared to quantum mechanical calculations and show good, but not fully quantitative agreement.
Y1  - 2011
U6  - https://doi.org/10.1039/c0cp02460k
SN  - 1463-9076
VL  - 13
IS  - 18
SP  - 8175
EP  - 8179
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Jankunas, Justin
A1  - Zare, Richard N.
A1  - Bouakline, Foudhil
A1  - Althorpe, Stuart C.
A1  - Herraez-Aguilar, Diego
A1  - Aoiz, F. Javier
T1  - Seemingly anomalous angular distributions in H+D-2 reactive scattering
JF  - Science
N2  - When a hydrogen (H) atom approaches a deuterium (D-2) molecule, the minimum-energy path is for the three nuclei to line up. Consequently, nearly collinear collisions cause HD reaction products to be backscattered with low rotational excitation, whereas more glancing collisions yield sideways-scattered HD products with higher rotational excitation. Here we report that measured cross sections for the H + D-2 -> HD(v' = 4, j') + D reaction at a collision energy of 1.97 electron volts contradict this behavior. The anomalous angular distributions match closely fully quantum mechanical calculations, and for the most part quasiclassical trajectory calculations. As the energy available in product recoil is reduced, a rotational barrier to reaction cuts off contributions from glancing collisions, causing high-j' HD products to become backward scattered.
Y1  - 2012
U6  - https://doi.org/10.1126/science.1221329
SN  - 0036-8075
VL  - 336
IS  - 6089
SP  - 1687
EP  - 1690
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bouakline, Foudhil
A1  - Althorpe, Stuart C.
A1  - Larregaray, Pascal
A1  - Bonnet, Laurent
T1  - Strong geometric-phase effects in the hydrogen-exchange reaction at high collision energies : II. quasiclassical trajectory analysis
N2  - Recent calculations on the hydrogen-exchange reaction [Bouakline et al., J. Chem. Phys. 128, 124322 (2008)], have found strong geometric phase (GP) effects in the state-to-state differential cross-sections (DCS), at energies above the energetic minimum of the conical intersection (CI) seam, which cancel out in the integral cross-sections (ICS). In this article, we explain the origin of this cancellation and make other predictions about the nature of the reaction mechanisms at these high energies by carrying out quasiclassical trajectory (QCT) calculations. Detailed comparisons are made with the quantum results by splitting the quantum and the QCT cross-sections into contributions from reaction paths that wind in different senses around the CI and that scatter the products in the nearside and farside directions. Reaction paths that traverse one transition state (1-TS) scatter their products in just the nearside direction, whereas paths that traverse two transition states (2-TS) scatter in both the nearside and farside directions. However, the nearside 2-TS products scatter into a different region of angular phase-space than the 1-TS products, which explains why the GP effects cancel out in the ICS. Analysis of the QCT results also suggests that two separate reaction mechanisms may be responsible for the 2-TS scattering at high energies.
Y1  - 2010
UR  - http://www.informaworld.com/openurl?genre=journal&issn=0026-8976
U6  - https://doi.org/10.1080/00268971003610218
SN  - 0026-8976
ER  -