Fully quantum state-resolved inelastic scattering of NO(X) + Kr: Differential cross sections and product rotational alignment

Fully quantum state selected and resolved inelastic scattering of NO(X) by krypton has been investigated. Initial Λ-doublet state selection is achieved using an inhomogeneous hexapole electric field. Differential cross sections and even-moment polarization dependent differential cross sections have been obtained at a collision energy of 514 cm^−1 for both spin-orbit and parity conserving and changing collisions. Experimental results are compared with those obtained from quantum scattering calculations and are shown to be in very good agreement. Hard shell quantum scattering calculations are also performed to determine the effects of the different parts of the potential on the scattering dynamics. Comparisons are also made with the NO(X)+Ar system

A new perspective: imaging the stereochemistry of molecular collisions.

The concept of the steric effect in molecular collisions is central to chemistry. In this Perspective article we review some of the progress made in studying the steric effect in inelastic and reactive collisions involving relatively small isolated atomic and molecular species. We overview the theoretical framework used to quantify the steric effect, and outline some of the key experimental approaches that can be employed to study the dynamics and mechanism of collisions involving oriented and alignment molecules. We illustrate the discussion by highlighting a few recent studies of inelastic and reactive scattering. Finally, we conclude with some reflections on possible future directions of interest

Best of Maine 2009, with recommendations for travel and adventure, food and dr

Best of Maine 2009, with recommendations for travel and adventure, food and drink, shops and services, home and garden, politics, and odds and ends. With a special focus on Lily Bay State Park in Greenville, Beth George\u27s Spelt Right bakery in Yarmouth, Lewiston private investigator Mark Cayer, the late Portland landscape architect Ellen Louise Payson, and the mother-daughter political dynasty of U.S. Rep. Chellie Pingree and Maine Speaker of the House Hannah Pingree

Rotational Orientation Effects in NO(X) + Ar Inelastic Collisions

Rotational angular momentum orientation effects in the rotationally inelastic collisions of NO(X) with Ar have been investigated both experimentally and theoretically at a collision energy of 530 cm(-1). The collision-induced orientation has been determined experimentally using a hexapole electric field to select the ϵ = -1 Λ-doublet level of the NO(X) j = 1/2 initial state. Fully quantum state resolved polarization-dependent differential cross sections were recorded experimentally using a crossed molecular beam apparatus coupled with a (1 + 1') resonance-enhanced multiphoton ionization detection scheme and subsequent velocity-map imaging. To determine the NO sense of rotation, the probe radiation was circularly polarized. Experimental orientation polarization-dependent differential cross sections are compared with those obtained from quantum mechanical scattering calculations and are found to be in good agreement. The origin of the collision-induced orientation has been investigated by means of close-coupled quantum mechanical, quantum mechanical hard shell, quasi-classical trajectory (QCT), and classical hard shell calculations at the same collision energy. Although there is evidence for the operation of limiting classical mechanisms, the rotational orientation cannot be accounted for by QCT calculations and is found to be strongly influenced by quantum mechanical effects

Angular distributions for the inelastic scattering of NO(X(2)Π) with O2(X(3)Σg(-))

The inelastic scattering of NO(X2Π) by O2(X3Σg-) was studied at a mean collision energy of 550 cm(-1) using velocity-map ion imaging. The initial quantum state of the NO(X2Π, v = 0, j = 0.5, Ω=0.5,  = -1, f) molecule was selected using a hexapole electric field, and specific Λ-doublet levels of scattered NO were probed using (1+1(')) resonantly enhanced multiphoton ionization. A modified "onion-peeling" algorithm was employed to extract angular scattering information from the series of "pancaked," nested Newton spheres arising as a consequence of the rotational excitation of the molecular oxygen collision partner. The extracted differential cross sections for NO(X) f→f and f→e Λ-doublet resolved, spin-orbit conserving transitions, partially resolved in the oxygen co-product rotational quantum state, are reported, along with O2 fragment pair-correlated rotational state population. The inelastic scattering of NO with O2 is shown to share many similarities with the scattering of NO(X) with the rare gases. However, subtle differences in the angular distributions between the two collision partners are observed

Angular distributions for the inelastic scattering of NO(X(2)Π) with O2(X(3)Σg(-))

The inelastic scattering of NO(X2Π) by O2(X3Σg-) was studied at a mean collision energy of 550 cm(-1) using velocity-map ion imaging. The initial quantum state of the NO(X2Π, v = 0, j = 0.5, Ω=0.5,  = -1, f) molecule was selected using a hexapole electric field, and specific Λ-doublet levels of scattered NO were probed using (1+1(andapos;)) resonantly enhanced multiphoton ionization. A modified andquot;onion-peelingandquot; algorithm was employed to extract angular scattering information from the series of andquot;pancaked,andquot; nested Newton spheres arising as a consequence of the rotational excitation of the molecular oxygen collision partner. The extracted differential cross sections for NO(X) f→f and f→e Λ-doublet resolved, spin-orbit conserving transitions, partially resolved in the oxygen co-product rotational quantum state, are reported, along with O2 fragment pair-correlated rotational state population. The inelastic scattering of NO with O2 is shown to share many similarities with the scattering of NO(X) with the rare gases. However, subtle differences in the angular distributions between the two collision partners are observed

Imaging quantum stereodynamics through Fraunhofer scattering of NO radicals with rare-gas atoms

Stereodynamics describes how the vector properties of molecules, such as the directions in which they move and the axes about which they rotate, affect the probabilities (or cross-sections) of specific processes or transitions that occur on collision. The main aspects of stereodynamics in inelastic atom–molecule collisions can often be understood from classical considerations, in which the particles are represented by billiard-ball-like hard objects. In a quantum picture, however, the collision is described in terms of matter waves, which can also scatter into the region of the geometrical shadow of the object and reveal detailed information on the pure quantum-mechanical contribution to the stereodynamics. Here we present measurements of irregular diffraction patterns for NO radicals colliding with rare-gas atoms that can be explained by the analytical Fraunhofer model. They reveal a hitherto overlooked dependence on (or ‘propensity rule’ for) the magnetic quantum number m of the molecules, and a previously unrecognized type of quantum stereodynamics that has no classical analogue or interpretation

Good fences make good neighbours? A comparison of conflict regulation strategies in post-war Bosnia.

This article compares the effectiveness of the consociational and the integrative approach in fostering stability in postwar Bosnia. Whereas the ethnic groups in Lijphart’s consociational model constitute the basic units on which the political structure is built, the political structure in Horowitz’s integrative model transcends ethnic divisions. The Dayton Agreement that ended the war in Bosnia contains elements of both approaches, and the balance between them has been changing in the course of its implementation. Bosnia constitutes a very suitable case for a comparison of the effect on stability of the two approaches: elements of each approach can be isolated and their effects compared, and the interplay between the approaches and the effect of international involvement can also be analysed. An international dimension and the phase of (de)escalation of the conflict are variables missing from both approaches, but it is important to include them when analysing a postwar situation. Owing to the deep divisions in the population, the numerical balance between the groups and the maximalist objectives of the dominant parties, the consociational model has been more effective in fostering stability in Bosnia. Currently, a change to an integrative structure seems premature, but a mix of the approaches has been demonstrated to be able to foster moderation