Non-intuitive rotational reorientation in collisions of NO(A 2Σ+) with Ne from direct measurement of a four-vector correlation

Abstract

Stereodynamic descriptions of molecular collisions concern the angular correlations that exist between vector properties of the motion of the participating species, including their velocities and rotational angular momenta. Measurements of vector correlations provide a unique view of the forces acting during collisions, and are a stringent test of electronic-structure calculations of molecular interactions. Here, we present direct measurement of the four-vector correlation between initial and final relative velocities and rotational angular momenta in a molecular collision. This property, which quantifies the extent to which a molecule retains a memory of its initial sense of rotation, or handedness, as a function of scattering angle, yields insight into the dynamics of a molecular collision. We report non-intuitive changes in the handedness for specific states and scattering angles, reproduced by classical and quantum scattering calculations. Comparison to calculations on different ab initio potential energy surfaces demonstrates this measurement's exquisite sensitivity to the underlying intermolecular forces.

Steric Effects in the Inelastic Scattering of NO(X) + Ar: Side-on Orientation

“…Similarly, in a recent publication by Sharples et al, the initial (j) and nal (j ) rotational angular momenta of electronically excited NO were selected and probed, respectively, using circularly polarised light to measure the rotational reorientation upon collision with neon atoms as a function of the scattering angle. 7 Work by Perreault et al 8,17 used the Stark-induced adiabatic Raman passage (SARP) technique to align the angular momentum of HD molecules in collisions with unpolarised D 2 and H 2 molecules at cold collision energies (below 10 K). Their results show a three-fold stereodynamic preference for collisions of D 2 molecules with HD molecules that are aligned perpendicular to the relative velocity over HD molecules aligned parallel to k. 17 By means of optical methods, the molecular axis can only be aligned -either parallel or perpendicular to an axis of reference -even if circularly polarised light is used.…”

Inelastic collision dynamics of oriented NO molecules with Kr atoms

“…The stereodynamics of molecular processes provide valuable information on what conformation or relative geometry promotes a certain chemical change within a system, or, conversely, most efficiently prevents an undesired reaction from happening. These processes are determined by the electronic structure of the molecular system under study, which can be described theoretically by are used in calculations of the product distributions [2,3,[11][12][13], while optical [14][15][16][17], magnetic [18,19], and electric [4,5,7,20,21] field methods are applied to experimentally align or orient molecules and atoms prior to reaction.…”

Rainbow scattering in rotationally inelastic collisions of HCl and H$_2$

“…26,28,30 Recent experimental progress in high-resolution measurements of state-to-state DCSs and stereodynamic control of rotationally inelastic collisions may facilitate observation of rainbows with fewer averaging effects. [34][35][36][37][38][39] Indeed, rainbow structures have been observed in the state-to-state DCS of rotationally inelastic collisions for more complex systems such as He+H 2 O, 40 H 2 +NO, 41 D 2 +NO, 41,42 and CH 4 +NO 43 . Furthermore, signatures of reactive rainbows have been observed in reactions F+CH 3 D → CH 2 D + HF and F+CH 3 D → CH 3 + DF by Liu and coworkers.…”