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

Abstract

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.

Differential steric effects in the inelastic scattering of NO(X) + Ar: spin–orbit changing transitions

“…The crossed molecular beam apparatus used here for the differential steric effect measurements has been described in detail elsewhere, 9,10,14,18,22,29,30 and will only be briefly discussed here. In this work, a crossed molecular beam apparatus with initial hexapole quantum state selection is coupled with final state detection via (1+1 ′ ) resonantly enhanced multi-photon ionization (REMPI) and VMI.…”

Direct observation of product-pair correlations in rotationally inelastic collisions of ND3 with D2

“…These experimental studies have been pivotal to test and develop theory, in order to calculate accurate potential energy surfaces (PESs) and to perform quantum scattering calculations using these PESs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Studies of collision energy transfer find applications in various research areas. In astrophysics, for example, the estimation of molecular abundances in the interstellar medium (ISM) from spectral line data requires collisional rate coefficients of various molecules with the most abundant interstellar species such as He, H and H 2 .…”

Correlated energy transfer in rotationally and spin–orbit inelastic collisions of NO(X2Π1/2, j = 1/2f) with O2(X3Σg−)

“…Furthermore, we study rotational excitation of NO within the X 2 P 1/2 (F 1 ) manifold, but we also study spin-orbit changing transitions to the X 2 P 3/2 (F 2 ) manifold that is located 123 cm À1 above the F 1 manifold. As is well-known from studies of RET in collisions between NO and rare gas atoms or simple molecules, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] the interaction between NO and its collision partner is governed by two nonadiabatically coupled PESs. Spin-orbit conserving F 1 -F 1 transitions probe the average of the two PESs, whereas spinorbit changing F 1 -F 2 transitions are governed by the difference of the two PESs.…”