Collisions of electronically excited molecules: differential cross-sections for rotationally inelastic scattering of NO(A²Σ⁺) with Ar and He

Abstract

The paper reports experimental measurements and theoretical calculations of rotational-state-resolved differential scattering cross-sections (DCS) for collisions between electronically excited NO(A 2 AE þ ) molecules and rare gas atoms. The experimental NO(A 2 AE þ ) þ Ar and NO(A 2 AE þ ) þ He state-resolved product scattering distributions are determined using velocity-mapped ion imaging. The ion images are analysed to determine the state-resolved DCS, which are compared with new theoretical DCS calculated using quantum scattering methods on ab initio electronic potential energy surfaces. Both collision systems are imaged simultaneously; this constraint on the collision energies of the two systems aids the comparison to theory. The experimental and calculated DCS agree well for the NO(A 2 AE þ )/He system. For the NO(A 2 AE þ )/Ar scattering system, the experiments do not recover the degree of forward-scattering theoretically predicted and significant differences in the positions of the observed and predicted rotational rainbow features are apparent at large scattering angles, particularly for the most rotationally inelastic collision channels investigated: DN ¼ 12,14.

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 .…”

Reactive scattering dynamics of rotational wavepackets: A case study using the model H+H2 and F+H2 reactions with aligned and anti-aligned H2

“…This method has been successfully employed in the observation of the differential cross section of electronically excited NO(A) with Ar and He. 43 In our case, the detection laser(s) will ionise molecules in a particular product rovibrational state regardless of whether or not the molecule was initially in a rotational wavepacket state, giving rise to some degree of background signal. The level of this background signal will depend solely on the excitation efficiency within the excitation laser volume, which is sufficiently high that the experiment should be feasible.…”

Editorial

“…Molecular Physics has a long tradition in publishing articles on quantum reaction dynamics, both experimental and theoretical. Recent examples include, for example, a joint experimental and theoretical study of fully -doublet quantum state-resolved differential cross sections for collisions of NO(X) with neon [1], an experimental and theoretical study of rotationally inelastic scattering of NO(A 2 + ) with Ar and He [2], or a crossed molecular beam and QCT study of the Cl + CH 4 (v b = 0, 1) reaction [3]. An earlier Topical Review of Manthe [4] summarised recent developments in the exact QM calculation of reaction rates.…”