Interference structures in the differential cross-sections for inelastic scattering of NO by Ar

Abstract

Inelastic scattering is a fundamental collisional process that plays an important role in many areas of chemistry, and its detailed study can provide valuable insight into more complex chemical systems. Here, we report the measurement of differential cross-sections for the rotationally inelastic scattering of NO(X2Π1/2, v=0, j=0.5, f) by Ar at a collision energy of 530 cm(-1) in unprecedented detail, with full Λ-doublet (hence total NO parity) resolution in both the initial and final rotational quantum states. The observed differential cross-sections depend sensitively on the change in total NO parity on collision. Differential cross-sections for total parity-conserving and changing collisions have distinct, novel quantum-mechanical interference structures, reflecting different sensitivities to specific homonuclear and heteronuclear terms in the interaction potential. The experimental data agree remarkably well with rigorous quantum-mechanical scattering calculations, and reveal the role played by total parity in acting as a potential energy landscape filter.

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND3with He

“…Because gas-phase collisions can transfer population to higherlying rotational levels, inelastic scattering experiments help 45 interpret the anomalous non-thermal microwave radiation emitted from interstellar clouds. 15,16 An important goal of scattering experiments is to determine the state-to-state differential cross section (DCS), dσ/dΩ(θ, E, i → f ), which captures the variation of the scattering cross section for a change from initial state i to 50 final state f as a function of the centre-of-mass (CM) scattering angle θ for a specified collision energy E. The DCS is expressed visually in the form of the surface distribution of particles on an expanding velocity sphere, a so-called Newton sphere.…”

Rotationally inelastic scattering of methyl radicals with Ar and N2

“…Previous studies of inelastic scattering with Ar concentrated mostly on NO, [8][9][10][31][32][33][34][35][36][37][38][39] OH, 18,21,22,24 and HCl, 40 although scattering of a polyatomic molecule with Ar has been explored in the case of NH 3 . 41,42 Molecular nitrogen was previously used as a collider in studies of the inelastic scattering of HCl.…”

“…6 This body of work extended the scope of inelastic scattering of labile free radicals, which had previously concentrated on collisions of diatomic radicals with atomic species. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] A recent article by Dagdigian reviewed collisional energy transfer calculations for small hydrocarbon intermediates 26 and highlighted computational studies of integral cross sections for collisions of methylene (CH 2 ) 27,28 and methyl radicals. 5,28,29 The methyl radical is also the first polyatomic free radical to be slowed in a Zeeman decelerator using a pulsed magnetic field, 30 opening up new possibilities to study inelastic and reactive scattering at very low collision energies.…”

Stark Deceleration of NO Radicals

“…Its significance to the scientific community was further cemented by its proclamation as "Molecule of the Year" in 1992. In molecular beam laboratories, the NO radical in the X 2 Π 1/2 ground state has been one of the most favorite species to use in, for instance, scattering experiments [22][23][24]. NO is one of the few open-shell radicals that can be stored at large pressure in the gasphase, and can be directly seeded at large quantities in a carrier gas.…”