title: Rotational alignment of NO (A2Σ+) from collisions with Ne.
abstract: We report the direct angle-resolved measurement of collision-induced alignment of short-lived electronically excited molecules using crossed atomic and molecular beams. Utilizing velocity-mapped ion imaging, we measure the alignment of NO in its first electronically excited state (A(2)Σ(+)) following single collisions with Ne atoms. We prepare A(2)Σ(+) (v = 0, N = 0, j = 0.5) and by comparing images obtained using orthogonal linear probe laser polarizations, we experimentally determine the degree of alignment induced by collisional rotational excitation for the final rotational states N' = 4, 5, 7, and 9. The experimental results are compared to theoretical predictions using both a simple classical hard-shell model and quantum scattering calculations on an ab initio potential energy surface (PES). The experimental results show overall trends in the scattering-angle dependent polarization sensitivity that are accounted for by the simple classical model, but structure in the scattering-angle dependence that is not. The quantum scattering calculations qualitatively reproduce this structure, and we demonstrate that the experimental measurements have the sensitivity to critique the best available potential surfaces. This sensitivity to the PES is in contrast to that predicted for ground-state NO(X) alignment.
authors.affiliation: Sandia National Laboratories, Livermore, California 94550, United States.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Steill
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Kay
authors.forename: Grant
authors.initials: G
authors.lastname: Paterson
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Sharples
authors.forename: Jacek
authors.initials: J
authors.lastname: Kłos
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Costen
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Strecker
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: McKendrick
authors.forename: M H
authors.initials: MH
authors.lastname: Alexander
authors.forename: David W
authors.initials: DW
authors.lastname: Chandler
mesh_terms: D004583:Electrons; D008027:Light; D009356:Neon / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D055668:Photochemical Processes; D011789:Quantum Theory; D012399:Rotation; D013816:Thermodynamics
chemical_list: D009569:Nitric Oxide; D009356:Neon