Wigner Near-Threshold Effects in the Photoelectron Angular Distribution of NO 2
High-resolution velocity map imaged photoelectron spectra of the nitrite anion NO are measured over a range of photodetachment wavelengths between 355 and 550 nm, resolving the vibrational and rotational structure of the NO ( ) + ← NO ( ) + transition. A full rotational band model is constructed to...
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Published in | The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 123; no. 48; pp. 10418 - 10425 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
05.12.2019
|
Online Access | Get full text |
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Summary: | High-resolution velocity map imaged photoelectron spectra of the nitrite anion NO
are measured over a range of photodetachment wavelengths between 355 and 550 nm, resolving the vibrational and rotational structure of the NO
(
) +
← NO
(
) +
transition. A full rotational band model is constructed to define the spectroscopic constants of both the neutral and the lesser studied anion ground states. The corresponding photoelectron angular distributions are characterized by a large positive anisotropy parameter, with β ≈ 1.5 gradually increasing to β ≈ 1.7 upon approaching the threshold. However, at very low kinetic energies, within 0.1 eV of the threshold, β dramatically drops to 0. This behavior is a consequence of the Wigner near-threshold selectivity of the electron partial-wave cross sections, whereby an atomic p-like orbital character adjacent to the threshold is favored. The full kinetic energy dependence of β is reproduced by a new mixed spd orbital model, yielding a NO
(
) molecular-orbital decomposition of 2% p, 44% s, and 54% d character. |
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ISSN: | 1089-5639 1520-5215 |
DOI: | 10.1021/acs.jpca.9b09073 |