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Near‐Infrared Spectrum of the First Excited State of Au(2) (+)

Au(2) (+) is a simple but crucial model system for understanding the diverse catalytic activity of gold. While the Au(2) (+) ground state (X(2)Σ(g) (+)) is understood reasonably well from mass spectrometry and computations, no spectroscopic information is available for its first excited state (A(2)Σ...

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Autores principales: Förstel, Marko, Pollow, Kai, Studemund, Taarna, Dopfer, Otto
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8596823/
https://www.ncbi.nlm.nih.gov/pubmed/34423877
http://dx.doi.org/10.1002/chem.202102542
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author Förstel, Marko
Pollow, Kai
Studemund, Taarna
Dopfer, Otto
author_facet Förstel, Marko
Pollow, Kai
Studemund, Taarna
Dopfer, Otto
author_sort Förstel, Marko
collection PubMed
description Au(2) (+) is a simple but crucial model system for understanding the diverse catalytic activity of gold. While the Au(2) (+) ground state (X(2)Σ(g) (+)) is understood reasonably well from mass spectrometry and computations, no spectroscopic information is available for its first excited state (A(2)Σ(u) (+)). Herein, we present the vibrationally resolved electronic spectrum of this state for cold Ar‐tagged Au(2) (+) cations. This exceptionally low‐lying and well isolated A(2)Σ((u)) (+)←X(2)Σ((g)) (+) transition occurs in the near‐infrared range. The observed band origin (5738 cm(−1), 1742.9 nm, 0.711 eV) and harmonic Au−Au and Au−Ar stretch frequencies (201 and 133 cm(−1)) agree surprisingly well with those predicted by standard time‐dependent density functional theory calculations. The linearly bonded Ar tag has little impact on either the geometric or electronic structure of Au(2) (+), because the Au(2) (+)⋅⋅⋅Ar bond (∼0.4 eV) is much weaker than the Au−Au bond (∼2 eV). As a result of 6 s←5d excitation of an electron from the antibonding σ(u) (*) orbital (HOMO‐1) into the bonding σ(g) orbital (SOMO), the Au−Au bond contracts substantially (by 0.1 Å).
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spelling pubmed-85968232021-11-22 Near‐Infrared Spectrum of the First Excited State of Au(2) (+) Förstel, Marko Pollow, Kai Studemund, Taarna Dopfer, Otto Chemistry Communications Au(2) (+) is a simple but crucial model system for understanding the diverse catalytic activity of gold. While the Au(2) (+) ground state (X(2)Σ(g) (+)) is understood reasonably well from mass spectrometry and computations, no spectroscopic information is available for its first excited state (A(2)Σ(u) (+)). Herein, we present the vibrationally resolved electronic spectrum of this state for cold Ar‐tagged Au(2) (+) cations. This exceptionally low‐lying and well isolated A(2)Σ((u)) (+)←X(2)Σ((g)) (+) transition occurs in the near‐infrared range. The observed band origin (5738 cm(−1), 1742.9 nm, 0.711 eV) and harmonic Au−Au and Au−Ar stretch frequencies (201 and 133 cm(−1)) agree surprisingly well with those predicted by standard time‐dependent density functional theory calculations. The linearly bonded Ar tag has little impact on either the geometric or electronic structure of Au(2) (+), because the Au(2) (+)⋅⋅⋅Ar bond (∼0.4 eV) is much weaker than the Au−Au bond (∼2 eV). As a result of 6 s←5d excitation of an electron from the antibonding σ(u) (*) orbital (HOMO‐1) into the bonding σ(g) orbital (SOMO), the Au−Au bond contracts substantially (by 0.1 Å). John Wiley and Sons Inc. 2021-09-15 2021-11-02 /pmc/articles/PMC8596823/ /pubmed/34423877 http://dx.doi.org/10.1002/chem.202102542 Text en © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Communications
Förstel, Marko
Pollow, Kai
Studemund, Taarna
Dopfer, Otto
Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title_full Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title_fullStr Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title_full_unstemmed Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title_short Near‐Infrared Spectrum of the First Excited State of Au(2) (+)
title_sort near‐infrared spectrum of the first excited state of au(2) (+)
topic Communications
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8596823/
https://www.ncbi.nlm.nih.gov/pubmed/34423877
http://dx.doi.org/10.1002/chem.202102542
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