Controlled Neutralization Of Anions In Cryogenic Matrices By Near-threshold Photodetachment

Ludwig, Ryan M

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https://hdl.handle.net/2142/51183 Copy

Description

Title

Controlled Neutralization Of Anions In Cryogenic Matrices By Near-threshold Photodetachment

Author(s)

Ludwig, Ryan M

Contributor(s)

Moore, David T.

Issue Date

2014-06-18

Keyword(s)

Mini-symposium: Beyond the Mass-to-Charge Ratio: Spectroscopic Probes of the Structures of Ions

Abstract

"Using matrix isolation FTIR, we have observed the formation of anionic copper carbonyl complexes [Cu(CO)$_{n}$]$^{-}$ (n=1-3) following co-deposition of Cu$^{-}$ and counter-cations (Ar$^{+}$ or Kr$^{+}$) into argon matrices doped with CO.\footnote{Ryan M. Ludwig and David T. Moore, J. Chem. Phys. 139, 244202 (2013).} The infrared bands have been previously assigned in argon matrix studies employing laser ablation, however they were quite weak compared to the bands for the corresponding neutral species.\footnote{Zhou, M.; Andrews, L., J. Chem. Phys. 111, 4548 (1999).} In the current study, when the deposition is carried out in fully darkened conditions at 10 K with high CO concentrations (1-2\%), only the bands for the anionic complexes are observed initially via FTIR. However, upon mild irradiation with broadband visible light, the anionic bands are rapidly depleted, with concomitant appearance of bands corresponding to neutral copper carbonyl complexes. This photo-triggered neutralization is attributed to photodetachment of electrons from the anions, which then ""flow"" through the solid argon matrix to recombine in the matrix with non-adjacent trapping sites. This mechanism is supported by the appearance of a new band near 1515 \wn, assigned to the (CO)$_{2}$$^{-}$ species in argon.\footnote{Thompson, W.E.; Jacox, M.E.; J. Chem. Phys. 91, 735 (1991).} The wavelength dependence of the photodetachment will be discussed in detail, although preliminary indications are that the thresholds for the copper carbonyls, which are normally in the infrared,\footnote{Stanzel, J. et al.; Collect. Czech. Chem. Comm. 72, 1 (2007).} are shifted into the visible region of the spectrum in argon matrices. This likely occurs because the conduction band of solid argon is known to lie about 1 eV above the vacuum level,\footnote{Harbich, W. et al.; Phys. Rev. B. 76, 104306 (2007).} and thus the electron must have at least this much energy in order to escape into the matrix and find a trapping site."

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/51183

DOI

https://doi.org/10.15278/isms.2014.WG07

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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