Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O 4 - anion

Dmitry Khuseynov; Daniel J. Goebbert; Andrei Sanov

doi:10.1063/1.3691104

Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O ₄ ^- anion

Dmitry Khuseynov, Daniel J. Goebbert, Andrei Sanov

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Abstract

The electronic structure and photochemistry of the O _2n ^-(H ₂O) _m, n 1-6, m 0-1 cluster anions is investigated at 532 nm using photoelectron imaging and photofragment mass-spectroscopy. The results indicate that both pure oxygen clusters and their hydrated counterparts with n 2 form an O ₄ ^- core. Fragmentation of these clusters yields predominantly O ₂ ^- and O ₂ ^-H ₂O anionic products, with the addition of O ₄ ^- fragments for larger parent clusters. The fragment autodetachment patterns observed for O ₆ ^- and larger O _2n ^- species, as well as some of their hydrated counterparts, indicate that the corresponding O ₂ ^- fragments are formed in excited vibrational states (v 4). Yet, surprisingly, the unsolvated O ₄ ^- anion itself does not show fragment autodetachment at 532 nm. It is hypothesized that the vibrationally excited O ₂ ^- is formed in the intra-cluster photodissociation of the O ₄ ^- core anion via a charge-hopping electronic relaxation mechanism mediated by asymmetric solvation of the nascent photofragments: O ₄ ^- → O ₂ ^-(X ² _g) O ₂(a ¹ _g) → O ₂(X ³ _g ^-) O ₂ ^-(X ² _g). This process depends on the presence of solvent molecules and leads to vibrationally excited O ₂ ^-(X ² _g) products.

Original language	English (US)
Article number	094312
Journal	Journal of Chemical Physics
Volume	136
Issue number	9
DOIs	https://doi.org/10.1063/1.3691104
State	Published - Mar 7 2012

ASJC Scopus subject areas

Physics and Astronomy(all)
Physical and Theoretical Chemistry

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@article{a19b776a278f4ad89071d8bfb795619a,

title = "Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O 4 - anion",

abstract = "The electronic structure and photochemistry of the O 2n -(H 2O) m, n 1-6, m 0-1 cluster anions is investigated at 532 nm using photoelectron imaging and photofragment mass-spectroscopy. The results indicate that both pure oxygen clusters and their hydrated counterparts with n 2 form an O 4 - core. Fragmentation of these clusters yields predominantly O 2 - and O 2 -H 2O anionic products, with the addition of O 4 - fragments for larger parent clusters. The fragment autodetachment patterns observed for O 6 - and larger O 2n - species, as well as some of their hydrated counterparts, indicate that the corresponding O 2 - fragments are formed in excited vibrational states (v 4). Yet, surprisingly, the unsolvated O 4 - anion itself does not show fragment autodetachment at 532 nm. It is hypothesized that the vibrationally excited O 2 - is formed in the intra-cluster photodissociation of the O 4 - core anion via a charge-hopping electronic relaxation mechanism mediated by asymmetric solvation of the nascent photofragments: O 4 - → O 2 -(X 2 g) O 2(a 1 g) → O 2(X 3 g -) O 2 -(X 2 g). This process depends on the presence of solvent molecules and leads to vibrationally excited O 2 -(X 2 g) products.",

author = "Dmitry Khuseynov and Goebbert, {Daniel J.} and Andrei Sanov",

note = "Funding Information: This work is supported by the U.S. National Science Foundation (Grant No. CHE-1011895). D.K. would also like to thank the State of Arizona TRIF Imaging Fellowship program for partial support.",

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doi = "10.1063/1.3691104",

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T2 - Solvent-mediated dissociation of the core O 4 - anion

AU - Khuseynov, Dmitry

AU - Goebbert, Daniel J.

AU - Sanov, Andrei

N1 - Funding Information: This work is supported by the U.S. National Science Foundation (Grant No. CHE-1011895). D.K. would also like to thank the State of Arizona TRIF Imaging Fellowship program for partial support.

PY - 2012/3/7

Y1 - 2012/3/7

N2 - The electronic structure and photochemistry of the O 2n -(H 2O) m, n 1-6, m 0-1 cluster anions is investigated at 532 nm using photoelectron imaging and photofragment mass-spectroscopy. The results indicate that both pure oxygen clusters and their hydrated counterparts with n 2 form an O 4 - core. Fragmentation of these clusters yields predominantly O 2 - and O 2 -H 2O anionic products, with the addition of O 4 - fragments for larger parent clusters. The fragment autodetachment patterns observed for O 6 - and larger O 2n - species, as well as some of their hydrated counterparts, indicate that the corresponding O 2 - fragments are formed in excited vibrational states (v 4). Yet, surprisingly, the unsolvated O 4 - anion itself does not show fragment autodetachment at 532 nm. It is hypothesized that the vibrationally excited O 2 - is formed in the intra-cluster photodissociation of the O 4 - core anion via a charge-hopping electronic relaxation mechanism mediated by asymmetric solvation of the nascent photofragments: O 4 - → O 2 -(X 2 g) O 2(a 1 g) → O 2(X 3 g -) O 2 -(X 2 g). This process depends on the presence of solvent molecules and leads to vibrationally excited O 2 -(X 2 g) products.

AB - The electronic structure and photochemistry of the O 2n -(H 2O) m, n 1-6, m 0-1 cluster anions is investigated at 532 nm using photoelectron imaging and photofragment mass-spectroscopy. The results indicate that both pure oxygen clusters and their hydrated counterparts with n 2 form an O 4 - core. Fragmentation of these clusters yields predominantly O 2 - and O 2 -H 2O anionic products, with the addition of O 4 - fragments for larger parent clusters. The fragment autodetachment patterns observed for O 6 - and larger O 2n - species, as well as some of their hydrated counterparts, indicate that the corresponding O 2 - fragments are formed in excited vibrational states (v 4). Yet, surprisingly, the unsolvated O 4 - anion itself does not show fragment autodetachment at 532 nm. It is hypothesized that the vibrationally excited O 2 - is formed in the intra-cluster photodissociation of the O 4 - core anion via a charge-hopping electronic relaxation mechanism mediated by asymmetric solvation of the nascent photofragments: O 4 - → O 2 -(X 2 g) O 2(a 1 g) → O 2(X 3 g -) O 2 -(X 2 g). This process depends on the presence of solvent molecules and leads to vibrationally excited O 2 -(X 2 g) products.

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Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O ₄ ^- anion

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