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A study of H2O2 with Threshold Photoelectron Spectroscopy (TPES) and electronic structure calculations: re-determination of the first Adiabatic Ionization Energy (AIE)

A study of H2O2 with Threshold Photoelectron Spectroscopy (TPES) and electronic structure calculations: re-determination of the first Adiabatic Ionization Energy (AIE)
A study of H2O2 with Threshold Photoelectron Spectroscopy (TPES) and electronic structure calculations: re-determination of the first Adiabatic Ionization Energy (AIE)
In this work, hydrogen peroxide has been studied with threshold photoelectron (TPE) spectroscopy and photoelectron (PE) spectroscopy. The TPE spectrum has been recorded in the 10.0–21.0 eV ionization energy region, and the PE spectrum has been recorded at 21.22 eV photon energy. Five bands have been observed which have been assigned on the basis of UCCSD(T)-F12/VQZ-F12 and IP-EOM CCSD calculations. Vibrational structure has only been resolved in the TPE spectrum of the first band, associated with the X?2Bg H2O2+ ? X?1A H2O2 ionization, on its low energy side. This structure is assigned with the help of harmonic Franck–Condon factor calculations that use the UCCSD(T)-F12a/VQZ-F12 computed adiabatic ionization energy (AIE), and UCCSD(T)-F12a/VQZ-F12 computed equilibrium geometric parameters and harmonic vibrational frequencies for the H2O2 X?1A state and the H2O2+ X?2Bg state. These calculations show that the main vibrational structure on the leading edge of the first TPE band is in the O–O stretching mode (?3) and the HOOH deformation mode (?4), and comparison of the simulated spectrum to the experimental spectrum gives the first AIE of H2O2 as (10.685 ± 0.005) eV and ?4 = (850 ± 30) and ?3 = (1340 ± 30) cm–1 in the X?2Bg state of H2O2+. Contributions from ionization of vibrationally excited levels in the torsion mode have been identified in the TPE spectrum of the first band and the need for a vibrationally resolved TPE spectrum from vibrationally cooled molecules, as well as higher level Franck–Condon factors than performed in this work, is emphasized.
1089-5639
1-10
Schio, Luca
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Alagia, Michele
bae34f48-62f2-4a2c-95df-bd384138a6b3
Dias, Antonio
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Falcinelli, Stegfano
fecd4535-ebc4-46ad-8a60-0012b0cd8ffe
Zhaunerchyk, Vitale
9e06647e-4047-456d-92f0-4d4fc702c29e
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Mok, Daniel
89c78a4b-6c37-4f0c-8026-57246a407d35
Dyke, John
46393b45-6694-46f3-af20-d7369d26199f
Stranges, Stefano
6083b375-8a6f-4456-b6bc-54d18f19244c
Schio, Luca
7f818081-20d1-4f18-bfe8-1006fc73fab7
Alagia, Michele
bae34f48-62f2-4a2c-95df-bd384138a6b3
Dias, Antonio
4dc4cc3a-7dd1-4639-b077-1f0893e3d59a
Falcinelli, Stegfano
fecd4535-ebc4-46ad-8a60-0012b0cd8ffe
Zhaunerchyk, Vitale
9e06647e-4047-456d-92f0-4d4fc702c29e
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Mok, Daniel
89c78a4b-6c37-4f0c-8026-57246a407d35
Dyke, John
46393b45-6694-46f3-af20-d7369d26199f
Stranges, Stefano
6083b375-8a6f-4456-b6bc-54d18f19244c

Schio, Luca, Alagia, Michele, Dias, Antonio, Falcinelli, Stegfano, Zhaunerchyk, Vitale, Lee, Edmond P.F., Mok, Daniel, Dyke, John and Stranges, Stefano (2016) A study of H2O2 with Threshold Photoelectron Spectroscopy (TPES) and electronic structure calculations: re-determination of the first Adiabatic Ionization Energy (AIE). Journal of Physical Chemistry A, 1-10. (doi:10.1021/acs.jpca.6b01039).

Record type: Article

Abstract

In this work, hydrogen peroxide has been studied with threshold photoelectron (TPE) spectroscopy and photoelectron (PE) spectroscopy. The TPE spectrum has been recorded in the 10.0–21.0 eV ionization energy region, and the PE spectrum has been recorded at 21.22 eV photon energy. Five bands have been observed which have been assigned on the basis of UCCSD(T)-F12/VQZ-F12 and IP-EOM CCSD calculations. Vibrational structure has only been resolved in the TPE spectrum of the first band, associated with the X?2Bg H2O2+ ? X?1A H2O2 ionization, on its low energy side. This structure is assigned with the help of harmonic Franck–Condon factor calculations that use the UCCSD(T)-F12a/VQZ-F12 computed adiabatic ionization energy (AIE), and UCCSD(T)-F12a/VQZ-F12 computed equilibrium geometric parameters and harmonic vibrational frequencies for the H2O2 X?1A state and the H2O2+ X?2Bg state. These calculations show that the main vibrational structure on the leading edge of the first TPE band is in the O–O stretching mode (?3) and the HOOH deformation mode (?4), and comparison of the simulated spectrum to the experimental spectrum gives the first AIE of H2O2 as (10.685 ± 0.005) eV and ?4 = (850 ± 30) and ?3 = (1340 ± 30) cm–1 in the X?2Bg state of H2O2+. Contributions from ionization of vibrationally excited levels in the torsion mode have been identified in the TPE spectrum of the first band and the need for a vibrationally resolved TPE spectrum from vibrationally cooled molecules, as well as higher level Franck–Condon factors than performed in this work, is emphasized.

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Accepted/In Press date: 30 March 2016
e-pub ahead of print date: 5 April 2016
Organisations: Chemistry

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Local EPrints ID: 395165
URI: http://eprints.soton.ac.uk/id/eprint/395165
ISSN: 1089-5639
PURE UUID: c9bb3cb7-6a2d-40ec-a07b-59989db69c8f
ORCID for John Dyke: ORCID iD orcid.org/0000-0002-9808-303X

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Date deposited: 25 May 2016 14:15
Last modified: 17 Dec 2019 06:48

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Contributors

Author: Luca Schio
Author: Michele Alagia
Author: Antonio Dias
Author: Stegfano Falcinelli
Author: Vitale Zhaunerchyk
Author: Edmond P.F. Lee
Author: Daniel Mok
Author: John Dyke ORCID iD
Author: Stefano Stranges

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