Electronic states of thiophenyl and furanyl radicals and dissociation energy of thiophene via photoelectron imaging of negative ions

Lori Marie Culberson, Andrei M Sanov

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We report photoelectron images and spectra of deprotonated thiophene, C4H3S-, obtained at 266, 355, and 390 nm. Photodetachment of the isomer of the anion is observed, and the photoelectron bands are assigned to the ground X2A (π) and excited A2A and B2A (π) states of the thiophenyl radical. The photoelectron angular distributions are consistent with photodetachment from the respective in-plane (Δ) and out-of-plane (π) orbitals. The adiabatic electron affinity of α-C4H3S is determined to be 2.05 ± 0.08 eV, while the B2A term energy is estimated at 1.6 ± 0.1 eV. Using the measured electron affinity and the electron affinityacidity thermodynamic cycle, the C-Hα bond dissociation energy of thiophene is calculated as DH298(H α-C4H3S) = 115 ± 3 kcalmol. Comparison of this value to other, previously reported C-H bond dissociation energies, in particular for benzene and furan, sheds light of the relative thermodynamic stabilities of the corresponding radicals. In addition, the 266 nm photoelectron image and spectrum of the furanide anion, C4H 3O-, reveal a previously unobserved vibrationally resolved band, assigned to the B2A excited state of the furanyl radical, C4H3O. The observed band origin corresponds to a 2.53 ± 0.01 eV B2A term energy, while the resolved vibrational progression (853 ± 42 cm -1) is assigned to an in-plane ring mode of α- C4H3O (B2A).

Original languageEnglish (US)
Article number204306
JournalThe Journal of Chemical Physics
Volume134
Issue number20
DOIs
StatePublished - May 28 2011

Fingerprint

Thiophenes
Electronic states
Photoelectrons
thiophenes
negative ions
photoelectrons
Negative ions
dissociation
Imaging techniques
Electron affinity
photodetachment
electron affinity
electronics
Anions
thermodynamic cycles
anions
energy
Angular distribution
furans
Benzene

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Electronic states of thiophenyl and furanyl radicals and dissociation energy of thiophene via photoelectron imaging of negative ions. / Culberson, Lori Marie; Sanov, Andrei M.

In: The Journal of Chemical Physics, Vol. 134, No. 20, 204306, 28.05.2011.

Research output: Contribution to journalArticle

@article{170c23b9b3c84b1e972d585257826043,
title = "Electronic states of thiophenyl and furanyl radicals and dissociation energy of thiophene via photoelectron imaging of negative ions",
abstract = "We report photoelectron images and spectra of deprotonated thiophene, C4H3S-, obtained at 266, 355, and 390 nm. Photodetachment of the isomer of the anion is observed, and the photoelectron bands are assigned to the ground X2A′ (π) and excited A2A″ and B2A″ (π) states of the thiophenyl radical. The photoelectron angular distributions are consistent with photodetachment from the respective in-plane (Δ) and out-of-plane (π) orbitals. The adiabatic electron affinity of α-•C4H3S is determined to be 2.05 ± 0.08 eV, while the B2A″ term energy is estimated at 1.6 ± 0.1 eV. Using the measured electron affinity and the electron affinityacidity thermodynamic cycle, the C-Hα bond dissociation energy of thiophene is calculated as DH298(H α-C4H3S) = 115 ± 3 kcalmol. Comparison of this value to other, previously reported C-H bond dissociation energies, in particular for benzene and furan, sheds light of the relative thermodynamic stabilities of the corresponding radicals. In addition, the 266 nm photoelectron image and spectrum of the furanide anion, C4H 3O-, reveal a previously unobserved vibrationally resolved band, assigned to the B2A″ excited state of the furanyl radical, •C4H3O. The observed band origin corresponds to a 2.53 ± 0.01 eV B2A″ term energy, while the resolved vibrational progression (853 ± 42 cm -1) is assigned to an in-plane ring mode of α- •C4H3O (B2A″).",
author = "Culberson, {Lori Marie} and Sanov, {Andrei M}",
year = "2011",
month = "5",
day = "28",
doi = "10.1063/1.3593275",
language = "English (US)",
volume = "134",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "20",

}

TY - JOUR

T1 - Electronic states of thiophenyl and furanyl radicals and dissociation energy of thiophene via photoelectron imaging of negative ions

AU - Culberson, Lori Marie

AU - Sanov, Andrei M

PY - 2011/5/28

Y1 - 2011/5/28

N2 - We report photoelectron images and spectra of deprotonated thiophene, C4H3S-, obtained at 266, 355, and 390 nm. Photodetachment of the isomer of the anion is observed, and the photoelectron bands are assigned to the ground X2A′ (π) and excited A2A″ and B2A″ (π) states of the thiophenyl radical. The photoelectron angular distributions are consistent with photodetachment from the respective in-plane (Δ) and out-of-plane (π) orbitals. The adiabatic electron affinity of α-•C4H3S is determined to be 2.05 ± 0.08 eV, while the B2A″ term energy is estimated at 1.6 ± 0.1 eV. Using the measured electron affinity and the electron affinityacidity thermodynamic cycle, the C-Hα bond dissociation energy of thiophene is calculated as DH298(H α-C4H3S) = 115 ± 3 kcalmol. Comparison of this value to other, previously reported C-H bond dissociation energies, in particular for benzene and furan, sheds light of the relative thermodynamic stabilities of the corresponding radicals. In addition, the 266 nm photoelectron image and spectrum of the furanide anion, C4H 3O-, reveal a previously unobserved vibrationally resolved band, assigned to the B2A″ excited state of the furanyl radical, •C4H3O. The observed band origin corresponds to a 2.53 ± 0.01 eV B2A″ term energy, while the resolved vibrational progression (853 ± 42 cm -1) is assigned to an in-plane ring mode of α- •C4H3O (B2A″).

AB - We report photoelectron images and spectra of deprotonated thiophene, C4H3S-, obtained at 266, 355, and 390 nm. Photodetachment of the isomer of the anion is observed, and the photoelectron bands are assigned to the ground X2A′ (π) and excited A2A″ and B2A″ (π) states of the thiophenyl radical. The photoelectron angular distributions are consistent with photodetachment from the respective in-plane (Δ) and out-of-plane (π) orbitals. The adiabatic electron affinity of α-•C4H3S is determined to be 2.05 ± 0.08 eV, while the B2A″ term energy is estimated at 1.6 ± 0.1 eV. Using the measured electron affinity and the electron affinityacidity thermodynamic cycle, the C-Hα bond dissociation energy of thiophene is calculated as DH298(H α-C4H3S) = 115 ± 3 kcalmol. Comparison of this value to other, previously reported C-H bond dissociation energies, in particular for benzene and furan, sheds light of the relative thermodynamic stabilities of the corresponding radicals. In addition, the 266 nm photoelectron image and spectrum of the furanide anion, C4H 3O-, reveal a previously unobserved vibrationally resolved band, assigned to the B2A″ excited state of the furanyl radical, •C4H3O. The observed band origin corresponds to a 2.53 ± 0.01 eV B2A″ term energy, while the resolved vibrational progression (853 ± 42 cm -1) is assigned to an in-plane ring mode of α- •C4H3O (B2A″).

UR - http://www.scopus.com/inward/record.url?scp=79958079964&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79958079964&partnerID=8YFLogxK

U2 - 10.1063/1.3593275

DO - 10.1063/1.3593275

M3 - Article

VL - 134

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 20

M1 - 204306

ER -