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Updated: Jun 12, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photoelectron spectroscopy and thermochemistry of the peroxyacetate anion
Stephanie M Villano1, Nicole Eyet, Scott W Wren
1JILA, University of Colorado and the National Institute of Standards and Technology and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0440, USA.
Abstract:
The 351.1 nm photoelectron spectrum of the peroxyacetate anion, (CH(3)C(O)OO(-)) was measured. Analysis of the spectrum shows that the observed spectral features arise almost exclusively from transitions between the trans-conformer of the anion and the X(2)A'' and A (2)A' states of the corresponding radical. The electron affinity of trans-CH(3)C(O)OO is 2.381+/- 0.007 eV and the term energy splitting of the A (2)A' state is 0.691 +/- 0.009 eV, in excellent agreement with two prior values [Zalyubovsky et al. J. Phys. Chem. A 107, 7704 (2003); Hu et al. J. Phys. Chem. 124, 114305/1 (2006); Hu et al. J. Phys. Chem. 110, 2629 (2006)]. The gas-phase acidity of trans-peroxyacetic acid was bracketed between the acidity of acetic acid and tert-butylthiol at Delta(a)G(298)(trans-CH(3)C(O)OOH)=1439 +/- 14 kJ mol(-1) and Delta(a)H(298)(trans-CH(3)C(O)OOH)=1467+/-14 kJ mol(-1). The acidity of cis-CH(3)C(O)OOH was found by adding a calculated energy correction to the acidity of the trans-conformer; Delta(a)G(298)[cis-CH(3)C(O)OOH] = 1461 +/- 14 kJ mol(-1) and Delta(a)H(298)[cis- CH(3)C(O)OOH]=1490+/-14 kJ mol(-1). The O-H bond dissociation energies for both conformers were determined using a negative ion thermodynamic cycle to be D(0)[trans- CH(3)C(O)OOH]=381+/-14 kJ mol(-1) and D(0)[cis- CH(3)C(O)OOH]=403+/-14 kJ mol(-1). The atmospheric implications of these results and relations to the thermochemistry of peroxyacetyl nitrate are discussed briefly.
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