Photoelectron spectroscopy of the 6-azauracil anion.
We report the photoelectron spectrum of the 6-azauracil anion. The spectrum is dominated by a broad band exhibiting a maximum at an electron binding energy (EBE) of 1.2 eV. This spectral pattern is indicative of a valence anion. Our calculations were carried out using ab initio electron propagator and other many-body methods. Comparison of the anion and corresponding neutral of 6-azauracil with those of uracil shows that substituting a nitrogen atom for C-H at the C6 position of uracil gives rise to significant changes in the electronic structure of 6-azauracil versus that of uracil. The adiabatic electron affinity (AEA) of the canonical 6-azauracil tautomer is substantially larger than that of canonical uracil. Among the five tautomeric, 6-azauracil anions studied computationally, the canonical structure was found to be the most stable. The vertical detachment energies (VDE) of the canonical, valence-bound anion of 6-azauracil and its closest "very-rare" tautomer have been calculated. Electron propagator calculations on the canonical anion yield a VDE value that is in close agreement with the experimentally determined VDE value of 1.2 eV. The AEA value of 6-azauracil, assessed at the CCSD(T) level of theory to be 0.5 eV, corresponds with the EBE value of the onset of the experimental spectrum.
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Jing
J
Chen
Angela
A
Buonaugurio
Olga
O
Dolgounitcheva
V G
VG
Zakrzewski
Kit H
KH
Bowen
J V
JV
Ortiz
D000838:Anions / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry
D000838:Anions; D014498:Uracil; C100248:azauracil