Valence and Dipole Binding of Electrons to Uracil

Abstract

Rydberg electron attachment to gas-phase isolated uracil molecules and mixed uracil-argon clusters is examined in a crossing beam experiment. By means of reproducible uracil beam conditions, it is possible to control the electron-binding process, which is strongly influenced by solvation. Attachment followed by evaporation of a single argon atom is already sufficient to switch from dipole-bound to valence monomer uracil anions, as demonstrated by field-detachment measurements. The existence of both types of anions is in good agreement with two separate previous theoretical predictions. A DFT calculation of the valence adiabatic electron affinity of uracil provides a small but positive value of 70 meV, close to the measured value of the dipole-bound electron affinity.

A multi-agent quantum Monte Carlo model for charge transport: Application to organic field-effect transistors

“…DBS was predicted to exist for neutral molecules with sufficiently large dipole moments (>2.5D) [130][131][132][133] and had been observed, [134][135][136][137][138] usually with very low binding energies. Excited DBSs near the detachment thresholds of anions were observed by Brauman and co-workers in photodetachment cross sections.…”

Low-energy electron collisions with gas-phase uracil

“…The resulting nuclear coordinates are listed in Table I. For the elastic scattering calculations, we made an extensive exploration of the use of different basis sets and different treatments of polarization. Uracil presents unusual numerical difficulties not only because of its size and low symmetry but also because of its large dipole moment, ϳ4 − 5 debye, [36][37][38] which is sufficient to form at least one dipolebound anion state 36,[39][40][41][42][43][44] and which will strongly influence the scattering cross section at low energies. Indeed, the fixed-nuclei elastic scattering cross section for a polar molecule is formally divergent.…”

Long-Range Electron Binding to Quadrupolar Molecules

“…Calculated total energies E for the neutral and anion conformers of succinonitrile (SN) as obtained by full optimization at the DFT/B3LYP level, using home made optimized basis sets 18 …”

“…First, density functional theory (DFT/B3LYP) calculations have been performed on neutral and anion conformers, with optimized appropriate diffuse basis sets that have been proven to give accurate dipole-bound EA-values for ware dimer anions 18 . It seems that this method and basis set are also appropriate for nitrile molecules since we obtain, for the dipolebound anion of acetonitrile, EA = 11 meV, in fair agreement with the experimental value of 18 meV and very close to the most accurate ab initio value of 13 meV 19 .…”