Ground-State Dipole-Bound Anions

Abstract

Ground-state dipole-bound anions are fragile molecular species which excess electrons are almost entirely located in a very diffuse orbital outside the molecular frame. They can be created by attachment of very low energy electrons to polar molecules or small clusters which dipole moments are larger than a practical critical value of 2.5 D. They present analogies with Rydberg atoms and their geometrical structures are nearly identical to those of their neutral parents. Experimentally, dipole-binding of electrons to polar systems is a non-perturbative and reversible ionization process, in contrast with conventional valence-binding. Examples of applications such as mass-spectrometric isomer selection of clusters or determination of electron attachment properties of isolated nucleic acid bases are given.

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

“…These are the well-known dipole-supported states, discussed originally by Fermi andTeller (1947, see also Turner, 1977) and observed in a series of experiments on charge transfer from Rydberg atoms to polar molecules and clusters (Desfranc¸ois et al, 1994a, b, c;Desfranc¸ois et al, 1996;Compton and Hammer, 2001 (Bardsley and Mandl, 1968;Domcke and Cederbaum, 1981;Gauyacq and Herzenberg, 1982).…”

“…Energy redistribution into soft intermolecular modes may lead to long-lived homogeneous ions with size p ¼ N. Desfranc¸ois et al (1996) for dipole bound anions. The strong rise in the free electron attachment yield towards zero energy is attributed to the influence of these weakly bound (N 2 O) N À capture states without intramolecular excitation (but possibly with some intermolecular excitation).…”

Long-Range Electron Binding to Quadrupolar Molecules

“…In that case, we have to consider the presence of a quadrupolar potential plus a polarization potential as responsible for the long-range electron binding 10,11 .…”

“…RET studies were made at Université Paris-Nord (UPN) 10 and at the University of Tennessee (UT) 13 . A neutral molecular beam is created by seeding helium with succinonitrile followed by expansion through a pulsed valve.…”

Computational and photoelectron spectroscopic study of the dipole-bound anions, indole(H2O)1,2−

“…[7][8][9][10][11] The photoelectron spectrum of a dipole-bound anion usually exhibits a sharp peak at a rather low electron binding energy, with a few low intensity features due to molecular vibrations in the system. Many dipole-bound anions have been studied, including those by us, e.g., (H 2 O) 2 − , (HF) 2 − , 12 uracil − , thymine − , 13 and glycine(H 2 O) 6 − .…”