Vibrationally Mediated Stabilization of Electrons in Nonpolar Matter

Abstract

We explore solvation of electrons in non-polar matter, here represented by butadiene clusters. Isolated butadiene supports only the existence of transient anions (resonances). Two-dimensional electron energy loss spectroscopy shows that the resonances lead to an efficient vibrational excitation of butadiene, which can result into almost complete energy loss of the interacting electron. Cluster-beam experiments show that molecular clusters of butadiene form stable anions, however only at sizes larger than 9 molecular units. We have calculated the distribution of electron affinities of clusters using classical and path integral molecular dynamics simulations. There is almost a continuous transition from the resonant to the bound anions with the increasing cluster size. The comparison of the classical and quantum dynamics reveals that the electron binding is strongly supported by molecular vibrations, brought about by nuclear zero point motion and thermal agitation. We also inspected the structure of the solvated electron, finding it well localized.

Electron Energy Loss Processes in Methyl Methacrylate: Excitation and Bond Breaking

“…Instead of thermal electron ejection, which is observed in the gas phase, the energy is dissipated into the cluster. This phenomenon is commonly observed for clusters 63 , 64 and may be associated with evaporation of neutral monomer units. 65 We can also see a low-intensity progression of M n (H 2 O) − anions, likely formed by clustering of MMA molecules with water that is present as an impurity in the sample.…”

Interaction of low-energy electrons with radiosensitizers

“…1(a)-(e), require the formation of TNI, which means that the electron is attached to the molecule on the timescales longer than the typical period for vibrational motion. TNI can be stabilized via intramolecular vibrational energy redistribution (IVR) 13,14 or anion isomerization 15,16 to form parent molecular anion. Another means of anion stabilization represents the emission of photons, which is closely related to IVR and recently explored mainly for anions of astrophysical relevance.…”

“…52–54 In the case of overlapping energetic levels, such as in the case of molecules of the same type, this process may become more effective via resonant energy transfer. 14…”

Roadmap on dynamics of molecules and clusters in the gas phase

“…These include caging of dissociation products, energy transfer to the solvent or changing the molecular dipole moment [150][151][152][153]. Recently, another mechanism was proposed, based on a strong coupling of the inter-and intra-molecular vibrational motion [154].…”