arXiv subjects

Lucas M. Cornetta

Publications and source records attributed to Lucas M. Cornetta.

3 recordsLinked to original sources

arXiv2026

Core-valence double ionization of SF6 involving S2p, F1s and S1s inner shells

Core-valence double ionization electron spectra near the S2p, F1s and S1s edges of SF6 are presented, analyzed and compared with conventional valence photoelectron spectra and quantum chemical calculations. The core-valence spectra are energetically stretched out, revealing salient structures between 15 and 40 eV that are sufficiently separated for molecular orbital analysis. The spectra offer new insights into the electronic structure, showing that the core hole substantially rearranges the molecular orbital order. This effect can be traced to orbital localization and nodal structure, as well as to valence-to-core penetration. The singlet and triplet splittings of the dicationic states progressively decrease in all three core-valence spectra towards deeper core levels, with larger splittings for S2p than S1s, reflecting greater valence-to-core penetration and exchange interaction for S2p. By large, the MO interpretation holds in frozen or self-consistent-field representations, except for the inner parts of the F1s spectra, which require analysis in terms of MO breakdown effects. An intensity model for CV spectra is derived using an independent-channel approach, where primary core ionization is treated by dipolar coupling to a continuum and the valence electron is promoted to a second continuum through shake-off. Full spin coupling and spin selectivity between the discrete doubly ionized states and the two continuum electrons are maintained. The primary molecular photoelectron intensity is expressed as a weighted sum of atomic subshell cross sections using a one-center atomic orbital projection of the relevant molecular orbital. The calculated spectra agree well with experiment and allow detailed assignment. In particular, symmetry breaking at the F1s core-ionization site is identified and discussed.

physics.chem-ph↗

arXiv2025

Intermolecular Radiative Decay: A non-local decay mechanism providing an insider's view of the solvation shell

Aqueous solutions are crucial in chemistry, biology, environmental science, and technology. The chemistry of solutes is influenced by the surrounding solvation shell of water molecules, which have different chemical properties than bulk water due to their different electronic and geometric structure. It is an experimental challenge to selectively investigate this property-determining electronic and geometric structure. Here, we report experimental results on a novel non-local X-ray emission process, Intermolecular Radiative Decay (IRD), for the prototypical ions Na$^{+}$ and Mg$^{2+}$ in water. We show that, in IRD, an electron from the solvation shell fills a core hole in the solute, and the released energy is emitted as an X-ray photon. We analyze the underlying mechanism using theoretical calculations, and show how IRD will allow us to meet the challenge of chemically selective probing of solvation shells from within.

physics.chem-ph↗

arXiv2022

Low energy electron interactions with resveratrol and resorcinol: anion states and likely dissociation pathways

We report a computational study of the anion states of the resveratrol (RV) and resorcinol (RS) molecules, also investigating dissociative electron attachment (DEA) pathways. RV has well known beneficial effects in human health, and its antioxidant activity was previously associated with DEA reactions producing H$_2$. Our calculations indicate a valence bound state ($π^*_1$) and four resonances ($π^*_2$ to $π^*_5$) for that system. While the computed thermodynamical thresholds are compatible with DEA reactions producing H$_2$ at 0~eV, the well known mechanism involving vibrational Feshbach resonances built on a dipole bound state should not be present in RV. Our results suggest that the shallow $π^*_1$ valence bound state is expected to account for H$_2$ elimination, probably involving $π_1^*$/$σ_{\text{OH}}^*$ couplings along the vibration dynamics. The RS molecule is also an oxidant and a subunit of RV. Since two close-lying hydroxyl groups are found in the RS moiety, the H$_2$-elimination reaction in RV should take place at the RS site. Our calculations point out a correspondence between the anion states of RV and RS, and even between the thresholds. Nevertheless, the absence of bound anion states in RS, indicated by our calculations, is expected to suppress the H$_2$-formation channel at 0~eV. One is lead to conclude that the ethene and phenol subunits in RV stabilize the $π^*_1$ state, thus switching on the DEA mechanism producing H$_2$.

physics.atom-ph↗