Fundamental properties of multiply charged molecular ions, such as energetics, structure, stability, lifetime and fragmentation dynamics, are relevant to understand and model the behavior of gaseous plasmas as well as ionosphere and astrophysical environments. Experimental determinations of the Kinetic Energy Released (KER) for ions originating from dissociations reactions, induced by Coulomb explosion of doubly charged molecular ions (molecular dications) produced by double photoionization of CO₂, N₂O and C₂H₂ molecules of interest in planetary atmospheres, are reported. The KER measurement as a function of the ultraviolet (UV) photon energy in the range of 28–65 eV was extracted from the electron-ion-ion coincidence spectra obtained by using tunable synchrotron radiation coupled with ion imaging techniques at the ELETTRA Synchrotron Light Laboratory Trieste, Italy. These experiments, coupled with a computational analysis based on a Monte Carlo trajectory simulation, allow assessing the probability of escape for simple ionic species in the upper atmosphere of Mars, Venus and Titan. The measured KER in the case of H⁺, C⁺, CH⁺, CH₂⁺, N⁺, O⁺, CO⁺, N₂⁺ and NO⁺ fragment ions range between 1.0 and 5.5 eV, being large enough to allow these ionic species to participate in the atmospheric escape from such planets into space. In the case of Mars, we suggest a possible explanation for the observed behavior of the O⁺ and CO₂²⁺ ion density profiles.

On-surface molecular functionalization paved the way for the stabilization of chelated ions in different oxidation and spin states, allowing for the fine control of catalytic and magnetic properties of metalorganic networks. Considering two model systems, a reduced Co(I) and an open-shell Co(II) metal-supported 2D molecular array, we investigate the interplay between the low valence oxidation and unpaired spin state in the molecular reactivity. We show that the redox reaction taking place at the cobalt tetraphenylporphyrin/Cu(100) interface, stabilizing the low-spin Co(I) state with no unpaired electrons in its valence shell, plays a pivotal role in changing the reactivity. This goes beyond the sole presence of unpaired electrons in the valence state of the Co(II) metal–organic species, often designated as being responsible for the reactivity towards small molecules like NO and NO₂. The reversible Co–NO₂ interaction, established with the Co(I) leads to the stabilization of the Co(III) oxidation state.

The electronic structure of nitrosyl chloride (ClNO) has been investigated in the gas phase by X-ray Photoelectron (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the Cl 2p, Cl 2s, N 1s and O 1s edges in a combined experimental and theoretical study. The theoretical calculations at different levels of approximation predict ionization potential values in good agreement with the experimental data and allow us to assign the main features of the absorption spectra. An unexpected failure of the density functional model is, however, observed in the calculation of the Cl 2s binding energy, which is related to a large self-interaction error. Largely different photoabsorption cross-section patterns are experimentally observed in core excitations from the investigated quantum shells (n = 1, 2). This finding is confirmed by the oscillator strength distributions calculated at different absorption edges; in the case of the n = 2 shell the bands below the threshold are extremely weak and most of the absorption intensity is due to excitations in the continuum.

The design of 2D metal–organic frameworks (2D MOFs) takes advantage of the combination of the diverse electronic properties of simple organic ligands with different transition metal (TM) centers. The strong directional nature of the coordinative bonds is the basis for the structural stability and the periodic arrangement of the TM cores in these architectures. Here, direct and clear evidence that 2D MOFs exhibit intriguing energy‐dispersive electronic bands with a hybrid character and distinct magnetic properties in the metal cores, resulting from the interactions between the TM electronic levels and the organic ligand π‐molecular orbitals, is reported. Importantly, a method to effectively tune both the electronic structure of 2D MOFs and the magnetic properties of the metal cores by exploiting the electronic structure of distinct TMs is presented. Consequently, the ionization potential characteristic of selected TMs, particularly the relative energy position and symmetry of the 3d states, can be used to strategically engineer bands within specific metal–organic frameworks. These findings not only provide a rationale for band structure engineering in 2D MOFs but also offer promising opportunities for advanced material design.

Highly sensitive and selective gas-sensing materials are critical for applications ranging from environmental monitoring to breath analysis. A rational approach at the nanoscale is urgent to design next-generation sensing devices. In previous work, we unveiled interesting charge transfer channels at the interface between p-type doped graphene and a layer of nickel phthalocyanine (NiPc) molecules, which we believe could be successfully exploited in gas sensing devices. Here, we have investigated the graphene-NiPc interface’s response to adsorbed gas molecules via first-principles calculations. We focused on NH₃ and NO₂ as test molecules, representing electron donors and acceptors, respectively. Notably, we identified the Ni d_z² orbital as a key player in mediating the charge transfer and affecting the charge carrier density in graphene. As a proof-of-concept, we then prepared the graphene-NiPc system as a chemiresistor device and exposed it to NH₃ and NO₂ at room temperature. The sensing tests revealed excellent sensitivity and selectivity, along with a rapid recovery time and a remarkably low detection limit.