Low-Energy Electron Elastic Collisions with Actinide Atoms Am, Cm, Bk, Es, No and Lr: Negative-Ion Formation

The rigorous Regge-pole method is used to investigate negative-ion formation in actinide atoms through electron elastic total cross sections (TCSs) calculation. The TCSs are found to be characterized generally by negative-ion formations, shape resonances and Ramsauer-Townsend(R-T) minima, and they exhibit both atomic and fullerene molecular behavior near the threshold. Additionally, a polarization-induced metastable cross section with a deep R-T minimum is identified near the threshold in the Am, Cm and Bk TCSs, which flips over to a shape resonance appearing very close to the threshold in the TCSs for Es, No and Lr. We attribute these new manifestations to size effects and orbital collapse significantly impacting the polarization interaction. From the TCSs unambiguous and reliable ground, metastable and excited states negative-ion binding energies (BEs) for Am−, Cm−, Bk−, Es−, No− and Lr− anions formed during the collisions are extracted and compared with existing electron affinities (EAs) of the atoms. The novelty of the Regge-pole approach is in the extraction of the negative-ion BEs from the TCSs. We conclude that the existing theoretical EAs of the actinide atoms and the recently measured EA of Th correspond to excited anionic BEs.

Nitrogen monoxide as dopant for enhanced selectivity of isomeric monoterpenes in drift tube ion mobility spectrometry with 3H ionization

The ion mobility spectra of the isomeric monoterpenes α-pinene, β-pinene, myrcene, and limonene in drift tube ion mobility spectrometry (IMS) with 3H radioactive ionization are highly similar and difficult to distinguish. The aim of this work was to enhance the selectivity of IMS by the addition of nitrogen monoxide (NO) as dopant and to investigate the underlying changes in ion formation responsible for the modified ion signals observed in the ion mobility spectra. Even though 3H-based-IMS systems have been used in hyphenation with gas chromatography (GC) for profiling of volatile organic compounds (VOCs), the investigation of ion formation still remains challenging and was exemplified by the investigated monoterpenes. Nonetheless, the formation of monomeric, dimeric, and trimeric ion clusters could be tentatively confirmed by a mass-to-mobility correlation and the highly similar pattern of ion signals in the monomer region was attributed to isomerization mechanisms potentially occurring after proton transfer reactions. The addition of NO as dopant could finally lead to the formation of additional product ions and increased the selectivity of IMS for the investigated monoterpenes as confirmed by principal component analysis (PCA). The discrimination of monoterpenes in the volatile profile is highly relevant in the quality control of hops and was given as the example for application. The results indicate that additional product ions were obtained by the formation of NO+ adduct ions, next to hydride abstraction, charge transfer, or fragmentation reactions. This approach can potentially leverage selectivity issues in VOC profiling of complex matrices, such as food matrices or raw materials in combination with chemometric pattern recognition techniques. Graphical abstract

Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe

The nature of phenomena that occurs in the electrolyte during the electrochemical deposition of CoNiFe films and the mechanism leading to the difference in the relative content of elements in the electrolyte and film was clarified. This clarification was obtained with the help of a spectrophotometric study of chloride electrolytes and the electrochemical deposition of CoNiFe films at 70 °C. An experimental study of the absorption spectra and the pH values of the FeCl2, NiCl2 and CoCl2 salt solutions at concentrations of 0.005 to 1 mol/l showed the complex nature of the ion-formation balance in single-component and mixed solutions and the dependence of ion formation on acidic and alkaline additives. The deposited CoNiFe film was made from a chloride electrolyte with a component content ratio of 1:1:1 at both high (0.5 mol/l) and low (0.006 mol\l) concentrations of each component. The content of each component in the film after the electrochemical deposition of the three component solution (FeCl2, CoCl2, and NiCl2 at equal concentrations) did not correspond to the composition of the electrolyte. The mechanism for the abnormal deposition of Co, Fe, Ni occurred due to the incomplete ionization of atoms and the differences in the mobility of ions. The magnetic susceptibility of the films formed in the triple CoNiFe system was higher than that of a permalloy. Therefore, the triple system shows promise for use in magnetic field converters.

Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule

In this study we show that the biologically relevant nicotinamide molecule dissociates into a variety of fragment anions upon electron attachment. The pyridine ring remains intact in all the dissociation reactions observed via mass spectrometry.