Plasma oscillations in fullerene molecules during electron capture

The anomalously wide energy range for the formation of long-lived negative molecular ions during electron capture by fullerene molecules is explained by the excitation of collective electron (plasma) oscillations in these molecules. A model for such excitations for fullerenes C₆₀ and C₇₀ is proposed on the basis of the Thomas-Fermi model. This model provides good correlation between the experimental curves of resonant electron capture and the theoretical energy dependences of the density of plasma oscillation modes.     

Method for resolution of closely situated resonance peaks for the yield of negative ions based on the energy

Conclusions A method was proposed for isolating and resolving on the basis of the energy the closely situated resonance peaks for the yield of negative ions when the mass spectrometry method is used to study the capture of electrons by molecules.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2383–2385, October, 1981.     

Thermochemical determination of the structure of negative ions with the data from resonance electron capture spectrometry. 2. 5-Substituted 2-furancarboxylic acids and their esters

The energetics of isomerization and fragmentation of carboxylic acids and their esters from the furan series were investigated in conditions of resonance electron capture with the formation of negative ions. The enthalpies of formation of fragmentary negative ions were determined and the structure of some charged and neutral products of dissociation of these compounds was established. Schemes of the hydrogen and backbone rearrangements were proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2049–2054, September, 1991.     

Specific features of the resonant electron attachment to the chlorodibenzo-p-dioxin molecules

The processes of resonant dissociative electron attachment to the molecules of dibenzo-p-dioxin and its chlorinated derivatives containing one to four chlorine atoms (totally eight compounds) were investigated. It was established that 2,3,7-trichlorodibenzo-p-dioxin; 1,2,3,4-tetrachlorodibenzo-p-dioxin; 1,3,7,8-tetrachlorodibenzo-p-dioxin, and 2,3,7,8-tetrachlorodibenzo-p-dioxin molecules are chatacterized by positive electron affinities. At electron energies below 2 eV, the electron attachment is caused by the shape resonances. Based on the energy correlation between the negative ion resonance peaks at 3—4 eV and the UV band maxima, it was suggested that electron attachment in this energy region occurs by the mechanism of inter-shell resonance with the molecular singlet-excited states as parents. The possibility for the rearrangement processes resulting in oxy-anionic structures to occur is substantiated.     

Resonance electron-capture mass spectra of azobenezene and its monosubstituted derivatives

The negative-ion mass spectra of azobenezene and its derivatives were obtained using the resonance electron-capture technique. The molecular negative ion peaks (M^?·) were found to be dominant for almost all of these compounds. Different mechanisms of formation of molecular ions in two energy regions are proposed and the pathways of fragmentation are discussed. It is shown that fragment ions are formed predominantly by direct bond breaking except for those which derive from long-lived resonance states of M^?·.     

On the structure of negative ions formed by dissociative electron attachment by monochlorophenol molecules

The energetics of negative ion formation by resonant dissociative electron attachment by o-, m-, and p-chlorophenol molecules was studied. The structures of some fragment ions and their neutral partners were established. Hidden rearrangement processes leading to the formation of oxy anions by the detachment of chlorine atoms from molecular ions were found. The O—H bond dissociation energies for o-, m-, and p-chlorophenol molecules were 3.74±0.11, 3.72±0.17, and 3.94±0.11 eV, respectively.     

DFT calculations for the structure and properties of polychlorodibenzo-<Emphasis Type="Italic">para</Emphasis>-dioxine anion-radicals

Calculations for molecules and anion-radicals (ARs) of polychlorodibenzo-para-dioxines (PCDDs) in gas phase have been performed by Becke-Lee-Yang-Parr (B3LYP) hybrid method. The peculiarity of PCDD AR structure consists in the fact that one of C-Cl bonds is approximately by 0.75 Å longer than the other C-Cl bonds and is about 2.6 Å. A symmetric structure of 2,3,7,8-tetrachlorodibenzo-para-dioxine (TCDD) AR is the local minimum on the potential energy surface, which is higher than the absolute minimum by 2.76 kcal/mol. The electron affinity values were computed. PCDDs with one or two chlorine atoms have negative values of the electron affinity, while those with three or more chlorine atoms have positive ones.     

Thermochemical determination of the structure of negative ions on the basis of data from resonance electron capture mass spectrometry. Phenol, its chlorinated derivatives and a thioanalogue

Appearance energies for [M - H](-) ions from phenol (I), 4-chlorophenol (II), pentachlorophenol (III) and pentachlorothiophenol (IV) were measured. The following thermochemical data were deduced from experiment: DeltaH(acid) values of 343.3, 335.7, 317.1 and 317.1 kcal mol(-1) for RH molecules (I, II, III, and IV, respectively) and electron affinities (EAs) of R(.) free radicals 2.55, 2.90, 3.79, and 3.65 eV, respectively. Our data for phenol (I) and 4-chlorophenol (II) demonstrate a higher stabilization of ArO(-) anions than was previously accepted. Using the enthalpic shift procedure for molecules and a series of isodesmic reactions for free radicals, earlier elaborated by the authors, a new Delta$bf H_bf fbf 0$ values for the following gas-phase species were obtained (kcal mol(-1)): C(6)Cl(5)Br (5.0), C(6)Cl(5)SH (8.5), p-ClC(6)H(4)C(.) (2. 0), C(6)Cl(5)C(.) (-15), C(6)Cl(5)S(.) (44). Copyright 2000 John Wiley & Sons, Ltd.