Mass spectra of negative ions of anabasine and esters of lupinine

Conclusions The mass spectra of negative ions of anabasine derivatives and lupinine esters have been studied. The resonance capture of slow electrons to form both fragmentary and molecular ions strongly depends on the donor-acceptor properties of the substituents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2249–2253, October, 1981.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

The multi-functional aspect of scanning holographic microscopy: a review(Invited Paper)

Recent developments in scanning holographic microscopy that offer the prospects of new quantitative tools and imaging modalities in bio, micro, and nano sciences are reviewed. The versatility of the method is emphasized. Scanning holography can operate in an incoherent mode for fluorescence imaging, in a coherent mode for quantitative phase imaging, or in a tomographic mode for axial sectioning and rejection of the out-of-focus haze. Possible applications are illustrated with examples, and future prospects ...     

Mass spectrometry of o−, m−, and p-carboranes(12)

Conclusions Under electron impact conditions, dehydrogenation is the main fragmentation process of isomeric carboranes(12). The progress of this process enhances with the increase of the energy of ionizing electrons and the temperature of the ionization chamber.Translated from Izvestiya Akademii Nauk-SSSR, Seriya Khimicheskaya, No. 6, pp. 1337–1340, June, 1985.     

Primitive Illumination Systems for Families of Convex Bodies in the Plane

Let F= {C₁,C₂,...,C} be a family of ndisjoint convex bodies in the plane. We say that a set Vof exterior light sources illuminates F, if for every boundary point of any member of Fthere is a point in Vsuch that is visible from ,i.e. the open line segment joining and is disjoint from F. An illumination system Vis called primitive if no proper subset of Villuminates F. Let p_max(F) denote the maximum number of points forming a primitive illumination system for F, and letp_max(n) denote the minimum of F) taken over all families Fconsisting of ndisjoint convex bodies in the plane. The aim of this paper is to investigate the quantities p_max(F) and p_max(n).     

Mechanism of negative ion formation from phenol and para-chlorophenol by interaction with free electrons

Dissociative electron attachment (DEA) to phenol and para-chlorophenol in the energy range 0-12 eV is studied. Analogies in formation of the resonance states in an ionic benzene and its derivatives are found to arise from the similarity of the aromatic base of the molecules. Differences in DEA processes are defined mainly by the influence of the functional OH-group and, to a lesser degree, by the presence of a chlorine atom. A correlation between the energies of the resonance states and ionization energies of p-chlorophenol and phenol, analogous to that found previously for phenol, is proved. On this basis it is established that the dominating mechanism for formation of molecular negative ions at energies above 5 eV is Feshbach resonance.Copyright 2000 John Wiley & Sons, Ltd.     

Processes of dissociative electron capture by 20-hydroxyecdysone molecules

The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by the elimination of H₂O and H₂ molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH₂O]^.− (n=1–3) and [M−H₂−nH₂O]^.− (n=0−3) ions that are generated exclusively by the rearrangement. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000.     

Rearrangement and predissociation processes in negative molecular ions of nitrobenzenes

The reactions of resonant electron capture by the molecules of benzene nitroderivatives has been studied in the gas phase. Some fragment negative ions were found to be unstable with respect to electron autodetachment. This circumstance has been used for the determination of their structure. In particular, it has been established that the low measured appearance energy of neutral component of [M? H]^? ion beam is a result of isomerization of nitrobenzenes' molecular ion, leading to the 2‐nitrosophenol structure with the subsequent formation of the phenoxide anion in the autodetaching state. The effective yield curves of some types of fragment ions demonstrate fine vibrational structures, testifying the predissociation mechanism of ion formation. For all detected ions, the absolute cross sections of formation have been measured. Copyright © 2009 John Wiley & Sons, Ltd.