M. N. Panov

Ioffe Physical Technical Institute, Sankt-Peterburg, St.-Petersburg, Russia

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Publications (55)24.51 Total impact

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    ABSTRACT: The relative cross sections of processes taking place when H+ and He2+ ions with an energy of 6 z keV ( z is the ionic charge) capture an electron from molecules of C5H11NO2S methionine (proteogenic amino acid) and C6H13NO2 norleucine (nonproteogenic amino acid) are measured by time-of-flight mass spectrometry (a methionine molecule transforms into a norleucine molecule by substituting the CH2 group for the S heteroatom). The fragmentation pattern of resulting molecular ions is established from correlation analysis of the detection times of all fragment ions. The results are compared with experimental data for fragmentation of the same molecules ionized by electrons and photons. In these amino acids, the pattern of molecular ion fragmentation is found to depend on the type of molecule ionization. However, the detachment cross section of the COOH neutral group or residue (neutral or charged) R of a side chain of the amino acid is invariably among the largest. The relative cross sections of capture with single and double ionization of molecules are measured.
    Technical Physics 09/2013; 58(9):1243-1250. · 0.54 Impact Factor
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    ABSTRACT: The time-of-flight mass spectrometry method is used to study processes occurring when 36-keV multiply charged Ar ions (Ar6+) capture electrons from adenine and uracyl molecules. Adenine and uracyl constitute one of two base pairs entering into the RNA composition. The fragmentation scheme of resulting molecular ions is derived by analyzing correlations between the detection times of all fragment ions. Fragmentation patterns for molecular ions resulting from molecule ionization by photons, electrons, protons, and multiply charged ions are compared.
    Technical Physics 05/2012; 57(5). · 0.54 Impact Factor
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    ABSTRACT: Time-of-flight mass spectroscopy methods are employed for studying processes occurring during capture of electrons by 3He2+ and Ar6+ multiply charged ions with energy 6z keV (z is the ion charge) from C2H n molecules (n = 2, 4, 6) with different multiplicities of C-C bonds. Fragmentation schemes of the molecular ions formed in such processes are established from analysis of correlations of recording times for all fragment ions. The absolute values of the cross sections of capture of an electron and capture with ionization are measured, as well as the cross sections of formation of fragment ions in these processes. The absolute values of total capture cross sections for several electrons are determined.
    Technical Physics 05/2011; 56(5):597-604. · 0.54 Impact Factor
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    ABSTRACT: Formation probability of carbonic ionized clusters arising from the collisions between multiply charged ions and fullerene – C60, toluene – C7H8, benzene – C6H6 and butane – C4H10 molecules has been measured. He2+ and Ar6+ projectile ions have been used for the ionization and following fragmentation of polyatomic molecules. The charge state analysis of projectile ions after collisions made it possible to control the minimal number of electrons removed from the target molecule and, as a result, the qualitative control of its excitation energy. The recoil fragment ions formed at target molecule dissociation have been analyzed on mass and charge by time of flight system (TOF).
    Fullerenes Nanotubes and Carbon Nanostructures 07/2010; Nanotubes(and Carbon Nanostructures):441-445. · 0.64 Impact Factor
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    ABSTRACT: The subject of investigation is the fragmentation of variously charged molecular ions arising in col-lisions of several kiloelectronvolt H+, He2+, and Ar6+ ions with molecules of the simplest alkanes (from methane to butane). Using the method of time-of-flight mass spectrometry, the formation cross sections of dissociation-induced fragment ions are measured. The dissociation takes place when an incident ion captures an electron from a methane, ethane, or propane molecule. The role of additional ionization of the molecule, which accompanies the electron capture by the incident ion, is elucidated. The kinetic energy spectrum for protons resulting from the fragmentation of multiply charged alkane ions is determined. The most plausible kinetic energies of protons depending on the degree of ionization and molecule size fall into the range 1–25 eV. It is shown that, when the molecule loses several electrons, the kinetic energies of protons are governed by Coulomb interaction between all fragment ions and are determined by their flying apart from the relative spatial arrangement of corresponding atoms in a parent molecule.
    Technical Physics 03/2010; 55(3):357-366. · 0.54 Impact Factor
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    ABSTRACT: We have studied the process of fragmentation of a molecular ion of C60 fullerene, which takes place as a result of the loss of five electrons in collision with a 64-keV Ar6+ ion. The spectrum of kinetic energies of the fragment ions with a given mass, as well as the number of such ions, were determined from the shapes of lines in the mass spectrum measured using a time-of-flight analyzer. It is established that, in addition to the capture of electrons by the projectile ion, an important role in the formation of a multicharge molecular C60 ion is played by additional ionization of the target molecule. It is shown for the first time that the fragmentation of fullerene molecular ions is not a single-stage process. The kinetic energies and the mass spectrum of fragment ions are determined both by the Coulomb repulsion in a multicharge fullerene ion and by the subsequent additional decay of heavy fragment ions in the course of expansion.
    Technical Physics Letters 11/2007; 33(12):1018-1021. · 0.58 Impact Factor
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    ABSTRACT: Cross-sections for one-electron capture in collisions of C+Z (Z = 4-6), N+Z (Z = 5-7), O+Z (Z = 6-8) and Ne+Z (Z = 8-10) ions with atomic and molecular hydrogen, Ar+18 ions with H2 molecules and C+6, N+7, O+8, Ar+Z (Z = 3-8) ions with helium atoms have been measured in the range of relative velocities of the colliding particles v = (1-13) × 107 cm s-1. Populations of various electronic states of Ar+(Z-1) ions formed in the process of one-electron capture by Ar+Z (Z = 3-7) ions from He atoms have also been measured. In the investigated velocity range there is a good agreement between the obtained experimental values of cross-sections for one-electron capture and the available close-coupling calculations. Theoretical estimations of cross sections have been made on the basis of Landau-Zener model and they agree well with experimental data.
    Physica Scripta 02/2007; 1983(T3):124. · 1.03 Impact Factor
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    ABSTRACT: Mass/charge spectra of recoil ionic fragments formed in collisions of C60 molecules with keV‐energy Ar projectile ions were studied using registration of the fragments in coincidence with the projectile captured certain number of electrons s at the same single collision. Different channels of the fragmentation accompanied by additional ionization were observed. The degree of fragmentation is caused mainly by electronic excitation transferred predominantly to C60 at the electron capture and increases with s value from 1 to 6.
    Fullerenes Nanotubes and Carbon Nanostructures 08/2006; 12:485-490. · 0.64 Impact Factor
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    ABSTRACT: Fragmentation accompanying the loss of electrons by butane and isobutane (C4H10) molecules in collisions with energy H+, He2+, and Ar6+ ions of kiloelectronvolt energies is studied. The electron density functional technique is applied to C n H2n+2 alkane molecules and their respective C n H 2n+2 + ions to carry out quantum-chemical calculations of the atomic spacing, electron total energy for the initial configuration of the ionizing molecules and ions in the ground state, and atomic bond breaking energy necessary to produce different ion fragments. The fragmentation energy is correlated with the fragmentation probability. It is shown that the relative cross sections of ion fragmentation depend primarily on the related energy consumption. However, the process cross section is also strongly affected by the initial configuration of C4H10 isomer molecules, as well as by the amount of dangling and arising atomic bonds involved in the formation of each ion fragment.
    Technical Physics 01/2006; 51(12):1553-1562. · 0.54 Impact Factor
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    ABSTRACT: The population of various electronic states of particles that arise during the capture of a single electron in hydrogen and helium atoms, as well as hydrogen molecules, by Ar3+ and Ne3+ ions with an energy of several kiloelectronvolts was studied by collision spectroscopy, viz., precision analysis of kinetic energy variation for ions formed as a result of interaction between ions and atoms. It is shown that single-electron capture in many cases is a multielectron process accompanied by the rearrangement of a multiply charged ion core. It is found that the triply charged Ne3+ ions formed as a result of ionization of Ne atoms by electron impacts are formed mainly in metastable states. The population of excited states of particles during their multiple ionization should be taken into account in determining the characteristics of various particles by the appearance potential method. Collision spectroscopy can be used for analyzing the metastable ion impurities in ionic beams.
    Technical Physics 07/2005; 50(8):987-992. · 0.54 Impact Factor
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    ABSTRACT: The dissociation of C60 fullerene molecules has been studied by means of an analysis of the kinetic energies of charged fragments formed upon the capture of several electrons from C60 by multiply charged Ar6+ ions. The kinetic energies of fragment ions of a multiply ionized C60 molecule are distributed in accordance with the Coulomb explosion mechanism of dissociation.
    Technical Physics Letters 01/2005; 31(12):1055-1057. · 0.58 Impact Factor
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    ABSTRACT: Mass-to-charge spectra of ions formed in ionization of freon-12 molecules, CF2Cl2, by protons with energies of Ep = 10 keV and 1 MeV are studied for the first time. Relative probabilities of different dissociation channels of the ionized freon-12 molecule, are obtained and compared with similar data for freon-12 ionization by electrons, positrons and photons. Absolute total and partial experimental cross sections for the formation of different fragment ions are evaluated for the case Ep = 10 keV. Neutral chlorine atom detachment is found to be the main fragmentation channel at both energies studied. Calculations of geometry and binding energies of fragment ions as well as energies required for activating various dissociation channels are carried out. A qualitative explanation is given of the observed fragmentation spectra.
    Journal of Physics B Atomic Molecular and Optical Physics 05/2003; 36(10):1991. · 1.92 Impact Factor
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    ABSTRACT: This paper reports on the first measurements of the differential cross sections (with respect to scattering angle) of various elementary processes accompanying electron capture by keV-range H+ and He2+ ions from a fullerene molecule. Estimation of the impact parameter from the ion scattering angle in the polarization interaction with a fullerene molecule shows that the processes of capture and capture with fullerene ionization and fragmentation occur primarily at impact parameters far exceeding the fullerene radius.
    Physics of the Solid State 02/2002; 44(3):509-510. · 0.78 Impact Factor
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    Nuclear Fusion Special Supplement. 01/2002;
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    ABSTRACT: Time-of-flight (TOF) techniques have been used to measure singly and multiply ionized Ar recoils in coincidence with energy-analysed, forward-ejected electrons in 1 MeV H+-Ar collisions. Electron energies up to 2800 eV and charge states 1-4 are covered. It is shown experimentally that the peak of binary-encounter (BE) electrons in the electron energy spectrum is associated almost entirely with single ionization of Ar, whereas the peak of electron-capture-to-the continuum (ECC) electrons is associated with multiple ionization. This shows that the BE electrons originate exclusively from the valence shell of Ar (the M shell) and the ECC electrons predominantly from an inner shell (the L shell).
    Journal of Physics B Atomic Molecular and Optical Physics 09/2000; 33(20):4237. · 1.92 Impact Factor
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    ABSTRACT: Using coincidence technique the relative cross-sections of charge state change and fragmentation at one and two electron capture processes have been measured for the first time at collisions of He and Ar projectiles with fullerenes in the energy range (3-35)z keV.
    Fullerene Science and Technology 05/1998; 6(3):393-403.
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    ABSTRACT: The cross sections for the elementary processes involving a change of the charge states of both particles during the interaction of He2+ ions with fullerene molecules are for the first time measured over a broad energy range of electron-volt energies. It is found that processes involving the capture of one or two electrons by the He2+ ions are accompanied by additional ionization of the fullerene and that the collisional contribution of the transfer-ionization processes increases with increasing velocity. Single-electron capture is rarely accompanied by fragmentation of the fullerene. Double-electron capture leads, with a higher probability, to fragmentation with the formation of several light charged fragments and, with a smaller probability, to fragmentation with the formation of a heavy charged fragment containing an even number of carbon atoms and light fragments in an uncharged state.
    Technical Physics 03/1998; 43(4):358-360. · 0.54 Impact Factor
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    ABSTRACT: Superconducting YBa2Cu3O7−x films were prepared by magnetron sputtering on Al2O3 single crystals with a CeO2 sublayer. Scattering of moderate-energy ions and x-ray diffraction were used to show that the films exhibit good single-crystal properties over the entire thickness up to 2.6 μm. The hypothesis is advanced that the indentations formed by the growth of films above “extraneous” phase grains may act as defect sinks.
    Technical Physics Letters 01/1998; 24(1):41-42. · 0.58 Impact Factor