76
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Lepage M, Michaud M, Sanche L. Low-energy electron scattering cross section for the production of CO within condensed acetone. J Chem Phys 2000. [DOI: 10.1063/1.1287400] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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77
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Abdoul-Carime H, Huels MA, Brüning F, Illenberger E, Sanche L. Dissociative electron attachment to gas-phase 5-bromouracil. J Chem Phys 2000. [DOI: 10.1063/1.1306654] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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78
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Weik F, Sanche L, Ingólfsson O, Illenberger E. Stabilization of transient negative ions by vibrational energy transfer: A cluster and thin film study on SF6 and C6F6. J Chem Phys 2000. [DOI: 10.1063/1.481516] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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79
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Antic D, Parenteau L, Sanche L. Electron-Stimulated Desorption of H- from Condensed-Phase Deoxyribose Analogues: Dissociative Electron Attachment versus Resonance Decay into Dipolar Dissociation. J Phys Chem B 2000. [DOI: 10.1021/jp000206m] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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80
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Lepage M, Michaud M, Sanche L. Low-energy electron-energy-loss spectroscopy of condensed acetone: Electronic transitions and resonance-enhanced vibrational excitations. J Chem Phys 2000. [DOI: 10.1063/1.481245] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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81
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Boudaïffa B, Cloutier P, Hunting D, Huels MA, Sanche L. Resonant formation of DNA strand breaks by low-energy (3 to 20 eV) electrons. Science 2000; 287:1658-60. [PMID: 10698742 DOI: 10.1126/science.287.5458.1658] [Citation(s) in RCA: 1228] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Most of the energy deposited in cells by ionizing radiation is channeled into the production of abundant free secondary electrons with ballistic energies between 1 and 20 electron volts. Here it is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components. This finding presents a fundamental challenge to the traditional notion that genotoxic damage by secondary electrons can only occur at energies above the onset of ionization, or upon solvation when they become a slowly reacting chemical species.
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82
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Tronc M, Azria R, Coat Y, Cloutier P, Sanche L. Kinetic energy distributions for O− and metastable CO* produced by electron stimulated desorption from condensed CO2. Chem Phys 2000. [DOI: 10.1016/s0301-0104(00)00015-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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83
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Abdoul-Carime H, Dugal PC, Sanche L. Damage induced by 1-30 eV electrons on thymine- and bromouracil-substituted oligonucleotides. Radiat Res 2000; 153:23-8. [PMID: 10630974 DOI: 10.1667/0033-7587(2000)153[0023:dibeeo]2.0.co;2] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The impact of low-energy (1-30 eV) electrons on self-assembled monolayers of heterogeneous oligonucleotides chemisorbed on a gold surface has been investigated by mass spectrometry of desorbed neutral species in an attempt to understand the consequences of secondary electron damage in a short sequence of a DNA single strand. We demonstrate that the most intense observable neutral species (CN, OCN and/or H(2)NCN) desorbed from Cy(6)-Th(3) and Cy(6)-(BrdU)(3) oligos are related to primary fragmentation of the bases induced by electron impact. The dependence of the neutral species desorption on electron energy shows typical signatures of dissociative electron attachment initiated by the formation of shape- and core-excited resonances (i.e. single-electron and two-electron- one-hole transitory anions, respectively). Substitution of dTh by BrdU increases the production of neutral fragments by as much as a factor of about 3 for the entire electron energy range. When the distribution of secondary electrons along radiation tracks in H(2)O is taken into account, we show that the probability for electron damage to heterogeneous oligonucleotides is enhanced by a factor of 2.5-3 for electron energies below 20 eV for both sensitized and unsensitized strands.
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84
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Antic D, Parenteau L, Lepage M, Sanche L. Low-Energy Electron Damage to Condensed-Phase Deoxyribose Analogues Investigated by Electron Stimulated Desorption of H- and Electron Energy Loss Spectroscopy. J Phys Chem B 1999. [DOI: 10.1021/jp990686l] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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85
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Vichnevetski E, Cloutier P, Sanche L. Sample morphology and porosity in electron stimulated desorption: N2* from N2 adsorbed onto glassy and crystalline n-hexane. J Chem Phys 1999. [DOI: 10.1063/1.478714] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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86
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Dugal PC, Huels MA, Sanche L. Low-energy (5-25 eV) electron damage to homo-oligonucleotides. Radiat Res 1999; 151:325-33. [PMID: 10073671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Radiation-induced damage to homo-oligonucleotides is investigated by electron-stimulated desorption of neutral fragments from chemisorbed organic films. Six and 12 mers of cytidine phosphate (poly dCs) and thymidine phosphate (poly dTs) are chemisorbed from various solutions onto a crystalline gold substrate by a thiol modification at the 3' end and are irradiated under ultra-high vacuum conditions with 5-25 eV electrons. The mass selected neutral desorption yields consist mainly of fragments of the DNA bases, i.e. CN and OCN (and/or H2NCN for poly dCs) from both poly dCs and poly dTs, indicating that the electrons interact specifically via fragmentation of the aromatic ring of either of the bases. Other heavier fragments are also detected such as H3CC-CO from poly dTs. The yields generally possess a threshold near 5 eV and a broad maximum around 12-13 eV incident electron energy. Dissociative electron attachment as well as electronically excited neutral or cation states are believed to be responsible for the various desorption yields. The latter yields are consistently larger for oligos chemisorbed from water and acetone solutions, compared to methanol solution. The invariance of the fragment yield intensities with oligo length suggests that the molecules are likely to adsorb almost parallel to the surface.
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87
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Klyachko DV, Huels MA, Sanche L. Halogen anion formation in 5-halouracil films: X rays compared to subionization electrons. Radiat Res 1999; 151:177-87. [PMID: 9952302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The radiosensitization properties of 5-halouracils (5-FU, 5-BrU and 5-IU), i.e. the enhanced sensitivity of biological media containing these compounds to ionizing radiation, have been studied using surface science methods. We show that soft X rays and near 0 eV electrons both induce dissociation of 5-halouracils into a halogen anion and a uracilyl radical. The yield of anions from 5-FU is much smaller than that from the bromo- and iodo-analogs. We explain the high anion yields in 5-BrU and 5-IU with dissociative electron attachment (DEA) of near 0 eV electrons. The thermodynamic threshold for DEA to 5-FU is near 2 eV and therefore prohibits dissociation by near 0 eV electrons.
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88
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Bass AD, Sanche L. Absolute and effective cross-sections for low-energy electron-scattering processes within condensed matter. RADIATION AND ENVIRONMENTAL BIOPHYSICS 1998; 37:243-257. [PMID: 10052674 DOI: 10.1007/s004110050125] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Within the last two decades, a number of experimental techniques have been developed to measure mean free paths and absolute and effective cross-sections for various processes related to the interaction of low-energy electrons with condensed matter. In all of the experiments, a monochromatic electron beam impinges on a thin multilayer film composed of atoms and/or molecules condensed on a metal or semiconductor substrate held at cryogenic temperatures in an ultra-high-vacuum system. Depending on the apparatus, cross-sections are obtained from low-energy electron transmission (LEET), high-resolution electron energy loss (HREEL), x-ray photoelectron (XPS) spectroscopy, electron-stimulated desorption (ESD) of neutral and ions, or a combination of these techniques. Quasi-elastic and inelastic mean free paths have been extracted from LEET data. This method has also served to generate absolute cross-sections for electron trapping and fragment production from the dissociation of transient molecular anions. In amorphous ice, a complete set of absolute cross-sections for all inelastic losses by 1-20 eV electrons has been obtained from HREEL data. Effective cross-sections for neutral and ionic radical formation were generated by desorption and XPS experiments. These various methods are briefly described in this article, and the corresponding cross-sections in the range 0-20 eV summarized.
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89
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Bass AD, Parenteau L, Huels MA, Sanche L. Reactive scattering of O− in organic films at subionization collision energies. J Chem Phys 1998. [DOI: 10.1063/1.477530] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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90
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Lepage M, Letarte S, Michaud M, Motte-Tollet F, Hubin-Franskin MJ, Roy D, Sanche L. Electron spectroscopy of resonance-enhanced vibrational excitations of gaseous and solid tetrahydrofuran. J Chem Phys 1998. [DOI: 10.1063/1.477223] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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91
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Simpson WC, Orlando TM, Parenteau L, Nagesha K, Sanche L. Dissociative electron attachment in nanoscale ice films: Thickness and charge trapping effects. J Chem Phys 1998. [DOI: 10.1063/1.475924] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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92
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Simpson WC, Sieger MT, Orlando TM, Parenteau L, Nagesha K, Sanche L. Dissociative electron attachment in nanoscale ice films: Temperature and morphology effects. J Chem Phys 1997. [DOI: 10.1063/1.475019] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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93
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Hedhili MN, Parenteau L, Huels MA, Azria R, Tronc M, Sanche L. The effects of different substrates on the electron stimulated desorption dynamics of O− from physisorbed O2. J Chem Phys 1997. [DOI: 10.1063/1.474996] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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94
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Jay-Gerin JP, Fraser MJ, Swiderek P, Michaud M, Ferradini C, Sanche L. Evidence for CO formation in irradiated methanol and acetone: Contribution of low-energy electron-energy-loss spectroscopy to γ-radiolysis. Radiat Phys Chem Oxf Engl 1993 1997. [DOI: 10.1016/s0969-806x(97)00017-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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95
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Lepage M, Michaud M, Sanche L. Low energy electron total scattering cross section for the production of CO within condensed methanol. J Chem Phys 1997. [DOI: 10.1063/1.474485] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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96
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Kimmel GA, Orlando TM, Cloutier P, Sanche L. Low-Energy (5−40 eV) Electron-Stimulated Desorption of Atomic Hydrogen and Metastable Emission from Amorphous Ice. J Phys Chem B 1997. [DOI: 10.1021/jp9632091] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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97
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Swiderek P, Michaud M, Sanche L. Condensed phase electron-energy-loss spectroscopy of the low-lying triplet states of acetylene. J Chem Phys 1997. [DOI: 10.1063/1.473845] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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98
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Ayotte P, Gamache J, Bass AD, Fabrikant II, Sanche L. Absolute cross sections for dissociative electron attachment to condensed CH3Cl and CH3Br: Effects of potential energy curve crossing and capture probability. J Chem Phys 1997. [DOI: 10.1063/1.473163] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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99
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Wen AT, Michaud M, Sanche L. Observation of temporary-negative-ion states in condensed methanol via vibrational excitation induced by slow electron scattering. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1996; 54:4162-4170. [PMID: 9913966 DOI: 10.1103/physreva.54.4162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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100
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Swiderek P, Michaud M, Sanche L. Vibronic structure in the low‐lying singlet–triplet transitions of benzene and toluene. J Chem Phys 1996. [DOI: 10.1063/1.471852] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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