Total cross sections for slow-electron (1<i>–</i>20 eV) scattering in solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>O

Michaud, M.; Sanche, Léon

doi:10.1103/physreva.36.4672

Cited by 123 publications

(80 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…33,34 Given the value of ΔP Ar and taking the atomic density of an Ar monolayer (n Ar ) as that corresponding to a (111) plane in the bulk of solid Ar at 20 K (i.e., n Ar = 8.167 × 10 14 cm −2 ), 35,36 the ΔP for a gas or vapor was thus converted into a surface number density (n S ) with the relation n S = (n Ar /ΔP Ar )ΔP. 37 The uncertainty in this n S value arises essentially from the error in the individual pressure measurement ΔP at ±2.5% and in the value taken for n Ar at ±5% for a combined uncertainty of ±10%. 38 Cytosine (Aldrich Chemical Ltd., 99%) was sublimated at a temperature of 90° under UHV condition with a double-stage oven system.…”

Section: Methodsmentioning

confidence: 99%

Absolute cross sections for electronic excitations of cytosine by low energy electron impact

Bazin

Michaud

Sanche

2010

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

The absolute cross sections (CS) for electronic excitations of cytosine by electron impact between 5 and 18 eV were measured by electron-energy loss (EEL) spectroscopy of the molecule deposited at low coverage on an inert Ar substrate. The lowest EEL features found at 3.55 and 4.02 eV are ascribed to transitions from the ground state to the two lowest triplet 1 3 A′(π→π*) and 2 3 A′ (π→π*) valence states of the molecule. Their energy dependent CS exhibit essentially a common maximum at about 6 eV with a value of 1.84 × 10 −17 cm 2 for the former and 4.94 × 10 −17 cm 2 for the latter. In contrast, the CS for the next EEL feature at 4.65 eV, which is ascribed to the optically allowed transition to the 2 1 A′(π→π*) valence state, shows only a steep rise to about 1.04 × 10 −16 cm 2 followed by a monotonous decrease with the incident electron energy. The higher EEL features at 5.39, 6.18, 6.83, and 7.55 eV are assigned to the excitations of the 3 3, 1 A′(π→π*), 4 1 A′(π→π*), 5 1 A′(π→π*), and 6 1 A′(π→π*) valence states, respectively. The CS for the 3 3, 1 A′ and 4 1 A′ states exhibit a common enhancement at about 10 eV superimposed on a more or less a steep rise, reaching respectively a maximum of 1.27 and 1.79 × 10 −16 cm 2 , followed by a monotonous decrease. This latter enhancement and the maximum seen at about 6 eV in the lowest triplet states correspond to the core-excited electron resonances that have been found by dissociative electron attachment experiments with cytosine in the gas phase. The weak EEL feature found at 5.01 eV with a maximum CS of 3.8 × 10 −18 cm 2 near its excitation threshold is attributed to transitions from the ground state to the 1 3, 1 A″(n→π*) states. The monotonous rise of the EEL signal above 8 eV is attributed to the ionization of the molecule. It is partitioned into four excitation energy regions at about 8.55, 9.21, 9.83, and 11.53 eV, which correspond closely to the ionization energies of the four highest occupied molecular orbitals of cytosine. The sum of the ionization CS for these four excitation regions reaches a maximum of 8.1 × 10 −16 cm 2 at the incident energy of 13 eV.

show abstract

Section: Methodsmentioning

confidence: 99%

Absolute cross sections for electronic excitations of cytosine by low energy electron impact

Bazin

Michaud

Sanche

2010

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…One approach to determine absolute CSs of LEE interaction with condensed molecules is to perform a two-stream multiple-scattering analysis of the backscattered electron energy distribution measured by electron-energy-loss spectroscopy [29,30,37,38]. As a first step, entire EEL spectra along with the transmitted currents are measured at different molecular coverages for a fixed incident energy.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of isotropic scattering, the latter amounts to half of the integral CS. When the film thickness is comparable to or larger than the MFP of the incident electron (i.e., the multiple-collision regime), the energydependent elastic electron reflectivity (i.e., electron scattered elastically) measured as a function of the film thickness leads to the absolute value of the energy-dependent total CS (i.e., the inverse MFP) [30,37]. The latter is then used to normalize the relative elastic and inelatic integral CSs, which are obtained relative to the total CS from a detailed two-stream multiple-scattering analysis of the EEL spectra.…”

Section: Introductionmentioning

confidence: 99%

Absolute cross section for low-energy-electron damage to condensed macromolecules: A case study of DNA

et al. 2012

View full text Add to dashboard Cite

Cross sections (CSs) for the interaction of low-energy electrons (LEE) with condensed macromolecules are essential parameters for accurate modeling of radiation-induced molecular decomposition and chemical synthesis. Electron irradiation of dry nanometer-scale macromolecular solid films has often been employed to measure CSs and other quantitative parameters for LEE interactions. Since such films have thicknesses comparable with electron thermalization distances, energy deposition varies throughout the film. Moreover, charge accumulation occurring inside the films shields a proportion of the macromolecules from electron irradiation. Such effects complicate the quantitative comparison of the CSs obtained in films of different thicknesses and limit the applicability of such measurements. Here, we develop a simple mathematical model, termed the molecular survival model, that employs a CS for a particular damage process together with an attenuation length related to the total CS, to investigate how a measured CS might be expected to vary with experimental conditions. As a case study, we measure the absolute CS for the formation of DNA strand breaks (SBs) by electron irradiation at 10 and 100 eV of lyophilized plasmid DNA films with thicknesses between 10 and 30 nm. The measurements are shown to depend strongly on the thickness and charging condition of the nanometer-scale films. Such behaviors are in accord with the model and support its validity. Via this analysis, the CS obtained for SB damage is nearly independent of film thickness and charging effects. In principle, this model can be adapted to provide absolute CSs for electron-induced damage or reactions occurring in other molecular solids across a wider range of experimental conditions.

show abstract

“…So far, the only experimentally derived, absolute LEE cross sections for inclusion in MC simulations are those measured for amorphous water ice. 16,17 There exists a dearth of experimentally derived data for damage to what is arguably, the most important target in radiobiology, the DNA molecule.…”

Section: Introductionmentioning

confidence: 99%

Absolute cross section for loss of supercoiled topology induced by 10 eV electrons in highly uniform /DNA/1,3-diaminopropane films deposited on highly ordered pyrolitic graphite

Boulanouar

Fromm

Bass

et al. 2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

It was recently shown that the affinity of doubly charged, 1-3 diaminopropane (Dap 2+ ) for DNA permits the growth on highly ordered pyrolitic graphite (HOPG) substrates, of plasmid DNA films, of known uniform thickness [O. Boulanouar, A. Khatyr, G. Herlem, F. Palmino, L. Sanche, and M. Fromm, J. Phys. Chem. C 115, 21291-21298 (2011)]. Post-irradiation analysis by electrophoresis of such targets confirms that electron impact at 10 eV produces a maximum in the yield of single strand breaks that can be associated with the formation of a DNA − transient anion. Using a welladapted deterministic survival model for the variation of electron damage with fluence and film thickness, we have determined an absolute cross section for strand-break damage by 10 eV electrons and inelastic scattering attenuation length in DNA-Dap complex films.

show abstract

Total cross sections for slow-electron (1–20 eV) scattering in solidH2O

Cited by 123 publications

References 47 publications

Absolute cross sections for electronic excitations of cytosine by low energy electron impact

Absolute cross sections for electronic excitations of cytosine by low energy electron impact

Absolute cross section for low-energy-electron damage to condensed macromolecules: A case study of DNA

Absolute cross section for loss of supercoiled topology induced by 10 eV electrons in highly uniform /DNA/1,3-diaminopropane films deposited on highly ordered pyrolitic graphite

Contact Info

Product

Resources

About