Fragment ion distribution in charge-changing collisions of 2-MeV Si ions with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>60</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Itoh, Akio; Tsuchida, H.; Miyabe, K; Majima, T.; Nakai, Yutaka

doi:10.1103/physreva.64.032702

Cited by 16 publications

(7 citation statements)

References 36 publications

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“…As speculated abundantly in the literature, these distributions appear to be similar in their U shape with those obtained in fragmentation experiments implying atomic projectiles ͑C x q+ , H x + , Si q+ , Xe + , and O q− ͒. 4,[24][25][26] There are several significant findings which result from our simulations. First, the fragmentation of the fullerene occurs roughly at excitation energies larger than 95 eV ͑ap-proximately 6000 K͒, in very good agreement with values obtained in previous simulations of fullerene fragmentation and melting, performed by Kim et al 10,11 For lower energies, the cage remains stable over a very long period of time, only a slight deformation being noticeable.…”

Section: Resultssupporting

confidence: 78%

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Tight-binding molecular dynamics simulations of radiation-induced fragmentation ofC60

Horváth

Beu

2008

Phys. Rev. B

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The fragmentation of the C 60 fullerene was investigated using tight-binding molecular dynamics simulations based on the parametrization of Papaconstantopoulos et al. ͓MRS Symposia Proceedings No. 491 ͑Materials Research Society, Pittsburgh, 1998͒, p. 221͔. Averaged fragment size distributions over random sets of initial configurations were obtained from simulations of radiation-induced fragmentation in the 50-500 eV excitation energy range. The excitation caused by the radiation was simulated simply by ascribing suddenly random velocities to each atom of the fullerene cage. For low excitation energies, the size distributions are peaked for dimers ͑reflecting a preferential C 2 emission͒ and a bimodal size dependence characterizes the distributions of the complementary small and large fragments. For high excitation energies, predominantly multifragmentation occurs, but a genuine power-law dependence of small fragments is not yet observable. A phase transition is found for rather low excitation energies ͑100-120 eV͒.

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Section: Resultssupporting

confidence: 78%

“…Itoh et al 24,27 emphasized that, provided the excitation energy is large enough, the small fragment distributions follow an n − power law. 4 LeBrun et al 25 have measured an inclusive TOF spectrum ͑summed over the impact parameter͒ of charged fragments produced in collisions of 625 MeV Xe 35+ ions with C 60 targets.…”

Section: Resultsmentioning

confidence: 98%

Tight-binding molecular dynamics simulations of radiation-induced fragmentation ofC60

Horváth

Beu

2008

Phys. Rev. B

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“…1,3,18,19 Nevertheless, irrespective of the excitation energy, in highly ionized states the U-shaped size distributions disappear, since the strong electrostatic repulsion between and within clusters produces further disintegration into smaller fragments. A simple square root dependence on the fullerene size of the limiting ionization charge still producing U-shaped distributions has been found to hold for all studied fullerene species.…”

Section: Discussionmentioning

confidence: 95%

“…Overall, the size distribution patterns appear to be similar to those from a wide variety of fragmentation experiments with atomic projectiles. 3,[16][17][18][19] The average fragmentation probability, providing the most synthetic description of the overall features of the fragmentation process, is defined for each trajectory ensemble as the ratio of the number of dissociative trajectories to the total number of trajectories. The excitation energies corresponding to the lowest panels of Figs.…”

Section: Resultsmentioning

confidence: 99%

Radiation-induced fragmentation of fullerenes

Beu

Jurjiu

2011

Phys. Rev. B

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The radiation-induced fragmentation of the fullerenes C 36 , C 60 , C 70 , and C 96 was investigated by tight-binding molecular dynamics simulations. The resulting fragment size and fragment charge distributions, averaged over large ensembles of trajectories corresponding to total ionization states up to +20e and excitation energies up to 300 eV, have been used to analyze the fragmentation statistics in terms of several derived quantities. A well-defined phase transition region is found in the total charge-excitation energy plane, which appears to be delimited by critical lines depending quadratically on the total ionization charge and linearly on the fullerene size.

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“…In a study on MeV Si q + collisions with C 60 , Itoh et al have already concluded that t carries information about the energy deposition E exc into the target molecule. [10] In their work, the target excitation energies E exc were calculated and a simple exponential dependence of E exc on the characteristic exponent t was found. However, the value of E exc was not experimentally obtained in their study.…”

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confidence: 99%

Precise Determination of 2‐Deoxy‐D‐Ribose Internal Energies after keV Proton Collisions

Alvarado

Bernard

et al. 2008

ChemPhysChem

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The interaction of keV protons with building blocks of DNA is of particular biological relevance in view of the increasing number of facilities employing MeV proton irradiation for tumor treatment.[1] When ions traverse tissue and are decelerated to MeV and sub-MeV energies, the Bragg peak is reached. At ion energies in the Bragg peak region, the induced damage is highest due to maximum linear energy transfer and relative biological effectiveness. The volume selectivity given by the existence of a well-localized Bragg peak region renders proton therapy such a promising tool for cancer treatment. [2] Furthermore, biological consequences of irradiation with energetic protons from galactic cosmic rays and solar particle events are a limiting factor for human space exploration. This issue is of particular importance for future manned missions outside low earth orbit, for example, lunar or Mars missions. [3] It is well-known that biological radiation damage is the ultimate result of ionization and fragmentation of cellular DNA. To explore the molecular mechanisms underlying radiation-induced DNA damage, numerous recent studies focused on ionization and fragmentation of DNA building blocks upon irradiation with slow electrons, photons and ions. In their pioneering studies, Sanche and co-workers showed that low-energy (secondary) electrons can cause single-and doublestrand breaks of plasmid DNA. [4,5] Huels and coworkers investigated interactions of hyperthermal ions with DNA building blocks and concluded that heavy ions have the potential to induce particularly complex damage to DNA in the Bragg peak region. [6] Ionization and fragmentation of 2-deoxy-d-ribose (dR, C 5 H 10 O 4 ) molecules upon impact of keV and sub-keV ions has recently been investigated for isolated molecules [7] as well as for the condensed phase. [6] In both studies, almost complete disintegration of the molecule was observed and it was concluded that direct ion-induced DNA damage-for example in heavy ion or proton therapy of malignant tumors-may be dominated by deoxyribose fragmentation. Furthermore, Deng and coworkers have recently reported evidence for reactive scattering damage of 2-deoxy-d-ribose thin films by hyperthermal ions. [8,9] In the gas-phase studies, the mass spectrum of the fragment ions largely follows a power-law distribution with a characteristic exponent t of the order of 2, depending on the ion velocity, charge state and the atomic number of the impinging ion. From this, it was concluded that the fragmentation is to a large extent statistical. t was found to be an ideal parameter for the quantification of damage inflicted upon a molecule whose fragmentation yield is very close to 100 %, [7] but this quantification was purely phenomenological, since the fragmentation channels and the characteristic exponent could not be directly related to the amount of energy initially deposited into the deoxyribose molecules. In a study on MeV Si q + collisions with C 60 , Itoh et al. have already concluded that t carries information about the...

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Fragment ion distribution in charge-changing collisions of 2-MeV Si ions withC60

Cited by 16 publications

References 36 publications

Tight-binding molecular dynamics simulations of radiation-induced fragmentation ofC60

Tight-binding molecular dynamics simulations of radiation-induced fragmentation ofC60

Radiation-induced fragmentation of fullerenes

Precise Determination of 2‐Deoxy‐D‐Ribose Internal Energies after keV Proton Collisions

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