Secondary ion emission dynamics model: A tool for nuclear track analysis

Iza, Peter; Farenzena, L. S.; Jalowy, T.; Groeneveld, K. O.; Silveira, E.F. da

doi:10.1016/j.nimb.2005.11.080

Cited by 20 publications

(14 citation statements)

References 19 publications

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“…When a cosmic-ray particle passes through the grain, it causes ionization, which probably is the major cause of molecule destruction (Iza et al 2006). A heated cylinder forms, and the heat is then dissipated across the grain (Leger et al 1985).…”

Section: Cosmic-ray Induced Dissociationmentioning

confidence: 99%

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Kalvāns

2014

A&A

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Context. Cosmic ray particles that hit interstellar grains in dark molecular cores may induce whole-grain heating. The high temperature of a CR-heated grain allows energy barriers for bulk diffusion and reactions to be overcome. Additionally, ice molecules are destroyed by direct cosmic-ray induced dissociation. Aims. We provide a justified estimate of the significance of cosmic-ray induced surface-mantle diffusion, chemical reactions in ice, and dissociation of ice species in a star-forming interstellar cloud core. Methods. We considered a gas clump in a collapsing low-mass prestellar core and during the initial stages of protostellar envelope heating with a three-phase chemical kinetics model. The model includes a proper treatment of the stochastic aspect of whole-grain heating and new experimental data for dissociation. Results. We found that the cosmic-ray-induced effects are mostly limited to an increase in abundance for carbon-chain species. The effect on major species' abundances is a few percentage points at most. The HNC:HCN ice abundance ratio in ice is increased. Conclusions. Among the processes considered in the model, dissociation is probably the most significant, while diffusion and reactions on warm grains are less important. All three processes facilitate the synthesis of complex molecules, including organic species.

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Section: Cosmic-ray Induced Dissociationmentioning

confidence: 99%

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Kalvāns

2014

A&A

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“…7c). Following Iza et al (2006), the sputtering occurs mainly due to long-lived repulsive electronic excitation that leads to atomic or molecular motion.…”

Section: Astrophysical Implicationmentioning

confidence: 99%

Radiolysis of ammonia-containing ices by energetic, heavy, and highly charged ions inside dense astrophysical environments

Pilling

Duarte

Silveira³

et al. 2010

A&A

129

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Deep inside dense molecular clouds and protostellar disks, interstellar ices are protected from stellar energetic UV photons. However, X-rays and energetic cosmic rays can penetrate inside these regions triggering chemical reactions, molecular dissociation, and evaporation processes. We present experimental studies of the interaction of heavy, highly charged, and energetic ions (46 MeV 58 Ni 13+ ) with ammonia-containing ices H 2 O:NH 3 (1:0.5) and H 2 O:NH 3 :CO (1:0.6:0.4) in an attempt to simulate the physical chemistry induced by heavy-ion cosmic rays inside dense astrophysical environments. The measurements were performed inside a high vacuum chamber coupled to the IRRSUD (IR radiation SUD) beamline at the heavy-ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France. The gas samples were deposited onto a polished CsI substrate previously cooled to 13 K. In-situ analysis was performed by a Fourier transform infrared spectrometer (FTIR) at different fluences. The average values of the dissociation cross-section of water, ammonia, and carbon monoxide due to heavy-ion cosmic ray analogs are ∼2 × 10 −13 , 1.4 × 10 −13 , and 1.9 × 10 −13 cm 2 , respectively. In the presence of a typical heavy cosmic ray field, the estimated half life of the studied species is 2-3 × 10 6 years. The ice compaction (micropore collapse) produced by heavy cosmic rays seems to be at least 3 orders of magnitude higher than that produced by (0.8 MeV) protons. The infrared spectra of the irradiated ice samples exhibit lines of several new species including HNCO, N 2 O, OCN − , and NH + 4 . In the case of the irradiated H 2 O:NH 3 :CO ice, the infrared spectrum at room temperature contains five bands that are tentatively assigned to vibration modes of the zwitterionic glycine (NH + 3 CH 2 COO − ).

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“…Since the impact of 52 MeV Ni atoms lies in the electronic energy-loss domain (projectile velocity > ∼ 0.01 cm μs −1 ) most of the deposited energy leads to excitation/ionization of target electrons (electronic energy loss regime). In turn, the electrons liberated from the ion track core (0.3 nm of diameter for 52 MeV Ni atoms; Iza et al 2006), transfer their energy to the surrounding condensed molecules (∼3 nm). The re-neutralization of the track proceeds concomitantly with the local temperature rise, leading to a possible sublimation.…”

Section: Dissociation Cross Sectionmentioning

confidence: 99%

Radiolysis of H₂O:CO₂ices by heavy energetic cosmic ray analogs

Pilling

Duarte²,

Domaracka

et al. 2010

A&A

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An experimental study of the interaction of heavy, highly charged, and energetic ions (52 MeV 58 Ni 13+ ) with pure H 2 O, pure CO 2 and mixed H 2 O:CO 2 astrophysical ice analogs is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by heavy cosmic rays inside dense and cold astrophysical environments, such as molecular clouds or protostellar clouds. The measurements were performed at the heavy ion accelerator GANIL (Grand Accélérateur National d'Ions Lourds in Caen, France). The gas samples were deposited onto a CsI substrate at 13 K. In-situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified. The dissociation cross sections of pure H 2 O and CO 2 ices are 1.1 and 1.9 ×10 −13 cm 2 , respectively. For mixed H 2 O:CO 2 (10:1), the dissociation cross sections of both species are about 1 × 10 −13 cm 2 . The measured sputtering yield of pure CO 2 ice is 2.2 × 10 4 molec ion −1 . After a fluence of 2−3 × 10 12 ions cm −2 , the CO 2 /CO ratio becomes roughly constant (∼0.1), independent of the initial CO 2 /H 2 O ratio. A similar behavior is observed for the H 2 O 2 /H 2 O ratio, which stabilizes at 0.01, independent of the initial H 2 O column density or relative abundance.

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Secondary ion emission dynamics model: A tool for nuclear track analysis

Cited by 20 publications

References 19 publications

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Radiolysis of ammonia-containing ices by energetic, heavy, and highly charged ions inside dense astrophysical environments

Radiolysis of H₂O:CO₂ices by heavy energetic cosmic ray analogs

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Secondary ion emission dynamics model: A tool for nuclear track analysis

Cited by 20 publications

References 19 publications

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Cosmic-ray-induced dissociation and reactions in warm interstellar ices

Radiolysis of ammonia-containing ices by energetic, heavy, and highly charged ions inside dense astrophysical environments

Radiolysis of H2O:CO2ices by heavy energetic cosmic ray analogs

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Product

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Radiolysis of H₂O:CO₂ices by heavy energetic cosmic ray analogs