Low‐energy helium ion irradiation‐induced amorphization and chemical changes in olivine: Insights for silicate dust evolution in the interstellar medium

Carrez, Philippe; Demyk, K.; Cordier, Patrick; Gengembre, L.; Grimblot, J.; d’Hendecourt, Louis Le Sergeant; Jones, A. P.; Leroux, Hugues

doi:10.1111/j.1945-5100.2002.tb00814.x

Cited by 114 publications

(111 citation statements)

References 44 publications

(62 reference statements)

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“…The column of gas accelerated in such shocks, which corresponds to the irradiation fluence, is of the order of 10 16 -10 18 H + /cm 2 , for 5 to 250 nm radius-grains (Jones et al 1996). In this irradiation regime nuclear interactions with the target atoms are dominant and the grains can be amorphized as shown in various simulation experiments (Demyk et al 2001;Carrez et al 2002;Jäger et al 2003a;Brucato et al 2004;Djouadi et al 2005). In addition, the grain sizes are of the same order as the implantation range of the ions, leading to the complete amorphization of the grains.…”

Section: Introductionmentioning

confidence: 91%

“…Among the processes that could account for the disappearance of the crystalline silicates in the diffuse ISM, dust amorphization induced by ion irradiation in supernovae shock waves in the warm ISM appears to be the most efficient process as demonstrated by dedicated laboratory experiments (Demyk et al 2001;Carrez et al 2002;Demyk et al 2004). During the propagation of shock waves, the interstellar gas is ionized and the gas and dust acquire relative velocities leading to dust irradiation by gas, principally protons (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Hydroxyl radical production and storage in analogues of amorphous interstellar silicates: a possible “wet” accretion phase for inner telluric planets

Djouadi

Robert

d’Hendecourt

et al. 2011

A&A

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Context. Interstellar silicate grains are thought to be amorphized by interaction with high-and low-energy particle interactions in astrophysical environments. In addition, low energy (a few keV) particles will implant atoms within the grains. Aims. In this paper we experimentally investigate the consequence of the implantation of H + at low irradiation energies into analogues of interstellar silicate grains, and look for the formation of hydroxyl radicals within the silicate matrix. Methods. Thin amorphous silicate films (∼100 nm) were sequentially irradiated with H + ions at low energies (3.5, 2.5 and then 1.5 keV) ensuring an implantation of the ions through the full depth of the films. The fluences used, 3× 10 16 , 10 17 and 3× 10 17 H + /cm 2 , are compatible with those expected in shocks in the interstellar medium. We used infrared spectroscopy to monitor and quantify the OH band evolution after irradiation. In order to distinguish the newly formed OH groups from those originating from unavoidable atmospheric contamination, the D/H depth ratios were measured with a NanoSIMS ion microprobe.Results. An increase in the OH band strength in the infrared spectra after irradiation reveals the formation of OH bonds within the irradiated silicate thin films. NanoSIMS measurements of the D/H signature in the region of ion implantation show that the newlyformed OH groups make up about 40% of the observed OH band in the IR, the rest are due to an atmospheric hydroxylation of the sample. Only about 2% of the incident ions lead to OH bond formation and, at most, the irradiated silicates retain about 3% of the incident protons as OH groups within their structure. Conclusions. Our laboratory experimental simulations show a possible production and storage of hydroxyl radicals in amorphous laboratory silicates. In the astrophysical context, such OH radicals, strongly bonded to pre-accretion material, could constitute a non negligible reservoir of -OH, thus water. These experimental results allow us to revisit and reinstate the hypothesis of a possible "wet" accretion of the telluric planets early in the history of the formation of the Solar System.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Hydroxyl radical production and storage in analogues of amorphous interstellar silicates: a possible “wet” accretion phase for inner telluric planets

Djouadi

Robert

d’Hendecourt

et al. 2011

A&A

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“…However, the uncertainty on this parameter may be a factor of two and, for example, Wang et al (1999) assumed a displacement energy of E D ≈ 25 eV for similar forsterite-type materials. Experimental studies show that, under the effect of energetic ion irradiation, silicate grains become amorphous in structure (Demyk et al 2001;Carrez et al 2002) and so the displacement energy will be lower than for a crystalline structure. We therefore adopt a displacement energy of E D = 25 eV.…”

Section: Silicate Core Sputteringmentioning

confidence: 99%

A re-evaluation of dust processing in supernova shock waves

Bocchio

Jones

Slavin

2014

A&A

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107

154

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Context. There is a long-standing and large discrepancy between the timescale for dust formation around evolved stars and the rapid dust destruction timescale in interstellar shocks. Aims. We use our latest estimates for dust processing to re-evaluate the dust destruction efficiency in supernova triggered shock waves, estimate the dust lifetime, and calculate the emission and extinction from shocked dust. Methods. We modelled the sputtering and fragmentation of grains in interstellar shocks for shock velocities between 50 km s −1 and 200 km s −1 . We constrained the dust destruction using our recent dust model. Finally, we coupled our code to the DustEM code in order to estimate the emission and extinction from the dust post-shock. Results. Carbonaceous grains are quickly destroyed, even in a 50 km s −1 shock, leading to a shorter lifetime than in previous studies. Silicate grains appear to be more resilient, but the new destruction lifetime that we find is similar to previous studies and short compared to the dust injection timescale. Conclusions. The calculated fraction of elements locked in grains is not compatible with the observed values and therefore implies the re-formation of dust in the dense regions of the interstellar medium. Better modelling of the silicate sputtering together with hydrodynamical simulations of interstellar shocks, appears to reduce the silicate destruction and may close the destruction-formation timescale gap.

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“…Further, we require a quantity for how many displacements per lattice atom (dpa) are required to observe amorphization. We set this number to be 2.5 based on the mineral irradiation experiments for enstatite (Jäger et al 2003), forsterite (Bringa et al 2007) and olivine (Demyk et al 2001;Carrez et al 2002). However, this quantity remains inaccurate as most of the above cited studies determined doses for He-irradiation to fully amorphize the minerals varying within an order of magnitude.…”

Section: Calculation Of Dust Amorphizationmentioning

confidence: 99%

“…The destructive impact of high-energy irradiation on crystalline structures by ions has been demonstrated in laboratory measurements by, e.g., Jäger et al (2003), Bringa et al (2007), Demyk et al (2001), Carrez et al (2002), mainly for low energetic cosmic rays (E > ∼ 50 keV) but rarely also for lower energies typical of stellar winds.…”

Section: Introductionmentioning

confidence: 99%

Dust amorphization in protoplanetary disks

Glauser

Güdel

Watson

et al. 2009

A&A

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Aims. High-energy irradiation of circumstellar material might impact the structure and the composition of a protoplanetary disk and hence the process of planet formation. In this paper, we present a study of the possible influence of stellar irradiation, indicated by X-ray emission, on the crystalline structure of circumstellar dust. Methods. The dust crystallinity is measured for 42 class II T Tauri stars in the Taurus star-forming region using a decomposition fit of the 10 μm silicate feature, measured with the spitzer IRS instrument. Since the sample includes objects with disks of various evolutionary stages, we further confine the target selection, using the age of the objects as a selection parameter. Results. We correlate the X-ray luminosity and the X-ray hardness of the central object with the crystalline mass fraction of the circumstellar dust and find a significant anti-correlation for 20 objects within an age range of approx. 1 to 4.5 Myr. We postulate that X-rays represent the stellar activity and consequently the energetic ions of the stellar winds which interact with the circumstellar disk. We show that the fluxes around 1 AU and ion energies of the present solar wind are sufficient to amorphize the upper layer of dust grains very efficiently, leading to an observable reduction of the crystalline mass fraction of the circumstellar, sub-micron sized dust. This effect could also erase other relations between crystallinity and disk/star parameters such as age or spectral type.

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Low‐energy helium ion irradiation‐induced amorphization and chemical changes in olivine: Insights for silicate dust evolution in the interstellar medium

Cited by 114 publications

References 44 publications

Hydroxyl radical production and storage in analogues of amorphous interstellar silicates: a possible “wet” accretion phase for inner telluric planets

Hydroxyl radical production and storage in analogues of amorphous interstellar silicates: a possible “wet” accretion phase for inner telluric planets

A re-evaluation of dust processing in supernova shock waves

Dust amorphization in protoplanetary disks

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