Ion implantation effects in “cosmic” dust grains

doi:10.1016/0012-821X(74)90083-1

Earth and Planetary Science Letters

Volume 22, Issue 3, June 1974, Pages 205-214

https://doi.org/10.1016/0012-821X(74)90083-1 Get rights and content

Abstract

Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering. The present results have implications concerning the origin of small molecules in interstellar or circumstellar clouds, the “aging” of cosmic dust grains in space, and the “sticking” process in the solar nebula.

References (24)

BibringJ.P. et al.
Lunar Soil maturation
J.P. Bibring, A.L. Burlingame, J. Chaumont, Y. Langevin, M. Maurette and P.C. Wszolek, Simulation of lunar carbon...
BibringJ.P. et al.
Ultra-thin amorphous coatings on lunar dust grains
Science
(1972)
BibringJ.P. et al.
Solar wind and lunar wind microscopic effects in the lunar regolith (abs.)
WinterbonK.B. et al.
Spatial distribution of energy deposited by atomic particles in elastic collisions
Math. Fys. Medd.
(1970)
BameS.T.
Spacecraft observations of the solar wind composition
EberhardtP. et al.
Trapped solar wind noble gases, exposure age and K/Ar age in Apollo 11 lunar fine material
DranJ.C. et al.
Track metamorphism in extraterrestrial breccias
Geochim. Cosmochim. Acta
(1972)
SpinradH. et al.
Infrared spectra of stars
Ann. Rev. Astron. Astrophys.
(1969)
BorgJ. et al.
Nuclear particle track studies in the lunar regolith: some new trends and speculations

AannestadP.A.

Molecule formation II, In interstellar shock waves

Ap. J. Suppl.

(1973)

LinC.C.

Theory of spiral structure

Highlights of Astronomy

(1971)

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The solar wind is a possible source for hydrogen and other volatiles on planetary bodies. To better understand the role of the solar wind during the volatile acquisition of planetary materials, we conducted hydrogen implantation experiments on olivine, orthopyroxene, quartz single crystals. Depth profiles of hydrogen concentration after implantation are determined by the Nuclear Resonance Reaction Analysis. We find that energetic hydrogen particles penetrate into the sample and accumulate at a certain depth. The hydrogen concentration increases with the hydrogen fluence until a “saturation level” is attained. Hydrogen saturation level (e.g., ∼10–20 at.% in olivine, equivalent to 0.5–1.2 wt%) far exceeds the equilibrium solubility in the bulk crystal at a similar thermodynamic condition (∼10⁻²² wt%). The results of olivine show that the hydrogen penetration depth increases whereas the saturation level decreases (weakly) with the beam energy. Hydrogen saturation level also depends on the mineral species in the order: olivine > orthopyroxene > quartz. The experimental results can be applied to explain some observations on the high surface water content of some planetary bodies including Itokawa asteroid and the Moon. We also explore the possibility of hydrogenated dusts by the solar wind implantation as a source for water on terrestrial planets. We conclude that if all dusts were exposed to the solar wind and all implanted hydrogen were converted to water, then >10 ocean masses would have been acquired for Earth by ∼100 years. However, the main part of the proto-planetary disk was not exposed to the solar wind and dusts could have been hydrogenated only when they were far from the equatorial plane of the disk. We discuss a possible mechanism to transport the hydrogenated dusts to the disk interior via turbulent mixing. Also, our experimental results and the mass dependence of the particle energies in the solar wind suggest that the D/H ratio of the dusts exposed to the solar wind will be higher than the solar wind value.
Deuteration of molecular clumps induced by cosmic rays
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The D/H ratio in astrophysical environments has instigated the scientists for at least 50 years. The wide range of values in the interstellar medium (ISM) from 10e to 7 to 10e-1 have usually been claimed to be due to small zero-point energy differences between reactants and products involving D and H (mainly at low temperatures). Here, we present a new source of deuteration processes in the ISM clouds as a result of cosmic ray irradiation. As a study object, we consider a typical molecular clump under the presence of incoming cosmic rays simulated computationally. The calculations were performed employing the Monte Carlo toolkit GEANT4 code (considering hadronic physics) and considering mainly the proton and alpha component of the incoming cosmic rays from the ISM (the dominant ones for the production of secondary protons and deuterons). The results suggest an increasing D/H ratio as function of time in the central part of molecular clumps (<200 AU) with the largest deuteration in the central region of the cloud, and a bump in the D/H ratio around 2–10 AU (which becomes more pronounced for clouds with larger timescales; > 10 Myrs). The results also show that for timescales between 10 and 100 Myrs the central part of the cloud has D/H around 6-16e-3, a value compatible with the observed D/H in some interstellar clouds. This work adds a new piece to the D/H puzzle of the ISM and might also help to explain the D/H ratio measured in different objects inside the Solar system.
Space weathering and the low sulfur abundance of Eros
2005, Icarus
Citation Excerpt :
This is probably due to both the higher energy of the He+ ions and the fact that each ion–atom collision can transfer a larger amount of energy. A similar conclusion has been reached by Bibring et al. (1974) and Maurette and Price (1975) who report that He+ is ∼100 times more efficient that H+ in producing macroscopically visible changes in mineral grains. Since sputtering is not a classical process, a “billiard ball” analysis is only a very rough approximation, but it nonetheless indicates that a 4 kV He+ ion transfers some 12–15 times as much energy onto a target atom of mass ⩾16 as a 1 kV H+ ion.
The surprisingly low S/Si ratio of Asteroid 433 Eros measured by the NEAR Shoemaker spacecraft probably reflects a surface depletion rather than a bulk property of the asteroid. The sulfur X-ray signal originates at a depth $< 10 μm$ in the regolith. The most efficient process for vaporizing minerals at the heliocentric distance of Eros are sputtering by solar wind ions and hypervelocity impacts. These are the same processes that account for the changes in optical properties of asteroids attributed to “space weathering” of lunar surface materials, although the relative importance of sputtering and impacts need not be the same for the Moon and asteroids. Troilite, FeS, which is the most important sulfide mineral in meteorites, and presumably on S-type asteroids like Eros, can be vaporized by much less energy than other major minerals, and will therefore be preferentially lost. Within 10⁶ years either process can remove sulfide from the top 10–100 μm of regolith. Sulfur will be lost into space and some sulfur will migrate to deeper regolith layers. We also consider other possible mechanisms of surficial sulfur depletion, such as mineral segregation in the regolith and perhaps even incipient melting. Although we consider solar wind sputtering the most likely cause of the sulfur depletion on Eros, we cannot entirely rule out other processes as causes of the sulfur deficiency. Laboratory simulations of the relevant processes can address some of the open questions. Simulations will have to be carried out in such a way that potential sulfur loss processes as well as resurfacing can be studied simultaneously, requiring a large and complex environmental chamber.
Isotopic composition of surface-correlated chromium in Apollo 16 lunar soils
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We have analyzed by thermal ionization mass spectrometry (TIMS) the isotopic composition of Cr in five progressive etches of size-sorted plagioclase grains separated from lunar soils 60601 and 62281. Aliquots of the etch solutions were spiked for isotopic dilution (ID) analysis of Cr and Ca. The Ca ID data indicate that the initial etch steps represent dissolution of an average 0.1 to 0.2 μm depth from the grain surfaces, the approximate depth expected for implanted solar wind. The Cr/Ca ratio in the initial etches is several fold higher than that expected for bulk plagioclase composition, but in subsequent etches decreases to approach the bulk value. This indicates a source of Cr extrinsic to the plagioclase grains, surface-correlated and resident in the outermost fraction of a μm, which we provisionally identify as solar wind Cr. The surface-correlated Cr is isotopically anomalous and by conventional TIMS data reduction has approximately 1 permil excess ⁵⁴Cr and half as great excess ⁵³Cr. In successive etches, as the Cr/Ca ratio decreases and approaches the bulk plagioclase value, the magnitude of the apparent anomalies decreases approaching normal composition. If these results do indeed characterize the solar wind, then either the solar wind is enriched in Cr due to spallation in the solar atmosphere, or the Earth and the various parent bodies of the meteorites are isotopically distinct from the Sun and must have formed from slightly different mixes of presolar materials. Alternative interpretations include the possibility that the anomalous Cr is meteoritic rather than solar or that the observed (solar) Cr is normal except for a small admixture of spallation Cr generated on the Moon. We consider these latter possibilities less likely than the solar wind interpretation. However, they cannot be eliminated and remain working hypotheses.
Experiments on thermal release of implanted noble gases from minerals and their implications for noble gases in lunar soil grains
1993, Geochimica et Cosmochimica Acta
Experiments on ion implantation were performed in order to study the release mechanisms of solar particles from lunar soil grains. Helium, neon, and argon ions were implanted into olivine and ilmenite. The release temperatures of noble gases were investigated by heating samples stepwise; the results show that they depend on irradiation energy and dose. We conclude that the release temperature is related to the size of bubbles in which noble gases are trapped: Noble gases in small and large bubbles are released at 400–600°C and 800–1200°C, respectively. In Ne and Ar implantation experiments into olivine, a component was released during recrystallization of amorphized surfaces. Based on these experimental results, we suggest that components released from lunar ilmenite grains at different temperatures would correspond to solar particles of different energies. We also suggest that He and Ne of solar wind energy (about 1 keV/amu) should be retained in lunar ilmenite grains, while they should be lost from olivine grains.
Non-equilibrium chemistry in space
1992, Nuclear Inst. and Methods in Physics Research, B
Chemical processes by accelerated species do not proceed in thermal equilibrium with the target molecules. The hot or suprathermal reactions are characterized by the fact that a kinetic energy ranging from about 1 to few 10 eV is imparted to the collision complex. Reaction rates are by orders of magnitude higher and products are more diversified than in classic thermally controlled reactions. Space is rich in energetic atoms, ions, molecules, fragments, clusters, and grains from cosmic rays, solar or stellar radiation, shock waves and many secondary acceleration processes with energies ranging from a few eV (photodissociation) to some TeV (cosmic rays). Non-equilibrium chemistry is, thus, typical for space. Suprathermal reactions in the solid state can effectively compete with radiolysis or photolysis and ion molecule interactions, particularly in view of the formation of complex organic matter by multicenter reactions in the collision cascades.

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Ion implantation effects in “cosmic” dust grains

Abstract

Lunar Soil maturation

Ultra-thin amorphous coatings on lunar dust grains

Science

Solar wind and lunar wind microscopic effects in the lunar regolith (abs.)

Spatial distribution of energy deposited by atomic particles in elastic collisions

Math. Fys. Medd.

Spacecraft observations of the solar wind composition

Trapped solar wind noble gases, exposure age and K/Ar age in Apollo 11 lunar fine material

Track metamorphism in extraterrestrial breccias

Geochim. Cosmochim. Acta

Infrared spectra of stars

Ann. Rev. Astron. Astrophys.

Nuclear particle track studies in the lunar regolith: some new trends and speculations

Molecule formation II, In interstellar shock waves

Ap. J. Suppl.

Theory of spiral structure

Highlights of Astronomy