Interplanetary dust particles carbonates

Rietmeijer, F. J. M. MacKinnon, I. D. R. 1987 Metastable carbon in two chondritic porous interplanetary dust particles. Nature, Land. 326, 162-165. 

Figure 13 A 5 jjim interplanetary dust particle. This is a carbon-rich particle with chondritic elemental composition. It is porous and entirely composed of anhydrous phases. This 10 ° g particle is an aggregate of >10 umelated and unequilibrated grains. The smooth grains are t5fpically single mineral grains such as Fo, En, or pyrrhotite or carbonaceous material, and the <0.5 p,m lumpy grains are usually GEMSs. This is a relatively t5fpical example of the particles that have entry speeds consistent with cometary origin.

Bradley J. P., Brownlee D. E., and Fraundorf P. (1984b) Carbon compounds in interplanetary dust particles evidence for formation by heterogeneous catalysis. Science 223, 56-58. 

Floss C. and Stadermann F. J. (2003) Complimentary carbon, nitrogen, and oxygen isotopic imaging of interplanetary dust particles presolar grains and an indication of a carbon isotope anomaly. In Lunar Planet. Sci. XXXIV, 1238. The Lunar and Planetary Institute, Houston (CD-ROM). 

Keller L. P., Thomas K. L., and McKay D. S. (1994) Carbon in primitive interplanetary dust particles. In Analysis of Interplanetary Dust, AIP Conf. Proc. 310... 

Most of interplanetary dust particles (IDPs) contain 2-10 % carbon by weight in a variety of physical forms, including amorphous materials with a minor amount of oxygen and nitrogen. Allamandola et al. [27] reported tliat both IDPs and meteorites might contain materials similar to PAHs. Clemett et al. [28] identified many PAHs and their alkylated derivatives in IDPs. 

PAHs are believed to be a major class of carbon-bearing molecules in the interstellar medium 1138], They are found in carbonaceous chondrites tliat have fallen to Earth (see section 4.2.1) and in interplanetary dust particles [28]. Shock and Schulte [139] suggested that amino acids could be syntliesized by aqueous alteration of precursor PAHs in carbonaceous chondrites. We directed attention to shock reaction of PAHs [135,140,141], and conducted shock reactions using benzene, tire simplest aromatic hydrocarbon, as a starting material to simulate possible reactions occurring in interstellar space. Furtliermore, we examined the mechanism of shock reaction on the basis of quantum chemistry and discussed the implication for cosmocheniistiy. 

The study of the effects induced by ion irradiation of solid materials, in particular solid carbons, is relevant in many fields of science and technology. Here we focus on its relevance in astrophysics. Solid carbon-bearing species are extremely abundant in space both in the gas and in the solid phases. A wide variety of solid carbons are observed in the interstellar and circumstellar medium as well as in many objects of the Solar System including those collected at or nearby Earth (interplanetary dust particles and meteorites). Observed and/or predicted carbon-bearing solids (or large molecules) include species with different hybridizations (sp, sp, sp" ) such as amorphous carbons, polycyclic aromatic hydrocarbons, fullerenes, nanodiamonds, graphite, and carbon chain molecules. The literature in the field is enormous interesting reviews can be found in a recent special volume of Speetroehimica Acta [1]. 

IDPs IPHAC ISM ITO interplanetary dust particles ion-produced hydrogenated amorphous carbon interstellar medium indium tin oxide... 

It is reported that 1,4-dibromonaphthalene can be formed selectively and in 90% yield by irradiation of naphthalene and 1-bromonaphthalene with stoichiometric amounts of bromine and with the minimum amount of CH2CI2 as solvent at —30 to — SO C. In contrast, l,2,3,4,5-pentabromo-l,2,3,4-tetrahyd-ronaphthalenes result from irradiation of 1-bromonaphthalene in CCI4 at — 30°C, whereas at 77°C only 1,5-dibromonaphthalene is formed and in 80% yield. Two of the more unusual examples of the photoinduced introduction of groups into aromatic rings which have been described within the year are the formation of 1-cyanopyrene in a yield of up to 73% from irradiation at the interface of a solution of pyrene and 1,4-dicyanobenzene in propylene carbonate and an aqueous solution of NaCN in a polymer microchannel chip, and the addition of a variety of groups e.g. NH2, OMe, CN, and CO2H) to coronene by irradiation of arene-ice mixtures at low temperature and pressure." The latter work provides the first experimental evidence that such functionalized arenes, which are detected in primitive meteorites and interplanetary dust particles, may have arisen, at least in part, from photochemistry in ice. 

Calculations also showed that about 4 Ga ago, more carbon was delivered to Earth in less than a few million years by interplanetary dust particles than the current amount of organic carbon in the biosphere, or about... 

The sizes of the cometary dust grains vary from less than a micron to probably several centimeters. Infrared observations near 10 pm show the silicate spectral features. In addition, there seems to be a black ingredient presumed to be carbon. Due to different accelerations from the solar radiation pressure, the larger particles follow the comet close in its orbit and are more concentrated to the orbital plane. They become sometimes visible in the anti-tails , narrow spikes which point towards the Sun by an effect of projection when the Earth crosses the comet s orbital plane. Non of the meteorites found so far on Earth seem to be of cometary origin. However, very fluffy micron sized interplanetary dust grains (Brownlee particles) which have been collected by high flying aircraft are possibly cometary debris. 

Meteorites from the asteroid belt are a potential source of some of the purine bases present in RNA. As asteroids travel in their orbits between Mars and Jupiter they collide with each other and pieces are broken off that vary in size from large bodies (potential meteorites) to dust particles. If the energy of the collision is great enough, this material is propelled out of its orbit into the interplanetary medium and some of the material eventually reaches the Earth. Approximately 10 kg of asteroidal material reached the primitive Earth s surface (6). This corresponds to a layer of material weighing 2x10 kg/m if spread uniformly over the surface of the Earth. The carbon content of the soluble organics present (1%) is equivalent to a layer of carbon compounds 25 m thick on the primitive Earth. Since meteorites contain about 1 ppm of purines and pyrimidines, then about lO kg of these compounds were on the primitive Earth. 

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