Solar materials

K. This mass of rocky material probably formed the nucleus for condensation and attracted large amounts of the H2/He-rich solar material around 4.5 billion years ago, acting as a galactic vacuum cleaner. 

Yin QZ, Jacobsen SB, Yamashita K (2002) Diverse supernova sources of pre-solar material inferred from molybdenum isotopes in meteorites. Nature 415 881-883 Young ED, Galy A, Nagahara H (2001) Kinetic and equilibrium mass-dependent isotope fractionation laws in nature and their geochemical and cosmochemical significance. Geochim Cosmochim Acta 66 1095-1104... 

Isotope variations found in extraterrestrial materials have been classified according to different processes such as chemical mass fractionation, nuclear reactions, nucleosynthesis, and/or to different sources such as interplanetary dust, solar materials, and comet material. Various geochemical fingerprints point to the reservoir from which the planetary sample was derived and the environment in which the sample has formed. They can be attributed to a variety of processes, ranging from heterogeneities in the early solar nebula to the evolution of a planetary body. For more details the reader is referred to reviews of Thiemens (1988), Clayton (1993, 2004), and McKeegan and Leshin (2001). 

Hydrogen fusion via either the proton-proton chain or the CNO cycle in the centre of stars comes to an end when most of the hydrogen has been transformed into helium. Helium fusion produces two elements essential to life, namely carbon and oxygen. In fact, carbon constitutes 18% of our bodies, and oxygen 65%, whilst the fractions of these same elements in solar material are just 0.39% and 0.85%, respectively. Only hydrogen and helium are more abundant in the Sun. 

Barshay, S. S. and Lewis, J. S. (1976) Chemistry of primitive solar material. Annual Reviews of Astronomy and Astrophysics, 14, 81-94. 

An overview of the most important phenomena in interface science related to studying solar materials is presented in this section. The methods for characterizing interfaces and those deemed likely to have the largest near-term impact on solving the problems of interface degradation are then mentioned. 

The three phases of interest are the solid (S), liquid (L), and gas (G) phases, none of which is infinite. The boundary region between the S, L, and G phases has fundamentally different properties from the bulk. The S/S, S/G, and S/L surfaces, in that order, are of greatest interest to the solar materials scientist (4). Some of the broad topical areas of study at the interfaces of SECS are listed in Table 2. An understanding of these topics is enhanced by applying the methodologies of interface science. 

The experimental methods deemed most appropriate for studying solar materials have been considered in some detail (1-4). Briefly, these include using polycrystalline materials and methods that permit direct examination. 

The cost-effective deployment of large areas of solar collectors will most probably be polycrystalline materials, with all index planes emerging at the surface. Therefore, it is not expected that the structural determination of solar materials surfaces will be applied except for a few special cases. However, determining S/S inter facial structures is important, as shown by Figs. 6-9 in Ref. 2. The challenge in solar interface research will be to understand the changes in surface activity of heterogeneous real surfaces and interfaces. Here, SEM and possibly STEM techniques should be used extensively. 

In this section, an overview will be provided of the topical areas of surface science research that are especially important to solar energy technologies. These comments are based in part on a report from a workshop held in July 1980 (4). Broad areas of surface science that affect solar materials research are indicated. 

Table 1 of a paper by Murr (2) lists problems and/or concerns related to specific interface materials and specific components of SECS. In Table 2 of the same work, he related topical study areas and/or research problems to S/S, S/L, S/G, L/L, and L/G interfaces. It is also useful to divide interface science into specific topical areas of study and consider how these will apply to interfaces in solar materials. These study areas are thin films grain, phase, and interfacial boundaries oxidation and corrosion adhesion semiconductors surface processes, chemisorption, and catalysis abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. The actual or potential solar applications, research issues and/or concerns, and needs and opportunities are presented in the proceedings of a recent Workshop (4) and summarized in a recent review (3). 

Table 4. Some Current Problems with Solar Materials...

Die K/Rb-Verhaltnisse chemisch vergleichbarer Gesteine liegen im Bereich der Tektite das spricht fiir die Herkunft der Tektite aus irdi-scher, zumindest solarer Materie. 

Bob nods. Some prominences erupt, spewing enormous amounts of solar material into space. The most violent of solar eruptions is a coronal mass ejec-... 

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