Source of atoms

All the work involved in astrophysical reflection aims to give meaning to the word star . It turns out that the description of stellar evolution complies with known physical theories and nuclear processes. 

Everywhere in the Universe the same patterns reappear atoms in the microcosm and stars in the macrocosm. Atoms and stars are related, for the star is the mother of atoms. This statement sums up one of the great discoveries of the twentieth century. The task of nuclear astrophysics is to draw in the details of the relationship. The creation of matter has become a subject of scientific research. The source of most atoms, or rather their nuclei, is the stars. 

The star bums its own ashes, and the ashes of its ashes, but iron will not bum and the nuclear fire goes out. Blue giants with collapsed cores open like flowers and scatter their swarms of winged atoms in the sky. The dying of their light is acknowledged with the cry of Supernova  

The study of the synthesis of atomic nuclei via nuclear reactions which proliferate in certain hot objects or violent astronomical events may well appear 

The planets do not feature amongst these sites. It has become totally unreasonable to attribute the paternity of quicksilver (mercury) to the planet Mercury, to associate iron with the red planet Mars, and lead with Saturn. We know today that iron, lead and mercury come from supernovas. 

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After a bake-out of 600—700 K, the bulk phase is likely to far exceed the surface phase as a source of atomic (molecular) impurities that desorb iato the gas phase (28). Bake-out at 1300 K gready reduces bulk-phase impurities. 

In DC sputtering, the plasma is formed between a metal target which acts as the source of atoms, and which is held at a negative potential with respect to the condensation substrate, which may be a metal or an insulator. The source... 

In most circumstances, it can be assumed diat die gas-solid reaction proceeds more rapidly diaii die gaseous transport, and dierefore diat local equilibrium exists between die solid and gaseous components at die source and sink. This implies diat die extent and direction of die transport reaction at each end of die temperature gradient may be assessed solely from diermodynamic data, and diat die rate of uansport across die interface between die gas and die solid phases, at bodi reactant and product sites, is not rate-determining. Transport of die gaseous species between die source of atoms and die sink where deposition takes place is die rate-determining process. 

Caseous uranium hexafluoride is important in the preparation of uranium as a source of atomic energy. ... 

C. W. Allen, Astrophysical Quantities (AQ), Athlone Press, London 1981, is an invaluable, concise and instructive source of atomic and astronomical data and formulae. 

W.C. Martin, Sources of Atomic Spectroscopy Data for Astrophysics , in PL. Smith and W. L. Wiese (eds.), Atomic and Molecular Data for Space Astronomy Needs, Analysis and Availability, Springer, Berlin, 1992. 

The decompositions of C302, CO, C02, CS2, COS, CSe2 and COSe are dealt with in this section. Apart from carbon suboxide, this is a group of stable, un-reactive compounds. Considerable emphasis has been placed on the investigation of the photolytic decompositions of some of these compounds which are thought to provide useful sources of atoms (C, O, S and Se) and free radicals (C20). The photochemistry of carbon dioxide has particular relevance to the chemistry of planetary atmospheres, although to date the mechanism of C02 photolysis remains obscure. 

One can draw the further conclusion that the product concentrations are also functions only of temperature, pressure, and the C/H/O ratio and not the original source of atoms. Thus, for any C—H—O system, the products will be the same i.e., they will be C02, H20, and their dissociated products. The dissociation reactions listed earlier give some of the possible new products. A more complete list would be... 

Flash pyrolysis of l,4-bis(tetrazol-5-yl)benzene at 600°C has been explored as a possible route to the dicarbene, CH-C( H4-CH . The product was phenylethyne which carried a C label from the tetrazole C-5, confirming that a CgH, species had been generated <87JA2534>. Thermal degradation of C-labelled 5-diazotetrazole has provided a source of atomic carbon for carbene reactions... 

In 1974, Cicerone and Stolarski suggested that if there were sources of atomic chlorine in the stratosphere, the following catalytic ozone destruction cycle... 

Zetzsch, C and W. Behnke, Heterogeneous Photochemical Sources of Atomic Chlorine in the Troposphere, Ber. Bunsenges. Phys. Chem., 96, 488-493 (1992). 

Thermal degradation of 13C labeled 5-diazotetrazole (32) provides a source of atomic carbon for the investigation of its carbene reaction (79JA1301). 

Consider two-dimensional anisotropic diffusion in an infinite thin film where the initial condition consists of a point source of atoms located at x = 2 = 0. The diffusivity tensor D, in arbitrary units, in the (2 1, 2) coordinate system is... 

When the dislocation acts as a sink for a flux of diffusing vacancies (or alternatively, as a source of atoms) or as a source for a flux of vacancies, it is useful to introduce a source or sink efficiency, 77, defined by... 

Suppose that the plane A is the bisector between the source of atoms and their sink (i.e.. the sources and sinks listed in Table 16.1). The component of diffusion... 

Heterogeneous reactions on the surface of seasalt aerosols have been suggested as a potential source of atomic chlorine in the marine boundary layer [10,105]. The tropospheric relevance of the reaction of nitrogen oxide species N203 with Nad and NaBr was demonstrated in a smog chamber experiment on dry and deliquiescent NaCl aerosol and on salt solutions [74,78,106,107] ... 

The basic source of atomic oxygen is the photosynthesis of plants, whose equation has the form ... 

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