Isotopes, properties

This group is made up of a very few individual inclusions found among Allende studies. In fact it can be reduced to the two most striking samples Cl and EK141. EK141 is unique in its isotopic properties, whereas a number of inclusions are closely related to C1 in their isotopic compositions (Papanastassiou and Brigham 1989 Loss et al. 1994). The discussion will therefore be limited to these two particular objects. Cl and EK141 have very similar... 

Ott U (1993) Physical and isotopic properties of surviving interstellar carbon phases. In Protostars Planets III. Levy Hand Lunine JI (eds) University of Arizona Press, Tucson, p 883-902 Ott U (1996) Interstellar diamond xenon and timescales of supernova ejecta. Astrophys J 463 344-348 Ott U, Begemann F, Yang J, Epstein S (1988) S-process krypton of variable isotopic composition in the Murchison meteorite. Nature 332 700-702... 

As shown by Marechal et al. (1999), the linearity property of the isotopic array formed in log-log plots by all the measurements of a same solution can be used to obtain the isotopic ratio of a sample with respect to the same ratio in a standard solution of known isotopic properties of a different element. Combining either Equations (21) or (22) for both the sample and the standard, we obtain ... 

This book is tailored to be your guide to mass spectrometry - from the first steps to your daily work in research. Starting from the very principles of gas phase ion chemistry and isotopic properties, it leads through design of mass analyzers, mass... 

Sakai H. (1968). Isotopic properties of sulfnr compounds in hydrothermal processes. Geochem. J, 2 29-49. 

To explain this different fractionation behavior, Taube (1954) postulated different isotope effects between the isotopic properties of water in the hydration sphere of the cation and the remaining bulk water. The hydration sphere is highly ordered, whereas the outer layer is poorly ordered. The relative sizes of the two layers are dependent upon the magnitude of the electric field around the dissolved ions. The strength of the interaction between the dissolved ion and water molecules is also dependent upon the atomic mass of the atom to which the ion is bonded. 

Symbol Cf atomic number 98 atomic weight 251 (the principal isotope) californium is a transuranium radioactive actinide element electron configuration [Rn]5/i°7s2 valence state +3 most stable isotope Cf, half-life 800 years isotope properties are presented below ... 

Sulphur isotopes (32,33,34,36S) fractionate strongly in the earth s crust because (1) the element occurs in different oxidation states with differential preference for heavy isotopes, (2) the existence of volatile and easily soluble compounds favors kinetic separations, and (3) it is involved in biogenic cycles where the oxidation state is easily changed and kinetic processes are important. From theoretical calculations of Bigeleisen (1961) and data on the isotopic properties of sulphur compounds by Sakai (1957, 1968), the amount of S isotope fractionation and its temperature dependence is known. The information on experimental inorganic isotope fractionation in coexisting sulphide minerals which occur naturally was summarized by Thode (1970), who also discussed the application of S isotopes from sulphides for geo thermometry (cf. also Sakai, 1971). Analytical work on all types of sulphur compounds which occur in nature has been reviewed by Nielsen (1973). 

Sakai, H. Isotopic properties of sulfur compounds in hydrothermal processes. Geochemical J. 2, 29-49 (1968). 

Secondly, the isotopic properties [5] of the nuclei of interest might not be suitable... 

Hoppe P., Strebel R., Eberhardt P., Amari S., and Lewis R. S. (2000) Isotopic properties of silicon carbide X grains from the Murchison meteorite in the size range 0.5—1.5 p,m. Meteorit. Planet. Sci. 35, 1157-1176. 

Conventionally, a chondrite group is defined as having a minimum of five unpaired chondrites of similar mineralogy, petrography, bulk isotopic properties, and bulk chemical compositions in major, nonvolatile elements. According to this definition, K chondrites could be considered as a grouplet there are only two known K chondrites (see K (Kakangari-like) chondrites). 

Figure 9 A type B1 inclusion from the Allende CVS chondrite. This centimeter-sized marhle consists mainly of melilite (bluish-white), titanium-aluminum-rich calcic pyroxene (bright colors), and anorthite and spinel (not readily visible in photo). Type B1 inclusions figure prominently in the early petrologic, trace element, and isotopic studies of CAIs, in part because of the richness of information about physicochemical histories available from petrologic, chemical and isotopic properties. Ironically, because type B inclusions occur only in CVS chondrites, they are nonrepresentative of CAIs in general. Photograph taken in cross-polarized transmitted fight. The colors are not the true colors of the crystals they are artifacts of the polarized fight.

The hibonite-pyroxene and hibonite-glass spherules are important because they represent a rare example of isotopic properties correlating with CAl mineralogy and bulk composition. Many... 

Wasserburg et al. (1977) defined a class of CAIs that have unusual isotopic properties even relative to other CAIs these were named FUN CAIs in reference to their Fractionation and Unidentified Nuclear effects. The characteristic signatures included httle or no excess of Mg... 

A hallmark of the two prototypical FUN inclusions (whose individual names are Cl and EK-1-4-1) is that their only distinguishing characteristics are their isotopic compositions. In all other properties they are identical to normal type B CAIs. To this day it remains tme that there is no certain way to recognize a FUN CAI except by isotopic analysis. For example, the FUN inclusion AXCAI-2271 from Axtell (Srinivasan et al, 2000), shown in Figure 15, is a compact type A (melilite-rich) CAI whose ordinary appearance gives no hint of its peculiar isotopic properties. Nevertheless, certain kinds of CAIs do have a statistical propensity toward unusual isotopic properties. FoBs are relatively rare, yet four of them possess large degrees of mass-dependent isotopic fractionation (Clayton et al., 1984 Davis et al, 1991 MacPherson and Davis, 1992)... 

The origin of mass-dependent isotopic fractionation in FUN CAIs is commonly (and somewhat casually) assumed to be the result of Rayleigh-type distillation, while the inclusions were molten. It is true that a strong case for distillation has been made in the case of the so-called HAL-type hibonites (see Section 1.08.7), based on trace element and isotopic properties (Lee et al, 1979, 1980 Davis et al, 1982 Ireland et al, 1992 Floss et al, 1996). Such an origin is problematic for other FUN CAIs, however, especially those that are otherwise identical in bulk composition to non-FUN CAIs. Most notably this is true of the FoBs that also happen to have F or FUN properties (Clayton et al, 1984 Davis et al, 1991). These objects are magnesium-rich relative to other CAIs, yet distillation experiments conducted on chondritic starting materials consistently show that... 

Figure 15 Backscattered electron image of a FUN CAI from the Axtell CV3 chondrite. Except for its isotopic properties, this object is an ordinary t)fpe A CAI (photo courtesy of Dr. Gary Huss, Arizona State University after Srinivasan et al, 2000). Abbreviations as used previously.

CR clan chondrites. The CR clan includes a wide diversity of chondritic meteorites that share sufficient mineralogic and isotopic properties in common to be considered genetically related (Weisberg et al, 1995) it includes the CR and... 

CAS 7440-58-6. Hf. Metallic element of atomic number 72, Group IVB of the periodic table, aw 178.49, valences of 2, 3, 4 6 stable isotopes. Properties Generally similar to zirconium. Gray crystals. D13.1, mp approximately 2150C, bp above... 

The geochemical behavior and chemical and isotopic properties of natural waters are related to their location in the hydrosphere, that is, as precipitation, stream flow, soil water, groundwater, ocean water, etc. A goal of this section is to make the reader aware of the unique and different chemical and isotopic properties of each of these waters and explain why their chemistries differ. 

TABLE 8.2 Contrast between some chemical and isotopic properties of artesian (confined) and water-table (unconfined) groundwaters... 

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