Natural isotopes

Oxygen has nine isotopes. Natural oxygen is a mixture of three isotopes. 

Isotope Natural abundance (%) Nuclear spin Electric quadrupole moment NMR frequency fora 23.5 kO field (MHz) Relative sensitivity... 

R. Krol SE and V. A, Grinenko (eds.). Stable Isotopes Natural and Anthropogenic Sulfur in the Environment, SCOPE Report 43. Wiley. Chichesier. 1991. 466 pp,... 

ISOTOPE NATURE NUMBER NUMBER COMPOSITION MASS CHARGE NEUTRAL ATOM... 

The atomic weight increases regularly across the row except for the inversion at cobalt and nickel. We would expect the atomic weight of Ni to be higher than that of Co because there are more protons (28) in the Ni nucleus than in the Co nucleus (27). The reason for the inversion lies in the distribution of naturally occurring isotopes. Natural cobalt consists entirely of the isotope 2 Co natural nickel consists primarily of the isotopes Ni and Ni, the 58-isotope being about three times as abundant as the 60-isotope. 

The results for all sites are given in Table 5.1, and are best considered by dividing sites into three groups according to isotopic nature of the matrix (i) sites with most isotopically emiched matrix carbonates (Die Kelders and Swartkrans), (ii) sites with rather less enriched carbonates (Klasies River Mouth and Makapansgat), and finally (iii) a site with depleted deposit values (Border Cave). This is summarized in Fig. 5.5. The division also fortuitously provides a range of age depths in two categories. As indicated in Table 5.1, many of these data have been published elsewhere, but the purpose for which they are considered in combination here has not been previously attempted. 

Cabana G, Rasmussen JB. 1994. Modelling food chain structure and contaminant bioaccumulation using stable nitrogen isotopes. Nature 372 255-257. 

Atom Isotope Natural abundance Monoisotopic Average mass mass ... 

Isotope Natural Abundance (% total carbon) Remarks... 

In the case of pharmaceutical solids that are dominated by carbon and proton nuclei, the dipole-dipole interactions may be simplified. The carbon and proton nuclei may be perceived as dilute and abundant based upon then-isotopic natural abundance, respectively (Table 1). Homonuclear 13C—13C dipolar interactions essentially do not exist because of the low concentration of 13C nuclei (natural abundance of 1.1%). On the other hand, H—13C dipolar interactions contribute significantly to the broad resonances, but this heteronuclear interaction may be removed through simple high-power proton decoupling fields, similar to solution-phase techniques. 

NMR active isotope Natural abundance Gyromagnetic ratio y fH = 100) Corresponding NMR inactive" isotope Natural abundance Gyromagnetic ratio y ( H=T00)... 

Element Isotope Natural abundance (%) or half-life Standard isotope ratio or energy... 

Spero HJ, Bijma J, Lea DW, Bemis BE (1997) Effect of seawater carbonate concentration on foraminiferal carbon and oxygen isotopes. Nature 390 497-500 Spivack AJ, Edmond JM (1986) Determination of boron isotope ratios by thermal ionization mass spectrometry of the dicesium metaborate cation. Anal Chem 58 31-35 Spivack AJ, Edmond JM (1987) Boron isotope exchange between seawater and the oceanic crust. Geochim Cosmochim Acta 51 1033-1043... 

Isotope Natural Atomic mass Spin Nuclear... 

Material Form Essential Element Desirable Isotope Natural Occurrence... 

Stable Isotopes Natural and Anthropogenic Sulphur in the Environment Krouse, H. R. Grinenko, V. A., Eds. Wiley Chichester, United Kingdom, 1991 p 440. 

Helium-4 Normal-Superfluid Transition Liquid helium has some unique and interesting properties, including a transition into a phase described as a superfluid. Unlike most materials where the isotopic nature of the atoms has little influence on the phase behavior, 4He and 3He have a very different phase behavior at low temperatures, and so we will consider them separately Figure 13.11 shows the phase diagram for 4He at low temperatures. The normal liquid phase of 4He is called liquid I. Line ab is the vapor pressure line along which (gas + liquid I) equilibrium is maintained, and the (liquid + gas) phase transition is first order. Point a is the critical point of 4He at T= 5.20 K and p — 0.229 MPa. At this point, the (liquid + gas) transition has become continuous. Line be represents the transition between normal liquid (liquid I) and a superfluid phase referred to as liquid II. Along this line the transition... 

Polyatomic Ion Interfered Isotope (Natural Abundance %) Required Resolution... 

According to transition-state theory it is possible to consider reaction velocities in terms of a hypothetical equilibrium between reactants and transition state. It follows that the influence of the isotopic composition of the medium on reaction velocity can be considered to be the same as its influence on the concentration of transition states. The kinetic formulation of the problem can thus be replaced by one couched in equilibrium terms, and the equilibrium theory of the preceding section can be applied with a minimum of modification (Kresge, 1964). The rate constant, or catalytic coefficient, (k) for a catalysed reaction can be written as the product of three factors, viz. the equilibrium constant (K ) for the process forming the transition state from the reactants, the transmission coefficient, and the specific rate of transition state decomposition (kT/h). We recognize that the third factor is independent of the isotopic nature of the reaction and assume that there is no isotope effect on the transmission coefficient. It follows that... 

This is interpreted to indicate that 36Ar is metastable in free space Z/N < r) where it decays to 36S. However, when incorporated into a new condensing galaxy Z/N > r), enhanced gravity stabilizes the metastable nuclide, resulting in the occurrence of nuclide pairs with the same mass number and hence, elements with more than one isotope. Naturally occurring a-emitters are still in a metastable state. The same happens in about half of all cases - in four instances three stable nuclides with the same mass number are formed. The result is the formation of 81 stable nuclides from 50 starting products, in each of the even A series. 

Make a preliminary estimate of the intensity for each element, based on isotopic natural abundances. 

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