Samarium isotope

The primary decay products are neodymium and samarium isotopes. Promethium-146 decays to neodymium and samarium ( " Nd and "" Sm), the lighter isotopes generally to neodymium via positron decay and electron capture, and the heavier isotopes to samarium via beta decay. Exceptions are °Pm and Pm which give rise to Pr ( Pr and respectively) via positron emission. The isotope Pm decays to both Nd and Pr via positron emission, although the majority leads to Nd (Oliveira 2011). 

Samarium is a hard and brittle metal. It is reasonably stable in air but ignites at 150°C. The intermetallic compound SmCOj has markedly ferromagnetic properties and is used in magnets for small electric motors. The radioactive samarium isotope with a half-life of 1.06 10 years is used to determine the age of minerals and... 

The radioactive samarium isotope found in nature, disintegrates very slowly. 

Twenty one isotopes of samarium exist. Natural samarium is a mixture of several isotopes, three of which are unstable with long half-lives. 

When a uranium-235 atom undergoes fission, it splits into two unequal fragments and a number of neutrons and beta particles. The fission process is complicated by the fact that different uranium-235 atoms split up in many different ways. For example, while one atom of 292U is splitting to give isotopes of rubidium (Z = 37) and cesium (Z = 55), another may break up to give isotopes of bromine (Z = 35) and lanthanum (Z = 57), while still another atom yields isotopes of zinc (Z = 30) and samarium (Z = 62) ... 

Sims KWW, DePaolo DJ, Murrell MT, Baldridge WS, Goldstein SJ, Clague DA (1995) Meehanisms of magma generation beneath Hawaii and mid-oeean ridges uranium/ thorium and samarium/ neodymium isotopic evidence. Seienee 267 508-512... 

The first sample we tested was samarium oxide, and we found it to be very radioactive. Now we know today that the radioactive isotope is samarium-147 with a half life of 105,000,000,000 years, and that the radiation is an emission of helium ions (alpha... 

ISOTOPES There are 41 known isotopes of samarium. Seven of these are considered stable. Sm-144 makes up just 3.07% of the natural occurring samarium, Sm-150 makes up 7.38% of natural samarium found on Earth, Sm-152 constitutes 26.75%, and Sm-154 accounts for 22.75%. All the remaining isotopes are radioactive and have very long half-lives therefore, they are considered "stable." All three contribute to the natural occurrence of samarium Sm-147 = 14.99%, Sm-148 = 11.24%, and Sm-149 = 13.82%. 

Samarium is one of the few elements with several stable isotopes that occur naturally on Earth. 

Samarium is a hard, brittle, silver-white metal. When freshly cut, it does not tarnish significantly under normal room temperature conditions. Four of its isotopes are radioactive and emit alpha particles (helium nuclei). They are Sm-l46, Sm-l47, Sm-l48, and Sm-l49. 

Geochronological methods based on REE (plus Hf) have been developed only in the last two decades, because of the high precision required in analysis. Natural samarium has seven isotopes, occurring in the following proportions = 0.0309, 47Sm = 0.1497, = 0.1124, ssm = 0.1383, osm = 0.0744,... 

Sims, K.W.W., DePaolo, D.J., Murrell, M.T., Baldridge, W.S., Goldstein, S.J. and Clague, D.A., 1995. Mechanisms of magma generation beneath Hawaii and mid-ocean ridges Uranium/thorium and samarium/neodymium isotopic evidence. Science, 267 508-512. 

Lin, Z. C., J. M. Ondov, W. R. Kelly, P. J. Paulsen, and R. K. Stevens, Tagging Diesel and Residential Oil Furnace Emissions in Roanoke, Virginia, with Enriched Isotopes of Samarium, J. Air Waste Manage. Assoc., 42, 1057-1062 (1992). 

Samarium has seven naturally occurring isotopes, two of which, 147Sm and 148Sm are radioactive (Table 4.2). The -decay of long-lived 147Sm to 143Nd (t1/2 =1.06 x 1011 years ka =6.54 x 10 12 yr 1) is a widely used chronometer. In contrast, the half-life of... 

Several samarium and neodymium isotopes are isobars (Table 4.2) and cannot be separated by mass spectrometry. Thus, samarium and neodymium must be completely separated by chemical procedures prior to measuring them in a mass spectrometer. The ion-exchange chemistry necessary to separate these elements is now well developed (see Appendix). Isotope measurements can be done either by TIMS or ICPMS (inductively... 

Isotope abundances which are free from all sources of bias are defined as absolute isotope abundances. The absolute isotope composition of elements can be measured by MC-TIMS and MC-ICP-MS via gravimetric synthetic mixtures or standard solutions from highly enriched isotopes, as demonstrated for neodymium,11 erbium13 and samarium,11 13 99 respectively. 

Lide, D, (Editor) CRC Handbook of Chemistry and 84th Edition - A Ready Book of Chemical Reference and Physical Data, CRC Press, LLC.. Boca Raton, FL, 2003. Lngmair, GW. et al. Samarium-146 in the Early Solar System Evidence from Neodymium in the Allende Meteorite, Science, 222, 1015-1017 (1983). Piepgras, D J. and G.J. Wasserburg Isotopic Composition of Neodymium in Waters from the Drake Passage/ Science, 217, 207-214 (1982). 

Table II summarizes the losses we experienced at each step of the target preparation procedure. As the table shows, the most inefficient aspect of our technique is the isotope separation step. Normally, we expect 30% recovery with isotope separation of gadolinium, but this level was obviously not obtained in this particular case. With other rare-earth materials, such as europium and samarium, the expected isotope separation recovery is > 50% and can reach levels as high as 70%. Therefore, allowing for similar chemistry losses, we expect that in those selected cases where isotope separation recoveries are 50%, the amount of initial material required to make a reasonable number of usuable targets can be as low as 100 yg. The amount of intial material required can also be reduced somewhat by paying more attention to increasing the efficiencies of the wet-chemistry yields.

Mendeleev s Periodic Table made no provision for a lanthanide series. No one could predict how many of these elements would exist and it was not until Moseley s work on X-ray spectra that resulted in the concept of atomic number (1913) that it was known that an element with atomic number 61, situated between neodymium and samarium, remained to be discovered. Although several claims were made for its discovery in lanthanide ores, it was realized that no stable isotopes of element 61 existed and, from the late 1930s, nuclear chemistry was applied to its synthesis. 

---