Silver isotope

Schonbachler, M., Carlson, R. W., Horan, M. E, Mock, T. D. and Hauri, E. H. (2008) Silver isotope variations in chondrites Volatile depletion and the initial 107Pd abundance of the solar system. Geochimica et Cosmochimica Acta, 72, 5330-5341. 

Irradiation with charged particles accelerated in a cyclotron, while eliminating the problem of long-lived silver isotopes caused by the different nuclear reactions involved, is not feasible for any large-scale study because of the cost involved. Unlike a nuclear reactor, where numerous different samples can be irradiated simultaneously, only a single sample can be irradiated using a cyclotron beam. 

Neutron Howitzer Irradiation. Whole-coin irradiation, however, has the advantage that the internal portions of the coin are irradiated and activated, thus permitting nondestructive analysis of the entire coin. One method we have devised is based on such irradiation but in a neutron beam that is about 100,000,000th as intense as that in a reactor. Only the silver in the coin is activated sufficiently for detection. None of the 255-day half-life isotope is detected, and the analysis is based on silver isotopes with half-lives of 24 sec (110Ag) and 2.4 min (108Ag). This silver activity dissipates in 10-15 min, and the coin is unharmed. We have analyzed over 4000 coins by this method which is described in Refs. 2, 3, 4. 

TABLE 1. Properties of gold and silver isotopes (compared to the proton)... 

E. Radioanalytical and Environmental Studies with Silver Isotopes. 498... 

F. Radioanalytical and Biomedical Studies with Silver Isotopes. 500... 

Brian L. Silver, Isotope Department, The Weizmann Institute of Science, Rehovoth, Israel... 

Despite its low volatility, silver trifluoromethanesulfonate (38) gave an El mass spectrum with intense [M + Ag] + ions, leading to the suggestion that 38 vaporized as a dimer34. FD mass spectra of both 38 and silver methanesulfonate (39) showed the presence of cluster ions [nM + Ag]+, with n = 1-6 for 38 and n = 1-7 for 3935a. Each cluster ion yielded multiple peaks with relative intensities determined by the presence of the silver isotopes. A mixture of the two compounds showed a FD mass spectrum comprising additional clusters with mixed anions. Thus, the resulting spectrum had relatively intense... 

J(P-Ag) = 9.1 Hz. Both silver isotopes (see Isotopes Isotope Labeling couple nearly equivalently, and hence only a doublet appears. The C H spectra were the first to demonstrate spin-spin coupling. The neutral... 

The deposition of fission products on primary circuit surfaces and, in particular, on the reformer tube walls causes difficulties during maintenance and catalyst refilling procedures, if the activity is intolerably high. Cesium and silver isotopes released during reactor operation are of major concern. Particularly silver diffuses easily out of the fuel elements at operating temperature conditions into the coolant and migrates easily into metal surfaces and is difficult to remove in decontamination operations [32]. 

In a gas turbine version of the HTTR, half of the radiation dose is estimated to originate from the silver isotope Ag-llOm. Countermeasures could be either a fuel temperature reduction which would require a change of the core design, or the use of advanced fuel with the most efficient barrier against fission product release, the SiC coating layer, to be substituted by a ZrC layer. The higher retentivity of ZrC against Ag release, however, needs further confirmation [40]. 

Some of these points will have conflicting requirements. For instance the natural abundances of the two silver isotopes are very similar. It is, therefore, not practicable to adhere to a matching procedure which normally aims for isotope amount ratio measurements close to unity after spiking. To help clarify the different aspects, each is discussed below. 

Woodland, S.J., Rebkamper, M., Halbday, A.N., Lee, D.-C., Hattendorf, B., and Giinfher, D. (2005) Accurate measmement of silver isotopic compositions in geological materials including low Pd/Ag meteorites. Geochim. Cosmochim. Acta, 69, 2153-2163. 

Luo, Y., Dabek-Zlotorzynska, E., Celo, V., Muir, D.C.G., and Yang, L. (2010) Accurate and precise determination of silver isotope fractionation in environmental samples by multicollector-ICPMS. Anal. Chem.,... 

Silver. Both silver isotopes also have spin i and small magnetic moments. The Knight shift of Ag was measured by von Meerwall et al. (1975) in LaAg (CsCI structure) between 1.5 and 300 K. The shift is approximately one-half that in silver metal itself. 

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