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Johnson Matthey Technol. Rev., 2018, 62, (3), 291

doi:10.1595/205651318x15257881075866

The Discoverers of the Isotopes of the Platinum Group of Elements: Update 2018

New isotopes found for Ru, Rh and Pd

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In the 2014 review (1) discovery circumstances for 85Ru and 86Ru were referenced only in the form of a preprint but have now been reported in the open literature (2). For the most recently discovered isotopes the discovery years for both 128Rh and 90Pd are the manuscript dates of the given references whilst for 125Ru, 130Pd and 131Pd the common discovery year corresponds to the original description of these isotopes in a RIKEN Accelerator Progress Report (3). In addition the existence of the isotope 89Rh has been confirmed by Čeliković et al. (4).

No half-lives have been reported for the new isotopes but their very detection indicates that they are all likely to be ‘particle stable’ – that is resistant to proton or neutron decay. The discovery circumstances of the new isotopes are given in Table I where the decay modes are estimated for the particular isotope mass.

Table I
Element Mass number Decay modes Year of discovery Discoverers Reference
Ru 125 β 2014 Shimizu et al. (5)
Rh 128 β 2017 Shimizu et al. (5)
Pd 90 EC + β+ ? 2016 Čeliković et al. (4)
Pd 130 β 2014 Shimizu et al. (5)
Pd 131 β 2014 Shimizu et al. (5)

Notes on Decay Modes

  • EC: Orbital electron capture in which the nucleus captures an extranuclear (orbital) electron which reacts with a proton to form a neutron and a neutrino, so that the mass number of the daughter nuclide remains the same but the atomic number decreases by one

  • β+: Positron decay in which a positron and a neutrino are emitted as a proton in the nucleus decays to a neutron. As with EC the mass number of the daughter nuclide remains the same but the atomic number decreases by one. However this type of decay mode cannot occur unless the decay energy exceeds 1.022 MeV (for example, twice the electron mass in energy units)

  • β: Beta decay in which an electron and an anti-electron neutrino are emitted as a neutron in the nucleus decays to a proton so that the mass number of the daughter nuclide remains the same but the atomic number increases by one

Table II

Total Number of Isotopes and Mass Ranges for Each Platinum Group Element to 2018

Element Number of known isotopes Mass number range
Ru 41 85–125
Rh 40 89–128
Pd 42 90–131
Os 43 161–203
Ir 42 164–205
Pt 43 166–208

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References

  1. 1.
    J. W. Arblaster, Platinum Metals Rev., 2014, 58, (1), 38 LINK https://www.technology.matthey.com/article/58/1/38-39/
  2. 2.
    H. Suzuki, T. Kubo, N. Fukuda, N. Inabe, D. Kameda, H. Takeda, K. Yoshida, K. Kusaka, Y. Yanagisawa, M. Ohtake, H. Sato, Y. Shimizu, H. Baba, M. Kurokawa, K. Tanaka, O. B. Tarasov, D. Bazin, D. J. Morrissey, B. M. Sherrill, K. Ieki, D. Murai, N. Iwasa, A. Chiba, Y. Ohkoda, E. Ideguchi, S. Go, R. Yokoyama, T. Fujii, D. Nishimura, H. Nishibata, S. Momota, M. Lewitowicz, G. DeFrance, I. Celikovic and K. Steiger, Phys. Rev. C, 2017, 96, (3), 034604 LINK https://doi.org/10.1103/PhysRevC.96.034604
  3. 3.
    Y. Shimizu, T. Kubo, N. Fukuda, N. Inabe, D. Kameda, H. Sato, H. Suzuki, H. Takeda, K. Yoshida, H. Baba, F. Browne, P. Doornebal, G. Gey, T. Isobe, A. Jungclaus, Z. Li, G. Lorusso, S. Nishimura, G. Simpson, P.-A. Söderström, T. Sumikama, J. Taprogge, Zs. Vajta, H. Watanabe, J. Wu and Z. Y. Xu, ‘Identification of 18 New Neutron-Rich Isotopes Produced in the EURICA Uranium Beam Campaign’, in “RIKEN Accelerator Progress Report”, Vol. 47, RIKEN Nishina Center for Accelerator-Based Science, Saitama, Japan, 2013, p. 47 LINK http://www.nishina.riken.jp/researcher/APR/APR047/pdf/47.pdf
  4. 4.
    I. Čeliković, M. Lewitowicz, R. Gernhäuser, R. Krücken, S. Nishimura, H. Sakurai, D. S. Ahn, H. Baba, B. Blank, A. Blazhev, P. Boutachkov, F. Browne, G. de France, P. Doornenbal, T. Faestermann, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel, M. Górska, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, Y.-K. Kim, Y. K. Kwon, I. Kojouharov, T. Kubo, N. Kurz, G. Lorusso, D. Lubos, K. Moschner, D. Murai, I. Nishizuka, J. Park, Z. Patel, M. Rajabali, S. Rice, H. Schaffner, Y. Shimizu, L. Sinclair, P.-A. Söderström, K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, H. Watanabe, J. Wu and Z. Xu, Phys. Rev. Lett., 2016, 116, (16), 162501 LINK https://doi.org/10.1103/PhysRevLett.116.162501
  5. 5.
    Y. Shimizu, T. Kubo, N. Fukuda, N. Inabe, D. Kameda, H. Sato, H. Suzuki, H. Takeda, K. Yoshida, G. Lorusso, H. Watanabe, G. S. Simpson, A. Jungclaus, H. Baba, F. Browne, P. Doornenbal, G. Gey, T. Isobe, Z. Li, S. Nishimura, P.-A. Söderström, T. Sumikama, J. Taprogge, Z. Vajta, J. Wu, Z. Xu, A. Odahara, A. Yagi, H. Nishibata, R. Lozeva, C. Moon and H. Jung, J. Phys. Soc. Jpn., 2018, 87, (1), 014203 LINK https://doi.org/10.7566/JPSJ.87.014203
 

The Author


John W. Arblaster is interested in the history of science and the evaluation of the thermodynamic and crystallographic properties of the elements. Now retired, he previously worked as a metallurgical chemist in a number of commercial laboratories and was involved in the analysis of a wide range of ferrous and non-ferrous alloys.

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