Isotopes of rubidium (original) (raw)

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Isotopes of rubidium (37Rb)

Main isotopes[1] Decay abun­dance half-life (_t_1/2) mode pro­duct 82Rb synth 1.2575 m β+ 82Kr 83Rb synth 86.2 d ε 83Kr γ – 84Rb synth 32.9 d ε 84Kr β+ 84Kr γ – β− 84Sr 85Rb 72.2% stable 86Rb synth 18.7 d β− 86Sr γ – 87Rb 27.8% 4.923×1010 y β− 87Sr
Standard atomic weight _A_r°(Rb)
85.4678±0.0003[2]85.468±0.001 (abridged)[3]
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Rubidium (37Rb) has 36 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb (72.2%) and the radioactive 87Rb (27.8%).

87Rb has a half-life of 4.92×1010 years. It readily substitutes for potassium in minerals, and is therefore fairly widespread. 87Rb has been used extensively in dating rocks; 87Rb decays to stable strontium-87 by emission of a beta particle (an electron ejected from the nucleus). During fractional crystallization, Sr tends to become concentrated in plagioclase, leaving Rb in the liquid phase. Hence, the Rb/Sr ratio in residual magma may increase over time, resulting in rocks with increasing Rb/Sr ratios with increasing differentiation. The highest ratios (10 or higher) occur in pegmatites. If the initial amount of Sr is known or can be extrapolated, the age can be determined by measurement of the Rb and Sr concentrations and the 87Sr/86Sr ratio. The dates indicate the true age of the minerals only if the rocks have not been subsequently altered. See rubidium–strontium dating for a more detailed discussion.

Other than 87Rb, the longest-lived radioisotopes are 83Rb with a half-life of 86.2 days, 84Rb with a half-life of 33.1 days, and 86Rb with a half-life of 18.642 days. All other radioisotopes have half-lives less than a day.

82Rb is used in some cardiac positron emission tomography scans to assess myocardial perfusion. It has a half-life of 1.273 minutes. It does not exist naturally, but can be made from the decay of 82Sr.

| Nuclide[n 1] | Z | N | Isotopic mass (Da)[4][n 2][n 3] | Half-life[1][n 4][n 5] | Decay mode[1][n 6] | Daughter isotope[n 7][n 8] | Spin andparity[1][n 9][n 5] | Natural abundance (mole fraction) | | | ----------------------------------------------------------------------------------------------- | --------------------------------------------------- | ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------- | | | Excitation energy[n 5] | Normal proportion[1] | Range of variation | | | | | | | | | 72Rb | 37 | 35 | 71.95885(54)# | 103(22) ns | p | 71Kr | 1+# | | | | 73Rb | 37 | 36 | 72.950605(44) | <81 ns | p | 72Kr | 3/2−# | | | | 74Rb | 37 | 37 | 73.9442659(32) | 64.78(3) ms | β+ | 74Kr | 0+ | | | | 75Rb | 37 | 38 | 74.9385732(13) | 19.0(12) s | β+ | 75Kr | 3/2− | | | | 76Rb | 37 | 39 | 75.9350730(10) | 36.5(6) s | β+ | 76Kr | 1− | | | | β+, α (3.8×10−7%) | 72Se | | | | | | | | | | 76mRb | 316.93(8) keV | 3.050(7) μs | IT | 76Rb | (4+) | | | | | | 77Rb | 37 | 40 | 76.9304016(14) | 3.78(4) min | β+ | 77Kr | 3/2− | | | | 78Rb | 37 | 41 | 77.9281419(35) | 17.66(3) min | β+ | _**78Kr**_ | 0+ | | | | 78m1Rb | 46.84(14) keV | 910(40) ns | IT | 78Rb | (1−) | | | | | | 78m2Rb | 111.19(22) keV | 5.74(3) min | β+ (91%) | _**78Kr**_ | 4− | | | | | | IT (9%) | 78Rb | | | | | | | | | | 79Rb | 37 | 42 | 78.9239901(21) | 22.9(5) min | β+ | 79Kr | 5/2+ | | | | 80Rb | 37 | 43 | 79.9225164(20) | 33.4(7) s | β+ | **80Kr** | 1+ | | | | 80mRb | 493.9(5) keV | 1.63(4) μs | IT | 80Rb | (6+) | | | | | | 81Rb | 37 | 44 | 80.9189939(53) | 4.572(4) h | β+ | 81Kr | 3/2− | | | | 81mRb | 86.31(7) keV | 30.5(3) min | IT (97.6%) | 81Rb | 9/2+ | | | | | | β+ (2.4%) | 81Kr | | | | | | | | | | 82Rb | 37 | 45 | 81.9182090(32) | 1.2575(2) min | β+ | **82Kr** | 1+ | | | | 82mRb | 69.0(15) keV | 6.472(6) h | β+ (>99.67%) | 82Kr | 5− | | | | | | IT (<0.33%) | 82Rb | | | | | | | | | | 83Rb | 37 | 46 | 82.9151142(25) | 86.2(1) d | EC | **83Kr** | 5/2− | | | | 83mRb | 42.0780(20) keV | 7.8(7) ms | IT | 83Rb | 9/2+ | | | | | | 84Rb | 37 | 47 | 83.9143752(24) | 32.8(07) d | β+ (96.1%) | **84Kr** | 2− | | | | β− (3.9%) | **84Sr** | | | | | | | | | | 84mRb | 463.59(8) keV | 20.26(4) min | IT | 84Rb | 6− | | | | | | β+ (<0.0012%) | **84Kr** | | | | | | | | | | 85Rb[n 10] | 37 | 48 | 84.9117897360(54) | **Stable** | 5/2− | 0.7217(2) | | | | | 85mRb | 514.0065(22) keV | 1.015(1) μs | IT | **85Rb** | 9/2+ | | | | | | 86Rb | 37 | 49 | 85.91116744(21) | 18.645(8) d | β− (99.99%) | **86Sr** | 2− | | | | EC (.0052%) | **86Kr** | | | | | | | | | | 86mRb | 556.05(18) keV | 1.017(3) min | IT (>99.7%) | 86Rb | 6− | | | | | | β− (<0.3%) | **86Sr** | | | | | | | | | | 87Rb[n 11][n 12][n 10] | 37 | 50 | 86.909180529(6) | **4.97(3)×1010 y** | β− | **87Sr** | 3/2− | 0.2783(2) | | | 88Rb | 37 | 51 | 87.91131559(17) | 17.78(3) min | β− | **88Sr** | 2− | | | | 88mRb | 1373.8(3) keV | 123(13) ns | IT | 88Rb | (7+) | | | | | | 89Rb | 37 | 52 | 88.9122781(58) | 15.32(10) min | β− | 89Sr | 3/2− | | | | 90Rb | 37 | 53 | 89.9147976(69) | 158(5) s | β− | 90Sr | 0− | | | | 90mRb | 106.90(3) keV | 258(4) s | β− (97.4%) | 90Sr | 3− | | | | | | IT (2.6%) | 90 Rb | | | | | | | | | | 91Rb | 37 | 54 | 90.9165373(84) | 58.2(3) s | β− | 91Sr | 3/2− | | | | 92Rb | 37 | 55 | 91.9197285(66) | 4.48(3) s | β− (99.99%) | 92Sr | 0− | | | | β−, n (0.0107%) | 91Sr | | | | | | | | | | 93Rb | 37 | 56 | 92.9220393(84) | 5.84(2) s | β− (98.61%) | 93Sr | 5/2− | | | | β−, n (1.39%) | 92Sr | | | | | | | | | | 93mRb | 4423.1(15) keV | 111(11) ns | IT | 93Rb | (27/2−) | | | | | | 94Rb | 37 | 57 | 93.9263948(22) | 2.702(5) s | β− (89.7%) | 94Sr | 3− | | | | β−, n (10.3%) | 93Sr | | | | | | | | | | 94m1Rb | 104.2(2) keV | 130(15) ns | IT | 94Rb | (0−) | | | | | | 94m2Rb | 2074.9(14) keV | 107(16) ns | IT | 94Rb | (10−) | | | | | | 95Rb | 37 | 58 | 94.929264(22) | 377.7(8) ms | β− (91.3%) | 95Sr | 5/2− | | | | β−, n (8.7%) | 94Sr | | | | | | | | | | 95mRb | 835.0(6) keV | <500 ns | IT | 95Rb | 9/2+# | | | | | | 96Rb | 37 | 59 | 95.9341334(36) | 201.5(9) ms | β− (86.3%) | 96Sr | 2− | | | | β−, n (13.7%) | 95Sr | | | | | | | | | | 96m1Rb[n 13] | 0(200)# keV | 200# ms[>1 ms] | | | 1(+#) | | | | | | 96m2Rb | 1134.6(11) keV | 1.80(4) μs | IT | 96Rb | (10−) | | | | | | 97Rb | 37 | 60 | 96.9371771(21) | 169.1(6) ms | β− (74.5%) | 97Sr | 3/2+ | | | | β−, n (25.5%) | 96Sr | | | | | | | | | | 97mRb | 76.6(2) keV | 5.7(6) μs | IT | 97Rb | (1/2,3/2)− | | | | | | 98Rb | 37 | 61 | 97.941632(17) | 115(6) ms | β−(85.65%) | 98Sr | (0−) | | | | β−, n (14.3%) | 97Sr | | | | | | | | | | β−, 2n (0.054%) | 96Sr | | | | | | | | | | 98m1Rb | 73(26) keV | 96(3) ms | β− | 98Sr | (3+) | | | | | | 98m2Rb | 178.5(4) keV | 358(7) ns | IT | 98Rb | (2−) | | | | | | 99Rb | 37 | 62 | 98.9451192(43) | 54(4) ms | β− (82.7%) | 99Sr | (3/2+) | | | | β−, n (17.3%) | 98Sr | | | | | | | | | | 100Rb | 37 | 63 | 99.950332(14) | 51.3(16) ms | β− (94.3%) | 100Sr | 4−# | | | | β−, n (5.6%) | 99Sr | | | | | | | | | | β−, 2n (0.15%) | 98Sr | | | | | | | | | | 101Rb | 37 | 64 | 100.954302(22) | 31.8(33) ms | β− (72%) | 101Sr | 3/2+# | | | | β−, n (28%) | 100Sr | | | | | | | | | | 102Rb | 37 | 65 | 101.960008(89) | 37(4) ms | β−, n (65%) | 101Sr | (4+) | | | | β− (35%) | 102Sr | | | | | | | | | | 103Rb | 37 | 66 | 102.96440(43)# | 26(11) ms | β− | 103Sr | 3/2+# | | | | 104Rb | 37 | 67 | 103.97053(54)# | 35# ms[>550 ns] | | | | | | | 105Rb[5] | 37 | 68 | | | | | | | | | 106Rb[5] | 37 | 69 | | | | | | | | | This table header & footer: view | | | | | | | | | |

  1. ^ mRb – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1_σ_) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ Bold half-life – nearly stable, half-life longer than age of universe.
  5. ^ a b c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. ^ Modes of decay:
  7. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
  8. ^ Bold symbol as daughter – Daughter product is stable.
  9. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  10. ^ a b Fission product
  11. ^ Primordial radionuclide
  12. ^ Used in rubidium–strontium dating
  13. ^ Order of ground state and isomer is uncertain.

Rubidium-87 was the first and the most popular atom for making Bose–Einstein condensates in dilute atomic gases. Even though rubidium-85 is more abundant, rubidium-87 has a positive scattering length, which means it is mutually repulsive, at low temperatures. This prevents a collapse of all but the smallest condensates. It is also easy to evaporatively cool, with a consistent strong mutual scattering. There is also a strong supply of cheap uncoated diode lasers typically used in CD writers, which can operate at the correct wavelength.

Rubidium-87 has an atomic mass of 86.9091835 u, and a binding energy of 757,853 keV. Its atomic percent abundance is 27.835%, and has a half-life of 4.92×1010 years.

  1. ^ a b c d e Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ^ "Standard Atomic Weights: Rubidium". CIAAW. 1969.
  3. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  5. ^ a b Sumikama, T.; et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of 110Zr". Physical Review C. 103 (1): 014614. Bibcode:2021PhRvC.103a4614S. doi:10.1103/PhysRevC.103.014614. hdl:10261/260248. S2CID 234019083.