Physics:Isotopes of rubidium

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Short description: Nuclides with atomic number of 37 but with different mass numbers
Main isotopes of Chemistry:rubidium (37Rb)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
83Rb syn 86.2 d ε 83Kr
γ –
84Rb syn 32.9 d ε 84Kr
β+ 84Kr
γ –
β− 84Sr
85Rb 72.17% stable
86Rb syn 18.7 d β− 86Sr
γ –
87Rb 27.83% 4.9×1010 y β− 87Sr
Standard atomic weight Ar, standard(Rb)
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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%). Normal mixes[clarification needed] of rubidium are radioactive enough to fog photographic film in approximately 30 to 60 days.

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.

List of isotopes

Nuclide
[n 1] 		Z N Isotopic mass (u)
[n 2][n 3] 		Half-life
[n 4][n 5] 		Decay
mode
[n 6] 		Daughter
isotope
[n 7][n 8] 		Spin and
parity
[n 9][n 5] 		Physics:Natural abundance (mole fraction)
Excitation energy[n 5] Normal proportion Range of variation
71Rb 37 34 70.96532(54)# p 70Kr 5/2−#
72Rb 37 35 71.95908(54)# <1.5 μs p 71Kr 3+#
72mRb 100(100)# keV 1# μs p 71Kr 1−#
73Rb 37 36 72.95056(16)# <30 ns p 72Kr 3/2−#
74Rb 37 37 73.944265(4) 64.76(3) ms β+ 74Kr (0+)
75Rb 37 38 74.938570(8) 19.0(12) s β+ 75Kr (3/2−)
76Rb 37 39 75.9350722(20) 36.5(6) s β+ 76Kr 1(−)
β+, α (3.8×10−7%) 72Se
76mRb 316.93(8) keV 3.050(7) μs (4+)
77Rb 37 40 76.930408(8) 3.77(4) min β+ 77Kr 3/2−
78Rb 37 41 77.928141(8) 17.66(8) min β+ 78Kr 0(+)
78mRb 111.20(10) keV 5.74(5) min β+ (90%) 78Kr 4(−)
IT (10%) 78Rb
79Rb 37 42 78.923989(6) 22.9(5) min β+ 79Kr 5/2+
80Rb 37 43 79.922519(7) 33.4(7) s β+ 80Kr 1+
80mRb 494.4(5) keV 1.6(2) μs 6+
81Rb 37 44 80.918996(6) 4.570(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 81.9182086(30) 1.273(2) min β+ 82Kr 1+
82mRb 69.0(15) keV 6.472(5) h β+ (99.67%) 82Kr 5−
IT (.33%) 82Rb
83Rb 37 46 82.915110(6) 86.2(1) d EC 83Kr 5/2−
83mRb 42.11(4) keV 7.8(7) ms IT 83Rb 9/2+
84Rb 37 47 83.914385(3) 33.1(1) d β+ (96.2%) 84Kr 2−
β− (3.8%) 84Sr
84mRb 463.62(9) keV 20.26(4) min IT (>99.9%) 84Rb 6−
β+ (<.1%) 84Kr
85Rb[n 10] 37 48 84.911789738(12) Stable 5/2− 0.7217(2)
86Rb 37 49 85.91116742(21) 18.642(18) d β− (99.9948%) 86Sr 2−
EC (.0052%) 86Kr
86mRb 556.05(18) keV 1.017(3) min IT 86Rb 6−
87Rb[n 11][n 12][n 10] 37 50 86.909180527(13) 4.923(22)×1010 y β− 87Sr 3/2− 0.2783(2)
88Rb 37 51 87.91131559(17) 17.773(11) min β− 88Sr 2−
89Rb 37 52 88.912278(6) 15.15(12) min β− 89Sr 3/2−
90Rb 37 53 89.914802(7) 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 90.916537(9) 58.4(4) s β− 91Sr 3/2(−)
92Rb 37 55 91.919729(7) 4.492(20) s β− (99.98%) 92Sr 0−
β−, n (.0107%) 91Sr
93Rb 37 56 92.922042(8) 5.84(2) s β− (98.65%) 93Sr 5/2−
β−, n (1.35%) 92Sr
93mRb 253.38(3) keV 57(15) μs (3/2−,5/2−)
94Rb 37 57 93.926405(9) 2.702(5) s β− (89.99%) 94Sr 3(−)
β−, n (10.01%) 93Sr
95Rb 37 58 94.929303(23) 377.5(8) ms β− (91.27%) 95Sr 5/2−
β−, n (8.73%) 94Sr
96Rb 37 59 95.93427(3) 202.8(33) ms β− (86.6%) 96Sr 2+
β−, n (13.4%) 95Sr
96mRb 0(200)# keV 200# ms [>1 ms] β− 96Sr 1(−#)
IT 96Rb
β−, n 95Sr
97Rb 37 60 96.93735(3) 169.9(7) ms β− (74.3%) 97Sr 3/2+
β−, n (25.7%) 96Sr
98Rb 37 61 97.94179(5) 114(5) ms β−(86.14%) 98Sr (0,1)(−#)
β−, n (13.8%) 97Sr
β−, 2n (.051%) 96Sr
98mRb 290(130) keV 96(3) ms β− 97Sr (3,4)(+#)
99Rb 37 62 98.94538(13) 50.3(7) ms β− (84.1%) 99Sr (5/2+)
β−, n (15.9%) 98Sr
100Rb 37 63 99.94987(32)# 51(8) ms β− (94.25%) 100Sr (3+)
β−, n (5.6%) 99Sr
β−, 2n (.15%) 98Sr
101Rb 37 64 100.95320(18) 32(5) ms β− (69%) 101Sr (3/2+)#
β−, n (31%) 100Sr
102Rb 37 65 101.95887(54)# 37(5) ms β− (82%) 102Sr
β−, n (18%) 101Sr
103Rb[2] 37 66 26 ms β− 103Sr
104Rb[3] 37 67 35# ms (>550 ns) β−? 104Sr
105Rb[4] 37 68
106Rb[4] 37 69
  1. ↑ mRb – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) 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. ↑ 5.0 5.1 5.2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. ↑ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  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. ↑ 10.0 10.1 Fission product
  11. ↑ Primordial radionuclide
  12. ↑ Used in rubidium–strontium dating

Rubidium-87

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.

References

  1. ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305. 
  2. ↑ Ohnishi, Tetsuya et al. (2010). "Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon". J. Phys. Soc. Jpn. (Physical Society of Japan) 79 (7): 073201. doi:10.1143/JPSJ.79.073201. Bibcode: 2010JPSJ...79g3201T. 
  3. ↑ Shimizu, Yohei et al. (2018). "Observation of New Neutron-rich Isotopes among Fission Fragments from In-flight Fission of 345 MeV/Nucleon 238U: Search for New Isotopes Conducted Concurrently with Decay Measurement Campaigns". Journal of the Physical Society of Japan 87 (1): 014203. doi:10.7566/JPSJ.87.014203. Bibcode: 2018JPSJ...87a4203S. 
  4. ↑ 4.0 4.1 Sumikama, T. (2021). "Observation of new neutron-rich isotopes in the vicinity of 110Zr". Physical Review C 103 (1): 014614. doi:10.1103/PhysRevC.103.014614. Bibcode: 2021PhRvC.103a4614S. https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.014614. 



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