Isotopes of rubidium

Isotopes of rubidium (₃₇Rb)
β−	84Sr
ε	86Kr
Standard atomic weight Ar°(Rb)
	85.4678±0.0003; 85.468±0.001 (abridged);
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Rubidium (₃₇Rb) has 35 known isotopes, from ⁷²Rb to ¹⁰⁶Rb, with naturally occurring rubidium composed of two: stable ⁸⁵Rb (72.2%) and radioactive ⁸⁷Rb (27.8%). The primordial radionuclide ⁸⁷Rb has a half-life of 4.97×10¹⁰ years, beta decaying to stable ⁸⁷Sr. It is, as the element is, widespread on Earth as rubidium readily substitutes for potassium in all minerals. The decay of ⁸⁷Rb has been used extensively in dating rocks; 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 32.82 days, and ⁸⁶Rb with a half-life of 18.645 days. All other radioisotopes have half-lives less than a day, most less than 20 minutes. Of the isomeric states the most stable is ^82mRb at 6.472 hours.

The ground state of ⁸²Rb has a much shorter half-life of 1.2575 minutes. It is used medically in some cardiac positron emission tomography scans to assess myocardial perfusion. It is synthesized through the longer-lived ⁸²Sr, made in a cyclotron, though a generator. It may be administered as the chloride.

List of isotopes

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 and parity^[1] ^{[n 9]}^{[n 5]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy^{[n 5]}			Half-life^[1] ^{[n 4]}^{[n 5]}	Decay mode^[1] ^{[n 6]}	Daughter isotope ^{[n 7]}^{[n 8]}	Spin and parity^[1] ^{[n 9]}^{[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−
⁷⁶Rb	37	39	75.9350730(10)	36.5(6) s	β⁺, α (3.8×10⁻⁷%)	⁷²Se	1−
^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−
^78m2Rb	111.19(22) keV			5.74(3) min	IT (9%)	⁷⁸Rb	4−
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+
^81mRb	86.31(7) keV			30.5(3) min	β⁺ (2.4%)	⁸¹Kr	9/2+
⁸²Rb	37	45	81.9182090(32)	1.2575(2) min	β⁺	⁸²Kr	1+
^82mRb	69.0(15) keV			6.472(6) h	β⁺	⁸²Kr	5−
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)	32.82(7) d	β⁺ (96.1%)	⁸⁴Kr	2−
⁸⁴Rb	37	47	83.9143752(24)	32.82(7) d	β⁻ (3.9%)	⁸⁴Sr	2−
^84mRb	463.59(8) keV			20.26(4) min	IT	⁸⁴Rb	6−
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⁻ (99.9948%)	⁸⁶Sr	2−
⁸⁶Rb	37	49	85.91116744(21)	18.645(8) d	EC (0.0052%)	⁸⁶Kr	2−
^86mRb	556.05(18) keV			1.017(3) min	IT	⁸⁶Rb	6−
⁸⁷Rb^{[n 10]}^{[n 11]}^{[n 12]}	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−
^90mRb	106.90(3) keV			258(4) s	IT (2.6%)	⁹⁰ Rb	3−
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−
⁹²Rb	37	55	91.9197285(66)	4.48(3) s	β⁻, n (0.0107%)	⁹¹Sr	0−
⁹³Rb	37	56	92.9220393(84)	5.84(2) s	β⁻ (98.61%)	⁹³Sr	5/2−
⁹³Rb	37	56	92.9220393(84)	5.84(2) s	β⁻, n (1.39%)	⁹²Sr	5/2−
^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−
⁹⁴Rb	37	57	93.9263948(22)	2.702(5) s	β⁻, n (10.3%)	⁹³Sr	3−
^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−
⁹⁵Rb	37	58	94.929264(22)	377.7(8) ms	β⁻, n (8.7%)	⁹⁴Sr	5/2−
^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−
⁹⁶Rb	37	59	95.9341334(36)	201.5(9) ms	β⁻, n (13.7%)	⁹⁵Sr	2−
^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+
⁹⁷Rb	37	60	96.9371771(21)	169.1(6) ms	β⁻, n (25.5%)	⁹⁶Sr	3/2+
^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+)
⁹⁹Rb	37	62	98.9451192(43)	54(4) ms	β⁻, n (17.3%)	⁹⁸Sr	(3/2+)
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+#
¹⁰¹Rb	37	64	100.954302(22)	31.8(33) ms	β⁻, n (28%)	¹⁰⁰Sr	3/2+#
¹⁰²Rb	37	65	101.960008(89)	37(4) ms	β⁻, n (65%)	¹⁰¹Sr	(4+)
¹⁰²Rb	37	65	101.960008(89)	37(4) ms	β⁻ (35%)	¹⁰²Sr	(4+)
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

^ ^mRb – Excited nuclear isomer.
^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
^ Bold half-life – nearly stable, half-life longer than age of universe.
^ ^a ^b ^c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission
^ Bold italics symbol as daughter – Daughter product is nearly stable.
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ ^a ^b Fission product
^ Primordial radionuclide
^ Used in rubidium–strontium dating
^ Order of ground state and isomer is uncertain.

Rubidium-87

Rubidium-87 is one of two natural isotopes of rubidium, with an abundance of 27.835%, and a half-life of 4.97×10¹⁰ years, with beta decay to strontium-87, a stable isotope.

During fractional crystallization of igneous rock, 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. The age of a mineral, if it has not been subsequently altered, is determined by the parent and daughter abundances, the half-life, and the original content of the daughter, here strontium; the ⁸⁷Sr/⁸⁶Sr ratio helps in its calculation. See rubidium-strontium dating for further detail.

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.

References

^ ^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.
^ "Standard Atomic Weights: Rubidium". CIAAW. 1969.
^ 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.
^ 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.
^ ^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.{{cite journal}}: CS1 maint: article number as page number (link)

[4] Rb – Excited nuclear isomer.

[6] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-7] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[8] Bold half-life – nearly stable, half-life longer than age of universe.

[TNN-9] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[10] Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission

[11] Bold italics symbol as daughter – Daughter product is nearly stable.

[12] Bold symbol as daughter – Daughter product is stable.

[13] ( ) spin value – Indicates spin with weak assignment arguments.

[FP-14] Fission product

[15] Primordial radionuclide

[16] Used in rubidium–strontium dating

[order-17] Order of ground state and isomer is uncertain.

[NUBASE2020-1] 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.

[CIAAWrubidium-2] "Standard Atomic Weights: Rubidium". CIAAW. 1969.

[CIAAW2021-3] 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.

[AME2020_II-5] 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.

[Sumikama(Rb)-18] 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.{{cite journal}}: CS1 maint: article number as page number (link)

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Isotopes of rubidium

Isotopes of rubidium

Isotopes of rubidium

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Root Wikipedia Article

Isotopes of rubidium

List of isotopes

Rubidium-87

See also

References

EC:	Electron capture
IT:	Isomeric transition
n:	Neutron emission
p:	Proton emission