Alpha nuclide

An alpha nuclide is a nuclide that consists of an integer number of alpha particles. Alpha nuclides have equal, even numbers of protons and neutrons; they are important in stellar nucleosynthesis since the energetic environment within stars is amenable to fusion of alpha particles into heavier nuclei.^[1]^[2] Stable alpha nuclides, and stable decay products of radioactive alpha nuclides, are some of the most common metals in the universe.

Alpha nuclide is also shorthand for alpha radionuclide, referring to those radioactive isotopes that undergo alpha decay and thereby emit alpha particles.^[3]

List of alpha nuclides

The entries for ³⁶Ar and ⁴⁰Ca are theoretical: they would release energy on decay, but the process has never been observed, and the half-lives are probably extremely long. Likewise, the chains for masses 64, 84, 92, and 96 theoretically can continue one more step by double electron capture (to ⁶⁴Ni, ⁸⁴Kr, ⁹²Zr, and ⁹⁶Mo respectively), but this has never been observed.

Alpha number	nuclide	Stable/radioactive	decay mode	half-life^[4]	product(s) of decay (bold is stable)	alpha decay energy^[5]
1	⁴ ₂He	Stable
2	⁸ ₄Be	Radioactive	α	8.19(37)×10⁻¹⁷ s	⁴ ₂He	+0.09184MeV
3	¹² ₆C	Stable				-7.36659MeV
4	¹⁶ ₈O	Stable				-7.16192MeV
5	²⁰ ₁₀Ne	Stable				-4.72985MeV
6	²⁴ ₁₂Mg	Stable				-9.31656MeV
7	²⁸ ₁₄Si	Stable				-9.98414MeV
8	³² ₁₆S	Stable				-6.94766MeV
9	³⁶ ₁₈Ar	Observationally Stable	(ECEC)	never seen	(³⁶ ₁₆S )	-6.64092MeV
10	⁴⁰ ₂₀Ca	Observationally Stable	(ECEC)	never seen	(⁴⁰ ₁₈Ar )	-7.03978MeV
11	⁴⁴ ₂₂Ti	Radioactive	EC	60.0(11) y	⁴⁴ ₂₁Sc → ⁴⁴ ₂₀Ca	-5.1271MeV
12	⁴⁸ ₂₄Cr	Radioactive	β⁺	21.56(3) h	⁴⁸ ₂₃V → ⁴⁸ ₂₂Ti	-7.698MeV
13	⁵² ₂₆Fe	Radioactive	β⁺	8.275(8) h	^52m ₂₅Mn → ⁵² ₂₄Cr	-7.936MeV
14	⁵⁶ ₂₈Ni	Radioactive	β⁺	6.075(10) d	⁵⁶ ₂₇Co → ⁵⁶ ₂₆Fe	-8.0005MeV
15	⁶⁰ ₃₀Zn	Radioactive	β⁺	2.38(5) min	⁶⁰ ₂₉Cu → ⁶⁰ ₂₈Ni	-2.6917MeV
16	⁶⁴ ₃₂Ge	Radioactive	β⁺	63.7(25) s	⁶⁴ ₃₁Ga → ⁶⁴ ₃₀Zn	-2.566MeV
17	⁶⁸ ₃₄Se	Radioactive	β⁺	35.5(7) s	⁶⁸ ₃₃As → ... → ⁶⁸ ₃₀Zn	-2.299MeV
18	⁷² ₃₆Kr	Radioactive	β⁺	17.16(18) s	⁷² ₃₅Br → ... → ⁷² ₃₂Ge	-2.176MeV
19	⁷⁶ ₃₈Sr	Radioactive	β⁺	7.89(7) s	⁷⁶ ₃₇Rb → ... → ⁷⁶ ₃₄Se	-2.73MeV
20	⁸⁰ ₄₀Zr	Radioactive	β⁺	4.6(6) s	⁸⁰ ₃₉Y → ... → ⁸⁰ ₃₆Kr	-3.70MeV
21	⁸⁴ ₄₂Mo	Radioactive	β⁺	3.8(9) ms	⁸⁴ ₄₁Nb → ... → ⁸⁴ ₃₈Sr	-2.71MeV
22	⁸⁸ ₄₄Ru	Radioactive	β⁺	1.3(3) s	⁸⁸ ₄₃Tc → ... → ⁸⁸ ₃₈Sr	-2.27MeV
23	⁹² ₄₆Pd	Radioactive	β⁺	1.1(3) s	⁹² ₄₅Rh → ... → ⁹² ₄₂Mo	-2.28MeV
24	⁹⁶ ₄₈Cd	Radioactive	β⁺	~1 s	⁹⁶ ₄₇Ag → ... → ⁹⁶ ₄₄Ru	-3.03MeV
25	¹⁰⁰ ₅₀Sn	Radioactive	β⁺	1.1(4) s	¹⁰⁰ ₄₉In → ... → ¹⁰⁰ ₄₄Ru	-3.47MeV
26	¹⁰⁴ ₅₂Te	Radioactive	α	<18 ns	¹⁰⁰ ₅₀Sn → ... → ¹⁰⁰ ₄₄Ru	+5.10MeV
27	¹⁰⁸ ₅₄Xe	Radioactive	α	58⁺¹⁰⁶ ₋₂₃ μs	¹⁰⁴ ₅₂Te → ¹⁰⁰ ₅₀Sn → ... → ¹⁰⁰ ₄₄Ru	+4.57MeV

As of 2024^[update], the heaviest known alpha nuclide is xenon-108.^[6]

References

^ Appenzeller; Harwit; Kippenhahn; Strittmatter; Trimble, eds. (1998). Astrophysics Library (3rd ed.). New York: Springer.
^ Carroll, Bradley W. & Ostlie, Dale A. (2007). An Introduction to Modern Stellar Astrophysics. Addison Wesley, San Francisco. ISBN 978-0-8053-0348-3.
^ John Avison (November 2014). The World of Physics. Nelson Thornes. pp. 397–. ISBN 978-0-17-438733-6.
^ Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
^ 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.
^ Auranen, K.; et al. (2018). "Superallowed α decay to doubly magic ¹⁰⁰Sn" (PDF). Physical Review Letters. 121 (18): 182501. doi:10.1103/PhysRevLett.121.182501. PMID 30444390.

[Appenzeller-1] Appenzeller; Harwit; Kippenhahn; Strittmatter; Trimble, eds. (1998). Astrophysics Library (3rd ed.). New York: Springer.

[Ostlie-2] Carroll, Bradley W. & Ostlie, Dale A. (2007). An Introduction to Modern Stellar Astrophysics. Addison Wesley, San Francisco. ISBN 978-0-8053-0348-3.

[3] John Avison (November 2014). The World of Physics. Nelson Thornes. pp. 397–. ISBN 978-0-17-438733-6.

[NUBASE2016-4] Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.

[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.

[Xe108-6] Auranen, K.; et al. (2018). "Superallowed α decay to doubly magic ¹⁰⁰Sn" (PDF). Physical Review Letters. 121 (18): 182501. doi:10.1103/PhysRevLett.121.182501. PMID 30444390.

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