Isotopes of silicon

Isotopes of silicon (₁₄Si)
Standard atomic weight 28.085±0.001 (abridged)
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Silicon (₁₄Si) has 23 known isotopes, with mass numbers ranging from 22 to 44. ²⁸Si (the most abundant isotope, at 92.23%), ²⁹Si (4.67%), and ³⁰Si (3.1%) are stable. The longest-lived radioisotope is ³²Si, which is produced by cosmic ray spallation of argon. Its half-life has been determined to be approximately 150 years (with decay energy 0.21 MeV), and it decays by beta emission to ³²P (which has a 14.27-day half-life)^[1] and then to ³²S. After ³²Si, ³¹Si has the second longest half-life at 157.3 minutes. All others have half-lives under 7 seconds.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass [n 2]^{[n 3]}	Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy			Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Normal proportion^[1]	Range of variation
²²Si	14	8	22.03611(54)#	28.7(11) ms	β⁺, p (62%)	²¹Mg	0+
					β⁺ (37%)	²²Al
					β⁺, 2p (0.7%)	²⁰Na
²³Si	14	9	23.02571(54)#	42.3(4) ms	β⁺, p (88%)	²²Mg	3/2+#
					β⁺ (8%)	²³Al
					β⁺, 2p (3.6%)	²¹Na
²⁴Si	14	10	24.011535(21)	143.2 (21) ms	β⁺ (65.5%)	²⁴Al	0+
²⁴Si	14	10	24.011535(21)	143.2 (21) ms	β⁺, p (34.5%)	²³Mg	0+
²⁵Si	14	11	25.004109(11)	220.6(10) ms	β⁺ (65%)	²⁵Al	5/2+
²⁵Si	14	11	25.004109(11)	220.6(10) ms	β⁺, p (35%)	²⁴Mg	5/2+
²⁶Si	14	12	25.99233382(12)	2.2453(7) s	β⁺	²⁶Al	0+
²⁷Si	14	13	26.98670469(12)	4.117(14) s	β⁺	²⁷Al	5/2+
²⁸Si	14	14	27.97692653442(55)	Stable			0+	0.92223(19)	0.92205–0.92241
²⁹Si	14	15	28.97649466434(60)	Stable			1/2+	0.04685(8)	0.04678–0.04692
³⁰Si	14	16	29.973770137(23)	Stable			0+	0.03092(11)	0.03082–0.03102
³¹Si	14	17	30.975363196(46)	157.16(20) min	β⁻	³¹P	3/2+
³²Si	14	18	31.97415154(32)	157(7) y	β⁻	³²P	0+	trace	cosmogenic
³³Si	14	19	32.97797696(75)	6.18(18) s	β⁻	³³P	3/2+
³⁴Si	14	20	33.97853805(86)	2.77(20) s	β⁻	³⁴P	0+
^34mSi	4256.1(4) keV			<210 ns	IT	³⁴Si	(3−)
³⁵Si	14	21	34.984550(38)	780(120) ms	β⁻	³⁵P	7/2−#
³⁵Si	14	21	34.984550(38)	780(120) ms	β⁻, n?	³⁴P	7/2−#
³⁶Si	14	22	35.986649(77)	503(2) ms	β⁻ (88%)	³⁶P	0+
³⁶Si	14	22	35.986649(77)	503(2) ms	β⁻, n (12%)	³⁵P	0+
³⁷Si	14	23	36.99295(12)	141.0(35) ms	β⁻ (83%)	³⁷P	(5/2−)
					β⁻, n (17%)	³⁶P
					β⁻, 2n?	³⁵P
³⁸Si	14	24	37.99552(11)	63(8) ms	β⁻ (75%)	³⁸P	0+
³⁸Si	14	24	37.99552(11)	63(8) ms	β⁻, n (25%)	³⁷P	0+
³⁹Si	14	25	39.00249(15)	41.2(41) ms	β⁻ (67%)	³⁹P	(5/2−)
					β⁻, n (33%)	³⁸P
					β⁻, 2n?	³⁷P
⁴⁰Si	14	26	40.00608(13)	31.2(26) ms	β⁻ (62%)	⁴⁰P	0+
					β⁻, n (38%)	³⁹P
					β⁻, 2n?	³⁸P
⁴¹Si	14	27	41.01417(32)#	20.0(25) ms	β⁻, n (>55%)	⁴⁰P	7/2−#
					β⁻ (<45%)	⁴¹P
					β⁻, 2n?	³⁹P
⁴²Si	14	28	42.01808(32)#	15.5(4 (stat), 16 (sys)) ms^[5]	β⁻ (51%)	⁴²P	0+
					β⁻, n (48%)	⁴¹P
					β⁻, 2n (1%)	⁴⁰P
⁴³Si	14	29	43.02612(43)#	13(4 (stat), 2 (sys)) ms^[5]	β⁻, n (52%)	⁴²P	3/2−#
					β⁻ (27%)	⁴³P
					β⁻, 2n (21%)	⁴¹P
⁴⁴Si	14	30	44.03147(54)#	4# ms [>360 ns]	β⁻?	⁴⁴P	0+
					β⁻, n?	⁴³P
					β⁻, 2n?	⁴²P
This table header & footer: view

^ ^mSi – 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).
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Modes of decay:

IT: Isomeric transition

n: Neutron emission

p: Proton emission
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.

Silicon-28

Silicon-28, the most abundant isotope of silicon, is of particular interest in the construction of quantum computers when highly enriched, as the presence of ²⁹Si in a sample of silicon contributes to quantum decoherence.^[6] Extremely pure (>99.9998%) samples of ²⁸Si can be produced through selective ionization and deposition of ²⁸Si from silane gas.^[7] Due to the extremely high purity that can be obtained in this manner, the Avogadro project sought to develop a new definition of the kilogram by making a 93.75 mm (3.691 in) sphere of the isotope and determing the exact number of atoms in the sample.^[8]^[9]

Silicon-28 is produced in stars during the alpha process and the oxygen-burning process, and drives the silicon-burning process in massive stars shortly before they go supernova.^[10]^[11]

Silicon-29

Silicon-29 is of note as the only stable silicon isotope with a nuclear spin (I = 1/2).^[12] As such, it can be employed in nuclear magnetic resonance and hyperfine transition studies, for example to study the properties of the so-called A-center defect in pure silicon.^[13]

Silicon-34

Silicon-34 is a radioactive isotope wth a half-life of 2.8 seconds.^[1] In addition to the usual N = 20 closed shell, the nucleus also shows a strong Z = 14 shell closure, making it behave like a doubly magic spherical nucleus, except that it is also located two protons above an island of inversion.^[14] Silicon-34 has an unusual "bubble" structure where the proton distribution is less dense at the center than near the surface, as the 2s_1/2 proton orbital is almost unoccupied in the ground state, unlike in ³⁶S where it is almost full.^[15]^[16] Silicon-34 is one of the known cluster decay emission particles; it is produced in the decay of ²⁴²Cm with a branching ratio of approximately 1×10⁻¹⁶.^[17]

References

^ ^a ^b ^c ^d ^e ^f ^g 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.
^ . CIAAW. 2009.
^
^
^ ^a ^b
^ . NIST. 2014-08-11.
^ . Journal of Physics D: Applied Physics. 47 (34): 345105. doi:10.1088/0022-3727/47/34/345105. ISSN 0022-3727.
^ Powell, Devin (1 July 2008). "Roundest Objects in the World Created". New Scientist. Retrieved 16 June 2015.
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^ . Physical Review. 121 (4): 1001–1014. doi:10.1103/PhysRev.121.1001. ISSN 0031-899X.
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External links

Silicon isotopes data from The Berkeley Laboratory Isotopes Project's

[4] Si – 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).

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[9] Modes of decay:

IT: Isomeric transition

n: Neutron emission

p: Proton emission

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

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

[NUBASE2020-1] ^ ^a ^b ^c ^d ^e ^f ^g 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] . CIAAW. 2009.

[CIAAW2021-3] ^

[AME2020_II-5] ^

[NR129-12] ^ ^a ^b

[13] . NIST. 2014-08-11.

[14] . Journal of Physics D: Applied Physics. 47 (34): 345105. doi:10.1088/0022-3727/47/34/345105. ISSN 0022-3727.

[15] Powell, Devin (1 July 2008). "Roundest Objects in the World Created". New Scientist. Retrieved 16 June 2015.

[Wired-16] ^

[WoosleyJanka-17] ^

[narlikar-18] ^

[19] ^

[20] . Physical Review. 121 (4): 1001–1014. doi:10.1103/PhysRev.121.1001. ISSN 0031-899X.

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