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Isotopes of Silicon

List, data and properties of all known isotopes of Silicon as well as radioactive decay products and intermediate products.

 

Silicon isotopes

Of the 23 known isotopes of silicon, only the isotopes 28Si, 29Si and 30Si are stable and found in nature; all others are radioisotopes. 32Si is formed in the atmosphere by the action of cosmic rays on argon atoms and decays to phosphorus-31 with a half-life of 153 years.

 

Naturally Occurring Silicon Isotopes

Atomic Mass maQuantityHalf-lifeSpin
Silicon
Isotopic mixture
28,085 u100 %
Isotope 28Si27,976926535(3) u92,254 %stable0+
Isotope 29Si28,976494665(3) u4,673 %stable1/2+
Isotope 30Si29,97377001(2) u3,073 %stable0+

 

The natural isotopic abundances (isotopic ratio) of naturally occurring silicon can vary to a greater or lesser extent, so that the atomic mass fluctuates between 28.084 and 28.086.

< p>All other silicon radionuclides have half-lives in the range of seconds or much less.

The particularly stable silicon-28 core is created in stellar fusion processes during oxygen burning.

 

Isotope Table: Silicon

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
22Si14228Silicon-2222.03579(54) u
[22.02811 u]
{33.33817 MeV}
0+
23Si14239Silicon-2323.02544(54) u
[23.01776 u]
{23.69721 MeV}
(5/2)+
24Si142410Silicon-2424.011535(21) u
[24.003855 u]
{10.74478 MeV}
0+
25Si142511Silicon-2525.004108046(10735) u
[24.996428 u]
{3.82662 MeV}
5/2+
26Si142612Silicon-2625.9923338(12) u
[25.9846538 u]
{-7.14102 MeV}
0+26P
27Si142713Silicon-2726.98670469(12) u
[26.9790247 u]
{-12.3845 MeV}
5/2+0.8652(3)27P
28S
28Si142814Silicon-2827.976926535(3) u
[27.9692465 u]
{-21.49279 MeV}
0+28P
28Al
29S
31Ar
32Cl
29Si142915Silicon-2928.976494665(3) u
[28.9688146 u]
{-21.89508 MeV}
1/2+-0.555052(3)29P
29Al
30Si143016Silicon-3029.97377001(2) u
[29.96609 u]
{-24.43308 MeV}
0+30P
30Al
31Si143117Silicon-3130.97536319(5) u
[30.9676832 u]
{-22.94904 MeV}
3/2+31Al
32Si143218Silicon-3231.9741515(3) u
[31.9664715 u]
{-24.07772 MeV}
0+32Al
33Si143319Silicon-3332.9779770(8) u
[32.970297 u]
{-20.51429 MeV}
3/2+1.21(3)33Al
34Al
34Si143420Silicon-3433.978575(15) u
[33.970895 u]
{-19.95726 MeV}
0+34Al
35Al
35Si143521Silicon-3534.98455(4) u
[34.97687 u]
{-14.39158 MeV}
(7/2)-- 1.639(4)35Al
36Si143622Silicon-3635.98665(8) u
[35.97897 u]
{-12.43544 MeV}
0+
37Si143723Silicon-3736.99295(12) u
[36.98527 u]
{-6.56703 MeV}
(5/2-)
38Si143824Silicon-3837.99552(11) u
[37.98784 u]
{-4.17309 MeV}
0+
39Si143925Silicon-3939.00249(15) u
[38.99481 u]
{2.31942 MeV}
(5/2-)
40Si144026Silicon-4040.00583(37) u
[39.99815 u]
{5.43061 MeV}
0+
41Si144127Silicon-4141.01301(60) u
[41.00533 u]
{12.11874 MeV}
7/2-
42Si144228Silicon-4242.01768(54) u
[42.01 u]
{16.46881 MeV}
0+
43Si144329Silicon-4343.02480(64) u
[43.01712 u]
{23.10105 MeV}
3/2-
44Si144430Silicon-4444.03061(64) u
[44.02293 u]
{28.51303 MeV}
0+

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
Si-2229(2) msEC/β+22Al
β+, p → 21Mg
68(4) %
32(4) %
15.14(64) MeV
AL
Si-2342.3(4) msEC/β+23Al
ε, p → 22Mg
ε, 2p → 21Na
25.4 %
71 %
3.6 %
17.002 MeV
16.880 MeV
11.378 MeV
AL
Si-24140(8) msEC/β+24Al
β+, p → 23Mg
62(4) %
38(4) %
10.794(19) MeV
8.939 MeV
AL
Si-25220(3) msEC/β+25Al
β+, p → 24Mg
65(2) %
35(2) %
12.743(10) MeV
10.469 MeV
AL
Si-262.2453(7) sEC/β+26Al100 %5.06914(13) MeVAL
Si-274.15(4) sEC/β+27Al100 %4.81236 MeVAL
Si-28stableAL
Si-29stableAL
Si-30stableAL
Si-31157.36(26) minβ-31P100 %1.49150(4) MeVAL
Si-32153(19) aβ-32P100 %0.2272(3) MeVAL
Si-336.11(21) sβ-33P100 %5.8230(13) MeVAL
Si-342.77(20) sβ-34P100 %4.592(14) MeVAL
Si-350.78(12) sβ-35P
β-, n → 34P
> 95 %
< 5 %
10.4974 MeV
2.11698 MeV
AL
Si-360.45(6) sβ-36P
β-, n → 35P
> 90 %
< 10 %
7.83339 MeV
4.3688 MeV
AL
Si-3790(60) msβ-37P
β-, n → 36P
β-, 2n → 35P
83(13) %
17(13) %
?
12.4016 MeV
5.5854 MeV
AL
Si-3863(8) msβ-38P
β-, n → 37P
75(10) %
25(10) %
10.45(13) MeV
6.75(11) MeV
AL
Si-3947.5(20) msβ-39P
β-, n → 38P
β-, 2n → 37P
100 %
?
?
15.09(18) MeV
8.87(15) MeV
AL
Si-4033.0(10) msβ-40P
β-, n → 39P
β-, 2n → 38P
100 %
?
?
13.54(38) MeV
10.13(36) MeV
AL
Si-4120.0(25) msβ-41P
β-, n → 40P
100 %
> 0 %
17.10(57) MeV
12.16(58) MeV
AL
Si-4212.5(35) msβ-42P
β-, n → 41P
β-, 2n → 40P
100 %
?
?
15.46(59) MeV
13.38(51) MeV
AL
Si-4360 nsβ-43P
β-, n → 42P
β-, 2n → 41P
?
?
?
18.42(81) MeV
14.02(67) MeV
AL
Si-44360 nsβ-44P
β-, n → 43P
100 %
?
18.06(78) MeV
15.76(81) MeV
AL

 

Notes (related to the columns):

1 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Silicon isotope.
6 - Relative atomic mass of the Silicon isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
7 - Nuclear spin I, unit: h/2π.
8 - Nuclear magnetic moment μmag.
9 - Source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
10 - Decay: Half-live of the Silicon isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
11 - Decay: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
12 - Decay percentage in percent (%).
13 - Decay energy; Particle energy related to decay type.
14 - AE = Excitation energy for metastable nuclei.
15 - Other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

NMR active Silicon nuclides

Nuclide
quantity 1)
spin
Nuclear magnetic
moment
μ/μN
Gyromagnetic
ratio
107 rad T-1 s-1
Quadrupole
moment
Q fm-2
Resonant
frequency
v0 bei 1 T
Relative
sensitivity
H0 = const.
v0 = const. 2)
29Si
4,673 %
1/2+
-0,555052(3)- 5,31888,46550,00786
0,1988

1) Quantity Percentage of natural occurrence.

2) Related to 1H = 1,000.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Silicon radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Si-31106 Bq1000 Bq/g10 TBq100 Bq/cm22.6 h
Si-32+106 Bq100 Bq/g7 Bq132.0 a (s.o.)

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Silicon nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Silicon: NMR properties - 29Si-NMR

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

 


Category: Isotopes

Last update: 05.07.2020



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