There are 22 known isotopes of the chemical element aluminium, as well as several nuclear isomers. The stable isotope 27Al (almost 100%) and the radioisotope 26Al (in traces, half-life approx. 720,000 years) occur in nature. All other isotopes are unstable with small half-lives of less than 7 minutes or much less.
The natural isotope composition (isotope ratio) of naturally occurring aluminum can vary to a greater or lesser extent.
Atomic Mass ma | Quantity | Half-life | Spin | |
Aluminium Isotopic mixture | 26,9815384 u | 100 % | ||
Isotope 26Al | 25,98689186(7) u | traces | 7.17(24) × 105 a | 5+ |
Isotope 27Al | 26,9815385(7) u | 100 % | stable | 5/2+ |
Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 |
Aluminium-21 | 2113Al | 8 | 21.02897(64) u [21.0218385 u] {26.98538 MeV} | (5/2+) | |
Aluminium-22 | 2213Al | 9 | 22.01954(43) u [22.0124085 u] {18.20139 MeV} | (4)+ | 22Si |
Aluminium-23 | 2313Al | 10 | 23.0072444(4) u [23.0001129 u] {6.74812 MeV} | 5/2+ | 23Si |
Aluminium-24 | 2413Al | 11 | 23.99994754(25) u [23.9928161 u] {-0.04887 MeV} | 4+ | 24Si |
Aluminium-24m | 24m13Al | 11 | 23.99994754(25) u [23.9928161 u] {-0.04887 MeV} | 1+ | |
Aluminium-25 | 2513Al | 12 | 24.99042831(7) u [24.9832968 u] {-8.91597 MeV} | 5/2+ | 25Si 26P 27S |
Aluminium-26 | 2613Al | 13 | 25.98689186(7) u [25.9797604 u] {-12.21015 MeV} | 5+ | 26Si 27P |
Aluminium-26m | 26m13Al | 13 | 25.98689186(7) u [25.9797604 u] {-12.21015 MeV} | 0+ | |
Aluminium-27 | 2713Al | 14 | 26.9815385(7) u [26.974407 u] {-17.19678 MeV} | 5/2+ | 27Mg 27Si 28P |
Aluminium-28 | 2813Al | 15 | 27.98191001(5) u [27.9747785 u] {-16.85072 MeV} | 3+ | 28Mg |
Aluminium-29 | 2913Al | 16 | 28.9804532(4) u [28.9733217 u] {-18.20773 MeV} | 5/2+ | 29Mg |
Aluminium-30 | 3013Al | 17 | 29.982968(3) u [29.9758365 u] {-15.86521 MeV} | 3+ | 30Mg |
Aluminium-31 | 3113Al | 18 | 30.9839498(24) u [30.9768183 u] {-14.95066 MeV} | 5/2(+) | 31Mg |
Aluminium-32 | 3213Al | 19 | 31.988084(8) u [31.9809525 u] {-11.09968 MeV} | 1+ | 32Mg 33Mg |
Aluminium-32m | 32m13Al | 19 | 31.988084(8) u [31.9809525 u] {-11.09968 MeV} | (4+) | |
Aluminium-33 | 3313Al | 20 | 32.990878(8) u [32.9837465 u] {-8.49709 MeV} | (5/2)+ | 33Mg 34Mg |
Aluminium-34 | 3413Al | 21 | 33.996779(3) u [33.9896475 u] {-3.00034 MeV} | (4-) | 34Mg |
Aluminium-35 | 3513Al | 22 | 34.999760(8) u [34.9926285 u] {-0.22356 MeV} | (5/2+) | |
Aluminium-36 | 3613Al | 23 | 36.00639(16) u [35.9992585 u] {5.95225 MeV} | ||
Aluminium-37 | 3713Al | 24 | 37.01053(19) u [37.0033985 u] {9.80863 MeV} | 5/2+ | |
Aluminium-38 | 3813Al | 25 | 38.0174(4) u [38.0102685 u] {16.208 MeV} | (0-) | |
Aluminium-39 | 3913Al | 26 | 39.02217(43) u [39.0150385 u] {20.65122 MeV} | (5/2+) | |
Aluminium-40 | 4013Al | 27 | 40.02962(43) u [40.0224885 u] {27.59085 MeV} | ||
Aluminium-41 | 4113Al | 28 | 41.03588(54) u [41.0287485 u] {33.422 MeV} | 5/2+ | |
Aluminium-42 | 4213Al | 29 | 42.04305(64) u [42.0359185 u] {40.10082 MeV} | ||
Aluminium-43 | 4313Al | 30 | 43.05048(86) u [43.0433485 u] {47.02182 MeV} |
Isotope | Radioactive Decay | Extern | |||
---|---|---|---|---|---|
Half-life | Decay Mode | Probability | Energy | ||
7 | 8 | 9 | 10 | 11 | 12 |
Al-21 | 35 ns | p → 20Mg | ? | AL | |
Al-22 | 91.1(5) ms | β+ → 22Mg β+, p → 21Na β+, 2p → 20Ne β+, α → 18Ne | 43.862 % 55 % 1.1 % 0.038 % | 18.6(4) MeV | AL |
Al-23 | 470(30) ms | EC/β+ → 23Mg β+, p → 22Na | 95.54 % 0.46 % | 12.2216(4) MeV | AL |
Al-24 | 2.053(4) s | EC/β+ → 24Mg β+, p → 23Na β+, α → 20Ne | 99.96 % 0.0016 % 0.035 % | 13.88470(23) MeV 2.184 MeV 4.560 MeV | AL |
Al-24m | 130(3) ms | EC/β+ → 24Mg ε, α → 20Ne Iso → 24Al | 17.5(30) % 0.028(6) % 82.5(30) % | 14.302 MeV 4.986 MeV 0.426 MeV | AL |
Al-25 | 7.183(12) s | EC/β+ → 25Mg | 100 % | 4.27681(8) MeV | AL |
Al-26 | 7.17(24) × 105 a | EC β+ → 26Mg | 100 % | 4.00439(7) MeV | AL |
Al-26m | 6.3460(8) s | EC β+ → 26Mg | 100 % | 4.233 MeV | AL |
Al-27 | stable | AL | |||
Al-28 | 2.245(2) min | β- → 28Si | 100 % | 4.64208(5) MeV | AL |
Al-29 | 6.56(6) min | β- → 29Si | 100 % | 3.687(3) MeV | AL |
Al-30 | 3.62(6) s | β- → 30Si | 100 % | 8.5681(29) MeV | AL |
Al-31 | 644(25) ms | β- → 31Si β-, n → 30Si | 98.4 % 1.6 % | 7.9983(22) MeV 1.4109(22) MeV | AL |
Al-32 | 33.0(2) ms | β- → 32Si β-, n → 31Si | 99.3(5) % 0.7(5) % | 12.978(7) MeV 3.778(7) MeV | AL |
Al-32m | 200(20) ns | Iso → 32Al | 100 % | AL | |
Al-33 | 41.7(2) ms | β- → 33Si β-, n → 32Si | 91.5(5) % 8.5(7) % | 12.017(7) MeV 7.509(7) MeV | AL |
Al-34 | 56.3(5) ms | β- → 34Si β-, n → 33Si | 74(4) % 26(4) % | 16.957(14) MeV 9.443(3) MeV | AL |
Al-35 | 38.3(4) ms | β- → 35Si β-, n → 34Si | 62(2) % 38(2) % | 14.14057 MeV 11.6656 MeV | AL |
Al-36 | 90(40) ms | β- → 36Si β-, n → 35Si | > 69 % < 31 % | 18.3680 MeV 12.2395 MeV | AL |
Al-37 | 10.7(13) ms | β- → 37Si β-, n → 36Si | 100 % ? | 16.38(21) MeV 14.17(19) MeV | AL |
Al-38 | 9.0(7) ms | β- → 38Si β-, n → 37Si β-, 2n → 36Si | ? ? ? | 20.38(39) MeV 14.71(39) MeV | AL |
Al-39 | 7.6(16) ms | β- → 39Si β-, n 38Si β-, 2n 37Si | 100 % ? ? | 18.33(42) MeV 16.75(41) MeV | AL |
Al-40 | 260 ns | β- → 40Si β-, n 39Si β-, 2n 38Si | 100 % ? ? | 22.16(53) MeV 17.20(42) MeV | AL |
Al-41 | > 260 ns | β- → 41Si β-, n → 40Si | 100 % ? | 21.30(75) MeV 19.92(61) MeV | AL |
Al-42 | 170 ns | β- → 42Si β-, n → 41Si β-, 2n → 40Si | ? ? ? | 23.663(78) MeV 19.91(82) MeV | AL |
Al-43 | 170 ns | β- → 43Si β-, n → 42Si β-, 2n → 41Si | ? ? ? | 23.92(10) MeV 22.48(94) MeV | AL |
Notes (related to the columns):
1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Aluminium 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.
5 - nuclear spin I, unit: h/2π.
6 - 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.
7 - isotope notation in short form.
8 - decay: half-live of the Aluminium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: 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.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - 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.
Nuclide quantity 1) spin | Nuclear magnetic moment μ/μN | Gyromagnetic ratio {Quadrupole moment} | Resonant frequency v0 bei 1 T | Relative sensitivity H0 = const. v0 = const. 3) |
---|---|---|---|---|
27Al 100 % 5/2+ | +3,64070(2) | 6,976 {+ 0,1466(10)} | 11,1031 | 0,20689 3,0424 |
1) Quantity Percentage of natural occurrence.
2) Gyromagnetic ratio: 107 rad T-1 s-1
Quadrupole moment: Q [barn] = [100 fm2]
3) Related to 1H = 1,000.
According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Aluminium radionuclides:
Nuclide | Limit Value | HASS limit | SC | Daughter Nuclides | Half-life | |
---|---|---|---|---|---|---|
Al-26 | 105 Bq | 10 Bq/g | 0,03 TBq | 720000 a |
(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)
Properties of the Aluminium 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.
Aluminium: NMR properties - 27Al-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.
Last update: 2022-11-24
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