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Standard atomic weight Ar°(Br) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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Bromine (35Br) has two stable isotopes, 79Br and 81Br, with nearly equal natural abundance, and 32 known artificial radioisotopes from 68Br to 101Br, the most stable of which is 77Br, with a half-life of 57.04 hours. This is followed by 82Br at 35.282 hours and 76Br at 16.2 hours; the most stable isomer is 80mBr with the half-life of 4.4205 hours.
Like the radioactive isotopes of iodine, radioisotopes of bromine, collectively radiobromine, can be used to label biomolecules for nuclear medicine; for example, the positron emitters 75Br and 76Br can be used for positron emission tomography. [4] [5] Radiobromine has the advantage that organobromides are more stable than analogous organoiodides, and that it is not uptaken by the thyroid like iodine. [6]
Nuclide [n 1] | Z | N | Isotopic mass (Da) [7] [n 2] [n 3] | Half-life [1] | Decay mode [1] [n 4] | Daughter isotope [n 5] [n 6] | Spin and parity [1] [n 7] [n 8] | Natural abundance (mole fraction) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy | Normal proportion [1] | Range of variation | |||||||||||||||||
67Br | 35 | 32 | |||||||||||||||||
68Br [8] | 35 | 33 | 67.95836(28)# | ~35 ns | p? | 67Se | 3+# | ||||||||||||
69Br | 35 | 34 | 68.950338(45) | <19 ns [8] | p | 68Se | (5/2−) | ||||||||||||
70Br | 35 | 35 | 69.944792(16) | 78.8(3) ms | β+ | 70Se | 0+ | ||||||||||||
β+, p? | 69As | ||||||||||||||||||
70mBr | 2292.3(8) keV | 2.16(5) s | β+ | 70Se | 9+ | ||||||||||||||
β+, p? | 69As | ||||||||||||||||||
71Br | 35 | 36 | 70.9393422(58) | 21.4(6) s | β+ | 71Se | (5/2)− | ||||||||||||
72Br | 35 | 37 | 71.9365946(11) | 78.6(24) s | β+ | 72Se | 1+ | ||||||||||||
72mBr | 100.76(15) keV | 10.6(3) s | IT | 72Br | (3−) | ||||||||||||||
β+? | 72Se | ||||||||||||||||||
73Br | 35 | 38 | 72.9316734(72) | 3.4(2) min | β+ | 73Se | 1/2− | ||||||||||||
74Br | 35 | 39 | 73.9299103(63) | 25.4(3) min | β+ | 74Se | (0−) | ||||||||||||
74mBr | 13.58(21) keV | 46(2) min | β+ | 74Se | 4+ | ||||||||||||||
75Br | 35 | 40 | 74.9258106(46) | 96.7(13) min | β+ (76%) [6] | 75Se | 3/2− | ||||||||||||
EC (24%) | 75Se | ||||||||||||||||||
76Br | 35 | 41 | 75.924542(10) | 16.2(2) h | β+ (57%) [6] | 76Se | 1− | ||||||||||||
EC (43%) | 76Se | ||||||||||||||||||
76mBr | 102.58(3) keV | 1.31(2) s | IT (>99.4%) | 76Br | (4)+ | ||||||||||||||
β+ (<0.6%) | 76Se | ||||||||||||||||||
77Br | 35 | 42 | 76.9213792(30) | 57.04(12) h | EC (99.3%) [9] | 77Se | 3/2− | ||||||||||||
β+ (0.7%) | 77Se | ||||||||||||||||||
77mBr | 105.86(8) keV | 4.28(10) min | IT | 77Br | 9/2+ | ||||||||||||||
78Br | 35 | 43 | 77.9211459(38) | 6.45(4) min | β+ (>99.99%) | 78Se | 1+ | ||||||||||||
β− (<0.01%) | 78Kr | ||||||||||||||||||
78mBr | 180.89(13) keV | 119.4(10) μs | IT | 78Br | (4+) | ||||||||||||||
79Br | 35 | 44 | 78.9183376(11) | Stable | 3/2− | 0.5065(9) | |||||||||||||
79mBr | 207.61(9) keV | 4.85(4) s | IT | 79Br | 9/2+ | ||||||||||||||
80Br | 35 | 45 | 79.9185298(11) | 17.68(2) min | β− (91.7%) | 80Kr | 1+ | ||||||||||||
β+ (8.3%) | 80Se | ||||||||||||||||||
80mBr | 85.843(4) keV | 4.4205(8) h | IT | 80Br | 5− | ||||||||||||||
81Br [n 9] | 35 | 46 | 80.9162882(10) | Stable | 3/2− | 0.4935(9) | |||||||||||||
81mBr | 536.20(9) keV | 34.6(28) μs | IT | 81Br | 9/2+ | ||||||||||||||
82Br | 35 | 47 | 81.9168018(10) | 35.282(7) h | β− | 82Kr | 5− | ||||||||||||
82mBr | 45.9492(10) keV | 6.13(5) min | IT (97.6%) | 82Br | 2− | ||||||||||||||
β− (2.4%) | 82Kr | ||||||||||||||||||
83Br | 35 | 48 | 82.9151753(41) | 2.374(4) h | β− | 83Kr | 3/2− | ||||||||||||
83mBr | 3069.2(4) keV | 729(77) ns | IT | 83Br | (19/2−) | ||||||||||||||
84Br | 35 | 49 | 83.9165136(17) [10] | 31.76(8) min | β− | 84Kr | 2− | ||||||||||||
84m1Br | 193.6(15) keV [10] | 6.0(2) min | β− | 84Kr | (6)− | ||||||||||||||
84m2Br | 408.2(4) keV | <140 ns | IT | 84Br | 1+ | ||||||||||||||
85Br | 35 | 50 | 84.9156458(33) | 2.90(6) min | β− | 85m1Kr [11] | 3/2− | ||||||||||||
86Br | 35 | 51 | 85.9188054(33) | 55.1(4) s | β− | 86Kr | (1−) | ||||||||||||
87Br | 35 | 52 | 86.9206740(34) | 55.68(12) s | β− (97.40%) | 87Kr | 5/2− | ||||||||||||
β−, n (2.60%) | 86Kr | ||||||||||||||||||
88Br | 35 | 53 | 87.9240833(34) | 16.34(8) s | β− (93.42%) | 88Kr | (1−) | ||||||||||||
β−, n (6.58%) | 87Kr | ||||||||||||||||||
88mBr | 270.17(11) keV | 5.51(4) μs | IT | 88Br | (4−) | ||||||||||||||
89Br | 35 | 54 | 88.9267046(35) | 4.357(22) s | β− (86.2%) | 89Kr | (3/2−, 5/2−) | ||||||||||||
β−, n (13.8%) | 88Kr | ||||||||||||||||||
90Br | 35 | 55 | 89.9312928(36) | 1.910(10) s | β− (74.7%) | 90Kr | |||||||||||||
β−, n (25.3%) | 89Kr | ||||||||||||||||||
91Br | 35 | 56 | 90.9343986(38) | 543(4) ms | β− (70.5%) | 91Kr | 5/2−# | ||||||||||||
β−, n (29.5%) | 90Kr | ||||||||||||||||||
92Br | 35 | 57 | 91.9396316(72) | 314(16) ms | β− (66.9%) | 92Kr | (2−) | ||||||||||||
β−, n (33.1%) | 91Kr | ||||||||||||||||||
β−, 2n? | 90Kr | ||||||||||||||||||
92m1Br | 662(1) keV | 88(8) ns | IT | 92Br | |||||||||||||||
92m2Br | 1138(1) keV | 85(10) ns | IT | 92Br | |||||||||||||||
93Br | 35 | 58 | 92.94322(46) | 152(8) ms | β−, n (64%) | 92Kr | 5/2−# | ||||||||||||
β− (36%) | 93Kr | ||||||||||||||||||
β−, 2n? | 91Kr | ||||||||||||||||||
94Br | 35 | 59 | 93.94885(22)# | 70(20) ms | β−, n (68%) | 93Kr | 2−# | ||||||||||||
β− (32%) | 94Kr | ||||||||||||||||||
β−, 2n? | 92Kr | ||||||||||||||||||
94mBr | 294.6(5) keV | 530(15) ns | IT | 94Br | |||||||||||||||
95Br | 35 | 60 | 94.95293(32)# | 80# ms [>300 ns] | β−? | 95Kr | 5/2−# | ||||||||||||
β−, n? | 94Kr | ||||||||||||||||||
β−, 2n? | 93Kr | ||||||||||||||||||
95mBr | 537.9(5) keV | 6.8(10) μs | IT | 95Br | |||||||||||||||
96Br | 35 | 61 | 95.95898(32)# | 20# ms [>300 ns] | β−? | 96Kr | |||||||||||||
β−, n? | 95Kr | ||||||||||||||||||
β−, 2n? | 94Kr | ||||||||||||||||||
96mBr | 311.5(5) keV | 3.0(9) μs | IT | 96Br | |||||||||||||||
97Br | 35 | 62 | 96.96350(43)# | 40# ms [>300 ns] | β−? | 97Kr | 5/2−# | ||||||||||||
β−, n? | 96Kr | ||||||||||||||||||
β−, 2n? | 95Kr | ||||||||||||||||||
98Br | 35 | 63 | 97.96989(43)# | 15# ms [>400 ns] | β−? | 98Kr | |||||||||||||
β−, n? | 97Kr | ||||||||||||||||||
β−, 2n? | 96Kr | ||||||||||||||||||
99Br [12] | 35 | 64 | |||||||||||||||||
100Br [12] | 35 | 65 | |||||||||||||||||
101Br [13] | 35 | 66 | |||||||||||||||||
This table header & footer: |
IT: | Isomeric transition |
n: | Neutron emission |
p: | Proton emission |
Bromine-75 has a half-life of 97 minutes. [14] This isotope undergoes positron emission rather than electron capture about 76% of the time, [6] so it was used for diagnosis and positron emission tomography (PET) in the 1980s. [4] However, its decay product, selenium-75, produces secondary radioactivity with a longer half-life of around 120 days. [6] [4]
Bromine-76 has a half-life of 16.2 hours. [14] While its decay is more energetic than 75Br and has a lower yield of positrons, about 57% of decays, [6] bromine-76 has been preferred in PET applications since the 1980s because of its longer half-life and easier synthesis, and because its decay product, 76Se, is not radioactive. [5]
Bromine-77 is the most stable radioisotope of bromine, with a half-life of 57.04 hours. [14] Although β+ decay is possible for this isotope, about 99.3% of decays are by electron capture. [9] Despite its complex emission spectrum, featuring strong gamma-ray emissions at 239, 297, 521, and 579 keV, [15] 77Br was used in SPECT imaging in the 1970s. [16] However, except for longer-term tracing, [6] this is no longer considered practical due to the difficult collimator requirements and the proximity of the 521 keV line to the 511 keV annihilation radiation related to the β+ decay. [16] The Auger electrons emitted during decay are nevertheless well-suited for radiotherapy, and 77Br can possibly be paired with the imaging-suited 76Br (produced as an impurity in common synthesis routes) for this application. [4] [16]
Daughter products other than bromine