碳的同位素

**主要的碳同位素**
标准原子质量 (Ar, 标准)	[12.0096, 12.0116]; 传统: 12.011;
←B（5）	N（7）→
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碳（原子量：12.0107(8)）共有15个已知同位素，其中有2个（¹²C与¹³C）是稳定的，其他都具有放射性。¹⁴C是碳唯一的天然放射性同位素，在宇宙线作用下发生¹⁴N + ¹n → ¹⁴C + ¹H反应而产生，半衰期为5700年。

常见的碳同位素

碳-11

碳-11是碳的一个放射性同位素，会衰变为硼-11，半衰期约20.334分钟。绝大多数的碳-11会透过β⁺衰变衰变为硼-11，其过程会发射出正子，而有少部分的(约0.19–0.23%)的碳-11会透过电子捕获衰变为硼-11^[2]^[3]。

¹¹C → ¹¹B + e⁺ + ν_e + 0.96 MeV

¹¹C + e⁻ → ¹¹B + ν_e + 1.98 MeV

碳-11可以利用氮透过粒子加速器以下列反应制备：

¹⁴N + p → ¹¹C + ⁴He

正电子发射计算机断层扫描中的放射线标记分子通常会使用含有放射性碳同位素碳-11的放射性分子，例如[¹¹C]DASB^[4]和[¹¹C]Cimbi-5^[5]^[6]。

图表

符号	Z（p ）	N（n ）	同位素质量（u）	半衰期	衰变方式^[7]	衰变产物^{[n 1]}	原子核自旋	相对丰度（摩尔分率）	相对丰度的变化量（摩尔分率）
⁸C	6	2	8.037675(25)	2.0(4) × 10⁻²¹ s [230(50) keV]	2p	⁶Be^{[n 2]}	0+
⁹C	6	3	9.0310367(23)	126.5(9) ms	β⁺ (60%)	⁹B^{[n 3]}	(3/2−)
					β⁺, p (23%)	⁸Be^{[n 4]}
					β⁺, α (17%)	⁵Li^{[n 5]}
¹⁰C	6	4	10.0168532(4)	19.290(12) s	β⁺	¹⁰B	0+
¹¹C^{[n 6]}	6	5	11.0114336(10)	20.334(24) min	β⁺ (99.79%)	¹¹B	3/2−
¹¹C^{[n 6]}	6	5	11.0114336(10)	20.334(24) min	ε (.21%)^[2]^[3]	¹¹B	3/2−
¹²C	6	6	12 确定的整数^{[n 7]}	稳定			0+	0.9893(8)	0.98853–0.99037
¹³C^{[n 8]}	6	7	13.0033548378(10)	稳定			1/2−	0.0107(8)	0.00963–0.01147
¹⁴C^{[n 9]}	6	8	14.003241989(4)	5,730 years	β⁻	¹⁴N	0+	痕量^{[n 10]}或天然放射性	<10⁻¹²
¹⁵C	6	9	15.0105993(9)	2.449(5) s	β⁻	¹⁵N	1/2+
¹⁶C	6	10	16.014701(4)	0.747(8) s	β⁻, n (97.9%)	¹⁵N	0+
¹⁶C	6	10	16.014701(4)	0.747(8) s	β⁻ (2.1%)	¹⁶N	0+
¹⁷C	6	11	17.022586(19)	193(5) ms	β⁻ (71.59%)	¹⁷N	(3/2+)
¹⁷C	6	11	17.022586(19)	193(5) ms	β⁻, n (28.41%)	¹⁶N	(3/2+)
¹⁸C	6	12	18.02676(3)	92(2) ms	β⁻ (68.5%)	¹⁸N	0+
¹⁸C	6	12	18.02676(3)	92(2) ms	β⁻, n (31.5%)	¹⁷N	0+
¹⁹C^{[n 11]}	6	13	19.03481(11)	46.2(23) ms	β⁻, n (47.0%)	¹⁸N	(1/2+)
					β⁻ (46.0%)	¹⁹N
					β⁻, 2n (7%)	¹⁷N
²⁰C	6	14	20.04032(26)	16(3) ms [14(+6-5) ms]	β⁻, n (72.0%)	¹⁹N	0+
²⁰C	6	14	20.04032(26)	16(3) ms [14(+6-5) ms]	β⁻ (28.0%)	²⁰N	0+
²¹C	6	15	21.04934(54)#	<30 ns	n	²⁰C	(1/2+)#
²²C^{[n 12]}	6	16	22.05720(97)#	6.2(13) ms [6.1(+14-12) ms]	β⁻	²²N	0+

备注：画上#号的数据代表没有经过实验的证明，只是理论推测而已，而用括号括起来的代表数据不确定性。

←	同位素列表	→
硼的同位素	碳的同位素	氮的同位素

注释

↑ Bold for stable isotopes
↑ Subsequently decays by double proton emission to ⁴He for a net reaction of ⁸C -> ⁴He + 4¹H
↑ Immediately decays by proton emission to ⁸Be, which immediately decays to two ⁴He atoms for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺
↑ Immediately decays into two ⁴He atoms for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺
↑ Immediately decays by proton emission to ⁴He for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺
↑ Used for labeling molecules in 正电子发射计算机断层扫描
↑ The 原子质量单位 is defined as 1/12 the mass of an unbound atom of carbon-12 at ground state
↑ [[:Ratio of ¹²C to ¹³C|Ratio of ¹²C to ¹³C]] used to measure biological productivity in ancient times and differing types of 光合作用
↑ Has an important use in 放射性定年法 (see 放射性碳定年法)
↑ Primarily cosmogenic, produced by 中子s striking atoms of ¹⁴N (¹⁴N + ¹n -> ¹⁴C + ¹H)
↑ Has 1 halo neutron
↑ Has 2 halo neutrons

参考文献

↑ Meija, Juris; et al. Atomic weights of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry. 2016, 88 (3): 265–91. doi:10.1515/pac-2015-0305.
↑ ^2.0 ^2.1 Scobie, J.; Lewis, G. M. K-capture in carbon 11. Philosophical Magazine. 1 September 1957, 2 (21): 1089–1099 [27 March 2012]. Bibcode:1957PMag....2.1089S. doi:10.1080/14786435708242737.
↑ ^3.0 ^3.1 Campbell, J. L.; Leiper, W.; Ledingham, K. W. D.; Drever, R. W. P. The ratio of K-capture to positron emission in the decay of ¹¹C. Nuclear Physics A: 279–287. [27 March 2012]. Bibcode:1967NuPhA..96..279C. doi:10.1016/0375-9474(67)90712-9.
↑ Sudha Garg; Shankar R. Thopate; Richard C. Minton; Kimberly W. Black; Andrew J. H. Lynch; Pradeep K. Garg. 3-Amino-4-(2-((4-[18F]fluorobenzyl)methylamino)methylphenylsulfanyl)benzonitrile, an F-18 fluorobenzyl analogue of DASB: synthesis, in vitro binding, and in vivo biodistribution studies. Bioconjug Chem. September–October 2007, 18 (5): 1612–1618. PMID 17705553. doi:10.1021/bc070112g.
↑ Ettrup, A.; Palner, M.; Gillings, N.; Santini, M. A.; Hansen, M.; Kornum, B. R.; Rasmussen, L. K.; Nagren, K.; Madsen, J. Radiosynthesis and Evaluation of ¹¹C-CIMBI-5 as a 5-HT_2A Receptor Agonist Radioligand for PET. Journal of Nuclear Medicine. November 2010, 51 (11): 1763–1770 [2018-09-18]. PMID 20956470. doi:10.2967/jnumed.109.074021.
↑ Martin Hansen. Design and synthesis of selective serotonin receptor agonists for positron emission tomography imaging of the brain. Ph.D. Thesis. Det Farmaceutiske Fakultet, København. 16 December 2010 [2018-09-18].
↑ Universal Nuclide Chart. nucleonica. [2015-09-09].

Flannery, T 2005, The weather makers: the history & future of climate change, The Text Publishing Company, Melbourne, Australia. ISBN 1920885 84 6.
Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report) . Pure Appl. Chem. Vol. 75, No. 6, pp. 683–800, (2003) and Atomic Weights Revised (2005) .
Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties , Nuc. Phys. A 729, pp. 3–128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.

[8] Bold for stable isotopes

[9] Subsequently decays by double proton emission to ⁴He for a net reaction of ⁸C -> ⁴He + 4¹H

[10] Immediately decays by proton emission to ⁸Be, which immediately decays to two ⁴He atoms for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺

[11] Immediately decays into two ⁴He atoms for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺

[12] Immediately decays by proton emission to ⁴He for a net reaction of ⁹C -> 2⁴He + ¹H + e⁺

[13] Used for labeling molecules in 正电子发射计算机断层扫描

[14] The 原子质量单位 is defined as 1/12 the mass of an unbound atom of carbon-12 at ground state

[15] [[:Ratio of ¹²C to ¹³C|Ratio of ¹²C to ¹³C]] used to measure biological productivity in ancient times and differing types of 光合作用

[16] Has an important use in 放射性定年法 (see 放射性碳定年法)

[17] Primarily cosmogenic, produced by 中子s striking atoms of ¹⁴N (¹⁴N + ¹n -> ¹⁴C + ¹H)

[18] Has 1 halo neutron

[19] Has 2 halo neutrons

[CIAAW2013-1] Meija, Juris; et al. Atomic weights of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry. 2016, 88 (3): 265–91. doi:10.1515/pac-2015-0305.

[c11-2] 2.0 ^2.1 Scobie, J.; Lewis, G. M. K-capture in carbon 11. Philosophical Magazine. 1 September 1957, 2 (21): 1089–1099 [27 March 2012]. Bibcode:1957PMag....2.1089S. doi:10.1080/14786435708242737.

[c11-2-3] 3.0 ^3.1 Campbell, J. L.; Leiper, W.; Ledingham, K. W. D.; Drever, R. W. P. The ratio of K-capture to positron emission in the decay of ¹¹C. Nuclear Physics A: 279–287. [27 March 2012]. Bibcode:1967NuPhA..96..279C. doi:10.1016/0375-9474(67)90712-9.

[4] Sudha Garg; Shankar R. Thopate; Richard C. Minton; Kimberly W. Black; Andrew J. H. Lynch; Pradeep K. Garg. 3-Amino-4-(2-((4-[18F]fluorobenzyl)methylamino)methylphenylsulfanyl)benzonitrile, an F-18 fluorobenzyl analogue of DASB: synthesis, in vitro binding, and in vivo biodistribution studies. Bioconjug Chem. September–October 2007, 18 (5): 1612–1618. PMID 17705553. doi:10.1021/bc070112g.

[11C-CIMBI-5-5] Ettrup, A.; Palner, M.; Gillings, N.; Santini, M. A.; Hansen, M.; Kornum, B. R.; Rasmussen, L. K.; Nagren, K.; Madsen, J. Radiosynthesis and Evaluation of ¹¹C-CIMBI-5 as a 5-HT_2A Receptor Agonist Radioligand for PET. Journal of Nuclear Medicine. November 2010, 51 (11): 1763–1770 [2018-09-18]. PMID 20956470. doi:10.2967/jnumed.109.074021.

[6] Martin Hansen. Design and synthesis of selective serotonin receptor agonists for positron emission tomography imaging of the brain. Ph.D. Thesis. Det Farmaceutiske Fakultet, København. 16 December 2010 [2018-09-18].

[7] Universal Nuclide Chart. nucleonica. [2015-09-09].

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