Isotopes of nitrogen

Natural nitrogen (₇N) consists of two stable isotopes: the vast majority (99.6%) of naturally occurring nitrogen is nitrogen-14, with the remainder being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, along with three nuclear isomers. All of these radioisotopes are short-lived, the longest-lived being nitrogen-13 with a half-life of 9.965(4) min. All of the others have half-lives below 7.15 seconds, with most of these being below 620 milliseconds. Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of 143(36) yoctoseconds, though the half-life of nitrogen-9 has not been measured exactly.

Isotopes of nitrogen (₇N)

Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 13N trace 9.965 min β+ 13C 14N 99.6% stable 15N 0.4% stable 16N synth 7.13 s β− 16O β−α<0.01% 12C
Standard atomic weight Ar°(N)
	[14.00643, 14.00728][1] 14.007±0.001 (abridged)[2]
view talk edit

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[3] [n 2][n 3]	Half-life[4] [resonance width]	Decay mode[4] [n 4]	Daughter isotope [n 5]	Spin and parity[4] [n 6][n 7]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion[4]	Range of variation
9 N [5]	7	2		<1 as[5]	5p[n 8]	4 He
10 N	7	3	10.04165(43)	143(36) ys	p ?[n 9]	9 C  ?	1−, 2−
11 N	7	4	11.026158(5)	585(7) ys [780.0(9.3) keV]	p	10 C	1/2+
11m N	740(60) keV			690(80) ys	p		1/2−
12 N	7	5	12.0186132(11)	11.000(16) ms	β+ (98.07(4)%)	12 C	1+
					β+α (1.93(4)%)	8 Be [n 10]
13 N [n 11]	7	6	13.00573861(29)	9.965(4) min	β+	13 C	1/2−
14 N [n 12]	7	7	14.003074004251(241)	Stable			1+	[0.99578, 0.99663][6]
14m N	2312.590(10) keV				IT	14 N	0+
15 N	7	8	15.000108898266(625)	Stable			1/2−	[0.00337, 0.00422][6]
16 N	7	9	16.0061019(25)	7.13(2) s	β− (99.99846(5)%)	16 O	2−
					β−α (0.00154(5)%)	12 C
16m N	120.42(12) keV			5.25(6) μs	IT (99.999611(25)%)	16 N	0−
					β− (0.000389(25)%)	16 O
17N	7	10	17.008449(16)	4.173(4) s	β−n (95.1(7)%)	16 O	1/2−
					β− (4.9(7)%)	17 O
					β−α (0.0025(4)%)	13 C
18 N	7	11	18.014078(20)	619.2(1.9) ms	β− (80.8(1.6)%)	18 O	1−
					β−α (12.2(6)%)	14 C
					β−n (7.0(1.5)%)	17 O
					β−2n ?[n 9]	16 O  ?
19 N	7	12	19.017022(18)	336(3) ms	β− (58.2(9)%)	19 O	1/2−
					β−n (41.8(9)%)	18 O
20 N	7	13	20.023370(80)	136(3) ms	β− (57.1(1.4)%)	20 O	(2−)
					β−n (42.9(1.4)%)	19 O
					β−2n ?[n 9]	18 O  ?
21 N	7	14	21.02709(14)	85(5) ms	β−n (87(3)%)	20 O	(1/2−)
					β− (13(3)%)	21 O
					β−2n ?[n 9]	19 O  ?
22 N	7	15	22.03410(22)	23(3) ms	β− (54.0(4.2)%)	22 O	0−#
					β−n (34(3)%)	21 O
					β−2n (12(3)%)	20 O
23 N [n 13]	7	16	23.03942(45)	13.9(1.4) ms	β− (> 46.6(7.2)%)	23 O	1/2−#
					β−n (42(6)%)	22 O
					β−2n (8(4)%)	21 O
					β−3n (< 3.4%)	20 O
This table header & footer: view

1. ^mN – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Modes of decay:

   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

5. Bold symbol as daughter – Daughter product is stable.
6. ( ) spin value – Indicates spin with weak assignment arguments.
7. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
8. Decays by proton emission to ⁸
   C
   , which immediately emits two protons to form ⁶
   Be
   , which in turn emits two protons to form stable ⁴
   He
   ^[5]
9. Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
10. Immediately decays into two alpha particles for a net reaction of ¹²N → 3 ⁴He + e⁺.
11. Used in positron emission tomography
12. One of the few stable odd-odd nuclei
13. Heaviest particle-bound isotope of nitrogen, see Nuclear drip line

Nitrogen-13

Main article: Nitrogen-13

Nitrogen-13 and oxygen-15 are produced in the atmosphere when gamma rays (for example from lightning) knock neutrons out of nitrogen-14 and oxygen-16:

¹⁴N + γ → ¹³N + n

¹⁶O + γ → ¹⁵O + n

The nitrogen-13 produced as a result decays with a half-life of 9.965(4) min to carbon-13, emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with a half-life of ten minutes, but these low-energy gamma rays go only about 90 metres through the air on average, so they may only be detected for a minute or so as the "cloud" of ¹³N and ¹⁵O floats by, carried by the wind.^[7]

Nitrogen-14

Nitrogen-14 makes up about 99.636% of natural nitrogen.

Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each) and is the only one to make up a majority of its element. Each proton or neutron contributes a nuclear spin of plus or minus spin 1/2, giving the nucleus a total magnetic spin of one.

The original source of nitrogen-14 and nitrogen-15 in the Universe is believed to be stellar nucleosynthesis, where they are produced as part of the CNO cycle.

Nitrogen-14 is the source of naturally-occurring, radioactive, carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14, which decays back to nitrogen-14 with a half-life of 5700(30) years.

Nitrogen-15

Nitrogen-15 is a rare stable isotope of nitrogen. Two sources of nitrogen-15 are the positron emission of oxygen-15^[8] and the beta decay of carbon-15. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes.^[9]

Nitrogen-15 is frequently used in NMR (Nitrogen-15 NMR spectroscopy). Unlike the more abundant nitrogen-14, which has an integer nuclear spin and thus a quadrupole moment, ¹⁵N has a fractional nuclear spin of one-half, which offers advantages for NMR such as narrower line width.

Nitrogen-15 tracing is a technique used to study the nitrogen cycle.

Nitrogen-16

The radioisotope ¹⁶N is the dominant radionuclide in the coolant of pressurised water reactors or boiling water reactors during normal operation. It is produced from ¹⁶O (in water) via an (n,p) reaction, in which the ¹⁶O atom captures a neutron and expels a proton. It has a short half-life of about 7.1 s,^[4] but its decay back to ¹⁶O produces high-energy gamma radiation (5 to 7 MeV).^[4][10] Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation.^[10] It is a sensitive and immediate indicator of leaks from the primary coolant system to the secondary steam cycle and is the primary means of detection for such leaks.^[10]

Isotopic signatures

Main article: Isotopic signature § Nitrogen isotopes

References

1. "Standard Atomic Weights: Nitrogen". CIAAW. 2009.
2. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
3. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
4. 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.
5. Cho, Adrian (25 September 2023). "Fleeting form of nitrogen stretches nuclear theory to its limits". science.org. Retrieved 27 September 2023.
6. "Atomic Weight of Nitrogen | Commission on Isotopic Abundances and Atomic Weights". ciaaw.org. Retrieved 2022-02-26.
7. Teruaki Enoto; et al. (Nov 23, 2017). "Photonuclear reactions triggered by lightning discharge". Nature. 551 (7681): 481–484. arXiv:1711.08044. Bibcode:2017Natur.551..481E. doi:10.1038/nature24630. PMID 29168803. S2CID 4388159.
8. CRC Handbook of Chemistry and Physics (64th ed.). 1983–1984. p. B-234.
9. "Evaluated Nuclear Data File (ENDF) Retrieval & Plotting". National Nuclear Data Center.
10. Neeb, Karl Heinz (1997). The Radiochemistry of Nuclear Power Plants with Light Water Reactors. Berlin-New York: Walter de Gruyter. p. 227. ISBN 978-3-11-013242-7. Archived from the original on 2016-02-05. Retrieved 2015-12-20.