Isotopes of nitrogen

Isotopes of nitrogen  (₇N)

Main isotopes [1] Decay Isotope abun­dance half-life (t1/2) mode pro­duct 13N trace 9.965 min β+ 13C 14N 99.6% stable 15N 0.380% stable 16N synth 7.13 s β− 16O β−α<0.01% 12C
Standard atomic weight Ar°(N)
	[14.00643, 14.00728] [2] 14.007±0.001 (abridged) [3]
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Natural nitrogen (₇N) consists of two stable isotopes: the vast majority (99.62%) of naturally occurring nitrogen is nitrogen-14, with the remainder (0.38%) 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 ¹³N with a half-life of 9.965(4) min. All of the others have half-lives shorter than ten seconds. Isotopes lighter than the stable ones generally decay to isotopes of carbon, and those heavier beta decay to isotopes of oxygen.

Nitrogen-13 is a positron emitter and one of the main isotopes used in medical PET scans.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [4] [n 2] [n 3]	Half-life [1] [resonance width]	Decay mode [1] [n 4]	Daughter isotope [n 5]	Spin and parity [1] [n 6] [n 7]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion [1]	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  ?	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 9]
13 N [n 10]	7	6	13.00573861(29)	9.965(4) min	β+	13 C	1/2−
14 N [n 11]	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 ?	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 ?	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 ?	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 12]	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
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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. Immediately decays into two alpha particles for a net reaction of ¹²N → 3 ⁴He + e⁺.
10. Used in positron emission tomography
11. One of the few stable odd-odd nuclei
12. 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 the clear majority of natural nitrogen, about 99.62%, and is responsible for the Earth's stable atmosphere.

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. Unpaired protons or neutrons contribute a half-integer nuclear spin, which in this case is a spin 1/2 orbital, giving the nucleus a total magnetic spin of one (as the spins prefer to align).

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 years.

Nitrogen-15

Nitrogen-15 is a rare stable isotope of nitrogen, comprising about 0.38%. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes. ^[8]

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. As most nitrogen NMR studies look at a single nitrogen atom in an organic molecule, isotopic labeling is feasible.

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

Nitrogen-16

The radioisotope ¹⁶N is the dominant radioactivity source in the coolant water of nuclear reactors cooled by water 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 7.13 seconds, but its decay back to ¹⁶O produces high-energy gamma radiation (6.13 MeV principal line ^[9] ). ^[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

See also

Daughter products other than nitrogen

• Isotopes of oxygen
• Isotopes of carbon
• Isotopes of beryllium
• Isotopes of helium

References

1. 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.
2. "Standard Atomic Weights: Nitrogen". CIAAW. 2009.
3. 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.
4. 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.
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. "Evaluated Nuclear Data File (ENDF) Retrieval & Plotting". National Nuclear Data Center.
9. National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
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.