Physics:Isotopes of nitrogen

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Short description: Isotopes of the element nitrogen
Main isotopes of Chemistry:nitrogen (7N)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
13N syn 9.965 min β+ 13C
14N 99.6% stable
15N 0.4% stable
Standard atomic weight Ar, standard(N)
  • [14.0064314.00728][1]
  • Conventional: 14.007
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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. Fourteen radioisotopes are also known, with atomic masses ranging from 10 to 25, along with one nuclear isomer, 11mN. 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.

List of isotopes

Nuclide
[n 1]
Z N Isotopic mass (u)
[n 2][n 3]
Half-life

[resonance width]
Decay
mode

[n 4]
Daughter
isotope

[n 5]
Spin and
parity
[n 6][n 7]
Physics:Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
10N 7 3 10.04165(43) 143(36) ys p ?[n 8] 9C ? 1−, 2−
11N 7 4 11.026158(5) 585(7) ys
[780.0(9.3) keV]
p 10C 1/2+
11mN 740(60) keV 690(80) ys p 1/2−
12N 7 5 12.0186132(11) 11.000(16) ms β+ (98.07(4)%) 12C 1+
β+α (1.93(4)%) 8Be[n 9]
13N[n 10] 7 6 13.00573861(29) 9.965(4) min β+ 13C 1/2−
14N[n 11] 7 7 14.003074004251(241) Stable 1+ [0.99578, 0.99663][2]
14mN 2312.590(10) keV IT 14N 0+
15N 7 8 15.000108898266(625) Stable 1/2− [0.00337, 0.00422][2]
16N 7 9 16.0061019(25) 7.13(2) s β (99.99846(5)%) 16O 2−
βα (0.00154(5)%) 12C
16mN 120.42(12) keV 5.25(6) μs IT (99.999611(25)%) 16N 0−
β (0.000389(25)%) 16O
17N 7 10 17.008449(16) 4.173(4) s βn (95.1(7)%) 16O 1/2−
β (4.9(7)%) 17O
βα (0.0025(4)%) 13C
18N 7 11 18.014078(20) 619.2(1.9) ms β (80.8(1.6)%) 18O 1−
βα (12.2(6)%) 14C
βn (7.0(1.5)%) 17O
β2n ?[n 8] 16O ?
19N 7 12 19.017022(18) 336(3) ms β (58.2(9)%) 19O 1/2−
βn (41.8(9)%) 18O
20N 7 13 20.023370(80) 136(3) ms β (57.1(1.4)%) 20O (2−)
βn (42.9(1.4)%) 19O
β2n ?[n 8] 18O ?
21N 7 14 21.02709(14) 85(5) ms βn (87(3)%) 20O (1/2−)
β (13(3)%) 21O
β2n ?[n 8] 19O ?
22N 7 15 22.03410(22) 23(3) ms β (54.0(4.2)%) 22O 0−#
βn (34(3)%) 21O
β2n (12(3)%) 20O
23N 7 16 23.03942(45) 13.9(1.4) ms β (> 46.6(7.2)%) 23O 1/2−#
βn (42(6)%) 22O
β2n (8(4)%) 21O
β3n (< 3.4%) 20O
24N 7 17 24.05039(43)# < 52 ns n ?[n 8] 23N ?
25N 7 18 25.06010(54)# < 260 ns n ?[n 8] 24N ? 1/2−#
2n ?[n 8] 23N ?
β ?[n 8] 25O ?
  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. 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
  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

Nitrogen-13

Main page: Physics: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.[3]

Nitrogen-14

Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes 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.

Like all elements heavier than lithium, 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 carbon-nitrogen-oxygen 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[4] and the beta decay of carbon-15. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes.[5]

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.

Isotopic signatures

References

  1. Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305. 
  2. 2.0 2.1 "Atomic Weight of Nitrogen | Commission on Isotopic Abundances and Atomic Weights". https://ciaaw.org/nitrogen.htm. 
  3. Teruaki Enoto (Nov 23, 2017). "Photonuclear reactions triggered by lightning discharge". Nature 551 (7681): 481–484. doi:10.1038/nature24630. PMID 29168803. Bibcode2017Natur.551..481E. 
  4. CRC Handbook of Chemistry and Physics (64th ed.). 1983–1984. p. B-234. 
  5. "Evaluated Nuclear Data File (ENDF) Retrieval & Plotting". National Nuclear Data Center. http://www.nndc.bnl.gov/sigma/index.jsp?as=15&lib=endfb7.1&nsub=10.