# Isotopes of nitrogen

Natural nitrogen ($_7$N) 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.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life [resonance width] | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life [resonance width] | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^9$ N | 7 | 2 | | <1 as | 5p | $^4$ 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 | 740(60) keV | 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+ | | |
| $^{12}$ N | 7 | 5 | 12.0186132(11) | 11.000(16) ms | β$^+$α (1.93(4)%) | $^8$ Be | 1+ | | |
| $^{13}$ N | 7 | 6 | 13.00573861(29) | 9.965(4) min | β$^+$ | $^{13}$ C | 1/2− | | |
| $^{14}$ N | 7 | 7 | 14.003074004251(241) | Stable | Stable | Stable | 1+ | [0.99578, 0.99663] | |
| $^{14m}$ N | 2312.590(10) keV | 2312.590(10) keV | 2312.590(10) keV | | IT | $^{14}$ N | 0+ | | |
| $^{15}$ N | 7 | 8 | 15.000108898266(625) | Stable | Stable | Stable | 1/2− | [0.00337, 0.00422] | |
| $^{16}$ N | 7 | 9 | 16.0061019(25) | 7.13(2) s | β$^−$ (99.99846(5)%) | $^{16}$ O | 2− | | |
| $^{16}$ N | 7 | 9 | 16.0061019(25) | 7.13(2) s | β$^−$α (0.00154(5)%) | $^{12}$ C | 2− | | |
| $^{16m}$ N | 120.42(12) keV | 120.42(12) keV | 120.42(12) keV | 5.25(6) μs | IT (99.999611(25)%) | $^{16}$ N | 0− | | |
| $^{16m}$ N | 120.42(12) keV | 120.42(12) keV | 120.42(12) keV | 5.25(6) μs | β$^−$ (0.000389(25)%) | $^{16}$ O | 0− | | |
| $^{17}$N | 7 | 10 | 17.008449(16) | 4.173(4) s | β$^−$n (95.1(7)%) | $^{16}$ O | 1/2− | | |
| $^{17}$N | 7 | 10 | 17.008449(16) | 4.173(4) s | β$^−$ (4.9(7)%) | $^{17}$ O | 1/2− | | |
| $^{17}$N | 7 | 10 | 17.008449(16) | 4.173(4) s | β$^−$α (0.0025(4)%) | $^{13}$ C | 1/2− | | |
| $^{18}$ N | 7 | 11 | 18.014078(20) | 619.2(1.9) ms | β$^−$ (80.8(1.6)%) | $^{18}$ O | 1− | | |
| $^{18}$ N | 7 | 11 | 18.014078(20) | 619.2(1.9) ms | β$^−$α (12.2(6)%) | $^{14}$ C | 1− | | |
| $^{18}$ N | 7 | 11 | 18.014078(20) | 619.2(1.9) ms | β$^−$n (7.0(1.5)%) | $^{17}$ O | 1− | | |
| $^{18}$ N | 7 | 11 | 18.014078(20) | 619.2(1.9) ms | β$^−$2n ? | $^{16}$ O ? | 1− | | |
| $^{19}$ N | 7 | 12 | 19.017022(18) | 336(3) ms | β$^−$ (58.2(9)%) | $^{19}$ O | 1/2− | | |
| $^{19}$ N | 7 | 12 | 19.017022(18) | 336(3) ms | β$^−$n (41.8(9)%) | $^{18}$ O | 1/2− | | |
| $^{20}$ N | 7 | 13 | 20.023370(80) | 136(3) ms | β$^−$ (57.1(1.4)%) | $^{20}$ O | (2−) | | |
| $^{20}$ N | 7 | 13 | 20.023370(80) | 136(3) ms | β$^−$n (42.9(1.4)%) | $^{19}$ O | (2−) | | |
| $^{20}$ N | 7 | 13 | 20.023370(80) | 136(3) ms | β$^−$2n ? | $^{18}$ O ? | (2−) | | |
| $^{21}$ N | 7 | 14 | 21.02709(14) | 85(5) ms | β$^−$n (87(3)%) | $^{20}$ O | (1/2−) | | |
| $^{21}$ N | 7 | 14 | 21.02709(14) | 85(5) ms | β$^−$ (13(3)%) | $^{21}$ O | (1/2−) | | |
| $^{21}$ N | 7 | 14 | 21.02709(14) | 85(5) ms | β$^−$2n ? | $^{19}$ O ? | (1/2−) | | |
| $^{22}$ N | 7 | 15 | 22.03410(22) | 23(3) ms | β$^−$ (54.0(4.2)%) | $^{22}$ O | 0−# | | |
| $^{22}$ N | 7 | 15 | 22.03410(22) | 23(3) ms | β$^−$n (34(3)%) | $^{21}$ O | 0−# | | |
| $^{22}$ N | 7 | 15 | 22.03410(22) | 23(3) ms | β$^−$2n (12(3)%) | $^{20}$ O | 0−# | | |
| $^{23}$ N | 7 | 16 | 23.03942(45) | 13.9(1.4) ms | β$^−$ (> 46.6(7.2)%) | $^{23}$ O | 1/2−# | | |
| $^{23}$ N | 7 | 16 | 23.03942(45) | 13.9(1.4) ms | β$^−$n (42(6)%) | $^{22}$ O | 1/2−# | | |
| $^{23}$ N | 7 | 16 | 23.03942(45) | 13.9(1.4) ms | β$^−$2n (8(4)%) | $^{21}$ O | 1/2−# | | |
| $^{23}$ N | 7 | 16 | 23.03942(45) | 13.9(1.4) ms | β$^−$3n (< 3.4%) | $^{20}$ O | 1/2−# | | |
| This table header & footer: view ||||||||||
* ↑ $^m$N – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Modes of decay: IT:Isomeric transition n:Neutron emission p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ 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
* 1 2 3 4 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
* ↑ Immediately decays into two alpha particles for a net reaction of $^{12}$N → 3 $^4$He + e$^+$.
* ↑ Used in positron emission tomography
* ↑ One of the few stable odd-odd nuclei
* ↑ Heaviest particle-bound isotope of nitrogen, see Nuclear drip line

## 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:
    $^{14}$N + γ → $^{13}$N + n
    $^{16}$O + γ → $^{15}$O + 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 $^{13}$N and $^{15}$O floats by, carried by the wind.

## 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 and the beta decay of carbon-15. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes.
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, $^{15}$N 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 $^{16}$N is the dominant radionuclide in the coolant of reactors refrigerated by water or boiling water reactors during normal operation. It is produced from $^{16}$O (in water) via an (n,p) reaction, in which the $^{16}$O atom captures a neutron and expels a proton. It has a short half-life of about 7.1 s, but its decay back to $^{16}$O produces high-energy gamma radiation (5 to 7 MeV). Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation. 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.