Oxygen-15

Properties and data of the isotope ¹⁵O.

Contents

Oxygen-15 is a radioisotope of the chemical element oxygen, which has 7 neutrons in its atomic nucleus in addition to the element-specific 8 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 15.

The discovery of the radioactive nuclide was reported in 1934. According to this, ¹⁵O was created by irradiating Nitrogen gas, which consists of more than 99.5% nitrogen-14, with deuterons - hydrogen-2 nuclei that were accelerated to 2 MeV in a cyclotron [1]:

¹⁴N(²H,n)¹⁵O.

Other typical methods for producing the radioactive isotope include [2]:

¹⁶O(γ,n)¹⁵O,

¹⁵N(p,n)¹⁵O und

¹⁶O(p,pn)¹⁵O.

These nuclear reactions to form ¹⁵O also occur under the influence of cosmic radiation or lightning in the atmosphere.

In practice, oxygen-15 is used as a medical radionuclide in positron emission tomography (PET) in the form of substances labelled with ¹⁵O, such as H₂¹⁵O or ¹⁵O₂ for brain and myocardial perfusion diagnostics.

General data

Name of the isotope:Oxygen-15; O-15Symbol:¹⁵O or 158OMass number A:15 (= number of nucleons)Atomic number Z:8 (= number of protons)Neutrons N:7Isotopic mass:15.0030656(5) u (atomic weight of Oxygen-15)Nuclide mass:14.998677 u (calculated nuclear mass without electrons)Mass excess:2.85559 MeVMass defect:0.120189068 u (per nucleus)Nuclear binding energy:111.95539571 MeV (per nucleus)
7.46369305 MeV (average binding energy per nucleon)Separation energy:S_N = 13.2235(5) MeV (first neutron)
S_P = 7.2968(5) MeV (first proton)Half-life:122.24(16) sDecay constant λ:0.00567037942212 s^-1Specific activity α:2.276521573952 × 10⁺²⁰ Bq g^-1
6152761010.6835 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Isobaric spin: 1/2Magnetic dipole moment:μ(μ_N) = 0.71908(12)Nuclear g-factor:g_l = 1.43816Mirror nucleus:Nitrogen-15Year of discovery:1934

Radioactive Decay

Oxygen-15 is a positron emitter that radioactively decays into nitrogen-15. After the positron is emitted, it quickly collides with an electron; both annihilate by emitting two gamma rays of 511 keV (annihilation radiation).

Half-life T_½ = 122.24(16) s respectively 1.2224 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	Details	γ energy (intensity)
EC β⁺	¹⁵N	100 %	2.7542(5) MeV	β⁺: 0.73528(23) MeV [99.9003(10) %] Annihilation: 0.511 MeV [199.8006(10) %]

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 7) and isobaric (same nucleon number A = 15) with Oxygen-15. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 7	Isobar A = 15
2	⁹He
3	¹⁰Li
4	¹¹Be	¹⁵Be
5	¹²B	¹⁵B
6	¹³C	¹⁵C
7	¹⁴N	¹⁵N
8	¹⁵O	¹⁵O
9	¹⁶F	¹⁵F
10	¹⁷Ne	¹⁵Ne
11	¹⁸Na
12	¹⁹Mg

Data changes (history)

Other sources give a half-life for ¹⁵O of 122,24(16) s. A more recent value was adopted here [NUBASE2020].

External data and identifiers

Adopted Levels, Gammas:NuDat 15O

Literature and References

[1] - M. Stanley Livingston, Edwin McMillan:
The Production of Radioactive Oxygen.
In: Physical Review, 46, 437, (1934), DOI 10.1103/PhysRev.46.437.2.

[2] - Stacy L. Queern et al.:
Production of ¹⁵O for Medical Applications via the ¹⁶O(γ,n)¹⁵O Reaction.
In: Radiochemistry, 60 (3), (2019), DOI 10.2967/jnumed.118.215681.

[3] - Teemu Maaniitty et al.:
15O-Water PET MPI: Current Status and Future Perspectives.
In: Seminars in Nuclear Medicine, 50, 3, (2020), DOI 10.1053/j.semnuclmed.2020.02.011.