Promethium-147

Properties and data of the isotope ¹⁴⁷Pm.

Contents

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Promethium-147 is a radioactive isotope of the element promethium. The atomic nucleus of the nuclide has 86 neutrons in addition to the 61 element-specific protons. The isotope is the only naturally occurring Pm isotope; it is very rare on Earth though; the total mass is estimated to be well under a kilogram.

There are two main sources of natural promethium: alpha decay of europium-151 and the spontaneous fission of uranium. The most stable Pm isotope, with a half-life of 17.7 years, is promethium-145, but the only isotope with practical uses is Pm-147. Since natural promethium is very rare, it is usually made synthetically by bombarding uranium-235 with thermal neutrons. Promethium-147 can also be made from neodymium-147, which rapidly decays to promethium-147.

Pm-147 is used as a beta particle source and as a fuel for radioisotope thermoelectric generators. Promethium-147 was also used in phosphor mixtures to illuminate the electrical switch tips on the Apollo Lunar Module and painted on the control panels of the Lunar Roving Vehicle (LRV) for the same purpose.

Due to the high level of radioactivity found however, the isotope is hardly used today.

General data

Name of the isotope:Promethium-147; Pm-147Symbol:¹⁴⁷Pm or 14761PmMass number A:147 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:86Isotopic mass:146.9151449(14) u (atomic weight of Promethium-147)Nuclide mass:146.8816841 u (calculated nuclear mass without electrons)Mass excess:-79.04202 MeVMass defect:1.307364828 u (per nucleus)Nuclear binding energy:1217.80249309 MeV (per nucleus)
8.2843707 MeV (average binding energy per nucleon)Separation energy:S_N = 7.659(4) MeV (first neutron)
S_P = 5.4054(5) MeV (first proton)Half-life:2.6234(4) aDecay constant λ:8.378269768121 × 10^-9 s^-1Specific activity α:34558301853544 Bq g^-1
934.00815820389 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μ_N) = + 2.58Year of discovery:1947

Radioactive Decay

Half-life T_½ = 2.6234(4) a respectively 8.27315424 × 10⁷ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁴⁷Sm	100 %	0.22406(29) MeV

The diagram below shows parent nuclides, artificial production and radioactive decay of the Pm-147 isotope.

Parent Nuclides

Direct parent isotope is: ¹⁴⁷Nd.

Occurrence

Comparison of the natural Promethium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Promethium Isotopic mixture	146.9151385 u	100 %
Isotope ¹⁴⁷Pm	146.9151449(14) u		2.6234(4) a	7/2+

NMR data

Nuclear magnetic properties of the NMR active Nuclide ¹⁴⁷Pm

Isotope:¹⁴⁷Pm-NMRQuantity:Does not occur in nature!Spin:7/2+Nuclearmagnetic moment
μ/μ_N:+ 2.58Gyromagnetic ratio γ:3.613 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 0.73714285714286Quadrupole moment Q:+ 0.74(20) barn (100 fm²)Resonance frequency:v₀ = 5.62 at 1 TRelative Sensitivity:0.04827 (H₀ = const.)
2.7714 (v₀ = const.)
[related to ¹H = 1.000]

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 86) and isobaric (same nucleon number A = 147) with Promethium-147. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 86	Isobar A = 147
48	¹³⁴Cd
49	¹³⁵In
50	¹³⁶Sn
51	¹³⁷Sb
52	¹³⁸Te
53	¹³⁹I
54	¹⁴⁰Xe	¹⁴⁷Xe
55	¹⁴¹Cs	¹⁴⁷Cs
56	¹⁴²Ba	¹⁴⁷Ba
57	¹⁴³La	¹⁴⁷La
58	¹⁴⁴Ce	¹⁴⁷Ce
59	¹⁴⁵Pr	¹⁴⁷Pr
60	¹⁴⁶Nd	¹⁴⁷Nd
61	¹⁴⁷Pm	¹⁴⁷Pm
62	¹⁴⁸Sm	¹⁴⁷Sm
63	¹⁴⁹Eu	¹⁴⁷Eu
64	¹⁵⁰Gd	¹⁴⁷Gd
65	¹⁵¹Tb	¹⁴⁷Tb
66	¹⁵²Dy	¹⁴⁷Dy
67	¹⁵³Ho	¹⁴⁷Ho
68	¹⁵⁴Er	¹⁴⁷Er
69	¹⁵⁵Tm	¹⁴⁷Tm
70	¹⁵⁶Yb
71	¹⁵⁷Lu
72	¹⁵⁸Hf
73	¹⁵⁹Ta
74	¹⁶⁰W
75	¹⁶¹Re
76	¹⁶²Os

External data and identifiers

Adopted Levels, Gammas:NuDat 147Pm

Literature and References

[1] - Chung-Sin Lee et al.:
Chemical study on the separation and purification of promethium-147.
In: Journal of Radioanalytical and Nuclear Chemistry, (1989), DOI 10.1007/BF02037697.

[2] - Kathleen Broderick, Rita Luskac, James Hinderer et al.:
Reactor production of promethium-147.
In: Applied Radiation and Isotopes, (2019), DOI 10.1016/j.apradiso.2018.10.025.