Samarium-147

Properties and data of the isotope ¹⁴⁷Sm.

Contents

General Data

Radioactive Decay

Parent Nuclides

Occurrence

NMR Data

Isotones und Isobares

Literature

Samarium-146 is a weakly radioactive isotope of the chemical element Samarium, which, in addition to the element-specific 62 protons, has 85 neutrons in the atomic nucleus, resulting in the mass number 147. With a half-life of around 106 billion years - several times the assumed age of our universe - the nuclide is considered quasi-stable.

General data

Name of the isotope:Samarium-147; Sm-147Symbol:¹⁴⁷Sm or 14762SmMass number A:147 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:85Isotopic mass:146.91490(2) u (atomic weight of Samarium-147)Nuclide mass:146.8808907 u (calculated nuclear mass without electrons)Mass excess:-79.27014 MeVMass defect:1.306769844 u (per nucleus)Nuclear binding energy:1217.24826907 MeV (per nucleus)
8.28060047 MeV (average binding energy per nucleon)Separation energy:S_N = 6.3410(28) MeV (first neutron)
S_P = 7.101(4) MeV (first proton)Half-life:1.0625(38) × 10¹¹ aDecay constant λ:1.371493380112 × 10^-19 s^-1Specific activity α:565.70728243222 Bq g^-1
1.528938601168 × 10^-8 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2-Magnetic dipole moment:μ(μ_N) = -0.8090(14)Charge radius:4.9892(35) femtometer fmYear of discovery:1933

Radioactive Decay

Samarium-147 is a pure alpha emitter - a nuclide that decays radioactively to neodym-147 by emitting only α-particles.< /p>

Over the past few decades, at least 14 reports have been published measuring the half-life of the nuclide ¹⁴⁷Sm - with values all in the order of magnitude between 1.05 and 1.17 · 10¹¹ years. The article by I. M. Villa et al. provides an overview of this and a recommended value, which has been adopted here. (2020, [1]).

Half-life T_½ = 1.0625(38) × 10¹¹ a respectively 5.05395936 × 10¹⁸ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁴³Nd	100 %	2.3113(5) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁴⁷Eu, ¹⁴⁷Pm, ¹⁵¹Gd.

Occurrence

Samarium-147 is an isotope that occurs naturally on Earth. The isotope content of the element is 15%.

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Samarium Isotopic mixture	150.36 u	100 %
Isotope ¹⁴⁴Sm	143.91201(2) u	3.08(4) %	stable	0+
Isotope ¹⁴⁸Sm	147.91483(2) u	11.25(9) %	7(3)×10¹⁵ a	0+
Isotope ¹⁴⁹Sm	148.91719(2) u	13.82(10) %	stable	7/2-
Isotope ¹⁵⁰Sm	149.91728(2) u	7.37(9) %	stable	0+
Isotope ¹⁵²Sm	151.91974(2) u	26.74(9) %	stable	0+
Isotope ¹⁵⁴Sm	153.92222(2) u	22.74(14) %	stable	0+
Isotope ¹⁴⁷Sm	146.91490(2) u	15.00(14) %	1.0625(38) × 10¹¹ a	7/2-
Isotope ¹⁴⁶Sm	145.913047(3) u	[trace]	9.20 (26) × 10⁷ a	0+

NMR data

Nuclear magnetic properties of the NMR active Nuclide ¹⁴⁷Sm

Isotope:¹⁴⁷Sm-NMRQuantity:15.00(14) %Spin:7/2-Nuclearmagnetic moment
μ/μ_N:-0.8090(14)Gyromagnetic ratio γ:1.1124 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = -0.23114285714286Quadrupole moment Q:- 0.259(26) barn (100 fm²)Resonance frequency:v₀ = 1.7748 at 1 TRelative Sensitivity:0.00152 (H₀ = const.)
0.8754 (v₀ = const.)
[related to ¹H = 1.000]

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 85) and isobaric (same nucleon number A = 147) with Samarium-147. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 85	Isobar A = 147
47	¹³²Ag
48	¹³³Cd
49	¹³⁴In
50	¹³⁵Sn
51	¹³⁶Sb
52	¹³⁷Te
53	¹³⁸I
54	¹³⁹Xe	¹⁴⁷Xe
55	¹⁴⁰Cs	¹⁴⁷Cs
56	¹⁴¹Ba	¹⁴⁷Ba
57	¹⁴²La	¹⁴⁷La
58	¹⁴³Ce	¹⁴⁷Ce
59	¹⁴⁴Pr	¹⁴⁷Pr
60	¹⁴⁵Nd	¹⁴⁷Nd
61	¹⁴⁶Pm	¹⁴⁷Pm
62	¹⁴⁷Sm	¹⁴⁷Sm
63	¹⁴⁸Eu	¹⁴⁷Eu
64	¹⁴⁹Gd	¹⁴⁷Gd
65	¹⁵⁰Tb	¹⁴⁷Tb
66	¹⁵¹Dy	¹⁴⁷Dy
67	¹⁵²Ho	¹⁴⁷Ho
68	¹⁵³Er	¹⁴⁷Er
69	¹⁵⁴Tm	¹⁴⁷Tm
70	¹⁵⁵Yb
71	¹⁵⁶Lu
72	¹⁵⁷Hf
73	¹⁵⁸Ta
74	¹⁵⁹W
75	¹⁶⁰Re
76	¹⁶¹Os

External data and identifiers

Adopted Levels, Gammas:NuDat 147Sm

Literature and References

[1] - I. M. Villa, N. E. Holden, A. Possolo, R. B. Ickert, D. B. Hibbert, P. R. Renne:
IUPAC-IUGS recommendation on the half-lives of ¹⁴⁷Sm and ¹⁴⁶Sm.
In: Geochimica et Cosmochimica Acta, 285, 70-77, (2020), DOI 10.1016/j.gca.2020.06.022.