Lanthanum-139

Properties and data of the isotope ¹³⁹La.

Content

General data

Name of the isotope:Lanthanum-139; La-139Symbol:¹³⁹La or 13957LaMass number A:139 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:82Isotopic mass:138.90636(2) u (atomic weight of Lanthanum-139)Nuclide mass:138.8750931 u (calculated nuclear mass without electrons)Mass excess:-87.2251 MeVMass defect:1.250189936 u (per nucleus)Nuclear binding energy:1164.54442424 MeV (per nucleus)
8.37801744 MeV (average binding energy per nucleon)Separation energy:S_N = 8.7783(25) MeV (first neutron)
S_P = 6.2535(20) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μ_N) = +2.7791(2)Charge radius:4.8550(49) femtometer fmYear of discovery:1924

Parent Nuclides

Direct parent isotopes are: ¹³⁹Ce, ¹³⁹Ba.

Occurrence

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Lanthanum Isotopic mixture	138.90547 u	100 %
Isotope ¹³⁸La	137.907118(3) u	0.08881(71) %	1.02(1) × 10¹¹ a	5+
Isotope ¹³⁹La	138.90636(2) u	99.91119(71) %	stable	7/2+

NMR data

Nuclear magnetic properties of the NMR active Nuclide ¹³⁹La

Isotope:¹³⁹La-NMRQuantity:99.91119(71) %Spin:7/2+Nuclearmagnetic moment
μ/μ_N:+2.7791(2)Gyromagnetic ratio γ:3.801 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 0.79402857142857Quadrupole moment Q:+ 0.206(4) barn (100 fm²)Resonance frequency:v₀ = 6.0612 at 1 TRelative Sensitivity:0.06058 (H₀ = const.)
2.9895 (v₀ = const.)
[related to ¹H = 1.000]

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 82) and isobaric (same nucleon number A = 139) with Lanthanum-139. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 82	Isobar A = 139
45	¹²⁷Rh
46	¹²⁸Pd
47	¹²⁹Ag
48	¹³⁰Cd
49	¹³¹In
50	¹³²Sn	¹³⁹Sn
51	¹³³Sb	¹³⁹Sb
52	¹³⁴Te	¹³⁹Te
53	¹³⁵I	¹³⁹I
54	¹³⁶Xe	¹³⁹Xe
55	¹³⁷Cs	¹³⁹Cs
56	¹³⁸Ba	¹³⁹Ba
57	¹³⁹La	¹³⁹La
58	¹⁴⁰Ce	¹³⁹Ce
59	¹⁴¹Pr	¹³⁹Pr
60	¹⁴²Nd	¹³⁹Nd
61	¹⁴³Pm	¹³⁹Pm
62	¹⁴⁴Sm	¹³⁹Sm
63	¹⁴⁵Eu	¹³⁹Eu
64	¹⁴⁶Gd	¹³⁹Gd
65	¹⁴⁷Tb	¹³⁹Tb
66	¹⁴⁸Dy	¹³⁹Dy
67	¹⁴⁹Ho
68	¹⁵⁰Er
69	¹⁵¹Tm
70	¹⁵²Yb
71	¹⁵³Lu
72	¹⁵⁴Hf
73	¹⁵⁵Ta