Americium-241

Properties and data of the isotope ²⁴¹Am.

Content

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Americium-241 is the artificial radioisotope of the element Americium, whose atomic nucleus has 146 neutrons in addition to the element-specific 95 protons, resulting in a mass number of 241: ²⁴¹Am.

General data

Name of the isotope:Americium-241; Am-241Symbol:²⁴¹Am or 24195AmMass number A:241 (= number of nucleons)Atomic number Z:95 (= number of protons)Neutrons N:146Isotopic mass:241.0568273(12) u (atomic weight of Americium-241)Nuclide mass:241.0047194 u (calculated nuclear mass without electrons)Mass excess:52.93429 MeVMass defect:1.951628476 u (per nucleus)Nuclear binding energy:1817.93021562 MeV (per nucleus)
7.5432789 MeV (average binding energy per nucleon)Separation energy:S_N = 6.647(14) MeV (first neutron)
S_P = 4.47996(17) MeV (first proton)Cross section:σ(n.γ) = 628(22) barn (thermal neutron capture cross-section)
σ(n.f) = 3.15(10) b (gap cross-section)Half-life:432.6(6) aDecay constant λ:5.08079296727 × 10^-11 s^-1Specific activity α:126959547423.58 Bq g^-1
3.4313391195562 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Magnetic dipole moment:μ(μ_N) = + 1.58(1)Charge radius:5.8928(42) femtometer fmYear of discovery:1949

Radioactive Decay

Half-life T_½ = 432.6(6) a respectively 1.36425 × 10¹⁰ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²³⁷Np	ca. 100 %	5.63782(12) MeV	59.5409(1) keV 35.9(4) % 0.02138(22) MeV/Bq-s
SZ	^div	trace

Parent Nuclides

Direct parent isotopes are: ²⁴⁵Bk, ²⁴¹Cm, ²⁴¹Pu.

NMR data

Nuclear magnetic properties of the NMR active Nuclide ²⁴¹Am

Isotope:²⁴¹Am-NMRQuantity:Does not occur in nature!Spin:5/2-Nuclearmagnetic moment
μ/μ_N:+ 1.58(1)Gyromagnetic ratio γ:1.04 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 0.632Quadrupole moment Q:+4.34(5) barn (100 fm²)Line width parameter (factor):l = 60273.92 fm⁴

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^241mAm	2200(100) keV	1.2(3) μs

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 146) and isobaric (same nucleon number A = 241) with Americium-241. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 146	Isobar A = 241
87	²³³Fr
88	²³⁴Ra
89	²³⁵Ac
90	²³⁶Th
91	²³⁷Pa
92	²³⁸U	²⁴¹U
93	²³⁹Np	²⁴¹Np
94	²⁴⁰Pu	²⁴¹Pu
95	²⁴¹Am	²⁴¹Am
96	²⁴²Cm	²⁴¹Cm
97	²⁴³Bk	²⁴¹Bk
98	²⁴⁴Cf	²⁴¹Cf
99	²⁴⁵Es	²⁴¹Es
100	²⁴⁶Fm	²⁴¹Fm
101	²⁴⁷Md

External data and identifiers

CAS:14596-10-2InChI Key:LXQXZNRPTYVCNG-YPZZEJLDSA-NSMILES:[241Am]PubChem:ID 104726Adopted Levels, Gammas:NuDat 241Am

Literature and References

[1] - Shoji Nakamura et al.:
Thermal-Neutron Capture Cross Section and Resonance Integral of Americium-241.
In: Journal of Nuclear Science and Technology, (2007), DOI 10.1080/18811248.2007.9711399.