Erbium-149

Properties and data of the isotope ¹⁴⁹Er.

Content

General data

Name of the isotope:Erbium-149; Er-149Symbol:¹⁴⁹Er or 14968ErMass number A:149 (= number of nucleons)Atomic number Z:68 (= number of protons)Neutrons N:81Isotopic mass:148.94231(3) u (atomic weight of Erbium-149)Nuclide mass:148.9050099 u (calculated nuclear mass without electrons)Mass excess:-53.73789 MeVMass defect:1.291650372 u (per nucleus)Nuclear binding energy:1203.16457162 MeV (per nucleus)
8.07493001 MeV (average binding energy per nucleon)Separation energy:S_N = 10.33(3) MeV (first neutron)
S_P = 3.04(9) MeV (first proton)Half-life:4(2) sDecay constant λ:0.17328679513999 s^-1Specific activity α:7.051064118243 × 10⁺²⁰ Bq g^-1
19056930049.306 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2+)Year of discovery:1984

Radioactive Decay

Half-life T_½ = 4(2) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁴⁹Ho	93 %	7.90(3) MeV
EE, p	¹⁴⁸Dy	7 %

Parent Nuclides

Direct parent isotope is: ¹⁴⁹Tm.

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
^149m1Er	741.8(2) keV	8.9(2) s	(11/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 149) with Erbium-149. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 81	Isobar A = 149
45	¹²⁶Rh
46	¹²⁷Pd
47	¹²⁸Ag
48	¹²⁹Cd
49	¹³⁰In
50	¹³¹Sn
51	¹³²Sb
52	¹³³Te
53	¹³⁴I
54	¹³⁵Xe
55	¹³⁶Cs	¹⁴⁹Cs
56	¹³⁷Ba	¹⁴⁹Ba
57	¹³⁸La	¹⁴⁹La
58	¹³⁹Ce	¹⁴⁹Ce
59	¹⁴⁰Pr	¹⁴⁹Pr
60	¹⁴¹Nd	¹⁴⁹Nd
61	¹⁴²Pm	¹⁴⁹Pm
62	¹⁴³Sm	¹⁴⁹Sm
63	¹⁴⁴Eu	¹⁴⁹Eu
64	¹⁴⁵Gd	¹⁴⁹Gd
65	¹⁴⁶Tb	¹⁴⁹Tb
66	¹⁴⁷Dy	¹⁴⁹Dy
67	¹⁴⁸Ho	¹⁴⁹Ho
68	¹⁴⁹Er	¹⁴⁹Er
69	¹⁵⁰Tm	¹⁴⁹Tm
70	¹⁵¹Yb	¹⁴⁹Yb
71	¹⁵²Lu	¹⁴⁹Lu
72	¹⁵³Hf