Thulium-149

Properties and data of the isotope ¹⁴⁹Tm.

Contents

General data

Name of the isotope:Thulium-149; Tm-149Symbol:¹⁴⁹Tm or 14969TmMass number A:149 (= number of nucleons)Atomic number Z:69 (= number of protons)Neutrons N:80Isotopic mass:148.95289(21) u (atomic weight of Thulium-149)Nuclide mass:148.9150414 u (calculated nuclear mass without electrons)Mass excess:-43.88268 MeVMass defect:1.280230488 u (per nucleus)Nuclear binding energy:1192.52701819 MeV (per nucleus)
8.00353703 MeV (average binding energy per nucleon)Separation energy:S_N = 13.19(20) MeV (first neutron)Half-life:0.9(2) sDecay constant λ:0.77016353395549 s^-1Specific activity α:3.133806274774 × 10⁺²¹ Bq g^-1
84697466885.805 Ci g^-1Spin and parity:
(nuclear angular momentum)(11/2-)Year of discovery:1987

Radioactive Decay

Half-life T_½ = 0.9(2) s respectively 9 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁴⁹Er	ca. 99.8 %	9.86(20) MeV
EC, p	¹⁴⁸Ho	ca. 0.2 %

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 80) and isobaric (same nucleon number A = 149) with Thulium-149. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 80	Isobar A = 149
44	¹²⁴Ru
45	¹²⁵Rh
46	¹²⁶Pd
47	¹²⁷Ag
48	¹²⁸Cd
49	¹²⁹In
50	¹³⁰Sn
51	¹³¹Sb
52	¹³²Te
53	¹³³I
54	¹³⁴Xe
55	¹³⁵Cs	¹⁴⁹Cs
56	¹³⁶Ba	¹⁴⁹Ba
57	¹³⁷La	¹⁴⁹La
58	¹³⁸Ce	¹⁴⁹Ce
59	¹³⁹Pr	¹⁴⁹Pr
60	¹⁴⁰Nd	¹⁴⁹Nd
61	¹⁴¹Pm	¹⁴⁹Pm
62	¹⁴²Sm	¹⁴⁹Sm
63	¹⁴³Eu	¹⁴⁹Eu
64	¹⁴⁴Gd	¹⁴⁹Gd
65	¹⁴⁵Tb	¹⁴⁹Tb
66	¹⁴⁶Dy	¹⁴⁹Dy
67	¹⁴⁷Ho	¹⁴⁹Ho
68	¹⁴⁸Er	¹⁴⁹Er
69	¹⁴⁹Tm	¹⁴⁹Tm
70	¹⁵⁰Yb	¹⁴⁹Yb
71	¹⁵¹Lu	¹⁴⁹Lu