Lanthanum-133

Properties and data of the isotope ¹³³La.

Content

Lanthanum-133 is a radioisotope of the chemical element lanthanum, which, in addition to the element-specific 57 protons, has 76 neutrons in the atomic nucleus, resulting in the mass number 133.

The very short-lived, only artificially producible, unstable and therefore radioactive nuclide is currently the focus of medical research: As a positron emitter, La-133 is suitable as a theranostic - for example as a macropa chelator or as a PET radionuclide.

The La nuclide can be generated by cyclotron-based proton irradiation of an enriched Ba-134 target: ¹³⁴ Ba(p,2n)^{133< /sup>La.}

General data

Name of the isotope:Lanthanum-133; La-133Symbol:¹³³La or 13357LaMass number A:133 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:76Isotopic mass:132.90822(3) u (atomic weight of Lanthanum-133)Nuclide mass:132.8769531 u (calculated nuclear mass without electrons)Mass excess:-85.49252 MeVMass defect:1.19634044 u (per nucleus)Nuclear binding energy:1114.38394182 MeV (per nucleus)
8.37882663 MeV (average binding energy per nucleon)Separation energy:S_N = 9.84(5) MeV (first neutron)
S_P = 4.348(28) MeV (first proton)Half-life:3.912(8) hDecay constant λ:4.921801725175 × 10^-5 s^-1Specific activity α:2.245438126794 × 10⁺¹⁷ Bq g^-1
6068751.6940392 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Year of discovery:1950

Radioactive Decay

Half-life T_½ = 3.912(8) h (hours) respectively 1.40832 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³³Ba	100 %	2.059(28) MeV

Parent Nuclides

Direct parent isotope is: ¹³³Ce.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 76) and isobaric (same nucleon number A = 133) with Lanthanum-133. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 76	Isobar A = 133
42	¹¹⁸Mo
43	¹¹⁹Tc
44	¹²⁰Ru
45	¹²¹Rh
46	¹²²Pd
47	¹²³Ag
48	¹²⁴Cd	¹³³Cd
49	¹²⁵In	¹³³In
50	¹²⁶Sn	¹³³Sn
51	¹²⁷Sb	¹³³Sb
52	¹²⁸Te	¹³³Te
53	¹²⁹I	¹³³I
54	¹³⁰Xe	¹³³Xe
55	¹³¹Cs	¹³³Cs
56	¹³²Ba	¹³³Ba
57	¹³³La	¹³³La
58	¹³⁴Ce	¹³³Ce
59	¹³⁵Pr	¹³³Pr
60	¹³⁶Nd	¹³³Nd
61	¹³⁷Pm	¹³³Pm
62	¹³⁸Sm	¹³³Sm
63	¹³⁹Eu	¹³³Eu
64	¹⁴⁰Gd
65	¹⁴¹Tb
66	¹⁴²Dy
67	¹⁴³Ho
68	¹⁴⁴Er
69	¹⁴⁵Tm