Silver-129m

Properties and data of the isotope ¹²⁹Ag.

Content

General data

Name of the isotope:Silver-129m; Ag-129mSymbol:¹²⁹Ag or 12947AgMass number A:129 (= number of nucleons)Atomic number Z:47 (= number of protons)Neutrons N:82Isotopic mass:128.94420(43) u (atomic weight of Silver-129m)
Excitation energy: +x keVNuclide mass:128.9184181 u (calculated nuclear mass without electrons)Mass excess:-51.97737 MeVMass defect:1.134099616 u (per nucleus)Nuclear binding energy:1056.40698771 MeV (per nucleus)
8.18920146 MeV (average binding energy per nucleon)Half-life:160 msDecay constant λ:4.3321698784997 s^-1Specific activity α:2.038198221679 × 10⁺²² Bq g^-1
550864384237.76 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2-)

Radioactive Decay

Half-life T_½ = 160 ms respectively 1.60 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹²⁹Cd	> 0 %
β^-, n	¹²⁸Cd	?

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
¹²⁹Ag		46 ms	(9/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 82) and isobaric (same nucleon number A = 129) with Silver-129m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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