Xenon-129

Properties and data of the isotope ¹²⁹Xe.

Content

General data

Name of the isotope:Xenon-129; Xe-129Symbol:¹²⁹Xe or 12954XeMass number A:129 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:75Isotopic mass:128.90478086(4) u (atomic weight of Xenon-129)Nuclide mass:128.8751595 u (calculated nuclear mass without electrons)Mass excess:-88.69606 MeVMass defect:1.167639568 u (per nucleus)Nuclear binding energy:1087.64925175 MeV (per nucleus)
8.43138955 MeV (average binding energy per nucleon)Separation energy:S_N = 6.9071(11) MeV (first neutron)
S_P = 8.246(4) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = -0.777961(16)Charge radius:4.7775(50) femtometer fmYear of discovery:1920

Parent Nuclides

Direct parent isotopes are: ¹²⁹Cs, ¹²⁹I.

Occurrence

Comparison of the natural Xenon isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Xenon Isotopic mixture	131.293 u	100 %
Isotope ¹²⁴Xe	123.90589(2) u	0.095(5) %	> 1.8 × 10²² a	0+
Isotope ¹²⁶Xe	125.90430(3) u	0.089(3) %	stable	0+
Isotope ¹²⁸Xe	127.903531(7) u	1.910(13) %	stable	0+
Isotope ¹²⁹Xe	128.90478086(4) u	26.401(138) %	stable	1/2+
Isotope ¹³⁰Xe	129.9035094(1) u	4.071(22) %	stable	0+
Isotope ¹³¹Xe	130.905084(2) u	21.232(51) %	stable	3/2+
Isotope ¹³²Xe	131.90415509(4) u	26.909(55) %	stable	0+
Isotope ¹³⁴Xe	133.905393033(10) u	10.436(35) %	5.8 × 10²² a	0+
Isotope ¹³⁶Xe	135.90721448(7) u	8.857(72) %	2.165(61) × 10²¹ a	0+

NMR data

Nuclear magnetic properties of the NMR active Nuclide ¹²⁹Xe

Isotope:¹²⁹Xe-NMRQuantity:26.401(138) %Spin:1/2+Nuclearmagnetic moment
μ/μ_N:-0.777961(16)Gyromagnetic ratio γ:7.4521 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = -1.555922Resonance frequency:v₀ = 11.8604 at 1 TRelative Sensitivity:0.02162 (H₀ = const.)
0.2786 (v₀ = const.)
[related to ¹H = 1.000]

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
^129mXe	236.14(3) keV	8.88(2) d	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 75) and isobaric (same nucleon number A = 129) with Xenon-129. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 75	Isobar A = 129
42	¹¹⁷Mo
43	¹¹⁸Tc
44	¹¹⁹Ru
45	¹²⁰Rh
46	¹²¹Pd	¹²⁹Pd
47	¹²²Ag	¹²⁹Ag
48	¹²³Cd	¹²⁹Cd
49	¹²⁴In	¹²⁹In
50	¹²⁵Sn	¹²⁹Sn
51	¹²⁶Sb	¹²⁹Sb
52	¹²⁷Te	¹²⁹Te
53	¹²⁸I	¹²⁹I
54	¹²⁹Xe	¹²⁹Xe
55	¹³⁰Cs	¹²⁹Cs
56	¹³¹Ba	¹²⁹Ba
57	¹³²La	¹²⁹La
58	¹³³Ce	¹²⁹Ce
59	¹³⁴Pr	¹²⁹Pr
60	¹³⁵Nd	¹²⁹Nd
61	¹³⁶Pm	¹²⁹Pm
62	¹³⁷Sm	¹²⁹Sm
63	¹³⁸Eu
64	¹³⁹Gd
65	¹⁴⁰Tb
66	¹⁴¹Dy
67	¹⁴²Ho
68	¹⁴³Er
69	¹⁴⁴Tm