Bismuth-209

Properties and data of the isotope ²⁰⁹Bi.

Contents

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Bismuth-209 is a quasi-stable isotope of the chemical element bismuth, which has 126 neutrons in its atomic nucleus in addition to the element-specific 83 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 209.

In 1924, bismuth-209 was identified by mass spectrometry. Metallic bismuth was used in the anode mixture of a mass spectrometer. The resulting spectrum showed only a single line at the expected position for mass 209, which also confirmed that natural bismuth contains only this one isotope [1].

Until 2003, bismuth-209 was considered the heaviest stable isotope. However, most heavy atomic nuclei are metastable with respect to alpha decay. In 2003, the alpha decay of bismuth-209 to thallium-205 was detected using a bismuth germanate detector cooled to 20 mK [2]. However, since the decay probability is extremely low and the low-energy alpha particles are undetectable with conventional measurement methods, the radioactivity of bismuth-209 is practically irrelevant; the isotope is quasi stable.

See also: List of individual Bismuth isotopes (and general data sources).

General data

Name of the isotope:Bismuth-209; Bi-209Symbol:²⁰⁹Bi or 20983BiMass number A:209 (= number of nucleons)Atomic number Z:83 (= number of protons)Neutrons N:126Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5180722891566 (= neutron-proton ratio)Neutron excess (N-Z):43Isotopic mass:208.9803986(15) u (atomic weight of Bismuth-209)Nuclide mass:208.9348717 u (calculated nuclear mass without electrons)Mass excess:-18.25859 MeVMass defect:1.760858472 u (per nucleus)Nuclear binding energy:1640.22910152 MeV (per nucleus)
7.84798613 MeV (average binding energy per nucleon)Separation energy:S_N = 7.4598(19) MeV (first neutron)
S_P = 3.7990(8) MeV (first proton)Half-life:2.01(8) × 10¹⁹ aDecay constant λ:1.092784968471 × 10^-27 s^-1Specific activity α:3.163896639307 × 10^-6 Bq g^-1
8.551071998128 × 10^-17 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Magnetic dipole moment:μ(μ_N) = + 4.1106(2)Charge radius:5.5211(906) femtometer fmYear of discovery:1924

Radioactive Decay

Half-life T_½ = 2.01(8) × 10¹⁹ a respectively 6.342942120892992 × 10²⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	Details	γ energy (intensity)
α	²⁰⁵Tl	100 %	3.1373(8) MeV	α: 2.877 MeV [1.2(3) %] α: 3.0770(22) MeV [98.8(3) %]	0.205 MeV [ ]

Parent Nuclides

Direct parent isotopes are: ²¹³At, ²⁰⁹Po, ²⁰⁹Pb.

Occurrence

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Bismuth Isotopic mixture	208.98040 u	100 %
Isotope ²⁰⁹Bi	208.9803986(15) u	100 %	2.01(8) × 10¹⁹ a	9/2-

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ²⁰⁹Bi

Isotope:²⁰⁹Bi-NMRQuantity:100 %Spin:9/2-Nuclearmagnetic moment
μ/μ_N:+ 4.1106(2)Gyromagnetic ratio γ:4.3752 · 10⁷ rad T^-1 s^-1
6.96335 MHz T^-1Nuclear g-factor:g_l = 0.91346666666667Quadrupole moment Q:-0.516(15) barn (100 fm²)Line width parameter (factor):l = 197.23 fm⁴Resonance frequency:v₀ = 6.9630 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.14433 (H₀ = const.)
5.3968 (v₀ = const.)
0.144 (at natural abundance)
relative receptivity as compared to ¹³C:
848 (at natural abundance)Reference compound:
(conditions)The calibration substance consists of a saturated solution of bismuth nitrate in concentrated nitric acid, which is diluted 1:1 with deuterium oxide (D₂O).Frequency ratio:Ξ(²⁰⁹Bi) = 16.069288 % [based on the reference substance]

209Bi-NMR spectroscopy utilizes the exclusively naturally occurring nucleus 209Bi (I = 9/2) with a large magnetic moment, but is strongly influenced by quadrupole interactions. These lead to very broad lines in most chemical environments, especially in solids, which significantly limits the resolution. Applications are therefore primarily in qualitative solid-state and materials characterization, while line broadening and rapid relaxation represent the central experimental challenges.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 209) with Bismuth-209. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 126	Isobar A = 209
76	²⁰²Os
77	²⁰³Ir
78	²⁰⁴Pt
79	²⁰⁵Au	²⁰⁹Au
80	²⁰⁶Hg	²⁰⁹Hg
81	²⁰⁷Tl	²⁰⁹Tl
82	²⁰⁸Pb	²⁰⁹Pb
83	²⁰⁹Bi	²⁰⁹Bi
84	²¹⁰Po	²⁰⁹Po
85	²¹¹At	²⁰⁹At
86	²¹²Rn	²⁰⁹Rn
87	²¹³Fr	²⁰⁹Fr
88	²¹⁴Ra	²⁰⁹Ra
89	²¹⁵Ac	²⁰⁹Ac
90	²¹⁶Th	²⁰⁹Th
91	²¹⁷Pa
92	²¹⁸U
93	²¹⁹Np

External data and identifiers

Adopted Levels, Gammas:NuDat 209Bi

Literature and References

[1] - F. W. Aston:
The Mass-spectra of Cadmium, Tellurium, and Bismuth.
In: Nature, 114, 717, (1924), DOI 10.1038/114717b0.

[2] - Pierre de Marcillac, Noël Coron, Gérard Dambier, Jacques Leblanc, Jean-Pierre Moalic:
Experimental detection of α-particles from the radioactive decay of natural bismuth.
In: Nature, (2003), DOI 10.1038/nature01541.

[3] - Hiyam Hamaed et al.:
Application of Solid-State ²⁰⁹Bi NMR to the Structural Characterization of Bismuth-Containing Materials.
In: Journal of the American Chemical Society, 131, 23, (2009), DOI 10.1021/ja901347k.

[4] - Bogdan Nowak:
Comment on the reference compound for chemical shift and Knight shift determination of ²⁰⁹Bi nuclei.
In: Solid State Nuclear Magnetic Resonance, 66-67, (2015), DOI 10.1016/j.ssnmr.2014.12.001.

[5] - J. W. Beeman, M. Biassoni, C. Brofferio, C. Bucci et al.:
First Measurement of the Partial Widths of ²⁰⁹Bi Decay to the Ground and to the First Excited States.
In: Physical Review Letters, (2012), DOI 10.1103/PhysRevLett.108.062501.