Francium-216m

Properties and data of the isotope ^216mFr.

Contents

General Data

Radioactive Decay

Isotones und Isobares

Literature

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

General data

Name of the isotope:Francium-216m; Fr-216mSymbol:^216mFr or 216m87FrMass number A:216 (= number of nucleons)Atomic number Z:87 (= number of protons)Neutrons N:129Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.4827586206897 (= neutron-proton ratio)Neutron excess (N-Z):42Excitation energy:219(6) keVIsotopic mass:216.003190(4) u (atomic weight of Francium-216m)Nuclide mass:215.9554694 u (calculated nuclear mass without electrons)Mass excess:2.97147 MeVMass defect:1.795361948 u (per nucleus)Nuclear binding energy:1672.36888239 MeV (per nucleus)
7.74244853 MeV (average binding energy per nucleon)Half-life:850(30) nsDecay constant λ:815467.27124699 s^-1Specific activity α:2.273545728758 × 10⁺²⁷ Bq g^-1
6.14471818583 × 10⁺¹⁶ Ci g^-1Spin and parity:
(nuclear angular momentum)(9-)Year of discovery:2007

Radioactive Decay

Half-life T_½ = 850(30) ns respectively 8.5 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	^212m1At	100 %

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
²¹⁶Fr		0.70(2) μs	(1-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 216) with Francium-216m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 129	Isobar A = 216
78	²⁰⁷Pt
79	²⁰⁸Au
80	²⁰⁹Hg	²¹⁶Hg
81	²¹⁰Tl	²¹⁶Tl
82	²¹¹Pb	²¹⁶Pb
83	²¹²Bi	²¹⁶Bi
84	²¹³Po	²¹⁶Po
85	²¹⁴At	²¹⁶At
86	²¹⁵Rn	²¹⁶Rn
87	²¹⁶Fr	²¹⁶Fr
88	²¹⁷Ra	²¹⁶Ra
89	²¹⁸Ac	²¹⁶Ac
90	²¹⁹Th	²¹⁶Th
91	²²⁰Pa	²¹⁶Pa
92	²²¹U	²¹⁶U
93	²²²Np

Literature and References

[1] - J. Kurcewicz, W. Czarnacki, M. Karny et al.:
Identification of an α-decaying (9-) isomer in ²¹⁶Fr.
In: Physical Review C, 76, 054320, (2007), DOI 10.1103/PhysRevC.76.054320.