Silicon-39

Properties and data of the isotope ³⁹Si.

Contents

Silicon-39 is a radioisotope of the chemical element silicon, which has 25 neutrons in its atomic nucleus in addition to the element-specific 14 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 39. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ³⁹Si is exclusively for academic purposes.

According to a report from 1979, the neutron-rich isotope Silicium-39 was discovered during the fragmentation of calcium-48 ions - accelerated to 212 MeV per nucleon - on a Be target [1].

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

General data

Name of the isotope:Silicon-39; Si-39Symbol:³⁹Si or 3914SiMass number A:39 (= number of nucleons)Atomic number Z:14 (= number of protons)Neutrons N:25Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.7857142857143 (= neutron-proton ratio)Neutron excess (N-Z):11Isotopic mass:39.00249(15) u (atomic weight of Silicon-39)Nuclide mass:38.99481 u (calculated nuclear mass without electrons)Mass excess:2.31942 MeVMass defect:0.323683348 u (per nucleus)Nuclear binding energy:301.50909656 MeV (per nucleus)
7.73100248 MeV (average binding energy per nucleon)Separation energy:S_N = 1.581(171) MeV (first neutron)
S_P = 21.438(202) MeV (first proton)Half-life:41.2(41) msDecay constant λ:16.823960693203 s^-1Specific activity α:2.597852849141 × 10⁺²³ Bq g^-1
7021223916597.6 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2-)Year of discovery:1979

Radioactive Decay

Half-life T_½ = 41.2(41) ms respectively 4.12 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	³⁹P	67 %	15.09(18) MeV
β^-, n	³⁸P	33 %	8.871(155) MeV
β^-, 2n ?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 25) and isobaric (same nucleon number A = 39) with Silicon-39. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 25	Isobar A = 39
11	³⁶Na	³⁹Na
12	³⁷Mg	³⁹Mg
13	³⁸Al	³⁹Al
14	³⁹Si	³⁹Si
15	⁴⁰P	³⁹P
16	⁴¹S	³⁹S
17	⁴²Cl	³⁹Cl
18	⁴³Ar	³⁹Ar
19	⁴⁴K	³⁹K
20	⁴⁵Ca	³⁹Ca
21	⁴⁶Sc	³⁹Sc
22	⁴⁷Ti	³⁹Ti
23	⁴⁸V
24	⁴⁹Cr
25	⁵⁰Mn
26	⁵¹Fe
27	⁵²Co
28	⁵³Ni
29	⁵⁴Cu
30	⁵⁵Zn

External data and identifiers

Adopted Levels, Gammas:NuDat 39Si

Literature and References

[1] - G. D. Westfall, T. J. M. Symons, D. E. Greiner et al.:
Production of Neutron-Rich Nuclides by Fragmentation of 212-MeV/amu ⁴⁸Ca.
In: Physical Review Letters,43, 1859, (1979), DOI 10.1103/PhysRevLett.43.1859.