Chlorine-39

Properties and data of the isotope ³⁹Cl.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Chlorine-39 is a radioisotope of the chemical element chlorine, which, in addition to the element-specific 17 protons, has 22 neutrons in the atomic nucleus, resulting in the mass number 39. The very short-lived, unstable and therefore radioactive nuclide has no practical significance from a technical point of view.

³⁹Cl is one of the cosmogenic nuclides that are continuously formed in the atmosphere by solar and cosmic radiation: The chlorine isotope is created by the interaction of slow negative muons μ^- of cosmic rays with Argon-40 in the lower air layers. The trace radioisotope chlorine-39, which decays quickly into the stable isotope Ar-39, can be detected in small quantities in rainwater samples [2].

General data

Name of the isotope:Chlorine-39; Cl-39Symbol:³⁹Cl or 3917ClMass number A:39 (= number of nucleons)Atomic number Z:17 (= number of protons)Neutrons N:22Isotopic mass:38.9680082(19) u (atomic weight of Chlorine-39)Nuclide mass:38.9586825 u (calculated nuclear mass without electrons)Mass excess:-29.80017 MeVMass defect:0.355645496 u (per nucleus)Nuclear binding energy:331.28164565 MeV (per nucleus)
8.49440117 MeV (average binding energy per nucleon)Separation energy:S_N = 8.0734(17) MeV (first neutron)
S_P = 10.228(7) MeV (first proton)Half-life:56.2(6) minDecay constant λ:0.00020555966208777 s^-1Specific activity α:3.257655895298 × 10⁺¹⁸ Bq g^-1
88044753.926992 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Mirror nucleus:Titanium-39Year of discovery:1949

Radioactive Decay

Half-life T_½ = 56.2(6) min (minutes) respectively 3.372 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	³⁹Ar	100 %	3.44197 MeV

Parent Nuclides

Direct parent isotope is: ³⁹S.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 22) and isobaric (same nucleon number A = 39) with Chlorine-39. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 22	Isobar A = 39
9	³¹F
10	³²Ne
11	³³Na	³⁹Na
12	³⁴Mg	³⁹Mg
13	³⁵Al	³⁹Al
14	³⁶Si	³⁹Si
15	³⁷P	³⁹P
16	³⁸S	³⁹S
17	³⁹Cl	³⁹Cl
18	⁴⁰Ar	³⁹Ar
19	⁴¹K	³⁹K
20	⁴²Ca	³⁹Ca
21	⁴³Sc	³⁹Sc
22	⁴⁴Ti	³⁹Ti
23	⁴⁵V
24	⁴⁶Cr
25	⁴⁷Mn
26	⁴⁸Fe
27	⁴⁹Co
28	⁵⁰Ni

External data and identifiers

Adopted Levels, Gammas:NuDat 39Cl

Literature and References

[1] - R. N. H. Haslam, L. Katz, H. E. Johns, H. J. Moody:
Confirmation of ³⁹Cl Activity.
In: Physical Review, 76, 704, (1949), DOI 10.1103/PhysRev.76.704.

[2] - C. Papastefanou:
Chlorine-39 in rainfall at a temperate latitude (40°N).
In: Journal of Environmental Radioactivity, (2007), DOI 10.1016/j.jenvrad.2006.11.005.