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Carbon-11

Properties and data of the isotope 11C.

Contents
General Data
Radioactive Decay
Formation
Isotones und Isobares
Literature

 

Carbon-11 isotope

Carbon-11 or 11C is a radioactive isotope of mass 11 of the element carbon, which has a half-life of about 20, 5 minutes decays to boron-11. The atomic nucleus of the nuclide is made up of 5 neutrons and the 6 element-specific protons.

C-11 is commonly used as a positron-emittingKohlenstoff-11 radioisotope for radioactive labeling of molecules in positron emission tomography (PET). Among the many molecules used in this context, the radioligands [11C]DASB and [11C]Cimbi-5 are commonly used. The majority of 11C-labeled radiopharmaceuticals for clinical PET studies are radioactively labeled with the isotope using the standard heteroatom methylation reaction [for method review see K. Dahl, 2017].

The discovery of carbon-11 was first reported in 1934 [1].

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

 

General data

Name of the isotope:Carbon-11; C-11Symbol:11C or 116CMass number A:11 (= number of nucleons)Atomic number Z:6 (= number of protons)Neutrons N:5Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):0.83333333333333 (= neutron-proton ratio)Neutron excess (N-Z):-1Isotopic mass:11.01143260(6) u (atomic weight of Carbon-11)Nuclide mass:11.0081411 u (calculated nuclear mass without electrons)Mass excess:10.6494 MeVMass defect:0.078842172000002 u (per nucleus)Nuclear binding energy:73.44101016 MeV (per nucleus)
6.67645547 MeV (average binding energy per nucleon)Separation energy:SN = 13.12059(9) MeV (first neutron)
SP = 8.69018(6) MeV (first proton)Half-life:20.364(14) minDecay constant λ:0.00056729782996132 s-1Specific activity α:3.105770401421 × 10+19 Bq g-1
839397405.78957 Ci g-1Spin and parity:
(nuclear angular momentum)3/2-Isobaric spin: 1/2Magnetic dipole moment:μ(μN) = - 0.964(1)Quadrupole moment Q:0.03327(24) barn (100 fm2)Nuclear g-factor:gl = -0.64266666666667Charge radius:2.498 femtometer fmMatter radius:2.296 femtometer fmMirror nucleus:Boron-11Year of discovery:1934

 

Radioactive Decay

Half-life T½ = 20.364(14) min (minutes) respectively 1.22184 × 103 seconds s.

Decay
mode		DaughterProbabilityDecay energyγ energy
(intensity)
EC, β+11B100 %1.98169(6) MeV

 

Formation

Nucleosynthesis occurs by proton bombardment of nitrogen-14 in a cyclotron [3]:

14N + p → 11C + 4He.

In the cosmos, the nuclide is created in particular through interstellar spallation of N and O.

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 5) and isobaric (same nucleon number A = 11) with Carbon-11. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

ZIsotone N = 5Isobar A = 11
16H
27He
38Li11Li
49Be11Be
510B11B
611C11C
712N11N
813O11O
914F
1015Ne

 

External data and identifiers

CAS:14333-33-6InChI Key:OKTJSMMVPCPJKN-BJUDXGSMSA-NSMILES:[11C]PubChem:ID 114789Adopted Levels, Gammas:NuDat 11C

 

Literature and References

[1] - H. R. Crane, C. C. Lauritsen:
Radioactivity from Carbon and Boron Oxide Bombarded with Deutons and the Conversion of Positrons into Radiation.
In: Physical Review, 45, 430, (1934), DOI 10.1103/PhysRev.45.430.2.

[2] - Kenneth Dahl, Christer Halldin, Magnus Schou:
New methodologies for the preparation of carbon-11 labeled radiopharmaceuticals.
In: Expert Review, (2017), DOI 10.1007/s40336-017-0223-1.

[3] - Carlotta Taddei, Victor W. Pike:
[11C]Carbon monoxide: advances in production and application to PET radiotracer development over the past 15 years.
In: EJNMMI Radiopharmacy and Chemistry, 4, 25, (2019), DOI 10.1186/s41181-019-0073-4.

 

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