Fluorine-19 is the only stable isotope of the chemical element fluorine. The atomic nucleus of the nuclide consists of the specific elements 9 protons and 10 neutrons; the sum of the nucleons gives the mass number 19.
19F is a NMR active nucleus and can therefore be measured using NMR spectroscopy for the detection and identification of fluorine-containing compounds. The corresponding analysis technique is fluorine-19 nuclear magnetic resonance spectroscopy (also fluorine NMR or 19F-NMR; see also below).
F-19 was first characterized as an independent isotope in 1920 based on its mass spectrum [1].
See also: List of individual Fluorine isotopes (and general data sources).
General data
Name of the isotope:Fluorine-19; F-19Symbol:19F or 199FMass number A:19 (= number of nucleons)Atomic number Z:9 (= number of protons)Neutrons N:10Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.1111111111111 (= neutron-proton ratio)Neutron excess (N-Z):1Isotopic mass:18.998403163(6) u (atomic weight of Fluorine-19)Nuclide mass:18.993466 u (calculated nuclear mass without electrons)Mass excess:-1.48744 MeVMass defect:0.158671285 u (per nucleus)Nuclear binding energy:147.80134995 MeV (per nucleus) 7.77901842 MeV (average binding energy per nucleon)Separation energy:SN = 10.4319(5) MeV (first neutron) SP = 7.9935998(10) MeV (first proton)Half-life:stableSpin and parity: (nuclear angular momentum)1/2+Isobaric spin: 1/2Magnetic dipole moment:μ(μN) = +2.628321(4)Charge radius:2.8976(25) femtometer fmMirror nucleus:Neon-19Year of discovery:1920
Isotope:19F-NMRQuantity:100 %Spin:1/2+Nuclearmagnetic moment μ/μN:+2.628321(4)Gyromagnetic ratio γ:25.18148 · 107 rad T-1 s-1 40.07757 MHz T-1Nuclear g-factor:gl = 5.256642Quadrupole moment Q:-0.0942(9) barn (100 fm2)Resonance frequency:v0 = 40.0776 MHz at 1 TRelative Sensitivity:[related to 1H = 1.000]: 0.83400 (H0 = const.) 0.9413 (v0 = const.) 0.834 (at natural abundance) relative receptivity as compared to 13C: 0.00490 (at natural abundance)Reference compound: (conditions)Purified trichlorofluoromethane (CFCl3).Frequency ratio:Ξ(19F) = 94.094011 % [based on the reference substance]
19F-NMR spectroscopy (fluorine-19 nuclear magnetic resonance spectroscopy) is a spectroscopic method for characterizing fluorinated organic and inorganic compounds, which is characterized by high sensitivity, sharp NMR signals and a large chemical shift range (about 800 ppm).
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 10) and isobaric (same nucleon number A = 19) with Fluorine-19. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
