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Isotopes Of Fluorine
Fluorine (9F) has 19 known isotopes ranging from to and two isomers ( and ). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element. The longest-lived radioisotope is ; it has a half-life of . All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is , whose half-life is , corresponding to a resonance width of . List of isotopes , -id=Fluorine-13 , , style="text-align:right" , 9 , style="text-align:right" , 4 , # , , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 1/2+# , , -id=Fluorine-14 , , style="text-align:right" , 9 , style="text-align:right" , 5 , , [] , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 2− , , -id=Fluorine-15 , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Oxygen
There are three known stable isotopes of oxygen (8O): , , and . Radioactive isotopes ranging from to have also been characterized, all short-lived. The longest-lived radioisotope is with a half-life of , while the shortest-lived isotope is the unbound with a half-life of , though half-lives have not been measured for the unbound heavy isotopes and . List of isotopes , -id=Oxygen-11 , , style="text-align:right" , 8 , style="text-align:right" , 3 , , [] , proton emission, 2p , , (3/2−) , , , -id=Oxygen-12 , , style="text-align:right" , 8 , style="text-align:right" , 4 , , , 2p , , 0+ , , , - , rowspan=3, , rowspan=3 style="text-align:right" , 8 , rowspan=3 style="text-align:right" , 5 , rowspan=3, , rowspan=3, , β+ () , , rowspan=3, (3/2−) , rowspan=3, , rowspan=3, , - , β+p () , , - , β+p,α ( , - , Can be used in NMR studies of metabolic pathways. , style="text-align:right" , 8 , style="text-align:right ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine
Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extremely Reactivity (chemistry), reactive as it reacts with all other Periodic table, elements except for the light Noble gas, noble gases. It is highly toxicity, toxic. Among the elements, fluorine ranks Abundance of the chemical elements, 24th in cosmic abundance and 13th in crustal abundance. Fluorite, the primary mineral source of fluorine, which gave the element its name, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the Latin verb meaning gave the mineral its name. Proposed as an element in 1810, fluorine proved difficult and dangerous to separate from its compounds, and several early experimenters died or sustained injuries from their attempts. Only in 1886 did French chemist He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fludeoxyglucose
[]Fluorodeoxyglucose (International Nonproprietary Name, INN), or fluorodeoxyglucose F 18 (United States Adopted Name, USAN and United States Pharmacopeia, USP), also commonly called fluorodeoxyglucose and abbreviated []FDG, 2-[]FDG or FDG, is a radiopharmaceutical, specifically a radiotracer, used in the medical imaging modality positron emission tomography (PET). Chemically, it is 2-deoxy-2-[]fluoro-D-glucose, a glucose analog (chemistry), analog, with the positron-emitting radionuclide fluorine-18 substituted for the normal hydroxyl group at the C-2 position in the glucose molecule. The uptake of []FDG by tissues is a marker for the tissue Glucose uptake, uptake of glucose, which in turn is closely correlated with certain types of tissue metabolism. After []FDG is injected into a patient, a PET scanner can form two-dimensional or three-dimensional images of the distribution of []FDG within the body. Since its development in 1976, []FDG had a profound influence on r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Neon
Neon (10Ne) possesses three stable isotopes: , , and . In addition, 17 radioactive isotopes have been discovered, ranging from to , all short-lived. The longest-lived is with a half-life of . All others are under a minute, most under a second. The least stable is with a half-life of (). See isotopes of carbon for notes about the measurement. Light radioactive neon isotopes usually decay to fluorine or oxygen, while heavier ones decay to sodium. List of isotopes , -id=Neon-15 , , style="text-align:right" , 10 , style="text-align:right" , 5 , , [] , proton emission, 2p , , (3/2−) , , , -id=Neon-16 , , style="text-align:right" , 10 , style="text-align:right" , 6 , , > [ , -id=Neon-21 , , style="text-align:right" , 10 , style="text-align:right" , 11 , , colspan=3 align=center, Stable , 3/2+ , , ref name="Isotopic Composition of Elements" /> , -id=Neon-22 , , style="text-align:right" , 10 , style="text-align:right" , 12 , , c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomeric Transition
A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). "Metastable" describes nuclei whose excited states have half-lives of 10−9 seconds or longer, 100 to 1000 times longer than the half-lives of the excited nuclear states that decay with a "prompt" half life (ordinarily on the order of 10−12 seconds). Some references recommend seconds to distinguish the metastable half life from the normal "prompt" gamma-emission half-life. Occasionally the half-lives are far longer than this and can last minutes, hours, or years. For example, the nuclear isomer survives so long (at least years) that it has never been observed to decay spontaneously. The half-life of a nuclear isomer can even exceed that of the ground state of the same nuclide, as shown by as well as , , , , and multiple holmium isomers. Sometimes, the gamma decay from a metastable state is referred ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Isomer
A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). "Metastable" describes nuclei whose excited states have Half-life, half-lives of 10−9 seconds or longer, 100 to 1000 times longer than the half-lives of the excited nuclear states that decay with a "prompt" half life (ordinarily on the order of 10−12 seconds). Some references recommend seconds to distinguish the metastable half life from the normal "prompt" Induced gamma emission, gamma-emission half-life. Occasionally the half-lives are far longer than this and can last minutes, hours, or years. For example, the Isotopes of tantalum#Tantalum-180m, nuclear isomer survives so long (at least years) that it has never been observed to decay spontaneously. The half-life of a nuclear isomer can even exceed that of the ground state of the same nuclide, as shown by as well as isotopes of rhenium, , isotopes of iridium, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Activity
Specific activity (symbol ''a'') is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g). In the context of radioactivity, activity or total activity (symbol ''A'') is a physical quantity defined as the number of radioactive transformations per second that occur in a particular radionuclide. The unit of activity is the ''becquerel'' (symbol Bq), which is defined equivalent to reciprocal seconds (symbol s−1). The older, non-SI unit of activity is the ''curie'' (Ci), which is radioactive decays per second. Another unit of activity is the ''rutherford'', which is defined as radioactive decays per second. The specific activity should not be confused with level of exposure to ionizing radiation and thus the exposure or absorbed dose, which is the quantity important in assessing the effects of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine-20
Fluorine (9F) has 19 known isotopes ranging from to and two isomers ( and ). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element. The longest-lived radioisotope is ; it has a half-life of . All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is , whose half-life is , corresponding to a resonance width of . List of isotopes , -id=Fluorine-13 , , style="text-align:right" , 9 , style="text-align:right" , 4 , # , , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 1/2+# , , -id=Fluorine-14 , , style="text-align:right" , 9 , style="text-align:right" , 5 , , [] , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 2− , , -id=Fluorine-15 , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Lifetime
A quantity is subject to exponential decay if it decreases at a rate proportional to its current value. Symbolically, this process can be expressed by the following differential equation, where is the quantity and ( lambda) is a positive rate called the exponential decay constant, disintegration constant, rate constant, or transformation constant: :\frac = -\lambda N(t). The solution to this equation (see derivation below) is: :N(t) = N_0 e^, where is the quantity at time , is the initial quantity, that is, the quantity at time . Measuring rates of decay Mean lifetime If the decaying quantity, ''N''(''t''), is the number of discrete elements in a certain set, it is possible to compute the average length of time that an element remains in the set. This is called the mean lifetime (or simply the lifetime), where the exponential time constant, \tau, relates to the decay rate constant, λ, in the following way: :\tau = \frac. The mean lifetime can be looke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Activity
Specific activity (symbol ''a'') is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g). In the context of radioactivity, activity or total activity (symbol ''A'') is a physical quantity defined as the number of radioactive transformations per second that occur in a particular radionuclide. The unit of activity is the ''becquerel'' (symbol Bq), which is defined equivalent to reciprocal seconds (symbol s−1). The older, non-SI unit of activity is the ''curie'' (Ci), which is radioactive decays per second. Another unit of activity is the ''rutherford'', which is defined as radioactive decays per second. The specific activity should not be confused with level of exposure to ionizing radiation and thus the exposure or absorbed dose, which is the quantity important in assessing the effects of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine-19 NMR
Fluorine-19 nuclear magnetic resonance spectroscopy (fluorine NMR or 19F NMR) is an analytical technique used to detect and identify fluorine-containing compounds. 19F is an important nucleus for NMR spectroscopy because of its receptivity and large chemical shift dispersion, which is greater than that for proton nuclear magnetic resonance spectroscopy. Operational details 19F has a nuclear spin (I) of and a high gyromagnetic ratio. Consequently, this isotope is highly responsive to NMR measurements. Furthermore, 19F comprises 100% of naturally occurring fluorine. The only other highly sensitive spin NMR-active nuclei that are monoisotopic (or nearly so) are 1H and 31P. Indeed, the 19F nucleus is the third most receptive NMR nucleus, after the 3H nucleus and 1H nucleus. The 19F NMR chemical shifts span a range of about 800 ppm. For ''organo''fluorine compounds the range is narrower, being about −50 to −70 ppm (for CF3 groups) to −200 to −220 ppm ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
