Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. It was coined by a Scottish doctor and writer Margaret Todd in 1913 in a suggestion to chemist Frederick Soddy.
Introduction
Isotope
Isotope | Introduction
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Isotopes are any of the several different forms of an element each having different atomic mass (mass number). Isotope can also refer to:
Isotope (disambiguation) | Introduction
Isotope masses from: Isotopic compositions and standard atomic masses from: Half-life, spin, and isomer data selected from:
Isotopes of iron | References
The doses are stored frozen until needed.
Prochymal | Introduction
The remaining 20% of fission products, or 1% of unprocessed fuel, for which the longest-lived isotopes are Cs and Sr, require special custody for only 300 years. Therefore, the mass of material needing special custody is 1% of the mass of unprocessed used fuel.
Burnup | Waste
Isotope masses from: Isotopic compositions and standard atomic masses from: Half-life, spin, and isomer data selected from:
Isotopes of hassium | References
It is possible that researchers in the future will measure clumped isotope ratios against internationally distributed reference materials, similar to the current method of measuring the bulk isotope composition of unknown samples.
Reference materials for stable isotope analysis | Clumped isotopes
The atomic masses of naturally occurring isotopes of an element determine the atomic mass of the element. When the element contains "N" isotopes, the expression below is applied for the average atomic mass formula_1:
Isotope | Atomic mass of isotopes
The cooled gas retrieved from the bottom of the cold store is compressed which heats the gas to ambient temperature. The gas is then transferred to the bottom of the hot vessel to be reheated.
Thermal energy storage | Isentropic
Thus, even mass isotopes tend to accumulate, especially in a thermal reactor.
Plutonium-240 | Nuclear properties
Isotope masses from: Isotopic compositions and standard atomic masses from: Half-life, spin, and isomer data selected from the following sources.
Isotopes of lead | References
Isotopes were then explained as elements with the same number of protons, but different numbers of neutrons within the nucleus.
Atom | Discovery of the neutron
The Δ notation of clumped isotopes is an analogue to δ notation of traditional isotopes (e.g. "δ"C, "δ"O, "δ"N, δS and "δ"D). The notation of traditional isotopes are defined as: formula_1‰
Methane clumped isotopes | Δ notation
The number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number.
Isotope | Introduction
This article aggregates the δ and R values of common and non-traditional stable isotope reference materials. formula_1
Reference materials for stable isotope analysis | Introduction
There are certified values for most of the materials listed in Table 1, about half of the materials listed in Tables 2-7, and few of the materials in Table 8.
Reference materials for stable isotope analysis | Overview
Because it is radioactive, it is typically stored behind at least of lead. Contact with Al may result in radiological contamination necessitating special tools for transfer, use, and storage.
Aluminium-26 | Introduction
The new data matched the previous (fabricated) data.
Isotopes of hassium | As decay product
Although isotopes are more relevant to nuclear chemistry or stable isotope chemistry than to conventional chemistry, different isotopes may be indicated with a prefixed superscript in a chemical formula. For example, the phosphate ion containing radioactive phosphorus-32 is [PO]. Also a study involving stable isotope ratios might include the molecule OO. A left-hand subscript is sometimes used redundantly to indicate the atomic number. For example, O for dioxygen, and for the most abundant isotopic species of dioxygen. This is convenient when writing equations for nuclear reactions, in order to show the balance of charge more clearly.
Chemical formula | Isotopes
it will be conserved).
Conjugate variables | Introduction
The gas (mainly He, Xe and Kr) is held for about 2 days until almost all Xe-135 and other short lived isotopes have decayed. Most of the gas can then be recycled. After an additional hold up of several months, radioactivity is low enough to separate the gas at low temperatures into helium (for reuse), xenon (for sale) and krypton, which needs storage (e.g. in compressed form) for an extended time (several decades) to wait for the decay of Kr-85. For cleaning the salt mixture several methods of chemical separation were proposed. Compared to classical PUREX reprocessing, pyroprocessing can be more compact and produce less secondary waste.
Liquid fluoride thorium reactor | Details by element group
An isotope and/or nuclide is specified by the name of the particular element (this indicates the atomic number) followed by a hyphen and the mass number (e.g. helium-3, helium-4, carbon-12, carbon-14, uranium-235 and uranium-239). When a chemical symbol is used, e.g. "C" for carbon, standard notation (now known as "AZE notation" because "A" is the mass number, "Z" the atomic number, and E for element) is to indicate the mass number (number of nucleons) with a superscript at the upper left of the chemical symbol and to indicate the atomic number with a subscript at the lower left (e.g. , , , , , and ).
Isotope | Notation
These grains preserve an isotopic record of the nucleosynthesis in individual stars. He is measuring the isotopic compositions of these grains with a new technique, resonant ionization mass spectrometry, that was developed by his collaborators at Argonne National Laboratory.
Andrew M. Davis | Academic Research
All of the period 3 elements occur in nature and have at least one stable isotope.
Period 3 element | Introduction
The original concentration of cosmogenic isotope in the sample is then calculated using the measured isotopic ratio, the mass of the sample, and the mass of carrier added to the sample.
Environmental radioactivity | Methods of measurement for the long-lived isotopes
Its behavior is that of a hydrogen atom and not a noble helium atom.
Isotopes of hydrogen | Hydrogen-4.1
In a 1994 review Richard Sherwood wrote, "sister to the Cheshire, the Isotope is two feet longer and five Portsmouth numbers faster."
Isotope (catamaran) | Operational history
A second separate table is given for odd-atomic numbered elements, which tend to have far fewer stable and long-lived (primordial) unstable nuclides.
List of elements by stability of isotopes | Tables
An alternate stable form, if it exists, may appear at pressures of at least 50 GPa and temperatures of at least 1,500 K; it has been thought to have an orthorhombic or a double hcp structure. as of December 2011, recent and ongoing experiments are being conducted on high-pressure and Superdense carbon allotropes.
Allotropes of iron | Experimental high temperature and pressure
Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins.
Helium | Isotopes
An atom is big compared to a quark, but it is very small when compared to a body cell. Fast food may be healthier than preserved food, but unhealthy compared to organic produce.
Relative term | Introduction
Error was calculated as the square root of the sum of the squares of fractional reported errors.
Reference materials for stable isotope analysis | Heavy isotope systems
Clumped isotopes present a distinct set of challenges for isotopic reference materials. By convention the clumped isotope composition of CO liberated from CaCO (Δ) and CH (Δ/Δ/Δ) are reported relative to a stochastic distribution of isotopes. That is, the ratio of a given isotopologue of a molecule with multiple isotopic substitutions against a reference isotopologue is reported normalized to that same abundance ratio where all isotopes are distributed randomly. In practice the chosen reference frame is almost always the isotopologue with no isotopic substitutions. This isCO for carbon dioxide and CH for methane. Standard isotopic reference materials are still required in clumped isotope analysis for measuring the bulk δ values of a sample, which are used to calculate the expected stochastic distribution and subsequently to infer clumped isotope temperatures.
Reference materials for stable isotope analysis | Clumped isotopes
The quasi-equilibrium produces radioactive isobars Ti, Cr, Fe, and Ni, which (except Ti) are created in abundance but decay after the explosion and leave the most stable isotope of the corresponding element at the same atomic weight. The most abundant and extant isotopes of elements produced in this way are Ti, Cr, and Fe. These decays are accompanied by the emission of gamma-rays (radiation from the nucleus), whose spectroscopic lines can be used to identify the isotope created by the decay. The detection of these emission lines were an important early product of gamma-ray astronomy.
Nucleosynthesis | Explosive nucleosynthesis
Short-lived isotopes that are not generated or replenished by natural processes are not found in nature, so they are known as extinct radionuclides. Their former existence is inferred from a superabundance of their stable or nearly stable decay products.
Extinct radionuclide | Introduction
[[Category:Isotopes| ]] [[Category:Nuclear physics]]
Nuclide | External links
Many specimens in biobanks are cryopreserved. Other specimens are stored in other ways.
Biological specimen | Storage techniques
These stable even-proton odd-neutron nuclides tend to be uncommon by abundance in nature, generally because, to form and enter into primordial abundance, they must have escaped capturing neutrons to form yet other stable even-even isotopes, during both the s-process and r-process of neutron capture, during nucleosynthesis in stars. For this reason, only and are the most naturally abundant isotopes of their element.
Isotope | Even atomic number
For "synthetic" elements, the isotope depends on the means of synthesis, so the concept of natural isotope abundance has no meaning. Therefore, for synthetic elements the total nucleon count (protons plus neutrons) of the most stable isotope, i.e. the isotope with the longest half-life—is listed in brackets as the atomic mass.
Synthetic element | Properties
The shortest-lived known isotope is nitrogen-10, with a half-life of about 200 yoctoseconds.
Isotopes of nitrogen | Introduction
In 2006, "Sortir du nucléaire" also claims that it contains more than 100 kg of disseminated plutonium, 200 tonnes of uranium, chemicals and heavy metals.
Manche storage centre | Remarks
Isotopes are also used to study paleoclimate. This is the study of how climate was in the past, from hundreds of years ago to hundreds of thousands of years ago. The only records of these times that we have are buried in rocks, sediments, biological shells, stalagmites and stalactites, etc. The isotope ratios in these samples were affected by the temperature, salinity, circulation of the ocean, precipitation, etc. of the climate at the time, causing a measurable change from the standards for isotope measurements. This is how climate information is encoded in these geological formations. Some of the many isotopes useful for environmental science are discussed below.
Environmental isotopes | Paleoclimate
Such a weapon is not known to have ever been built, tested, or used.
Isotopes of arsenic | Introduction
The molecule in question is made up of a radioactive isotope of aluminium with 13 protons and 13 neutrons bound together with atoms of fluorine.
CK Vulpeculae | Properties
The fossils are compressions of original carapaces of the arthropods and the organic carbon of the plant fossils.
Douglas Lake Member | Preservation
Fe is observationally stable, but theoretically can decay to Cr, with a half-life of more than years via double electron capture (εε).
Isotopes of iron | Iron-54
Under certain conditions, carbon can be found in its atomic form. It is formed by passing large electric currents through carbon under very low pressures. It is extremely unstable, but it is an intermittent product used in the creation of carbenes. Diatomic carbon can also be found under certain conditions. It is often detected via spectroscopy in extraterrestrial bodies, including comets and certain stars.
Allotropes of carbon | Atomic and diatomic carbon
Nitrogen isotopes indicate the trophic level position of organisms (reflective of the time the tissue samples were taken). There is a larger enrichment component with δN because its retention is higher than that of N. This can be seen by analyzing the waste of organisms. Cattle urine has shown that there is a depletion of N relative to the diet. As organisms eat each other, the N isotopes are transferred to the predators. Thus, organisms higher in the trophic pyramid have accumulated higher levels of N ( and higher δN values) relative to their prey and others before them in the food web.
Isotope analysis | Nitrogen-15
Isotopes are distinguished by the atomic mass number (total protons and neutrons) for a particular isotope of an element, with this number combined with the pertinent element's symbol. IUPAC prefers that isotope symbols be written in superscript notation when practical, for example C and U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used. As a special case, the three naturally occurring isotopes of the element hydrogen are often specified as H for H (protium), D for H (deuterium), and T for H (tritium). This convention is easier to use in chemical equations, replacing the need to write out the mass number for each atom.
Chemical element | Isotope symbols
The time required to lose half of a population of a given nuclide through radioactive decays, the so-called half-life, is a measure of how stable an isotope is. Similar to the periodic table of elements for atoms, nuclides are usually visually represented on a table (the so-called Segré chart or chart of nuclides) where the proton number is represented on the y-axis while the x-axis represents the neutron number.
On-Line Isotope Mass Separator | Background
Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. It was coined by a Scottish doctor and writer Margaret Todd in 1913 in a suggestion to chemist Frederick Soddy.
Isotope | Introduction
Reprocessed uranium is also mainly U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232.
Uranium-238 | Introduction
For example, the formula for heavy water may be written DO instead of HO.
Chemical element | Isotope symbols
Such a weapon is not known to have ever been built, tested, or used.
Isotopes of zinc | Introduction
Instead, it transforms by beta-decay into Bk:
Berkelium | Preparation of isotopes
They are stored in History Institute of Kyrgyzstan Academy of Sciences.
Saul Abramzon | Introduction
The isotopes of erbium range in atomic weight from () to (). The primary decay mode before the most abundant stable isotope, , is electron capture, and the primary mode after is beta decay. The primary decay products before are element 67 (holmium) isotopes, and the primary products after are element 69 (thulium) isotopes.
Erbium | Isotopes
The abundance of Ni present in extraterrestrial material may bring further insight into the origin and early history of the Solar System.
Iron | Isotopes
Stable isotopes do not decay, and the heavy and light isotope masses affect how they partition within the environment. Any deviation from a random distribution of the light and heavy isotopes within the environment is called fractionation, and consistent fractionations as a result of a particular process or reaction are called "isotope effects."
Position-specific isotope analysis | Theory
The stored text could also be edited, using keys on a simple, six-key array. Basic editing functions included Insert, Delete, Skip (character, line), and so on.
Harold Koplow | Introduction
The mass of the isotope is determined through subsequent calculation.
Sector mass spectrometer | Bainbridge-Jordan
Similarly, ice cores on land are enriched in the heavier O relative to O during warmer climatic phases (interglacials) as more energy is available for the evaporation of the heavier O isotope. The oxygen isotope record preserved in the ice cores is therefore a "mirror" of the record contained in ocean sediments. Oxygen isotopes preserve a record of the effects of the Milankovitch cycles on climate change during the Quaternary, revealing an approximately 100,000-year cyclicity in the Earth's climate.
Isotope analysis | <a href="Paleoclimatology">Paleoclimatology</a>
This requires significant lithium to adversely affect the He/He ratio. All degassed helium is lost to space eventually, due to the average speed of helium exceeding the escape velocity for the Earth. Thus, it is assumed the helium content and ratios of Earth's atmosphere have remained essentially stable.
Isotope geochemistry | Helium-3
Allotropes of iron
Hexaferrum | See also
The many radioisotopes that are not found in nature have been characterized after being artificially made. Certain elements have no stable isotopes and are composed "only" of radioactive isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82.
Chemical element | Isotopes
The dimeric unit contains a triple bond and is analogous to N. It can also be generated as a transient intermediate in solution by thermolysis of organophosphorus precursor reagents. At still higher temperatures, P dissociates into atomic P.
Phosphorus | Allotropes
By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.
Isotopes of sodium | Introduction
Moscovium (Mc) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was Mc in 2004. There are four known radioisotopes from Mc to Mc. The longest-lived isotope is Mc with a half-life of 0.65 seconds.
Isotopes of moscovium | Introduction
Cosmogenic He/Ne confirm that He is retained be the samples taken. Cosmogenic isotopes are rare isotopes created when a high-energy cosmic ray interacts with the nucleus of an atom. These isotopes are produced within earth materials such as rocks or soil, in Earth's atmosphere, and in extraterrestrial items such as meteorites. By measuring cosmogenic isotopes, scientists are able to gain insight into a range of geological and astronomical processes. There are both radioactive and stable cosmogenic isotopes. This assumes ⁴He released by heating is due to magmatic component with a helium isotopic composition which seems to be a reasonable assumption for a low uranium olivine.
Potrillo volcanic field | Isotope geochemistry
The density of the nucleus is thus:
Nuclear density | Introduction
This would indicate the radiation level is reasonably safe. However, when not in use, it would be prudent to store these lenses as far as possible from normally inhabited areas; allowing the inverse square relationship to attenuate the radiation.
Isotopes of thorium | Low dispersion lenses
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Table of nuclides (segmented, narrow) | Isotopes for elements 45-59
Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. The accurate measurements of rely on proper procedures of analysis, sample preparation and storage.
Oxygen-18 | Introduction
For 80 of the chemical elements, at least one stable isotope exists. As a rule, there is only a handful of stable isotopes for each of these elements, the average being 3.2 stable isotopes per element. Twenty-six elements have only a single stable isotope, while the largest number of stable isotopes observed for any element is ten, for the element tin. Elements 43, 61, and all elements numbered 83 or higher have no stable isotopes.
Atom | Nuclear properties
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Table of nuclides (segmented, wide) | Isotopes for elements 0-29
The tables below provide cross-sections and excitation energies for fusion reactions producing flerovium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.
Isotopes of flerovium | Yields of isotopes
Plutonium occurs in a variety of allotropes, even at ambient pressure. These allotropes differ widely in crystal structure and density; the α and δ allotropes differ in density by more than 25% at constant pressure.
Allotropes of plutonium | Introduction
There is a near symmetrical distribution of the dose rate from top to bottom of the chamber. HFIR personnel are available to assist in the design of sample holders by the users to achieve the required accumulated doses and dose rates. Temperature of the samples from the required dose rate can be estimated.
High Flux Isotope Reactor | Radiation Dose Rates and Accumulated Doses
Copernicium (Cn) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was Cn in 1996. There are 6 known radioisotopes (with one more unconfirmed); the longest-lived isotope is Cn with a half-life of 29 seconds.
Isotopes of copernicium | Introduction
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Table of nuclides (segmented, narrow) | Isotopes for elements 0-14
Depending on the strength of cation-carbonate oxygen (ie, Mg-O, Ca-O) bonds- different carbonate minerals can form or preserve clumped isotopic signatures differently.
Magnesite | Isotopic Structure: Clumped Isotope
This field is termed stable isotope geochemistry.
Stable isotope ratio | Introduction
Total angular momentum is always conserved, see Noether's theorem.
Angular momentum operator | Introduction
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Table of nuclides (segmented, wide) | Isotopes for elements 30-59
Apart from the isotopes Y, Y, and Y, with half-lives of 58.51 days, 79.8 hours, and 64 hours, respectively, all the other isotopes have half-lives of less than a day and most of less than an hour.
Yttrium | Isotopes and nucleosynthesis
Clumped isotopes are heavy isotopes that are bonded to other heavy isotopes. The relative abundance of clumped isotopes (and multiply-substituted isotopologues) in molecules such as methane, nitrous oxide, and carbonate is an area of active investigation. The carbonate clumped-isotope thermometer, or "C–O order/disorder carbonate thermometer", is a new approach for paleoclimate reconstruction, based on the temperature dependence of the clumping of C and O into bonds within the carbonate mineral lattice. This approach has the advantage that the O ratio in water is not necessary (different from the δO approach), but for precise paleotemperature estimation, it also needs very large and uncontaminated samples, long analytical runs, and extensive replication.
Clumped isotopes | Introduction
Ultracold neutrons (UCN) are free neutrons which can be stored in traps made from certain materials. The storage is based on the reflection of UCN by such materials under any angle of incidence.
Ultracold neutrons | Introduction
The table below provides cross-sections and excitation energies for cold fusion reactions producing copernicium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.
Isotopes of copernicium | Cold fusion
Since the radius of Holmium is 233 pm, an atomic memory device could store one yottabyte in an area roughly the size of a nickel.
Yottabyte | Examples
the sum of the number of protons and neutrons in the nucleus. Each isotope of an element has different stability depending on their numbers of protons and neutrons. The word nuclide is used to refer to the isotopes with respect to their stability and nuclear energy state. Stable nuclides can be found in nature but unstable (i.e. radioactive) ones cannot because they spontaneously decay into more stable nuclides. Scientists use accelerators and nuclear reactors to produce and examine radioactive nuclides. The neutron-to-proton ratio has a strong impact on the properties of the isotope in question. Most notably, as this ratio strongly departs from unity the isotopes usually become ever increasingly short-lived.
On-Line Isotope Mass Separator | Background
This predicted abundance assumes a non-biased stochastic distribution of isotopes, natural materials tend to deviate from these stochastic values, the study of which forms the basis of clumped isotope geochemistry. When a heavier isotope substitutes for a lighter isotope (e.g., O for O), the chemical bond's vibration will be slower, lowering its zero-point energy. In other words, thermodynamic stability is related to the isotopic composition of the molecule.
Clumped isotopes | Background
A neutral atom has the same number of electrons as protons. Thus different isotopes of a given element all have the same number of electrons and share a similar electronic structure. Because the chemical behavior of an atom is largely determined by its electronic structure, different isotopes exhibit nearly identical chemical behavior. The main exception to this is the kinetic isotope effect: due to their larger masses, heavier isotopes tend to react somewhat more slowly than lighter isotopes of the same element. This is most pronounced by far for protium (), deuterium (), and tritium (), because deuterium has twice the mass of protium and tritium has three times the mass of protium.
Isotope | Chemical and molecular properties
Nitrogen gas (N) makes up 78% of the atmosphere and is extremely well mixed over short time-scales, resulting in a homogenous isotopic distribution ideal for use as a reference material. Atmospheric N is commonly called AIR when being used as an isotopic reference. In addition to atmospheric N there are multiple N isotopic reference materials.
Reference materials for stable isotope analysis | Nitrogen
This relationship has been applied to analyses of fossil teeth, in order to predict the body temperatures of a woolly mammoth and a sauropod dinosaur. The latest Δ temperature calibration for (bio)apatite of Löffler et al. 2019 covers a wide temperature range of 1 to 80 °C and was applied to a fossil Megalodon shark tooth for calculating seawater temperatures and δO values.
Clumped isotopes | Paleobiology
There are three known stable isotopes of oxygen (O): O, O, and O. Radioactive isotopes ranging from O to O have also been characterized, all short-lived. The longest-lived radioisotope is O with a half-life of 122.24 seconds, while the shortest-lived isotope is O with a half-life of 580(30)×10 seconds (the half-life of the unbound O is still unknown).
Isotopes of oxygen | Introduction
The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or , which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number ("Z") as a subscript to the left of the element symbol directly below the mass number: .
Mass number | Introduction
The equation governing the decay of a radioactive isotope is: where "N" is the number of atoms of the isotope in the original sample (at time "t" = 0, when the organism from which the sample was taken died), and "N" is the number of atoms left after time "t". "λ" is a constant that depends on the particular isotope; for a given isotope it is equal to the reciprocal of the mean-life – i.e. the average or expected time a given atom will survive before undergoing radioactive decay. The mean-life, denoted by "τ", of is 8,267 years, so the equation above can be rewritten as: The sample is assumed to have originally had the same / ratio as the ratio in the atmosphere, and since the size of the sample is known, the total number of atoms in the sample can be calculated, yielding "N", the number of atoms in the original sample.
Radiocarbon dating | Principles
The isotopic compositions of biomolecules preserved in the sedimentary record can be used as a proxy for paleoenvironment reconstructions. Since water is the primary hydrogen source for photoautotrophs, the hydrogen isotope composition of their biomass can be related to the composition of their growth water and thereby used to gain insight into some properties of ancient environments. Studying hydrogen isotopes can be very valuable, as hydrogen is more directly related to climate than other relevant stable isotope systems. However, hydrogen atoms bonded to oxygen, nitrogen, or sulfur atoms are exchangeable with environmental hydrogen, which makes this system less straightforward [ref to earlier H exchange section].
Hydrogen isotope biogeochemistry | Biomolecules
Extinct isotopes of superheavy elements are isotopes of elements whose half-lives were too short to have lasted through the formation of the solar system and, because they are not replenished by natural processes, can nowadays only be found as their daughters trapped within sediment and meteorite samples dating billions of years ago.
Extinct isotopes of superheavy elements | Introduction
The table below provides cross-sections and excitation energies for cold fusion reactions producing rutherfordium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.
Isotopes of rutherfordium | Cold fusion
Error was calculated as the square root of the sum of the squares of fractional reported errors, consistent with standard error propagation, but is not propagated for ratios reached through secondary calculation.
Reference materials for stable isotope analysis | Common reference materials