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Electron affinity || -53 kJ/mol
'Technetium' (
IPA: ) is the lightest
chemical element with no
stable isotope. It has
atomic number 43 and is given the symbol 'Tc'. The chemical properties of this silvery grey, crystalline
transition metal are intermediate between
rhenium and
manganese. Its short-lived gamma-emitting
nuclear isomer 99mTc (
technetium-99m) is used in
nuclear medicine for a wide variety of diagnostic tests.
99Tc is used as a
gamma ray-free source of
beta particles. The
pertechnetate ion (TcO
4-) could find use as an anodic
corrosion inhibitor for
steel.
Before the element was discovered, many of the properties of element 43
were predicted by
Dmitri Mendeleev. Mendeleev noted a gap in his
periodic table and called the element ''ekamanganese''. In 1937 its isotope
97Tc became the first predominantly artificial element to be produced, hence its name (from the
Greek ''τεχνητός'', meaning "artificial"). Most technetium produced on Earth is a by-product of
fission of
uranium-235 in
nuclear reactors and is extracted from
nuclear fuel rods. No isotope of technetium has a
half-life longer than 4.2 million years (
98Tc), so its detection in
red giants in 1952 helped bolster the theory that stars can produce heavier elements. Note that on Earth, technetium occurs in trace but measurable quantities as a product of
spontaneous fission in uranium ore or by
neutron capture in
molybdenum ores.
Characteristics
Technetium is a silvery-grey radioactive
metal with an appearance similar to
platinum. However, it is commonly obtained as a grey powder. Its position in the periodic table is between
rhenium and
manganese and as predicted by the
periodic law its properties are intermediate between those two elements. This element, like
promethium, is unusual among the lighter elements in that it has no stable
isotopes. Only these two elements have no stable isotopes, but are followed by elements which do.
Technetium is therefore extremely rare on
Earth. Technetium plays no natural biological role and is not normally found in the
human body.
The metal form of technetium slowly
tarnishes in moist air. Its
oxides are Tc
O2 and Tc
2O
7. Under oxidizing conditions technetium (VII) will exist as the
pertechnetate ion, TcO
4-.
[1] Common
oxidation states of technetium include 0, +2, +4, +5, +6 and +7.
[2] When in powder form technetium will burn in
oxygen.
[3] It dissolves in
aqua regia,
nitric acid, and concentrated
sulfuric acid, but it is not soluble in
hydrochloric acid. It has characteristic
spectral lines at 363
nm, 403 nm, 410 nm, 426 nm, 430 nm, and 485 nm.
[4]
The metal form is slightly
paramagnetic, meaning its
magnetic dipoles align with external
magnetic fields even though technetium is not normally magnetic.
[5] The
crystal structure of the metal is hexagonal close-packed. Pure metallic single-crystal technetium becomes a type II
superconductor at 7.46
K; irregular crystals and trace impurities raise this temperature to 11.2 K for 99.9% pure technetium powder.
[6] Below this temperature technetium has a very high
magnetic penetration depth, the largest among the elements apart from
niobium.
[7]
Technetium is produced in quantity by nuclear fission, and spreads more readily than many radionuclides. In spite of the importance of understanding its toxicity in animals and humans, experimental evidence is scant. It appears to have low chemical toxicity. Its radiological toxicity (per unit of mass) is a function of compound, type of radiation for the isotope in question, and the isotope half-life.
Technetium-99m is particularly attractive for medical applications, as the radiation from this isotope is a gamma ray with the same wavelength as X-rays used for common medical diagnostic X-ray applications, giving it adequate penetration while causing minimal damage for a gamma photon. This, plus the very short half-life of this metastable
nuclear isomer, followed by the relatively long half-life of the daughter isotope Tc-99 which allows it to be eliminated from the body before it decays, make for a relatively low dose of administered radiation in biologically dose-equivalent amounts (
sieverts) for a typical Tc-99m based nuclear scan (see more on this subject below).
All isotopes of technetium must be handled carefully. The most common isotope, technetium-99, is a weak beta emitter; such radiation is stopped by the walls of laboratory glassware. Soft
X-rays are emitted when the beta particles are stopped, but as long as the body is kept more than 30 cm away these should pose no problem. The primary hazard when working with technetium is inhalation of dust; such
radioactive contamination in the lungs can pose a significant cancer risk. For most work, careful handling in a
fume hood is sufficient; a
glove box is not needed.
Applications
Nuclear medicine
99mTc ("m" indicates that this is a
metastable nuclear isomer) is used in radioactive isotope
medical tests, for example as a
radioactive tracer that medical equipment can detect in the body.
[8] It is well suited to the role because it emits readily detectable 140
keV gamma rays, and its half-life is 6.01 hours (meaning that about fifteen sixteenths of it decays to
99Tc in 24 hours).
[9] Klaus Schwochau's book ''Technetium'' lists 31
radiopharmaceuticals based on
99mTc for imaging and functional studies of the
brain,
myocardium,
thyroid,
lungs,
liver,
gallbladder,
kidneys,
skeleton,
blood and
tumors.
Immunoscintigraphy incorporates
99mTc into a
monoclonal antibody, an
immune system protein capable of binding to
cancer cells. A few hours after injection, medical equipment is used to detect the gamma rays emitted by the
99mTc; higher concentrations indicate where the tumor is. This technique is particularly useful for detecting hard-to-find cancers, such as those affecting the
intestine. These modified antibodies are sold by the German company
Hoechst under the name "
Scintium".
[10]
When
99mTc is combined with a
tin compound it binds to
red blood cells and can therefore be used to map
circulatory system disorders. It is commonly used to detect gastrointestinal bleeding sites. A
pyrophosphate ion with
99mTc adheres to
calcium deposits in damaged
heart muscle, making it useful to gauge damage after a
heart attack.
[11] The
sulfur colloid of
99mTc is scavenged by the
spleen, making it possible to image the structure of the spleen.
[12]
Radiation exposure due to diagnostic treatment involving Tc-99m can be kept low. Because
99mTc has a short half-life and high energy gamma (allowing small amounts to be easily detected), its quick decay into the far-less radioactive
99Tc results in relatively less total radiation dose to the patient, per unit of initial activity after administration. In the form administered in these medical tests (usually pertechnetate) both isotopes are quickly eliminated from the body, generally within a few days.
Technetium for nuclear medicine purposes is usually extracted from
technetium-99m generators.
95mTc, with a half-life of 61 days, is used as a
radioactive tracer to study the movement of technetium in the environment and in plant and animal systems.
Industrial
Technetium-99 decays almost entirely by
beta decay, emitting beta particles with very consistent low energies and no accompanying
gamma rays. Moreover, its very long half-life means that this emission decreases very slowly with time. It can also be extracted to a high chemical and isotopic purity from radioactive waste. For these reasons, it is a
NIST standard beta emitter, used for equipment calibration.
Technetium-99 has also been proposed for use in optoelectric
nuclear batteries.
99Tc's beta decay electrons would stimulate an
excimer mixture, and the light would power a
photocell. The battery would consist of an excimer mixture of
argon/
xenon in a pressure vessel with an internal mirrored surface, finely divided
99Tc, and an intermittent
ultrasonic stirrer, illuminating a photocell with a bandgap tuned for the excimer. If the pressure-vessel is
carbon fiber/
epoxy, the theoretical weight to power ratio has been claimed to be comparable to an air-breathing engine with fuel tanks.
Chemical
Like
rhenium and
palladium, technetium can serve as a catalyst. For certain reactions, for example the
dehydrogenation of
isopropyl alcohol, it is a far more effective catalyst than either rhenium or palladium. Of course, its radioactivity is a major problem in finding safe applications.
Under certain circumstances, a small concentration (5×10
−5 mol/
L) of the pertechnetate ion in water can protect iron and carbon steels from corrosion. For this reason, pertechnetate could find use as an anodic
corrosion inhibitor for
steel, although technetium's radioactivity poses problems for strictly chemical uses such as these. While (for example) CrO
42− can also inhibit corrosion, it requires a concentration ten times as high. In one experiment, a test specimen was kept in an aqueous solution of pertechnetate for 20 years and was still uncorroded. The mechanism by which pertechnetate prevents corrosion is not well-understood, but seems to involve the reversible formation of a thin surface layer. One theory holds that the pertechnetate reacts with the steel surface to form a layer of technetium
dioxide which prevents further corrosion; the same effect explains how iron powder can be used to remove pertechnetate from water. (
Activated carbon can also be used for the same effect.) The effect disappears rapidly if the concentration of pertechnetate falls below the minimum concentration or if too high a concentration of other ions is added.
As noted, the radioactive nature of technetium (3 M
Bq per liter at the concentrations required) makes this corrosion protection impractical in almost all situations. Nevertheless, corrosion protection by pertechnetate ions was proposed (but never adopted) for use in
boiling water reactors.
During the late 1970s, technetium was successfully electroplated onto various substrates by Lichtenberger at the Univ. of Va. as part of a study to investigate anti-biofouling of various marine instruments by utilizing its weak beta emission. Follow up work was thwarted due to its lack of stability in sea water
History
Search for element 43
For a number of years there was a gap in the periodic table between
molybdenum (element 42) and
ruthenium (element 44). Many early researchers were eager to be the first to discover and name the missing element; its location in the table suggested that it should be easier to find than other undiscovered elements. It was first thought to have been found in
platinum ores in 1828. It was given the name ''
polinium'' but it turned out to be impure
iridium. Then in 1846 the element ''ilmenium'' was claimed to have been discovered but was determined to be impure
niobium. This mistake was repeated in 1847 with the "discovery" of ''pelopium''.
[13] Dmitri Mendeleev predicted that this missing element, as part of other predictions, would be chemically similar to
manganese and gave it the name ekamanganese.
In 1877, the Russian chemist
Serge Kern reported discovering the missing element in
platinum ore. Kern named what he thought was the new element ''davyum,'' after the noted English chemist Sir
Humphry Davy, but it was determined to be a mixture of iridium, rhodium and
iron. Another candidate, ''lucium,'' followed in 1896 but it was determined to be
yttrium. Then in 1908 the Japanese chemist
Masataka Ogawa found evidence in the mineral
thorianite which he thought indicated the presence of element 43. Ogawa named the element 'nipponium', after
Japan (which is ''Nippon'' in Japanese). In 2004 H. K YOSHIHARA utilized "a record of X-ray spectrum of Ogawa's nipponium sample from thorianite [which] was contained in a photographic plate preserved by his family. The spectrum was read and indicated the absence of the element 43 and the presence of the ''element 75'' (rhenium)."
[14]
German chemists
Walter Noddack,
Otto Berg and
Ida Tacke (later Mrs. Noddack) reported the discovery of ''element 75'' and element 43 in 1925 and named element 43 'masurium' (after
Masuria in eastern
Prussia, now in
Poland, the region where Walter Noddack's family originated).
The group bombarded
columbite with a beam of
electrons and deduced element 43 was present by examining
X-ray diffraction
spectrograms. The
wavelength of the X-rays produced is related to the atomic number by a formula derived by
Henry Moseley in 1913. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. Contemporary experimenters could not replicate the discovery, and in fact it was dismissed as an error for many years.
[15][16]
In 1998
John T. Armstrong of the
National Institute of Standards and Technology ran "computer simulations" of the 1925 experiments and obtained results very close to those reported by the Noddack team which he claimed was further supported by work published by
David Curtis of the
Los Alamos National Laboratory measuring the (tiny) natural occurrence of technetium.
However, the Noddack's experimental results have never been reproduced, and they were unable to isolate any element 43. Debate still exists as to whether the 1925 team actually did discover element 43, but it is extremely unlikely that even if this view were to be widely accepted that their proposed name would be adopted at this late date.
Official discovery and later history
Discovery of element 43 was finally confirmed in a 1937 experiment at the
University of Palermo in Sicily conducted by
Carlo Perrier and
Emilio Segrè. In the summer of 1936 Segrè and his wife visited the United States, first New York at
Columbia University, where he had spent time the previous summer, and then
Berkeley at
Ernest O. Lawrence's
Radiation Laboratory. He persuaded
cyclotron inventor Lawrence to let him take back some discarded cyclotron parts that had become radioactive. In early 1937 Lawrence mailed him a molybdenum foil that had been part of the deflector in the cyclotron. Segrè enlisted his experienced chemist colleague Perrier to attempt to prove through comparative chemistry that the molybdenum activity was indeed Z = 43, an element not existent in nature because of its instability against nuclear decay. With considerable difficulty they finally succeeded in isolating three distinct decay periods (90, 80, and 50 days) that eventually turned out to be two isotopes,
95Tc and
97Tc, of technetium, the name given later by Perrier and Segrè to the first man-made element.
[18] University of Palermo officials wanted them to name their discovery ''panormium'', after the
Latin name for
Palermo, ''Panormus''. The researchers instead named element 43 after the
Greek word ''τεχνητός'', meaning "artificial", since it was the first element to be artificially produced.
Segrè returned to Berkeley and immediately sought out
Glenn T. Seaborg. They isolated the technetium-99m isotope which is now used in some 10,000,000 medical diagnostic procedures annually.
[19]
In 1952 astronomer
Paul W. Merrill in
California detected the
spectral signature of technetium (in particular, light at 403.1 nm, 423.8 nm, 426.8 nm, and 429.7 nm) in light from
S-type red giants.
These massive
stars near the end of their lives were rich in this short-lived element, meaning
nuclear reactions within the stars must be producing it. This evidence was used to bolster the then unproven
theory that stars are where
nucleosynthesis of the heavier elements occurs.
[20] More recently, such observations provided evidence that elements were being formed by
neutron capture in the
s-process.
Since its discovery, there have been many searches in terrestrial materials for natural sources. In 1962, technetium-99 was isolated and identified in
pitchblende from the
Belgian Congo in very small quantities (about 0.2 ng/kg);
there it originates as a
spontaneous fission product of
uranium-238. This discovery was made by B.T. Kenna and P.K. Kuroda.
[21] There is also evidence that the
Oklo natural nuclear fission reactor produced significant amounts of technetium-99, which has since decayed to ruthenium-99.
Occurrence and production
Natural production
Since technetium is unstable, only minute traces occur naturally in the
Earth's crust as a spontaneous
fission product of
uranium. In 1999 David Curtis (see above) estimated that a kilogram of uranium contains 1 nanogram (1×10
−9 g) of technetium.
[22] Extraterrestrial technetium was found in some
red giant stars (S-, M-, and N-types) that contain an absorption line in their spectrum indicating the presence of this element.
[23]
Byproduct production in fission wastes
In contrast with the rare natural occurrence, bulk quantities of technetium-99 are produced each year from
spent nuclear fuel rods, which contain various fission products. The fission of a gram of the rare isotope
uranium-235 in
nuclear reactors yields 27 mg of
99Tc, giving technetium a
fission yield of 6.1%.
[24] Other
fissionable isotopes also produce similar yields of technetium.
It is estimated that up to 1994, about 49,000 T
Bq (78
metric tons) of technetium was produced in nuclear reactors, which is by far the dominant source of terrestrial technetium.
[25] However, only a fraction of the production is used commercially.
As of 2005, technetium-99 is available to holders of an
ORNL permit for
US$83/g plus packing charges.
[26]
Since the yield of technetium-99 as a
product of the
nuclear fission of both
uranium-235 and
plutonium-239 is moderate, it is present in
radioactive waste of fission reactors and is produced when a
fission bomb is detonated. The amount of artificially produced technetium in the environment exceeds its natural occurrence to a large extent. This is due to release by atmospheric
nuclear testing along with the disposal and processing of high-level
radioactive waste. Due to its high fission yield and relatively high half-life, technetium-99 is one of the main components of nuclear waste. Its decay, measured in becquerels per amount of spent fuel, is dominant at about 10
4 to 10
6 years after the creation of the nuclear waste.
An estimated 160 T
Bq (about 250 kg) of technetium-99 was released into the environment up to 1994 by atmospheric nuclear tests.
The amount of technetium-99 from nuclear reactors released into the environment up to 1986 is estimated to be on the order of 1000 TBq (about 1600 kg), primarily by
nuclear fuel reprocessing; most of this was discharged into the sea. In recent years, reprocessing methods have improved to reduce emissions, but
as of 2005 the primary release of technetium-99 into the environment is by the
Sellafield plant, which released an estimated 550 TBq (about 900 kg) from 1995–1999 into the
Irish Sea. From 2000 onwards the amount has been limited by regulation to 90 TBq (about 140 kg) per year.
[27]
As a result of nuclear fuel reprocessing, technetium has been discharged into the sea in a number of locations, and some seafood contains tiny but measurable quantities. For example,
lobster from west
Cumbria contains small amounts of technetium.
[28] The
anaerobic,
spore-forming
bacteria in the ''Clostridium''
genus are able to reduce Tc(VII) to Tc(IV). ''Clostridia'' bacteria play a role in reducing iron,
manganese and
uranium, thereby affecting these elements' solubility in soil and sediments. Their ability to reduce technetium may determine a large part of Tc's mobility in industrial wastes and other subsurface environments.
[29]
The long half-life of technetium-99 and its ability to form an
anionic species makes it (along with
129I) a major concern when considering long-term disposal of high-level radioactive waste. In addition, many of the processes designed to remove fission products from medium-active process streams in reprocessing plants are designed to remove
cationic species like
caesium (''e.g.,''
137Cs) and
strontium (''e.g.,''
90Sr). Hence the pertechnetate is able to escape through these treatment processes. Current disposal options favor burial in geologically stable rock. The primary danger with such a course is that the waste is likely to come into contact with water, which could leach radioactive contamination into the environment. The anionic pertechnetate and
iodide are less able to absorb onto the surfaces of minerals so they are likely to be more mobile.
By comparison
plutonium,
uranium, and
caesium are much more able to bind to soil particles. For this reason, the environmental chemistry of technetium is an active area of research. An alternative disposal method,
transmutation, has been demonstrated at
CERN for technetium-99. This transmutation process is one in which the technetium (
99Tc as a
metal target) is bombarded with
neutrons to form the shortlived
100Tc (half life = 16 seconds) which decays by
beta decay to
ruthenium (
100Ru). One disadvantage of this process is the need for a very pure technetium target, while small traces of other fission products are likely to slightly increase the activity of the irradated target if small traces of the
minor actinides (such as
americium and
curium) are present in the target then they are likely to undergo fission to form
fission products. In this way, a small activity and amount of minor actinides leads to a very high level of radioactivity in the irradated target. The formation of
106Ru (half life 374 days) from the ''fresh fission'' is likely to increase the activity of the final ruthenium metal, which will then require a longer cooling time after irradiation before the
ruthenium can be used.
The actual production of technetium-99 from spent nuclear fuel is a long process. During fuel reprocessing, it appears in the waste liquid, which is highly radioactive. After sitting for several years, the radioactivity has fallen to a point where extraction of the long-lived isotopes, including technetium-99, becomes feasible. Several chemical extraction processes are used yielding technetium-99 metal of high purity.
Neutron activiation of molybdenum or other pure elements
The
meta stable (a state where the nucleus is in an excited state) isotope
99mTc is produced as a
fission product from the fission of
uranium or
plutonium in
nuclear reactors. Due to the fact that used fuel is allowed to stand for several years before reprocessing, all
99Mo and
99mTc will have decayed by the time that the fission products are separated from the
major actinides in conventional nuclear reprocessing. The PUREX
raffinate will contain a high concentration of technetium as TcO
4- but almost all of this will be
99Tc. The vast majority of the
99mTc used in medical work is formed from
99Mo which is formed by the
neutron activation of
98Mo.
99Mo has a half-life of 67 hours, so short-lived
99mTc (half-life: 6 hours), which results from its decay, is being constantly produced.
[30] The hospital then chemically extracts the technetium from the solution by using a
technetium-99m generator ("technetium cow," also occasionally called a molybdenum cow).
The normal technetium cow is an
alumina column which contains molybdenum-98; inasmuch as aluminium has a small neutron cross section, it is convenient for an alumina column bearing inactive
98Mo to be irradated with neutrons to make the radioactive Mo-99 column for the technetium cow.
[31] By working in this way, there is no need for the complex chemical steps which would be required to separate molybdenum from a fission product mixture. This alternative method requires that an enriched
uranium target be irradiated with
neutrons to form
99Mo as a
fission product, then separated.
[32]
Other technetium isotopes are not produced in significant quantities by fission; when needed, they are manufactured by neutron irradiation of parent isotopes (for example,
97Tc can be made by neutron irradiation of
96Ru).
Isotopes
Main articles: isotopes of technetium
Technetium is one of the two elements in the first 82 that have no stable
isotopes (in fact, it is the lowest-numbered element that is exclusively radioactive); the other such element is
promethium.
[33] The most stable
radioisotopes are
98Tc (
half-life of 4.2
Ma),
97Tc (half-life: 2.6 Ma) and
99Tc (half-life: 211.1
ka).
[34]
Twenty-two other radioisotopes have been characterized with
atomic masses ranging from 87.933
u (
88Tc) to 112.931 u (
113Tc). Most of these have half-lives that are less than an hour; the exceptions are
93Tc (half-life: 2.75 hours),
94Tc (half-life: 4.883 hours),
95Tc (half-life: 20 hours), and
96Tc (half-life: 4.28 days).
Technetium also has numerous
meta states.
97mTc is the most stable, with a half-life of 90.1 days (0.097 MeV). This is followed by
95mTc (half life: 61 days, 0.038 MeV), and
99mTc (half-life: 6.01 hours, 0.143 MeV).
99mTc only emits
gamma rays, subsequently decaying to
99Tc.
For isotopes lighter than the most stable isotope,
98Tc, the primary
decay mode is
electron capture, giving
molybdenum. For the heavier isotopes, the primary mode is
beta emission, giving
ruthenium, with the exception that
100Tc can decay both by beta emission and electron capture.
Technetium-99 is the most common and most readily available isotope, as it is a major product of the fission of uranium-235. One gram of
99Tc produces 6.2×10
8 disintegrations a second (that is, 0.62 G
Bq/g).
[36]
Stability of technetium isotopes
Technetium and
promethium are unusual light elements in that they have no stable isotopes. The reason for this is somewhat complicated.
Using the
liquid drop model for atomic nuclei, one can derive a semiempirical formula for the binding energy of a nucleus. This formula predicts a "valley of beta stability" along which
nuclides do not undergo beta decay. Nuclides that lie "up the walls" of the valley tend to decay by beta decay towards the center (by emitting an electron, emitting a
positron, or capturing an electron). For a fixed number of nucleons ''A'', the binding energies lie on one or more
parabolas, with the most stable nuclide at the bottom. One can have more than one parabola because isotopes with an even number of protons and an even number of neutrons are more stable than isotopes with an odd number of neutrons and an odd number of protons. A single beta decay then transforms one into the other. When there is only one parabola, there can be only one stable isotope lying on that parabola. When there are two parabolas, that is, when the number of nucleons is even, it can happen (rarely) that there is a stable nucleus with an odd number of neutrons and an odd number of protons (although this happens only in four instances). However, if this happens, there can be no stable isotope with an even number of neutrons and an even number of protons.
For technetium (''Z''=43), the valley of beta stability is centered at around 98 nucleons. However, for every number of nucleons from 95 to 102, there is already at least one stable nuclide of either molybdenum (''Z''=42) or ruthenium (''Z''=44). For the isotopes with odd numbers of nucleons, this immediately rules out a stable isotope of technetium, since there can be only one stable nuclide with a fixed odd number of nucleons. For the isotopes with an even number of nucleons, since technetium has an odd number of protons, any isotope must also have an odd number of neutrons. In such a case, the presence of a stable nuclide having the same number of nucleons and an even number of protons rules out the possibility of a stable nucleus.
[37]
References
Works cited
;'Prose'
★ ''The Encyclopedia of the Chemical Elements'', edited by Cifford A. Hampel, "Technetium" entry by S. J. Rimshaw (New York; Reinhold Book Corporation; 1968; pages 689–693) Library of Congress Catalog Card Number: 68–29938
★ ''Nature's Building Blocks: An A-Z Guide to the Elements'', by John Emsley (New York; Oxford University Press; 2001; pages 422–425) ISBN 0-19-850340-7
★ The radiochemical Manual, 2nd Ed, edited by B.J. Wilson, 1966.
★
Los Alamos National Laboratory – Technetium (viewed
1 December 2002 and
22 April 2005)
★ WebElements.com "Technetium"
Uses (viewed
1 December 2002 and
22 April 2005)
★ EnvironmentalChemistry.com
Nuclides / Isotopes (viewed
1 December 2002 and
22 April 2005. JavaScript required, browser-restricted access)
★
''Elentymolgy and Elements Multidict'' by Peter van der Krogt, "Technetium" (viewed
30 April 2005; Last updated
10 April 2005 )
★
''History of the Origin of the Chemical Elements and Their Discoverers'' by Norman E. Holden (viewed
30 April 2005; last updated
12 March 2004)
★ ''
Technetium as a Material for AC Superconductivity Applications'' by S. H. Autler, Proceedings of the 1968 Summer Study on Superconducting Devices and Accelerators
★ ''
Technetium heart scan'', Dr. Joseph F. Smith Medical library (viewed
23 April 2005)
★ ''
Gut transfer and doses from environmental technetium'', J D Harrison et al 2001 ''J. Radiol. Prot.'' 21 9–11, Invited Editorial
★ ''
Ida Tacke and the warfare behind the discovery of fission'', by Kevin A. Nies (viewed
23 April 2005)
★ ''
TECHNETIUM'' by John T. Armstrong (viewed
23 April 2005)
★ ''
Technetium-99 Behaviour in the Terrestrial Environment - Field Observations and Radiotracer Experiments'', Keiko Tagami, Journal of Nuclear and Radiochemical Sciences, Vol. 4, No.1, pp. A1-A8, 2003
★ ''
Type 2 superconductors'' (viewed
23 April 2005)
★ ''
The CRC Handbook of Chemistry and Physics'', 85th edition, 2004–2005, CRC Press
★ K. Yoshihara, "Technetium in the Environment" in "Topics in Current Chemistry: Technetium and Rhenium", vol. 176, K. Yoshihara and T. Omori (eds.), Springer-Verlag, Berlin Heidelberg, 1996.
★ Schwochau, Klaus, ''Technetium'', Wiley-VCH (2000), ISBN 3-527-29496-1
★ ''
RADIOCHEMISTRY and NUCLEAR CHEMISTRY'', Gregory Choppin, Jan-Olov Liljenzin, and Jan Rydberg, 3rd Edition, 2002,
the chapter on nuclear stability (pdf) (viewed 5 January 2007)
;'Table'
★
WebElements.com – Technetium, and
EnvironmentalChemistry.com – Technetium per the guidelines at
Wikipedia's WikiProject Elements (all viewed
1 December 2002)
★
Nudat 2 nuclide chart from the National Nuclear Data Center, Brookhaven National Laboratory
★ ''
Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides'', General Electric Company, 1989
Notes
1. ''LANL Periodic Table'', "Technetium" paragraph 3
2. ''The Encyclopedia of the Chemical Elements'', page 691, "Chemical Properties", paragraph 1
3. ''The Encyclopedia of the Chemical Elements'', page 692, "Analytical Methods of Determination", paragraph 1
4. The CRC Handbook, 85th edition, Line Spectra of the Elements
5. ''The Encyclopedia of the Chemical Elements'', page 691, paragraph 1
6. Schwochau, ''Technetium''
7. ''Technetium as a Material for AC Superconductivity Applications''
8. Reference for whole 99mTc medical use discussion except where specific cites are given: ''Nature's Building Blocks'', page 423, "Medical Element", paragraphs 2–4
9. ''The Encyclopedia of the Chemical Elements'', page 693, "Applications", paragraph 3 and ''Guide to the Elements'', page 123, paragraph 3
10. ''Nature's Building Blocks'', page 423, "Medical Element", paragraph 2
11. ''Technetium heart scan''
12. ''The Encyclopedia of the Chemical Elements'', page 693, "Applications", paragraph 3
13. ''History of the Origin of the Chemical Elements and Their Discoverers'', Individual Element Names and History, "Technetium"
14. Discovery of a new element 'nipponium': re-evaluation of pioneering works of Masataka Ogawa and his son Eijiro Ogawa, , H. K., YOSHIHARA, Atomic spectroscopy (Spectrochim. acta, Part B),
15. Armstrong, John T. "Technetium" ''Chemical & Engineering News'' (2003).
16. Nies, Kevin A. "Ida Tacke and the warfare behind the discovery of fission" (2001).
17. Using first-principles X-ray-emission spectral-generation algorithms developed at NIST, I simulated the X-ray spectra that would be expected for Van Assche's initial estimates of the Noddacks' residue compositions. The first results were surprisingly close to their published spectrum! Over the next couple of years, we refined our reconstruction of their analytical methods and performed more sophisticated simulations. The agreement between simulated and reported spectra improved further. Our calculation of the amount of element 43 required to produce their spectrum is very similar to the direct measurements of natural technetium abundance in uranium ore published in 1999 by Dave Curtis and colleagues at Los Alamos. We can find no other plausible explanation for the Noddacks' data than that they did indeed detect fission "masurium.#Armstrong, John T. "Technetium" ''Chemical & Engineering News'' (2003).
18. ''Nature's Building Blocks'', page 424, paragraph 2 and ''LANL Periodic Table'', "Technetium", paragraph 1
19. THE TRANSURANIUM PEOPLE The Inside Story, , , , University of California, Berkeley & Lawrence Berkeley National Laboratory, ,
20. ''Nature's Building Blocks'', page 422, "Cosmic Element", paragraph 1
21. ''LANL Periodic Table'', "Technetium"
22. ''Nature's Building Blocks'', page 423, "Element of History", paragraph 2
23. ''LANL Periodic Table'', "Technetium" paragraph 1
24. ''Encyclopedia of the Chemical Elements'', page 690, "Sources of Technetium", paragraph 1
25. Topics in current chemistry, vol 176, "Technetium in the environment"
26. The CRC Handbook of Chemistry and Physics, 85th edition, The Elements
27. Technetium-99 behaviour in the terrestrial environment
28. ''Gut transfer and doses from environmental technetium''
29. Arokiasamy J. Francis, Cleveland J. Dodge, G. E. Meinken. "Biotransformation of pertechnetate by ''Clostridia''" ''Radiochimica Acta'' '90' 09–11 (2002): 791.
30. ''Nature's Building Blocks'', page 423, paragraph 2
31. ''The radiochemical manual''
32. J. L. Snelgrove ''et al.,'' "Development and Processing of LEU Targets for Mo-99 Production" (1995).
33. ''LANL Periodic Table'', "Technetium" paragraph 2
34. EnvironmentalChemistry.com, "Technetium", Nuclides / Isotopes
35. CRC Handbook, 85th edition, table of the isotopes
36. ''The Encyclopedia of the Chemical Elements'', page 693, "Toxicology", paragraph 2
37. RADIOCHEMISTRY and NUCLEAR CHEMISTRY
External links
★
WebElements.com – Technetium
★
pubs.acs.org – ACS article on validity of Noddack and Tacke's discovery
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