Rubidium is the chemical element with atomic number 37, symbol Rb. It is
an alkali metal, soft and silvery, whose melting temperature is only 39.3 ¡ã C.
It can be kept liquid at room temperature thanks to the phenomenon of
supercooling, such as cesium and gallium.
Its name comes from the Latin rubidus (dark red), due to the red color of the
spectral lines which enabled Robert Wilhelm Bunsen and Gustav Kirchhoff to
detect it in 1861 in lepidolite. He was isolated the following year by Bunsen.
Like other alkali metals, it ignites spontaneously on contact with air and
reacts violently with water.
In the form of Bose-Einstein condensate, it has the property of reducing the
speed of light passing through it to less than 60 km / h.
Rubidium has 32 known isotopes, with a mass number varying between 71 and 102,
and 12 nuclear isomers. Only two of these isotopes are found in nature, 85Rb
(72.2%), the only stable isotope of rubidium (making it a monoisotopic element)
and radioactive 87Rb (27.8%). Natural rubidium is thus radioactive enough to
impress a photographic film in thirty to sixty days6. Rubidium is assigned a
standard atomic mass of 85.4678 (3)
Photovoltaic cells: it is used in alloy with cesium.
Tempered safety glass: the addition of rubidium carbonate (Rb2CO3) or rubidium
oxide (Rb2O) allows safety glass to be obtained by tempering.
Medicine:
Review of myocardial perfusion in nuclear medicine: due to its similarity to
potassium, the radioactive positron emitter isotope, 82Rb, of short half-life
(75 seconds), is used as an indicator of PET ischemia and use as an 81 m krypton
generator in pulmonary scintigraphy (Rb81).
Manufacture of certain nooanaleptic drugs.
Atomic physics: The rubidium atom (both its isotopes 85 and 87) is very
frequently used for experiments in atomic physics. Indeed, certain transitions
of this atom correspond to conventional laser wavelengths (780 nm for the 5s-5p
transition in particular), which facilitates the experiments. Among others,
rubidium can be used for the construction of atomic clocks using the hyperfine
transition from 87Rb to 6.834 682 611 GHz 7.
The use of this transition makes it possible to obtain compact and low-cost
commercial clocks, with a relative frequency stability of 5 ¡Á 10−11 (ie a
possible error of 1 second over a little over 600 years 8). There are also
clocks called ¡°atomic fountains¡±, operating with laser-cooled and manipulated
87Rb, which reach much better relative frequency stabilities, between 10−13 and
10−14 9.
Gas sensor for cathode ray tube and electronic tube: it is used as a getter (gas
molecule sensor) to complete the vacuum.
It is sometimes used to get the purple color in fireworks
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rhenium germanium zirconium cadmium hafnium
barium lithium beryllium strontium calcium
Tantalum gadolinium samarium yttrium ytterbium
Lutetium praseodymium holmium erbium thulium dysprosium
terbium europium lanthanum cerium neodymium scandium
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