Flerovium (114Fl) 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 289Fl in 1999 (or possibly 1998). Flerovium has six known isotopes, along with the unconfirmed 290Fl, and possibly two nuclear isomers. The longest-lived isotope is 289Fl with a half-life of 1.9 seconds, but 290Fl may have a longer half-life of 19 seconds.
List of isotopes
Isotopes and nuclear properties
Nucleosynthesis
Target-projectile combinations leading to Z=114 compound nuclei The below table contains various combinations of targets and projectiles which could be used to form compound nuclei with an atomic number of 114.
Cold fusion This section deals with the synthesis of nuclei of flerovium by so-called "cold" fusion reactions. These are processes which create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only.
208Pb(76Ge,xn)284−xFl The first attempt to synthesise flerovium in cold fusion reactions was performed at Grand accélérateur national d'ions lourds (GANIL), France in 2003. No atoms were detected, providing a yield limit of 1.2 pb. The team at RIKEN have indicated plans to study this reaction.
Hot fusion This section deals with the synthesis of nuclei of flerovium by so-called "hot" fusion reactions. These are processes which create compound nuclei at high excitation energy (~40–50 MeV, hence "hot"), leading to a reduced probability of survival from fission. The excited nucleus then decays to the ground state via the emission of 3–5 neutrons. Fusion reactions utilizing 48Ca nuclei usually produce compound nuclei with intermediate excitation energies (~30–35 MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relatively high yields from these reactions.
248Cm(40Ar,xn)288-xFl One of the first attempts at synthesis of superheavy elements was performed by Albert Ghiorso et al. and Stan Thompson et al. in 1968 at the Lawrence Berkeley National Laboratory using this reaction. No events attributable to superheavy nuclei were identified; this was expected as the compound nucleus 288Fl (with N = 174) falls ten neutrons short of the closed shell predicted at N = 184. This first unsuccessful synthesis attempt provided early indications of cross-section and half-life limits for superheavy nuclei producible in hot fusion reactions.
244Pu(48Ca,xn)292−xFl (x=2?,3,4,5) The first experiments on the synthesis of flerovium were performed by the team in Dubna in November 1998. They were able to detect a single, long decay chain, assigned to 289Fl. The reaction was repeated in 1999 and a further two atoms of flerovium were detected. The products were assigned to 288Fl. The team further studied the reaction in 2002. During the measurement of the 3n, 4n, and 5n neutron evaporation excitation functions they were able to detect three atoms of 289Fl, twelve atoms of the new isotope 288Fl, and one atom of the new isotope 287Fl. Based on these results, the first atom to be detected was tentatively reassigned to 290Fl or 289mFl, whilst the two subsequent atoms were reassigned to 289Fl and therefore belong to the unofficial discovery experiment. In an attempt to study the chemistry of copernicium as the isotope 285Cn, this reaction was repeated in April 2007. Surprisingly, a PSI-FLNR directly detected two atoms of 288Fl forming the basis for the first chemical studies of flerovium. In June 2008, the experiment was repeated in order to further assess the chemistry of the element using the 289Fl isotope. A single atom was detected seeming to confirm the noble-gas-like properties of the element. During May–July 2009, the team at GSI studied this reaction for the first time, as a first step towards the synthesis of tennessine. The team were able to confirm the synthesis and decay data for 288Fl and 289Fl, producing nine atoms of the former isotope and four atoms of the latter.
242Pu(48Ca,xn)290−xFl (x=2,3,4,5) The team at Dubna first studied this reaction in March–April 1999 and detected two atoms of flerovium, assigned to 287Fl. The reaction was repeated in September 2003 in order to attempt to confirm the decay data for 287Fl and 283Cn since conflicting data for 283Cn had been collected (see copernicium). The Russian scientists were able to measure decay data for 288Fl, 287Fl and the new isotope 286Fl from the measurement of the 2n, 3n, and 4n excitation functions. In April 2006, a PSI-FLNR collaboration used the reaction to determine the first chemical properties of copernicium by producing 283Cn as an overshoot product. In a confirmatory experiment in April 2007, the team were able to detect 287Fl directly and therefore measure some initial data on the atomic chemical properties of flerovium. The team at Berkeley, using the Berkeley gas-filled separator (BGS), continued their studies using newly acquired 242Pu targets by attempting the synthesis of flerovium in January 2009 using the above reaction. In September 2009, they reported that they had succeeded in detecting two atoms of flerovium, as 287Fl and 286Fl, confirming the decay properties reported at the FLNR, although the measured cross sections were slightly lower; however the statistics were of lower quality. In April 2009, the collaboration of Paul Scherrer Institute (PSI) and Flerov Laboratory of Nuclear Reactions (FLNR) of JINR carried out another study of the chemistry of flerovium using this reaction. A single atom of 283Cn was detected. In December 2010, the team at the LBNL announced the synthesis of a single atom of the new isotope 285Fl with the consequent observation of 5 new isotopes of daughter elements.
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