A paper has just been accepted (5 April 2010) for publication in Physical Review Letters.1

International team discovers element 117

A new chemical element has been added to the Periodic Table: A paper on the discovery of element 117 has been accepted for publication in Physical Review Letters.

Oak Ridge National Laboratory is part of a team that includes the Joint Institute of Nuclear Research (Dubna, Russia), the Research Institute for Advanced Reactors (Dimitrovgrad), Lawrence Livermore National Laboratory, Vanderbilt University and the University of Nevada Las Vegas. ORNL's role included production of the berkelium-249 isotope necessary for the target, which was subjected to an extended, months-long run at the heavy ion accelerator facility at Dubna, Russia.

"Without the berkelium target, there could have been no experiment," says ORNL Director of Strategic Capabilities Jim Roberto, who is a principal author on the PRL paper and who helped initiate the experiment. The berkelium was produced at the High Flux Isotope Reactor and processed at the adjoining Radiochemical Engineering & Development Laboratory as part of the most recent campaign to produce californium-252, a radioisotope widely used in industry and medicine.

"Russia had proposed this experiment in 2004, but since we had no californium production at the time, we couldn't supply the berkelium. With the initiation of californium production in 2008, we were able to implement a collaboration," Roberto says.
Professor Joe Hamilton of Vanderbilt University (who helped establish the Joint Institute for Heavy Ion Research at ORNL) introduced Roberto to Yuri Oganessian of Russia's JINR. Five months of the Dubna JINR U400 accelerator's calcium-48 beam - one of the world's most powerful - was dedicated to the project.

The massive effort identified a total of six atoms of element 117 and the critical reams of data that substantiate their existence.
The two-year experimental campaign began with a 250-day irradiation in HFIR, producing 22 milligrams of berkelium-249, which has a 320-day half-life. The irradiation was followed by 90 days of processing at REDC to separate and purify the berkelium. The Bk-249 target was prepared at Dimitrovgrad and then bombarded for 150 days at the Dubna facility. Lawrence Livermore, which now has been involved in the discovery of six elements with Dubna (113, 114, 115, 116, 117, and 118), contributed data analysis, and the entire team was involved in the assessment of the results.

This is the second element that ORNL has had a role in discovering, joining element 61, promethium, which was discovered at the Graphite Reactor during the Manhattan project and reported in 1946. ORNL, by way of its production of radioisotopes for research, has contributed to the discovery of a total of seven new elements.

Members of the ORNL team include the Physics Division's Krzysztof Rykaczewsi, Porter Bailey of the Nonreactor Nuclear Facilities Division, and Dennis Benker, Julie Ezold, Curtis Porter and Frank Riley of the Nuclear S&T Division. Roberto says the success of the element-117 campaign underscores the value of international collaborations in science.
"This use of ORNL isotopes and Russian accelerators is a tremendous example of the value of working together," he says. "The 117 experiment paired one of the world's leading research reactors--capable of producing the berkelium target material--with the exceptional heavy ion accelerator and detection capabilities at Dubna."

Islands of Stability

Roberto also says the experiment, in addition to discovering a new chemical element, has pushed the Periodic Table further into the neutron-rich regime for heaviest elements. "New isotopes observed in these experiments continue a trend toward higher lifetimes for increased neutron numbers, providing evidence for the proposed "island of stability" for super-heavy nuclei," he says. "Because the half-lives are getting longer, there is potential to study the chemistry of these nuclei," Roberto says. "These experiments and discoveries essentially open new frontiers of chemistry."

—Bill Cabage

The news about the claim was announced in a press release from the Oak Ridge National Laboratory.

• 1. Synthesis of a New Element with Atomic Number Z=117,
  Oganessian, Yu. Ts., Abdullin Sh. F., Bailey P. D., Benker D. E., Bennett M. E., Dmitriev S. N., Ezold J. G., Hamilton J. H., Henderson R. A., Itkis M. G., et al.
  , Phys. Rev. Lett., Apr/2010, Volume 104, Number 14, p.142502, (2010)
  

IUPAC has officially approved the name copernicium, with symbol Cn, for the element of atomic number 112. Priority for the discovery of this element was assigned, in accordance with the agreed criteria, to the Gesellschaft für Schwerionenforschung (GSI) (Center for Heavy Ion Research) in Darmstadt, Germany. The team at GSI proposed the name copernicium which has now been approved by IUPAC. Sigurd Hofmann , leader of the GSI team stated that the intent was to "salute an influential scientist who didn't receive any accolades in his own lifetime, and highlight the link between astronomy and the field of nuclear chemistry."

The name proposed by the Gesselschaft für Schwerionenforschung (GSI) lies within the long tradition of naming elements to honor famous scientists. Nicolaus Copernicus was born on 19 February 1473, in Torún, Poland and died on 24 May 1543, in Frombork/Frauenburg also in Poland. His work has been of exceptional influence on the philosophical and political thinking of mankind and on the rise of modern science based on experimental results. During his time as a canon of the Cathedral in Frauenburg, Copernicus spent many years developing a conclusive model for complex astronomical observations of the movements of the sun, moon, planets and stars. His work published as “De revolutionibus orbium coelestium, liber sixtus” in 1543 had very far reaching consequences. Indeed the Copernican model demanded major changes in the view of the world related to astronomy and physical forces and well as having theological and political consequences. The planetary system introduced by Copernicus has been applied to other analogous systems in which objects move under the influence of a force directed towards a common centre. Notably, on a microscopic scale this is the Bohr model of the atom with its nucleus and orbiting electrons.

The Recommendations will be published in the March issue of the IUPAC journal Pure and Applied Chemistry and is available online at Pure Appl. Chem., 2010, Vol. 82, No. 3, pp. pp 753-755 (doi: 10.1351/PAC-REC-09-08-20)

Attempts have been made at GSI to make element 120 (unbinilium). Several new elements have been made at GSI in the last few years. However after 120 days no decay chain of element 120 was found. With the total number of 2.6 × 10¹⁹ projectiles which impinged upon the target, it deduced that the stability in the region around Z=120, N=184 is not exceptionally high with respect to the neighbouring regions.

Currently it is not clear what proton number defines the location of the "island of stability". Various theoretical models suggest numbers of Z=114, 120 or 126. Workers at GSI investigated the element Z=120 (element 120, containing 120 protons within the nucleus). Three different projectile-target combinations all lead to the same compound nucleus ³⁰²120 or ³⁰²Ubn

• ⁶⁴Ni + ²³⁸U
• ⁵⁸Fe + ²⁴⁴Pu, and
• ⁵⁴Cr + ²⁴⁸Cm

The neutron number of the compound nucleus ³⁰²120 is N=182. This is only 2 neutrons below N=184 where the neutron shell closure is expected. Therefore, ³⁰²120 or ³⁰²Ubn is closer to the N=184 shell than any other so far produced compound nucleus with lower Z.

The largest production rate for Z=120 is predicted for the most mass asymmetric projectile/target combination ⁵⁴Cr + ²⁴⁸Cm. However, at SHIP this experiment was not possible so the reaction ⁶⁴Ni + ²³⁸U was studied. If the proton shell closure is at Z=120 then an enhanced production rate and half-live of the element 120 would be expected. Depending on the magnitude of the stabilization due to the closed shell, one could expect up to a few events per week for the isotopes ²⁹⁹120 and ²⁹⁸120 produced in ⁶⁴Ni + ²³⁸U reactions. The half-lives are expected to be of the order of some 10 μs, but in the end no luck, this time at least.

Single-bonded cubic form of nitrogenEveryone knows that elemental nitrogen exists in the atmosphere as dinitrogen, N₂. There is a triple bond between the two nitrogen atoms. This is true - but under certain conditions, a fascinating N-N single bonded phase has been characterized.1

In 1985 it was predicted that at high pressure, nitrogen would transform to a solid with a single-bonded crystalline structure called polymeric nitrogen. Later, it was proposed that it whould have a cubic gauche (cg-N) structure. Experimental evidence was scant however until 2004 when a team of scientists from Germany and Russia managed to make the compound directly from molecular nitrogen at temperatures above 2000 K and pressures above 110 GPa using a laser-heated diamond cell. The material was characterized by X-ray and Raman scattering methods we have identified this as the polymeric nitrogen (cg-N).

The phase is a stiff with a bulk modulus ≥300 GPa. This is characteristic of strong covalent solids. The polymeric nitrogen is metastable. The structure of N is polymeric with each nitrogen bound to three other nitrogen atoms. At a pressure of 115 GPa, each N-N bond length is 1.346 ± 0.004 Å. The N-N-N angles are all about 108.8°, very close to the ideal tetrahedral angle of just over 109°.

It did not prove possible to recover the polymeric nitrogen by releasing the pressure - in other words the polymer reverts to normal dinitrogen. The authors speculate that this form of nitrogen is a new class of single-bonded nitrogen materials that may have unique energy capacity properties (more than five times that of the most powerful energetic materials).

• 1. Single-bonded cubic form of nitrogen,
  Eremets, Mikhail I., Gavriliuk Alexander G., Trojan Ivan A., Dzivenko Dymitro A., and Boehler Reinhard
  , Nature Materials, 8/2004, Volume 3, Issue 8, p.558 - 563, (2004)
  

CoperniciumIn honour of scientist and astronomer Nicolaus Copernicus (1473-1543), the discovering team around Professor Sigurd Hofmann suggested the name copernicium with the element symbol Cp for the new element 112, discovered at the GSI Helmholtzzentrum für Schwerionenforschung (Center for Heavy Ion Research) in Darmstadt. It was Copernicus who discovered that the Earth orbits the Sun, thus paving the way for our modern view of the world. Thirteen years ago, element 112 was discovered by an international team of scientists at the GSI accelerator facility. A few weeks ago, the International Union of Pure and Applied Chemistry, IUPAC, officially confirmed their discovery. In around six months, IUPAC will officially endorse the new element's name. This period is set to allow the scientific community to discuss the suggested name copernicium before the IUPAC naming.

"After IUPAC officially recognized our discovery, we – that is all scientists involved in the discovery – agreed on proposing the name copernicium for the new element 112. We would like to honor an outstanding scientist, who changed our view of the world", says Sigurd Hofmann, head of the discovering team.

Copernicus was born 1473 in Torun; he died 1543 in Frombork, Poland. Working in the field of astronomy, he realized that the planets circle the Sun. His discovery refuted the then accepted belief that the Earth was the center of the universe. His finding was pivotal for the discovery of the gravitational force, which is responsible for the motion of the planets. It also led to the conclusion that the stars are incredibly far away and the universe inconceivably large, as the size and position of the stars does not change even though the Earth is moving. Furthermore, the new world view inspired by Copernicus had an impact on the human self-concept in theology and philosophy: humankind could no longer be seen as the center of the world.

With its planets revolving around the Sun on different orbits, the solar system is also a model for other physical systems. The structure of an atom is like a microcosm: its electrons orbit the atomic nucleus like the planets orbit the Sun. Exactly 112 electrons circle the atomic nucleus in an atom of the new element "copernicium".

Element 112 is the heaviest element in the periodic table, 277 times heavier than hydrogen. It is produced by a nuclear fusion, when bombarding zinc ions onto a lead target. As the element already decays after a split second, its existence can only be proved with the help of extremely fast and sensitive analysis methods. Twenty-one scientists from Germany, Finland, Russia and Slovakia have been involved in the experiments that led to the discovery of element 112.

Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. The discovering teams at GSI already named five of them: element 107 is called bohrium, element 108 hassium, element 109 meitnerium, element 110 darmstadtium, and element 111 is named roentgenium.

The discoverors at GSI
Darmstadt, June 10, 2009

The new element 112 discovered by GSI has been officially recognized and will be named by the Darmstadt group in due course. Their suggestion should be made public over this summer.

The element 112, discovered at the GSI Helmholtzzentrum für Schwerionenforschung (Centre for Heavy Ion Research) in Darmstadt, has been officially recognized as a new element by the International Union of Pure and Applied Chemistry (IUPAC). IUPAC confirmed the recognition of element 112 in an official letter to the head of the discovering team, Professor Sigurd Hofmann. The letter furthermore asks the discoverers to propose a name for the new element. Their suggestion will be submitted within the next weeks. In about 6 months, after the proposed name has been thoroughly assessed by IUPAC, the element will receive its official name. The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table.

“We are delighted that now the sixth element – and thus all of the elements discovered at GSI during the past 30 years – has been officially recognized. During the next few weeks, the scientists of the discovering team will deliberate on a name for the new element”, says Sigurd Hofmann. 21 scientists from Germany, Finland, Russia and Slovakia were involved in the experiments around the discovery of the new element 112.

Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. GSI has already named their officially recognized elements 107 to 111: element 107 is called Bohrium, element 108 Hassium, element 109 Meitnerium, element 110 Darmstadtium, and element 111 is named Roentgenium.

Modern surface chemistry – fuel cells, artificial fertilizers and clean exhaust

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2007 to Gerhard Ertl of the Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany "for his studies of chemical processes on solid surfaces".

The Nobel Prize in Chemistry for 2007 is awarded for groundbreaking studies in surface chemistry. This science is important for the chemical industry and can help us to understand such varied processes as why iron rusts, how fuel cells function and how the catalysts in our cars work. Chemical reactions on catalytic surfaces play a vital role in many industrial operations, such as the production of artificial fertilizers. Surface chemistry can even explain the destruction of the ozone layer, as vital steps in the reaction actually take place on the surfaces of small crystals of ice in the stratosphere. The semiconductor industry is yet another area that depends on knowledge of surface chemistry.

It was thanks to processes developed in the semiconductor industry that the modern science of surface chemistry began to emerge in the 1960s. Gerhard Ertl was one of the first to see the potential of these new techniques. Step by step he has created a methodology for surface chemistry by demonstrating how different experimental procedures can be used to provide a complete picture of a surface reaction. This science requires advanced high-vacuum experimental equipment as the aim is to observe how individual layers of atoms and molecules behave on the extremely pure surface of a metal, for instance. It must therefore be possible to determine exactly which element is admitted to the system. Contamination could jeopardize all the measurements. Acquiring a complete picture of the reaction requires great precision and a combination of many different experimental techniques.

Gerhard Ertl has founded an experimental school of thought by showing how reliable results can be attained in this difficult area of research. His insights have provided the scientific basis of modern surface chemistry: his method-ology is used in both academic research and the indust-rial development of chemical processes. The approach developed by Ertl is based not least on his studies of the Haber-Bosch process, in which nitrogen is extracted from the air for inclusion in artificial fertilizers. This reaction, which functions using an iron surface as its catalyst, has enormous economic significance because the availability of nitrogen for growing plants is often restricted. Ertl has also studied the oxidation of carbon monoxide on platinum, a reaction that takes place in the catalyst of cars to clean exhaust emissions.

A New Chemical Element in the Periodic Table
Source: http://www.gsi.de/portrait/Pressemeldungen/10062009_e.html

Provisional Recommendations
Inorganic Chemistry Division

Recommendation for the Naming of Element of Atomic Number 110

Prepared for publication by J. Corish and G. M. Rosenblatt

A joint IUPAC-IUPAP Working Party confirms the discovery of element number 110 and this by the collaboration of Hofmann et al. from the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany.

In accord with IUPAC procedures, the discoverers have proposed a name and symbol for the element. The Inorganic Chemistry Division Committee now recommends this proposal for acceptance. The proposed name is darmstadtium with symbol Ds. This proposal lies within the long established tradition of naming an element after the place of its discovery.

IUPAC have made a provisional recommendation about the name for element 111. To quote: "A joint IUPAC-IUPAP Working Party (JWP) has confirmed the discovery of element number 111 and this by the collaboration of Hofmann et al. from the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany. In accord with IUPAC procedures, the discoverers have proposed a name and symbol for the element. The Inorganic Chemistry Division Committee now recommends this proposal for acceptance. The proposed name is roentgenium with symbol Rg.

This proposal lies within the long established tradition of naming elements to honour famous scientists. Wilhelm Conrad Röntgen discovered X-rays in 1895."