Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Unravelling Relativistic Effects in the Heaviest Actinide Element


The first-time measurement of the first ionization potential of lawrencium (element 103)

An international collaboration led by the research group of superheavy elements at the Japan Atomic Energy Agency (JAEA), Tokai, Japan has achieved the ionization potential measurement of lawrencium (element 103) with a novel-type technique at the JAEA tandem accelerator.

The gray tantalum tube surrounded by two heating elements in the center of the picture is part of the recently developed surface ion source installed in the JAEA-ISOL system in the JAEA tandem accelerator.

photo: Tetsuya K. Sato, JAEA

Based on the empirically developed "actinide concept", and in agreement with theoretical calculations, in today’s Periodic Table the series of actinide elements terminates with element 103, lawrencium (Lr). Now researchers have measured the first ionization potential of Lr, which reflects the binding energy of the most weakly-bound valence electron in lawrencium’s atomic shell.

Effects of relativity strongly affect this energy, and the experimental result is in excellent agreement with a new theoretical calculation, which includes these effects. It was shown that removing the outermost electron requires least energy in Lr among all actinides, as was expected. This validates the position of Lr as the last actinide element and confirms the architecture of the Periodic Table.

Since the introduction of the "actinide concept" as the most dramatic modern revision of the Periodic Table of the Elements by Glenn T. Seaborg in the 1940s, the element with atomic number 103, lawrencium (Lr), played a crucial role as the last element in the actinide series.

This special position turned out to set this element into the focus of questions on the influence of relativistic effects and the determination of properties confirming its position as the last actinide element. Consequently, the quest for data on chemical and physical properties of Lr was driving experimental and theoretical studies.

Two aspects most frequently addressed concerned its ground state electronic configuration and the value of its first ionization potential. As the last element in the actinide series, and similar to lutetium (Lu) as the last element in the lanthanide series, it was expected that Lr has a very low first ionization potential that is strongly influenced by relativistic effects.

However, Lr is only accessible atom-at-a-time in syntheses at heavy-ion accelerators, and only short-lived isotopes are known. Therefore, experimental investigations on Lr are very rare and have so far been limited to a few studies of some basic chemical properties.

In their new work, for which the international research collaboration exploited a novel combination and advancement of methods and techniques, the researchers report on the first and accurate measurement of the first ionization potential of Lr. For the experiment, the Institute of Nuclear Chemistry at Johannes Gutenberg University Mainz purified and prepared the exotic target material californium (element 98). The material was converted into a target in Japan and then exposed to a beam of boron ions (element 5).

The experiment was supplemented by theoretical calculations undertaken by scientists at the Helmholtz Institute Mainz (HIM) and at Tel Aviv University of Israel using the most up-to-date quantum chemical methods to quantify the ionization energy. The very good agreement between calculated and experimental result validates the quantum chemical calculations. The experimental technique opens up new perspectives for similar studies of yet more exotic, superheavy elements.

The international team consists of research groups from JAEA, the Institute of Nuclear Chemistry at Johannes Gutenberg University Mainz (JGU), Germany, the Helmholtz Institute Mainz (HIM), Germany, the GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany, the European Organization for Nuclear Research (CERN), Geneva, Switzerland, Ibaraki University, Japan, Niigata University, Japan, Hiroshima University, Japan, Massey University, Auckland, New Zealand, and Tel Aviv University, Israel.

The new findings have been presented in the NATURE magazine.

Tetsuya K. Sato et al.
Measurement of the first ionization potential of lawrencium, element 103
NATURE 520, 209-211, 9. April 2015
DOI: 10.1038/nature14342

The periodic table of elements including in the colored block at the bottom the lanthanides (Ln) and actinides (An). The height of each column indicates the relative first ionization potential of the corresponding element. The result obtained for lawrencium (Lr) is shown by the red column. The binding energy of the least bound valence electron in lawrencium is thus weaker than that in all other actinides and all other lanthanides.
Ill.: Kazuaki Tsukada, JAEA
The ionization energy of heavy lanthanides (black) and actinides (red) with the current result for lawrencium (Lr). The filled circle symbols represent values recorded in experiments, the ring symbols are estimated values. The two values for lawrencium are in excellent agreement, emphasizing the close correspondence between the theoretical expectations and experimental findings.
Ill.: Tetsuya K. Sato, JAEA
The gray tantalum tube surrounded by two heating elements in the center of the picture is part of the recently developed surface ion source installed in the JAEA-ISOL system in the JAEA tandem accelerator.
photo: Tetsuya K. Sato, JAEA

Further information:
Professor Dr. Christoph Düllmann
Institute of Nuclear Chemistry
Johannes Gutenberg University Mainz (JGU)
55099 Mainz, GERMANY
phone +49 6131 39-25852
fax +49 6131 39-20811

Weitere Informationen: – NATURE article "Exotic atom struggles to find its place in the periodic table" on the original publication – NATURE News & Views article "Nuclear chemistry: Lawrencium bridges a knowledge gap" - Superheavy Elements Chemistry Group

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Don't Give the Slightest Chance to Toxic Elements in Medicinal Products
23.03.2018 | Physikalisch-Technische Bundesanstalt (PTB)

nachricht North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>