Physicists at the University of Greifswald have investigated the smallest lead particles and found surprising decay pathways. They report their results in a series of publications, most recently in the journal Physical Review Letters.
Physicists distinguish between the size ranges of individual atoms and bulk matter. Between these, there are also so-called clusters, particles that can be made up of just a few and up to around a thousand atoms. Due to their size they have properties that differ from individual atoms and the bulk matter.
The Figure on the left is a schematic depiction of the laser irradiation of lead particles stored in a so-called Penning ion trap.
Grafik: Stephan König
And what is more, adding or removing just a single atom can substantially change the properties of a cluster. The study of cluster properties is one of the main research areas of the atomic and molecular physics group at the University of Greifswald’s Institute of Physics.
For the investigations that have now been presented, a high-purity lead wire was irradiated with laser pulses. This resulted in a plasma made up of electrons and lead atoms, some of them ionized. The plasma underwent strong cooling which allowed the lead atoms to aggregate, i.e. to form clusters.
The negatively charged clusters were captured in ion traps, further prepared for the actual measurements, and finally the reaction products were analyzed using mass spectrometry.
It had previously been observed that electron and laser irradiation of small negatively charged lead clusters made up of about 20 to approximately 40 atoms decay differently from what was known about other metals: Whilst copper, silver and gold clusters emit either single neutral atoms or their surplus electron, the lead clusters decay into bigger fragments (S. König et al., J. Phys. Chem., 2017, M. Wolfram et al, J. Phys. B 2018, S. König et al., Int. J. Mass Spectrom. (2017)). This decay into bigger pieces only disappears when using larger lead clusters resulting in the known evaporation of single atoms, which is also predicted by modelling small metal balls.
Recently, the studies investigating cluster irradiation of lead clusters by electrons and laser beams have been combined. This resulted in the first observation of the fission of multiply charged negative metal clusters. Furthermore, the decay behavior that deviates from that of the noble metal clusters continues, just like the return to the expected behavior with larger clusters.
These results may also be an indication for deviating behavior in further cluster properties. One of the conjectures based on the present observations is a semiconductor-to-metal transition with increasing size of the lead clusters, whilst even the smallest noble-metal clusters show a metallic behavior.
These results from fundamental research are of interest, for example, to scientists performing research into material science, who are looking for materials with new properties. Nanoparticles are particularly promising. Ideally, their properties could be controlled by their cluster size – although there is still a long way to go before the results can be applied to everyday devices.
The results on fission of multiply charged negative lead clusters appeared in the journal Physical Review Letters 120, 163001 – Published 16 April 2018
Fission of polyanionic metal clusters, S. König, A. Jankowski, G. Marx, L. Schweikhard, M. Wolfram, Physical Review Letters 120, 163001 (2018)
The photos can be downloaded and used for free for editorial purposes in combination with this press release. You must name the respective author of the images. To the photos
Contact at the University of Greifswald
Dr. Stephan König and Prof. Dr. Lutz Schweikhard
Institute of Physics
Felix-Hausdorff-Straße 6, 17487 Greifswald
Tel.: +49 3834 420 4700
Jan Meßerschmidt | idw - Informationsdienst Wissenschaft
APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie
First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences