A stable cluster of aluminum atoms, Al13, acts as a single entity in chemical reactions, demonstrating properties similar to those of a halogen, reports a research team led by A. Welford Castleman Jr., the Evan Pugh Professor of Chemistry and Physics and the Eberly Family Distinguished Chair in Science at Penn State, in a paper to be published in the 2 April 2004 issue of the journal Science. Experimental results and theoretical calculations indicate that the cluster chemically resembles a "superhalogen" atom, retaining its properties during the reaction and in reaction products. Other team members include Denis E. Bergeron of the Penn State departments of chemistry and physics and Shiv N. Khanna of the Virginia Commonwealth University department of Physics. One implication of the research is the possibility of using such clusters as building blocks in nanoscale fabrication.
Figure 1: Charge density map of the highest occupied molecular orbital for the Al13I- cluster. Note the preservation of Al13I- icosahedral geometry, and the localized charge density on the aluminum cluster moiety. Color code: blue=aluminum; red=iodine.
Figure 2: Top Image: Lowest energy structure for Al13I-. Color code: blue=aluminum; red=iodine
Bottom Image: Charge density map of the highest occupied molecular orbital for Al13I-. Color code: blue=aluminum; red=iodine
The project focused on experimental evidence of the existence of a very stable cluster anion, Al13I-, prepared by the gas-phase reaction of aluminum clusters with HI gas. Mass spectrometric analysis indicated that the reaction produced relatively few products, the most abundant corresponding to Al13I-. Energy calculations to determine the bonding mechanism between the aluminum cluster and the iodine atom indicate that the extra electron is localized on the Al13 cluster, meaning that the cluster maintains its integrity throughout the reaction. Because the cluster has a greater electron affinity in the compound, or attraction to the free electron, than does iodine, it can be considered a "superhalogen."
"One of the themes of our research is using the clusters as building blocks for new nanoscale materials," says Castleman. "In many cases, people have worked from the top down; that is, subdividing matter to get it smaller and smaller. Were trying to work with atoms and molecules and put them together--working our way from the bottom up. If we can retain the properties of aggregates, as we put them together, perhaps we will be able to construct new nanoscale materials." The key to using the aggregates as building blocks is that they retain their individual properties during the reaction and do not coalesce into a large aggregate.
Barbara K. Kennedy | Penn State
A new tool for discovering nanoporous materials
23.05.2017 | Ecole Polytechnique Fédérale de Lausanne
Did you know that packaging is becoming intelligent through flash systems?
23.05.2017 | Heraeus Noblelight GmbH
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering