Oct 14, 2010 10:29 GMT  ·  By

A team of researchers that arguably had too much time on its hands announces that it managed to count the number of atoms in a kilogram of silicon. They did so by dividing the quantity into smaller volumes.

In science, this number is known as the Avogadro's constant, and it refers to the atoms that can be found in any kilogram of matter, regardless of the chemical.

Materials scientists have been trying to determine its value with great precision for a long time. Various estimates exist, but the new one is likely the most precise to date.

The group reveals that Avogadro's constant is 6.02214084(18) × 10^23, which means that this is how many atoms can be found in a mole of silicon, Technology Review reports.

Such an intensive investigation was only made possible by an international consortium of scientists, which worked closely together to defeat the resource-intensive challenge.

According to the team, work on this project began 6 years ago, when researchers at the Central Design Bureau of Machine Building in St. Petersburg created silicon fluoride that had a very specific isotopic content.

The sample was then converted into a polycrystal of silicon hydride, by a group based at the Russian Academy of Science's Institute of Chemistry of High-Purity Substances.

By 2007, scientists at the Leibniz-Institut fur Kristallzuchtung, in Berlin, Germany, had grown a 5-kilogram lump of pure silicon from the crystals.

Lumps from this sample were then sent to the Australian Center for Precision Optics, where they were converted in quasi-perfect sphere.

Using an x-ray interferometer, th researchers determined the the crystal structure of the left over silicon. The group then analyzed the surface of the crystals.

This allowed them to determine what kind of crud had built up on them. This was an important factor to be taken into account when final calculations were made.

Copper, nickel and silicon oxides were just some of the substances that had built up on the surface of the crystals.

The mass of the silicon spheres where then weighed by comparison to the platinum-iridium test kilograms at the PTB (Physikalisch-Technische Bundesanstalt) in Germany, the National Metrology Institute of Japan, and the Bureau International des Poids et Mesures, in France.

“Our result leads to more consistent numerical values for the fundamental physical constants,” the team says.

The paper detailing the work is called “An Accurate Determination Of The Avogadro Constant By Counting The Atoms In A Si-28 Crystal.” It appears in the online scientific journal arXiv.