Physicists at the University of Manchester in the UK have carried out a new and extremely interesting series of experiments to measure the fine-structure constant of quantum mechanics. This dimensionless number (meaning it has no unit), denoted by alpha, describes the intensity of the electromagnetic interaction between electrons and photons in quantum mechanics. Its exact value is close to 1/137.
So far the most accurate way of measuring alpha involved measuring the quantum Hall effect on electrons in a cyclotron-a very sophisticated technique. Now the researchers from the School of Physics and Astronomy at Manchester, led by Professor Andre Geim, have suggested using graphene, a chemical state of carbon recently discovered, to measure the strength of the electromagnetic interaction between electrons and photons in a very direct manner. Graphene is a new variety of nanomaterial in the same family as the fullerenes, which consists of single layers of carbon atoms arranged in a hexagonal mesh.
Professor Geim and his team, who first discovered graphene in 2004, have now come up with a method for easily obtaining large sheets of graphene. Furthermore, they have realized that these one-atom thick sheets are not clear; they absorb about 2.3% of the light that passes through them. Their models and calculations then show that this percentage divided by Pi gives exactly the fine-structure constant alpha.
This experiment is indeed truly exceptional for its simplicity: a digital camera suffices to measure the amount of light that passes through the graphene sheets and a pocket calculator can be used to derive the final value for alpha!
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