Atomic bonds have been imaged for the first time before and after a chemical reaction. This feat has been described as "every chemist's dream" by the University of California Berkeley News Center.
The unexpected study began when Felix Fisher set out to transform long strings of carbon atoms into a 6-sided form called graphene. The reactions used could produce a number of different compounds, and his team wanted to be able to predict which molecules would form.
Fisher decided to make use of the atomic force microscope (AFM) operated by fellow UC Berkeley chemist Michael Crommie. These are the devices that image atoms indirectly by detecting the charge given off by their electron shells.
"A carbon monoxide molecule adsorbed onto the tip of the AFM 'needle' leaves a single oxygen atom as the probe. Moving this 'atomic finger' back and forth over the silver surface is like reading Braille, as if we were feeling the small atomic-scale bumps made by the atoms," Fischer said.
Fisher set the carbon molecules on a silver plate and applied heat, bringing the sample above 194 degrees Fahrenheit. The molecules transformed. When Fisher looked at the sample through the AFM, not only had he managed to take the world's first before-and-after shots of a molecular reaction on an atomic scale, but the technique used also showed the bonds between the atoms.
"This was what my teachers used to say that you would never be able to actually see, and now we have it here," Fischer said.
Although the molecular formations before and after the reaction each contained 26 carbon atoms and 14 of hydrogen, the configurations were radically different. Before heating, the molecules each contained three rings of carbon, and one of the products created had seven rings of five to six carbon atoms a piece.
Chemistry students are familiar with molecules and the bonds between them being pictured much like Tinker toys, called a stick-and-ball model. The new images show that reality looks a lot like this simple model.
The atomic bonds between carbon atoms are only around 0.000000008 inches long. Over half a million of them could fit across the width of a typical strand of hair.
The new images were reported by Fisher and other researchers in the May 30 issue of the journal Science.
