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For physicist Percy Zahl, optimizing and preparing a noncontact atomic force microscope (nc-AFM) to directly visualize the chemical structure of a single molecule is a bit like playing a virtual reality video game. The process requires navigating and manipulating the tip of the instrument over the world of atoms and molecules, eventually picking some up at the right location and in the right way. If these challenges are completed successfully, you advance to the highest level, obtaining images that precisely show where individual atoms are located and how they are chemically bonded to other atoms. But take one wrong move, and it is game over. Time to start again.
"The nc-AFM has a very sensitive single-molecule tip that scans over a carefully prepared clean single-crystal surface at a constant height and "feels" the forces between the tip molecule and single atoms and bonds of molecules placed on this clean surface," explained Zahl, who is part of the Interface Science and Catalysis Group at the Center for Functional Nanomaterials (CFN), a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory. "It can take an hour or days to get this sensor working properly. You can't simply press a button; fine tuning is required. But all of this effort is definitely worthwhile once you see the images appearing like molecules in a chemistry textbook."
Beginning - Field - Chemistry - Scientists - Composition
Since the beginning of the field of chemistry, scientists have been able to determine the elemental composition of molecules. What has been more difficult is to figure out their chemical structures, or the particular arrangement of atoms in space. Knowing the chemical structure is important because it impacts the molecule's reactivities and other properties.
For example, Michael Faraday isolated benzene in 1825 from an oil gas residue. It was soon determined that benzene is composed of...
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